Main Hydraulic System
Main Hydraulic Schematic
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| Illustration 1 | g01440772 |
(1) Left swing motor (2) Right swing motor (3) Left travel motor (4) Right travel motor (5) Boom cylinder (6) Relief valves (grapple rotate and hydraulic cab riser) (7) Grapple rotator (8) Counterbalance valve (left) (9) Counterbalance valve (right) (10) Boom lowering control valve (11) Proportional reducing valve for hydraulic cab riser (12) Solenoid valve (grapple rotate) (13) Grapple cylinder (14) Pilot control valve (travel) (15) Swivel (16) Main control valve (17) Pilot control valve (stick and swing) (18) Pilot control valve (boom and grapple) (19) Main relief valve (20) Stick cylinder (21) Pressure reducing valve (boom and swing priority) (22) Rotator pump (23) Generator pump (24) Pressure sensor (drive pump) (25) Generator motor (26) Stick lowering control valve (27) Slow return check valve (28) Bypass check valve (29) Oil cooler (30) Travel speed solenoid valve (31) Solenoid valve (swing parking brake) (32) Valve (33) Solenoid valve (hydraulic activation) (34) Accumulator (35) Drive pump (36) Idler pump (37) Pilot pump (38) Proportional reducing valve (power shift pressure) (39) Cooling pump (40) Fan motor (41) Solenoid (reverse fan) (42) Hydraulic oil tank (43) Return filter (44) Case drain filter (pump) (45) Pilot filter (46) Case drain filter (fan motor, swing motors, and travel motors) (47) Pressure sensor (Idler pump) (48) Reducing valve (49) Shockless valve (50) Anti-drift valve (51) Accumulator (52) Emergency valves (53) Slow return valve (54) Hydraulic cab riser cylinder (55) Manual boom lowering valve | |
Hydraulic Pump Flow and Pressure Control System
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| Illustration 2 | g01151267 |
Pump compartment (35) Drive pump (36) Idler pump (38) Proportional reducing valve (power shift pressure) | |
This machine is driven and controlled by the following systems.
- The main hydraulic system controls the cylinders, the travel motors and the swing motors.
- The pilot hydraulic system supplies oil to the main pumps, the main control valve, the swing brakes and the travel motors.
- The electronic control system controls the outputs of the engine and pump.
- The hydraulic oil cooling system provides oil to the fan motor in order to cool the hydraulic oil and engine coolant.
The main hydraulic system delivers oil flow from idler pump (36) and drive pump (35) in order to control the following components: grapple cylinder (13), stick cylinder (20), boom cylinders (5), right travel motor (4), left travel motor (3), left swing motor (1) and right swing motor (2).
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| Illustration 3 | g01149223 |
Main control valve (19) Main relief valve (48) Right control valve body (49) Left control valve body | |
Idler pump (36) and drive pump (35) are axial piston pumps. The performance of both pumps is equal.
Drive pump (35) is directly connected to the engine by a flexible coupling. The drive pump delivers oil to the left control valve body (49) of the main control valve. Idler pump (36) is mechanically connected to the drive pump through gears. The idler pump delivers oil to the right control valve body (48) of the main control valve. Pilot pump (37) is a gear pump that supplies oil to the pilot hydraulic system. Pilot pump (37) is coupled directly to idler pump (36). Cooling pump (39) supplies oil to the oil cooling system. Cooling pump (39) is coupled directly to the engine 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 approximately identical to the engine horsepower.
When no work is being performed, pump oil flows through main control valve (16) and into hydraulic tank (42). The main control valve sends a negative flow control signal to each main pump regulator in order to destroke the pump to the minimum output flow.
If an operation is being performed, main control valve (16) directs pump oil to the respective cylinders (boom, grapple, and stick) and/or motors (swing and travel). Main control valve (16) contains numerous valve stems, passages, check valves, and orifices in order to carry out a single operation or a combined operation. The working pressure of the main hydraulic system is regulated by main relief valve (19).
