Interpretation ID: nht79-4.12

DATE: 06/21/79

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: Macdonald Equipment Company

TITLE: FMVSR INTERPRETATION

TEXT: This responds to your January 2, 1979, letter asking whether it is permissible to mount a snow plow on a vehicle when the weight of the snow plow will cause the vehicle to exceed its gross axle weight rating (GAWR). The answer to your question is no.

The GAWR of a vehicle is determined and established by a vehicle's manufacturer and represents a manufacturer's assessment of the maximum weight that each axle can safely sustain. When this weight rating is exceeded by the addition of equipment to a vehicle, the safety of a vehicle is jeopardized. Over a period of time, the excessive weight borne by the axle could result in unusual wear and eventual failure of the axle.

The National Highway Traffic Safety Administration requires manufacturers to label their vehicles with GAWR's to avoid the overload problem that you mention in your letter. The NHTSA has not granted exceptions from this requirement for snow plows. If you mount a snow plow on a new vehicle prior to first purchase, you must be sure that the vehicle continues to comply with all Federal safety standards and regulations. If the weight of the plow exceeds the GAWR of the vehicle, the vehicle would no longer comply with the certification regulation and would not comply with Standard No. 120, Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars. Further, the compliance of other safety standards could be impacted by the addition of that weight.

In the case of used vehicles on which you mount a snow plow, a manufacturer, repair business, distributor, or dealer may not knowingly render inoperative the compliance of a vehicle with the safety standards. The attachment of a snow plow that exceeds the gross axle weight rating would render inoperative the compliance of the vehicle with Standard No. 120. Accordingly, whether a vehicle is new or used, the additional weight of a snow plow that would exceed the GAWR of a vehicle would not be permissible.

The NHTSA understands the budgetary constraints of municipalities. However, financial considerations must be balanced against the potential loss of life that can occur when vehicles are routinely overloaded. Accordingly, vehicles that have snow plows or other devices mounted on them should have sufficient GAWR's to carry their intended load.

Sincerely,

Macdonald Equipment Company

January 2, 1979

Office of the Chief Counsel National Highway Traffic Safety Administration

Gentlemen:

We have talked with your people here in Denver as well as with Mr. Elliot in Washington concerning the mounting of snow plows on trucks and they recommended that we contact your office for an opinion.

We are a disbributor for both a snow plow manufacturer and for a snow plow truck manufacturer and in the course of business we have noticed a trend develop, which we feel needs some clarification. In recent years cities, counties and states agencies responsible for snow removal seem to be purchasing trucks with smaller front axle capacity ratings. This is the result of increased prices on trucks in recent years and the need of these agencies to stay within their budgets.

The result of this trend is that the front axle capacities of these smaller trucks will not allow us to mount a hitch and snow plow on the truck without overloading the front axle or severly limiting the Dump Body capacity to avoid overloading the front axle, which limits the units role in spreading sand on the icy roads.

We would like to know if the weight of the snow plow and hitch must be included when determining the weight on the front axle or if ther is some type of exemption for snow plows. Since snow removal is a necessity in much of our country during the winters and the snow plows are generally on the trucks only in the event of storm it would seem that if there is not an exemption for the snow plows at present, it is an area that some type arrangement needs to be worked out. If the trend to the smaller type trucks with front axles rated at 12,000 pound or less capacity continues and we feel it will, it will be impossible to mount snow plows on most trucks used by these agencies.

Since we feel that we are getting into a situation where front axle load is becoming a question, we would very much appreciate any information or instructions you can give us in this matter. If we can supply you with any further material we would be most happy to do so. Thank you.

Macdonald Equipment Company A. M. Dahm, President