Interpretation ID: nht87-3.29

TYPE: INTERPRETATION-NHTSA

DATE: NOVEMBER 18, 1987

FROM: DAVIS THEKKANATH -- SR. SUPERVISING ENGINEER, OSHKOSH TRUCK CORPORATION

TO: CHIEF COUNSEL -- NHTSA

TITLE: FMVSS 121

ATTACHMT: MEMO DATED 9-12-88, TO DAVIS THEKKANATH, FROM ERIKA Z. JONES-NHTSA, STD 121

TEXT: Section 5.1.1. of the subject regulation addresses air compressor capacity requirements in terms of pump up time, to bring the reservoir pressure from 85 psi to 100 psi for trucks and buses. What happens when the truck has a trailer behind it? Does the air compressor capacity requirement include the volume of service reservoirs for the trailer too? My conversation this morning with Mr. Richard Carter of your office indicates that only the truck's service reservoirs have to be considered for the pump up time. Please confirm.

Thank you,