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| Illustration 1 | g01430988 |
Schematic for the hydraulic system (1) Auxiliary control valve (2) Line relief valve for rod end of auxiliary cylinder (3) Line relief valve for head end of auxiliary cylinder (4) Auxiliary cylinder (5) Line relief valve for rod end of tilt cylinder (6) Line relief valve for head end of tilt cylinder (7) Pressure tap for rod end of tilt cylinder (8) Pressure tap for head end of tilt cylinder (9) Tilt cylinder (10) Ride control accumulator (11) Ride control solenoid valve (12) Lift cylinders (13) Makeup valve (14) Main control valve (15) Lift circuit relief valve (16) Pilot control valve (17) Main relief valve (18) Pilot diverter solenoid valve (19) Pilot diverter solenoid valve (20) Lift arm positioner valve (21) Float sequence valve (22) Ride control solenoid valve (23) Check valve (24) Line for steering and bucket control valve - remote control (25) Implement and steering solenoid valve (26) Selector and pressure control valve (27) Line to steering control valve (28) Pressure tap for the parking brake system (29) Check valve (30) Pressure tap for the main hydraulic system (31) Check valve (32) Parking brake oil pressure switch (33) Breaker relief valve (34) Portable hydraulic pump quick connect coupler (35) Pilot oil pressure reducing valve (36) Return line from the brake accumulator charging valve (37) Automatic lubrication system connection port (38) Line to brake release sequence valve (39) Pilot and braking pump (40) Steering pump (41) Implement pump (42) Automatic lubrication system connection port (43) Hydraulic oil filters (44) Hydraulic tank (45) Portable hydraulic pump quick connect coupler (46) Line for the brake accumulator charging valve (47) Parking brake control valve (48) Pressure tap for the pilot circuit (49) Line for parking brake | |
Hold Position
When the engine is running with the joystick control lever in the HOLD position, pilot and braking pump (39) draws oil from hydraulic tank (44) and directs pressure oil through check valve (29) to pilot oil pressure reducing valve (35). Pilot oil pressure reducing valve (35) maintains a constant oil pressure in the pilot system. The pilot pressure oil flows through check valve (31), implement and steering solenoid valve (25) and pilot control valve (16). The valve spools in pilot control valve (16) stop the flow of oil. Excess oil flows from pilot oil pressure reducing valve (35) to hydraulic tank (44) .
At the same time, implement pump (41) sends oil to main relief valve (17) which controls the maximum oil pressure in the implement circuit.
With both valve spools of main control valve (14) in the HOLD position, oil flows through main control valve (14) and returns to hydraulic tank (44) via hydraulic oil filters (43). If oil filters (43) become full of foreign material (debris), the filter bypass valve will open and let return oil flow directly to hydraulic tank (44) .
Tilt Circuit
Line relief valves (5) and (6) protect tilt cylinder (9) from external shocks when the tilt control valve spool is in the HOLD position. When the pressure in the tilt cylinder exceeds the setting of either line relief valve, the line relief valves open to vent the excess pressure to hydraulic tank (44). This prevents damage to the machine components.
TILT BACK Operation
When the engine is running with the joystick control lever in the TILT BACK position, pilot pressure oil flows through pilot control valve (16) to the tilt back end of the tilt control valve spool. This causes the tilt control valve spool to move. The pilot oil at the dump end of the tilt control valve spool flows to pilot control valve (16) and returns to hydraulic tank (44) .
With the movement of main control valve (14) to the TILT BACK position, oil through main control valve (14) is stopped. Implement pump oil pressure increases and opens the load check valve. The pressure oil from implement pump (41) now flows to the head end of tilt cylinder (9) causing the cylinder rod to extend.
The movement of the tilt cylinder piston and rod pushes oil out of the rod end of the tilt cylinder. This oil flows to main control valve (14) and returns to hydraulic tank (44) .
When the joystick control lever is released, pilot control valve (16) returns to the HOLD position causing the flow of pilot pressure oil to stop. The springs on the tilt control valve spool move the tilt valve spool back to the HOLD position.
The implement oil in tilt cylinder (9) is trapped by the tilt control valve spool and movement of the tilt cylinder piston and rod stops. The bucket will stay in this position until pilot control valve (16) is moved again.
