Investigation Guideline

Investigation Guideline
Product: Snow Throwers
Appendix #: 71
Date amended: September 2004
I. Introduction
A. Background Information
Snow throwers may be a luxury or a necessity depending upon geography and individual
circumstances, but many of the injuries sustained while using machines were relatively serious
compared to other outdoor powered equipment. Clogging of the discharge chute with wet and heavy
snow and failure to shut the engine off while attempting to clear the discharge chute are the major
hazard associated with snow throwers.
Research indicated that when hand skin temperatures are below 60o F there is a predictable
deterioration in hand function. Exposure to cold temperatures over time can result in decreased manual
dexterity, increased reaction time, and decreased sensitivity. Human performance is also degraded by
exposure to the noise and vibration associated with snow thrower operation.

B. Product Descriptions
Both self-contained, walk-behind snow throwers and attachment snow throwers are classified into
two types: (1) a single-stage snow thrower that cuts into the snow and simultaneously ejects it through
the discharge chute by a single blade (auger) which combines the collecting and impelling functions and
(2) a two -stage snow thrower that collects snow (by an auger) which is accelerated through the
discharge chute by a separate, second set of smaller impeller blades. In general, most single-stage snow
thrower engines range from 2.5 to 6.0 horsepower; some are greater. The two-stage machines generally
have larger engines with 4 or more horsepower. Attachment snow throwers are attached to lawn
tractors and are operated through the PTO (Powered Take Off) of the lawn tractor.

C. Specific Items of Interest
The product of particular interest to the Commission is walk-behind snow throwers. They can be
gasoline or electric-powered, pushed (manually) or self-propelled (powered), and single-stage or twostage operation.
In single-stage operation, the snow is collected and thrown through a discharge chute by a single
device which combines the collecting and impelling functions. This device can be correctly identified
as collector/impeller, an auger/impeller, or according to ANSI B71.3, an impeller (See Figure 1).
In a two-stage operation, the collector and impeller functions are separate. Snow is collected by an
auger-like device after which it is accelerated through the discharge chute by a separate impeller fan.
The impeller can be independently powered (See Figure 2).

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Figure 1: Single-Stage

Figure 2: Dual-Stage

D. Headquarters Contacts
Natalie Marcy, EHHA (301)504-7329
John Murphy, ESME (301)504-7541

II. Instructions for Collecting Specific Information
A. Synopsis
A complete description of the conditions under which the snow thrower was being used is
necessary to determine the cause of the injury. Of special concern to the Commission are injuries which
occur when the operator places his/her hand into the discharge chute when the impeller has stopped, and
by releasing packed snow/ice allows the impeller blade to “spring back” or “recoil”, trapping the
operator’s hand.
When product-related factors, environmental factors, and human factors are all likely to be
involved, it is important to establish a clear sequence of events when investigating the accident.
Accidents can involve the operator, or bystander, or both. The investigator is not limited to the topics
below. Each topic can be approached in an open-ended fashion.
Note: For data retrieval from the computer, please make sure that the following key words are used in
the synopsis as appropriate: walk-behind, riding, gasoline, electric, impeller, auger, collector, recoil,
deadman, hand, single-stage, two-stage, blade.

B. Description of Incident Environment
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Indicate weather conditions at the time of the accident (windy, snow, clear, etc.).
Indicate air temperature, wind, wind chill index. (contact with weather service may be
required)
Indicate lighting conditions at the time of the accident.
Indicate time of day.
Indicate surface being cleared of snow (gravel driveway, concrete, etc.), presence of debris.
Indicated amount (in inches/feet) and type (wet, dry and powdery) of snow.
Indicated presence of ice on ground.
Indicate ground conditions (slippery, wet, muddy, icy, slushy).
Specify degree of slope if machine was used on an incline.

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o
o

Indicate if salt was used on snow prior to removal.
Indicate if noise from snow thrower, or other source, was distracting or disorienting to
operator.

C. Description of Interaction between Injured Person(s) and Product
o

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Operator/Victim description:
o Height, weight, age
o Body build (e.g., small or slight, medium, large or heavy set)
o Competence reduction factors (e.g., impaired vision, medication, physical
disabilities, etc.)
o Experience with and knowledge of product performance.
o Familiarity with snow thrower operating instructions and warnings (operator’s
manual)
o Victim’s clothing at the time of the accident, indicating type, materials, loose or
snug fit, use of gloves or mittens, type of footwear and sole (slip-resistant) and
degree of protection or contribution to the accident because of entanglement in
the snow thrower.
Indicate the operating status of the snow thrower (i.e., engine running and impeller engaged;
engine shut off and impeller disengaged, etc.)
Indicate whether the victim was cleaning the discharge chute of snow/ice; specify hand
positioning, protection (gloves, type and material), and use of implement (stick, etc.).
Indicate whether the victim’s vision was blocked while cleaning the discharge chute (handeye coordination).
Indicate the amount of time the operator worked prior to the accident. (Temperature and wind
chill index are critical to operator endurance.)
Specify if the victim’s clothing became entangled in the machine.
Specify if the victim was struck with an object thrown by the snow thrower or by part of the
machine itself.
Indicate if the victim slipped or fell while operating or attending to the snow thrower.
Specify if the victim was filling the tank with gasoline.
Specify if the victim was making repairs or adjustments to the machine.

