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| Illustration 1 | g01213889 |
Work Tool Hydraulic System (1) Auxiliary circuit (2) Accumulator (3) Hydraulic tank (4) Tilt cylinder group (5) Lift cylinders (6) Control circuit for the work tool (7) Gear pump (8) Piston pump (9) Control valve (work tool) (10) Ball valve (11) Return manifold (12) Relief valve (charge oil) (13) Pilot valve (work tool) | |
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| Illustration 2 | g01068265 |
(3) Hydraulic tank (7) Gear pump (9) Control valve (work tool) | |
The piston pump for the hydrostatic system is mounted to the engine. The piston pump for the work tools (8) is mounted to the piston pump for the hydrostatic system. Piston pump (8) supplies the work tool hydraulic system with oil. When the engine speed increases, the speed of pump (8) increases. This causes the pump to move oil to the work tool hydraulic system. Control valve (9) is an closed center control valve.
The pilot oil for the work tool hydraulic system is supplied by the gear pump (7). The gear pump (7) is splined to the drive shaft of the piston pump (8). Oil flows out of pump (7) to the motor for the air conditioner. From the motor for the air conditioner, the oil flows to the fan drive motor. The oil flows through the fan drive motor to the oil filter. From the oil filter, the oil flows to the front section of the piston pump for the hydrostatic system. At the piston pump, the hydraulic oil flows passed the speed sensing valve. In order for the oil to flow to pilot valve (13), all three of the electronic interlocks must be disengaged. In order for oil to flow to pilot valve (13), the hydraulic enable solenoid must be energized.
When the engine starts rotating, pilot oil will supply the accumulator (2). The pilot pump directs pilot oil flow to the speed sensing valve. The oil flows downstream across a one-way flow check valve. The oil will flow directly to the accumulator. No electrical components need to be energized for oil to flow to the accumulator. The pilot oil will also flow to the pilot valve (13). When pilot valve (13) is activated, oil will be directed to control valve (9) in order to shift a control spool to the desired position. Once a control spool shifts, high pressure oil from pump (8) will flow to the selected work tool. Relief valve (12) maintains the pressure for the pilot oil system. Refer to the Systems Operation, "Pilot Hydraulic System" for additional information.
Hydraulic System with the Diverter Valve (If Equipped)
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| Illustration 3 | g01214000 |
Work Tool Hydraulic System (1) Auxiliary circuit (2) Accumulator (3) Hydraulic tank (4) Tilt cylinder group (5) Lift cylinders (6) Control circuit for the work tool (7) Gear pump (8) Piston pump (9) Control valve (work tool) (10) Ball valve (11) Return manifold (12) Relief valve (charge oil) (13) Pilot valve (work tool) (14) Diverter valve | |
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| Illustration 4 | g01068267 |
(14) Diverter valve | |
When the pilot valve (13) is moved to the RAISE position, the lift spool in control valve (9) is shifted to the RAISE position by pilot oil. Hydraulic oil flows from the piston pump (8) through the lift spool and into the line for the head end of the lift cylinders (5). The oil from the rod end of the lift cylinders flows to the diverter valve (14). The pressure from the rod end of the lift cylinders is balanced with the pressure from the head end of the tilt cylinders. This causes the work tool to remain level while the lift arms are raised. From the diverter valve, the oil flows to the lift spool. The oil then flows out of the control valve (9) and back to the tank (3) .
The diverter valve only affects the RAISE function. The LOWER function is not affected by the diverter valve. In the LOWER position, oil flows from the spool to the diverter valve. From the diverter valve, the oil flows to the rod end of the cylinders. The oil pushes on the piston. The cylinders retract. Oil from the head end of the cylinders flows to the lift spool. The oil then flows out of the control valve (9) and back to the tank (3) .
For information on the operation of the diverter valve, refer to the Systems Operation, "Diverter Valve".
