COMPRESSED AIR AND BRAKE SYSTEM OPERATION (Contd)
The primary constant pressure system is made up of the following components:
PRIMARY AIR PRESSURE GAUGE - Indicates amount of air pressure in primary system.
LIMITING VALVE - Serves three functions:
Regulates signal air pressure going to front brake chambers so rear brakes are applied first.
Regulates signal air pressure to front brake chambers so operator has control over amount of braking.
Releases air pressure in front brake chambers directly to vent in the valve when brake pedal is released.
RONT BRAKE CHAMBERS - Converts air pressure to mechanical force which applies front service brakes.
PRIMARY RESERVOIR LOW AIR PRESSURE SWITCH - Activates warning buzzer and warning light when air
pressure goes below 60 psi (414 kPa).