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This illustration shows the "C" Series machines hydrostatic drive hydraulic system in the
HOLD position.
The charge pump sends oil through the demand fan motor and hydraulic oil filter to the charge
pump relief valve, the crossover relief and makeup valves, the park brake solenoid valve, the
two-speed solenoid valve (if equipped), and the implement pilot shutoff valve.
When the engine is started, the pilot ON/OFF solenoid is de-energized. The solenoid valve
directs oil to drain and the park brakes are engaged by spring force. When the operator
depresses the park brake switch, a signal is sent to the Machine ECM. The ECM energizes the
Pilot ON/OFF solenoid. The solenoid valve directs oil to the park brake piston and the pump
control solenoid valves. Charge oil acts against spring force to release the park brakes.
The pump solenoid valves control charge oil to the actuator pistons upon command of the
Machine ECM. The actuator pistons control the swashplates. The angle of the swashplates
control the amount of oil and the direction of oil flow from the pump to the motors.
SERV1833-01 - 54 - Text Reference
07/08