BASE-DESK TOP 2500957 - Caterpillar

Main Hydraulic Schematic
Illustration 1 g01391764
(1) Swing motor (2) Left travel motor (3) Right travel motor (4) Stick cylinder (5) Travel brake valve (left) (6) Travel brake valve (right) (7) Bucket cylinder (8) Boom cylinder (9) Swivel (10) Pilot control valve (travel) (11) Stick drift reduction valve (12) Main control valve (13) Boom drift reduction valve (14) Pressure switch (15) Pressure switch (16) Pilot control valve (swing and stick) (17) Pilot control valve (boom and bucket) (18) Main relief valve (19) Pressure switch (20) Accumulator (21) Reducing valve (boom priority mode or swing priority mode) (22) Pressure sensor (idler pump) (23) Swing brake solenoid valve (24) Valve (25) Solenoid valve (hydraulic lockout) (26) Idler pump (27) Travel speed solenoid valve (28) Pilot oil manifold (29) Drain filter (30) Pilot relief valve (31) Pilot filter (32) Drive pump (33) Pilot pump (34) Slow return check valve (35) Bypass check valve (36) Pressure sensor (drive pump) (37) Proportional reducing valve (power shift pressure) (38) Oil cooler (39) Return filter (40) Hydraulic tankHydraulic Pump Flow and Pressure Control System
Illustration 2 g00673707
Pump compartment (26) Idler pump (32) Drive pump (33) Pilot pump (37) Proportional reducing valve (power shift pressure) (41) Delivery line (drive pump) (42) Delivery line (idler pump)This machine is driven and controlled by the following systems.
The main hydraulic system controls the cylinders, the travel motors and the swing motor.
The pilot hydraulic system supplies oil to the main pumps, the main control valve, the swing brake and the travel motors.
The electronic control system controls the outputs of the engine and pump.The main hydraulic system delivers oil flow from drive pump (32) and idler pump (26) in order to control the following components: bucket cylinder (7), stick cylinder (4), boom cylinders (8), right travel motor (3), left travel motor (2) and swing motor (1).
Illustration 3 g00747481
Main control valve (18) Main relief valve (43) Right control valve body (44) Left control valve bodyDrive pump (32) and idler pump (26) are variable displacement piston pumps. The performance of both pumps is equal.Drive pump (32) is directly connected to the engine by a flexible coupling. The drive pump delivers oil to the right control valve body (43) of the main control valve. Idler pump (26) is mechanically connected to the drive pump through gears. The idler pump delivers oil to the left control valve body (44) of the main control valve. Gear-type pilot pump (33) supplies oil to the pilot hydraulic system. Gear-type pilot pump (33) is directly connected to drive pump (32) by a coupling. All engine output is used to drive these three pumps.As the load pressure increases during working conditions, the main pumps increase the delivery pressure and the pumps decrease the flow rate. The hydraulic horsepower remains constant even though the delivery pressure and the flow rates change. The hydraulic horsepower is approximately identical to the engine horsepower.When no work is being performed, pump oil flows through main control valve (12) and into hydraulic tank (40). The main control valve sends a negative flow