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[Code of Federal Regulations]
[Title 49, Volume 5]
[Revised as of October 1, 2005]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR393]

[Page 361-449]
 
                        TITLE 49--TRANSPORTATION
 
                      DEPARTMENT OF TRANSPORTATION
 
PART 393_PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION

                            Subpart A_General

Sec.
393.1 Scope of the rules of this part.
393.3 Additional equipment and accessories.
393.5 Definitions.
393.7 Matter incorporated by reference.

       Subpart B_Lamps, Reflective Devices, and Electrical Wiring

393.9 Lamps operable, prohibition of obstructions of lamps and 
          reflectors.
393.11 Lamps and reflective devices.
393.13 Retroreflective sheeting and reflex reflectors, requirements for 
          semitrailers and trailers manufactured before December 1, 
          1993.
393.17 Lamps and reflectors--combinations in driveaway-towaway 
          operation.
393.19 Hazard warning signals.
393.20 [Reserved]
393.22 Combination of lighting devices and reflectors.
393.23 Power supply for lamps.
393.24 Requirements for head lamps, auxiliary driving lamps and front 
          fog lamps.
393.25 Requirements for lamps other than head lamps.
393.26 Requirements for reflex reflectors.
393.27 [Reserved]
393.28 Wiring systems.
393.29 [Reserved]
393.30 Battery installation.
393.31--393.33 [Reserved]

                            Subpart C_Brakes

393.40 Required brake systems.
393.41 Parking brake system.
393.42 Brakes required on all wheels.
393.43 Breakaway and emergency braking.
393.44 Front brake lines, protection.
393.45 Brake tubing and hoses; hose assemblies and end fittings.
393.46 [Reserved]
393.47 Brake actuators, slack adjusters, linings/pads and drums/rotors.
393.48 Brakes to be operative.
393.49 Single valve to operate all brakes.
393.50 Reservoirs required.
393.51 Warning signals, air pressure and vacuum gauges.
393.52 Brake performance.
393.53 Automatic brake adjusters and brake adjustment indicators.
393.55 Antilock brake systems.

                Subpart D_Glazing and Window Construction

393.60 Glazing in specified openings.
393.61 Truck and truck tractor window construction.
393.62 Emergency exits for buses.
393.63 [Reserved]

                         Subpart E_Fuel Systems

393.65 All fuel systems.
393.67 Liquid fuel tanks.
393.68 Compressed natural gas fuel containers.
393.69 Liquefied petroleum gas systems.

              Subpart F_Coupling Devices and Towing Methods

393.70 Coupling devices and towing methods, except for driveaway-towaway 
          operations.
393.71 Coupling devices and towing methods, driveaway-towaway 
          operations.

              Subpart G_Miscellaneous Parts and Accessories

393.75 Tires.
393.76 Sleeper berths.
393.77 Heaters.
393.78 Windshield wiping and washing systems.
393.79 Windshield defrosting and defogging systems.
393.80 Rear-vision mirrors.
393.81 Horn.
393.82 Speedometer.
393.83 Exhaust systems.
393.84 Floors.
393.85 [Reserved]
393.86 Rear impact guards and rear end protection.
393.87 Warning flags on projecting loads.
393.88 Television receivers.
393.89 Buses, driveshaft protection.
393.90 Buses, standee line or bar.
393.91 Buses, aisle seats prohibited.
393.92 [Reserved]
393.93 Seats, seat belt assemblies, and seat belt assembly anchorages.
393.94 Interior noise levels in power units.

                      Subpart H_Emergency Equipment

393.95 Emergency equipment on all power units.

         Subpart I_Protection Against Shifting and Falling Cargo

393.100 Which types of commercial motor vehicles are subject to the 
          cargo securement standards of this subpart, and what general 
          requirements apply?
393.102 What are the minimum performance criteria for cargo securement 
          devices and systems?
393.104 What standards must cargo securement devices and systems meet in 
          order

[[Page 362]]

          to satisfy the requirements of this subpart?
393.106 What are the general requirements for securing articles of 
          cargo?
393.108 How is the working load limit of a tiedown determined?
393.110 What else do I have to do to determine the minimum number of 
          tiedowns?
393.112 Must a tiedown be adjustable?
393.114 What are the requirements for front end structures used as part 
          of a cargo securement system?

           Specific Securement Requirements by Commodity Type

393.116 What are the rules for securing logs?
393.118 What are the rules for securing dressed lumber or similar 
          building products?
393.120 What are the rules for securing metal coils?
393.122 What are the rules for securing paper rolls?
393.124 What are the rules for securing concrete pipe?
393.126 What are the rules for securing intermodal containers?
393.128 What are the rules for securing automobiles, light trucks and 
          vans?
393.130 What are the rules for securing heavy vehicles, equipment and 
          machinery?
393.132 What are the rules for securing flattened or crushed vehicles?
393.134 What are the rules for securing roll-on/roll-off and hook lift 
          containers?
393.136 What are the rules for securing large boulders?

    Subpart J_Frames, Cab and Body Components, Wheels, Steering, and 
                           Suspension Systems

393.201 Frames.
393.203 Cab and body components.
393.205 Wheels.
393.207 Suspension systems.
393.209 Steering wheel systems.

    Authority: 49 U.S.C. 322, 31136, and 31502; Section 1041(b) of Pub. 
L. 102-240, 105 Stat. 1914, 1993 (1991); and 49 CFR 1.73.

    Source: 33 FR 19735, Dec. 25, 1968, unless otherwise noted.

    Editorial Note: Nomenclature changes to part 393 appear at 66 FR 
49874, Oct. 1, 2001.

                            Subpart A_General

    Source: 53 FR 49384, Dec. 7, 1988, unless otherwise noted.

Sec. 393.1  Scope of the rules in this part.

    (a) The rules in this part establish minimum standards for 
commercial motor vehicles as defined in Sec. 390.5 of this title. Only 
motor vehicles (as defined in Sec. 390.5) and combinations of motor 
vehicles which meet the definition of a commercial motor vehicle are 
subject to the requirements of this part. All requirements that refer to 
motor vehicles with a GVWR below 4,536 kg (10,001 pounds) are applicable 
only when the motor vehicle or combination of motor vehicles meets the 
definition of a commercial motor vehicle.
    (b) Every employer and employee shall comply and be conversant with 
the requirements and specifications of this part. No employer shall 
operate a commercial motor vehicle, or cause or permit it to be 
operated, unless it is equipped in accordance with the requirements and 
specifications of this part.

[70 FR 48025, Aug. 15, 2005]

Sec. 393.3  Additional equipment and accessories.

    Nothing contained in this subchapter shall be construed to prohibit 
the use of additional equipment and accessories, not inconsistent with 
or prohibited by this subchapter, provided such equipment and 
accessories do not decrease the safety of operation of the motor 
vehicles on which they are used.

Sec. 393.5  Definitions.

    As used in this part, the following words and terms are construed to 
mean:
    Aggregate working load limit. The summation of the working load 
limits or restraining capacity of all devices used to secure an article 
of cargo on a vehicle.
    Agricultural commodity trailer. A trailer that is designed to 
transport bulk agricultural commodities in off-road harvesting sites and 
to a processing plant or storage location, as evidenced by skeletal 
construction that accommodates harvest containers, a maximum length of 
28 feet, and an arrangement of air control lines and reservoirs that 
minimizes damage in field operations.
    Air brake system. A system, including an air-over-hydraulic brake 
subsystem, that uses air as a medium for transmitting pressure or force 
from the driver

[[Page 363]]

control to the service brake, but does not include a system that uses 
compressed air or vacuum only to assist the driver in applying muscular 
force to hydraulic or mechanical components.
    Air-over-hydraulic brake subsystem. A subsystem of the air brake 
system that uses compressed air to transmit a force from the driver 
control to a hydraulic brake system to actuate the service brakes.
    Anchor point. Part of the structure, fitting or attachment on a 
vehicle or article of cargo to which a tiedown is attached.
    Antilock Brake System or ABS means a portion of a service brake 
system that automatically controls the degree of rotational wheel slip 
during braking by:
    (1) Sensing the rate of angular rotation of the wheels;
    (2) Transmitting signals regarding the rate of wheel angular 
rotation to one or more controlling devices which interpret those 
signals and generate responsive controlling output signals; and
    (3) Transmitting those controlling signals to one or more modulators 
which adjust brake actuating forces in response to those signals.
    Article of cargo. A unit of cargo, other than a liquid, gas, or 
aggregate that lacks physical structure (e.g., grain, gravel, etc.) 
including articles grouped together so that they can be handled as a 
single unit or unitized by wrapping, strapping, banding or edge 
protection device(s).
    Auxiliary driving lamp. A lighting device mounted to provide 
illumination forward of the vehicle which supplements the upper beam of 
a standard headlighting system. It is not intended for use alone or with 
the lower beam of a standard headlamp system.
    Bell pipe concrete. Pipe whose flanged end is of larger diameter 
than its barrel.
    Blocking. A structure, device or another substantial article placed 
against or around an article of cargo to prevent horizontal movement of 
the article of cargo.
    Boat trailer. A trailer designed with cradle-type mountings to 
transport a boat and configured to permit launching of the boat from the 
rear of the trailer.
    Bracing. A structure, device, or another substantial article placed 
against an article of cargo to prevent it from tipping, that may also 
prevent it from shifting.
    Brake. An energy conversion mechanism used to stop, or hold a 
vehicle stationary.
    Brake power assist unit. A device installed in a hydraulic brake 
system that reduces the operator effort required to actuate the system, 
but which if inoperative does not prevent the operator from braking the 
vehicle by a continued application of muscular force on the service 
brake control.
    Brake power unit. A device installed in a brake system that provides 
the energy required to actuate the brakes, either directly or indirectly 
through an auxiliary device, with the operator action consisting only of 
modulating the energy application level.
    Brake tubing/hose. Metallic brake tubing, nonmetallic brake tubing 
and brake hose are conduits or lines used in a brake system to transmit 
or contain the medium (fluid or vacuum) used to apply the motor 
vehicle's brakes.
    Chassis. The load-supporting frame of a commercial motor vehicle, 
exclusive of any appurtenances which might be added to accommodate 
cargo.
    Clearance Lamps. Lamps that provide light to the front or rear, 
mounted on the permanent structure of the vehicle, such that they 
indicate the overall width of the vehicle.
    Container chassis trailer. A semitrailer of skeleton construction 
limited to a bottom frame, one or more axles, specially built and fitted 
with locking devices for the transport of intermodal cargo containers, 
so that when the chassis and container are assembled, the units serve 
the same function as an over the road trailer.
    Converter dolly. A motor vehicle consisting of a chassis equipped 
with one or more axles, a fifth wheel and/or equivalent mechanism, and 
drawbar, the attachment of which converts a semitrailer to a full 
trailer.
    Curb weight. The weight of a motor vehicle with standard equipment, 
maximum capacity of fuel, oil, and coolant; and, if so equipped, air 
conditioning

[[Page 364]]

and additional weight of optional engine. Curb weight does not include 
the driver.
    Dunnage. All loose materials used to support and protect cargo.
    Dunnage bag. An inflatable bag intended to fill otherwise empty 
space between articles of cargo, or between articles of cargo and the 
wall of the vehicle.
    Edge protector. A device placed on the exposed edge of an article to 
distribute tiedown forces over a larger area of cargo than the tiedown 
itself, to protect the tie-down and/or cargo from damage, and to allow 
the tiedown to slide freely when being tensioned.
    Electric brake system. A system that uses electric current to 
actuate the service brake.
    Emergency brake. A mechanism designed to stop a motor vehicle after 
a failure of the service brake system.
    Emergency brake system. A mechanism designed to stop a vehicle after 
a single failure occurs in the service brake system of a part designed 
to contain compressed air or brake fluid or vacuum (except failure of a 
common valve, manifold brake fluid housing or brake chamber housing).
    Fifth wheel. A device mounted on a truck tractor or similar towing 
vehicle (e.g., converter dolly) which interfaces with and couples to the 
upper coupler assembly of a semitrailer.
    Frame vehicle. A vehicle with skeletal structure fitted with one or 
more bunk units for transporting logs. A bunk unit consists of U-shaped 
front and rear bunks that together cradle logs. The bunks are welded, 
gusseted or otherwise firmly fastened to the vehicle's main beams, and 
are an integral part of the vehicle.
    Friction mat. A device placed between the deck of a vehicle and 
article of cargo, or between articles of cargo, intended to provide 
greater friction than exists naturally between these surfaces.
    Front fog lamp. A lighting device whose beam provides downward 
illumination forward of the vehicle and close to the ground, and is to 
be used only under conditions of rain, snow, dust, smoke or fog. A pair 
of fog lamps may be used alone, with parking, tail, side, marker, 
clearance and identification lamps, or with a lower beam headlamp at the 
driver's discretion in accordance with state and local use law.
    Fuel tank fitting. Any removable device affixed to an opening in the 
fuel tank with the exception of the filler cap.
    g. The acceleration due to gravity, 32.2 ft/sec\2\ (9.81 m/sec\2\).
    Grommet. A device that serves as a support and protection to that 
which passes through it.
    Hazard warning signal. Lamps that flash simultaneously to the front 
and rear, on both the right and left sides of a commercial motor 
vehicle, to indicate to an approaching driver the presence of a 
vehicular hazard.
    Head lamps. Lamps used to provide general illumination ahead of a 
motor vehicle.
    Heater. Any device or assembly of devices or appliances used to heat 
the interior of any motor vehicle. This includes a catalytic heater 
which must meet the requirements of Sec. 177.834(l)(2) of this title 
when Class 3 (flammable liquid) or Division 2.1 (flammable gas) is 
transported.
    Heavy hauler trailer. A trailer which has one or more of the 
following characteristics, but which is not a container chassis trailer:
    (1) Its brake lines are designed to adapt to separation or extension 
of the vehicle frame; or
    (2) Its body consists only of a platform whose primary cargo-
carrying surface is not more than 1,016 mm (40 inches) above the ground 
in an unloaded condition, except that it may include sides that are 
designed to be easily removable and a permanent ``front-end structure'' 
as that term is used in Sec. 393.106 of this title.
    Hook-lift container. A specialized container, primarily used to 
contain and transport materials in the waste, recycling, construction/
demolition and scrap industries, which is used in conjunction with 
specialized vehicles, in which the container is loaded and unloaded onto 
a tilt frame body by an articulating hook-arm.
    Hydraulic brake system. A system that uses hydraulic fluid as a 
medium for transmitting force from a service brake control to the 
service brake, and

[[Page 365]]

that may incorporate a brake power assist unit, or a brake power unit.
    Identification lamps. Lamps used to identify certain types of 
commercial motor vehicles.
    Integral securement system. A system on certain roll-on/roll-off 
containers and hook-lift containers and their related transport vehicles 
in which compatible front and rear hold down devices are mated to 
provide securement of the complete vehicle and its articles of cargo.
    Lamp. A device used to produce artificial light.
    Length of a manufactured home. The largest exterior length in the 
traveling mode, including any projections which contain interior space. 
Length does not include bay windows, roof projections, overhangs, or 
eaves under which there is no interior space, nor does it include 
drawbars, couplings or hitches.
    License plate lamp. A lamp used to illuminate the license plate on 
the rear of a motor vehicle.
    Longwood. All logs that are not shortwood, i.e., are over 4.9 m (16 
feet) long. Such logs are usually described as long logs or treelength.
    Low chassis vehicle. (1) A trailer or semitrailer manufactured on or 
after January 26, 1998, having a chassis which extends behind the 
rearmost point of the rearmost tires and which has a lower rear surface 
that meets the guard width, height, and rear surface requirements of 
Sec. 571.224 in effect on the date of manufacture, or a subsequent 
edition.
    (2) A motor vehicle, not described by paragraph (1) of this 
definition, having a chassis which extends behind the rearmost point of 
the rearmost tires and which has a lower rear surface that meets the 
guard configuration requirements of Sec. 393.86(b)(1).
    Manufactured home means a structure, transportable in one or more 
sections, which in the traveling mode, is eight body feet or more in 
width or forty body feet or more in length, or, when erected on site, is 
three hundred twenty or more square feet, and which is built on a 
permanent chassis and designed to be used as a dwelling with or without 
a permanent foundation when connected to the required utilities, and 
includes the plumbing, heating, air-conditioning, and electrical systems 
contained therein. Calculations used to determine the number of square 
feet in a structure will be based on the structure's exterior dimensions 
measured at the largest horizontal projections when erected on site. 
These dimensions will include all expandable rooms, cabinets, and other 
projections containing interior space, but do not include bay windows. 
This term includes all structures which meet the above requirements 
except the size requirements and with respect to which the manufacturer 
voluntarily files a certification pursuant to 24 CFR 3282.13 and 
complies with the standards set forth in 24 CFR part 3280.
    Multi-piece windshield. A windshield consisting of two or more 
windshield glazing surface areas.
    Parking brake system. A mechanism designed to prevent the movement 
of a stationary motor vehicle.
    Play. Any free movement of components.
    Pulpwood trailer. A trailer or semitrailer that is designed 
exclusively for harvesting logs or pulpwood and constructed with a 
skeletal frame with no means for attachment of a solid bed, body, or 
container.
    Rail vehicle. A vehicle whose skeletal structure is fitted with 
stakes at the front and rear to contain logs loaded crosswise.
    Rear extremity. The rearmost point on a motor vehicle that falls 
above a horizontal plane located 560 mm (22 inches) above the ground and 
below a horizontal plane located 1,900 mm (75 inches) above the ground 
when the motor vehicle is stopped on level ground; unloaded; its fuel 
tanks are full; the tires (and air suspension, if so equipped) are 
inflated in accordance with the manufacturer's recommendations; and the 
motor vehicle's cargo doors, tailgate, or other permanent structures are 
positioned as they normally are when the vehicle is in motion. 
Nonstructural protrusions such as taillamps, rubber bumpers, hinges and 
latches are excluded from the determination of the rearmost point.
    Reflective material. A material conforming to Federal Specification 
L-S-300, ``Sheeting and Tape, Reflective; Non-exposed Lens, Adhesive 
Backing,''

[[Page 366]]

(September 7, 1965) meeting the performance standard in either Table 1 
or Table 1A of SAE Standard J594f, ``Reflex Reflectors'' (January, 
1977).
    Reflex reflector. A device which is used on a vehicle to give an 
indication to an approaching driver by reflected lighted from the lamps 
on the approaching vehicle.
    Saddle-mount. A device, designed and constructed as to be readily 
demountable, used in driveaway-towaway operations to perform the 
functions of a conventional fifth wheel:
    (1) Upper-half. Upper-half of a ``saddle-mount'' means that part of 
the device which is securely attached to the towed vehicle and maintains 
a fixed position relative thereto, but does not include the ``king-
pin;''
    (2) Lower-half. Lower-half of a ``saddle-mount'' means that part of 
the device which is securely attached to the towing vehicle and 
maintains a fixed position relative thereto but does not include the 
``king-pin;'' and
    (3) King-pin. King-pin means that device which is used to connect 
the ``upper-half'' to the ``lower-half'' in such manner as to permit 
relative movement in a horizontal plane between the towed and towing 
vehicles.
    Service brake system. A primary brake system used for slowing and 
stopping a vehicle.
    Shoring bar. A device placed transversely between the walls of a 
vehicle and cargo to prevent cargo from tipping or shifting.
    Shortwood. All logs typically up to 4.9 m (16 feet) long. Such logs 
are often described as cut-up logs, cut-to-length logs, bolts or 
pulpwood. Shortwood may be loaded lengthwise or crosswise, though that 
loaded crosswise is usually no more than 2.6 m (102 inches) long.
    Sided vehicle. A vehicle whose cargo compartment is enclosed on all 
four sides by walls of sufficient strength to contain articles of cargo, 
where the walls may include latched openings for loading and unloading, 
and includes vans, dump bodies, and a sided intermodal container carried 
by a vehicle.
    Side extremity. The outermost point on a side of the motor vehicle 
that is above a horizontal plane located 560 mm (22 inches) above the 
ground, below a horizontal plane located 1,900 mm (75 inches) above the 
ground, and between a transverse vertical plane tangent to the rear 
extremity of the vehicle and a transverse vertical plane located 305 mm 
(12 inches) forward of that plane when the vehicle is unloaded; its fuel 
tanks are full; and the tires (and air suspension, if so equipped) are 
inflated in accordance with the manufacturer's recommendations. Non-
structural protrusions such as taillights, hinges and latches are 
excluded from the determination of the outermost point.
    Side marker lamp (Intermediate). A lamp mounted on the side, on the 
permanent structure of the motor vehicle that provides light to the side 
to indicate the approximate middle of the vehicle, when the motor 
vehicle is 9.14 meters (30 feet) or more in length.
    Side Marker Lamps. Lamps mounted on the side, on the permanent 
structure of the motor vehicle as near as practicable to the front and 
rear of the vehicle, that provide light to the side to indicate the 
overall length of the motor vehicle.
    Special purpose vehicle. (1) A trailer or semitrailer manufactured 
on or after January 26, 1998, having work-performing equipment that, 
while the motor vehicle is in transit, resides in or moves through the 
area that could be occupied by the horizontal member of the rear impact 
guard, as defined by the guard width, height and rear surface 
requirements of Sec. 571.224 (paragraphs S5.1.1 through S5.1.3), in 
effect on the date of manufacture, or a subsequent edition.
    (2) A motor vehicle, not described by paragraph (1) of this 
definition, having work-performing equipment that, while the motor 
vehicle is in transit, resides in or moves through the area that could 
be occupied by the horizontal member of the rear impact guard, as 
defined by the guard width, height and rear surface requirements of 
Sec. 393.86(b)(1).
    Split service brake system. A brake system consisting of two or more 
subsystems actuated by a single control designed so that a leakage-type 
failure of a pressure component in a single subsystem (except structural 
failure of a housing that is common to two or more subsystems) shall not 
impair the operation of any other subsystem.

[[Page 367]]

    Steering wheel lash. The condition in which the steering wheel may 
be turned through some part of a revolution without associated movement 
of the front wheels.
    Stop lamps. Lamps shown to the rear of a motor vehicle to indicate 
that the service brake system is engaged.
    Tail lamps. Lamps used to designate the rear of a motor vehicle.
    Tiedown. A combination of securing devices which forms an assembly 
that attaches articles of cargo to, or restrains articles of cargo on, a 
vehicle or trailer, and is attached to anchor point(s).
    Tow bar. A strut or column-like device temporarily attached between 
the rear of a towing vehicle and the front of the vehicle being towed.
    Tractor-pole trailer. A combination vehicle that carries logs 
lengthwise so that they form the body of the vehicle. The logs are 
supported by a bunk located on the rear of the tractor, and another bunk 
on the skeletal trailer. The tractor bunk may rotate about a vertical 
axis, and the trailer may have a fixed, scoping, or cabled reach, or 
other mechanical freedom, to allow it to turn.
    Trailer kingpin. A pin (with a flange on its lower end) which 
extends vertically from the front of the underside of a semitrailer and 
which locks into a fifth wheel.
    Turn signals. Lamps used to indicate a change in direction by 
emitting a flashing light on the side of a motor vehicle towards which a 
turn will be made.
    Upper coupler assembly. A structure consisting of an upper coupler 
plate, king-pin and supporting framework which interfaces with and 
couples to a fifth wheel.
    Upper coupler plate. A plate structure through which the king-pin 
neck and collar extend. The bottom surface of the plate contacts the 
fifth wheel when coupled.
    Vacuum brake system. A system that uses a vacuum and atmospheric 
pressure for transmitting a force from the driver control to the service 
brake, not including a system that uses vacuum only to assist the driver 
in applying muscular force to hydraulic or mechanical components.
    Void filler. Material used to fill a space between articles of cargo 
and the structure of the vehicle that has sufficient strength to prevent 
movement of the articles of cargo.
    Well. The depression formed between two cylindrical articles of 
cargo when they are laid with their eyes horizontal and parallel against 
each other.
    Wheels back vehicle. (1) A trailer or semitrailer manufactured on or 
after January 26, 1998, whose rearmost axle is permanently fixed and is 
located such that the rearmost surface of the tires (of the size 
recommended by the vehicle manufacturer for the rear axle) is not more 
than 305 mm (12 inches) forward of the transverse vertical plane tangent 
to the rear extremity of the vehicle.
    (2) A motor vehicle, not described by paragraph (1) of this 
definition, whose rearmost axle is permanently fixed and is located such 
that the rearmost surface of the tires (of the size recommended by the 
vehicle manufacturer for the rear axle) is not more than 610 mm (24 
inches) forward of the transverse vertical plane tangent to the rear 
extremity of the vehicle.
    Width of a manufactured home. The largest exterior width in the 
traveling mode, including any projections which contain interior space. 
Width does not include bay windows, roof projections, overhangs, or 
eaves under which there is no interior space.
    Windshield. The principal forward facing glazed surface provided for 
forward vision in operating a motor vehicle.
    Working load limit (WLL). The maximum load that may be applied to a 
component of a cargo securement system during normal service, usually 
assigned by the manufacturer of the component.

[53 FR 49384, Dec. 7, 1988, as amended at 63 FR 8339, Feb. 18, 1998; 63 
FR 24465, May 4, 1998; 64 FR 47707, Sept. 1, 1999; 67 FR 61224, Sept. 
27, 2002; 68 FR 56208, Sept. 30, 2003; 70 FR 48026, Aug. 15, 2005]

Sec. 393.7  Matter incorporated by reference.

    (a) Incorporation by reference. Part 393 includes references to 
certain matter or materials, as listed in paragraph (b) of this section. 
The text of the materials is not included in the regulations

[[Page 368]]

contained in part 393. The materials are hereby made a part of the 
regulations in part 393. The Director of the Federal Register has 
approved the materials incorporated by reference in accordance with 5 
U.S.C. 552(a) and 1 CFR part 51. For materials subject to change, only 
the specific version approved by the Director of the Federal Register 
and specified in the regulation are incorporated. Material is 
incorporated as it exists on the date of the approval and a notice of 
any change in these materials will be published in the Federal Register.
    (b) Matter or materials referenced in part 393. The matter or 
materials listed in this paragraph are incorporated by reference in the 
corresponding sections noted.
    (1) Auxiliary Upper Beam Lamps, Society of Automotive Engineers 
(SAE) J581, July 2004, incorporation by reference approved for Sec. 
393.24(b).
    (2) Front Fog Lamp, SAE J583, August 2004, incorporation by 
reference approved for Sec. 393.24(b).
    (3) Stop Lamps for Use on Motor Vehicles Less Than 2032 mm in 
Overall Width, SAE J586, March 2000, incorporation by reference approved 
for Sec. 393.25(c).
    (4) Stop Lamps and Front- and Rear-Turn Signal Lamps for Use on 
Motor Vehicles 2032 mm or more in Overall Width, SAE J2261, January 
2002, incorporated by reference approved for Sec. 393.25 (c).
    (5) Tail Lamps (Rear Position Lamps) for Use on Motor Vehicles Less 
Than 2032 mm in Overall Width, SAE J585, March 2000, incorporation by 
reference approved for Sec. 393.25(c).
    (6) Tail Lamps (Rear Position Lamps) for Use on Vehicles 2032 mm or 
More in Overall Width, SAE J2040, March 2002, incorporation by reference 
approved for Sec. 393.25(c).
    (7) Turn Signal Lamps for Use on Motor Vehicles Less Than 2032 mm in 
Overall Width, SAE J588, March 2000, incorporation by reference approved 
for Sec. 393.25(c).
    (8) Sidemarker Lamps for Use on Road Vehicles Less Than 2032 mm in 
Overall Width, SAE J592, August 2000, incorporation by reference 
approved for Sec. 393.25(c).
    (9) Directional Flashing Optical Warning Devices for Authorized 
Emergency, Maintenance, and Service Vehicles, SAE J595, January 2005, 
incorporation by reference approved for Sec. 393.25(e).
    (10) Optical Warning Devices for Authorized Emergency, Maintenance, 
and Service Vehicles, SAE J845, May 1997, incorporation by reference 
approved for Sec. 393.25(e).
    (11) Gaseous Discharge Warning Lamp for Authorized Emergency, 
Maintenance, and Service Vehicles, SAE J1318, May 1998, incorporation by 
reference approved for Sec. 393.25(e).
    (12) Reflex Reflectors, SAE J594, December 2003, incorporation by 
reference approved for Sec. 393.26(c).
    (13) Standard Specification for Retroreflective Sheeting for Traffic 
Control, American Society of Testing and Materials, ASTM D 4956-04, 
2004, incorporation by reference approved for Sec. 393.26(c).
    (14) Automobile, Truck, Truck-Tractor, Trailer, and Motor Coach 
Wiring, SAE J1292, October 1981, incorporated by reference approved for 
Sec. 393.28.
    (15) Long Stroke Air Brake Actuator Marking, SAE J1817, July 2001, 
incorporation by reference approved for Sec. 393.47(e).
    (16) American National Standard for Safety Glazing Materials for 
Glazing Motor Vehicles and Motor Vehicle Equipment Operating on Land 
Highways-Safety Standard, SAE Z26.1-1996, August 1997, incorporation by 
reference approved for Sec. 393.62(d).
    (17) Specification for Sound Level Meters, American National 
Standards Institute, S1.4-1983, incorporation by reference approved for 
Sec. 393.94(c).
    (18) Standard Specification for Strapping, Flat Steel and Seals, 
American Society for Testing and Materials (ASTM), D3953-97, February 
1998, incorporation by reference approved for Sec. 393.104(e).
    (19) Welded Steel Chain Specifications, National Association of 
Chain Manufacturers, November 15, 1999, incorporation by reference 
approved for Sec. 393.104(e).
    (20) Recommended Standard Specification for Synthetic Web Tiedowns, 
Web Sling and Tiedown Association,

[[Page 369]]

WSTDA-T1, 1998, incorporation by reference approved for Sec. 
393.104(e).
    (21) Wire Rope Users Manual, 2nd Edition, Wire Rope Technical Board 
November 1985, incorporation by reference approved for Sec. 393.104(e).
    (22) Cordage Institute rope standards approved for incorporation 
into Sec. 393.104(e):
    (i) PETRS-2, Polyester Fiber Rope, 3-Strand and 8-Strand 
Constructions, January 1993;
    (ii) PPRS-2, Polypropylene Fiber Rope, 3-Strand and 8-Strand 
Constructions, August 1992;
    (iii) CRS-1, Polyester/Polypropylene Composite Rope Specifications, 
Three-Strand and Eight-Strand Standard Construction, May 1979;
    (iv) NRS-1, Nylon Rope Specifications, Three-Strand and Eight-Strand 
Standard Construction, May 1979; and
    (v) C-1, Double Braided Nylon Rope Specifications DBN, January 1984.
    (c) Availability. The materials incorporated by reference are 
available as follows:
    (1) Standards of the Underwriters Laboratories, Inc. Information and 
copies may be obtained by writing to: Underwriters Laboratories, Inc., 
333 Pfingsten Road, Northbrook, Illinois 60062.
    (2) Specifications of the American Society for Testing and 
Materials. Information and copies may be obtained by writing to: 
American Society for Testing and Materials, 100 Barr Harbor Drive, West 
Conshohocken, Pennsylvania 19428-2959.
    (3) Specifications of the National Association of Chain 
Manufacturers. Information and copies may be obtained by writing to: 
National Association of Chain Manufacturers, P.O. Box 22681, Lehigh 
Valley, Pennsylvania 18002-2681.
    (4) Specifications of the Web Sling and Tiedown Association. 
Information and copies may be obtained by writing to: Web Sling and 
Tiedown Association, Inc., 5024-R Campbell Boulevard, Baltimore, 
Maryland 21236-5974.
    (5) Manuals of the Wire Rope Technical Board. Information and copies 
may be obtained by writing to: Wire Rope Technical Committee, P.O. Box 
849, Stevensville, Maryland 21666.
    (6) Standards of the Cordage Institute. Information and copies may 
be obtained by writing to: Cordage Institute, 350 Lincoln Street, 
<greek-i> 115, Hingham, Massachusetts 02043.
    (7) Standards of the Society of Automotive Engineers (SAE). 
Information and copies may be obtained by writing to: Society of 
Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, 
Pennsylvania 15096.
    (8) Standards of the American National Standards Institute (ANSI). 
Information and copies may be obtained by writing to: American National 
Standards Institute, 25 West 43rd Street, New York, New York 10036.
    (9) [Reserved].
    (10) All of the materials incorporated by reference are available 
for inspection at:
    (i) The Federal Motor Carrier Safety Administration, Office of Bus 
and Truck Standards and Operations, 400 Seventh Street, SW., Washington, 
DC 20590; and
    (ii) The National Archives and Records Administration (NARA). For 
information on the availability of this material at NARA, call 202-741-
6030, or go to: http://www.archives.gov/federal--register/code--of--
federal--regulations/ibr--locations.html.

[67 FR 61225, Sept. 27, 2002, as amended at 70 FR 48027, Aug. 15, 2005]

       Subpart B_Lamps, Reflective Devices, and Electrical Wiring

Sec. 393.9  Lamps operable, prohibition of obstructions of lamps and 
          reflectors.

    (a) All lamps required by this subpart shall be capable of being 
operated at all times. This paragraph shall not be construed to require 
that any auxiliary or additional lamp be capable of operating at all 
times.
    (b) Lamps and reflective devices/material required by this subpart 
must not be obscured by the tailboard, or by any part of the load, or 
its covering by dirt, or other added vehicle or work equipment, or 
otherwise. Exception: The conspicuity treatments on the front end 
protection devices may be obscured by part of the load being 
transported.

[70 FR 48027, Aug. 15, 2005]

[[Page 370]]

Sec. 393.11  Lamps and reflective devices.