DUMP Operation
When the engine is running with the joystick control lever in the DUMP position, pilot pressure oil flows through pilot control valve (16) to the dump end of the tilt control valve spool. This causes the tilt control valve spool to move. The pilot oil at the tilt back end of the tilt control valve spool flows to pilot control valve (16) and returns to hydraulic tank (44) .
With the movement of main control valve (14) to the DUMP position, oil through main control valve (14) is stopped. Implement pump oil pressure increases and opens the load check valve. The pressure oil from implement pump (41) now flows to the rod end of tilt cylinder (9) causing the tilt cylinder rod to retract.
The movement of the tilt cylinder piston and rod pushes oil out of the head end of the tilt cylinder. This oil flows to main control valve (14) and returns to hydraulic tank (44) .
When the joystick control lever is released, pilot control valve (16) returns to the HOLD position causing the flow of pilot pressure oil to stop. The springs on the tilt control valve spool move the tilt valve spool back to the HOLD position.
The implement oil in tilt cylinder (9) is trapped by the tilt control valve spool and movement of the tilt cylinder piston and rod stops. The bucket is held in this position until pilot control valve (16) is moved again.
DUMP Operation with engine stopped
When the lift arms are raised, the bucket can be dumped with the engine stopped. The pilot oil supply comes from the head end of the lift cylinders. This oil flows through check valve (23) to selector and pressure control valve (26) which decreases the pressure of the oil to pilot oil pressure. The oil flows to implement and steering solenoid valve (25) and then to pilot control valve (16) .
When pilot control valve (16) is moved to the DUMP position, the oil flows to the tilt control valve spool moving it to the DUMP position. The head end of tilt cylinder (9) is now open to hydraulic tank (44). The makeup valve in main control valve (14) opens so that the rod end of tilt cylinder (9) is also open to hydraulic tank (44). The weight of the bucket causes the bucket to dump.
Note: When the engine is stopped and the lift arms are raised, the bucket can also be lowered.
Lift Circuit
Lift circuit relief valve (15) protects lift cylinders (12) from external shocks when the lift control valve spool is in the HOLD position. When the pressure in lift cylinders (12) exceeds the setting of lift circuit relief valve (15), the relief valve opens allowing high pressure oil to return to hydraulic tank (44). This prevents damage to the machine components.
RAISE Operation
When the engine is running with the joystick control lever in the RAISE position, pilot pressure oil flows through pilot control valve (16) to the raise end of the lift control valve spool. This causes the lift control valve spool to move. The pilot oil at the lower end of the lift control valve spool flows to pilot control valve (16) and returns to hydraulic tank (44) .
With the movement of main control valve (14) to the RAISE position, oil through main control valve (14) is stopped. Implement pump oil pressure increases and opens the load check valve. The pressure oil from implement pump (41) now flows to the head end of lift cylinders (12) causing the cylinder rods to extend.
The movement of lift cylinder pistons and rods, pushes oil out of the rod end of the lift cylinders. This oil flows to main control valve (14) and returns to hydraulic tank (44) .
When the joystick control lever is released, pilot control valve (16) returns to the HOLD position causing the flow of pilot pressure oil to stop. The springs on the lift control valve spool moves the valve spool to the HOLD position.
The implement oil in lift cylinders (12) is trapped by the lift control valve spool and movement of the cylinder pistons and rods stop. The lift arms are held in this position until pilot control valve (16) is moved again.
LOWER Operation
When the engine is running with the joystick control lever in the LOWER position, pilot pressure oil flows through pilot control valve (16) to the lower end of the lift control valve spool. This causes the lift control valve spool to move. The pilot oil at the raise end of the lift control valve spool flows to pilot control valve (16) and returns to hydraulic tank (44) .
With the movement of main control valve (14) to the LOWER position, oil through main control valve (14) is stopped. Implement pump pressure increases and opens the load check valve. The pressure oil from implement pump (40) now flows to the rod end of lift cylinders (12) and causes the cylinder rods to retract.
The movement of the lift cylinder pistons and rods pushes the oil out of the head end of the lift cylinders. This oil flows into main control valve (14) and returns to hydraulic tank (44) .
