Interpretation ID: aiam1779
Supervising Engineer
Oshkosh Truck Corporation
P.O. Box 560
Oshkosh
WI 54901;
Dear Mr. Lanzdorf: This responds to Oshkosh Truck Company's January 9, 1975, questio whether Standard No. 121, *Air brake systems*, permits the installation of a hand-operated control lever for use in modulating the air in the service brake system in a vehicle which is equipped with a foot-operated service brake control which meets the requirements of the standard.; Standard No. 121 does not include a requirement for a service brak control, and it does not prohibit installation of more than one service brake control. At the same time, several provisions are based on operation of the service brake control(e.t., S5.3.1, S5.7.2.1) and therefore indirectly require a service brake control with certain characteristics. Recently-issued amendments of the emergency brake provisions (effective September 1, 1976) are intended to combine service and emergency brake control in a single service brake control to simplfy (sic) and standardize braking in all new vehicles.; With this in mind, the NHTSA has determined that installation of hand-operated control lever such as you describe does not violate the standard. It may be advisable however, to label this hand-operated lever with a designation other than 'service brake control.' The NHTSA will review this and the other provisions of Standard No. 121 on a continuing basis to determine the advisability f further specifications in the future.; Yours truly, Richard B. Dyson, Assistant Chief Counsel