Interpretation ID: aiam1578
General Manager
Rite-Way Inc. of Indiana
4301 Bluffton Road
Fort Wayne
IN 46809;
Dear Mr. Limbaugh: This responds to your July 29, 1974, request for a copy of ou temporary exemption regulations, and for information on the effective date of Standard No. 121, *Air brake systems*, as it applies to vehicles with a driven front axle. I have enclosed a copy of NHTSA's 'Temporary Exemption' regulations, Part 555 of Title 49, the Code of Federal Regulations.; Standard No. 121 applies to trucks manufactured on or after March 1 1975, with only limited exceptions. Fire trucks are excluded from regulation until September 1, 1975, and vehicles with an overall width of 108 inches or more or a gross axle weight rating for any axle of 24,000 pounds or more, are excluded until September 1, 1976.; In addition, a truck manufactured before September 1, 1975, that has front steerable axle with a gross axle weight rating of 16,000 pounds or more, or a front steerable drive axle, is exempt from some of the stopping distance requirements if its brakes conform to a certain retardation force and values. Aside from these exemptions, any truck with a front steerable drive axle must meet all other requirements of the standard.; Yours truly, Richard B. Dyson, Acting Chief Counsel