THEORY OF OPERATION - CONTINUED
Transmission Neutralizer Control Valve. The control valve causes the transmission to shift into neutral when the left
brake pedal is pushed. This provides full engine power to the hydraulic system.
Service Brakes. Service brakes are oil-activated, disc-type. Pushing either brake pedal causes pressurized oil from the
brake control valve to push against discs and plates in the brake housing, causing friction. This friction causes the wheel
to turn slower or stop. If the accumulator charging circuit malfunctions, causing pressure to drop below 700 psi (4,826
kPa), the brakes will automatically be activated.
Emergency and Parking Brake Control Valve. This valve controls oil flow from the accumulator to the emergency
and parking brake. It is manually activated by the operator. Pulling out on the parking brake control knob, on the right
side of steering column, causes the brake to be applied. Pushing in on knob causes the brake to release.
EMERGENCY AND PARKING
BRAKE CONTROL VALVE