Interpretation ID: nht74-2.9

DATE: 03/19/74

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: American Snowblast Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your March 4, 1974, question whether your rotary snowplows, constructed with four-wheel drive and four-wheel steer and a top speed of 35 miles per hour, must be certified to conform to Federal motor vehicle safety standards. You also asked whether "certified brakes" will be sufficient certification to Standard 121, what the effects of a locked transfer case are on an anti-lock system, and what procedure exists to petition for an exemption from the standard.

I have enclosed an information sheet which explains that the vehicles you build for highway use are motor vehicles subject to the standard. The standard applies to the performance of the vehicle as a whole, not just to the brake system. In the event that the vehicles as completed do not actually comply, it is the manufacturer of the vehicle who is responsible.

I have enclosed a copy of the law and regulations explaining the basis for and necessary procedures to apply for a temporary exemption from our safety standards.

With regard to a locked transfer case, S6.1.11 of the air brake standard requires:

S6.1.11 Special drive conditions. A vehicle equipped with an interlocking axle system or a front wheel drive system that is engaged and disengaged by the driver is tested with the system disengaged.

Yours truly,

ATTACH.

March 4, 1974

Department of Transportation - NHTSA

Attention: Sid Williams

Gentlemen:

Please give us your opinion on where we stand with respect to FMVSS-121.

We build large rotary snowplows (brochure enclosed) which are sold primarily to airports. We do build an average of five or so per year for highway plowing, and this is our area of concern.

These machines are air braked, four wheel drive and four wheel steer, have a top speed of 35 m.p.h., and weigh less than 40,000 lbs. but more than 30,000 lbs.

Our questions are: must we certify; will certified brakes be sufficient to certify the vehicle; what are the effects of a locked transfer case on anti-lock; the procedure for petitioning for an exemption, etc.

Sincerely

AMERICAN SNOWBLAST CORPORATION;

D. L. Massy -- Chief Engineer

Enclosure Omitted.