PAD-THRUST 3U2837 - Caterpillar

Main Hydraulic Schematic
Illustration 1 g01098090
(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 (left pump) (23) Solenoid valve (swing parking brake) (24) Hydraulic activation valve (25) Solenoid valve (hydraulic activation) (26) Left pump (view from shaft end) (27) Travel speed solenoid valve (28) Pilot oil manifold (29) Drain filter (30) Pilot relief valve (31) Pilot filter (32) Right pump (view from shaft end) (33) Pilot pump (34) Slow return check valve (35) Bypass check valve (36) Pressure sensor (right 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 g00748918
Pump compartment (26) Left pump (32) Right pump (33) Pilot pump (37) Proportional reducing valve (power shift pressure) (41) Delivery line (right pump) (42) Delivery line (left 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 right pump (32) and left 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 g00748919
Main control valve (18) Main relief valve (43) Right control valve body (44) Left control valve bodyRight pump (32) and left pump (26) are variable displacement piston pumps. The performance of both pumps is equal.Right pump (32) is directly connected to the engine by a flexible coupling. The right pump delivers oil to the right control valve body (43) of the main control valve. Left pump (26) is mechanically connected to the right pump through gears. The left 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 right 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