    (a)(1) Lamps and reflex reflectors. Table 1 specifies the 
requirements for lamps, reflective devices and associated equipment by 
the type of commercial motor vehicle. The diagrams in this section 
illustrate the position of the lamps, reflective devices and associated 
equipment specified in Table 1. All commercial motor vehicles 
manufactured on or after December 25, 1968, must, at a minimum, meet the 
applicable requirements of 49 CFR 571.108 (FMVSS No. 108) in effect at 
the time of manufacture of the vehicle. Commercial motor vehicles 
manufactured before December 25, 1968, must, at a minimum, meet the 
requirements of subpart B of part 393 in effect at the time of 
manufacture.
    (2) Exceptions: Pole trailers and trailer converter dollies must 
meet the part 393 requirements for lamps, reflective devices and 
electrical equipment in effect at the time of manufacture. Trailers 
which are equipped with conspicuity material which meets the 
requirements of Sec. 393.11(b) are not required to be equipped with the 
reflex reflectors listed in Table 1 if--
    (i) The conspicuity material is placed at the locations where reflex 
reflectors are required by Table 1; and
    (ii) The conspicuity material when installed on the motor vehicle 
meets the visibility requirements for the reflex reflectors.
    (b) Conspicuity Systems. Each trailer of 2,032 mm (80 inches) or 
more overall width, and with a GVWR over 4,536 kg (10,000 pounds), 
manufactured on or after December 1, 1993, except pole trailers and 
trailers designed exclusively for living or office use, shall be 
equipped with either retroreflective sheeting that meets the 
requirements of FMVSS No. 108 (S5.7.1), reflex reflectors that meet the 
requirements FMVSS No. 108 (S5.7.2), or a combination of retroreflective 
sheeting and reflex reflectors that meet the requirements of FMVSS No. 
108 (S5.7.3). The conspicuity system shall be installed and located as 
specified in FMVSS No. 108 [S5.7.1.4 (for retroreflective sheeting), 
S5.7.2.2 (for reflex reflectors), S5.7.3 (for a combination of sheeting 
and reflectors)] and have certification and markings as required by 
S5.7.1.5 (for retroreflective tape) and S5.7.2.3 (for reflex 
reflectors).
    (c) Prohibition on the use of amber stop lamps and tail lamps. No 
commercial motor vehicle may be equipped with an amber stop lamp, a tail 
lamp, or other lamp which is optically combined with an amber stop lamp 
or tail lamp.
    (d) Prohibition on the use of auxiliary lamps that supplement the 
identification lamps. No commercial motor vehicle may be equipped with 
lamps that are in a horizontal line with the required identification 
lamps unless those lamps are required by this regulation.

[[Page 371]]



                                          Table 1.--Required Lamps and Reflectors on Commercial Motor Vehicles
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                          Height above
                                                                                                            the road
                                                                                                           surface in
                                                                                                          millimeters
                                                                                                           (mm) (with
       Item on the vehicle         Quantity           Color               Location         Position      English units    Vehicles for which the devices
                                                                                                        in parenthesis)            are required
                                                                                                         measured from
                                                                                                         the center of
                                                                                                          the lamp at
                                                                                                          curb weight
--------------------------------------------------------------------------------------------------------------------------------------------------------
Headlamps........................         2  White..................  Front..........  On the front at  Not less than    A, B, C
                                                                                        the same         559 mm (22
                                                                                        height, with     inches) nor
                                                                                        an equal         more than
                                                                                        number at each   1,372 mm (54
                                                                                        side of the      inches).
                                                                                        vertical
                                                                                        center line as
                                                                                        far apart as
                                                                                        practicable.
Turn signal (front). See                  2  Amber..................  At or near the   One on each      Not less than    A, B, C
 footnotes <greek-i>2 and 12.                                          front.           side of the      381 mm (15
                                                                                        vertical         inches) nor
                                                                                        centerline at    more than
                                                                                        the same         2,108 mm (83
                                                                                        height and as    inches).
                                                                                        far apart as
                                                                                        practicable.
Identification lamps (front). See         3  Amber..................  Front..........  As close as      All three on     B, C
 footnote <greek-i>1.                                                                   practicable to   the same level
                                                                                        the top of the   as close as
                                                                                        vehicle, at      practicable to
                                                                                        the same         the top of the
                                                                                        height, and as   motor vehicle.
                                                                                        close as
                                                                                        practicable to
                                                                                        the vertical
                                                                                        centerline of
                                                                                        the vehicle
                                                                                        (or the
                                                                                        vertical
                                                                                        centerline of
                                                                                        the cab where
                                                                                        different from
                                                                                        the centerline
                                                                                        of the
                                                                                        vehicle) with
                                                                                        lamp centers
                                                                                        spaced not
                                                                                        less than 152
                                                                                        mm (6 inches)
                                                                                        or more than
                                                                                        305 mm (12
                                                                                        inches) apart.
                                                                                        Alternatively,
                                                                                        the front
                                                                                        lamps may be
                                                                                        located as
                                                                                        close as
                                                                                        practicable to
                                                                                        the top of the
                                                                                        cab.
Tail lamps. See footnotes <greek-         2  Red....................  Rear...........  One lamp on      Both on the      A, B, C, D, E, F, G, H
 i>5 and 11.                                                                            each side of     same level
                                                                                        the vertical     between 381 mm
                                                                                        centerline at    (15 inches)
                                                                                        the same         and 1,829 mm
                                                                                        height and as    (72 inches).
                                                                                        far apart as
                                                                                        practicable.
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 372]]


                                          Table 1.--Required Lamps and Reflectors on Commercial Motor Vehicles
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                          Height above
                                                                                                            the road
                                                                                                           surface in
                                                                                                          millimeters
                                                                                                           (mm) (with
       Item on the vehicle         Quantity           Color               Location         Position      English units    Vehicles for which the devices
                                                                                                        in parenthesis)            are required
                                                                                                         measured from
                                                                                                         the center of
                                                                                                          the lamp at
                                                                                                          curb weight
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stop lamps. See footnotes <greek-         2  Red....................  Rear...........  One lamp on      Both on the      A, B, C, D, E, F, G
 i>5 and 13.                                                                            each side of     same level
                                                                                        the vertical     between 381 mm
                                                                                        centerline at    (15 inches)
                                                                                        the same         and 1,829 mm
                                                                                        height and as    (72 inches).
                                                                                        far apart as
                                                                                        practicable.
Clearance lamps. See footnotes            2  Amber..................  One on each      One on each      Both on the      B, C, D, G, H
 <greek-i>8, 9, 10, 15 & 17.                                           side of the      side of the      same level as
                                                                       front of the     vertical         high as
                                                                       vehicle.         centerline to    practicable.
                                                                                        indicate
                                                                                        overall width.
                                          2  Red....................  One on each      One on each      Both on the      B, D, G, H
                                                                       side of the      side of the      same level as
                                                                       rear of the      vertical         high as
                                                                       vehicle.         centerline to    practicable.
                                                                                        indicate
                                                                                        overall width.
Reflex reflector, intermediate            2  Amber..................  One on each      At or near the   Between 381 mm   A, B, D, F, G
 (side).                                                               side.            midpoint         (15inches) and
                                                                                        between the      1,524 (60
                                                                                        front and rear   inches).
                                                                                        side marker
                                                                                        lamps, if the
                                                                                        length of the
                                                                                        vehicle is
                                                                                        more than
                                                                                        9,144 mm (30
                                                                                        feet).
Reflex reflector (rear). See              2  Red....................  Rear...........  One on each      Both on the      A, B, C, D, E, F, G
 footnotes <greek-i>5, 6, and 8.                                                        side of the      same level,
                                                                                        vertical         between 381 mm
                                                                                        centerline, as   (15 inches)
                                                                                        far apart as     and 1,524 mm
                                                                                        practicable      (60 inches).
                                                                                        and at the
                                                                                        same height.
Reflex reflector (rear side).....         2  Red....................  One on each      As far to the    Both on the      A, B, D, F, G
                                                                       side (rear).     rear as          same level,
                                                                                        practicable.     between 381 mm
                                                                                                         (15 inches)
                                                                                                         and 1,524 mm
                                                                                                         (60 inches).
Reflex reflector (front side).            2  Amber..................  One on each      As far to the    Between 381 mm   A, B, C, D, F, G
 See footnote <greek-i>16.                                             side (front).    front as         (15 inches)
                                                                                        practicable.     and 1,524 mm
                                                                                                         (60 inches).
License plate lamp (rear). See            1  White..................  At rear license                   No requirements  A, B, C, D, F, G
 footnote <greek-i>11.                                                 plate to
                                                                       illuminate the
                                                                       plate from the
                                                                       top or sides.
Side marker lamp (front). See             2  Amber..................  One on each      As far to the    Not less than    A, B, C, D, F
 footnote <greek-i>16.                                                 side.            front as         381 mm (15
                                                                                        practicable.     inches).

[[Page 373]]


Side marker lamp intermediate....         2  Amber..................  One on each      At or near the   Not less tan     A, B, D, F, G
                                                                       side.            midpoint         381 mm (15
                                                                                        between the      inches).
                                                                                        front and rear
                                                                                        side marker
                                                                                        lamps, if the
                                                                                        length of the
                                                                                        vehicle is
                                                                                        more than
                                                                                        9,144 mm (30
                                                                                        feet).
Side marker lamp (rear). See              2  Red....................  One on each      As far to the    Not less than    A, B, D, F, G
 footnotes <greek-i>4 and 8.                                           side.            rear as          381 mm (15
                                                                                        practicable.     inches), and
                                                                                                         on the rear of
                                                                                                         trailers not
                                                                                                         more than
                                                                                                         1,524 mm (60
                                                                                                         inches).
Turn signal (rear). See footnotes         2  Amber or red...........  Rear...........  One lamp on      Both on the      A, B, C, D, E, F, G
 <greek-i>5 and 12.                                                                     each side of     same level,
                                                                                        the vertical     between 381 mm
                                                                                        centerline as    (15 inches)
                                                                                        far apart as     and 2,108 mm
                                                                                        practicable.     (83 inches).
Identification lamp (rear). See           3  Red....................  Rear...........  One as close as  All three on     B, D, G
 footnotes <greek-i>3, 7, and 15.                                                       practicable to   the same level
                                                                                        the vertical     as close as
                                                                                        centerline.      practicable to
                                                                                        One on each      the top of the
                                                                                        side with lamp   vehicle.
                                                                                        centers spaced
                                                                                        not less than
                                                                                        152 mm (6
                                                                                        inches) or
                                                                                        more than 305
                                                                                        mm (12 inches)
                                                                                        apart.
Vehicular hazard warning signal           2  Amber..................  Front..........  One lamp on      Both on the      A, B, C
 flasher lamps. See footnotes                                                           each side of     same level,
 <greek-i>5 and 12.                                                                     the vertical     between 381 mm
                                                                                        centerline, as   (15 inches)
                                                                                        far apart as     and 2,108 mm
                                                                                        practicable.     (83 inches).
                                          2  Amber or red...........  Rear...........  One lamp on      Both on the      A, B, C, D, E, F, G
                                                                                        each side of     same level,
                                                                                        the vertical     between 381 mm
                                                                                        centerline, as   (15 inches)
                                                                                        far apart as     and 2,108 mm
                                                                                        practicable.     (83 inches).
Backup lamp. See footnote <greek-    1 or 2  White..................  Rear...........  Rear...........  No requirement.  A, B, C
 i>14.
Parking lamp.....................         2  Amber or white.........  Front..........  One lamp on      Both on the      A
                                                                                        each side of     same level,
                                                                                        the vertical     between 381 mm
                                                                                        centerline, as   (15 inches)
                                                                                        far apart as     and 2,108 mm
                                                                                        practicable.     (83 inches).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Legend: Types of commercial motor vehicles shown in the last column of Table 1.
A. Buses and trucks less than 2,032 mm (80 inches) in overall width.
B. Buses and trucks 2,032 mm (80 inches) or more in overall width.
C. Truck tractors.
D. Semitrailers and full trailers 2,032 mm (80 inches) or more in overall width except converter dollies.
E. Converter dolly.
F. Semitrailers and full trailers less than 2,032 mm (80 inches) in overall width.
G. Pole trailers.
H. Projecting loads.

Note: Lamps and reflectors may be combined as permitted by Sec. 393.22 and S5.4 of 49 CFR 571.108, Equipment combinations.
Footnote--1 Identification lamps may be mounted on the vertical centerline of the cab where different from the centerline of the vehicle, except where
  the cab is not more than 42 inches wide at the front roofline, then a single lamp at the center of the cab shall be deemed to comply with the
  requirements for identification lamps. No part of the identification lamps or their mountings may extend below the top of the vehicle windshield.

[[Page 374]]


Footnote--2 Unless the turn signals on the front are so constructed (double-faced) and located as to be visible to passing drivers, two turn signals are
  required on the rear of the truck tractor, one at each side as far apart as practicable.
Footnote--3 The identification lamps need not be visible or lighted if obscured by a vehicle in the same combination.
Footnote--4 Any semitrailer or full trailer manufactured on or after March 1, 1979, shall be equipped with rear side-marker lamps at a height of not
  less than 381 mm (15 inches), and on the rear of trailers not more than 1,524 mm (60 inches) above the road surface, as measured from the center of
  the lamp on the vehicle at curb weight.
Footnote--5 Each converter dolly, when towed singly by another vehicle and not as part of a full trailer, shall be equipped with one stop lamp, one tail
  lamp, and two reflectors (one on each side of the vertical centerline, as far apart as practicable) on the rear. Each converter dolly shall be
  equipped with rear turn signals and vehicular hazard warning signal flasher lamps when towed singly by another vehicle and not as part of a full
  trailer, if the converter dolly obscures the turn signals at the rear of the towing vehicle.
Footnote--6 Pole trailers shall be equipped with two reflex reflectors on the rear, one on each side of the vertical centerline as far apart as
  practicable, to indicate the extreme width of the trailer.
Footnote--7 Pole trailers, when towed by motor vehicles with rear identification lamps meeting the requirements of Sec. 393.11 and mounted at a height
  greater than the load being transported on the pole trailer, are not required to have rear identification lamps.
Footnote--8 Pole trailers shall have on the rearmost support for the load: (1) two front clearance lamps, one on each side of the vehicle, both on the
  same level and as high as practicable to indicate the overall width of the pole trailer; (2) two rear clearance lamps, one on each side of the
  vehicle, both on the same level and as high as practicable to indicate the overall width of the pole trailer; (3) two rear side marker lamps, one on
  each side of the vehicle, both on the same level, not less than 375 mm (15 inches) above the road surface; (4) two rear reflex reflectors, one on each
  side, both on the same level, not less than 375 mm (15 inches) above the road surface to indicate maximum width of the pole trailer; and (5) one red
  reflector on each side of the rearmost support for the load. Lamps and reflectors may be combined as allowed in Sec. 393.22.
Footnote--9 Any motor vehicle transporting a load which extends more than 102 mm (4 inches) beyond the overall width of the motor vehicle shall be
  equipped with the following lamps in addition to other required lamps when operated during the hours when headlamps are required to be used.
(1) The foremost edge of that portion of the load which projects beyond the side of the vehicle shall be marked (at its outermost extremity) with an
  amber lamp visible from the front and side.
(2) The rearmost edge of that portion of the load which projects beyond the side of the vehicle shall be marked (at its outermost extremity) with a red
  lamp visible from the rear and side.
(3) If the projecting load does not measure more than 914 mm (3 feet) from front to rear, it shall be marked with an amber lamp visible from the front,
  both sides, and rear, except that if the projection is located at or near the rear it shall be marked by a red lamp visible from front, side, and
  rear.
Footnote--10 Projections beyond rear of motor vehicles. Motor vehicles transporting loads which extend more than 1,219 mm (4 feet) beyond the rear of
  the motor vehicle, or which have tailboards or tailgates extending more than 1,219 mm (4 feet) beyond the body, shall have these projections marked as
  follows when the vehicle is operated during the hours when headlamps are required to be used:
(1) On each side of the projecting load, one red side marker lamp, visible from the side, located so as to indicate maximum overhang.
(2) On the rear of the projecting load, two red lamps, visible from the rear, one at each side; and two red reflectors visible from the rear, one at
  each side, located so as to indicate maximum width.
Footnote--11 To be illuminated when tractor headlamps are illuminated.
Footnote--12 Every bus, truck, and truck tractor shall be equipped with a signaling system that, in addition to signaling turning movements, shall have
  a switch or combination of switches that will cause the two front turn signals and the two rear signals to flash simultaneously as a vehicular traffic
  signal warning, required by Sec. 392-22(a). The system shall be capable of flashing simultaneously with the ignition of the vehicle on or off.
Footnote--13 To be actuated upon application of service brakes.
Footnote--14 Backup lamp required to operate when bus, truck, or truck tractor is in reverse.
Footnote--15
(1) For the purposes of Section 393.11, the term ``overall width'' refers to the nominal design dimension of the widest part of the vehicle, exclusive
  of the signal lamps, marker lamps, outside rearview mirrors, flexible fender extensions, and mud flaps.
(2) Clearance lamps may be mounted at a location other than on the front and rear if necessary to indicate the overall width of a vehicle, or for
  protection from damage during normal operation of the vehicle.
(3) On a trailer, the front clearance lamps may be mounted at a height below the extreme height if mounting at the extreme height results in the lamps
  failing to mark the overall width of the trailer.
(4) On a truck tractor, clearance lamps mounted on the cab may be located to indicate the width of the cab, rather than the width of the vehicle.
(5) When the rear identification lamps are mounted at the extreme height of a vehicle, rear clearance lamps are not required to be located as close as
  practicable to the top of the vehicle.
Footnote--16 A trailer subject to this part that is less than 1829 mm (6 feet) in overall length, including the trailer tongue, need not be equipped
  with front side marker lamps and front side reflex reflectors.
Footnote--17 A boat trailer subject to this part whose overall width is 2032 mm (80 inches) or more need not be equipped with both front and rear
  clearance lamps provided an amber (front) and red (rear) clearance lamp is located at or near the midpoint on each side so as to indicate its extreme
  width.


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[70 FR 48027, Aug. 15, 2005]

[[Page 387]]

Sec. 393.13  Retroreflective sheeting and reflex reflectors, 
          requirements for semitrailers and trailers manufactured before 
          December 1, 1993.

    (a) Applicability. All trailers and semitrailers manufactured prior 
to December 1, 1993, which have an overall width of 2,032 mm (80 inches) 
or more and a gross vehicle weight rating of 4,536 kg (10,001 pounds) or 
more, except trailers that are manufactured exclusively for use as 
offices or dwellings, pole trailers (as defined in Sec. 390.5 of this 
subchapter), and trailers transported in a driveaway-towaway operation, 
must be equipped with retroreflective sheeting or an array of reflex 
reflectors that meet the requirements of this section. Motor carriers 
operating trailers, other than container chassis (as defined in Sec. 
393.5), have until June 1, 2001, to comply with the requirements of this 
section. Motor carriers operating container chassis have until December 
1, 2001, to comply with the requirements of this section.
    (b) Retroreflective sheeting and reflex reflectors. Motor carriers 
are encouraged to retrofit their trailers with a conspicuity system that 
meets all of the requirements applicable to trailers manufactured on or 
after December 1, 1993, including the use of retroreflective sheeting or 
reflex reflectors in a red and white pattern (see Federal Motor Vehicle 
Safety Standard No. 108 (49 CFR 571.108), S5.7, Conspicuity systems). 
Motor carriers which do not retrofit their trailers to meet the 
requirements of FMVSS No. 108, for example by using an alternative color 
pattern, must comply with the remainder of this paragraph and with 
paragraph (c) or (d) of this section. Retroreflective sheeting or reflex 
reflectors in colors or color combinations other than red and white may 
be used on the sides or lower rear area of the semitrailer or trailer 
until June 1, 2009. The alternate color or color combination must be 
uniform along the sides and lower rear area of the trailer. The 
retroreflective sheeting or reflex reflectors on the upper rear area of 
the trailer must be white and conform to the requirements of FMVSS No. 
108 (S5.7). Red retroreflective sheeting or reflex reflectors shall not 
be used along the sides of the trailer unless it is used as part of a 
red and white pattern. Retroreflective sheeting shall have a width of at 
least 50 mm (2 inches).
    (c) Locations for retroreflective sheeting--(1) Sides. 
Retroreflective sheeting shall be applied to each side of the trailer or 
semitrailer. Each strip of retroreflective sheeting shall be positioned 
as horizontally as practicable, beginning and ending as close to the 
front and rear as practicable. The strip need not be continuous but the 
sum of the length of all of the segments shall be at least half of the 
length of the trailer and the spaces between the segments of the strip 
shall be distributed as evenly as practicable. The centerline for each 
strip of retroreflective sheeting shall be between 375 mm (15 inches) 
and 1,525 mm (60 inches) above the road surface when measured with the 
trailer empty or unladen, or as close as practicable to this area. If 
necessary to clear rivet heads or other similar obstructions, 50 mm (2 
inches) wide retroreflective sheeting may be separated into two 25 mm (1 
inch) wide strips of the same length and color, separated by a space of 
not more than 25 mm (1 inch).
    (2) Lower rear area. The rear of each trailer and semitrailer must 
be equipped with retroreflective sheeting. Each strip of retroreflective 
sheeting shall be positioned as horizontally as practicable, extending 
across the full width of the trailer, beginning and ending as close to 
the extreme edges as practicable. The centerline for each of the strips 
of retroreflective sheeting shall be between 375 mm (15 inches) and 
1,525 mm (60 inches) above the road surface when measured with the 
trailer empty or unladen, or as close as practicable to this area.
    (3) Upper rear area. Two pairs of white strips of retroreflective 
sheeting, each pair consisting of strips 300 mm (12 inches) long, must 
be positioned horizontally and vertically on the right and left upper 
corners of the rear of the body of each trailer and semitrailer, as 
close as practicable to the top of the trailer and as far apart as 
practicable. If the perimeter of the body, as viewed from the rear, is 
not square or rectangular, the strips may be applied along the 
perimeter, as close as practicable to the uppermost and outermost areas

[[Page 388]]

of the rear of the body on the left and right sides.
    (d) Locations for reflex reflectors.--(1) Sides. Reflex reflectors 
shall be applied to each side of the trailer or semitrailer. Each array 
of reflex reflectors shall be positioned as horizontally as practicable, 
beginning and ending as close to the front and rear as practicable. The 
array need not be continuous but the sum of the length of all of the 
array segments shall be at least half of the length of the trailer and 
the spaces between the segments of the strip shall be distributed as 
evenly as practicable. The centerline for each array of reflex 
reflectors shall be between 375 mm (15 inches) and 1,525 mm (60 inches) 
above the road surface when measured with the trailer empty or unladen, 
or as close as practicable to this area. The center of each reflector 
shall not be more than 100 mm (4 inches) from the center of each 
adjacent reflector in the segment of the array. If reflex reflectors are 
arranged in an alternating color pattern, the length of reflectors of 
the first color shall be as close as practicable to the length of the 
reflectors of the second color.
    (2) Lower rear area. The rear of each trailer and semitrailer must 
be equipped with reflex reflectors. Each array of reflex reflectors 
shall be positioned as horizontally as practicable, extending across the 
full width of the trailer, beginning and ending as close to the extreme 
edges as practicable. The centerline for each array of reflex reflectors 
shall be between 375 mm (15 inches) and 1,525 mm (60 inches) above the 
road surface when measured with the trailer empty or unladen, or as 
close as practicable to this area. The center of each reflector shall 
not be more than 100 mm (4 inches) from the center of each adjacent 
reflector in the segment of the array.
    (3) Upper rear area. Two pairs of white reflex reflector arrays, 
each pair at least 300 mm (12 inches) long, must be positioned 
horizontally and vertically on the right and left upper corners of the 
rear of the body of each trailer and semitrailer, as close as 
practicable to the top of the trailer and as far apart as practicable. 
If the perimeter of the body, as viewed from the rear, is not square or 
rectangular, the arrays may be applied along the perimeter, as close as 
practicable to the uppermost and outermost areas of the rear of the body 
on the left and right sides. The center of each reflector shall not be 
more than 100 mm (4 inches) from the center of each adjacent reflector 
in the segment of the array.

[64 FR 15605, Mar. 31, 1999, as amended at 66 FR 30339, June 6, 2001]

Sec. 393.17  Lamps and reflectors--combinations in driveaway-towaway 
          operation.

    A combination of motor vehicles engaged in driveaway-towaway 
operation must be equipped with operative lamps and reflectors 
conforming to the rules in this section.
    (a) The towing vehicle must be equipped as follows:
    (1) On the front, there must be at least two headlamps, an equal 
number at each side, two turn signals, one at each side, and two 
clearance lamps, one at each side.
    (2) On each side, there must be at least one side-marker lamp, 
located near the front of the vehicle.
    (3) On the rear, there must be at least two tail lamps, one at each 
side, and two stop lamps, one at each side.
    (b) Except as provided in paragraph (c) of this section, the 
rearmost towed vehicle of the combination (including the towed vehicle 
or a tow-bar combination, the towed vehicle of a single saddle-mount 
combination, and the rearmost towed vehicle of a double or triple 
saddle-mount combination) or, in the case of a vehicle full-mounted on a 
saddle-mount vehicle, either the full-mounted vehicle or the rearmost 
saddle-mounted vehicle must be equipped as follows:
    (1) On each side, there must be at least one side-marker lamp, 
located near the rear of the vehicle.
    (2) On the rear, there must be at least two tail lamps, two stop 
lamps, two turn signals, two clearance lamps, and two reflectors, one of 
each type at each side. In addition, if any vehicle in the combination 
is 80 inches or more in overall width, there must be three 
identification lamps on the rear.
    (c) If the towed vehicle in a combination is a mobile structure 
trailer, it must be equipped in accordance with

[[Page 389]]

the following lighting devices. For the purposes of this part, mobile 
structure trailer means a trailer that has a roof and walls, is at least 
10 feet wide, and can be used off road for dwelling or commercial 
purposes.
    (1) When the vehicle is operated in accordance with the terms of a 
special permit prohibiting operation during the times when lighted lamps 
are required under Sec. 392.30, it must have on the rear--
    (i) Two stop lamps, one on each side of the vertical centerline, at 
the same height, and as far apart as practicable;
    (ii) Two tail lamps, one on each side of the vertical centerline, at 
the same height, and as far apart as practicable;
    (iii) Two red reflex reflectors, one on each side of the vertical 
centerline, at the same height, and as far apart as practicable; and
    (iv) Two turn signal lamps, one on each side of the vertical 
centerline, at the same height, and as far apart as practicable.
    (2) At all other times, the vehicle must be equipped as specified in 
paragraph (b) of this section.
    (d) An intermediate towed vehicle in a combination consisting of 
more than two vehicles (including the first saddle-mounted vehicle of a 
double saddle-mount combination and the first and second saddle-mount 
vehicles of a triple saddle-mount combination) must have one side-marker 
lamp on each side, located near the rear of the vehicle.

[[Page 390]]

[GRAPHIC] [TIFF OMITTED] TR15AU05.017


[[Page 391]]


[GRAPHIC] [TIFF OMITTED] TR15AU05.018


[[Page 392]]


[GRAPHIC] [TIFF OMITTED] TR15AU05.019


(49 U.S.C. 304, 1655; 49 CFR 1.48(b) and 301.60)

[40 FR 36126, Aug. 19, 1975, as amended at 47 FR 47837, Oct. 28, 1982; 
70 FR 48044, Aug. 15, 2005]

Sec. 393.19  Hazard warning signals.

    The hazard warning signal operating unit on each commercial motor 
vehicle shall operate independently of the ignition or equivalent 
switch, and when activated, cause all turn signals required by Sec. 
393.11 to flash simultaneously.

[70 FR 48046, Aug. 15, 2005]

Sec. 393.20  [Reserved]

Sec. 393.22  Combination of lighting devices and reflectors.

    (a) Permitted combinations. Except as provided in paragraph (b) of 
this section, two or more lighting devices and reflectors (whether or 
not required by the rules in this part) may be combined optically if--
    (1) Each required lighting device and reflector conforms to the 
applicable rules in this part; and
    (2) Neither the mounting nor the use of a nonrequired lighting 
device or reflector impairs the effectiveness of a required lighting 
device or reflector or causes that device or reflector to be 
inconsistent with the applicable rules in this part.
    (b) Prohibited combinations. (1) A turn signal lamp must not be 
combined optically with either a head lamp or other

[[Page 393]]

lighting device or combination of lighting devices that produces a 
greater intensity of light than the turn signal lamp.
    (2) A turn signal lamp must not be combined optically with a stop 
lamp unless the stop lamp function is always deactivated when the turn 
signal function is activated.
    (3) A clearance lamp must not be combined optically with a tail lamp 
or identification lamp.

[39 FR 26908, July 24, 1974]

Sec. 393.23  Power supply for lamps.

    All required lamps must be powered by the electrical system of the 
motor vehicle with the exception of battery powered lamps used on 
projecting loads.

[70 FR 48046, Aug. 15, 2005]

Sec. 393.24  Requirements for head lamps, auxiliary driving lamps and 
          front fog lamps.

    (a) Headlamps. Every bus, truck and truck tractor shall be equipped 
with headlamps as required by Sec. 393.11(a). The headlamps shall 
provide an upper and lower beam distribution of light, selectable at the 
driver's will and be steady-burning. The headlamps shall be marked in 
accordance with FMVSS No. 108. Auxiliary driving lamps and/or front fog 
lamps may not be used to satisfy the requirements of this paragraph.
    (b) Auxiliary driving lamps and front fog lamps. Commercial motor 
vehicles may be equipped with auxiliary driving lamps and/or front fog 
lamps for use in conjunction with, but not in lieu of the required 
headlamps. Auxiliary driving lamps shall meet SAE Standard J581 
Auxiliary Upper Beam Lamps, July 2004, and front fog lamps shall meet 
SAE Standard J583 Front Fog Lamp, August 2004. (See Sec. 393.7 for 
information on the incorporation by reference and availability of these 
documents.)
    (c) Mounting. Headlamps shall be mounted and aimable in accordance 
with FMVSS No. 108. Auxiliary driving lamps and front fog lamps shall be 
mounted so that the beams are aimable and the mounting shall prevent the 
aim of the lighting device from being disturbed while the vehicle is 
operating on public roads.
    (d) Aiming. Headlamps, auxiliary driving lamps and front fog lamps 
shall be aimed to meet the aiming specifications in FMVSS No. 108 (49 
CFR 571.108), SAE J581, and SAE J583, respectively.

[70 FR 48046, Aug. 15, 2005]

Sec. 393.25  Requirements for lamps other than head lamps.

    (a) Mounting. All lamps shall be securely mounted on a rigid part of 
the vehicle. Temporary lamps must be securely mounted to the load and 
are not required to be mounted to a permanent part of the vehicle.
    (b) Visibility. Each lamp shall be located so that it meets the 
visibility requirements specified by FMVSS No. 108 in effect at the time 
of manufacture of the vehicle. Vehicles which were not subject to FMVSS 
No. 108 at the time of manufacture shall have each lamp located so that 
it meets the visibility requirements specified in the SAE standards 
listed in paragraph (c) of this section. If motor vehicle equipment 
(e.g., mirrors, snow plows, wrecker booms, backhoes, and winches) 
prevents compliance with this paragraph by any required lamp, an 
auxiliary lamp or device meeting the requirements of this paragraph 
shall be provided. This shall not be construed to apply to lamps on one 
unit which are obscured by another unit of a combination of vehicles.
    (c) Specifications. All required lamps (except marker lamps on 
projecting loads, lamps which are temporarily attached to vehicles 
transported in driveaway-towaway operations, and lamps on converter 
dollies and pole trailers) on vehicles manufactured on or after December 
25, 1968, shall, at a minimum, meet the applicable requirements of FMVSS 
No. 108 in effect on the date of manufacture of the vehicle. Marker 
lamps on projecting loads, all lamps which are temporarily attached to 
vehicles transported in driveaway-towaway operations, and all lamps on 
converter dollies and pole trailers must meet the following applicable 
SAE standards: J586--Stop Lamps for Use on Motor Vehicles Less Than 2032 
mm in Overall Width, March 2000; J2261 Stop

[[Page 394]]

Lamps and Front- and Rear-Turn Signal Lamps for Use on Motor Vehicles 
2032 mm or More in Overall Width, January 2002; J585--Tail Lamps (Rear 
Position Lamps) for Use on Motor Vehicles Less Than 2032 mm in Overall 
Width, March 2000; J588--Turn Signal Lamps for Use on Motor Vehicles 
Less Than 2032 mm in Overall Width, March 2000; J2040--Tail Lamps (Rear 
Position Lamps) for Use on Vehicles 2032 mm or More in Overall Width, 
March 2002; J592--Sidemarker Lamps for Use on Road Vehicles Less Than 
2032 mm in Overall Width, August 2000. (See Sec. 393.7 for information 
on the incorporation by reference and availability of these documents.)
    (d) (Reserved)
    (e) Lamps to be steady-burning. All exterior lamps (both required 
lamps and any additional lamps) shall be steady-burning with the 
exception of turn signal lamps; hazard warning signal lamps; school bus 
warning lamps; amber warning lamps or flashing warning lamps on tow 
trucks and commercial motor vehicles transporting oversized loads; and 
warning lamps on emergency and service vehicles authorized by State or 
local authorities. Lamps combined into the same shell or housing with a 
turn signal are not required to be steady burning while the turn signal 
is in use. Amber warning lamps must meet SAE J845--Optical Warning 
Devices for Authorized Emergency, Maintenance and Service Vehicles, May 
1997. Amber flashing warning lamps must meet SAE J595--Directional 
Flashing Optical Warning Devices for Authorized Emergency, Maintenance 
and Service Vehicles, January 2005. Amber gaseous discharge warning 
lamps must meet SAE J1318 Gaseous Discharge Warning Lamp for Authorized 
Emergency, Maintenance, and Service Vehicles, May 1998. (See Sec. 
393.7(b) for information on the incorporation by reference and 
availability of these documents.)
    (f) Stop lamp operation. The stop lamps on each vehicle shall be 
activated upon application of the service brakes. The stop lamps are not 
required to be activated when the emergency feature of the trailer 
brakes is used or when the stop lamp is optically combined with the turn 
signal and the turn signal is in use.

