Interpretation ID: aiam2248
Manager Materials Engineering
Pullman Trailmobile
200 East Randolph Drive
Chicago
IL 60601;
Dear Mr. Pratte: This responds to Trailmobile's March 4, 1976, letter asking if 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 vehicl 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, Frank Berndt, Acting Chief Counsel