1-19. BRAKE SYSTEM
Figure 1-14. Brake System
The vehicle is equipped with a brake system which complies with the Federal Motor
Vehicle Safety Standard (FMVSS) 121.
The brake system is made up of an air
compressor, air dryer, primary and secondary air tanks, and several valves which control
the application and release of the brakes.
(1) The air compressor (1, Figure 1-14) supplies approximately 120 psi (827 kPa) to the
air dryer (2).
(2) The air dryer contains a heating element and a desiccant cartridge to remove
moisture from the air before it is delivered to the primary air tank (3) and secondary air
(3) The foot control valve (5) receives pressurized air from both the primary and
secondary air tanks. The foot control valve is a two circuit design, with one set of ports
directing air to the front brakes from the secondary air tank and a second set of ports
directing air to the rear brakes from the primary air tank. The plumbing between the
primary and secondary air tanks is designed to allow controlled braking in the event of
a failure in either the primary (rear brakes) or secondary (front brakes) brake circuit.
When air pressure in the wet tank (6) falls below a preset limit, pres-surized air, normally
used for the CTIS, is redirected to the primary brake circuit.