[70 FR 48047, Aug. 15, 2005]

Sec. 393.26  Requirements for reflectors.

    (a) Mounting. Reflex reflectors shall be mounted at the locations 
required by Sec. 393.11. In the case of motor vehicles so constructed 
that requirement for a 381 mm (15-inch) minimum height above the road 
surface is not practical, the reflectors shall be mounted as close as 
practicable to the required mounting height range. All permanent reflex 
reflectors shall be securely mounted on a rigid part of the vehicle. 
Temporary reflectors on projecting loads must be securely mounted to the 
load and are not required to be permanently mounted to a part of the 
vehicle. Temporary reflex reflectors on vehicles transported in 
driveaway-towaway operations must be firmly attached.
    (b) Specifications. All required reflex reflectors (except reflex 
reflectors on projecting loads, vehicles transported in a driveaway-
towaway operation, converter dollies and pole trailers) on vehicles 
manufactured on or after December 25, 1968, shall meet the applicable 
requirements of FMVSS No. 108 in effect on the date of manufacture of 
the vehicle. Reflex reflectors on projecting loads, vehicles transported 
in a driveaway-towaway operation, and all reflex reflectors on converter 
dollies and pole trailers must conform to SAE J594--Reflex Reflectors, 
December 2003.
    (c) Substitute material for side reflex reflectors. Reflective 
material conforming to ASTM D 4956-04, Standard Specification for 
Retroreflective Sheeting for Traffic Control, may be used in lieu of 
reflex reflectors if the material as used on the vehicle, meets the 
performance standards in either Table I of SAE J594 or Table IA of SAE 
J594--Reflex Reflectors, December 2003. (See Sec. 393.7(b) for 
information on the incorporation by reference and availability of these 
documents.)
    (d) Use of additional retroreflective surfaces. Additional 
retroreflective surfaces may be used in conjunction with, but not in 
lieu of the reflex reflectors required in subpart B of part 393, and the 
substitute material for side reflex reflectors allowed by paragraph (c) 
of this section, provided:

[[Page 395]]

    (1) Designs do not resemble traffic control signs, lights, or 
devices, except that straight edge striping resembling a barricade 
pattern may be used.
    (2) Designs do not tend to distort the length and/or width of the 
motor vehicle.
    (3) Such surfaces shall be at least 3 inches from any required lamp 
or reflector unless of the same color as such lamp or reflector.
    (4) No red color shall be used on the front of any motor vehicle, 
except for display of markings or placards required by Sec. 177.823 of 
this title.
    (5) Retroreflective license plates required by State or local 
authorities may be used.

[33 FR 19735, Dec. 25, 1968, as amended at 35 FR 3167, Feb. 19, 1970; 53 
FR 49397, Dec. 7, 1988; 70 FR 48047, Aug. 15, 2005]

Sec. 393.27  [Reserved]

Sec. 393.28  Wiring systems.

    Electrical wiring shall be installed and maintained to conform to 
SAE J1292--Automobile, Truck, Truck-Tractor, Trailer, and Motor Coach 
Wiring, October 1981, except the jumper cable plug and receptacle need 
not conform to SAE J560. The reference to SAE J1292 shall not be 
construed to require circuit protection on trailers. (See Sec. 393.7(b) 
for information on the incorporation by reference and availability of 
this document.)

[70 FR 48047, Aug. 15, 2005]

Sec. 393.29  [Reserved]

Sec. 393.30  Battery installation.

    Every storage battery on every vehicle, unless located in the engine 
compartment, shall be covered by a fixed part of the motor vehicle or 
protected by a removable cover or enclosure. Removable covers or 
enclosures shall be substantial and shall be securely latched or 
fastened. The storage battery compartment and adjacent metal parts which 
might corrode by reason of battery leakage shall be painted or coated 
with an acid-resisting paint or coating and shall have openings to 
provide ample battery ventilation and drainage. Wherever the cable to 
the starting motor passes through a metal compartment, the cable shall 
be protected against grounding by an acid and waterproof insulating 
bushing. Wherever a battery and a fuel tank are both placed under the 
driver's seat, they shall be partitioned from each other, and each 
compartment shall be provided with an independent cover, ventilation, 
and drainage.

Sec. 393.31--393.33  [Reserved]

                            Subpart C_Brakes

Sec. 393.40  Required brake systems.

    (a) Each commercial motor vehicle must have brakes adequate to stop 
and hold the vehicle or combination of motor vehicles. Each commercial 
motor vehicle must meet the applicable service, parking, and emergency 
brake system requirements provided in this section.
    (b) Service brakes. (1) Hydraulic brake systems. Motor vehicles 
equipped with hydraulic brake systems and manufactured on or after 
September 2, 1983, must, at a minimum, have a service brake system that 
meets the requirements of FMVSS No. 105 in effect on the date of 
manufacture. Motor vehicles which were not subject to FMVSS No. 105 on 
the date of manufacture must have a service brake system that meets the 
applicable requirements of Sec. Sec. 393.42, 393.48, 393.49, 393.51, 
and 393.52 of this subpart.
    (2) Air brake systems. Buses, trucks and truck-tractors equipped 
with air brake systems and manufactured on or after March 1, 1975, and 
trailers manufactured on or after January 1, 1975, must, at a minimum, 
have a service brake system that meets the requirements of FMVSS No. 121 
in effect on the date of manufacture. Motor vehicles which were not 
subject to FMVSS No. 121 on the date of manufacture must have a service 
brake system that meets the applicable requirements of Sec. Sec. 
393.42, 393.48, 393.49, 393.51, and 393.52 of this subpart.
    (3) Vacuum brake systems. Motor vehicles equipped with vacuum brake 
systems must have a service brake system that meets the applicable 
requirements of Sec. Sec. 393.42, 393.48, 393.49, 393.51, and 393.52 of 
this subpart.

[[Page 396]]

    (4) Electric brake systems. Motor vehicles equipped with electric 
brake systems must have a service brake system that meets the applicable 
requirements of Sec. Sec. 393.42, 393.48, 393.49 and 393.52 of this 
subpart.
    (c) Parking brakes. Each commercial motor vehicle must be equipped 
with a parking brake system that meets the applicable requirements of 
Sec. 393.41.
    (d) Emergency brakes--partial failure of service brakes.
    (1) Hydraulic brake systems. Motor vehicles manufactured on or after 
September 2, 1983, and equipped with a split service brake system must, 
at a minimum, meet the partial failure requirements of FMVSS No. 105 in 
effect on the date of manufacture.
    (2) Air brake systems. Buses, trucks and truck tractors manufactured 
on or after March 1, 1975, and trailers manufactured on or after January 
1, 1975, must be equipped with an emergency brake system which, at a 
minumum, meets the requirements of FMVSS No. 121 in effect on the date 
of manufacture.
    (3) Vehicles not subject to FMVSS Nos. 105 and 121 on the date of 
manufacture. Buses, trucks and truck tractors not subject to FMVSS Nos. 
105 or 121 on the date of manufacture must meet the requirements of 
Sec. 393.40(e). Trailers not subject to FMVSS No. 121 at the time of 
manufacture must meet the requirements of Sec. 393.43.
    (e) Emergency brakes, vehicles manufactured on or after July 1, 
1973. (1) A bus, truck, truck tractor, or a combination of motor 
vehicles manufactured on or after July 1, 1973, and not covered under 
paragraphs (d)(1) or (d)(2) of this section, must have an emergency 
brake system which consists of emergency features of the service brake 
system or an emergency system separate from the service brake system. 
The emergency brake system must meet the applicable requirements of 
Sec. Sec. 393.43 and 393.52.
    (2) A control by which the driver applies the emergency brake system 
must be located so that the driver can operate it from the normal 
seating position while restrained by any seat belts with which the 
vehicle is equipped. The emergency brake control may be combined with 
either the service brake control or the parking brake control. However, 
all three controls may not be combined.
    (f) Interconnected systems. (1) If the brake systems required by 
Sec. 393.40(a) are interconnected in any way, they must be designed, 
constructed, and maintained so that in the event of a failure of any 
part of the operating mechanism of one or more of the systems (except 
the service brake actuation pedal or valve), the motor vehicle will have 
operative brakes and, for vehicles manufactured on or after July 1, 
1973, be capable of meeting the requirements of Sec. 393.52(b).
    (2) A motor vehicle to which the requirements of FMVSS No. 105 
(S5.1.2), dealing with partial failure of the service brake, applied at 
the time of manufacture meets the requirements of Sec. 393.40(f)(1) if 
the motor vehicle is maintained in conformity with FMVSS No. 105 and the 
motor vehicle is capable of meeting the requirements of Sec. 393.52(b), 
except in the case of a structural failure of the brake master cylinder 
body.
    (3) A bus is considered to meet the requirements of Sec. 
393.40(f)(1) if it meets the requirements of Sec. 393.44 and Sec. 
393.52(b).

[70 FR 48048, Aug. 15, 2005]

Sec. 393.41  Parking brake system.

    (a) Hydraulic-braked vehicles manufactured on or after September 2, 
1983. Each truck and bus (other than a school bus) with a GVWR of 4,536 
kg (10,000 pounds) or less which is subject to this part and school 
buses with a GVWR greater than 4,536 kg (10,000 pounds) shall be 
equipped with a parking brake system as required by FMVSS No. 571.105 
(S5.2) in effect at the time of manufacture. The parking brake shall be 
capable of holding the vehicle or combination of vehicles stationary 
under any condition of loading in which it is found on a public road 
(free of ice and snow). Hydraulic-braked vehicles which were not subject 
to the parking brake requirements of FMVSS No. 571.105 (S5.2) must be 
equipped with a parking brake system that meets the requirements of 
paragraph (c) of this section.
    (b) Air-braked power units manufactured on or after March 1, 1975, 
and air-

[[Page 397]]

braked trailers manufactured on or after January 1, 1975.
    Each air-braked bus, truck and truck tractor manufactured on and 
after March 1, 1975, and each air-braked trailer except an agricultural 
commodity trailer, converter dolly, heavy hauler trailer or pulpwood 
trailer, shall be equipped with a parking brake system as required by 
FMVSS No. 121 (S5.6) in effect at the time of manufacture. The parking 
brake shall be capable of holding the vehicle or combination of vehicles 
stationary under any condition of loading in which it is found on a 
public road (free of ice and snow). An agricultural commodity trailer, 
heavy hauler or pulpwood trailer shall carry sufficient chocking blocks 
to prevent movement when parked.
    (c) Vehicles not subject to FMVSS Nos. 105 and 121 on the date of 
manufacture. (1) Each singly driven motor vehicle not subject to parking 
brake requirements of FMVSS Nos. 105 or 121 at the time of manufacturer, 
and every combination of motor vehicles must be equipped with a parking 
brake system adequate to hold the vehicle or combination on any grade on 
which it is operated, under any condition of loading in which it is 
found on a public road (free of ice and snow).
    (2) The parking brake system shall, at all times, be capable of 
being applied by either the driver's muscular effort or by spring 
action. If other energy is used to apply the parking brake, there must 
be an accumulation of that energy isolated from any common source and 
used exclusively for the operation of the parking brake.
    Exception: This paragraph shall not be applicable to air-applied, 
mechanically-held parking brake systems which meet the parking brake 
requirements of FMVSS No. 121 (S5.6).
    (3) The parking brake system shall be held in the applied position 
by energy other than fluid pressure, air pressure, or electric energy. 
The parking brake system shall not be capable of being released unless 
adequate energy is available to immediately reapply the parking brake 
with the required effectiveness.

[70 FR 48048, Aug. 15, 2005]

Sec. 393.42  Brakes required on all wheels.

    (a) Every commercial motor vehicle shall be equipped with brakes 
acting on all wheels.
    (b) Exception. (1) Trucks or truck tractors having three or more 
axles and manufactured before July 25, 1980, are not required to have 
brakes on the front wheels. However, these vehicles must meet the 
requirements of Sec. 393.52.
    (2) Motor vehicles being towed in a driveaway-towaway operation are 
not required to have operative brakes provided the combination of 
vehicles meets the requirements of Sec. 393.52. This exception is not 
applicable to:
    (i) Any motor vehicle towed by means of a tow-bar when another motor 
vehicle is full-mounted on the towed vehicle; and
    (ii) Any combination of motor vehicles utilizing three or more 
saddle-mounts.
    (3) Any semitrailer or pole trailer (laden or unladen) with a gross 
weight of 1,361 kg (3,000 pounds) or less which is subject to this part 
is not required to be equipped with brakes if the axle weight of the 
towed vehicle does not exceed 40 percent of the sum of the axle weights 
of the towing vehicle.
    (4) Any full trailer or four-wheel pole trailer (laden or unladen) 
with a gross weight of 1,361 kg (3,000 pounds) or less which is subject 
to this part is not required to be equipped with brakes if the sum of 
the axle weights of the towed vehicle does not exceed 40 percent of the 
sum of the axle weights of the towing vehicle.
    (5) Brakes are not required on the steering axle of a three-axle 
dolly which is steered by a co-driver.
    (6) Loaded housemoving dollies, specialized trailers and dollies 
used to transport industrial furnaces, reactors, and similar motor 
vehicles are not required to be equipped with brakes, provided the speed 
at which the combination of vehicles will be operated does not exceed 32 
km/hour (20 mph) and brakes on the combination of vehicles are capable 
of stopping the combination within 12.2 meters (40 feet) from the speed 
at which the vehicle is being operated or 32 km/hour (20 mph), whichever 
is less.

[[Page 398]]

[GRAPHIC] [TIFF OMITTED] TR15AU05.020


[52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 
FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 
1996; 70 FR 48049, Aug. 15, 2005]

Sec. 393.43  Breakaway and emergency braking.

    (a) Towing vehicle protection system. Every motor vehicle, if used 
to tow a trailer equipped with brakes, shall be equipped with a means 
for providing that in the case of a breakaway of the trailer, the 
service brakes on the towing vehicle will be capable of stopping the 
towing vehicle. For air braked towing units, the tractor protection 
valve or similar device shall operate automatically when the air 
pressure on the towing vehicle is between 138 kPa and 310 kPa (20 psi 
and 45 psi).
    (b) Emergency brake requirements, air brakes. Every truck or truck 
tractor equipped with air brakes, when used for towing other vehicles 
equipped with air brakes, shall be equipped with two means of activating 
the emergency features of the trailer brakes. One of these means shall 
operate automatically in the event of reduction of the towing vehicle 
air supply to a fixed pressure which shall not be lower than 20 pounds 
per square inch nor higher than 45 pounds per square inch. The other 
means shall be a manually controlled device readily operable by a person

[[Page 399]]

seated in the driving seat. Its emergency position or method of 
operation shall be clearly indicated. In no instance may the manual 
means be so arranged as to permit its use to prevent operation of the 
automatic means. The automatic and manual means required by this section 
may be, but are not required to be, separate.
    (c) Emergency brake requirements, vacuum brakes. Every truck tractor 
and truck when used for towing other vehicles equipped with vacuum 
brakes, shall have, in addition to the single control required by Sec. 
393.49 to operate all brakes of the combination, a second manual control 
device which can be used to operate the brakes on the towed vehicles in 
emergencies. Such second control shall be independent of brake air, 
hydraulic, and other pressure, and independent of other controls, unless 
the braking system be so arranged that failure of the pressure on which 
the second control depends will cause the towed vehicle brakes to be 
applied automatically. The second control is not required by this rule 
to provide modulated or graduated braking.
    (d) Breakaway braking requirements for trailers. Every trailer 
required to be equipped with brakes shall have brakes which apply 
automatically and immediately upon breakaway from the towing vehicle. 
With the exception of trailers having three or more axles, all brakes 
with which the trailer is required to be equipped must be applied upon 
breakaway from the towing vehicle. The brakes must remain in the applied 
position for at least 15 minutes.
    (e) Emergency valves. Air brake systems installed on towed vehicles 
shall be so designed, by the use of ``no-bleed-back'' relay emergency 
valves or equivalent devices, that the supply reservoir used to provide 
air for brakes shall be safeguarded against backflow of air to the 
towing vehicle upon reduction of the towing vehicle air pressure.
    (f) Exception. The requirements of paragraphs (b), (c) and (d) of 
this section shall not be applicable to commercial motor vehicles being 
transported in driveaway-towaway operations.

[53 FR 49384, Dec. 7, 1988, as amended at 70 FR 48050, Aug. 15, 2005]

Sec. 393.44  Front brake lines, protection.

    On every bus, if equipped with air brakes, the braking system shall 
be so constructed that in the event any brake line to any of the front 
wheels is broken, the driver can apply the brakes on the rear wheels 
despite such breakage. The means used to apply the brakes may be located 
forward of the driver's seat as long as it can be operated manually by 
the driver when the driver is properly restrained by any seat belt 
assembly provided for use. Every bus shall meet this requirement or 
comply with the regulations in effect at the time of its manufacture.

[53 FR 49400, Dec. 7, 1988]

Sec. 393.45  Brake tubing and hoses; hose assemblies and end fittings.

    (a) General construction requirements for tubing and hoses, 
assemblies, and end fittings. All brake tubing and hoses, brake hose 
assemblies, and brake hose end fittings must meet the applicable 
requirements of FMVSS No. 106 (49 CFR 571.106).
    (b) Brake tubing and hose installation. Brake tubing and hose must--
    (1) Be long and flexible enough to accommodate without damage all 
normal motions of the parts to which it is attached;
    (2) Be secured against chaffing, kinking, or other mechanical 
damage; and
    (3) Be installed in a manner that prevents it from contacting the 
vehicle's exhaust system or any other source of high temperatures.
    (c) Nonmetallic brake tubing. Coiled nonmetallic brake tubing may be 
used for connections between towed and towing motor vehicles or between 
the frame of a towed vehicle and the unsprung subframe of an adjustable 
axle of the motor vehicle if--
    (1) The coiled tubing has a straight segment (pigtail) at each end 
that is at least 51 mm (2 inches) in length and is encased in a spring 
guard or similar device which prevents the tubing from kinking at the 
fitting at which it is attached to the vehicle; and
    (2) The spring guard or similar device has at least 51 mm (2 inches) 
of closed coils or similar surface at its interface with the fitting and 
extends at least 38

[[Page 400]]

mm (1\1/2\ inches) into the coiled segment of the tubing from its 
straight segment.
    (d) Brake tubing and hose connections. All connections for air, 
vacuum, or hydraulic braking systems shall be installed so as to ensure 
an attachment free of leaks, constrictions or other conditions which 
would adversely affect the performance of the brake system.

[70 FR 48050, Aug. 15, 2005]

Sec. 393.46  [Reserved]

Sec. 393.47  Brake actuators, slack adjusters, linings/pads and drums/
          rotors.

    (a) General requirements. Brake components must be constructed, 
installed and maintained to prevent excessive fading and grabbing. The 
means of attachment and physical characteristics must provide for safe 
and reliable stopping of the commercial motor vehicle.
    (b) Brake chambers. The service brake chambers and spring brake 
chambers on each end of an axle must be the same size.
    (c) Slack adjusters. The effective length of the slack adjuster on 
each end of an axle must be the same.
    (d) Linings and pads. The thickness of the brake linings or pads 
shall meet the applicable requirements of this paragraph--
    (1) Steering axle brakes. The brake lining/pad thickness on the 
steering axle of a truck, truck-tractor or bus shall not be less than 
4.8 mm (\3/16\ inch) at the shoe center for a shoe with a continuous 
strip of lining; less than 6.4 mm (\1/4\ inch) at the shoe center for a 
shoe with two pads; or worn to the wear indicator if the lining is so 
marked, for air drum brakes. The steering axle brake lining/pad 
thickness shall not be less than 3.2 mm (\1/8\ inch) for air disc 
brakes, or 1.6 mm (\1/16\ inch) or less for hydraulic disc, drum and 
electric brakes.
    (2) Non-steering axle brakes. An air braked commercial motor vehicle 
shall not be operated with brake lining/pad thickness less than 6.4 mm 
(\1/4\ inch) or to the wear indicator if the lining is so marked 
(measured at the shoe center for drum brakes); or less than 3.2 mm (\1/
8\ inch) for disc brakes. Hydraulic or electric braked commercial motor 
vehicles shall not be operated with a lining/pad thickness less than 1.6 
mm (\1/16\ inch) (measured at the shoe center) for disc or drum brakes.
    (e) Clamp and Roto-Chamber Brake Actuator Readjustment limits. The 
pushrod travel for clamp and roto-chamber type actuators must be less 
than 80 percent of the rated strokes listed in SAE J1817--Long Stroke 
Air Brake Actuator Marking, July 2001 (See Sec. 393.7 (b) for 
information on incorporation by reference and availability of this 
document), or 80 percent of the rated stroke marked on the brake chamber 
by the chamber manufacturer, or the readjustment limit marked on the 
brake chamber by the chamber manufacturer. The pushrod travel for Type 
16 and 20 long stroke clamp type brake actuators must be less than 51 mm 
(2 inches) or 80 percent of the rated stroke marked on the brake chamber 
by the chamber manufacturer, or the readjustment limit marked on the 
brake chamber by the chamber manufacturer.
    (f) Wedge Brake Adjustment. The movement of the scribe mark on the 
lining shall not exceed 1.6 mm (\1/16\ inch).
    (g) Drums and rotors. The thickness of the drums or rotors shall not 
be less than the limits established by the brake drum or rotor 
manufacturer.

[70 FR 48051, Aug. 15, 2005]

Sec. 393.48  Brakes to be operative.

    (a) General rule. Except as provided in paragraphs (b) and (c) of 
this section, all brakes with which a commercial motor vehicle is 
equipped must be operable at all times.
    (b) Devices to reduce or remove front-wheel braking effort. A 
commercial motor vehicle may be equipped with a device to reduce the 
front wheel braking effort (or in the case of a three-axle truck or 
truck tractor manufactured before March 1, 1975, a device to remove the 
front-wheel braking effort) if that device meets the applicable 
requirements of paragraphs (b)(1) and (2) of this section.
    (1) Manually operated devices. Manually operated devices to reduce 
or remove front-wheel braking effort may only be used on buses, trucks, 
and truck tractors manufactured before March 1, 1975. Such devices must 
not be

[[Page 401]]

used unless the vehicle is being operated under adverse conditions such 
as wet, snowy, or icy roads.
    (2) Automatic devices. Automatic devices must not reduce the front-
wheel braking force by more than 50 percent of the braking force 
available when the automatic device is disconnected (regardless of 
whether or not an antilock system failure has occurred on any axle). The 
device must not be operable by the driver except upon application of the 
control that activates the braking system. The device must not be 
operable when the brake control application pressure exceeds 85 psig 
(for vehicles equipped with air brakes) or 85 percent of the maximum 
system pressure (for vehicles which are not equipped with air brakes).
    (c) Exception. Paragraph (a) of this section does not apply to--
    (1) A towed vehicle with disabling damage as defined in Sec. 390.5;
    (2) A vehicle which is towed in a driveaway-towaway operation and is 
included in the exemption to the requirement for brakes on all wheels, 
Sec. 393.42(b);
    (3) Unladen converter dollies with a gross weight of 1,361 kg (3,000 
lbs) or less, and manufactured prior to March 1, 1998;
    (4) The steering axle of a three-axle dolly which is steered by a 
co-driver;
    (5) Loaded house moving dollies, specialized trailers and dollies 
used to transport industrial furnaces, reactors, and similar motor 
vehicles provided the speed at which the combination of vehicles will be 
operated does not exceed 32 km/hour (20 mph) and brakes on the 
combination of vehicles are capable of stopping the combination within 
12.2 meters (40 feet) from the speed at which the vehicle is being 
operated or 32 km/hour (20 mph), whichever is less.
    (6) Raised lift axles. Brakes on lift axles need not be capable of 
being operated while the lift axle is raised. However, brakes on lift 
axles must be capable of being applied whenever the lift axle is lowered 
and the tires contact the roadway.

[70 FR 48051, Aug. 15, 2005]

Sec. 393.49  Single valve to operate all brakes.

    Every motor vehicle, the date of manufacture of which is subsequent 
to June 30, 1953, which is equipped with power brakes, shall have the 
braking system so arranged that one application valve shall when applied 
operate all the service brakes on the motor vehicle or combination of 
motor vehicles. This requirement shall not be construed to prohibit 
motor vehicles from being equipped with an additional valve to be used 
to operate the brakes on a trailer or trailers or as provided in Sec. 
393.44. This section shall not be applicable to driveaway-towaway 
operations unless the brakes on such operations are designed to be 
operated by a single valve.

Sec. 393.50  Reservoirs required.

    (a) Reservoir capacity for air-braked power units manufactured on or 
after March 1, 1975, and air-braked trailers manufactured on or after 
January 1, 1975. Buses, trucks, and truck-tractors manufactured on or 
after March 1, 1975, and air-braked trailers manufactured on or after 
January 1, 1975, must meet the reservoir requirements of FMVSS No. 121, 
S5.1.2, in effect on the date of manufacture.
    (b) Reservoir capacity for air-braked vehicles not subject to FMVSS 
No. 121 on the date of manufacture and all vacuum braked vehicles. Each 
motor vehicle using air or vacuum braking must have either reserve 
capacity, or a reservoir, that would enable the driver to make a full 
service brake application with the engine stopped without depleting the 
air pressure or vacuum below 70 percent of that indicated by the air or 
vacuum gauge immediately before the brake application is made. For the 
purposes of this paragraph, a full service brake application means 
depressing the brake pedal or treadle valve to the limit of its travel.
    (c) Safeguarding of air and vacuum. Each service reservoir system on 
a motor vehicle shall be protected against a loss of air pressure or 
vacuum due to a failure or leakage in the system between the service 
reservoir and the source of air pressure or vacuum, by check valves or 
equivalent devices whose proper functioning can be

[[Page 402]]

checked without disconnecting any air or vacuum line, or fitting.
    (d) Drain valves for air braked vehicles. Each reservoir must have a 
condensate drain valve that can be manually operated. Automatic 
condensate drain valves may be used provided (1) they may be operated 
manually, or (2) a manual means of draining the reservoirs is retained.

[70 FR 48052, Aug. 15, 2005]

Sec. 393.51  Warning signals, air pressure and vacuum gauges.

    (a) General Rule. Every bus, truck and truck tractor, except as 
provided in paragraph (f), must be equipped with a signal that provides 
a warning to the driver when a failure occurs in the vehicle's service 
brake system. The warning signal must meet the applicable requirements 
of paragraphs (b), (c), (d) or (e) of this section.
    (b) Hydraulic brakes. Vehicles manufactured on or after September 1, 
1975, must meet the brake system indicator lamp requirements of FMVSS 
No. 571.105 (S5.3) applicable to the vehicle on the date of manufacture. 
Vehicles manufactured on or after July 1, 1973 but before September 1, 
1975, or to which FMVSS No. 571.105 was not applicable on the date of 
manufacture, must have a warning signal which operates before or upon 
application of the brakes in the event of a hydraulic-type complete 
failure of a partial system. The signal must be either visible within 
the driver's forward field of view or audible. The signal must be 
continuous. (NOTE: FMVSS No. 105 was applicable to trucks and buses from 
September 1, 1975 to October 12, 1976, and from September 1, 1983, to 
the present. FMVSS No. 105 was not applicable to trucks and buses 
manufactured between October 12, 1976, and September 1, 1983. Motor 
carriers have the option of equipping those vehicles to meet either the 
indicator lamp requirements of FMVSS No. 105, or the indicator lamp 
requirements specified in this paragraph for vehicles which were not 
subject to FMVSS No. 105 on the date of manufacture.)
    (c) Air brakes. A commercial motor vehicle (regardless of the date 
of manufacture) equipped with service brakes activated by compressed air 
(air brakes) or a commercial motor vehicle towing a vehicle with service 
brakes activated by compressed air (air brakes) must be equipped with a 
pressure gauge and a warning signal. Trucks, truck tractors, and buses 
manufactured on or after March 1, 1975, must, at a minimum, have a 
pressure gauge and a warning signal which meets the requirements of 
FMVSS No. 121 (S5.1.4 for the pressure gauge and S5.1.5 for the warning 
signal) applicable to the vehicle on the date of manufacture of the 
vehicle. Power units to which FMVSS No. 571.121 was not applicable on 
the date of manufacture of the vehicle must be equipped with--
    (1) A pressure gauge, visible to a person seated in the normal 
driving position, which indicates the air pressure (in kilopascals (kPa) 
or pounds per square inch (psi)) available for braking; and
    (2) A warning signal that is audible or visible to a person in the 
normal driving position and provides a continuous warning to the driver 
whenever the air pressure in the service reservoir system is at 379 kPa 
(55 psi) and below, or one-half of the compressor governor cutout 
pressure, whichever is less.
    (d) Vacuum brakes. A commercial motor vehicle (regardless of the 
date it was manufactured) having service brakes activated by vacuum or a 
vehicle towing a vehicle having service brakes activated by vacuum must 
be equipped with--
    (1) A vacuum gauge, visible to a person seated in the normal driving 
position, which indicates the vacuum (in millimeters or inches of 
mercury) available for braking; and
    (2) A warning signal that is audible or visible to a person in the 
normal driving position and provides a continuous warning to the driver 
whenever the vacuum in the vehicle's supply reservoir is less than 203 
mm (8 inches) of mercury.
    (e) Hydraulic brakes applied or assisted by air or vacuum. Each 
vehicle equipped with hydraulically activated service brakes which are 
applied or assisted by compressed air or vacuum, and to which FMVSS No. 
105 was not applicable on the date of manufacture, must be equipped with 
a warning signal that

[[Page 403]]

conforms to paragraph (b) of this section for the hydraulic portion of 
the system; paragraph (c) of this section for the air assist/air applied 
portion; or paragraph (d) of this section for the vacuum assist/vacuum 
applied portion. This paragraph shall not be construed as requiring air 
pressure gauges or vacuum gauges, only warning signals.
    (f) Exceptions. The rules in paragraphs (c), (d) and (e) of this 
section do not apply to property carrying commercial motor vehicles 
which have less than three axles and (1) were manufactured before July 
1, 1973, and (2) have a manufacturer's gross vehicle weight rating less 
than 4,536 kg (10,001 pounds).

[70 FR 48052, Aug. 15, 2005]

Sec. 393.52  Brake performance.

    (a) Upon application of its service brakes, a motor vehicle or 
combination of motor vehicles must under any condition of loading in 
which it is found on a public highway, be capable of--
    (1) Developing a braking force at least equal to the percentage of 
its gross weight specified in the table in paragraph (d) of this 
section;
    (2) Decelerating to a stop from 20 miles per hour at not less than 
the rate specified in the table in paragraph (d) of this section; and
    (3) Stopping from 20 miles per hour in a distance, measured from the 
point at which movement of the service brake pedal or control begins, 
that is not greater than the distance specified in the table in 
paragraph (d) of this section; or, for motor vehicles or motor vehicle 
combinations that have a GVWR or GVW greater than 4,536 kg (10,000 
pounds),
    (4) Developing only the braking force specified in paragraph (a)(1) 
of this section and the stopping distance specified in paragraph (a)(3) 
of this section, if braking force is measured by a performance-based 
brake tester which meets the requirements of functional specifications 
for performance-based brake testers for commercial motor vehicles, where 
braking force is the sum of the braking force at each wheel of the 
vehicle or vehicle combination as a percentage of gross vehicle or 
combination weight.
    (b) Upon application of its emergency brake system and with no other 
brake system applied, a motor vehicle or combination of motor vehicles 
must, under any condition of loading in which it is found on a public 
highway, be capable of stopping from 20 miles per hour in a distance, 
measured from the point at which movement of the emergency brake control 
begins, that is not greater than the distance specified in the table in 
paragraph (d) of this section.
    (c) Conformity to the stopping-distance requirements of paragraphs 
(a) and (b) of this section shall be determined under the following 
conditions:
    (1) Any test must be made with the vehicle on a hard surface that is 
substantially level, dry, smooth, and free of loose material.
    (2) The vehicle must be in the center of a 12-foot-wide lane when 
the test begins and must not deviate from that lane during the test.
    (d) Vehicle brake performance table:

[[Page 404]]



----------------------------------------------------------------------------------------------------------------
                                                            Service brake systems                Emergency brake
                                             ---------------------------------------------------     systems
                                                                                                ----------------
                                               Braking force                    Application and  Application and
            Type of motor vehicle             as a percentage  Deceleration in      braking          braking
                                                  of gross     feet per second    distance in      distance in
                                                 vehicle or       per second       feet from        feet from
                                                combination                      initial speed    initial speed
                                                   weight                          at 20 mph        of 20 mph
----------------------------------------------------------------------------------------------------------------
A. Passenger-carrying vehicles:
    (1) Vehicles with a seating capacity of              65.2               21               20               54
     10 persons or less, including driver,
     and built on a passenger car chassis...
    (2) Vehicles with a seating capacity of              52.8               17               25               66
     more than 10 persons, including driver,
     and built on a passenger car chassis;
     vehicles built on a truck or bus
     chassis and having a manufacturer's
     GVWR of 10,000 pounds or less..........
    (3) All other passenger-carrying                     43.5               14               35               85
     vehicles...............................
B. Property-carrying vehicles:
    (1) Single unit vehicles having a                    52.8               17               25               66
     manufacturer's GVWR of 10,000 pounds or
     less...................................
    (2) Single unit vehicles having a                    43.5               14               35               85
     manufacturer's GVWR of more than 10,000
     pounds, except truck tractors.
     Combinations of a 2-axle towing vehicle
     and trailer having a GVWR of 3,000
     pounds or less. All combinations of 2
     or less vehicles in drive-away or tow-
     away operation.........................
    (3) All other property-carrying vehicles             43.5               14               40              90
     and combinations of property-carrying
     vehicles...............................
----------------------------------------------------------------------------------------------------------------
Notes: (a) There is a definite mathematical relationship between the figures in columns 2 and 3. If the
  decelerations set forth in column 3 are divided by 32.2 feet per-second per-second, the figures in column 2
  will be obtained. (For example, 21 divided by 32.2 equals 65.2 percent.) Column 2 is included in the
  tabulation because certain brake testing devices utilize this factor.
(b) The decelerations specified in column 3 are an indication of the effectiveness of the basic brakes, and as
  measured in practical brake testing are the maximum decelerations attained at some time during the stop. These
  decelerations as measured in brake tests cannot be used to compute the values in column 4 because the
  deceleration is not sustained at the same rate over the entire period of the stop. The deceleration increases
  from zero to a maximum during a period of brake system application and brake-force buildup. Also, other
  factors may cause the deceleration to decrease after reaching a maximum. The added distance that results
  because maximum deceleration is not sustained is included in the figures in column 4 but is not indicated by
  the usual brake-testing devices for checking deceleration.
(c) The distances in column 4 and the decelerations in column 3 are not directly related. ``Brake-system
  application and braking distance in feet'' (column 4) is a definite measure of the overall effectiveness of
  the braking system, being the distance traveled between the point at which the driver starts to move the
  braking controls and the point at which the vehicle comes to rest. It includes distance traveled while the
  brakes are being applied and distance traveled while the brakes are retarding the vehicle.
(d) The distance traveled during the period of brake-system application and brake-force buildup varies with
  vehicle type, being negligible for many passenger cars and greatest for combinations of commercial vehicles.
  This fact accounts for the variation from 20 to 40 feet in the values in column 4 for the various classes of
  vehicles.
(e) The terms ``GVWR'' and ``GVW'' refer to the manufacturer's gross vehicle weight rating and the actual gross
  vehicle weight, respectively.


