ANGLE 8W5558 - Caterpillar

Illustration 2 g03816714
Propel System Hydraulic Schematic (1) Relief valve (2) Flushing spool (3) Axle motor (4) Relief valve (5) Flushing spool (6) Drum motor (7) Parking brake (8) Charge pressure tap (9) Charge filter (10) From steering pump (11) Neutral start switch (12) Reverse combination valve (13) Forward combination valve (13) Forward combination valve (14) Axle rotating group (15) Bypass valve (16) Interlock solenoid (17) Charge relief valve (18) Drum rotating group (19) Forward combination valve (20) Reverse combination valve (21) Test manifold (22) Hydraulic tank (23) Filter bypass valve (24) Return filter (25) Suction strainer (26) From vibratory manifold port "T" (27) To steer/vibe pumps (28) Oil cooler (29) S O S tap (30) Charge filter bypass valveThe above illustration shows the propel system operating under the following conditions:
The parking brake switch is in the OFF position.
The machine is traveling in the forward direction.When the parking brake switch is in the OFF position, interlock solenoid (16) is energized. In this case, the interlock valve shifts, and charge oil is directed to the parking brake (7) piston cavity. The charge pressure overcomes the spring force in the piston, and the parking brake is released. Charge oil is also sent to the direction control spools in rotating group (14) and (18) .When the propel lever is moved into the forward range, the direction control spools shift. In this case, charge oil is directed into the forward side of the servo pistons. The pressure in the forward side of the servo pistons causes the pump servos to move. This movement changes the angle of the swashplate in rotating groups (14) and (18). The farther the propel lever is moved forward, the greater the swashplate angle increases. This increase in swashplate angel causes a greater oil flow from the propel pump. Supply oil from axle rotating group (14) flows to the following locations:
Forward combination valve (13)
Port "MA" of test manifold (21)
The forward side of axle motor (3)
The forward side of flushing spool (2) The pressure differential between the forward and reverse sides of axle motor (3) causes the motor to turn. After turning the axle motor (3), oil at a reduced pressure flows to the following locations:
The reverse side of flushing spool (2)
Port "MB" of test manifold (21)
Reverse combination valve (12)
The reverse side of axle rotating group (14) Supply oil from drum rotating group (18) flows to the following locations:
Forward combination valve (19)
Port "MC" of test manifold (21)
The forward side of flushing spool (5)
The forward side of drum motor (6) The pressure differential between the forward and reverse sides of drum motor (6) causes the motor to turn. After turning the drum motor (6), oil at a reduced pressure flows to the following locations:
The reverse side of flushing spool (5)
Port "MD" of test manifold (21)
The reverse side of drum rotating group (18)
Reverse combination valve (20) The orifices in test manifold (21) modulate large pressure differences by allowing oil to transfer between the axle and drum drive circuits. In effect, the balance orifices