[Code of Federal Regulations] [Title 49, Volume 4] [Revised as of October 1, 2002] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR393.40] TITLE 49--TRANSPORTATION CHAPTER III--FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 393--PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION--Table of Contents Subpart C--Brakes Sec. 393.40 Required brake systems. (a) General. A bus, truck, truck tractor, or a combination of motor vehicles must have brakes adequate to control the movement of, and to stop and hold, the vehicle or combination of vehicles. (b) Specific systems required. (1) A bus, truck, truck tractor, or combination of motor vehicles must have-- (i) A service brake system that conforms to the requirements of Sec. 393.52; and (ii) A parking brake system that conforms to the requirements of Sec. 393.41. (2) A bus, truck, truck tractor, or a combination of motor vehicles manufactured on or after July 1, 1973, must have an emergency brake system that conforms to the requirements of Sec. 393.52(b) and consists of either-- (i) Emergency features of the service brake system; or (ii) A system separate from the service brake system. A control by which the driver applies the emergency brake system must be located so that the driver can readily operate it when he/she is properly restrained by any seat belt assembly provided for his/her use. The control for applying the emergency brake system may be combined with either the control for applying the service brake system or the control for applying the parking brake system. However, all three controls may not be combined. (c) Interconnected systems. (1) If the brake systems specified in paragraph (b) of this section are interconnected in any way, they must be designed, constructed, and maintained so that, upon the failure of any part of the operating mechanism of one or more of the systems (except the service brake actuation pedal or valve)-- (i) The vehicle will have operative brakes; and (ii) In the case of a vehicle manufactured on or after July 1, 1973, the vehicle will have operative brakes capable of performing as specified in Sec. 393.52(b). (2) A motor vehicle to which the emergency brake system requirements of Federal Motor Vehicle Safety Standard No. 105 (Sec. 571.105 of this title) applied at the time of its manufacture conforms to the requirements of paragraph (c)(1) of this section if-- (i) It is maintained in conformity with the emergency brake requirements of Standard No. 105 in effect on the date of its manufacture; and (ii) It is capable of performing as specified in Sec. 393.52(b), except upon structural failure of its brake master cylinder body or effectiveness indicator body. (3) A bus conforms to the requirements of paragraph (c)(1) of this section if it meets the requirements of Sec. 393.44 and is capable of performing as specified in Sec. 393.52(b).