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| Illustration 1 | g06106090 |
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(1) Pilot control valve (stick and swing)
(2) Pilot control valve (bucket and boom) (3) Boom cylinder (4) Pressure sensor (boom cylinder head end) (5) Heel cylinder (6) Stick cylinder (7) Grapple cylinder (8) Swing motor (9) Left travel motor (10) Right travel motor (11) Pressure sensor (boom down control) (12) Implement pressure switch (13) Pressure sensor (swing control) (14) Main control valve (15) Grapple open/close control valve (16) Negative Flow Control Valve (17) Bypass check valve (18) Oil cooler (19) Slow return check valve (20) Stick drift reduction valve (21) Swivel (22) Solenoid manifold group (23) Grapple rotate control valve (24) Pilot control valve (travel) (25) Left travel control valve pressure switch (26) Right travel control valve pressure switch (27) Heavy lift solenoid valve (28) Pilot oil manifold (29) Travel speed solenoid valve (30) Swing brake solenoid valve (31) Valve (32) Solenoid valve (hydraulic lockout) (33) Accumulator (34) Boom drift reduction valve (35) PRV for boom regeneration valve (36) Pressure sensor (drive pump) (37) Pressure sensor (idler pump) (38) Main relief valve (39) Pilot relief valve (40) Pilot filter (41) Accessory pump (42) Idler pump (43) Pilot pump (44) Drive pump (45) Fan control solenoid (46) Proportional reducing valve (power shift pressure) (47) Drain filter (48) Hydraulic tank | |
Swing Motor with Fine Swing (If Equipped)
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| Illustration 2 | g06067065 |
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Partial schematic (8) Swing motor (14) Main control valve (42) Idler pump (43) Pilot pump (44) Drive pump (48) Hydraulic tank (49) Fine swing solenoid | |
Hydraulic Schematic with Heavy Lift
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| Illustration 3 | g06067070 |
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Partial schematic (14) Main control valve (28) Pilot oil manifold (38) Main relief valve (43) Pilot pump (48) Hydraulic tank (50) Heavy lift solenoid | |
Hydraulic Pump Flow and Pressure Control System
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| Illustration 4 | g06067101 |
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Pump compartment (42) Idler pump (43) Pilot pump (44) Drive pump (46) Proportional reducing valve (power shift pressure) (51) Delivery line (drive pump) (52) 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 pumps.
The main hydraulic system delivers oil flow from idler pump (42) and drive pump (44) to control the following components: heel cylinder (5), stick cylinder (6), boom cylinders (3), grapple cylinders (7), right travel motor (10), left travel motor (9), and swing motor (8).
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| Illustration 5 | g06067104 |
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Main control valve (14) Main control valve body (38) Main relief valve | |
Drive pump (44) and idler pump (42) are variable displacement piston pumps. The performance of both pumps is equal.
Drive pump (44) is directly connected to the engine by a flexible coupling. Idler pump (42) is mechanically connected to the drive pump through gears. The drive pump and the idler pump deliver oil to main control valve body (14). The drive pump delivers oil to the left travel control valve, the boom I control valve, the heel control valve, and the stick II control valve. The idler pump delivers oil to the right travel control valve, the boom II control valve, the swing control valve, and the stick I control valve. Pilot pump (43) is a gear pump that supplies oil to the pilot hydraulic system. Pilot pump (43) is mechanically connected to idler pump (42) through gears. 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 identical to the engine horsepower.
When no work is being performed, pump oil flows through main control valve (14) and into hydraulic tank (48). The main control valve sends a negative flow control signal to each main pump regulator to destroke the pump to the minimum output flow.
If an operation is being performed, main control valve (14) directs pump oil to the respective cylinders (boom, heel, grapple, and stick) and/or motors (swing and travel). Main control valve (14) contains numerous valve stems, passages, check valves, orifices, and electronic solenoids to carry out a single operation or a combined operation. The working pressure of the main hydraulic system is regulated by main relief valve (38).
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| Illustration 6 | g06067111 |
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Cab (53) Monitor panel (54) Joystick (stick and swing) (55) Joystick (heel and boom) (56) Left travel lever/pedal (57) Right travel lever/pedal (58) Engine speed dial | |
The pilot hydraulic system receives oil flow from pilot pump (43). The pilot hydraulic system controls the following functions.
- The pilot hydraulic system controls the operation of the implement control valves.
Pilot oil flows from pilot pump (43) through pilot manifold (28). The pilot oil then flows to the pilot control valves for machine operation (implement operations, swing operations, and travel operation). These pilot control valves are activated by the joysticks and the travel levers/pedals.
When joystick (54), joystick (55), left travel lever/pedal (56) and/or right travel lever/pedal (57) are moved from the NEUTRAL position, the pilot oil flows through the pilot control valves to the corresponding spools at the main control valve (14).
The pilot pressure oil at that end of the valve spool forces the valve spool to shift. The pilot oil on the other end of the valve spool drains to the hydraulic tank. When the valve spool shifts, oil is then delivered from idler pump (42) or drive pump (44) to the cylinders and motors.
Thus, pilot oil drives each system of the main control valve.
- The pilot hydraulic system controls the output flow of the main pumps.
During machine operation, pilot pressure is sent to the main pump regulators as a signal pressure. This signal pressure is called power shift pressure. The machine ECM receives input signals from various components on the machine. The machine ECM processes the input signals. The machine ECM then sends an electrical signal to proportional reducing valve (46) to regulate the power shift pressure. The power shift pressure controls the output flow of idler pump (42) and drive pump (44). Power shift pressure adjusts the output flow of the main pumps in accordance with the engine speed. For more information concerning power shift pressure, refer to Systems Operation, "Pilot Hydraulic System".
- The pilot hydraulic system generates signal pressure to perform the following operations.
- Pilot signal pressure activates the Automatic Engine Speed Control (AEC) system. This action causes functions to automatically reduce the engine speed when no hydraulic operation is called for.
- Pilot signal pressure releases the swing parking brake.
- Pilot signal pressure will automatically change the travel speed to either HIGH or LOW in accordance with the hydraulic system load.
- Pilot signal pressure operates the straight travel control valve. This action maintains straight travel during the operation of an implement.
- Pilot signal pressure controls the operation of the valves that can be used during a loading operation or a trenching operation.
For more information concerning the pilot hydraulic system, refer to Systems Operation, "Pilot Hydraulic System".