Propel System in Neutral Position
(1) Flushing valve. (2) Charge relief valve. (3) Line from charge filter. (4) Tandem propel pump. (5) Axle propel motor. (6) Servo control valves. (7)
Drum drive motor. (8) Brake interlock valve. (9) Unfiltered charge oil. (10) Parking brake and speed shift valve. (11) Thermal bypass valve. (12)
Hydraulic oil tank. (13) Line from charge filter relief. (14) Hydraulic oil cooler.
When the engine is running, tandem propel pump (4) and the
steering pump are rotating. The steering pump provides the
charge oil for the propel system. The maximum charge oil
pressure in neutral Is controlled by charge relief valve (2) in
flushing valve (1). The charge oil is used as make-up oil for
propel pump and motor leakage, cooling for the pump and
motors, to move the pump swashplates, to release the parking
brake and to shift motor displacement for high and low speeds.
Servo control valves (6) are connected to each other by a
linkage rod. Both control valves always move together. The
front pump supplies oil for drum drive motor (7) and the rear
pump supplies oil to axle propel motor (5).