When the joystick control lever is released, pilot control valve (16) returns to the HOLD position causing the flow of pilot pressure oil to stop. The springs on the lift control valve spool move the valve spool back to the HOLD position.
The implement oil in lift cylinders (12) is trapped by the lift control valve spool and movement of the lift cylinder pistons and rods stop. The lift arms are held in this position until pilot control valve (16) is moved again.
FLOAT Operation
When the joystick control lever is moved through the LOWER position and in to the FLOAT position, pilot pressure oil flows through pilot control valve (16) to the lower end of the lift control valve. The extra movement of the joystick control lever, allows greater pilot pressure oil into the lower end of the lift control valve spool. This pressure is also felt in float sequence valve (21). This pressure moves the spool in float sequence valve (21), which allows oil in the spring chamber of makeup valve (13) to vent (drain) to hydraulic tank (44). This permits makeup valve (13) to open and lets implement oil flow directly to hydraulic tank (44). The head end and rod end of lift cylinders (12) are now open to hydraulic tank (44). Outside forces on the bucket will control the movement of the cylinder pistons and rods.
When the joystick control lever is released it will return to the HOLD position.
LOWER Operation with engine stopped
The bucket can be lowered with the engine stopped. The pilot oil supply comes from the head end of the lift cylinders. This oil flows through check valve (23) to selector and pressure control valve (26) which decreases the pressure of the oil to pilot oil pressure. The oil flows to implement and steering solenoid valve (25) and then flows to pilot control valve (16) .
When the joystick control lever is moved through the LOWER position and in to the FLOAT position, pilot pressure oil flows through pilot control valve (16) to the lower end of the lift control valve. The extra movement of the joystick control lever, allows greater pilot pressure oil into the lower end of the lift control valve spool. This pressure is also felt in float sequence valve (21). This pressure moves the spool in float sequence valve (21), which allows oil in the spring chamber of makeup valve (13) to vent (drain) to hydraulic tank (44). This permits makeup valve (13) to open and lets implement oil flow directly to hydraulic tank (44). The head end and rod end of lift cylinders (12) are now open to hydraulic tank (44). Outside forces on the bucket will control the movement of the cylinder pistons and rods.
Note: When the engine is stopped and the lift arms are raised, the bucket can also be dumped.
Auxiliary Circuit
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| Illustration 2 | g01262739 |
Location of the switch to activate the auxiliary system | |
The flow of oil from implement pump (41) changes when the machine has the auxiliary system. The implement oil now flows first to the auxiliary control valve spool before it flows to the tilt control valve spool and the lift control valve spool.
Auxiliary line relief valves (2) and (3) protect auxiliary cylinders (4) from external shocks. When the pressure in the auxiliary cylinders exceed the setting of either auxiliary line relief valve, the relief valves open to vent the excess pressure to hydraulic tank (44) .
EJECT Operation
When the engine is running, press and hold the switch to activate the auxiliary system. Move the joystick control lever to the EJECT position. Pilot pressure oil flows through pilot diverter solenoid valve (18) to the eject end of the auxiliary control valve spool. This causes the auxiliary control valve spool to move. The pilot oil at the retract end of the auxiliary control valve spool flows through pilot diverter solenoid valve (19), pilot control valve (16) and returns to hydraulic tank (44) .
The movement of the auxiliary control valve spool stops the flow of oil through auxiliary control valve (1). Implement pump oil pressure increases and opens the load check valve. The oil from implement pump (41) now flows to the head end of auxiliary cylinders (4) and causes the cylinder rods to extend.
RETRACT Operation
When the engine is running, press and hold the switch to activate the auxiliary system. Move the joystick control lever to the RETRACT position. Pilot pressure oil flows through pilot diverter solenoid valve (19) to the retract end of the auxiliary control valve spool. This causes the auxiliary control valve spool to move. The pilot oil at the eject end of the auxiliary control valve spool flows through pilot diverter solenoid valve (18), pilot control valve (16) and returns to hydraulic tank (44) .
The movement of the auxiliary control valve spool stops the flow of oil through auxiliary control valve (1). Implement pump oil pressure increases and opens the load check valve. The oil from implement pump (41) now flows to the rod end of auxiliary cylinders (4) and causes the cylinder rods to retract.