Interpretation ID: aiam2197
Supervising Engineer
Oshkosh Truck Corporation
P.O. Box 2566
Oshkosh
WI 54901;
Dear Mr. Lanzdorf: This responds to Oshkosh Truck Company's January 22, 1976, questio whether a vehicle complies with S5.1.1 of Standard No. 121, *Air Brake System*, when it is moving must also comply with the requirement when it is stationary. Section S5.1.1 specifies an air compressor of sufficient capacity to increase air pressure in the supply and service reservoirs from 85 p.s.i. to 100 p.s.i. within a limited period when the engine is operating at the vehicle manufacturer's maximum recommended rpm.; Section S5.1.1 does not specify whether or not the vehicle is moving a a test condition for the requirement. In view of the absence of this test condition, the NHTSA will resolve differences in this test condition in the manufacturer's favor if they affect the outcome of testing.; Yours truly, Richard B. Dyson, Assistant Chief Counsel