[36 FR 20298, Oct. 20, 1971, as amended at 37 FR 5251, Mar. 11, 1972; 37 
FR 11336, June 7, 1972; 68 FR 51777, Aug. 9, 2002]

[[Page 405]]

Sec. 393.53  Automatic brake adjusters and brake adjustment indicators.

    (a) Automatic brake adjusters (hydraulic brake systems). Each 
commercial motor vehicle manufactured on or after October 20, 1993, and 
equipped with a hydraulic brake system, shall meet the automatic brake 
adjustment system requirements of Federal Motor Vehicle Safety Standard 
No. 105 (49 CFR 571.105, S5.1) applicable to the vehicle at the time it 
was manufactured.
    (b) Automatic brake adjusters (air brake systems). Each commercial 
motor vehicle manufactured on or after October 20, 1994, and equipped 
with an air brake system shall meet the automatic brake adjustment 
system requirements of Federal Motor Vehicle Safety Standard No. 121 (49 
CFR 571.121, S5.1.8) applicable to the vehicle at the time it was 
manufactured.
    (c) Brake adjustment indicator (air brake systems). On each 
commercial motor vehicle manufactured on or after October 20, 1994, and 
equipped with an air brake system which contains an external automatic 
adjustment mechanism and an exposed pushrod, the condition of service 
brake under-adjustment shall be displayed by a brake adjustment 
indicator conforming to the requirements of Federal Motor Vehicle Safety 
Standard No. 121 (49 CFR 571.121, S5.1.8) applicable to the vehicle at 
the time it was manufactured.

[60 FR 46245, Sept. 6, 1995]

Sec. 393.55  Antilock brake systems.

    (a) Hydraulic brake systems. Each truck and bus manufactured on or 
after March 1, 1999 (except trucks and buses engaged in driveaway-
towaway operations), and equipped with a hydraulic brake system, shall 
be equipped with an antilock brake system that meets the requirements of 
Federal Motor Vehicle Safety Standard (FMVSS) No. 105 (49 CFR 571.105, 
S5.5).
    (b) ABS malfunction indicators for hydraulic braked vehicles. Each 
hydraulic braked vehicle subject to the requirements of paragraph (a) of 
this section shall be equipped with an ABS malfunction indicator system 
that meets the requirements of FMVSS No. 105 (49 CFR 571.105, S5.3).
    (c) Air brake systems. (1) Each truck tractor manufactured on or 
after March 1, 1997 (except truck tractors engaged in driveaway-towaway 
operations), shall be equipped with an antilock brake system that meets 
the requirements of FMVSS No. 121 (49 CFR 571.121, S5.1.6.1(b)).
    (2) Each air braked commercial motor vehicle other than a truck 
tractor, manufactured on or after March 1, 1998 (except commercial motor 
vehicles engaged in driveaway-towaway operations), shall be equipped 
with an antilock brake system that meets the requirements of FMVSS No. 
121 (49 CFR 571.121, S5.1.6.1(a) for trucks and buses, S5.2.3 for 
semitrailers, converter dollies and full trailers).
    (d) ABS malfunction circuits and signals for air braked vehicles. 
(1) Each truck tractor manufactured on or after March 1, 1997, and each 
single-unit air braked vehicle manufactured on or after March 1, 1998, 
subject to the requirements of paragraph (c) of this section, shall be 
equipped with an electrical circuit that is capable of signaling a 
malfunction that affects the generation or transmission of response or 
control signals to the vehicle's antilock brake system (49 CFR 571.121, 
S5.1.6.2(a)).
    (2) Each truck tractor manufactured on or after March 1, 2001, and 
each single-unit vehicle that is equipped to tow another air-braked 
vehicle, subject to the requirements of paragraph (c) of this section, 
shall be equipped with an electrical circuit that is capable of 
transmitting a malfunction signal from the antilock brake system(s) on 
the towed vehicle(s) to the trailer ABS malfunction lamp in the cab of 
the towing vehicle, and shall have the means for connection of the 
electrical circuit to the towed vehicle. The ABS malfunction circuit and 
signal shall meet the requirements of FMVSS No. 121 (49 CFR 571.121, 
S5.1.6.2(b)).
    (3) Each semitrailer, trailer converter dolly, and full trailer 
manufactured on or after March 1, 2001, and subject to the requirements 
of paragraph (c)(2) of this section, shall be equipped with an 
electrical circuit that is capable of signaling a malfunction in the 
trailer's antilock brake system,

[[Page 406]]

and shall have the means for connection of this ABS malfunction circuit 
to the towing vehicle. In addition, each trailer manufactured on or 
after March 1, 2001, subject to the requirements of paragraph (c)(2) of 
this section, that is designed to tow another air-brake equipped trailer 
shall be capable of transmitting a malfunction signal from the antilock 
brake system(s) of the trailer(s) it tows to the vehicle in front of the 
trailer. The ABS malfunction circuit and signal shall meet the 
requirements of FMVSS No. 121 (49 CFR 571.121, S5.2.3.2).
    (e) Exterior ABS malfunction indicator lamps for trailers. Each 
trailer (including a trailer converter dolly) manufactured on or after 
March 1, 1998 and before March 1, 2009, and subject to the requirements 
of paragraph (c)(2) of this section, shall be equipped with an ABS 
malfunction indicator lamp which meets the requirements of FMVSS No. 121 
(49 CFR 571.121, S5.2.3.3).

[63 FR 24465, May 4, 1998]

                Subpart D_Glazing and Window Construction

Sec. 393.60  Glazing in specified openings.

    (a) Glazing material. Glazing material used in windshields, windows, 
and doors on a motor vehicle manufactured on or after December 25, 1968, 
shall at a minimum meet the requirements of Federal Motor Vehicle Safety 
Standard (FMVSS) No. 205 in effect on the date of manufacture of the 
motor vehicle. The glazing material shall be marked in accordance with 
FMVSS No. 205 (49 CFR 571.205, S6).
    (b) Windshields required. Each bus, truck and truck-tractor shall be 
equipped with a windshield. Each windshield or portion of a multi-piece 
windshield shall be mounted using the full periphery of the glazing 
material.
    (c) Windshield condition. With the exception of the conditions 
listed in paragraphs (c)(1), (c)(2), and (c)(3) of this section, each 
windshield shall be free of discoloration or damage in the area 
extending upward from the height of the top of the steering wheel 
(excluding a 51 mm (2 inch) border at the top of the windshield) and 
extending from a 25 mm (1 inch) border at each side of the windshield or 
windshield panel. Exceptions:
    (1) Coloring or tinting which meets the requirements of paragraph 
(d) of this section;
    (2) Any crack that is not intersected by any other cracks;
    (3) Any damaged area which can be covered by a disc 19 mm (\3/4\ 
inch) in diameter if not closer than 76 mm (3 inches) to any other 
similarly damaged area.
    (d) Coloring or tinting of windshields and windows. Coloring or 
tinting of windshields and the windows to the immediate right and left 
of the driver is allowed, provided the parallel luminous transmittance 
through the colored or tinted glazing is not less than 70 percent of the 
light at normal incidence in those portions of the windshield or windows 
which are marked as having a parallel luminous transmittance of not less 
than 70 percent. The transmittance restriction does not apply to other 
windows on the commercial motor vehicle.
    (e) Prohibition on obstructions to the driver's field of view--(1) 
Devices mounted at the top of the windshield. Antennas, transponders, 
and similar devices must not be mounted more than 152 mm (6 inches) 
below the upper edge of the windshield. These devices must be located 
outside the area swept by the windshield wipers, and outside the 
driver's sight lines to the road and highway signs and signals.
    (2) Decals and stickers mounted on the windshield. Commercial 
Vehicle Safety Alliance (CVSA) inspection decals, and stickers and/or 
decals required under Federal or State laws may be placed at the bottom 
or sides of the windshield provided such decals or stickers do not 
extend more than 115 mm (4\1/2\ inches) from the bottom of the 
windshield and are located outside the area swept by the windshield 
wipers, and outside the driver's sight lines to the road and highway 
signs or signals.

[63 FR 1387, Jan. 9, 1998]

Sec. 393.61  Truck and truck tractor window construction.

    Each truck and truck tractor (except trucks engaged in armored car 
service) shall have at least one window on each side of the driver's 
compartment. Each window must have a minimum area of

[[Page 407]]

1,290 cm\2\ (200 in\2\) formed by a rectangle 33 cm by 45 cm (13 inches 
by 17\3/4\ inches). The maximum radius of the corner arcs shall not 
exceed 152 mm (6 inches). The long axis of the rectangle shall not make 
an angle of more than 45 degrees with the surface on which the unladen 
vehicle stands. If the cab is designed with a folding door or doors or 
with clear openings where doors or windows are customarily located, no 
windows shall be required in those locations.

[70 FR 48052, Aug. 15, 2005]

Sec. 393.62  Emergency exits for buses.

    (a) Buses manufactured on or after September 1, 1994. Each bus with 
a GVWR of 4,536 kg (10,000 pounds) or less must meet the emergency exit 
requirements of FMVSS No. 217 (S5.2.2.3) in effect on the date of 
manufacture. Each bus with a GVWR of more than 4,536 kg (10,000 pounds) 
must have emergency exits which meet the applicable emergency exit 
requirements of FMVSS No. 217 (S5.2.2 or S5.2.3) in effect on the date 
of manufacture.
    (b) Buses manufactured on or after September 1, 1973, but before 
September 1, 1994. (1) Each bus (including a school bus used in 
interstate commerce for non-school bus operations) with a GVWR of more 
than 4,536 kg (10,000 lbs) must meet the requirements of FMVSS No. 217, 
S5.2.2 in effect on the date of manufacture.
    (2) Each bus (including a school bus used in interstate commerce for 
non-school bus operations) with a GVWR of 4,536 kg (10,000 lbs) or less 
must meet the requirements of FMVSS No. 217, S5.2.2.3 in effect on the 
date of manufacture.
    (c) Buses manufactured before September 1, 1973. For each seated 
passenger space provided, inclusive of the driver there shall be at 
least 432 cm\2\ (67 square inches) of glazing if such glazing is not 
contained in a push-out window; or, at least 432 cm\2\ (67 square 
inches) of free opening resulting from opening of a push-out type 
window. No area shall be included in this minimum prescribed area unless 
it will provide an unobstructed opening of at least 1,290 cm\2\ (200 
in\2\) formed by a rectangle 33 cm by 45 cm (13 inches by 17\3/4\ 
inches). The maximum radius of the corner arcs shall not exceed 152 mm 
(6 inches). The long axis of the rectangle shall not make an angle of 
more than 45 degrees with the surface on which the unladen vehicle 
stands. The area shall be measured either by removal of the glazing if 
not of the push-out type, or of the movable sash if of the push-out 
type. The exit must comply with paragraph (d) of this section. Each side 
of the bus must have at least 40 percent of emergency exit space 
required by this paragraph.
    (d) Laminated safety glass/push-out window requirements for buses 
manufactured before September 1, 1973. Emergency exit space used to 
satisfy the requirements of paragraph (c) of this section must have 
laminated safety glass or push-out windows designed and maintained to 
yield outward to provide a free opening.
    (1) Safety glass. Laminated safety glass must meet Test No. 25, 
Egress, of American National Standard for Safety Glazing Materials for 
Glazing Motor Vehicles and Motor Vehicle Equipment Operating on Land 
Highways--Safety Standards ANSI/SAE Z26.1/96, August 1997. (See Sec. 
393.7 (b) for information on incorporation by reference and availability 
of this document.)
    (2) Push-out windows. Each push-out window shall be releasable by 
operating no more than two mechanisms and allow manual release of the 
exit by a single occupant. For mechanisms which require rotary or 
straight (parallel to the undisturbed exit surface) motions to operate 
the exit, no more than 89 Newtons (20 pounds) of force shall be required 
to release the exit. For exits which require a straight motion 
perpendicular to the undisturbed exit surface, no more than 267 Newtons 
(60 pounds) shall be required to release the exit.
    (e) Emergency exit identification. Each bus and each school bus used 
in interstate commerce for non-school bus operations, manufactured on or 
after September 1, 1973, shall meet the applicable emergency exit 
identification or marking requirements of FMVSS No. 217, S5.5, in effect 
on the date of manufacture. The emergency exits and doors on all buses 
(including school buses used in interstate commerce for non-school bus 
operations) must be marked ``Emergency Exit'' or ``Emergency

[[Page 408]]

Door'' followed by concise operating instructions describing each motion 
necessary to unlatch or open the exit located within 152 mm (6 inches) 
of the release mechanism.
    (f) Exception for the transportation of prisoners. The requirements 
of this section do not apply to buses used exclusively for the 
transportation of prisoners.

[70 FR 48052, Aug. 15, 2005]

Sec. 393.63  [Reserved]

                         Subpart E_Fuel Systems

    Authority: Sec. 204, Interstate Commerce Act, as amended, 49 U.S.C. 
304; sec. 6, Department of Transportation Act, 49 U.S.C. 1655; 
delegation of authority at 49 CFR 1.48 and 389.4.

Sec. 393.65  All fuel systems.

    (a) Application of the rules in this section. The rules in this 
section apply to systems for containing and supplying fuel for the 
operation of motor vehicles or for the operation of auxiliary equipment 
installed on, or used in connection with, motor vehicles.
    (b) Location. Each fuel system must be located on the motor vehicle 
so that--
    (1) No part of the system extends beyond the widest part of the 
vehicle;
    (2) No part of a fuel tank is forward of the front axle of a power 
unit;
    (3) Fuel spilled vertically from a fuel tank while it is being 
filled will not contact any part of the exhaust or electrical systems of 
the vehicle, except the fuel level indicator assembly;
    (4) Fill pipe openings are located outside the vehicle's passenger 
compartment and its cargo compartment;
    (5) A fuel line does not extend between a towed vehicle and the 
vehicle that is towing it while the combination of vehicles is in 
motion; and
    (6) No part of the fuel system of a bus manufactured on or after 
January 1, 1973, is located within or above the passenger compartment.
    (c) Fuel tank installation. Each fuel tank must be securely attached 
to the motor vehicle in a workmanlike manner.
    (d) Gravity or syphon feed prohibited. A fuel system must not supply 
fuel by gravity or syphon feed directly to the carburetor or injector.
    (e) Selection control valve location. If a fuel system includes a 
selection control valve which is operable by the driver to regulate the 
flow of fuel from two or more fuel tanks, the valve must be installed so 
that either--
    (1) The driver may operate it while watching the roadway and without 
leaving his/her driving position; or
    (2) The driver must stop the vehicle and leave his/her seat in order 
to operate the valve.
    (f) Fuel lines. A fuel line which is not completely enclosed in a 
protective housing must not extend more than 2 inches below the fuel 
tank or its sump. Diesel fuel crossover, return, and withdrawal lines 
which extend below the bottom of the tank or sump must be protected 
against damage from impact. Every fuel line must be--
    (1) Long enough and flexible enough to accommodate normal movements 
of the parts to which it is attached without incurring damage; and
    (2) Secured against chafing, kinking, or other causes of mechanical 
damage.
    (g) Excess flow valve. When pressure devices are used to force fuel 
from a fuel tank, a device which prevents the flow of fuel from the fuel 
tank if the fuel feed line is broken must be installed in the fuel 
system.

[36 FR 15445, Aug. 14, 1971, as amended at 37 FR 4341, Mar. 2, 1972; 37 
FR 28752, Dec. 29, 1972]

Sec. 393.67  Liquid fuel tanks.

    (a) Application of the rules in this section. The rules in this 
section apply to tanks containing or supplying fuel for the operation of 
commercial motor vehicles or for the operation of auxiliary equipment 
installed on, or used in connection with commercial motor vehicles.
    (1) A liquid fuel tank manufactured on or after January 1, 1973, and 
a side-mounted gasoline tank must conform to all rules in this section.
    (2) A diesel fuel tank manufactured before January 1, 1973, and 
mounted on a bus must conform to the rules in paragraphs (c)(7)(iii) and 
(d)(2) of this section.
    (3) A diesel fuel tank manufactured before January 1, 1973, and 
mounted on

[[Page 409]]

a vehicle other than a bus must conform to the rules in paragraph 
(c)(7)(iii) of this section.
    (4) A gasoline tank, other than a side-mounted gasoline tank, 
manufactured before January 1, 1973, and mounted on a bus must conform 
to the rules in paragraphs (c) (1) through (10) and (d)(2) of this 
section.
    (5) A gasoline tank, other than a side-mounted gasoline tank, 
manufactured before January 1, 1973, and mounted on a vehicle other than 
a bus must conform to the rules in paragraphs (c) (1) through (10), 
inclusive, of this section.
    (6) Private motor carrier of passengers. Motor carriers engaged in 
the private transportation of passengers may continue to operate a 
commercial motor vehicle which was not subject to this section or 49 CFR 
571.301 at the time of its manufacture, provided the fuel tank of such 
vehicle is maintained to the original manufacturer's standards.
    (7) Motor vehicles that meet the fuel system integrity requirements 
of 49 CFR 571.301 are exempt from the requirements of this subpart, as 
they apply to the vehicle's fueling system.
    (b) Definitions. As used in this section--
    (1) The term liquid fuel tank means a fuel tank designed to contain 
a fuel that is liquid at normal atmospheric pressures and temperatures.
    (2) A side-mounted fuel tank is a liquid fuel tank which--
    (i) If mounted on a truck tractor, extends outboard of the vehicle 
frame and outside of the plan view outline of the cab; or
    (ii) If mounted on a truck, extends outboard of a line parallel to 
the longitudinal centerline of the truck and tangent to the outboard 
side of a front tire in a straight ahead position. In determining 
whether a fuel tank on a truck or truck tractor is side-mounted, the 
fill pipe is not considered a part of the tank.
    (c) Construction of liquid fuel tanks--(1) Joints. Joints of a fuel 
tank body must be closed by arc-, gas-, seam-, or spot-welding, by 
brazing, by silver soldering, or by techniques which provide heat 
resistance and mechanical securement at least equal to those 
specifically named. Joints must not be closed solely by crimping or by 
soldering with a lead-based or other soft solder.
    (2) Fittings. The fuel tank body must have flanges or spuds suitable 
for the installation of all fittings.
    (3) Threads. The threads of all fittings must be Dryseal American 
Standard Taper Pipe Thread or Dryseal SAE Short Taper Pipe Thread, 
specified in Society of Automotive Engineers Standard J476, as contained 
in the 1971 edition of the ``SAE Handbook,'' except that straight 
(nontapered) threads may be used on fittings having integral flanges and 
using gaskets for sealing. At least four full threads must be in 
engagement in each fitting.
    (4) Drains and bottom fittings. (i) Drains or other bottom fittings 
must not extend more than three-fourths of an inch below the lowest part 
of the fuel tank or sump.
    (ii) Drains or other bottom fittings must be protected against 
damage from impact.
    (iii) If a fuel tank has drains the drain fittings must permit 
substantially complete drainage of the tank.
    (iv) Drains or other bottom fittings must be installed in a flange 
or spud designed to accommodate it.
    (5) Fuel withdrawal fittings. Except for diesel fuel tanks, the 
fittings through which fuel is withdrawn from a fuel tank must be 
located above the normal level of fuel in the tank when the tank is 
full.
    (6) [Reserved]
    (7) Fill pipe. (i) Each fill pipe must be designed and constructed 
to minimize the risk of fuel spillage during fueling operations and when 
the vehicle is involved in a crash.
    (ii) For diesel-fueled vehicles, the fill pipe and vents of a fuel 
tank having a capacity of more than 94.75 L (25 gallons) of fuel must 
permit filling the tank with fuel at a rate of at least 75.8 L/m (20 
gallons per minute) without fuel spillage.
    (iii) For gasoline- and methanol-fueled vehicles with a GVWR of 
3,744 kg (8,500 pounds) or less, the vehicle must permit filling the 
tank with fuel dispensed at the applicable fill rate required by the 
regulations of the Environmental Protection Agency under 40 CFR 80.22.

[[Page 410]]

    (iv) For gasoline- and methanol-fueled vehicles with a GVWR of 
14,000 pounds (6,400 kg) or less, the vehicle must comply with the 
applicable fuel-spitback prevention and onboard refueling vapor recovery 
regulations of the Environmental Protection Agency under 40 CFR part 86.
    (v) Each fill pipe must be fitted with a cap that can be fastened 
securely over the opening in the fill pipe. Screw threads or a bayonet-
type point are methods of conforming to the requirements of paragraph 
(c) of this section.
    (8) Safety venting system. A liquid fuel tank with a capacity of 
more than 25 gallons of fuel must have a venting system which, in the 
event the tank is subjected to fire, will prevent internal tank pressure 
from rupturing the tank's body, seams, or bottom opening (if any).
    (9) Pressure resistance. The body and fittings of a liquid fuel tank 
with a capacity of more than 25 gallons of fuel must be capable of 
withstanding an internal hydrostatic pressure equal to 150 percent of 
the maximum internal pressure reached in the tank during the safety 
venting systems test specified in paragraph (d)(1) of this section.
    (10) Air vent. Each fuel tank must be equipped with a nonspill air 
vent (such as a ball check). The air vent may be combined with the fill-
pipe cap or safety vent, or it may be a separate unit installed on the 
fuel tank.
    (11) Markings. If the body of a fuel tank is readily visible when 
the tank is installed on the vehicle, the tank must be plainly marked 
with its liquid capacity. The tank must also be plainly marked with a 
warning against filling it to more than 95 percent of its liquid 
capacity.
    (12) Overfill restriction. A liquid fuel tank manufactured on or 
after January 1, 1973, must be designed and constructed so that--
    (i) The tank cannot be filled, in a normal filling operation, with a 
quantity of fuel that exceeds 95 percent of the tank's liquid capacity; 
and
    (ii) When the tank is filled, normal expansion of the fuel will not 
cause fuel spillage.
    (d) Liquid fuel tank tests. Each liquid fuel tank must be capable of 
passing the tests specified in paragraphs (d)(1) and (2) of this 
section. The specified tests are a measure of performance only. 
Alternative procedures which assure that equipment meets the required 
performance standards may be used. .
    (1) Safety venting system test--(i) Procedure. Fill the tank three-
fourths full with fuel, seal the fuel feed outlet, and invert the tank. 
When the fuel temperature is between 50 [deg]F. and 80 [deg]F., apply an 
enveloping flame to the tank so that the temperature of the fuel rises 
at a rate of not less than 6 [deg]F. and not more than 8 [deg]F. per 
minute.
    (ii) Required performance. The safety venting system required by 
paragraph (c)(8) of this section must activate before the internal 
pressure in the tank exceeds 50 pounds per square inch, gauge, and the 
internal pressure must not thereafter exceed the pressure at which the 
system activated by more than five pounds per square inch despite any 
further increase in the temperature of the fuel.
    (2) Leakage test--(i) Procedure. Fill the tank to capacity with fuel 
having a temperature between 50 [deg]F. and 80 [deg]F. With the fill-
pipe cap installed, turn the tank through an angle of 150[deg] in any 
direction about any axis from its normal position.
    (ii) Required performance. Neither the tank nor any fitting may leak 
more than a total of one ounce by weight of fuel per minute in any 
position the tank assumes during the test.
    (e) Side-mounted liquid fuel tank tests. Each side-mounted liquid 
fuel tank must be capable of passing the tests specified in paragraphs 
(e)(1) and (2) of this section and the test specified in paragraphs 
(d)(1) and (2) of this section. The specified tests are a measure of 
performance only. Alternative procedures which assure that equipment 
meets the required performance criteria may be used.
    (1) Drop test--(i) Procedure. Fill the tank with a quantity of water 
having a weight equal to the weight of the maximum fuel load of the tank 
and drop the tank 30 feet onto an unyielding surface so that it lands 
squarely on one corner.
    (ii) Required performance. Neither the tank nor any fitting may leak 
more

[[Page 411]]

than a total of 1 ounce by weight of water per minute.
    (2) Fill-pipe test--(i) Procedure. Fill the tank with a quantity of 
water having a weight equal to the weight of the maximum fuel load of 
the tank and drop the tank 10 feet onto an unyielding surface so that it 
lands squarely on its fill-pipe.
    (ii) Required performance. Neither the tank nor any fitting may leak 
more than a total of 1 ounce by weight of water per minute.
    (f) Certification and markings. Each liquid fuel tank shall be 
legibly and permanently marked by the manufacturer with the following 
minimum information:
    (1) The month and year of manufacture,
    (2) The manufacturer's name on tanks manufactured on and after July 
1, 1989, and means of identifying the facility at which the tank was 
manufactured, and
    (3) A certificate that it conforms to the rules in this section 
applicable to the tank. The certificate must be in the form set forth in 
either of the following:
    (i) If a tank conforms to all rules in this section pertaining to 
side-mounted fuel tanks: ``Meets all FMCSA side-mounted tank 
requirements.''
    (ii) If a tank conforms to all rules in this section pertaining to 
tanks which are not side-mounted fuel tanks: ``Meets all FMCSA 
requirements for non-side-mounted fuel tanks.''
    (iii) The form of certificate specified in paragraph (f)(3) (i) or 
(ii) of this section may be used on a liquid fuel tank manufactured 
before July 11, 1973, but it is not mandatory for liquid fuel tanks 
manufactured before March 7, 1989. The form of certification 
manufactured on or before March 7, 1989, must meet the requirements in 
effect at the time of manufacture.
    (4) Exception. The following previously exempted vehicles are not 
required to carry the certification and marking specified in paragraphs 
(f)(1) through (3) of this section:
    (i) Ford vehicles with GVWR over 10,000 pounds identified as 
follows: The vehicle identification numbers (VINs) contain A, K, L, M, 
N, W, or X in the fourth position.
    (ii) GM G-Vans (Chevrolet Express and GMC Savanna) and full-sized C/
K trucks (Chevrolet Silverado and GMC Sierra) with GVWR over 10,000 
pounds identified as follows: The VINs contain either a ``J'' or a ``K'' 
in the fourth position. In addition, the seventh position of the VINs on 
the G-Van will contain a ``1.''

[36 FR 15445, Aug. 14, 1971, as amended at 37 FR 4341, Mar. 2, 1972; 37 
FR 28753, Dec. 29, 1972; 45 FR 46424, July 10, 1980; 53 FR 49400, Dec. 
7, 1988; 59 FR 8753, Feb. 23, 1994; 69 FR 31305, June 3, 2004; 70 FR 
48053, Aug. 15, 2005]

Sec. 393.68  Compressed natural gas fuel containers.

    (a) Applicability. The rules in this section apply to compressed 
natural gas (CNG) fuel containers used for supplying fuel for the 
operation of commercial motor vehicles or for the operation of auxiliary 
equipment installed on, or used in connection with commercial motor 
vehicles.
    (b) CNG containers manufactured on or after March 26, 1995. Any 
motor vehicle manufactured on or after March 26, 1995, and equipped with 
a CNG fuel tank must meet the CNG container requirements of FMVSS No. 
304 (49 CFR 571.304) in effect at the time of manufacture of the 
vehicle.
    (c) Labeling. Each CNG fuel container shall be permanently labeled 
in accordance with the requirements of FMVSS No. 304, S7.4.

[70 FR 48053, Aug. 15, 2005]

Sec. 393.69  Liquefied petroleum gas systems.

    (a) A fuel system that uses liquefied petroleum gas as a fuel for 
the operation of a motor vehicle or for the operation of auxiliary 
equipment installed on, or used in connection with, a motor vehicle must 
conform to the ``Standards for the Storage and Handling of Liquefied 
Petroleum Gases'' of the National Fire Protection Association, Battery 
March Park, Quincy, MA 02269, as follows:
    (1) A fuel system installed before December 31, 1962, must conform 
to the 1951 edition of the Standards.
    (2) A fuel system installed on or after December 31, 1962, and 
before January 1, 1973, must conform to Division IV of the June 1959 
edition of the Standards.

[[Page 412]]

    (3) A fuel system installed on or after January 1, 1973, and 
providing fuel for propulsion of the motor vehicle must conform to 
Division IV of the 1969 edition of the Standards.
    (4) A fuel system installed on or after January 1, 1973, and 
providing fuel for the operation of auxiliary equipment must conform to 
Division VII of the 1969 edition of the Standards.
    (b) When the rules in this section require a fuel system to conform 
to a specific edition of the Standards, the fuel system may conform to 
the applicable provisions in a later edition of the Standards specified 
in this section.
    (c) The tank of a fuel system must be marked to indicate that the 
system conforms to the Standards.

[36 FR 15445, Aug. 14, 1971, as amended at 37 FR 4342, Mar. 2, 1972; 41 
FR 53031, Dec. 3, 1976; 53 FR 49400, Dec. 7, 1988]

              Subpart F_Coupling Devices and Towing Methods

Sec. 393.70  Coupling devices and towing methods, except for driveaway-
          towaway operations.

    (a) Tracking. When two or more vehicles are operated in combination, 
the coupling devices connecting the vehicles shall be designed, 
constructed, and installed, and the vehicles shall be designed and 
constructed, so that when the combination is operated in a straight line 
on a level, smooth, paved surface, the path of the towed vehicle will 
not deviate more than 3 inches to either side of the path of the vehicle 
that tows it.
    (b) Fifth wheel assemblies--(1) Mounting--(i) Lower half. The lower 
half of a fifth wheel mounted on a truck tractor or converter dolly must 
be secured to the frame of that vehicle with properly designed brackets, 
mounting plates or angles and properly tightened bolts of adequate size 
and grade, or devices that provide equivalent security. The installation 
shall not cause cracking, warping, or deformation of the frame. The 
installation must include a device for positively preventing the lower 
half of the fifth wheel from shifting on the frame to which it is 
attached.
    (ii) Upper half. The upper half of a fifth wheel must be fastened to 
the motor vehicle with at least the same security required for the 
installation of the lower half on a truck tractor or converter dolly.
    (2) Locking. Every fifth wheel assembly must have a locking 
mechanism. The locking mechanism, and any adapter used in conjunction 
with it, must prevent separation of the upper and lower halves of the 
fifth wheel assembly unless a positive manual release is activated. The 
release may be located so that the driver can operate it from the cab. 
If a motor vehicle has a fifth wheel designed and constructed to be 
readily separable, the fifth wheel locking devices shall apply 
automatically on coupling.
    (3) Location. The lower half of a fifth wheel shall be located so 
that, regardless of the condition of loading, the relationship between 
the kingpin and the rear axle or axles of the towing motor vehicle will 
properly distribute the gross weight of both the towed and towing 
vehicles on the axles of those vehicles, will not unduly interfere with 
the steering, braking, and other maneuvering of the towing vehicle, and 
will not otherwise contribute to unsafe operation of the vehicles 
comprising the combination. The upper half of a fifth wheel shall be 
located so that the weight of the vehicles is properly distributed on 
their axles and the combination of vehicles will operate safely during 
normal operation.
    (c) Towing of full trailers. A full trailer must be equipped with a 
tow-bar and a means of attaching the tow-bar to the towing and towed 
vehicles. The tow-bar and the means of attaching it must--
    (1) Be structurally adequate for the weight being drawn;
    (2) Be properly and securely mounted;
    (3) Provide for adequate articulation at the connection without 
excessive slack at that location; and
    (4) Be provided with a locking device that prevents accidental 
separation of the towed and towing vehicles. The mounting of the trailer 
hitch (pintle hook or equivalent mechanism) on the towing vehicle must 
include reinforcement or bracing of the frame sufficient to produce 
strength and rigidity of the frame to prevent its undue distortion.

