Brake Relay Valve (R-14); Antilock Traction Relay Valve (Atr-6); Spring Brake Valve (Sr-7) - PREVOST H3-41 Maintenance Manual

SECTION 12: BRAKE AND AIR SYSTEM
13.7

BRAKE RELAY VALVE (R-14)

The primary air system includes two brake relay valves being supplied by
the dual brake valve, and which function is to speed up the application and
release of the service brakes.
One R-14 valve located above the drive axle supplies the drive axle service
brake air line, while the other R-14 valve supply the tag axle service brake
air line and act as interlock valves. These valves are accessible from under
the vehicle at the level of the tag axle.
Maintenance and repair information on these valves is supplied in the
applicable booklet, found on your Technical Publications USB flash drive,
under reference number Bendix SD-03-1064.
13.8

ANTILOCK TRACTION RELAY VALVE (ATR-6)

The ATR-6 Antilock Traction Relay valve is a service relay valve fitted with
a modified cover containing a control solenoid. It contains both air and
electric components to provide the service braking and traction control
(differential braking) as well as ESC advanced stability system ABS
functions. It is located above the front axle.
Maintenance and repair information on these valves is supplied in the
applicable booklet, found on your Technical Publications USB flash drive,
under reference number Bendix SD-13-4861.
13.9

SPRING BRAKE VALVE (SR-7)

The spring brake valve is located above the drive axle. The SR-7
Modulating Valve is used in conjunction with a dual air brake system and
spring brake actuator and performs the following functions:
• Provides a rapid application of the spring brake actuator when parking.
• Modulates the spring brake actuator application using the dual brake
valve should a primary failure occur in the service brake system.
• Prevents compounding of service and spring forces.
Maintenance and repair information on the spring brake valve is supplied in
the applicable booklet, found on your Technical Publications USB flash
drive, under reference number Bendix SD-03-9043.
22 PA1621 Maintenance Manual All Series | Revised June 2020