ROD 1261827 - Caterpillar

Hydraulic Schematic For Pilot Oil
Illustration 1 g01017854
(1) Solenoid valve (swing parking brake) (2) Swing parking brake (3) Swing parking brake (4) Displacement change valve (left travel) (5) Displacement change valve (right travel) (6) Pilot line (7) Pilot line (8) Pressure switch (boom raise operation) (9) Stick drift reduction valve (10) Left travel control valve (11) Straight travel control valve (12) Pressure switch (implement and swing) (13) Pressure switch (travel) (14) Right travel control valve (15) Main control valve (16) Boom I control valve (17) Boom drift reduction valve (18) Pilot line (19) Pilot line (20) Pilot line (21) Passage (22) Passage (23) Logic valve (24) Pilot control valve (travel) (25) Main relief valve (26) Pressure control valve (27) Pilot line (28) Pilot control valve (stick and swing) (29) Pilot line (30) Pilot line (31) Pilot filter (32) Line (33) Pilot control valve (bucket and boom) (34) Hydraulic activation control valve (35) Pilot line (36) Passage (37) Passage (38) Solenoid valve (fine control) (39) Passage (40) Upper pump (41) Pilot relief valve (42) Lower pump (43) Travel speed solenoid valve (44) Solenoid valve (swing) (45) Proportional reducing valve (46) Pilot manifold (47) Pilot pumpPilot Oil Circuit
Pilot system oil from pilot pump (47) has the following three main functions: (1) Control main pump output. (2) Operate the main control valves. (3) Create pilot oil pressure in order to achieve various operations.The pilot oil from pilot pump (47) goes through pilot filter (31) and line (30). The pilot oil then enters pilot oil manifold (46). The pilot oil is then separated into the following circuits through respective lines (29) and (35), and passages (36), (37), and (39) .Proportional Reducing Valve Circuit
Pilot oil from passage (39) goes to proportional reducing valve (45). The pilot oil is changed into a hydraulic signal of power shift pressure. The hydraulic signal goes through line (32) to the regulators of main pumps (40) and (42). The hydraulic signal controls the pump output.Note: For more information on the regulators and main pumps, refer to Systems Operation, "Piston Pump (Main)".Pilot Control Valve Circuits
Pilot control valve circuits direct pilot pump oil through pilot filter (31) to hydraulic activation control valve (34). Pilot oil then goes to pilot control valves (24), (28), and (33) .When a pilot control valve is operated, pilot oil goes to the main control valve that is selected. The pilot oil shifts the stem of the selected main control valve in order to operate a cylinder and/or a motor. Boom I control valve (16) is controlled by pilot oil from line (19) or line (27) .When the boom is lowered or the stick is moved inward, the pilot oil from line (18) or line (20) activates boom drift reduction valve (17) or stick drift reduction valve (9) .When the boom control lever is moved to the LOWER position, pilot oil from pilot control valve (33) goes through line (18) to boom drift reduction valve (17). Boom drift reduction valve (17) allows return oil flow from the boom