D. Description of Product
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o

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Identify product type, dimensions, manufacturer, brand, model, and serial number.
Specify snow thrower dimensions (especially discharge chute opening if involved in accident
e.g., radius, length, width, distance to impeller).
Identify product labeling, including product certification (type and year).
Identify power source (gasoline engine or electric motor), engine/motor capacity (horsepower,
cubic inch displacement, amperage).
Identify propulsion source (push or self-propelled).
Identify whether single-stage or two-stage design; indicate type, number, and operation of
snow thrower controls.
Indicate the method by which the snow thrower was acquired, i.e., bought new or used,
borrowed or rented; specify product age.
Describe the mechanical condition of the snow thrower, including previous repairs,
modifications, malfunctions, abuse of the machine, component failure, or lack of
maintenance.
Characterize any safety devices, especially operator present (safety interlock, deadman)
control and discharge chute guard, and whether the safety devices had any effect on the
injury.
Characterize any accessory devices in place or being used at the time of the accident and
whether these accessories had any effect on the accident.
Specify if all guards, shields, deflectors, and housings were in place.

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o
o
o

Describe the power transmission mechanism (clutches, belt drives, chain drives, etc.)
Specify if the snow thrower overturned during operation.
For electrically -operated snow throwers, indicate whether the electric cord was properly
grounded and if and extension cord was being used.

III. Photographs/ Diagrams of Incident Scene
Photograph or diagram the accident scene to show the product dimensions, as well as site
conditions and location of the product and operator/victim at the time of the accident. For hand injuries,
indicate hand positions in detail.
Photograph the discharge chute, the inside of the collector housing and impeller blade. Provide
dimensions, especially discharge chute opening if involved in hand injury, i.e., radius, length, width,
distance to impeller.
Photograph any safety tags or labeling on the machine.

IV. Obtaining samples and documents related to the investigation
Obtain operator’s instruction manual, if available. Obtain copy of any safety tags, instructions, or
certification labels and dates.

(DATA RECORD SHEET – Attached)

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DATA RECORD SHEET
Investigation Guideline
PRODUCT: Snow Throwers
TASK NUMBER __________________________ INCIDENT DATE ___________________________
1.

Describe the general weather conditions at the time of the incident. (windy, snowing, clear, etc.)
Also record the air temperature, wind, wind chill index.

h
h
h
2.

Record the time of day of the accident and lighting conditions.

h
h
h
3.

What was the surface being cleared (gravel driveway, concrete, etc.), presence of debris, amount
(in inches/feet) of snow on ground, type of snow (wet, dry and powdery), and general ground
conditions (slippery, wet, muddy, icy, slushy).

h
h
h
4.

Was there ice on the ground?

✔ Yes
______
✔ No
______
✔ Don’t know
______
5.

Specify degree of slope if machine was used on an incline.

g
g
6.

Was salt used on snow prior to removal?

✔ Yes
______
✔ No
______
✔ Don’t know
______
7.

Was noise from snow thrower or another source distracting or disorienting to the operator?

✔ Yes, explain: ______________________________________________________
g
______
✔
______ No
✔ Don’t know
______

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8.

Record victim’s age, sex, height, and weight.
____________ Age
____________ Sex
____________ Height
____________ Weight

9.

Was the victim ill or under any medication, drug or alcohol at the time of the accident? Does the
victim have any vision impairment, physical disability, etc.?

10. What was the victim’s experience with and knowledge of product performance?

11. What clothing was the victim wearing at the time of accident? Indicate type, materials, and fit.
We are especially interested in the use of gloves or mittens, type of footwear and sole, and degree
of protection or contribution to the accident because of entanglement in the snow thrower.

12. Record the operating status of the snow thrower at the time of the accident.

13. What caused the injury to the victim?
______ Injured on impeller while clearing discharge chute of snow/ice
Specify hand positioning, protection, and use of an implement.
________________________________________________________________________
______________________________________________________________ _________
______ Injured by an object thrown by the snow thrower
______ Victim slipped or fell while operating or attending to the snow thrower
______ Victim was filling the tank with gasoline
______ Victim was making repairs or adjustments to the machine
______ Other, explain:
____________________________________________________________
________________________________________________________________________
14. Record the amount of time the operator had been using the snow thrower immediately prior to the
accident.

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15. Did the victim’s clothing become entangled in the machine?
______ Yes, explain: ______________________________________________________
______ No
______ Don’t know
16. Product type (check all that apply):
______ Single-stage
______ Dual-stage
______ Manual
______ Electric
______ Gas powered
______ Attachment to lawn tractor
______ Pushed
______ Self-propelled
17. Manufacturer ____________________________________________________________
18. Brand __________________________________________________________________
19. Model __________________________________________________________________
20. Serial number ____________________________________________________________
21. Product labeling, certification (type and year) ____________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22. If powered, record the engine/motor capacity (horsepower, displacement, amperage).

23. Was the snow thrower purchased new or used, borrowed or rented. Specify product age.
______ Purchased new
______ Purchased used
______ Borrowed, from whom? __________________________________________
______ Rented, from where? __________________________________________
If known, product age __________________________________________

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24. Describe mechanical condition of the snow thrower.

25. Record any safety devices present on the snow thrower.

26. Record any accessory devices in place or being used at the time of the accident and whether these
accessories had any effect on the accident.

27. Were all guards, shield deflectors, and housings in place?

28. Describe the power transmission mechanisms (clutches, belt drives, chain drives, etc.).

29. Did the snow thrower overturn?

30. For electrically -operated snow throwers- was the electric cord properly grounded, was an
extension cord being used?