LEVER 1152214 - Caterpillar

Illustration 1 g01525241
(1) Displacement change valve for the left travel motor (2) Displacement change valve for the right travel motor (3) Line (4) Swing parking brake (5) Implement/swing pressure switch (6) Travel pressure switch (7) Main control valve (8) Passage (9) Passage (10) Passage (11) Passage (12) Stick drift reduction valve (13) Boom I control valve (14) Boom drift reduction valve (15) Left travel control valve (16) Right travel control valve (17) Swing priority valve (18) Combined flow valve (19) Stick regeneration valve (20) Main relief valve (21) Passage (22) Straight travel control valve (23) Passage (24) Passage (25) Passage (26) Pilot control valve (travel) (27) Line (28) Boom regeneration valve (29) Pressure switch (30) Shock reducing valve (31) Line (32) Boom priority valve (33) Line (34) Pilot control valve (stick and swing) (35) Pilot control valve (bucket and boom) (36) Line (37) Line (38) Travel speed solenoid valve (39) Solenoid valve for swing parking brake (40) Valve (41) Hydraulic activation control valve (42) Pilot manifold (43) Passage (44) Passage (45) Passage (46) Passage (47) Pilot relief valve (48) Pilot filter (49) Line (50) Line (51) Line (52) Idler pump (53) Drive pump (54) Pilot pump (55) Proportional reducing valve (56) Passage (57) PassagePilot Oil Circuit
In the pilot system, the output flow from pilot pump (54) performs the following functions.
Create pilot oil pressure in order to control the output flows of the main pumps.
Provide pilot oil pressure to the pilot control valves for implements, swing, and travel in order to perform machine operations.
Create pilot oil pressure in order to automatically operate the control devices.Oil from pilot pump (54) flows through line (50) to pilot filter (48). Then, the oil divides into lines (51) and (49). Line (49) enters pilot manifold (42) and the oil divides into passage (43), passage (45), and passage (46) .The pressure within the pilot system is limited by pilot relief valve (47) that is built into pilot filter (48) .Power Shift System
The pilot oil from line (51) flows to proportional reducing valve (55) that is mounted on the main pump. The oil flows from the proportional reducing valve as power shift pressure. This oil flows through passage (57) as signal pressure to the regulators of the drive pump (53) and the idler pump (52) in order to control the pump output. For additional information, refer to Systems Operation, "Solenoid Valve (Proportional Reducing) (Power Shift System)".Pilot Control Valve Circuits
The pilot oil for passage (45) flows through valve (40) and passage (44) to line (36). Then, the oil flows to the following pilot control valves through the respective pilot lines: travel (26), stick and swing (34) and bucket and boom (35). When any of the pilot control valves are operated, the pilot oil flows to the selected valve within the main control valve. The pilot oil shifts the stem of the selected control valve in order to operate a cylinder or a motor.The following example is given for the BOOM LOWER operation and the BOOM RAISE