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| Illustration 1 | g00887086 |
Pilot system (1) Pilot manifold (2) Pilot relief valve (high pressure circuit) (3) Pilot accumulator (4) Solenoid valve (boom float) (5) Solenoid valve (swing parking brake) (6) Solenoid valve (bucket bottom dump close) (7) Solenoid valve (bucket bottom dump open) (8) Control valve (travel parking brake and dual pressure) (9) Ladder position solenoid valve (10) Swing parking brake (11) Swing dual pressure relief valve (12) Speed sensor (swing) (13) Travel motors (14) Machine control module (15) Pressure reducing valve (low pressure circuit) (16) Solenoid valve (swing signal) (17) Swing control valve (18) Shuttle valve (19) Boom float relay (20) Vital Information Management System (VIMS) (21) Pressure switch (swing parking brake) (22) Pressure switch (Automatic Engine Speed Control) (23) Pressure switch (boom float) (24) Pressure switch (travel alarm) (25) Load sensing signal relief valve (26) Proportional reducing valve (power shift pressure) (27) Solenoid valve (engine cooling fan) (28) Solenoid valve (hydraulic cooling fan) (29) Pilot resolver shuttle valve (30) Solenoid valve (warm-up) (31) Solenoid valve (boom float)(front shovel) (32) Front control valve (33) Engine Control Module (ECM) (34) Pilot oil flow to the control valves (35) Pilot oil flow to the pilot valve spools (36) Swivel (37) Pilot oil flow to the control valves (38) Pilot hydraulic oil filter (39) Left automatic track tensioning system (40) Hydraulic activation control selector valve (41) Right automatic track tensioning system (42) Pilot oil flow to the pilot valve spools (43) Pilot gear pump | |
The pilot hydraulic system provides pilot oil to the implement control circuit, the swing control circuit, and the travel control circuit. The pilot oil in these control circuits physically moves the spools in the main control valves in order to initiate the desired function. The pilot hydraulic system provides pilot oil to the automatic track tensioning system and the power shift system.
The pilot gear pump is a small gear type pump that is mounted on the output shaft of the radiator cooling piston pump. The radiator cooling piston pump is located on the top left corner of the pump drive.
The output oil from the pilot gear pump passes through a pilot hydraulic oil filter. The pilot hydraulic oil filter is mounted near the pilot gear pump. From the pilot hydraulic oil filter, the pilot oil splits into three circuits.
The first circuit is downstream from the pilot hydraulic oil filter. This circuit supplies oil to the proportional reducing solenoid valves (26) in the power shift system. The proportional reducing solenoid valves (26) control power shift pressure to the implement piston pumps.
Note: Machines (S/N: 7LL1-63) have two proportional reducing solenoid valves (26). Machines (S/N: 7LL64-UP) only have one proportional reducing solenoid valve (26).
The oil that is not used by the circuit for the hydraulic power control system flows into the pilot manifold. The two remaining circuits use oil from the pilot manifold.
One circuit supplies pilot oil to the automatic track tensioning system in order to maintain the track tension. The second circuit supplies pilot oil to the pilot control system. The force of the pilot oil in the pilot control system physically moves the spools in the main control valves in order to initiate the desired function.