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| Illustration 4 | g01437863 |
Cab (50) Left travel lever/pedal (51) Right travel lever/pedal (52) Monitor panel (53) Joystick (stick and swing) (54) Joystick (boom and grapple) (55) Engine speed dial | |
The pilot hydraulic system receives oil flow from pilot pump (37). 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 (37) to the pilot oil manifold. 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 (53), joystick (54), left travel lever/pedal (50) and/or right travel lever/pedal (51) are moved from the NEUTRAL position, the pilot oil flows through the pilot control valves to the corresponding spools at the main control valve (16) .
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 (36) or drive pump (35) 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 engine and pump controller receives input signals from various components on the machine. The engine and pump controller processes the input signals. The engine and pump controller then sends an electrical signal to proportional reducing valve (38) at the idler pump regulator in order to regulate the power shift pressure. The power shift pressure controls the output flow of idler pump (36) and drive pump (35). 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 in order to perform the following operations.
- Pilot signal pressure activates the Automatic Engine Speed Control (AEC) system. This 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 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".
Hydraulic Cab Riser
Operation of Hydraulic Cab Riser
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| Illustration 5 | g01449747 |
(1) Manual lowering valve (2) Manual lowering valve (3) orifice (4) Valves (5) Pilot operated directional control valve (6) Valves (7) Valve group (8) Hydraulic line (9) Hydraulic line (10) Cab riser cylinder (11) Shockless valve (12) Reducing valve (13) Shockless valve (14) Anti-drift valve (15) Pilot line (16) Accumulator (17) Hydraulic line (18) Valve group (19) Solenoid (20) Solenoid (21) Hydraulic line (22) Hydraulic line (23) Pilot manifold (24) Hydraulic tank (25) Grapple rotate pump (26) Hydraulic line (27) Pilot pump | |
The circuit for the hydraulic cab riser allows the cab to be raised or lowered. The hydraulic circuit for the cab riser is controlled by electronic switches that are located on the joystick. The electric switches operate solenoid valves (18).
Oil from grapple rotate pump (25) supplies oil to cylinder (10). The grapple rotate pump is driven by gears that are directly coupled to the drive pump.
When the hydraulic circuit for the cab riser is not active oil from the grapple pump flows to valve (7). The oil then flows through line (17) to the hydraulic tank (24) .
When the cab riser switch is depressed, solenoid (19) causes the cab to rise. Solenoid (20) causes the cab to lower.
Cab Raise
Pilot pump (27) supplies oil to the pilot manifold (23). When solenoid (19) is activated, pilot oil from the pilot manifold flows through line (22) to valve group (18). Then, the pilot oil flows through line (15), through valve (13), through valve (12), and to valve (5). When valve (5) shifts, oil from the grapple rotate pump (25) flows through line (26) and then through valve (5). From valve (5), the oil flows through line (9), and through valve (14) to cylinder (10), causing the cylinder to extend and the cab to lift. Return oil from cylinder (10) flows through valve (5) to the hydraulic tank.
Cab Lower
Pilot pump (27) supplies oil to the pilot manifold (23). When solenoid (20) is activated, pilot oil from the pilot manifold flows through line (22) to valve group (18). The pilot oil then flows through line (21), through valve (11) to valve (5) and to valve (14). Pilot oil shifts a spool in valve (14) which allows valve (14) to open. Pilot oil shifts valve (5) which allows oil from the grapple rotate pump (25) to flow through line (26) then through valve (5). From valve (5), the oil moves through line (8) to cylinder (10). The cylinder retracts and the cab lowers. Because valve (14) is now open, the return oil from cylinder (10) flows through valve (14), through valve (5), and to the hydraulic tank.
Valves (4) are used to direct oil from the grapple rotate pump to the tank when the cab riser is not being used.
Valves (6) are used as pressure relief valves when the cab riser is being used.
There are two manual lowering valves (1) and (2) for the hydraulic cab riser. The manual lowering valves can be used to lower the cab when there is no pilot pressure. One manual lowering valve is located in the cab near the operator's right foot. The other manual lowering valve is located in the battery compartment.