[[Page 413]]

    (d) Safety devices in case of tow-bar failure or disconnection. 
Every full trailer and every converter dolly used to convert a 
semitrailer to a full trailer must be coupled to the frame, or an 
extension of the frame, of the motor vehicle which tows it with one or 
more safety devices to prevent the towed vehicle from breaking loose in 
the event the tow-bar fails or becomes disconnected. The safety device 
must meet the following requirements:
    (1) The safety device must not be attached to the pintle hook or any 
other device on the towing vehicle to which the tow-bar is attached. 
However, if the pintle hook or other device was manufactured prior to 
July 1, 1973, the safety device may be attached to the towing vehicle at 
a place on a pintle hook forging or casting if that place is independent 
of the pintle hook.
    (2) The safety device must have no more slack than is necessary to 
permit the vehicles to be turned properly.
    (3) The safety device, and the means of attaching it to the 
vehicles, must have an ultimate strength of not less than the gross 
weight of the vehicle or vehicles being towed.
    (4) The safety device must be connected to the towed and towing 
vehicles and to the tow-bar in a manner which prevents the tow-bar from 
dropping to the ground in the event it fails or becomes disconnected.
    (5) Except as provided in paragraph (d)(6) of this section, if the 
safety device consists of safety chains or cables, the towed vehicle 
must be equipped with either two safety chains or cables or with a 
bridle arrangement of a single chain or cable attached to its frame or 
axle at two points as far apart as the configuration of the frame or 
axle permits. The safety chains or cables shall be either two separate 
pieces, each equipped with a hook or other means for attachment to the 
towing vehicle, or a single piece leading along each side of the tow-bar 
from the two points of attachment on the towed vehicle and arranged into 
a bridle with a single means of attachment to be connected to the towing 
vehicle. When a single length of cable is used, a thimble and twin-base 
cable clamps shall be used to form the forward bridle eye. The hook or 
other means of attachment to the towing vehicle shall be secured to the 
chains or cables in a fixed position.
    (6) If the towed vehicle is a converter dolly with a solid tongue 
and without a hinged tow-bar or other swivel between the fifth wheel 
mounting and the attachment point of the tongue eye or other hitch 
device--
    (i) Safety chains or cables, when used as the safety device for that 
vehicle, may consist of either two chains or cables or a single chain or 
cable used alone;
    (ii) A single safety device, including a single chain or cable used 
alone as the safety device, must be in line with the centerline of the 
trailer tongue; and
    (iii) The device may be attached to the converter dolly at any point 
to the rear of the attachment point of the tongue eye or other hitch 
device.
    (7) Safety devices other than safety chains or cables must provide 
strength, security of attachment, and directional stability equal to, or 
greater than, safety chains or cables installed in accordance with 
paragraphs (d) (5) and (6) of this section.
    (8)(i) When two safety devices, including two safety chains or 
cables, are used and are attached to the towing vehicle at separate 
points, the points of attachment on the towing vehicle shall be located 
equally distant from, and on opposite sides of, the longitudinal 
centerline of the towing vehicle.
    (ii) Where two chains or cables are attached to the same point on 
the towing vehicle, and where a bridle or a single chain or cable is 
used, the point of attachment must be on the longitudinal centerline or 
within 152 mm (6 inches) to the right of the longitudinal centerline of 
the towing vehicle.
    (iii) A single safety device, other than a chain or cable, must also 
be attached to the towing vehicle at a point on the longitudinal 
centerline or within 152 mm (6 inches) to the right of the longitudinal 
centerline of the towing vehicle.

[37 FR 21439, Oct. 11, 1972, as amended at 70 FR 48053, Aug. 15, 2005]

[[Page 414]]

Sec. 393.71  Coupling devices and towing methods, driveaway-towaway 
          operations.

    (a) Number in combination. (1) No more than three saddle-mounts may 
be used in any combination.
    (2) No more than one tow-bar or ball-and-socket type coupling device 
may be used in any combination.
    (3) When motor vehicles are towed by means of triple saddle-mounts, 
the towed vehicles shall have brakes acting on all wheels which are in 
contact with the roadway.
    (b) Carrying vehicles on towing vehicle. (1) When adequately and 
securely attached by means equivalent in security to that provided in 
paragraph (j)(2) of this section, a motor vehicle or motor vehicles may 
be full-mounted on the structure of a towing vehicle engaged in any 
driveaway-towaway operation.
    (2) No motor vehicle or motor vehicles may be full-mounted on a 
towing vehicle unless the relationship of such full-mounted vehicles to 
the rear axle or axles results in proper distribution of the total gross 
weight of the vehicles and does not unduly interfere with the steering, 
braking, or maneuvering of the towing vehicle, or otherwise contribute 
to the unsafe operation of the vehicles comprising the combination.
    (3) Saddle-mounted vehicles must be arranged such that the gross 
weight of the vehicles is properly distributed to prevent undue 
interference with the steering, braking, or maneuvering of the 
combination of vehicles.
    (c) Carrying vehicles on towed vehicles. (1) When adequately and 
securely attached by means equivalent in security to that provided in 
paragraph (j)(2) of this section, a motor vehicle or motor vehicles may 
be full-mounted on the structure of towed vehicles engaged in any 
driveaway-towaway operation.
    (2) No motor vehicle shall be full-mounted on a motor vehicle towed 
by means of a tow-bar unless the towed vehicle is equipped with brakes 
and is provided with means for effective application of brakes acting on 
all wheels and is towed on its own wheels.
    (3) No motor vehicle or motor vehicles shall be full-mounted on a 
motor vehicle towed by means of a saddle-mount unless the center line of 
the kingpin or equivalent means of attachment of such towed vehicle 
shall be so located on the towing vehicle that the relationship to the 
rear axle or axles results in proper distribution of the total gross 
weight of the vehicles and does not unduly interfere with the steering, 
braking, or maneuvering of the towing vehicle or otherwise contribute to 
the unsafe operation of vehicles comprising the combination; and unless 
a perpendicular to the ground from the center of gravity of the full-
mounted vehicles lies forward of the center line of the rear axle of the 
saddle-mounted vehicle.
    (4) If a motor vehicle towed by means of a double saddle-mount has 
any vehicle full-mounted on it, such saddle-mounted vehicle shall at all 
times while so loaded have effective brakes acting on those wheels which 
are in contact with the roadway.
    (d) Bumper tow-bars on heavy vehicles prohibited. Tow-bars of the 
type which depend upon the bumpers as a means of transmitting forces 
between the vehicles shall not be used to tow a motor vehicle weighing 
more than 5,000 pounds.
    (e) Front wheels of saddle-mounted vehicles restrained. A motor 
vehicle towed by means of a saddle-mount shall have the motion of the 
front wheels restrained if under any condition of turning of such wheels 
they will project beyond the widest part of either the towed or towing 
vehicle.
    (f) Vehicles to be towed in forward position. Unless the steering 
mechanism is adequately locked in a straight-forward position, all motor 
vehicles towed by means of a saddle-mount shall be towed with the front 
end mounted on the towing vehicle.
    (g) Means required for towing. No motor vehicles or combination of 
motor vehicles shall be towed in driveaway-towaway operations by means 
other than a tow-bar, ball-and-socket type coupling device, saddle-mount 
connections which meet the requirements of this section, or in the case 
of a semi-trailer equipped with an upper coupler assembly, a fifth-wheel 
meeting the requirements of Sec. 393.70.
    (h) Requirements for tow-bars. Tow-bars shall comply with the 
following requirements:

[[Page 415]]

    (1) Tow-bars, structural adequacy and mounting. Every tow-bar shall 
be structurally adequate and properly installed and maintained. To 
insure that it is structurally adequate, it must, at least, meet the 
requirements of the following table:

------------------------------------------------------------------------
                                    Longitudinal strength in tension and
                                               compression \2\
                                   -------------------------------------
                                                 New tow-
                                                   bars      Strength as
   Gross weight of towed vehicle                 acquired    a beam (in
           (pounds) \1\                          and used        any
                                     All tow-   by a motor    direction
                                       bars       carrier   concentrated
                                                   after       load at
                                                 Sept. 30,  center) 2, 3
                                                   1948
------------------------------------------------------------------------
                                                   Pounds

                                   -------------
Less than 5,000...................       3,000       6,500        3,000
5,000 and over....................  ..........  ..........  ............
Less than 10,000..................       6,000      (\1\ )       (\1\ )
10,000 and over...................  ..........  ..........  ............
Less than 15,000..................       9,000      (\1\ )       (\1\ )
------------------------------------------------------------------------
\1\ The required strength of tow-bars for towed vehicles of 15,000
  pounds and over gross weight and of new tow-bars acquired and used
  after Sept. 30, 1948, for towed vehicles of 5,000 pounds and over
  gross weight shall be computed by means of the following formulae:
  Longitudinal strength=gross weight of towed vehicle x 1.3. Strength as
  a beam=gross weight of towed vehicle x 0.6.
\2\ In testing, the whole unit shall be tested with all clamps, joints,
  and pins so mounted and fastened as to approximate conditions of
  actual operation.
\3\ This test shall be applicable only to tow-bars which are, in normal
  operation, subjected to a bending movement such as tow-bars for house
  trailers.

    (2) Tow-bars, jointed. The tow-bar shall be so constructed as to 
freely permit motion in both horizontal and vertical planes between the 
towed and towing vehicles. The means used to provide the motion shall be 
such as to prohibit the transmission of stresses under normal operation 
between the towed and towing vehicles, except along the longitudinal 
axis of the tongue or tongues.
    (3) Tow-bar fastenings. The means used to transmit the stresses to 
the chassis or frames of the towed and towing vehicles may be either 
temporary structures or bumpers or other integral parts of the vehicles: 
Provided, however, That the means used shall be so constructed, 
installed, and maintained that when tested as an assembly, failure in 
such members shall not occur when the weakest new tow-bar which is 
permissible under paragraph (h)(1) of this section is subjected to the 
tests given therein.
    (4) Means of adjusting length. On tow-bars, adjustable as to length, 
the means used to make such adjustment shall fit tightly and not result 
in any slackness or permit the tow-bar to bend. With the tow-bar 
supported rigidly at both ends and with a load of 50 pounds at the 
center, the sag, measured at the center, in any direction shall not 
exceed 0.25 inch under any condition of adjustment as to length.
    (5) Method of clamping. Adequate means shall be provided for 
securely fastening the tow-bar to the towed and towing vehicles.
    (6) Tow-bar connection to steering mechanism. The tow-bar shall be 
provided with suitable means of attachment to and actuation of the 
steering mechanism, if any, of the towed vehicle. The attachment shall 
provide for sufficient angularity of movement of the front wheels of the 
towed vehicle so that it may follow substantially in the path of the 
towing vehicle without cramping the tow-bar. The tow-bar shall be 
provided with suitable joints to permit such movement.
    (7) Tracking. The tow-bar shall be so designed, constructed, 
maintained, and mounted as to cause the towed vehicle to follow 
substantially in the path of the towing vehicle. Tow-bars of such design 
on in our condition as to permit the towed vehicle to deviate more than 
3 inches to either side of the path of a towing vehicle moving in a 
straight line as measured from the center of the towing vehicle are 
prohibited.
    (8) Passenger car-trailer type couplings. Trailer couplings used for 
driveaway-towaway operations of passenger car trailers shall conform to 
Society of Automotive Engineers Standard No. J684c, ``Trailer Couplings 
and Hitches--Automotive Type,'' July 1970. \1\
---------------------------------------------------------------------------

    \1\ See footnote 1 to Sec. 393.24(c).
---------------------------------------------------------------------------

    (9) Marking tow-bars. Every tow-bar acquired and used in driveaway-
towaway operations by a motor carrier shall be plainly marked with the 
following certification of the manufacturer thereof (or words of 
equivalent meaning):

    This tow-bar complies with the requirements of the Federal Motor 
Carrier Safety Administration for (maximum gross weight for which tow-
bar is manufactured) vehicles.
Allowable Maximum Gross Weight__________________________________________
Manufactured____________________________________________________________
 (month and year)
by______________________________________________________________________

[[Page 416]]

 (name of manufacturer)


Tow-bar certification manufactured before the effective date of this 
regulation must meet requirements in effect at the time of manufacture.
    (10) Safety devices in case of tow-bar failure or disconnection. (i) 
The towed vehicle shall be connected to the towing vehicle by a safety 
device to prevent the towed vehicle from breaking loose in the event the 
tow-bar fails or becomes disconnected. When safety chains or cables are 
used as the safety device for that vehicle, at least two safety chains 
or cables meeting the requirements of paragraph (h)(10)(ii) of this 
section shall be used. The tensile strength of the safety device and the 
means of attachment to the vehicles shall be at least equivalent to the 
corresponding longitudinal strength for tow-bars required in the table 
of paragraph (h)(1) of this section. If safety chains or cables are used 
as the safety device, the required strength shall be the combined 
strength of the combination of chains and cables.
    (ii) If chains or cables are used as the safety device, they shall 
be crossed and attached to the vehicles near the points of bumper 
attachments to the chassis of the vehicles. The length of chain used 
shall be no more than necessary to permit free turning of the vehicles. 
The chains shall be attached to the tow-bar at the point of crossing or 
as close to that point as is practicable.
    (iii) A safety device other than safety chains or cables must 
provide strength, security of attachment, and directional stability 
equal to, or greater than, that provided by safety chains or cables 
installed in accordance with paragraph (h)(10)(ii) of this section. A 
safety device other than safety chains or cables must be designed, 
constructed, and installed so that, if the tow-bar fails or becomes 
disconnected, the tow-bar will not drop to the ground.
    (i) [Reserved]
    (j) Requirements for upper-half of saddle-mounts. The upper-half of 
any saddle-mount shall comply with the following requirements:
    (1) Upper-half connection to towed vehicle. The upper-half shall be 
securely attached to the frame or axle of the towed vehicle by means of 
U-bolts or other means providing at least equivalent security.
    (2) U-bolts or other attachments. U-bolts used to attach the upper 
half to the towed vehicle shall be made of steel rod, free of defects, 
so shaped as to avoid at any point a radius of less than 1 inch: 
Provided, however, That a lesser radius may be utilized if the U-bolt is 
so fabricated as not to cause more than 5 percent reduction in cross-
sectional area at points of curvature, in which latter event the minimum 
radius shall be one-sixteenth inch. U-bolts shall have a diameter not 
less than required by the following table:

                      Diameter of U-Bolts in Inches
------------------------------------------------------------------------
                                         Double or triple saddle-mount
                                     -----------------------------------
 Weight in pounds of heaviest towed             Middle            Single
               vehicle                 Front      or      Rear   saddle-
                                       mount    front    mount    mount
                                                mount              \1\
------------------------------------------------------------------------
Up to 5,000.........................    0.625   0.5625    0.500    0.500
5,000 and over......................   0.6875    0.625   0.5625   0.5625
------------------------------------------------------------------------
\1\ The total weight of all the vehicles being towed shall govern. If
  other devices are used to accomplish the same purposes as U-bolts they
  shall have at least equivalent strength of U-bolts made of mild steel.
  Cast iron shall not be used for clamps or any other holding devices.

    (3) U-bolts and points of support, location. The distance between 
the most widely separated U-bolts shall not be less than 9 inches. The 
distance between the widely separated points where the upper-half 
supports the towed vehicle shall not be less than 9 inches, except that 
saddle-mounts employing ball and socket joints shall employ a device 
which clamps the axle of the towed vehicle throughout a length of not 
less than 5 inches.
    (4) Cradle-type upper-halves, specifications. Upper-halves of the 
cradle-type using vertical members to restrain the towed vehicle from 
relative movement in the direction of motion of the vehicles shall be 
substantially constructed and adequate for the purpose. Such cradle-
mounts shall be equipped with at least one bolt or equivalent means to 
provide against relative vertical movement between the upper-half and 
the towed vehicle. Bolts, if used, shall be at least one-half inch in 
diameter. Devices using equivalent means shall have at least equivalent 
strength. The means used to provide against relative vertical motion 
between the upper-half and the towed vehicle shall be such as not to 
permit a relative motion of over

[[Page 417]]

one-half inch. The distance between the most widely separated points of 
support between the upper-half and the towed vehicle shall be at least 9 
inches.
    (5) Lateral movement of towed vehicle. (i) Towed vehicles having a 
straight axle or an axle having a drop of less than 3 inches, unless the 
saddle-mount is constructed in accordance with paragraph (m)(2) of this 
section, shall be securely fastened by means of chains or cables to the 
upper-half so as to insure against relative lateral motion between the 
towed vehicle and the upper-half. The chains or cables shall be at least 
\3/16\-inch diameter and secured by bolts of at least equal diameter.
    (ii) Towed vehicles with an axle with a drop of 3 inches or more, or 
connected by a saddle-mount constructed in accordance with paragraph 
(m)(2) of this section, need not be restrained by chains or cables 
provided that the upper-half is so designed as to provide against such 
relative motion.
    (iii) Chains or cables shall not be required if the upper-half is so 
designed as positively to provide against lateral movement of the axle.
    (k) Requirements for lower half of saddle-mounts. The lower half of 
any saddle-mount shall comply with the following requirements:
    (1) U-bolts or other attachments. U-bolts used to attach the lower 
half to the towing vehicle shall be made of steel rod, free of defects, 
so shaped as to avoid at any point a radius of less than 1 inch: 
Provided, however, That a lesser radius may be utilized if the U-bolt is 
so fabricated as not to cause more than 5 percent reduction in cross-
sectional area at points of curvature, in which latter event the minimum 
radius shall be one-sixteenth inch. U-bolts shall have a total cross-
sectional area not less than as required by the following table:

         Total Cross-Sectional Area of U-Bolts in Square Inches
------------------------------------------------------------------------
                                         Double or triple saddle-mount
                                     -----------------------------------
 Weight in pounds of heaviest towed             Middle            Single
               vehicle                 Front      or      Rear   saddle-
                                       mount    front    mount    mount
                                                mount              \1\
------------------------------------------------------------------------
Up to 5,000.........................      1.2      1.0      0.8      0.8
5,000 and over......................      1.4      1.2      1.0      1.0
------------------------------------------------------------------------
\1\ The total weight of all the vehicles being towed shall govern. If
  other devices are used to accomplish the same purposes as U-bolts they
  shall have at least equivalent strength of U-bolts made of mild steel.
  Cast iron shall not be used for clamps or any other holding devices.

    (2) Shifting. Adequate provision shall be made by design and 
installation to provide against relative movement between the lower-half 
and the towing vehicle especially during periods of rapid acceleration 
and deceleration. To insure against shifting, designs of the tripod type 
shall be equipped with adequate and securely fastened hold-back chains 
or similar devices.
    (3) Swaying. (i) Adequate provision shall be made by design and 
installation to provide against swaying or lateral movement of the towed 
vehicle relative to the towing vehicle. To insure against swaying, 
lower-halves designed with cross-members attached to but separable from 
vertical members shall have such cross-members fastened to the vertical 
members by at least two bolts on each side. Such bolts shall be of at 
least equivalent cross-sectional area as those required for U-bolts for 
the corresponding saddle-mount as given in the table in paragraph (k)(1) 
of this section. The minimum distance between the most widely separated 
points of support of the cross-member by the vertical member shall be 
three inches as measured in a direction parallel to the longitudinal 
axis of the towing vehicle.
    (ii) The lower-half shall have a bearing surface on the frame of the 
towing vehicle of such dimensions that the pressure exerted by the 
lower-half upon the frame of the towing vehicle shall not exceed 200 
pounds per square inch under any conditions of static loading. Hardwood 
blocks or blocks of other suitable material, such as hard rubber, 
aluminum or brakelining, if used between the lower half and the frame of 
the towing vehicle shall be at least \1/2\ inch thick, 3 inches wide, 
and a combined length of 6 inches.

[[Page 418]]

    (iii) Under no condition shall the highest point of support of the 
towed vehicle by the upper-half be more than 24 inches, measured 
vertically, above the top of the frame of the towing vehicle, measured 
at the point where the lower-half rests on the towing vehicle.
    (4) Wood blocks. (i) Hardwood blocks of good quality may be used to 
build up the height of the front end of the towed vehicle, provided that 
the total height of such wood blocks shall not exceed 8 inches and not 
over two separate pieces are placed upon each other to obtain such 
height; however, hardwood blocks, not over 4 in number, to a total 
height not to exceed 14 inches, may be used if the total cross-sectional 
area of the U-bolts used to attach the lower-half of the towing vehicle 
is at least 50 percent greater than that required by the table contained 
in paragraph (k)(1) of this section, or, if other devices are used in 
lieu of U-bolts, they shall provide for as great a resistance to bending 
as is provided by the larger U-bolts above prescribed.
    (ii) Hardwood blocks must be at least 4 inches in width and the 
surfaces between blocks or block and lower-half or block and upper-half 
shall be planed and so installed and maintained as to minimize any 
tendency of the towed vehicle to sway or rock.
    (5) Cross-member, general requirements. The cross-member, which is 
that part of the lower-half used to distribute the weight of the towed 
vehicle equally to each member of the frame of the towing vehicle, if 
used, shall be structurally adequate and properly installed and 
maintained adequately to perform this function.
    (6) Cross-member, use of wood. No materials, other than suitable 
metals, shall be used as the cross-member, and wood may not be used 
structurally in any manner that will result in its being subject to 
tensile stresses. Wood may be used in cross-members if supported 
throughout its length by suitable metal cross-members.
    (7) Lower half strength. The lower half shall be capable of 
supporting the loads given in the following table. For the purpose of 
test, the saddle-mount shall be mounted as normally operated and the 
load applied through the upper half:

                       Minimum Test Load in Pounds
------------------------------------------------------------------------
                                         Double or triple saddle-mount
                                     -----------------------------------
 Weight in pounds of heaviest towed             Middle            Single
               vehicle                 Front      or      Rear   saddle-
                                       mount    front    mount    mount
                                                mount              \1\
------------------------------------------------------------------------
Up to 5,000.........................   15,000   10,000    5,000    5,000
5,000 and over......................   30,000   20,000   10,000   10,000
------------------------------------------------------------------------
\1\ The total weight of all the vehicles being towed shall govern.

    (l) Requirements for kingpins of saddle-mounts. The kingpin of any 
saddle-mount shall comply with the following requirements:
    (1) Kingpin size. (i) Kingpins shall be constructed of steel 
suitable for the purpose, free of defects, and having a diameter not 
less than required by the following table:

                                       Diameter of Solid Kingpin in Inches
----------------------------------------------------------------------------------------------------------------
                                                            Double or triple saddle-mount
                                   -----------------------------------------------------------------------------
                                        Front mount       Middle or front       Rear mount       Single saddle-
Weight in pounds of heaviest towed --------------------        mount       --------------------     mount \1\
              vehicle                                  --------------------                    -----------------
                                      Mild   H.T.S.\2\    Mild                Mild   H.T.S.\2\    Mild
                                     steel               steel   H.T.S.\2\   steel               steel    H.T.S.
----------------------------------------------------------------------------------------------------------------
Up to 5,000.......................    1.125     1.000     1.000     0.875     0.875     0.750     0.875    0.750
5,000 and over....................    1.500     1.125     1.250     1.000     1.000     0.875     1.000    0.875
----------------------------------------------------------------------------------------------------------------
\1\ The total weight of all the vehicles being towed shall govern.
\2\ High-tensile steel is steel having a minimum ultimate strength of 65,000 pounds per square inch.

    (ii) If a ball and socket joint is used in place of a kingpin, the 
diameter of the neck of the ball shall be at least equal to the diameter 
of the corresponding solid kingpin given in the above table. If hollow 
kingpins are used, the metallic cross-sectional area shall be at least 
equal to the cross-sectional area of the corresponding solid kingpin.
    (2) Kingpin fit. If a kingpin bushing is not used, the king-pin 
shall fit snugly

[[Page 419]]

into the upper and lower-halves but shall not bind. Those portions of 
the upper or lower-halves in moving contact with the kingpin shall be 
smoothly machined with no rough or sharp edges. The bearing surface thus 
provided shall not be less in depth than the radius of the kingpin.
    (3) Kingpin bushing on saddle-mounts. The kingpin of all new saddle-
mounts acquired and used shall be snugly enclosed in a bushing at least 
along such length of the kingpin as may be in moving contact with either 
the upper or lower-halves. The bearing surface thus provided shall not 
be less in depth than the radius of the kingpin.
    (4) Kingpin to restrain vertical motion. The kingpin shall be so 
designed and installed as to restrain the upper-half from moving in a 
vertical direction relative to the lower-half.
    (m) Additional requirements for saddle-mounts. Saddle-mounts shall 
comply with the following requirements:
    (1) Bearing surface between upper and lower-halves. The upper and 
lower-halves shall be so constructed and connected that the bearing 
surface between the two halves shall not be less than 16 square inches 
under any conditions of angularity between the towing and towed 
vehicles: Provided, however, That saddle-mounts using a ball and socket 
joint shall have a ball of such dimension that the static bearing load 
shall not exceed 800 pounds per square inch, based on the projected 
cross-sectional area of the ball: And further provided, That saddle-
mounts having the upper-half supported by ball, taper, or roller-
bearings shall not have such bearings loaded beyond the limits 
prescribed for such bearings by the manufacturer thereof. The upper-half 
shall rest evenly and smoothly upon the lower-half and the contact 
surfaces shall be lubricated and maintained so that there shall be a 
minimum of frictional resistance between the parts.
    (2) Saddle-mounts, angularity. All saddle-mounts acquired and used 
shall provide for angularity between the towing and towed vehicles due 
to vertical curvatures of the highway. Such means shall not depend upon 
either the looseness or deformation of the parts of either the saddle-
mount or the vehicles to provide for such angularity.
    (3) Tracking. The saddle-mount shall be so designed, constructed, 
maintained, and installed that the towed vehicle or vehicles will follow 
substantially in the path of the towing vehicle without swerving. Towed 
vehicles shall not deviate more than 3 inches to either side of the path 
of the towing vehicle when moving in a straight line.
    (4) Prevention of frame bending. Where necessary, provision shall be 
made to prevent the bending of the frame of the towing vehicle by 
insertion of suitable blocks inside the frame channel to prevent 
kinking. The saddle-mount shall not be so located as to cause 
deformation of the frame by reason of cantilever action.
    (5) Extension of frame. No saddle-mount shall be located at a point 
to the rear of the frame of a towing vehicle.
    (6) Nuts, secured. All nuts used on bolts, U-bolts, king-pins, or in 
any other part of the saddle-mount shall be secured against accidental 
disconnection by means of cotter-keys, lock-washers, double nuts, safety 
nuts, or equivalent means. Parts shall be so designed and installed that 
nuts shall be fully engaged.
    (7) Inspection of all parts. The saddle-mount shall be so designed 
that it may be disassembled and each separate part inspected for worn, 
bent, cracked, broken, or missing parts.
    (8) Saddle-mounts, marking. Every new saddle-mount acquired and used 
in driveaway-towaway operations by a motor carrier shall have the upper-
half and the lower-half separately marked with the following 
certification of the manufacturer thereof (or words of equivalent 
meaning).

    This saddle-mount complies with the requirements of the Federal 
Motor Carrier Safety Administration for vehicles up to 5,000 pounds (or 
over 5,000 pounds):

Manufactured____________________________________________________________
                                                        (Month and year)
by______________________________________________________________________
                                                  (Name of manufacturer)

    (n) Requirements for devices used to connect motor vehicles or parts 
of motor vehicles together to form one vehicle--(1) Front axle 
attachment. The front axle of

[[Page 420]]

one motor vehicle intended to be coupled with another vehicle as defined 
in paragraph (g)(2)(ii) of this section shall be attached with U-bolts 
meeting the requirements of paragraph (j)(2) of this section.
    (2) Rear axle attachment. The rear axle of one vehicle shall be 
coupled to the frame of the other vehicle by means of a connecting 
device which when in place forms a rectangle. The device shall be 
composed of two pieces, top and bottom. The device shall be made of 4-
inch by \1/2\-inch steel bar bent to shape and shall have the corners 
reinforced with a plate at least 3 inches by \1/2\ inch by 8 inches 
long. The device shall be bolted together with \3/4\-inch bolts and at 
least three shall be used on each side. Wood may be used as spacers to 
keep the frames apart and it shall be at least 4 inches square.

(Sec. 12, 80 Stat. 931; 49 U.S.C. 1651 note; section 6 of the Department 
of Transportation Act, 49 U.S.C. 1655, and the delegations of authority 
at 49 CFR 1.48 and 389.4)

[33 FR 19735, Dec. 25, 1968, as amended at 35 FR 10907, July 7, 1970; 37 
FR 21440, Oct. 11, 1972; 53 FR 49400, Dec. 7, 1988; 70 FR 48054, Aug. 
15, 2005]

              Subpart G_Miscellaneous Parts and Accessories

Sec. 393.75  Tires.

    (a) No motor vehicle shall be operated on any tire that (1) has body 
ply or belt material exposed through the tread or sidewall, (2) has any 
tread or sidewall separation, (3) is flat or has an audible leak, or (4) 
has a cut to the extent that the ply or belt material is exposed.
    (b) Any tire on the front wheels of a bus, truck, or truck tractor 
shall have a tread groove pattern depth of at least \4/32\ of an inch 
when measured at any point on a major tread groove. The measurements 
shall not be made where tie bars, humps, or fillets are located.
    (c) Except as provided in paragraph (b) of this section, tires shall 
have a tread groove pattern depth of at least \2/32\ of an inch when 
measured in a major tread groove. The measurement shall not be made 
where tie bars, humps or fillets are located.
    (d) No bus shall be operated with regrooved, recapped or retreaded 
tires on the front wheels.
    (e) A regrooved tire with a load-carrying capacity equal to or 
greater than 2,232 kg (4,920 pounds) shall not be used on the front 
wheels of any truck or truck tractor.
    (f) Tire loading restrictions (except on manufactured homes). No 
motor vehicle (except manufactured homes, which are governed by 
paragraph (g) of this section) shall be operated with tires that carry a 
weight greater than that marked on the sidewall of the tire or, in the 
absence of such a marking, a weight greater than that specified for the 
tires in any of the publications of any of the organizations listed in 
Federal Motor Vehicle Safety Standard No. 119 (49 CFR 571.119, S5.1(b)) 
unless:
    (1) The vehicle is being operated under the terms of a special 
permit issued by the State; and
    (2) The vehicle is being operated at a reduced speed to compensate 
for the tire loading in excess of the manufacturer's rated capacity for 
the tire. In no case shall the speed exceed 80 km/hr (50 mph).
    (g)(1) Tire loading restrictions for manufactured homes built before 
January 1, 2002. Manufactured homes that are labeled pursuant to 24 CFR 
3282.362(c)(2)(i) before January 1, 2002, must not be transported on 
tires that are loaded more than 18 percent over the load rating marked 
on the sidewall of the tire or, in the absence of such a marking, more 
than 18 percent over the load rating specified in any of the 
publications of any of the organizations listed in FMVSS No. 119 (49 CFR 
571.119, S5.1(b)). Manufactured homes labeled before January 1, 2002, 
transported on tires overloaded by 9 percent or more must not be 
operated at speeds exceeding 80 km/hr (50 mph).
    (2) Tire loading restrictions for manufactured homes built on or 
after January 1, 2002. Manufactured homes that are labeled pursuant to 
24 CFR 3282.362(c)(2)(i) on or after January 1, 2002, must not be 
transported on tires loaded beyond the load rating marked on the 
sidewall of the tire or, in the absence of such a marking, the load 
rating specified in any of the publications

[[Page 421]]

of any of the organizations listed in FMVSS No. 119 (49 CFR 571.119, 
S5.1(b)).
    (h) Tire inflation pressure. (1) No motor vehicle shall be operated 
on a tire which has a cold inflation pressure less than that specified 
for the load being carried.
    (2) If the inflation pressure of the tire has been increased by heat 
because of the recent operation of the vehicle, the cold inflation 
pressure shall be estimated by subtracting the inflation buildup factor 
shown in Table 1 from the measured inflation pressure.

       Table 1--Inflation Pressure Measurement Correction for Heat
------------------------------------------------------------------------
                                    Minimum inflation pressure buildup
                                 ---------------------------------------
Average speed of vehicle  in the   Tires with 1,814
          previous hour             kg (4,000 lbs.)     Tires with over
                                     maximum load       1,814 kg (4,000
                                    rating or less     lbs.) load rating
------------------------------------------------------------------------
66-88.5 km/hr (41-55 mph).......  34.5 kPa (5 psi)..  103.4 kPa (15
                                                       psi).
------------------------------------------------------------------------


[34 FR 9344, June 13, 1969, as amended at 40 FR 44557, Sept. 29, 1975; 
41 FR 36657, Aug. 31, 1976; 44 FR 25455, May 1, 1979; 44 FR 47938, Aug. 
16, 1979; 53 FR 18057, May 19, 1988; 53 FR 49401, Dec. 7, 1988; 63 FR 
8339, Feb. 18, 1998; 65 FR 70220, Nov. 21, 2000; 66 FR 67694, Dec. 31, 
2001; 70 FR 48054, Aug. 15, 2005]

Sec. 393.76  Sleeper berths.

    (a) Dimensions--(1) Size. A sleeper berth must be at least the 
following size:

------------------------------------------------------------------------
                                                                Height
                                       Length        Width     measured
                                     measured on   measured      from
                                     centerline       on        highest
   Date of installation on motor         of       centerline   point of
              vehicle               longitudinal      of        top of
                                        axis      transverse   mattress
                                      (inches)       axis      (inches)
                                                   (inches)       \1\
------------------------------------------------------------------------
Before January 1, 1953............           72           18          18
After December 31, 1952, and                 75           21          21
 before October 1, 1975...........
After September 30, 1975..........           75           24          24
------------------------------------------------------------------------
\1\ In the case of a sleeper berth which utilizes an adjustable
  mechanical suspension system, the required clearance can be measured
  when the suspension system is adjusted to the height to which it would
  settle when occupied by a driver.

