[Code of Federal Regulations]

[Title 49, Volume 5]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR393.50]



[Page 401-402]

 

                        TITLE 49--TRANSPORTATION

 

                      DEPARTMENT OF TRANSPORTATION

 

PART 393_PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION--Table of 

Contents

 

                            Subpart C_Brakes

 

Sec. 393.50  Reservoirs required.



    (a) Reservoir capacity for air-braked power units manufactured on or 

after March 1, 1975, and air-braked trailers manufactured on or after 

January 1, 1975. Buses, trucks, and truck-tractors manufactured on or 

after March 1, 1975, and air-braked trailers manufactured on or after 

January 1, 1975, must meet the reservoir requirements of FMVSS No. 121, 

S5.1.2, in effect on the date of manufacture.

    (b) Reservoir capacity for air-braked vehicles not subject to FMVSS 

No. 121 on the date of manufacture and all vacuum braked vehicles. Each 

motor vehicle using air or vacuum braking must have either reserve 

capacity, or a reservoir, that would enable the driver to make a full 

service brake application with the engine stopped without depleting the 

air pressure or vacuum below 70 percent of that indicated by the air or 

vacuum gauge immediately before the brake application is made. For the 

purposes of this paragraph, a full service brake application means 

depressing the brake pedal or treadle valve to the limit of its travel.

    (c) Safeguarding of air and vacuum. Each service reservoir system on 

a motor vehicle shall be protected against a loss of air pressure or 

vacuum due to a failure or leakage in the system between the service 

reservoir and the source of air pressure or vacuum, by check valves or 

equivalent devices whose proper functioning can be



[[Page 402]]



checked without disconnecting any air or vacuum line, or fitting.

    (d) Drain valves for air braked vehicles. Each reservoir must have a 

condensate drain valve that can be manually operated. Automatic 

condensate drain valves may be used provided (1) they may be operated 

manually, or (2) a manual means of draining the reservoirs is retained.



[70 FR 48052, Aug. 15, 2005]