The ball valve (10) is used for manual lowering of the lift arms. The ball valve allows oil to drain out of the head end of the lift cylinders. The hydraulic oil flow is directed to the return manifold (11). The ball valve should be used to lower the lift arms when the engine fails.
Hydraulic System Without the Diverter Valve
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| Illustration 5 | g01068266 |
(10) Manual lowering valve | |
Note: Refer to Illustration 1 for reference.
When the control lever for the work tool is moved to the RAISE position, pilot oil flows to the left side of the lift spool that is part of the control valve (9). The pilot oil causes the lift spool to shift to the right.
Hydraulic oil flows from piston pump (8) into control valve (9). The oil then flows past the lift spool and into the line for the head end of the lift cylinders (5) .
As oil forces the rods of the lift cylinders to extend, oil is forced out of the rod end of the cylinders. The oil that flows from the rod ends of the cylinders flows to the lift spool. The oil then flows out of the control valve (9) and back to the tank (3) .
When the control lever for the work tool is moved to the LOWER position, pilot oil flows to the right side of the lift spool that is part of control valve (9). The pilot oil causes the lift spool to shift to the left. Hydraulic oil flows from piston pump (8) through the spool and into the line for the rod end of the lift cylinders.
As oil forces the rods to retract, the oil is forced out of the head end of the cylinders. The oil flows to the lift spool. The oil then flows out of the control valve (9) and back to the tank (3) .
When the control lever for the work tool is moved to the FLOAT position, pilot oil flows to the right side of the lift spool that is part of control valve (9). The pilot oil causes the lift spool to shift fully to the left. With the spool in this position, the spool opens the rod ends of both of the lift cylinders and the head ends of both of the lift cylinders to the hydraulic tank (3). The weight of the work tool will cause the work tool to lower to the ground. The work tool will then follow the contour of the ground. Supply oil from the piston pump (8) will continue to flow into control valve (9), but the supply oil will not flow to the lift cylinders (5). The tilt spool may be operated when the lift spool is in the FLOAT position.
In the event of engine failure, the ball valve (10) is used in order to manually lower the lift arms. Ball valve (10) allows oil to drain out of the head end of the lift cylinders. The hydraulic oil flow is directed to manifold (11) .
Hydraulic System for the Tilt Cylinders
Note: Refer to Illustration 3 for reference.
The hydraulic oil is directed to the tilt spool in the control valve (9) by the pilot valve (13). The end of the spool that receives the pilot oil depends on the position of the pilot valve (13) .
As the spool is shifted, hydraulic oil from the piston pump (8) flows through the tilt spool and into both of the tilt cylinders (4). Oil that leaves the tilt cylinders flows to the tilt spool. The oil then flows out of the control valve (9) and back to the tank (3) .
If the machine is equipped with a diverter valve (14), the tilt cylinders will also be connected to the diverter valve. The diverter valve acts as a load leveler. The diverter valve is used only when the lift cylinders are being raised.
For more information on the operation of the hydraulic system for the tilt cylinders, refer to the Systems Operation, "Control Valve (Work Tool)". For information on the operation of the diverter valve, refer to the Systems Operation, "Diverter Valve".
Auxiliary Hydraulic System
Note: Refer to Illustration 1 for reference.
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| Illustration 6 | g01068997 |
Control Valve (1) Auxiliary Couplings (1A) Couplings for circuit "A2" for the auxiliary (1B) Couplings for circuit "A1" for the auxiliary (6A) Coupling for circuit "C+" for the work tool control (6B) Coupling for circuit "C−" for the work tool control (6C) Coupling for case drain for the work tool control (9) Control Valve (15) Solenoid for circuit "A2" for the auxiliary (16) Solenoid for circuit "C+" for the work tool control (17) Solenoid valve (high flow) (18) Solenoid for circuit "C−" for the work tool control (19) Spool for the work tool control (20) Solenoid for circuit "A1" for the auxiliary (21) Spool for the auxiliary (A) Supply oil from the gear pump (B) Pilot supply oil for the TILT DOWN position of the tilt cylinders (C) Pilot supply oil for the RAISE position of the lift cylinders (D) Line to ball valve (E) Return to tank line (F) Pilot supply oil for the LOWER position of the lift cylinders (G) Load sensing oil line (H) Supply oil from piston pump (J) Return to tank line (K) Pilot supply oil for the TILT UP position of the tilt cylinders | |
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| Illustration 7 | g01068677 |
(22) Switch for the auxiliary | |
In order to activate the standard flow for the auxiliary circuit (1) or the control circuit for the work tool (6), you must press the right side of switch (22). The ECM for the auxiliary hydraulic circuit does not activate solenoid (17) in this mode. Solenoid (17) is in the position for standard flow.