    (2) Shape. A sleeper berth installed on a motor vehicle on or after 
January 1, 1953 must be of generally rectangular shape, except that the 
horizontal corners and the roof corners may be rounded to radii not 
exceeding 10\1/2\ inches.
    (3) Access. A sleeper berth must be constructed so that an 
occupant's ready entrance to, and exit from, the sleeper berth is not 
unduly hindered.
    (b) Location. (1) A sleeper berth must not be installed in or on a 
semitrailer or a full trailer other than a house trailer.
    (2) A sleeper berth located within the cargo space of a motor 
vehicle must be securely compartmentalized from the remainder of the 
cargo space. A sleeper berth installed on or after January 1, 1953 must 
be located in the cab or immediately adjacent to the cab and must be 
securely fixed with relation to the cab.
    (c) Exit from the berth. (1) Except as provided in paragraph (c)(2) 
of this section, there must be a direct and ready means of exit from a 
sleeper berth into the driver's seat or compartment. If the sleeper 
berth was installed on or after January 1, 1963, the exit must be a 
doorway or opening at least 18 inches high and 36 inches wide. If the 
sleeper berth was installed before January 1, 1963, the exit must have 
sufficient area to contain an ellipse having a major axis of 24 inches 
and a minor axis of 16 inches.
    (2) A sleeper berth installed before January 1, 1953 must either:
    (i) Conform to the requirements of paragraph (c)(1) of this section; 
or
    (ii) Have at least two exits, each of which is at least 18 inches 
high and 21 inches wide, located at opposite ends of the vehicle and 
useable by the occupant without the assistance of any other person.
    (d) Communication with the driver. A sleeper berth which is not 
located within the driver's compartment and has no direct entrance into 
the driver's compartment must be equipped with a means of communication 
between the occupant and the driver. The means of communication may 
consist of a telephone, speaker tube, buzzer, pull cord, or other 
mechanical or electrical device.
    (e) Equipment. A sleeper berth must be properly equipped for 
sleeping. Its equipment must include:
    (1) Adequate bedclothing and blankets; and
    (2) Either:
    (i) Springs and a mattress; or

[[Page 422]]

    (ii) An innerspring mattress; or
    (iii) A cellular rubber or flexible foam mattress at least four 
inches thick; or
    (iv) A mattress filled with a fluid and of sufficient thickness when 
filled to prevent ``bottoming-out'' when occupied while the vehicle is 
in motion.
    (f) Ventilation. A sleeper berth must have louvers or other means of 
providing adequate ventilation. A sleeper berth must be reasonably tight 
against dust and rain.
    (g) Protection against exhaust and fuel leaks and exhaust heat. A 
sleeper berth must be located so that leaks in the vehicle's exhaust 
system or fuel system do not permit fuel, fuel system gases, or exhaust 
gases to enter the sleeper berth. A sleeper berth must be located so 
that it will not be overheated or damaged by reason of its proximity to 
the vehicle's exhaust system.
    (h) Occupant restraint. A motor vehicle manufactured on or after 
July 1, 1971, and equipped with a sleeper berth must be equipped with a 
means of preventing ejection of the occupant of the sleeper berth during 
deceleration of the vehicle. The restraint system must be designed, 
installed, and maintained to withstand a minimum total force of 6,000 
pounds applied toward the front of the vehicle and parallel to the 
longitudinal axis of the vehicle.

[39 FR 14711, Apr. 26, 1974; 39 FR 17233, May 14, 1974, as amended at 53 
FR 49401, Dec. 7, 1988]

Sec. 393.77  Heaters.

    On every motor vehicle, every heater shall comply with the following 
requirements:
    (a) Prohibited types of heaters. The installation or use of the 
following types of heaters is prohibited:
    (1) Exhaust heaters. Any type of exhaust heater in which the engine 
exhaust gases are conducted into or through any space occupied by 
persons or any heater which conducts engine compartment air into any 
such space.
    (2) Unenclosed flame heaters. Any type of heater employing a flame 
which is not fully enclosed, except that such heaters are not prohibited 
when used for heating the cargo of tank motor vehicles.
    (3) Heaters permitting fuel leakage. Any type of heater from the 
burner of which there could be spillage or leakage of fuel upon the 
tilting or overturning of the vehicle in which it is mounted.
    (4) Heaters permitting air contamination. Any heater taking air, 
heated or to be heated, from the engine compartment or from direct 
contact with any portion of the exhaust system; or any heater taking air 
in ducts from the outside atmosphere to be conveyed through the engine 
compartment, unless said ducts are so constructed and installed as to 
prevent contamination of the air so conveyed by exhaust or engine 
compartment gases.
    (5) Solid fuel heaters except wood charcoal. Any stove or other 
heater employing solid fuel except wood charcoal.
    (6) Portable heaters. Portable heaters shall not be used in any 
space occupied by persons except the cargo space of motor vehicles which 
are being loaded or unloaded.
    (b) Heater specifications. All heaters shall comply with the 
following specifications:
    (1) Heating elements, protection. Every heater shall be so located 
or protected as to prevent contact therewith by occupants, unless the 
surface temperature of the protecting grilles or of any exposed portions 
of the heaters, inclusive of exhaust stacks, pipes, or conduits shall be 
lower than would cause contact burns. Adequate protection shall be 
afforded against igniting parts of the vehicle or burning occupants by 
direct radiation. Wood charcoal heaters shall be enclosed within a metal 
barrel, drum, or similar protective enclosure which enclosure shall be 
provided with a securely fastened cover.
    (2) Moving parts, guards. Effective guards shall be provided for the 
protection of passengers or occupants against injury by fans, belts, or 
any other moving parts.
    (3) Heaters, secured. Every heater and every heater enclosure shall 
be securely fastened to the vehicle in a substantial manner so as to 
provide against relative motion within the vehicle during normal usage 
or in the event the vehicle overturns. Every heater shall be so 
designed, constructed, and mounted as to minimize the likelihood of 
disassembly of any of

[[Page 423]]

its parts, including exhaust stacks, pipes, or conduits, upon overturn 
of the vehicle in or on which it is mounted. Wood charcoal heaters shall 
be secured against relative motion within the enclosure required by 
paragraph (c)(1) of this section, and the enclosure shall be securely 
fastened to the motor vehicle.
    (4) Relative motion between fuel tank and heater. When either in 
normal operation or in the event of overturn, there is or is likely to 
be relative motion between the fuel tank for a heater and the heater, or 
between either of such units and the fuel lines between them, a suitable 
means shall be provided at the point of greatest relative motion so as 
to allow this motion without causing failure of the fuel lines.
    (5) Operating controls to be protected. On every bus designed to 
transport more than 15 passengers, including the driver, means shall be 
provided to prevent unauthorized persons from tampering with the 
operating controls. Such means may include remote control by the driver; 
installation of controls at inaccessible places; control of adjustments 
by key or keys; enclosure of controls in a locked space, locking of 
controls, or other means of accomplishing this purpose.
    (6) Heater hoses. Hoses for all hot water and steam heater systems 
shall be specifically designed and constructed for that purpose.
    (7) Electrical apparatus. Every heater employing any electrical 
apparatus shall be equipped with electrical conductors, switches, 
connectors, and other electrical parts of ample current-carrying 
capacity to provide against overheating; any electric motor employed in 
any heater shall be of adequate size and so located that it will not be 
overheated; electrical circuits shall be provided with fuses and/or 
circuit breakers to provide against electrical overloading; and all 
electrical conductors employed in or leading to any heater shall be 
secured against dangling, chafing, and rubbing and shall have suitable 
protection against any other condition likely to produce short or open 
circuits.

    Note: Electrical parts certified as proper for use by Underwriters' 
Laboratories, Inc., shall be deemed to comply with the foregoing 
requirements.

    (8) Storage battery caps. If a separate storage battery is located 
within the personnel or cargo space, such battery shall be securely 
mounted and equipped with nonspill filler caps.
    (9) Combustion heater exhaust construction. Every heater employing 
the combustion of oil, gas, liquefied petroleum gas, or any other 
combustible material shall be provided with substantial means of 
conducting the products of combustion to the outside of the vehicle: 
Provided, however, That this requirement shall not apply to heaters used 
solely to heat the cargo space of motor vehicles where such motor 
vehicles or heaters are equipped with means specifically designed and 
maintained so that the carbon monoxide concentration will never exceed 
0.2 percent in the cargo space. The exhaust pipe, stack, or conduit if 
required shall be sufficiently substantial and so secured as to provide 
reasonable assurance against leakage or discharge of products of 
combustion within the vehicle and, if necessary, shall be so insulated 
as to make unlikely the burning or charring of parts of the vehicle by 
radiation or by direct contact. The place of discharge of the products 
of combustion to the atmosphere and the means of discharge of such 
products shall be such as to minimize the likelihood of their reentry 
into the vehicle under all operating conditions.
    (10) Combustion chamber construction. The design and construction of 
any combustion-type heater except cargo space heaters permitted by the 
proviso of paragraph (c)(9) of this section and unenclosed flame heaters 
used for heating cargo of tank motor vehicles shall be such as to 
provide against the leakage of products of combustion into air to be 
heated and circulated. The material employed in combustion chambers 
shall be such as to provide against leakage because of corrosion, 
oxidation, or other deterioration. Joints between combustion chambers 
and the air chambers with which they are in thermal and mechanical 
contact shall be so designed and constructed as to prevent leakage 
between the chambers and the materials employed in such joints shall 
have melting points substantially higher than the maximum

[[Page 424]]

temperatures likely to be attained at the points of jointure.
    (11) Heater fuel tank location. Every bus designed to transport more 
than 15 passengers, including the driver, with heaters of the combustion 
type shall have fuel tanks therefor located outside of and lower than 
the passenger space. When necessary, suitable protection shall be 
afforded by shielding or other means against the puncturing of any such 
tank or its connections by flying stones or other objects.
    (12) Heater, automatic fuel control. Gravity or siphon feed shall 
not be permitted for heaters using liquid fuels. Heaters using liquid 
fuels shall be equipped with automatic means for shutting off the fuel 
or for reducing such flow of fuel to the smallest practicable magnitude, 
in the event of overturn of the vehicle. Heaters using liquefied 
petroleum gas as fuel shall have the fuel line equipped with automatic 
means at the source of supply for shutting off the fuel in the event of 
separation, breakage, or disconnection of any of the fuel lines between 
the supply source and the heater.
    (13) ``Tell-tale'' indicators. Heaters subject to paragraph (c)(14) 
of this section and not provided with automatic controls shall be 
provided with ``tell-tale'' means to indicate to the driver that the 
heater is properly functioning. This requirement shall not apply to 
heaters used solely for the cargo space in semitrailers or full 
trailers.
    (14) Shut-off control. Automatic means, or manual means if the 
control is readily accessible to the driver without moving from the 
driver's seat, shall be provided to shut off the fuel and electrical 
supply in case of failure of the heater to function for any reason, or 
in case the heater should function improperly or overheat. This 
requirement shall not apply to wood charcoal heaters or to heaters used 
solely to heat the contents of cargo tank motor vehicles, but wood 
charcoal heaters must be provided with a controlled method of regulating 
the flow of combustion air.
    (15) Certification required. Every combustion-type heater, except 
wood charcoal heaters, the date of manufacture of which is subsequent to 
December 31, 1952, and every wood charcoal heater, the date of 
manufacture of which is subsequent to September 1, 1953, shall be marked 
plainly to indicate the type of service for which such heater is 
designed and with a certification by the manufacturer that the heater 
meets the applicable requirements for such use. For example, ``Meets 
I.C.C. Bus Heater Requirements,'' Meets I.C.C. Flue-Vented Cargo Space 
Heater Requirements,'' and after December 31, 1967, such certification 
shall read ``Meets FMCSA Bus Heater Requirements,'' ``Meets FMCSA Flue-
Vented Cargo Space Heater Requirements,'' etc.
    (i) Exception. The certification for a catalytic heater which is 
used in transporting flammable liquid or gas shall be as prescribed 
under Sec. 177.834(1) of this title.

[33 FR 19735, Dec. 25, 1968, as amended at 40 FR 51198, Nov. 4, 1975; 53 
FR 49401, Dec. 7, 1988]

Sec. 393.78  Windshield wiping and washing systems.

    (a) Vehicles manufactured on or after December 25, 1968. Each bus, 
truck, and truck-tractor manufactured on or after December 25, 1968, 
must have a windshield wiping system that meets the requirements of 
FMVSS No. 104 (S4.1) in effect on the date of manufacture. Each of these 
vehicles must have a windshield washing system that meets the 
requirements of FMVSS No. 104 (S4.2.2) in effect on the date of 
manufacture.
    (b) Vehicles manufactured between June 30, 1953, and December 24, 
1968. Each truck, truck-tractor, and bus manufactured between June 30, 
1953, and December 24, 1968, shall be equipped with a power-driven 
windshield wiping system with at least two wiper blades, one on each 
side of the centerline of the windshield. Motor vehicles which depend 
upon vacuum to operate the windshield wipers, shall have the wiper 
system constructed and maintained such that the performance of the 
wipers will not be adversely affected by a change in the intake manifold 
pressure.
    (c) Driveaway-towaway operations. Windshield wiping and washing 
systems need not be in working condition while a commercial motor 
vehicle is

[[Page 425]]

being towed in a driveaway-towaway operation.

[70 FR 48054, Aug. 15, 2005]

Sec. 393.79  Windshield defrosting and defogging systems.

    (a) Vehicles manufactured on or after December 25, 1968. Each bus, 
truck, and truck-tractor manufactured on or after December 25, 1968, 
must have a windshield defrosting and defogging system that meets the 
requirements of FMVSS No. 103 in effect on the date of manufacture.
    (b) Vehicles manufactured before December 25, 1968. Each bus, truck, 
and truck-tractor shall be equipped with a means for preventing the 
accumulation of ice, snow, frost, or condensation that could obstruct 
the driver's view through the windshield while the vehicle is being 
driven.

[70 FR 48054, Aug. 15, 2005]

Sec. 393.80  Rear-vision mirrors.

    (a) Every bus, truck, and truck tractor shall be equipped with two 
rear-vision mirrors, one at each side, firmly attached to the outside of 
the motor vehicle, and so located as to reflect to the driver a view of 
the highway to the rear, along both sides of the vehicle. All such 
regulated rear-vision mirrors and their replacements shall meet, as a 
minimum, the requirements of FMVSS No. 111 (49 CFR 571.111) in force at 
the time the vehicle was manufactured.
    (b) Exceptions. (1) Mirrors installed on a vehicle manufactured 
prior to January 1, 1981, may be continued in service, provided that if 
the mirrors are replaced they shall be replaced with mirrors meeting, as 
a minimum, the requirements of FMVSS No. 111 (49 CFR 571.111) in force 
at the time the vehicle was manufactured.
    (2) Only one outside mirror shall be required, which shall be on the 
driver's side, on trucks which are so constructed that the driver has a 
view to the rear by means of an interior mirror.
    (3) In driveway-towaway operations, the driven vehicle shall have at 
least one mirror furnishing a clear view to the rear.

[48 FR 57139, Dec. 28, 1983]

Sec. 393.81  Horn.

    Every bus, truck, truck-tractor, and every driven motor vehicle in 
drive away-towaway operations shall be equipped with a horn and 
actuating elements which shall be in such condition as to give an 
adequate and reliable warning signal.

Sec. 393.82  Speedometer.

    Each bus, truck, and truck-tractor must be equipped with a 
speedometer indicating vehicle speed in miles per hour and/or kilometers 
per hour. The speedometer must be accurate to within plus or minus 8 km/
hr (5 mph) at a speed of 80 km/hr (50 mph).

[70 FR 48054, Aug. 15, 2005]

Sec. 393.83  Exhaust systems.

    (a) Every motor vehicle having a device (other than as part of its 
cargo) capable of expelling harmful combustion fumes shall have a system 
to direct the discharge of such fumes. No part shall be located where 
its location would likely result in burning, charring, or damaging the 
electrical wiring, the fuel supply, or any combustible part of the motor 
vehicle.
    (b) No exhaust system shall discharge to the atmosphere at a 
location immediately below the fuel tank or the fuel tank filler pipe.
    (c) The exhaust system of a bus powered by a gasoline engine shall 
discharge to the atmosphere at or within 6 inches forward of the 
rearmost part of the bus.
    (d) The exhaust system of a bus using fuels other than gasoline 
shall discharge to the atmosphere either:
    (1) At or within 15 inches forward of the rearmost part of the 
vehicle; or
    (2) To the rear of all doors or windows designed to be open, except 
windows designed to be opened solely as emergency exits.
    (e) The exhaust system of every truck and truck tractor shall 
discharge to the atmosphere at a location to the rear of the cab or, if 
the exhaust projects above the cab, at a location near the rear of the 
cab.
    (f) No part of the exhaust system shall be temporarily repaired with 
wrap or patches.

[[Page 426]]

    (g) No part of the exhaust system shall leak or discharge at a point 
forward of or directly below the driver/sleeper compartment. The exhaust 
outlet may discharge above the cab/sleeper roofline.
    (h) The exhaust system must be securely fastened to the vehicle.
    (i) Exhaust systems may use hangers which permit required movement 
due to expansion and contraction caused by heat of the exhaust and 
relative motion between engine and chassis of a vehicle.

[53 FR 49401, Dec. 7, 1988]

Sec. 393.84  Floors.

    The flooring in all motor vehicles shall be substantially 
constructed, free of unnecessary holes and openings, and shall be 
maintained so as to minimize the entrance of fumes, exhaust gases, or 
fire. Floors shall not be permeated with oil or other substances likely 
to cause injury to persons using the floor as a traction surface.

[53 FR 49401, Dec. 7, 1988]

Sec. 393.85  [Reserved]

Sec. 393.86  Rear impact guards and rear end protection.

    (a)(1) General requirements for trailers and semitrailers 
manufactured on or after January 26, 1998. Each trailer and semitrailer 
with a gross vehicle weight rating of 4,536 kg (10,000 pounds) or more, 
and manufactured on or after January 26, 1998, must be equipped with a 
rear impact guard that meets the requirements of Federal Motor Vehicle 
Safety Standard No. 223 (49 CFR 571.223) in effect at the time the 
vehicle was manufactured. When the rear impact guard is installed on the 
trailer or semitrailer, the vehicle must, at a minimum, meet the 
requirements of FMVSS No. 224 (49 CFR 571.224) in effect at the time the 
vehicle was manufactured. The requirements of paragraph (a) of this 
section do not apply to pole trailers (as defined in Sec. 390.5 of this 
chapter); pulpwood trailers, low chassis vehicles, special purpose 
vehicles, wheels back vehicles (as defined in Sec. 393.5); and trailers 
towed in driveaway-towaway operations (as defined in Sec. 390.5).
    (2) Impact guard width. The outermost surfaces of the horizontal 
member of the guard must extend to within 100 mm (4 inches) of the side 
extremities of the vehicle. The outermost surface of the horizontal 
member shall not extend beyond the side extremity of the vehicle.
    (3) Guard height. The vertical distance between the bottom edge of 
the horizontal member of the guard and the ground shall not exceed 560 
mm (22 inches) at any point across the full width of the member. Guards 
with rounded corners may curve upward within 255 mm (10 inches) of the 
longitudinal vertical planes that are tangent to the side extremities of 
the vehicle.
    (4) Guard rear surface. At any height 560 mm (22 inches) or more 
above the ground, the rearmost surface of the horizontal member of the 
guard must be within 305 mm (12 inches) of the rear extremity of the 
vehicle. This paragraph shall not be construed to prohibit the rear 
surface of the guard from extending beyond the rear extremity of the 
vehicle. Guards with rounded corners may curve forward within 255 mm (10 
inches) of the side extremity.
    (5) Cross-sectional vertical height. The horizontal member of each 
guard must have a cross sectional vertical height of at least 100 mm 
(3.94 inches) at any point across the guard width.
    (6) Certification and labeling requirements for rear impact 
protection guards. Each rear impact guard used to satisfy the 
requirements of paragraph (a)(1) of this section must be permanently 
marked or labeled as required by FMVSS No. 223 (49 CFR 571.223, S5.3). 
The label must be on the forward-facing surface of the horizontal member 
of the guard, 305 mm (12 inches) inboard of the right end of the guard. 
The certification label must contain the following information:
    (i) The impact guard manufacturer's name and address;
    (ii) The statement ``Manufactured in ----'' (inserting the month and 
year that the guard was manufactured); and,
    (iii) The letters ``DOT'', constituting a certification by the guard 
manufacturer that the guard conforms to all requirements of FMVSS No. 
223.

[[Page 427]]

    (b)(1) Requirements for motor vehicles manufactured after December 
31, 1952 (except trailers or semitrailers manufactured on or after 
January 26, 1998). Each motor vehicle manufactured after December 31, 
1952, (except truck tractors, pole trailers, pulpwood trailers, or 
vehicles in driveaway-towaway operations) in which the vertical distance 
between the rear bottom edge of the body (or the chassis assembly if the 
chassis is the rearmost part of the vehicle) and the ground is greater 
than 76.2 cm (30 inches) when the motor vehicle is empty, shall be 
equipped with a rear impact guard(s). The rear impact guard(s) must be 
installed and maintained in such a manner that:
    (i) The vertical distance between the bottom of the guard(s) and the 
ground does not exceed 76.2 cm (30 inches) when the motor vehicle is 
empty;
    (ii) The maximum lateral distance between the closest points between 
guards, if more than one is used, does not exceed 61 cm (24 inches);
    (iii) The outermost surfaces of the horizontal member of the guard 
are no more than 45.7 cm (18 inches) from each side extremity of the 
motor vehicle;
    (iv) The impact guard(s) are no more than 61 cm (24 inches) forward 
of the rear extremity of the motor vehicle.
    (2) Construction and attachment. The rear impact guard(s) must be 
substantially constructed and attached by means of bolts, welding, or 
other comparable means.
    (3) Vehicle components and structures that may be used to satisfy 
the requirements of paragraph (b) of this section. Low chassis vehicles, 
special purpose vehicles, or wheels back vehicles constructed and 
maintained so that the body, chassis, or other parts of the vehicle 
provide the rear end protection comparable to impact guard(s) conforming 
to the requirements of paragraph (b)(1) of this section shall be 
considered to be in compliance with those requirements.

[64 FR 47708, Sept. 1, 1999, as amended at 67 FR 61824, Oct. 2, 2002]

Sec. 393.87  Warning flags on projecting loads.

    (a) Any commercial motor vehicle transporting a load which extends 
beyond the sides by more than 102 mm (4 inches) or more than 1,219 mm (4 
feet) beyond the rear must have the extremities of the load marked with 
red or orange fluorescent warning flags. Each warning flag must be at 
least 457 mm (18 inches) square.
    (b) Position of flags. There must be a single flag at the extreme 
rear if the projecting load is two feet wide or less. Two warning flags 
are required if the projecting load is wider than two feet. Flags must 
be located to indicate maximum width of loads which extend beyond the 
sides and/or rear of the vehicle.

[70 FR 48054, Aug. 15, 2005]

Sec. 393.88  Television receivers.

    Any motor vehicle equipped with a television viewer, screen or other 
means of visually receiving a television broadcast shall have the viewer 
or screen located in the motor vehicle at a point to the rear of the 
back of the driver's seat if such viewer or screen is in the same 
compartment as the driver and the viewer or screen shall be so located 
as not to be visible to the driver, while he/she is driving the motor 
vehicle. The operating controls for the television receiver shall be so 
located that the driver cannot operate them without leaving the driver's 
seat.

Sec. 393.89  Buses, driveshaft protection.

    Any driveshaft extending lengthways under the floor of the passenger 
compartment of a bus shall be protected by means of at least one guard 
or bracket at that end of the shaft which is provided with a sliding 
connection (spline or other such device) to prevent the whipping of the 
shaft in the event of failure thereof or of any of its component parts. 
A shaft contained within a torque tube shall not require any such 
device.

[33 FR 19735, Dec. 25, 1968, as amended at 53 FR 49402, Dec. 7, 1988]

Sec. 393.90  Buses, standee line or bar.

    Except as provided below, every bus, which is designed and 
constructed so as to allow standees, shall be plainly marked with a line 
of contrasting color at least 2 inches wide or equipped with some other 
means so as to indicate to any person that he/she is prohibited

[[Page 428]]

from occupying a space forward of a perpendicular plane drawn through 
the rear of the driver's seat and perpendicular to the longitudinal axis 
of the bus. Every bus shall have clearly posted at or near the front, a 
sign with letters at least one-half inch high stating that it is a 
violation of the Federal Motor Carrier Safety Administration's 
regulations for a bus to be operated with persons occupying the 
prohibited area. The requirements of this section shall not apply to any 
bus being transported in driveaway-towaway operation or to any level of 
the bus other that the level in which the driver is located nor shall 
they be construed to prohibit any seated person from occupying permanent 
seats located in the prohibited area provided such seats are so located 
that persons sitting therein will not interfere with the driver's safe 
operation of the bus.

Sec. 393.91  Buses, aisle seats prohibited.

    No bus shall be equipped with aisle seats unless such seats are so 
designed and installed as to automatically fold and leave a clear aisle 
when they are unoccupied. No bus shall be operated if any seat therein 
is not securely fastened to the vehicle.

[53 FR 49402, Dec. 7, 1988]

Sec. 393.92  [Reserved]

Sec. 393.93  Seats, seat belt assemblies, and seat belt assembly 
          anchorages.

    (a) Buses--(1) Buses manufactured on or after January 1, 1965, and 
before July 1, 1971. After June 30, 1972, every bus manufactured on or 
after January 1, 1965, and before July 1, 1971, must be equipped with a 
Type 1 or Type 2 seat belt assembly that conforms to Federal Motor 
Vehicle Safety Standard No. 209 \1\ (Sec. 571.209) installed at the 
driver's seat and seat belt assembly anchorages that conform to the 
location and geometric requirements of Federal Motor Vehicle Safety 
Standard No. 210 \1\ (Sec. 571.210) for that seat belt assembly.
---------------------------------------------------------------------------

    \1\ Individual copies of Federal Motor Vehicle Safety Standards may 
be obtained from the National Highway Traffic Safety Administration. 
Nassif Building, 400 Seventh Street SW., Washington, D.C. 20590.
---------------------------------------------------------------------------

    (2) Buses manufactured on or after July 1, 1971. Every bus 
manufactured on or after July 1, 1971, must conform to the requirements 
of Federal Motor Vehicle Safety Standard No. 208 \1\ (Sec. 571.208) 
(relating to installation of seat belt assemblies) and Federal Motor 
Vehicle Safety Standard No. 210 \1\ (Sec. 571.210) (relating to 
installation of seat belt assembly anchorages).
    (3) Buses manufactured on or after January 1, 1972. Every bus 
manufactured on or after January 1, 1972, must conform to the 
requirements of Federal Motor Vehicle Safety Standard No. 207 \1\ (Sec. 
571.207) (relating to seating systems).
    (b) Trucks and truck tractors--(1) Trucks and truck tractors 
manufactured on and after January 1, 1965, and before July 1, 1971. 
Except as provided in paragraph (d) of this section, after June 30, 
1972, every truck and truck tractor manufactured on or after January 1, 
1965, and before July 1, 1971, must be equipped with a Type 1 or Type 2 
seat belt assembly that conforms to Federal Motor Vehicle Safety 
Standard No. 209 (Sec. 571.209) installed at the driver's seat and at 
the right front outboard seat, if the vehicle has one, and seat belt 
assembly anchorages that conform to the location and geometric 
requirements of Federal Motor Vehicle Safety Standard No. 210 (Sec. 
571.210) for each seat belt assembly that is required by this 
subparagraph.
    (2) Trucks and truck tractors manufactured on or after July 1, 1971. 
Every truck and truck tractor manufactured on or after July 1, 1971, 
except a truck or truck tractor being transported in driveaway-towaway 
operation and having an incomplete vehicle seating and cab 
configuration, must conform to the requirements of Federal Motor Vehicle 
Safety Standard No. 208 \1\ (Sec. 571.208) (relating to installation of 
seat belt assemblies) and Federal Motor Vehicle Safety Standard No. 210 
\1\ (Sec. 571.210) (relating to installation of seat belt assembly 
anchorages).
---------------------------------------------------------------------------

    \1\ See footnote to Sec. 393.93(a).
---------------------------------------------------------------------------

    (3) Trucks and truck tractors manufactured on or after January 1, 
1972. Every truck and truck tractor manufactured on or after January 1, 
1972, except a

[[Page 429]]

truck or truck tractor being transported in driveaway-towaway operation 
and having an incomplete vehicle seating and cab configuration, must 
conform to the requirements of Federal Motor Vehicle Safety Standard No. 
207 \1\ (Sec. 571.207) (relating to seating systems).
    (c) Effective date of standards. Whenever paragraph (a) or (b) of 
this section requires conformity to a Federal Motor Vehicle Safety 
Standard, the vehicle or equipment must conform to the version of the 
Standard that is in effect on the date the vehicle is manufactured or on 
the date the vehicle is modified to conform to the requirements of 
paragraph (a) or (b) of this section, whichever is later.
    (d) Trucks and truck tractors manufactured on or after January 1, 
1965, and before July 1, 1971, and operated in the State of Hawaii, must 
comply with the provisions of paragraph (b) of this section on and after 
January 1, 1976.

[35 FR 16839, Oct. 30, 1970, as amended at 39 FR 32561, Sept. 9, 1974; 
40 FR 32336, Aug. 1, 1975]

Sec. 393.94  Interior noise levels in power units.

    (a) Applicability of this section. The interior noise level 
requirements apply to all trucks, truck-tractors, and buses.
    (b) General rule. The interior sound level at the driver's seating 
position of a motor vehicle must not exceed 90 dB(A) when measured in 
accordance with paragraph (c) of this section.
    (c) Test procedure. (1) Park the vehicle at a location so that no 
large reflecting surfaces, such as other vehicles, signboards, 
buildings, or hills, are within 50 feet of the driver's seating 
position.
    (2) Close all vehicle doors, windows, and vents. Turn off all power-
operated accessories.
    (3) Place the driver in his/her normal seated position at the 
vehicle's controls. Evacuate all occupants except the driver and the 
person conducting the test.
    (4) The sound level meters used to determine compliance with the 
requirements of this section must meet the American National Standards 
Institute ``Specification for Sound Level Meters,'' ANSI S1.4--1983. 
(See Sec. 393.7(b) for information on the incorporation by reference 
and availability of this document.)
    (5) Locate the microphone, oriented vertically upward, 6 inches to 
the right of, in the same plane as, and directly in line with, the 
driver's right ear.
    (6) With the vehicle's transmission in neutral gear, accelerate its 
engine to either its maximum governed engine speed, if it is equipped 
with an engine governor, or its speed at its maximum rated horsepower, 
if it is not equipped with an engine governor. Stabilize the engine at 
that speed.
    (7) Observe the A-weighted sound level reading on the meter for the 
stabilized engine speed condition. Record that reading, if the reading 
has not been influenced by extraneous noise sources such as motor 
vehicles operating on adjacent roadways.
    (8) Return the vehicle's engine speed to idle and repeat the 
procedures specified in paragraphs (c) (6) and (7) of this section until 
two maximum sound levels within 2 dB of each other are recorded. 
Numerically average those two maximum sound level readings.
    (9) The average obtained in accordance with paragraph (c)(8) of this 
section is the vehicle's interior sound level at the driver's seating 
position for the purpose of determining whether the vehicle conforms to 
the rule in paragraph (b) of this section. How ever, a 2 dB tolerance 
over the sound level limitation specified in that paragraph is permitted 
to allow for variations in test conditions and variations in the 
capabilities of meters.
    (10) If the motor vehicle's engine radiator fan drive is equipped 
with a clutch or similar device that automatically either reduces the 
rotational speed of the fan or completely disengages the fan from its 
power source in response to reduced engine cooling loads the vehicle may 
be parked before testing with its engine running at high idle or any 
other speed the operator may choose, for sufficient time but not more 
than 10 minutes, to permit the engine radiator fan to automatically 
disengage.

[38 FR 30881, Nov. 8, 1973, as amended at 40 FR 32336, Aug. 1, 1975; 41 
FR 28268, July 9, 1976; 70 FR 48054, Aug. 15, 2005]

[[Page 430]]

                      Subpart H_Emergency Equipment

Sec. 393.95  Emergency equipment on all power units.

    Each truck, truck tractor, and bus (except those towed in driveaway-
towaway operations) must be equipped as follows:
    (a) Fire Extinguishers. (1) Minimum ratings: (i) A power unit that 
is used to transport hazardous materials in a quantity that requires 
placarding (See Sec. 177.823 of this title) must be equipped with a 
fire extinguisher having an Underwriters' Laboratories rating of 10 B:C 
or more.
    (ii) A power unit that is not used to transport hazardous materials 
must be equipped with either:
    (A) A fire extinguisher having an Underwriters' Laboratories rating 
of 5 B:C or more; or
    (B) Two fire extinguishers, each of which has an Underwriters' 
Laboratories rating of 4 B:C or more.
    (2) Labeling and marking. Each fire extinguisher required by this 
section must be labeled or marked by the manufacturer with its 
Underwriters' Laboratories rating.
    (3) Visual Indicators. The fire extinguisher must be designed, 
constructed, and maintained to permit visual determination of whether it 
is fully charged.
    (4) Condition, location, and mounting. The fire extinguisher(s) must 
be filled and located so that it is readily accessible for use. The 
extinguisher(s) must be securely mounted to prevent sliding, rolling, or 
vertical movement relative to the motor vehicle.
    (5) Extinguishing agents. The fire extinguisher must use an 
extinguishing agent that does not need protection from freezing. 
Extinguishing agents must comply with the toxicity provisions of the 
Environmental Protection Agency's Significant New Alternatives Policy 
(SNAP) regulations under 40 CFR Part 82, Subpart G.
    (b) Spare fuses. Power units for which fuses are needed to operate 
any required parts and accessories must have at least one spare fuse for 
each type/size of fuse needed for those parts and accessories.
    (c)-(e) [Reserved]
    (f) Warning devices for stopped vehicles. Except as provided in 
paragraph (g) of this section, one of the following options must be 
used:
    (1) Three bidirectional emergency reflective triangles that conform 
to the requirements of Federal Motor Vehicle Safety Standard No. 125, 
Sec. 571.125 of this title; or
    (2) At least 6 fusees or 3 liquid-burning flares. The vehicle must 
have as many additional fusees or liquid-burning flares as are necessary 
to satisfy the requirements of Sec. 392.22.
    (3) Other warning devices may be used in addition to, but not in 
lieu of, the required warning devices, provided those warning devices do 
not decrease the effectiveness of the required warning devices.
    (g) Restrictions on the use of flame-producing devices. Liquid-
burning flares, fusees, oil lanterns, or any signal produced by a flame 
shall not be carried on any commercial motor vehicle transporting 
Division 1.1, 1.2, 1.3 (explosives) hazardous materials; any cargo tank 
motor vehicle used for the transportation of Division 2.1 (flammable 
gas) or Class 3 (flammable liquid) hazardous materials whether loaded or 
empty; or any commercial motor vehicle using compressed gas as a motor 
fuel.
    (h)--(i) [Reserved]
    (j) Requirements for fusees and liquid-burning flares. Each fusee 
shall be capable of burning for 30 minutes, and each liquid-burning 
flare shall contain enough fuel to burn continuously for at least 60 
minutes. Fusees and liquid-burning flares shall conform to the 
requirements of Underwriters Laboratories, Inc., UL No. 912, Highway 
Emergency Signals, Fourth Edition, July 30, 1979, (with an amendment 
dated November 9, 1981). (See Sec. 393.7(c) for information on the 
incorporation by reference and availability of this document.) Each 
fusee and liquid-burning flare shall be marked with the UL symbol in 
accordance with the requirements of UL 912.
    (k) Requirements for red flags. Red flags shall be not less than 12 
inches square, with standards adequate to

[[Page 431]]

maintain the flags in an upright position.

