Figure 1-24. Brake System

TM 9-2320-366-20-1

1-15. BRAKE SYSTEM (CONT)

Figure 1-24. Brake System (Cont)

The foot control valve is operated by the brake pedal (5) and receives pressurized air from both the primary and

secondary air tanks. The foot control valve is a dual activation design, with one set of ports supplying air to the front

brakes from the secondary air tank and another set of ports supplying 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. A booster valve (6) is incorporated

into the primary brake circuit to provide a more rapid braking response. Air from the booster valve is supplied to the

load sensing valve (7) which, in turn, controls air delivery to the relay valve (8). The load sensing valve is mounted

on a crossmember and connected, by a spring and cable, to the load averaging channel. This arrangement of the load

sensing valve and load averaging channel provides a mechanical anti-lock feature to the rear brakes by sending less

air to the rear brakes when the vehicle is not heavily loaded. The relay valve is used to provide the operator with

quicker brake response. An inversion valve (9) redirects air from the secondary brake circuit to the primary brake circuit

in case of loss of pressure in the primary brake circuit. This feature allows control of the spring brakes and prevents

early rear brake lock-up.

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