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| Illustration 8 | g01068687 |
(13) Pilot valve ( work tool) (23) Thumb wheel for control of the auxiliary circuit (24) Button for the "C−" control circuit for the work tool (25) Button for the "C+" control circuit for the work tool | |
When you move the thumb wheel (23) that is located on the joystick, pilot oil is directed to the auxiliary circuit spool (21) that is located in the control valve (9). Thumb wheel (23) is a proportional switch. Move the thumb wheel slightly for a small amount of flow to the auxiliary. Move the thumb wheel farther in order to obtain full flow to the auxiliary.
Move the thumb wheel backward in order to increase the flow of oil to the "A1" coupling (1B). When you move the thumb wheel (23) backward, the ECM activates solenoid (20). Pilot oil from gear pump (7) moves through the energized solenoid in order to activate the spool (21). Supply oil from the piston pump (8) flows through the spool (21) to the "A1" coupling (1B). Oil from the piston pump flows through the work tool circuit and back through the "A2" coupling (1A) to the spool for the auxiliary (21). The oil then flows out of the control valve (9) and back to the tank (3) .
Move the thumb wheel forward in order to increase the flow of oil to the "A2" coupling (1A). When you move the thumb wheel (23) forward, the ECM activates solenoid (15). Pilot oil from gear pump (7) moves through the energized solenoid in order to activate the spool (21). Supply oil from the piston pump (8) flows through the spool (21) to the "A2" coupling (1A). Oil from the piston pump flows through the work tool circuit and back through the "A1" coupling (1B) to the spool for the auxiliary (21). The oil then flows out of the control valve (9) and back to the tank (3) .
Button (25) on the joystick controls the "C+" circuit for the work tool control. When you press button (25), the "C+" relay is energized. The relay supplies power to the "C+" solenoid (16). Pilot oil from gear pump (7) moves through the energized solenoid in order to activate the spool (19). Supply oil from the piston pump (8) flows through the spool (19) to the "C+" coupling (6A). Oil from the piston pump flows through the control circuit for the work tool and back through the "C−" coupling (6B) to the spool (19). The oil then flows out of the control valve (9) and back to the tank (3) .
Button (24) on the joystick controls the "C−" circuit for the work tool control. When you press button (24), the "C-" relay is energized. The relay supplies power to the "C-" solenoid (18). Pilot oil from gear pump (7) moves through the energized solenoid in order to activate the spool (19). Supply oil from the piston pump (8) flows through the spool (19) to the "C−" coupling (6B). Oil from the piston pump flows through the control circuit for the work tool and back through the "C+" coupling (6A) to the spool (19). The oil then flows out of the control valve (9) and back to the tank (3) .
For more information on the operation of the hydraulic system for the auxiliary, refer to the Systems Operation, "Control Valve (Work Tool)".
High Flow
Note: Refer to Illustrations 1, 6, and 7 for reference.
In order to activate the high flow for the auxiliary hydraulics, you must press the left side of switch (22). The ECM for the auxiliary hydraulic circuit activates solenoid (17). Solenoid (17) shifts to the right. When the solenoid shifts to the position for high flow, the pressure will increase in the line for load sensing (G). This will cause the piston pump (8) to increase the flow of oil to supply line (H) to the work tools.