(49 U.S.C. 304, 1655; 49 CFR 1.48(b) and 301.60)

[33 FR 19735, Dec. 25, 1968, as amended at 35 FR 13019, Aug. 15, 1970; 
35 FR 14619, Sept. 18, 1970; 37 FR 17176, Aug. 25, 1972; 40 FR 10685, 
Mar. 7, 1975; 41 FR 53031, Dec. 3, 1976; 47 FR 47837, Oct. 28, 1982; 59 
FR 34712, July 6, 1994; 67 FR 61225, Sept. 27, 2002; 70 FR 48054, Aug. 
15, 2005]

         Subpart I_Protection Against Shifting and Falling Cargo

    Source: 67 FR 61225, Sept. 27, 2002, unless otherwise noted.

Sec. 393.100  Which types of commercial motor vehicles are subject to 
          the cargo securement standards of this subpart, and what 
          general requirements apply?

    (a) Applicability. The rules in this subpart are applicable to 
trucks, truck tractors, semitrailers, full trailers, and pole trailers.
    (b) Prevention against loss of load. Each commercial motor vehicle 
must, when transporting cargo on public roads, be loaded and equipped, 
and the cargo secured, in accordance with this subpart to prevent the 
cargo from leaking, spilling, blowing or falling from the motor vehicle.
    (c) Prevention against shifting of load. Cargo must be contained, 
immobilized or secured in accordance with this subpart to prevent 
shifting upon or within the vehicle to such an extent that the vehicle's 
stability or maneuverability is adversely affected.

Sec. 393.102  What are the minimum performance criteria for cargo 
          securement devices and systems?

    (a) Performance criteria. Cargo securement devices and systems must 
be capable of withstanding the following three forces, applied 
separately:
    (1) 0.8 g deceleration in the forward direction;
    (2) 0.5 g acceleration in the rearward direction; and
    (3) 0.5 g acceleration in a lateral direction.
    (b) Performance criteria for devices to prevent vertical movement of 
loads that are not contained within the structure of the vehicle. 
Securement systems must provide a downward force equivalent to at least 
20 percent of the weight of the article of cargo if the article is not 
fully contained within the structure of the vehicle. If the article is 
fully contained within the structure of the vehicle, it may be secured 
in accordance with Sec. 393.106(b).
    (c) Prohibition on exceeding working load limits. Cargo securement 
devices and systems must be designed, installed, and maintained to 
ensure that the maximum forces acting on the devices or systems do not 
exceed the working load limit for the devices under the conditions 
listed in paragraphs (a) and (b) of this section.
    (d) Equivalent means of securement. Cargo that is immobilized, or 
secured in accordance with the applicable requirements of Sec. Sec. 
393.104 through 393.136, is considered as meeting the performance 
criteria of this section.

Sec. 393.104  What standards must cargo securement devices and systems 
          meet in order to satisfy the requirements of this subpart?

    (a) General. All devices and systems used to secure cargo to or 
within a vehicle must be capable of meeting the requirements of Sec. 
393.102.
    (b) Prohibition on the use of damaged securement devices. All 
vehicle structures, systems, parts, and components used to secure cargo 
must be in proper working order when used to perform that function with 
no damaged or weakened components that will adversely effect their 
performance for cargo securement purposes, including reducing the 
working load limit, and must not have any cracks or cuts.
    (c) Vehicle structures and anchor points. Vehicle structures, 
floors, walls, decks, tiedown anchor points, headerboards, bulkheads, 
stakes, posts and associated mounting pockets used to contain or secure 
articles of cargo must be strong enough to meet the performance criteria 
of Sec. 393.102, with no damaged or weakened components that will 
adversely effect their performance for cargo securement purposes, 
including reducing the working load limit, and must not have any cracks 
or cuts.
    (d) Material for dunnage, chocks, cradles, shoring bars, blocking 
and bracing. Material used as dunnage or dunnage

[[Page 432]]

bags, chocks, cradles, shoring bars, or used for blocking and bracing, 
must not have damage or defects which would compromise the effectiveness 
of the securement system.
    (e) Manufacturing standards for tiedown assemblies. Tiedown 
assemblies (including chains, wire rope, steel strapping, synthetic 
webbing, and cordage) and other attachment or fastening devices used to 
secure articles of cargo to, or in, commercial motor vehicles must 
conform to the following applicable standards:

[[Page 433]]



----------------------------------------------------------------------------------------------------------------
               An assembly component of . . .                               Must conform to . . .
----------------------------------------------------------------------------------------------------------------
(1) Steel strapping 1, 2...................................  Standard Specification for Strapping, Flat Steel
                                                              and Seals, American Society for Testing and
                                                              Materials (ASTM) D3953-97, February 1998.\4\
(2) Chain..................................................  National Association of Chain Manufacturers' Welded
                                                              Steel Chain Specifications, November 15, 1999.\4\
(3) Webbing................................................  Web Sling and Tiedown Association's Recommended
                                                              Standard Specification for Synthetic Web Tiedowns,
                                                              WSTDA-T1, 1998.\4\
(4) Wire rope \3\..........................................  Wire Rope Technical Board's Wire Rope Users Manual,
                                                              2nd Edition, November 1985.\4\
(5) Cordage................................................  Cordage Institute rope standard:
                                                                (i) PETRS-2, Polyester Fiber Rope, three-Strand
                                                                 and eight-Strand Constructions, January 1993;
                                                                 \4\
                                                                (ii) PPRS-2, Polypropylene Fiber Rope, three-
                                                                 Strand and eight-Strand Constructions, August
                                                                 1992; \4\
                                                                (iii) CRS-1, Polyester/Polypropylene Composite
                                                                 Rope Specifications, three-Strand and eight-
                                                                 Strand Standard Construction, May 1979; \4\
                                                                (iv) NRS-1, Nylon Rope Specifications, three-
                                                                 Strand and eight-Strand Standard Construction,
                                                                 May 1979; \4\ and
                                                                (v) C-1, Double Braided Nylon Rope
                                                                 Specifications DBN, January 1984.\4\
----------------------------------------------------------------------------------------------------------------
\1\ Steel strapping not marked by the manufacturer with a working load limit will be considered to have a
  working load limit equal to one-fourth of the breaking strength listed in ASTM D3953-97.
\2\ Steel strapping 25.4 mm (1 inch) or wider must have at least two pairs of crimps in each seal and, when an
  end-over-end lap joint is formed, must be sealed with at least two seals.
\3\ Wire rope which is not marked by the manufacturer with a working load limit shall be considered to have a
  working load limit equal to one-fourth of the nominal strength listed in the manual.
\4\ See Sec. 393.7 for information on the incorporation by reference and availability of this document.


[[Page 434]]

    (f) Use of tiedowns. (1) Tiedowns and securing devices must not 
contain knots.
    (2) If a tiedown is repaired, it must be repaired in accordance with 
the applicable standards in paragraph (e) of this section, or the 
manufacturer's instructions.
    (3) Each tiedown must be attached and secured in a manner that 
prevents it from becoming loose, unfastening, opening or releasing while 
the vehicle is in transit.
    (4) All tiedowns and other components of a cargo securement system 
used to secure loads on a trailer equipped with rub rails, must be 
located inboard of the rub rails whenever practicable.
    (5) Edge protection must be used whenever a tiedown would be subject 
to abrasion or cutting at the point where it touches an article of 
cargo. The edge protection must resist abrasion, cutting and crushing.

Sec. 393.106  What are the general requirements for securing articles 
          of cargo?

    (a) Applicability. The rules in this section are applicable to the 
transportation of all types of articles of cargo, except commodities in 
bulk that lack structure or fixed shape (e.g., liquids, gases, grain, 
liquid concrete, sand, gravel, aggregates) and are transported in a 
tank, hopper, box or similar device that forms part of the structure of 
a commercial motor vehicle. The rules in this section apply to the cargo 
types covered by the commodity-specific rules of Sec. 393.116 through 
Sec. 393.136. The commodity-specific rules take precedence over the 
general requirements of this section when additional requirements are 
given for a commodity listed in those sections.
    (b) General. Cargo must be firmly immobilized or secured on or 
within a vehicle by structures of adequate strength, dunnage or dunnage 
bags, shoring bars, tiedowns or a combination of these.
    (c) Cargo placement and restraint. (1) Articles of cargo that are 
likely to roll must be restrained by chocks, wedges, a cradle or other 
equivalent means to prevent rolling. The means of preventing rolling 
must not be capable of becoming unintentionally unfastened or loose 
while the vehicle is in transit.
    (2) Articles or cargo placed beside each other and secured by 
transverse tiedowns must either:
    (i) Be placed in direct contact with each other, or
    (ii) Be prevented from shifting towards each other while in transit.
    (d) Minimum strength of cargo securement devices and systems. The 
aggregate working load limit of any securement system used to secure an 
article or group of articles against movement must be at least one-half 
times the weight of the article or group of articles. The aggregate 
working load limit is the sum of:
    (1) One-half of the working load limit of each associated connector 
or attachment mechanism used to secure a part of the article of cargo to 
the vehicle; and
    (2) One-half of the working load limit for each end section of a 
tiedown that is attached to an anchor point.

[67 FR 61225, Sept. 27, 2002, as amended at 68 FR 56208, Sept. 30, 2003]

Sec. 393.108  How is the working load limit of a tiedown determined?

    (a) The working load limit (WLL) of a tiedown, associated connector 
or attachment mechanism is the lowest working load limit of any of its 
components (including tensioner), or the working load limit of the 
anchor points to which it is attached, whichever is less.
    (b) The working load limits of tiedowns may be determined by using 
either the tiedown manufacturer's markings or by using the tables in 
this section. The working load limits listed in the tables are to be 
used when the tiedown material is not marked by the manufacturer with 
the working load limit. Tiedown materials which are marked by the 
manufacturer with working load limits that differ from the tables, shall 
be considered to have a working load limit equal to the value for which 
they are marked.
    (c) Synthetic cordage (e.g., nylon, polypropylene, polyester) which 
is not marked or labeled to enable identification of its composition or 
working load limit shall be considered to have a

[[Page 435]]

working load limit equal to that for polypropylene fiber rope.
    (d) Welded steel chain which is not marked or labeled to enable 
identification of its grade or working load limit shall be considered to 
have a working load limit equal to that for grade 30 proof coil chain.
    (e)(1) Wire rope which is not marked by the manufacturer with a 
working load limit shall be considered to have a working load limit 
equal to one-fourth of the nominal strength listed in the Wire Rope 
Users Manual.
    (2) Wire which is not marked or labeled to enable identification of 
its construction type shall be considered to have a working load limit 
equal to that for 6 x 37, fiber core wire rope.
    (f) Manila rope which is not marked by the manufacturer with a 
working load limit shall be considered to have a working load limit 
based on its diameter as provided in the tables of working load limits.
    (g) Friction mats which are not marked or rated by the manufacturer 
shall be considered to provide resistance to horizontal movement equal 
to 50 percent of the weight placed on the mat.

                                                                Tables to Sec. 393.108
                                                           [Working Load Limits (WLL), Chain]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                   WLL in kg (pounds)
                                                               -----------------------------------------------------------------------------------------
                       Size mm (inches)                          Grade 30 proof     Grade 43 high       Grade 70
                                                                      coil              test            transport      Grade 80 alloy    Grade 100 alloy
--------------------------------------------------------------------------------------------------------------------------------------------------------
1. 7 (1/4)....................................................       580 (1,300)     1,180 (2,600)     1,430 (3,150)     1,570 (3,500)     1,950 (4,300)
2. 8 (5/16)...................................................       860 (1,900)     1,770 (3,900)     2,130 (4,700)     2,000 (4,500)     2,600 (5,700)
3. 10 (3/8)...................................................     1,200 (2,650)     2,450 (5,400)     2,990 (6,600)     3,200 (7,100)     4,000 (8,800)
4. 11 (7/16)..................................................     1,680 (3,700)     3,270 (7,200)     3,970 (8,750)
5. 13 (1/2)...................................................     2,030 (4,500)     4,170 (9,200)    5,130 (11,300)    5,400 (12,000)    6,800 (15,000)
6. 16 (5/8)...................................................     3,130 (6,900)    5,910 (13,000)    7,170 (15,800)    8,200 (18,100)   10,300 (22,600)
Chain Mark Examples:
    Example 1.................................................                 3                 4                 7                 8                10
    Example 2.................................................                30                43                70                80               100
    Example 3.................................................               300               430               700               800              1000
--------------------------------------------------------------------------------------------------------------------------------------------------------


                            Synthetic Webbing
------------------------------------------------------------------------
                   Width mm (inches)                     WLL kg (pounds)
------------------------------------------------------------------------
45 (1\3/4\)...........................................       790 (1,750)
50 (2)................................................       910 (2,000)
75 (3)................................................     1,360 (3,000)
100 (4)...............................................     1,810 (4,000)
------------------------------------------------------------------------


                     Wire Rope (6 x 37, Fiber Core)
------------------------------------------------------------------------
                 Diameter mm (inches)                    WLL kg (pounds)
------------------------------------------------------------------------
7 (1/4)...............................................       640 (1,400)
8 (5/16)..............................................       950 (2,100)
10 (3/8)..............................................     1,360 (3,000)
11 (7/16).............................................     1,860 (4,100)
13 (1/2)..............................................     2,400 (5,300)
16 (5/8)..............................................     3,770 (8,300)
20 (3/4)..............................................    4,940 (10,900)
22 (7/8)..............................................    7,300 (16,100)
25 (1)................................................    9,480 (20,900)
------------------------------------------------------------------------


                               Manila Rope
------------------------------------------------------------------------
                 Diameter mm (inches)                    WLL kg (pounds)
------------------------------------------------------------------------
10 (3/8)..............................................          90 (205)
11 (7/16).............................................         120 (265)
13 (1/2)..............................................         150 (315)
16 (5/8)..............................................         210 (465)
20 (3/4)..............................................         290 (640)
25 (1)................................................       480 (1,050)
------------------------------------------------------------------------


   Polypropylene Fiber Rope WLL (3-Strand and 8-Strand Constructions)
------------------------------------------------------------------------
                 Diameter mm (inches)                    WLL kg (pounds)
------------------------------------------------------------------------
10 (3/8)..............................................         180 (400)
11 (7/16).............................................         240 (525)
13 (1/2)..............................................         280 (625)
16 (5/8)..............................................         420 (925)
20 (3/4)..............................................       580 (1,275)
25 (1)................................................       950 (2,100)
------------------------------------------------------------------------


     Polyester Fiber Rope WLL (3-Strand and 8-Strand Constructions)
------------------------------------------------------------------------
                 Diameter mm (inches)                    WLL kg (pounds)
------------------------------------------------------------------------
10 (3/8)..............................................         250 (555)
11 (7/16).............................................         340 (750)
13 (1/2)..............................................         440 (960)
16 (5/8)..............................................       680 (1,500)
20 (3/4)..............................................       850 (1,880)
25 (1)................................................     1,500 (3,300)
------------------------------------------------------------------------


                               Nylon Rope
------------------------------------------------------------------------
                 Diameter mm (inches)                    WLL kg (pounds)
------------------------------------------------------------------------
10 (3/8)..............................................         130 (278)
11 (7/16).............................................         190 (410)
13 (1/2)..............................................         240 (525)
16 (5/8)..............................................         420 (935)
20 (3/4)..............................................       640 (1,420)

[[Page 436]]


25 (1)................................................     1,140 (2,520)
------------------------------------------------------------------------


                        Double Braided Nylon Rope
------------------------------------------------------------------------
                 Diameter mm (inches)                    WLL kg (pounds)
------------------------------------------------------------------------
10 (3/8)..............................................         150 (336)
11 (7/16).............................................         230 (502)
13 (1/2)..............................................         300 (655)
16 (5/8)..............................................       510 (1,130)
20 (3/4)..............................................       830 (1,840)
25 (1)................................................     1,470 (3,250)
------------------------------------------------------------------------


                             Steel Strapping
------------------------------------------------------------------------
             Width x thickness mm (inches)               WLL kg (pounds)
------------------------------------------------------------------------
31.7 x .74 (1 1/4 x 0.029)............................       540 (1,190)
31.7 x .79 (1\1/4\ x 0.031)...........................       540 (1,190)
31.7 x .89 (1\1/4\ x 0.035)...........................       540 (1,190)
31.7 x 1.12 (1\1/4\ x 0.044)..........................       770 (1,690)
31.7 x 1.27 (1\1/4\ x 0.05)...........................       770 (1,690)
31.7 x 1.5 (1\1/4\ x 0.057)...........................       870 (1,925)
50.8 x 1.12 (2 x 0.044)...............................     1,200 (2,650)
50.8 x 1.27 (2 x 0.05)................................     1,200 (2,650)
------------------------------------------------------------------------

Sec. 393.110  What else do I have to do to determine the minimum number 
          of tiedowns?

    (a) In addition to the requirements of Sec. 393.106, the minimum 
number of tiedowns required to secure an article or group of articles 
against movement depends on the length of the article(s) being secured, 
and the requirements of paragraphs (b) and (c) of this section.
    (b) When an article is not blocked or positioned to prevent movement 
in the forward direction by a headerboard, bulkhead, other cargo that is 
positioned to prevent movement, or other appropriate blocking devices, 
it must be secured by at least:
    (1) One tiedown for articles 5 feet (1.52 meters) or less in length, 
and 1,100 pounds (500 kg) or less in weight;
    (2) Two tiedowns if the article is:
    (i) 5 feet (1.52 meters) or less in length and more than 1,100 
pounds (500 kg) in weight; or
    (ii) Longer than 5 feet (1.52 meters) but less than or equal to 10 
feet (3.04 meters) in length, irrespective of the weight.
    (3) Two tiedowns if the article is longer than 10 feet (3.04 
meters), and one additional tiedown for every 10 feet (3.04 meters) of 
article length, or fraction thereof, beyond the first 10 feet (3.04 
meters) of length.
    (c) If an individual article is required to be blocked, braced or 
immobilized to prevent movement in the forward direction by a 
headerboard, bulkhead, other articles which are adequately secured or by 
an appropriate blocking or immobilization method, it must be secured by 
at least one tiedown for every 3.04 meters (10 feet) or article length, 
or fraction thereof.
    (d) Special rule for special purpose vehicles. The rules in this 
section do not apply to a vehicle transporting one or more articles of 
cargo such as, but not limited to, machinery or fabricated structural 
items (e.g., steel or concrete beams, crane booms, girders, and trusses, 
etc.) which, because of their design, size, shape, or weight, must be 
fastened by special methods. However, any article of cargo carried on 
that vehicle must be securely and adequately fastened to the vehicle.

Sec. 393.112  Must a tiedown be adjustable?

    Each tiedown, or its associated connectors, or its attachment 
mechanisms must be designed, constructed, and maintained so the driver 
of an in-transit commercial motor vehicle can tighten them. However, 
this requirement does not apply to the use of steel strapping.

Sec. 393.114  What are the requirements for front end structures used 
          as part of a cargo securement system?

    (a) Applicability. The rules in this section are applicable to 
commercial motor vehicles transporting articles of cargo that are in 
contact with the front end structure of the vehicle. The front end 
structure on these cargo-carrying vehicles must meet the performance 
requirements of this section.
    (b) Height and width. (1) The front end structure must extend either 
to a height of 4 feet above the floor of the vehicle or to a height at 
which it blocks forward movement of any item of article of cargo being 
carried on the vehicle, whichever is lower.
    (2) The front end structure must have a width which is at least 
equal to the width of the vehicle or which blocks forward movement of 
any article of cargo being transported on the vehicle, whichever is 
narrower.

[[Page 437]]

    (c) Strength. The front end structure must be capable of 
withstanding the following horizontal forward static load:
    (1) For a front end structure less than 6 feet in height, a 
horizontal forward static load equal to one-half (0.5) of the weight of 
the articles of cargo being transported on the vehicle uniformly 
distributed over the entire portion of the front end structure that is 
within 4 feet above the vehicle's floor or that is at or below a height 
above the vehicle's floor at which it blocks forward movement of any 
article of the vehicle's cargo, whichever is less; or
    (2) For a front end structure 6 feet in height or higher, a 
horizontal forward static load equal to four-tenths (0.4) of the weight 
of the articles of cargo being transported on the vehicle uniformly 
distributed over the entire front end structure.
    (d) Penetration resistance. The front end structure must be 
designed, constructed, and maintained so that it is capable of resisting 
penetration by any article of cargo that contacts it when the vehicle 
decelerates at a rate of 20 feet per second, per second. The front end 
structure must have no aperture large enough to permit any article of 
cargo in contact with the structure to pass through it.
    (e) Substitute devices. The requirements of this section may be met 
by the use of devices performing the same functions as a front end 
structure, if the devices are at least as strong as, and provide 
protection against shifting articles of cargo at least equal to, a front 
end structure which conforms to those requirements.

           Specific Securement Requirements by Commodity Type

Sec. 393.116  What are the rules for securing logs?

    (a) Applicability. The rules in this section are applicable to the 
transportation of logs with the following exceptions:
    (1) Logs that are unitized by banding or other comparable means may 
be transported in accordance with the general cargo securement rules of 
Sec. Sec. 393.100 through 393.114.
    (2) Loads that consist of no more than four processed logs may be 
transported in accordance with the general cargo securement rules of 
Sec. Sec. 393.100 through 393.114.
    (3) Firewood, stumps, log debris and other such short logs must be 
transported in a vehicle or container enclosed on both sides, front, and 
rear and of adequate strength to contain them. Longer logs may also be 
so loaded.
    (b) Components of a securement system. (1) Logs must be transported 
on a vehicle designed and built, or adapted, for the transportation of 
logs. Any such vehicle must be fitted with bunks, bolsters, stakes or 
standards, or other equivalent means, that cradle the logs and prevent 
them from rolling.
    (2) All vehicle components involved in securement of logs must be 
designed and built to withstand all anticipated operational forces 
without failure, accidental release or permanent deformation. Stakes or 
standards that are not permanently attached to the vehicle must be 
secured in a manner that prevents unintentional separation from the 
vehicle in transit.
    (3) Tiedowns must be used in combination with the stabilization 
provided by bunks, stakes and bolsters to secure the load.
    (c) Use of securement system. (1) Logs must be solidly packed, and 
the outer bottom logs must be in contact with and resting solidly 
against the bunks, bolsters, stakes or standards.
    (2) Each outside log on the side of a stack of logs must touch at 
least two stakes, bunks, bolsters, or standards. If one end does not 
actually touch a stake, it must rest on other logs in a stable manner 
and must extend beyond the stake, bunk, bolster or standard.
    (3) The center of the highest outside log on each side or end must 
be below the top of each stake, bunk or standard.
    (4) Each log that is not held in place by contact with other logs or 
the stakes, bunks, or standards must be held in place by a tiedown. 
Additional tiedowns or securement devices must be used when the 
condition of the wood results in such low friction between logs that 
they are likely to slip upon each other.

[[Page 438]]

    (d) Securement of shortwood logs loaded crosswise on frame, rail and 
flatbed vehicles. In addition to the requirements of paragraphs (b) and 
(c) of this section, each stack of logs loaded crosswise must meet the 
following rules:
    (1) In no case may the end of a log in the lower tier extend more 
than one-third of the log's total length beyond the nearest supporting 
structure on the vehicle.
    (2) When only one stack of shortwood is loaded crosswise, it must be 
secured with at least two tiedowns. The tiedowns must attach to the 
vehicle frame at the front and rear of the load, and must cross the load 
in this direction.
    (3) When two tiedowns are used, they must be positioned at 
approximately one-third and two-thirds of the length of the logs.
    (4) A vehicle that is more than 10 meters (33 feet) long must be 
equipped with center stakes, or comparable devices, to divide it into 
sections approximately equal in length. Where a vehicle is so divided, 
each tiedown must secure the highest log on each side of the center 
stake, and must be fastened below these logs. It may be fixed at each 
end and tensioned from the middle, or fixed in the middle and tensioned 
from each end, or it may pass through a pulley or equivalent device in 
the middle and be tensioned from one end.
    (5) Any structure or stake that is subjected to an upward force when 
the tiedowns are tensioned must be anchored to resist that force.
    (6) If two stacks of shortwood are loaded side-by-side, in addition 
to meeting the requirements of paragraphs (d)(1) through (d)(5) of this 
section, they must be loaded so that:
    (i) There is no space between the two stacks of logs;
    (ii) The outside of each stack is raised at least 2.5 cm (1 in) 
within 10 cm (4 in) of the end of the logs or the side of the vehicle;
    (iii) The highest log is no more than 2.44 m (8 ft) above the deck; 
and
    (iv) At least one tiedown is used lengthwise across each stack of 
logs.
    (e) Securement of logs loaded lengthwise on flatbed and frame 
vehicles. In addition to meeting the requirements of paragraphs (b) and 
(c) of this section, each stack of shortwood loaded lengthwise on a 
frame vehicle or on a flatbed must be secured to the vehicle by at least 
two tiedowns.
    (f) Securement of logs transported on pole trailers. (1) The load 
must be secured by at least one tiedown at each bunk, or alternatively, 
by at least two tiedowns used as wrappers that encircle the entire load 
at locations along the load that provide effective securement.
    (2) The front and rear wrappers must be at least 3.04 meters (10 
feet) apart.
    (3) Large diameter single and double log loads must be immobilized 
with chock blocks or other equivalent means to prevent shifting.
    (4) Large diameter logs that rise above bunks must be secured to the 
underlying load with at least two additional wrappers.

Sec. 393.118  What are the rules for securing dressed lumber or similar 
          building products?

    (a) Applicability. The rules in this section apply to the 
transportation of bundles of dressed lumber, packaged lumber, building 
products such as plywood, gypsum board or other materials of similar 
shape. Lumber or building products which are not bundled or packaged 
must be treated as loose items and transported in accordance with 
Sec. Sec. 393.100 through 393.114 of this subpart. For the purpose of 
this section, ``bundle'' refers to packages of lumber, building 
materials or similar products which are unitized for securement as a 
single article of cargo.
    (b) Positioning of bundles. Bundles must be placed side by side in 
direct contact with each other, or a means must be provided to prevent 
bundles from shifting towards each other.
    (c) Securement of bundles transported using no more than one tier. 
Bundles carried on one tier must be secured in accordance with the 
general provisions of Sec. Sec. 393.100 through 393.114.
    (d) Securement of bundles transported using more than one tier. 
Bundles carried in more than one tier must be either:
    (1) Blocked against lateral movement by stakes on the sides of the 
vehicle and secured by tiedowns laid out over

[[Page 439]]

the top tier, as outlined in the general provisions of Sec. Sec. 
393.100 through 393.114; or
    (2) Restrained from lateral movement by blocking or high friction 
devices between tiers and secured by tiedowns laid out over the top 
tier, as outlined in the general provisions of Sec. Sec. 393.100 
through 393.114; or
    (3) Placed directly on top of other bundles or on spacers and 
secured in accordance with the following:
    (i) The length of spacers between bundles must provide support to 
all pieces in the bottom row of the bundle.
    (ii) The width of individual spacers must be equal to or greater 
than the height.
    (iii) If spacers are comprised of layers of material, the layers 
must be unitized or fastened together in a manner which ensures that the 
spacer performs as a single piece of material.
    (iv) The arrangement of the tiedowns for the bundles must be:
    (A) Secured by tiedowns over the top tier of bundles, in accordance 
with the general provisions of Sec. Sec. 393.100 through 393.114 with a 
minimum of two tiedowns for bundles longer than 1.52 meters (5 ft); and
    (B) Secured by tiedowns in accordance with the general provisions of 
Sec. Sec. 393.100 through 393.114 over the second tier or over a middle 
tier of a maximum height of 1.85 meters (6 ft) above the trailer deck, 
whichever is greater, for each stack of bundles composed of more than 
two tiers; or
    (4) Secured by tiedowns over each tier of bundles, in accordance 
with Sec. Sec. 393.100 through 393.114 using a minimum of two tiedowns 
over each of the top bundles longer than 1.52 meters (5 ft), in all 
circumstances.

Sec. 393.120  What are the rules for securing metal coils?

    (a) Applicability. The rules in this section apply to the 
transportation of one or more metal coils which, individually or grouped 
together, weigh 2268 kg (5000 pounds) or more. Shipments of metal coils 
that weigh less than 2268 kg (5000 pounds) may be secured in accordance 
with the provisions of Sec. Sec. 393.100 through 393.114.
    (b) Securement of coils transported with eyes vertical on a flatbed 
vehicle, in a sided vehicle or intermodal container with anchor points--
(1) An individual coil. Each coil must be secured by tiedowns arranged 
in a manner to prevent the coils from tipping in the forward, rearward, 
and lateral directions. The restraint system must include the following:
    (i) At least one tiedown attached diagonally from the left side of 
the vehicle or intermodal container (near the forwardmost part of the 
coil), across the eye of the coil, to the right side of the vehicle or 
intermodal container (near the rearmost part of the coil);
    (ii) At least one tiedown attached diagonally from the right side of 
the vehicle or intermodal container (near the forwardmost part of the 
coil), across the eye of the coil, to the left side of the vehicle or 
intermodal container (near the rearmost part of the coil);
    (iii) At least one tiedown attached transversely over the eye of the 
coil; and
    (iv) Either blocking and bracing, friction mats or tiedowns must be 
used to prevent longitudinal movement in the forward direction.
    (2) Coils grouped in rows. When coils are grouped and loaded side by 
side in a transverse or longitudinal row, the each row of coils must be 
secured by the following:
    (i) At least one tiedown attached to the front of the row of coils, 
restraining against forward motion, and whenever practicable, making an 
angle no more than 45 degrees with the floor of the vehicle or 
intermodal container when viewed from the side of the vehicle or 
container;
    (ii) At least one tiedown attached to the rear of the row of coils, 
restraining against rearward motion, and whenever practicable, making an 
angle no more than 45 degrees with the floor of the vehicle or 
intermodal container when viewed from the side of the vehicle or 
container;
    (iii) At least one tiedown over the top of each coil or transverse 
row of coils, restraining against vertical motion. Tiedowns going over 
the top of a coil(s) must be as close as practicable to the eye of the 
coil and positioned to prevent the tiedown from slipping or becoming 
unintentionally unfastened while the vehicle is in transit; and

[[Page 440]]

    (iv) Tiedowns must be arranged to prevent shifting or tipping in the 
forward, rearward and lateral directions.
    (c) Securement of coils transported with eyes crosswise on a flatbed 
vehicle, in a sided vehicle or intermodal container with anchor points--
(1) An individual coil. Each coil must be secured by the following:
    (i) A means (e.g., timbers, chocks or wedges, a cradle, etc.) to 
prevent the coil from rolling. The means of preventing rolling must 
support the coil off the deck, and must not be capable of becoming 
unintentionally unfastened or loose while the vehicle is in transit. If 
timbers, chocks or wedges are used, they must be held in place by coil 
bunks or similar devices to prevent them from coming loose. The use of 
nailed blocking or cleats as the sole means to secure timbers, chocks or 
wedges, or a nailed wood cradle, is prohibited;
    (ii) At least one tiedown through its eye, restricting against 
forward motion, and whenever practicable, making an angle no more than 
45 degrees with the floor of the vehicle or intermodal container when 
viewed from the side of the vehicle or container; and
    (iii) At least one tiedown through its eye, restricting against 
rearward motion, and whenever practicable, making an angle no more than 
45 degrees with the floor of the vehicle or intermodal container when 
viewed from the side of the vehicle or container.
    (2) Prohibition on crossing of tiedowns when coils are transported 
with eyes crosswise. Attaching tiedowns diagonally through the eye of a 
coil to form an X-pattern when viewed from above the vehicle is 
prohibited.
    (d) Securement of coils transported with eyes lengthwise on a 
flatbed vehicle, in a sided vehicle or intermodal container with anchor 
points--(1) An individual coil-option 1. Each coil must be secured by:
    (i) A means (e.g., timbers, chocks or wedges, a cradle, etc.) to 
prevent the coil from rolling. The means of preventing rolling must 
support the coil off the deck, and must not be capable of becoming 
unintentionally unfastened or loose while the vehicle is in transit. If 
timbers, chocks or wedges are used, they must be held in place by coil 
bunks or similar devices to prevent them from coming loose. The use of 
nailed blocking or cleats as the sole means to secure timbers, chocks or 
wedges, or a nailed wood cradle, is prohibited;
    (ii) At least one tiedown attached diagonally through its eye from 
the left side of the vehicle or intermodal container (near the forward-
most part of the coil), to the right side of the vehicle or intermodal 
container (near the rearmost part of the coil), making an angle no more 
than 45 degrees, whenever practicable, with the floor of the vehicle or 
intermodal container when viewed from the side of the vehicle or 
container;
    (iii) At least one tiedown attached diagonally through its eye, from 
the right side of the vehicle or intermodal container (near the forward-
most part of the coil), to the left side of the vehicle or intermodal 
container (near the rearmost part of the coil), making an angle no more 
than 45 degrees, whenever practicable, with the floor of the vehicle or 
intermodal container when viewed from the side of the vehicle or 
container;
    (iv) At least one tiedown attached transversely over the top of the 
coil; and
    (v) Either blocking, or friction mats to prevent longitudinal 
movement.
    (2) An individual coil--option 2. Each coil must be secured by:
    (i) A means (e.g., timbers, chocks or wedges, a cradle, etc.) to 
prevent the coil from rolling. The means of preventing rolling must 
support the coil off the deck, and must not be capable of becoming 
unintentionally unfastened or loose while the vehicle is in transit. If 
timbers, chocks or wedges are used, they must be held in place by coil 
bunks or similar devices to prevent them from coming loose. The use of 
nailed blocking or cleats as the sole means to secure timbers, chocks or 
wedges, or a nailed wood cradle, is prohibited;
    (ii) At least one tiedown attached straight through its eye from the 
left side of the vehicle or intermodal container (near the forward-most 
part of the coil), to the left side of the vehicle or intermodal 
container (near the rearmost part of the coil), and, whenever 
practicable, making an angle no more

[[Page 441]]

than 45 degrees with the floor of the vehicle or intermodal container 
when viewed from the side of the vehicle or container;
    (iii) At least one tiedown attached straight through its eye, from 
the right side of the vehicle or intermodal container (near the forward-
most part of the coil), to the right side of the vehicle or intermodal 
container (near the rearmost part of the coil), and whenever 
practicable, making an angle no more than 45 degrees with the floor of 
the vehicle or intermodal container when viewed from the side of the 
vehicle or container;
    (iv) At least one tiedown attached transversely over the top of the 
coil; and
    (v) Either blocking or friction mats to prevent longitudinal 
movement.
    (3) An individual coil--option 3. Each coil must be secured by:
    (i) A means (e.g., timbers, chocks or wedges, a cradle, etc.) to 
prevent the coil from rolling. The means of preventing rolling must 
support the coil off the deck, and must not be capable of becoming 
unintentionally unfastened or loose while the vehicle is in transit. If 
timbers, chocks or wedges are used, they must be held in place by coil 
bunks or similar devices to prevent them from coming loose. The use of 
nailed blocking or cleats as the sole means to secure timbers, chocks or 
wedges, or a nailed wood cradle, is prohibited;
    (ii) At least one tiedown over the top of the coil, located near the 
forward-most part of the coil;
    (iii) At least one tiedown over the top of the coil located near the 
rearmost part of the coil; and
    (iv) Either blocking or friction mats to prevent longitudinal 
movement.he forward direction.
    (4) Rows of coils. Each transverse row of coils having approximately 
equal outside diameters must be secured with:
    (i) A means (e.g., timbers, chocks or wedges, a cradle, etc.) to 
prevent each coil in the row of coils from rolling. The means of 
preventing rolling must support each coil off the deck, and must not be 
capable of becoming unintentionally unfastened or loose while the 
vehicle is in transit. If timbers, chocks or wedges are used, they must 
be held in place by coil bunks or similar devices to prevent them from 
coming loose. The use of nailed blocking or cleats as the sole means to 
secure timbers, chocks or wedges, or a nailed wood cradle, is 
prohibited;
    (ii) At least one tiedown over the top of each coil or transverse 
row, located near the forward-most part of the coil;
    (iii) At least one tiedown over the top of each coil or transverse 
row, located near the rearmost part of the coil; and
    (iv) Either blocking, bracing or friction mats to prevent 
longitudinal movement.
    (e) Securement of coils transported in a sided vehicle without 
anchor points or an intermodal container without anchor points. Metal 
coils transported in a vehicle with sides without anchor points or an 
intermodal container without anchor points must be loaded in a manner to 
prevent shifting and tipping. The coils may also be secured using a 
system of blocking and bracing, friction mats, tiedowns, or a 
combination of these to prevent any horizontal movement and tipping.

