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Brake Pedal Valve
BRAKE SYSTEM
Multiple wet disc brakes for stopping vehicle movement are contained in the axle-end planetary gear sets.
A brake pump (10, Figure 3) supplies pressurized fluid to the brake hydraulic system. Force on the brake
pedal (5) moves two spools in the brake valve (9). The spools are proportional. The farther the brake pedal
is pushed, the greater the amount of fluid that passes through each spool. One spool ports fluid to brake
pistons in the front axle (3). The other spool ports fluid to brake pistons in the rear axle (1). Pressure on the
brake pistons applies pressure to the brake discs, and this stops axle shaft and wheel rotation.
The brake hydraulic system also contains four accumulators (8). The accumulators hold a volume of
pressurized fluid large enough to allow the brakes to be applied nine times with full pressure, after the
engine has been turned off.
The brake hydraulic system includes a pressure operated transmission cutoff switch (2, Figure 3). Pressing
the brake pedal (5) will open cutoff switch (2). When the transmission cutoff switch in the operator’s cab is
selected, this will cut off current to a solenoid operated hydraulic valve in the transmission. This prevents
operation of the forward clutch in the transmission. This prevents the transmission from driving the wheels
forward when the brake pedal is pressed.
AHS3770L
Figure 3 BRAKE HYDRAULIC CIRCUIT
Reference
Number
Description
1 Rear Axle
2 Transmission Cutoff Switch
3 Front Axle
4Brake
5 Brake Pedal
6 Stop Light Switch
7 Parking Brake
8 Accumulators: Brake
9 Brake Valve
10 Pilot Pump
11 Pilot Supply Line
12 Low Pressure Warning Switch
13 Pilot and Parking Valve
14 Low Pressure Warning Switch
15 Brake and Pilot Filter
Reference
Number
Description
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