Interpretation ID: nht76-3.48

DATE: 03/30/76

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Pullman Trailmobile

TITLE: FMVSS INTERPRETATION

TEXT: This responds to Trailmobile's March 4, 1976, letter asking if a trailer equipped with one or more axles that have a gross axle weight rating (GAWR) of 24,000 pounds or more is excluded from the requirements of Standard No. 121, Air Brake Systems.

Section S3. of Standard No. 121 provides in part that any vehicle manufactured before September 1, 1977, that has a GAWR for any axle of 24,000 pounds or more is excluded from the standard. The determination of GAWR is made by the vehicle manufacturer (49 CFR 571.3) and must be based on the capabilities of the axle system at 60 mph. Because the determination is made by the vehicle manufacturer, the NHTSA is unable to say that the components you mention in your letter would necessarily constitute an axle system with a GAWR of 24,000 pounds.

YOURS TRULY,

Pullman Trailmobile

March 4, 1976

Mr. Sidney F. Williams, Jr. National Highway Traffic Safety Administration Department of Transportation

Regarding our telephone conversation of March 3rd, would you confirm our discussion that a van trailer, having an axle rated at 24,000 pounds GAWR, based on adequate springs, axle beam, bearings, etc. and tires per Tire and Rim Association 60 MPH Rating would indeed be exempt from the Standard No. 121 "Air Brake Systems".

John R. Pratte Manager Materials Engineering