Sec. 393.122  What are the rules for securing paper rolls?

    (a) Applicability. The rules in this section apply to shipments of 
paper rolls which, individually or together, weigh 2268 kg (5000 lb) or 
more. Shipments of paper rolls that weigh less than 2268 kg (5000 lb), 
and paper rolls that are unitized on a pallet, may either be secured in 
accordance with the rules in this section or the requirements of 
Sec. Sec. 393.100 through 393.114.
    (b) Securement of paper rolls transported with eyes vertical in a 
sided vehicle. (1) Paper rolls must be placed tightly against the walls 
of the vehicle, other paper rolls, or other cargo, to prevent movement 
during transit.
    (2) If there are not enough paper rolls in the shipment to reach the 
walls of the vehicle, lateral movement must be prevented by filling the 
void, blocking, bracing, tiedowns or friction mats. The paper rolls may 
also be banded together.
    (3) When any void behind a group of paper rolls, including that at 
the rear of the vehicle, exceeds the diameter of the paper rolls, 
rearward movement

[[Page 442]]

must be prevented by friction mats, blocking, bracing, tiedowns, or 
banding to other rolls.
    (4)(i) If a paper roll is not prevented from tipping or falling 
sideways or rearwards by vehicle structure or other cargo, and its width 
is more than 2 times its diameter, it must be prevented from tipping or 
falling by banding it to other rolls, bracing, or tiedowns.
    (ii) If the forwardmost roll(s) in a group of paper rolls is not 
prevented from tipping or falling forwards by vehicle structure or other 
cargo and it is restrained against forward movement by friction mat(s) 
alone, and its width is more than 1.75 times its diameter, it must be 
prevented from tipping or falling forwards by banding it to other rolls, 
bracing, or tiedowns.
    (iii) Otherwise, when a paper roll or the forwardmost roll in groups 
of rolls that are not prevented from tipping or falling forwards by 
vehicle structure or other cargo and its width exceeds 1.25 times its 
diameter it must be prevented from tipping or falling by banding it to 
other rolls, bracing or tiedowns.
    (5) If paper rolls are banded together, the rolls must be placed 
tightly against each other to form a stable group. The bands must be 
applied tightly, and must be secured so that they cannot fall off the 
rolls or to the deck.
    (6) A friction mat used to provide the principal securement for a 
paper roll must protrude from beneath the roll in the direction in which 
it is providing that securement.
    (c) Securement of split loads of paper rolls transported with eyes 
vertical in a sided vehicle. (1) If a paper roll in a split load is not 
prevented from forward movement by vehicle structure or other cargo, it 
must be prevented from forward movement by filling the open space, or by 
blocking, bracing, tiedowns, friction mats, or some combination of 
these.
    (2) A friction mat used to provide the principal securement for a 
paper roll must protrude from beneath the roll in the direction in which 
it is providing that securement.
    (d) Securement of stacked loads of paper rolls transported with eyes 
vertical in a sided vehicle. (1) Paper rolls must not be loaded on a 
layer of paper rolls beneath unless the lower layer extends to the front 
of the vehicle.
    (2) Paper rolls in the second and subsequent layers must be 
prevented from forward, rearward or lateral movement by means as allowed 
for the bottom layer, or by use of a blocking roll from a lower layer.
    (3) The blocking roll must be at least 38 mm (1.5 in) taller than 
other rolls, or must be raised at least 38 mm (1.5 in) using dunnage.
    (4) A roll in the rearmost row of any layer must not be raised using 
dunnage.
    (e) Securement of paper rolls transported with eyes crosswise in a 
sided vehicle. (1) The paper rolls must be prevented from rolling or 
shifting longitudinally by contact with vehicle structure or other 
cargo, by chocks, wedges or blocking and bracing of adequate size, or by 
tiedowns.
    (2) Chocks, wedges or blocking must be held securely in place by 
some means in addition to friction, so they cannot become 
unintentionally unfastened or loose while the vehicle is in transit.
    (3) The rearmost roll must not be secured using the rear doors of 
the vehicle or intermodal container, or by blocking held in place by 
those doors.
    (4) If there is more than a total of 203 mm (8 in) of space between 
the ends of a paper roll, or a row of rolls, and the walls of the 
vehicle, void fillers, blocking, bracing, friction mats, or tiedowns 
must be used to prevent the roll from shifting towards either wall.
    (f) Securement of stacked loads of paper rolls transported with eyes 
crosswise in a sided vehicle. (1) Rolls must not be loaded in a second 
layer unless the bottom layer extends to the front of the vehicle.
    (2) Rolls must not be loaded in a third or higher layer unless all 
wells in the layer beneath are filled.
    (3) The foremost roll in each upper layer, or any roll with an empty 
well in front of it, must be secured against forward movement by:
    (i) Banding it to other rolls, or
    (ii) Blocking against an adequately secured eye-vertical blocking 
roll resting on the floor of the vehicle which is

[[Page 443]]

at least 1.5 times taller than the diameter of the roll being blocked, 
or
    (iii) Placing it in a well formed by two rolls on the lower row 
whose diameter is equal to or greater than that of the roll on the upper 
row.
    (4) The rearmost roll in each upper layer must be secured by banding 
it to other rolls if it is located in either of the last two wells 
formed by the rearmost rolls in the layer below.
    (5) Rolls must be secured against lateral movement by the same means 
allowed for the bottom layer when there is more than a total of 203 mm 
(8 in) of space between the ends of a paper roll, or a row of rolls, and 
the walls of the vehicle.
    (g) Securement of paper rolls transported with the eyes lengthwise 
in a sided vehicle.
    (1) Each roll must be prevented from forward movement by contact 
with vehicle structure, other cargo, blocking or tiedowns.
    (2) Each roll must be prevented from rearward movement by contact 
with other cargo, blocking, friction mats or tiedowns.
    (3) The paper rolls must be prevented from rolling or shifting 
laterally by contact with the wall of the vehicle or other cargo, or by 
chocks, wedges or blocking of adequate size.
    (4) Chocks, wedges or blocking must be held securely in place by 
some means in addition to friction, so they cannot become 
unintentionally unfastened or loose while the vehicle is in transit.
    (h) Securement of stacked loads of paper rolls transported with the 
eyes lengthwise in a sided vehicle. (1) Rolls must not be loaded in a 
higher layer if another roll will fit in the layer beneath.
    (2) An upper layer must be formed by placing paper rolls in the 
wells formed by the rolls beneath.
    (3) A roll in an upper layer must be secured against forward and 
rearward movement by any of the means allowed for the bottom layer, by 
use of a blocking roll, or by banding to other rolls.
    (i) Securement of paper rolls transported on a flatbed vehicle or in 
a curtain-sided vehicle--(1) Paper rolls with eyes vertical or with eyes 
lengthwise.
    (i) The paper rolls must be loaded and secured as described for a 
sided vehicle, and the entire load must be secured by tiedowns in 
accordance with the requirements of Sec. Sec. 393.100 through 393.114.
    (ii) Stacked loads of paper rolls with eyes vertical are prohibited.
    (2) Paper rolls with eyes crosswise. (i) The paper rolls must be 
prevented from rolling or shifting longitudinally by contact with 
vehicle structure or other cargo, by chocks, wedges or blocking and 
bracing of adequate size, or by tiedowns.
    (ii) Chocks, wedges or blocking must be held securely in place by 
some means in addition to friction so that they cannot become 
unintentionally unfastened or loose while the vehicle is in transit.
    (iii) Tiedowns must be used in accordance with the requirements of 
Sec. Sec. 393.100 through 393.114 to prevent lateral movement.

Sec. 393.124  What are the rules for securing concrete pipe?

    (a) Applicability. (1) The rules in this section apply to the 
transportation of concrete pipe on flatbed trailers and vehicles, and 
lowboy trailers.
    (2) Concrete pipe bundled tightly together into a single rigid 
article that has no tendency to roll, and concrete pipe loaded in a 
sided vehicle or container must be secured in accordance with the 
provisions of Sec. Sec. Sec. 393.100 through 393.114.
    (b) General specifications for tiedowns. (1) The aggregate working 
load limit of all tiedowns on any group of pipes must not be less than 
half the total weight of all the pipes in the group.
    (2) A transverse tiedown through a pipe on an upper tier or over 
longitudinal tiedowns is considered to secure all those pipes beneath on 
which that tiedown causes pressure.
    (c) Blocking. (1) Blocking may be one or more pieces placed 
symmetrically about the center of a pipe.
    (2) One piece must extend at least half the distance from the center 
to each end of the pipe, and two pieces must be placed on the opposite 
side, one at each end of the pipe.
    (3) Blocking must be placed firmly against the pipe, and must be 
secured

[[Page 444]]

to prevent it moving out from under the pipe.
    (4) Timber blocking must have minimum dimensions of at least 10 x 15 
cm (4 x 6 in).
    (d) Arranging the load--(1) Pipe of different diameter. If pipe of 
more than one diameter are loaded on a vehicle, groups must be formed 
that consist of pipe of only one size, and each group must be separately 
secured.
    (2) Arranging a bottom tier. The bottom tier must be arranged to 
cover the full length of the vehicle, or as a partial tier in one group 
or two groups.
    (3) Arranging an upper tier. Pipe must be placed only in the wells 
formed by adjacent pipes in the tier beneath. A third or higher tier 
must not be started unless all wells in the tier beneath are filled.
    (4) Arranging the top tier. The top tier must be arranged as a 
complete tier, a partial tier in one group, or a partial tier in two 
groups.
    (5) Arranging bell pipe. (i) Bell pipe must be loaded on at least 
two longitudinal spacers of sufficient height to ensure that the bell is 
clear of the deck.
    (ii) Bell pipe loaded in one tier must have the bells alternating on 
opposite sides of the vehicle.
    (iii) The ends of consecutive pipe must be staggered, if possible, 
within the allowable width, otherwise they must be aligned.
    (iv) Bell pipe loaded in more than one tier must have the bells of 
the bottom tier all on the same side of the vehicle.
    (v) Pipe in every upper tier must be loaded with bells on the 
opposite side of the vehicle to the bells of the tier below.
    (vi) If the second tier is not complete, pipe in the bottom tier 
which do not support a pipe above must have their bells alternating on 
opposite sides of the vehicle.
    (a) Securing pipe with an inside diameter up to 1,143 mm (45 in). In 
addition to the requirements of paragraphs (b), (c) and (d) of this 
section, the following rules must be satisfied:
    (1) Stabilizing the bottom tier. (i) The bottom tier must be 
immobilized longitudinally at each end by blocking, vehicle end 
structure, stakes, a locked pipe unloader, or other equivalent means.
    (ii) Other pipe in the bottom tier may also be held in place by 
blocks and/or wedges; and
    (iii) Every pipe in the bottom tier must also be held firmly in 
contact with the adjacent pipe by tiedowns though the front and rear 
pipes:
    (A) At least one tiedown through the front pipe of the bottom tier 
must run aft at an angle not more than 45 degrees with the horizontal, 
whenever practicable.
    (B) At least one tiedown through the rear pipe of the bottom tier 
must run forward at an angle not more than 45 degrees with the 
horizontal, whenever practicable.
    (2) Use of tiedowns. (i) Each pipe may be secured individually with 
tiedowns through the pipe.
    (ii) If each pipe is not secured individually with a tiedown, then:
    (A) Either one 1/2-inch diameter chain or wire rope, or two 3/8-inch 
diameter chain or wire rope, must be placed longitudinally over the 
group of pipes;
    (B) One transverse tiedown must be used for every 3.04 m (10 ft) of 
load length. The transverse tiedowns may be placed through a pipe, or 
over both longitudinal tiedowns between two pipes on the top tier.
    (C) If the first pipe of a group in the top tier is not placed in 
the first well formed by pipes at the front of the tier beneath, it must 
be secured by an additional tiedown that runs rearward at an angle not 
more than 45 degrees to the horizontal, whenever practicable. This 
tiedown must pass either through the front pipe of the upper tier, or 
outside it and over both longitudinal tiedowns; and
    (D) If the last pipe of a group in the top tier is not placed in the 
last well formed by pipes at the rear of the tier beneath, it must be 
secured by an additional tiedown that runs forward at an angle not more 
than 45 degrees to the horizontal, whenever practicable. This tiedown 
must pass either through the rear pipe of the upper tier or outside it 
and over both longitudinal tiedowns.
    (f) Securing large pipe, with an inside diameter over 1143 mm (45 
in). In addition to the requirements of paragraphs (b), (c) and (d) of 
this section, the following rules must be satisfied:

[[Page 445]]

    (1) The front pipe and the rear pipe must be immobilized by 
blocking, wedges, vehicle end structure, stakes, locked pipe unloader, 
or other equivalent means.
    (2) Each pipe must be secured by tiedowns through the pipe:
    (i) At least one tiedown through each pipe in the front half of the 
load, which includes the middle one if there is an odd number, and must 
run rearward at an angle not more than 45 degrees with the horizontal, 
whenever practicable.
    (ii) At least one tiedown through each pipe in the rear half of the 
load, and must run forward at an angle not more than 45 degrees with the 
horizontal, whenever practicable, to hold each pipe firmly in contact 
with adjacent pipe; and
    (iii) If the front or rear pipe is not also in contact with vehicle 
end structure, stakes, a locked pipe unloader, or other equivalent 
means, at least two tiedowns positioned as described in paragraphs 
(f)(2)(i) and (ii) of this section, must be used through that pipe.
    (3) If only one pipe is transported, or if several pipes are 
transported without contact between other pipes, the requirements in 
this paragraph apply to each pipe as a single front and rear article.

Sec. 393.126  What are the rules for securing intermodal containers?

    (a) Applicability. The rules in this section apply to the 
transportation of intermodal containers. Cargo contained within an 
intermodal container must be secured in accordance with the provisions 
of Sec. Sec. 393.100 through 393.114 or, if applicable, the commodity 
specific rules of this part.
    (b) Securement of intermodal containers transported on container 
chassis vehicle(s). (1) Each intermodal container must be secured to the 
container chassis with securement devices or integral locking devices 
that cannot unintentionally become unfastened while the vehicle is in 
transit.
    (2) The securement devices must restrain the container from moving 
more than 1.27 cm (1/2 in) forward, more than 1.27 cm (1/2 in) aft, more 
than 1.27 cm (1/2 in) to the right, more than 1.27 cm (1/2 in) to the 
left, or more than 2.54 cm (1 in) vertically.
    (3) The front and rear of the container must be secured 
independently.
    (c) Securement of loaded intermodal containers transported on 
vehicles other than container chassis vehicle(s). (1) All lower corners 
of the intermodal container must rest upon the vehicle, or the corners 
must be supported by a structure capable of bearing the weight of the 
container and that support structure must be independently secured to 
the motor vehicle.
    (2) Each container must be secured to the vehicle by:
    (i) Chains, wire ropes or integral devices which are fixed to all 
lower corners; or
    (ii) Crossed chains which are fixed to all upper corners; and,
    (3) The front and rear of the container must be secured 
independently. Each chain, wire rope, or integral locking device must be 
attached to the container in a manner that prevents it from being 
unintentionally unfastened while the vehicle is in transit.
    (d) Securement of empty intermodal containers transported on 
vehicles other than container chassis vehicle(s). Empty intermodal 
containers transported on vehicles other than container chassis vehicles 
do not have to have all lower corners of the intermodal container 
resting upon the vehicle, or have all lower corners supported by a 
structure capable of bearing the weight of the empty container, 
provided:
    (1) The empty intermodal container is balanced and positioned on the 
vehicle in a manner such that the container is stable before the 
addition of tiedowns or other securement equipment; and,
    (2) The amount of overhang for the empty container on the trailer 
does not exceed five feet on either the front or rear of the trailer;
    (3) The empty intermodal container must not interfere with the 
vehicle's maneuverability; and,
    (4) The empty intermodal container is secured to prevent lateral, 
longitudinal, or vertical shifting.

Sec. 393.128  What are the rules for securing automobiles, light trucks 
          and vans?

    (a) Applicability. The rules in this section apply to the 
transportation of

[[Page 446]]

automobiles, light trucks, and vans which individually weigh 4,536 kg. 
(10,000 lb) or less. Vehicles which individually are heavier than 4,536 
kg (10,000 lb) must be secured in accordance with the provisions of 
Sec. 393.130 of this part.
    (b) Securement of automobiles, light trucks, and vans.
    (1) Automobiles, light trucks, and vans must be restrained at both 
the front and rear to prevent lateral, forward, rearward, and vertical 
movement using a minimum of two tiedowns.
    (2) Tiedowns that are designed to be affixed to the structure of the 
automobile, light truck, or van must use the mounting points on those 
vehicles that have been specifically designed for that purpose.
    (3) Tiedowns that are designed to fit over or around the wheels of 
an automobile, light truck, or van must provide restraint in the 
lateral, longitudinal and vertical directions.
    (4) Edge protectors are not required for synthetic webbing at points 
where the webbing comes in contact with the tires.

Sec. 393.130  What are the rules for securing heavy vehicles, equipment 
          and machinery?

    (a) Applicability. The rules in this section apply to the 
transportation of heavy vehicles, equipment and machinery which operate 
on wheels or tracks, such as front end loaders, bulldozers, tractors, 
and power shovels and which individually weigh 4,536 kg (10,000 lb.) or 
more. Vehicles, equipment and machinery which is lighter than 4,536 kg 
(10,000 lb.) may also be secured in accordance with the provisions of 
this section, with Sec. 393.128, or in accordance with the provisions 
of Sec. Sec. 393.100 through 393.114.
    (b) Preparation of equipment being transported. (1) Accessory 
equipment, such as hydraulic shovels, must be completely lowered and 
secured to the vehicle.
    (2) Articulated vehicles shall be restrained in a manner that 
prevents articulation while in transit.
    (c) Securement of heavy vehicles, equipment or machinery with 
crawler tracks or wheels. (1) In addition to the requirements of 
paragraph (b) of this section, heavy equipment or machinery with crawler 
tracks or wheels must be restrained against movement in the lateral, 
forward, rearward, and vertical direction using a minimum of four 
tiedowns.
    (2) Each of the tiedowns must be affixed as close as practicable to 
the front and rear of the vehicle, or mounting points on the vehicle 
that have been specifically designed for that purpose.

Sec. 393.132  What are the rules for securing flattened or crushed 
          vehicles?

    (a) Applicability. The rules in this section apply to the 
transportation of vehicles such as automobiles, light trucks, and vans 
that have been flattened or crushed.
    (b) Prohibition on the use of synthetic webbing. The use of 
synthetic webbing to secure flattened or crushed vehicles is prohibited.
    (c) Securement of flattened or crushed vehicles. Flattened or 
crushed vehicles must be transported on vehicles which have:
    (1) Containment walls or comparable means on four sides which extend 
to the full height of the load and which block against movement of the 
cargo in the forward, rearward and lateral directions; or
    (2)(i) Containment walls or comparable means on three sides which 
extend to the full height of the load and which block against movement 
of the cargo in the forward, rearward and the lateral direction for 
which there is no containment wall or comparable means, and
    (ii) A minimum of two tiedowns are required per vehicle stack; or
    (3)(i) Containment walls on two sides which extend to the full 
height of the load and which block against movement of the cargo in the 
forward and rearward directions, and
    (ii) A minimum of three tiedowns are required per vehicle stack; or
    (4) A minimum of four tiedowns per vehicle stack.
    (5) In addition to the requirements of paragraphs (c)(2), (3), and 
(4), the following rules must be satisfied:
    (i) Vehicles used to transport flattened or crushed vehicles must be 
equipped with a means to prevent loose

[[Page 447]]

parts from falling from all four sides of the vehicle which extends to 
the full height of the cargo.
    (ii) The means used to contain loose parts may consist of structural 
walls, sides or sideboards, or suitable covering material, alone or in 
combinations.
    (iii) The use of synthetic material for containment of loose parts 
is permitted.

Sec. 393.134  What are the rules for securing roll-on/roll-off or hook 
          lift containers?

    (a) Applicability. The rules in this section apply to the 
transportation of roll-on/roll-off or hook lift containers.
    (b) Securement of a roll-on/roll-off and hook lift container. Each 
roll-on/roll-off and hook lift container carried on a vehicle which is 
not equipped with an integral securement system must be:
    (1) Blocked against forward movement by the lifting device, stops, a 
combination of both or other suitable restraint mechanism;
    (2) Secured to the front of the vehicle by the lifting device or 
other suitable restraint against lateral and vertical movement;
    (3) Secured to the rear of the vehicle with at least one of the 
following mechanisms:
    (i) One tiedown attached to both the vehicle chassis and the 
container chassis;
    (ii) Two tiedowns installed lengthwise, each securing one side of 
the container to one of the vehicle's side rails; or
    (iii) Two hooks, or an equivalent mechanism, securing both sides of 
the container to the vehicle chassis at least as effectively as the 
tiedowns in the two previous items.
    (4) The mechanisms used to secure the rear end of a roll-on/roll off 
or hook lift container must be installed no more than two meters (6 ft 7 
in) from the rear of the container.
    (5) In the event that one or more of the front stops or lifting 
devices are missing, damaged or not compatible, additional manually 
installed tiedowns must be used to secure the container to the vehicle, 
providing the same level of securement as the missing, damaged or 
incompatible components.

Sec. 393.136  What are the rules for securing large boulders?

    (a) Applicability. (1) The rules in this section are applicable to 
the transportation of any large piece of natural, irregularly shaped 
rock weighing in excess of 5,000 kg (11,000 lb.) or with a volume in 
excess of 2 cubic-meters on an open vehicle, or in a vehicle whose sides 
are not designed and rated to contain such cargo.
    (2) Pieces of rock weighing more than 100 kg (220 lb.), but less 
than 5,000 kg (11,000 lb.) must be secured, either in accordance with 
this section, or in accordance with the provisions of Sec. Sec. 393.100 
through 393.114, including:
    (i) Rock contained within a vehicle which is designed to carry such 
cargo; or
    (ii) Secured individually by tiedowns, provided each piece can be 
stabilized and adequately secured.
    (3) Rock which has been formed or cut to a shape and which provides 
a stable base for securement must also be secured, either in accordance 
with the provisions of this section, or in accordance with the 
provisions of Sec. Sec. 393.100 through 393.114.
    (b) General requirements for the positioning of boulders on the 
vehicle. (1) Each boulder must be placed with its flattest and/or 
largest side down.
    (2) Each boulder must be supported on at least two pieces of hard 
wood blocking at least 10 cm x 10 cm (4 inches x 4 inches) side 
dimensions extending the full width of the boulder.
    (3) Hardwood blocking pieces must be placed as symmetrically as 
possible under the boulder and should support at least three-fourths of 
the length of the boulder.
    (4) If the flattest side of a boulder is rounded or partially 
rounded, so that the boulder may roll, it must be placed in a crib made 
of hardwood timber fixed to the deck of the vehicle so that the boulder 
rests on both the deck and the timber, with at least three well-
separated points of contact that prevent its tendency to roll in any 
direction.
    (5) If a boulder is tapered, the narrowest end must point towards 
the front of the vehicle.

[[Page 448]]

    (c) General tiedown requirements. (1) Only chain may be used as 
tiedowns to secure large boulders.
    (2) Tiedowns which are in direct contact with the boulder should, 
where possible, be located in valleys or notches across the top of the 
boulder, and must be arranged to prevent sliding across the rock 
surface.
    (d) Securement of a cubic shaped boulder. In addition to the 
requirements of paragraphs (b) and (c) of this section, the following 
rules must be satisfied:
    (1) Each boulder must be secured individually with at least two 
chain tiedowns placed transversely across the vehicle.
    (2) The aggregate working load limit of the tiedowns must be at 
least half the weight of the boulder.
    (3) The tiedowns must be placed as closely as possible to the wood 
blocking used to support the boulder.
    (e) Securement of a non-cubic shaped boulder--with a stable base. In 
addition to the requirements of paragraphs (b) and (c) of this section, 
the following rules must be satisfied:
    (1) The boulder must be secured individually with at least two chain 
tiedowns forming an ``X'' pattern over the boulder.
    (2) The aggregate working load limit of the tiedowns must be at 
least half the weight of the boulder.
    (3) The tiedowns must pass over the center of the boulder and must 
be attached to each other at the intersection by a shackle or other 
connecting device.
    (f) Securement of a non-cubic shaped boulder--with an unstable base. 
In addition to the requirements of paragraphs (b) and (c) of this 
section, each boulder must be secured by a combination of chain tiedowns 
as follows:
    (1) One chain must surround the top of the boulder (at a point 
between one-half and two-thirds of its height). The working load limit 
of the chain must be at least half the weight of the boulder.
    (2) Four chains must be attached to the surrounding chain and the 
vehicle to form a blocking mechanism which prevents any horizontal 
movement. Each chain must have a working load limit of at least one-
fourth the weight of the boulder. Whenever practicable, the angle of the 
chains must not exceed 45 degrees from the horizontal.

    Subpart J_Frames, Cab and Body Components, Wheels, Steering, and 
                           Suspension Systems

    Source: 53 FR 49402, Dec. 7, 1988, unless otherwise noted.

Sec. 393.201  Frames.

    (a) The frame or chassis of each commercial motor vehicle shall not 
be cracked, loose, sagging or broken.
    (b) Bolts or brackets securing the cab or the body of the vehicle to 
the frame must not be loose, broken, or missing.
    (c) The frame rail flanges between the axles shall not be bent, cut 
or notched, except as specified by the manufacturer.
    (d) Parts and accessories shall not be welded to the frame or 
chassis of a commercial motor vehicle except in accordance with the 
vehicle manufacturer's recommendations. Any welded repair of the frame 
must also be in accordance with the vehicle manufacturer's 
recommendations.
    (e) No holes shall be drilled in the top or bottom rail flanges, 
except as specified by the manufacturer.

[53 FR 49402, Dec. 7, 1988, as amended at 70 FR 48055, Aug. 15, 2005]

Sec. 393.203  Cab and body components.

    (a) The cab compartment doors or door parts used as an entrance or 
exist shall not be missing or broken. Doors shall not sag so that they 
cannot be properly opened or closed. No door shall be wired shut or 
otherwise secured in the closed position so that it cannot be readily 
opened. Exception: When the vehicle is loaded with pipe or bar stock 
that blocks the door and the cab has a roof exit.
    (b) Bolts or brackets securing the cab or the body of the vehicle to 
the frame shall not be loose, broken, or missing.
    (c) The hood must be securely fastened.
    (d) All seats must be securely mounted.
    (e) The front bumper must not be missing, loosely attached, or 
protruding beyond the confines of the vehicle so as to create a hazard.

[[Page 449]]

Sec. 393.205  Wheels.

    (a) Wheels and rims shall not be cracked or broken.
    (b) Stud or bolt holes on the wheels shall shall not be elongated 
(out of round).
    (c) Nuts or bolts shall not be missing or loose.

Sec. 393.207  Suspension systems.

    (a) Axles. No axle positioning part shall be cracked, broken, loose 
or missing. All axles must be in proper alignment.
    (b) Adjustable axles. Adjustable axle assemblies shall not have 
locking pins missing or disengaged.
    (c) Leaf springs. No leaf spring shall be cracked, broken, or 
missing nor shifted out of position.
    (d) Coil springs. No coil spring shall be cracked or broken.
    (e) Torsion bar. No torsion bar or torsion bar suspension shall be 
cracked or broken.
    (f) Air suspensions. The air pressure regulator valve shall not 
allow air into the suspension system until at least 55 psi is in the 
braking system. The vehicle shall be level (not tilting to the left or 
right). Air leakage shall not be greater than 3 psi in a 5-minute time 
period when the vehicle's air pressure gauge shows normal operating 
pressure.
    (g) Air suspension exhaust controls. The air suspension exhaust 
controls must not have the capability to exhaust air from the suspension 
system of one axle of a two-axle air suspension trailer unless the 
controls are either located on the trailer, or the power unit and 
trailer combination are not capable of traveling at a speed greater than 
10 miles per hour while the air is exhausted from the suspension system. 
This paragraph shall not be construed to prohibit--
    (1) Devices that could exhaust air from both axle systems 
simultaneously; or
    (2) Lift axles on multi-axle units.

[53 FR 49402, Dec. 7, 1988, as amended at 70 FR 48055, Aug. 15, 2005]

Sec. 393.209  Steering wheel systems.

    (a) The steering wheel shall be secured and must not have any spokes 
cracked through or missing.
    (b) Steering wheel lash. (1) The steering wheel lash shall not 
exceed the following parameters:

------------------------------------------------------------------------
                                 Manual steering       Power steering
   Steering wheel diameter           system                system
------------------------------------------------------------------------
406 mm or less (16 inches or  51 mm (2 inches)....  108 mm (4\1/4\
 less).                                              inches).
457 mm (18 inches)..........  57 mm (2\1/4\         121 mm (4\3/4\
                               inches).              inches).
483 mm (19 inches)..........  60 mm (2\3/8\         127 mm (5 inches).
                               inches).
508 mm (20 inches)..........  64 mm (2\1/2\         133 mm (5\1/4\
                               inches).              inches).
533 mm (21 inches)..........  67 mm (2\5/8\         140 mm (5\1/2\
                               inches).              inches).
559 mm (22 inches)..........  70 mm (2\3/4\         146 mm (5\3/4\
                               inches).              inches).
------------------------------------------------------------------------

    (2) For steering wheel diameters not listed in paragraph (b)(1) of 
this section the steering wheel lash shall not exceed 14 degrees angular 
rotation for manual steering systems, and 30 degrees angular rotation 
for power steering systems.
    (c) Steering column. The steering column must be securely fastened.
    (d) Steering system. Universal joints and ball-and-socket joints 
shall not be worn, faulty or repaired by welding. The steering gear box 
shall not have loose or missing mounting bolts or cracks in the gear box 
or mounting brackets. The pitman arm on the steering gear output shaft 
shall not be loose. Steering wheels shall turn freely through the limit 
of travel in both directions.
    (e) Power steering systems. All components of the power system must 
be in operating condition. No parts shall be loose or broken. Belts 
shall not be frayed, cracked or slipping. The system shall not leak. The 
power steering system shall have sufficient fluid in the reservoir.

[53 FR 49402, Dec. 7, 1988, as amended at 70 FR 48055, Aug. 15, 2005]

                           PART 394 [RESERVED]

[[Page 450]]