COMPRESSED AIR AND BRAKE SYSTEM OPERATION (Contd)
Secondary Service Airbrake System Operation.
The secondary service airbrake system is made up of two subsystems:
Secondary constant pressure system provides continuous air pressure to:
Rear relay valve.
Spring brake air reservoir.
Spring parking brake valve.
Secondary signal system serves three functions:
Contains air pressure only when operator steps on brake pedal.
Is regulated by various valves to control amount of braking.
Provides pressure to apply the rear two service brakes and the intermediate and rear axles
stamped with B. Service brakes on the rear axle are piggybacked to spring brakes but operate
indeoendentlv of them.