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| Illustration 1 | g01455971 |
Work Tool Hydraulic System (1) Quick disconnects for the auxiliary circuit (2) Accumulator (3) Hydraulic Tank Group (4) Tilt Cylinder Group (5) Lift Cylinders (6) Gear Pump (charge oil, work tool, air conditioner and fan drive) (7) Control Valve (work tool) (8) Return Manifold Group (9) Ball Valve (10) Pilot Valve (work tool) (11) Relief Valve (charge oil) | |
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| Illustration 2 | g01045590 |
(3) Hydraulic Tank Group (6) Gear Pump (charge oil, work tool, air conditioner and fan drive) (7) Control Valve (work tool) | |
Gear pump (6) supplies the work tool hydraulic system with oil. Pump (6) is mounted to the front end of the piston pump for the hydrostatic system. Pump (6) is splined to the drive shaft of the piston pump for the hydrostatic system. The piston pump for the hydrostatic system is mounted to the engine. When the engine speed increases, the speed of pump (6) increases. This causes pump (6) to pump more oil to the work tool hydraulic system.
The rear section of gear pump (6) continuously pumps oil through control valve (7). Control valve (7) is an open center control valve. The oil pressure for control valve (7) is regulated by a main relief valve that is installed in control valve (7) .
The pilot oil for the work tool hydraulic system is supplied by the front section of pump (6). Oil flows out of the front section of pump (6) 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 (10), all three of the interlocks must be disengaged. In order for oil to flow to pilot valve (10), the hydraulic enable solenoid must be energized.
When the electrical requirements are complete, pilot oil will flow through a check valve to the accumulator (2). The pilot oil is used to charge the accumulator (2). The pilot oil will also flow to the pilot valve (10). When pilot valve (10) is activated, oil will be directed to control valve (7) in order to shift a control spool to the desired position. Once a control spool shifts, high pressure oil from pump (6) will flow to the selected work tool. Relief valve (11) maintains the pressure for the pilot oil system. Refer to the Systems Operation, "Pilot Hydraulic System" for additional information.
Hydraulic System for the Lift Arms Without the Diverter Valve (If Equipped)
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| Illustration 3 | g01455977 |
Work Tool Hydraulic System (1) Quick disconnects for the auxiliary circuit (2) Accumulator (3) Hydraulic Tank Group (4) Tilt Cylinder Group (5) Lift Cylinders (6) Gear Pump (charge oil, work tool, air conditioner and fan drive) (7) Control Valve (work tool) (8) Return Manifold (9) Ball Valve (10) Pilot Valve (work tool) (11) Relief Valve (charge oil) | |
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| Illustration 4 | g01455984 |
(7) Control Valve (work tool) (9) Ball Valve | |
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 (7). The pilot oil causes the lift spool to shift to the right.
Hydraulic oil flows from gear pump (6) into control valve (7). 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 to the tilt spool that is part of control valve (7) .
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 (7). The pilot oil causes the lift spool to shift to the left. Hydraulic oil flows from gear pump (6) 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 to the tilt spool that is part of control valve (7) .
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 (7). 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 gear pump will continue to flow into control valve (7). The tilt spool may be operated when the lift spool is in the FLOAT position.
In the event of engine failure, the ball valve (9) is used in order to manually lower the lift arms. Ball valve (9) allows oil to drain out of the head end of the lift cylinders. The hydraulic oil flow is directed to manifold (8) .
Hydraulic System for the Lift Arms with the Diverter Valve (If Equipped)
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| Illustration 5 | g01455990 |
Work Tool Hydraulic System (1) Quick disconnects for the auxiliary circuit (2) Accumulator (3) Hydraulic Tank Group (4) Tilt Cylinder Group (5) Lift Cylinders (6) Gear Pump (charge oil, work tool, air conditioner and fan drive) (7) Control Valve (work tool) (8) Return Manifold (9) Ball Valve (10) Diverter Valve (11) Pilot Valve (work tool) | |
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| Illustration 6 | g01455996 |
(5) Lift Cylinders (7) Control Valve (work tool) (9) Ball Valve (10) Diverter Valve | |
When the pilot valve (11) is moved to the RAISE position, the lift spool in control valve (7) is shifted to the RAISE position by pilot oil. Hydraulic oil flows from the gear pump (6) through the lift spool and into the line for the head end of the lift cylinders (4). The oil from the rod end of the lift cylinders flows to the diverter valve (10). 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 to the tilt spool.
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. Then, the oil flows to the tilt spool.
For information on the operation of the diverter valve, refer to the Systems Operation, "Diverter Valve".
The ball valve (9) 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 (8). The ball valve should be used to lower the lift arms when the engine fails.
Tilt and Auxiliary Hydraulic System
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| Illustration 7 | g01456005 |
(1) Pilot valve ( work tool) (2) Ball valve ( manual work tool lowering) (3) Control valve ( work tool) (4) Lift cylinders (5) Tilt cylinders (6) Auxiliary couplings (7) Return manifold (8) Gear pump (9) Hydraulic tank | |
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| Illustration 8 | g01456020 |
(3) Control valve ( work tool) (5) Tilt cylinders (6) Auxiliary couplings | |
The hydraulic oil is directed to the tilt spool in the control valve (3) by the pilot valve (1). The end of the spool that receives the pilot oil depends on the position of the pilot valve (1) .
As the spool is shifted, hydraulic oil flows through the tilt spool and into both of the tilt cylinders.
If the machine is equipped with a diverter valve, 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.
Pilot oil is directed to the auxiliary circuit spool that is located in the control valve (3) by the auxiliary circuit switch. The auxiliary circuit switch is located on the pilot valve (1) .
The pilot oil for the auxiliary circuit does not flow through the pilot valve (1). When the auxiliary circuit switch is pressed, one of the modulating valves in the control valve (3) will shift. This causes the auxiliary circuit spool to shift. Oil can then flow from the gear pump (8) to auxiliary couplings (6) .
For more information on the operation of the tilt and auxiliary hydraulic system, refer to the Systems Operation, "Control Valve (Work Tool)".