Control Valve (Lift)
HOLD Position
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| Illustration 1 | g00607332 |
(1) Inlet to the valve bank. (2) Lift spool. (3) Control valve (lift). (4) Spring. (5) Spring. (6) Oil passage. (A) Port for the head end of the lift cylinders. (B) Port for the rod end of the lift cylinders. (C) Pilot oil for raising the work tool. (D) Pilot oil for lowering the work tool. | |
When the joystick control is in the HOLD position, the oil flows from the inlet (1) of the valve bank into the control valve (lift) (3). The oil flows around the spool (2) and through the passage (6) .
The flow of oil into ports (A) and (B) is blocked by the spool. The springs (4) and (5) hold the spool in place when no pilot oil is routed to the control valve (lift). No movement in the lift cylinders should occur.
RAISE Position
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| Illustration 2 | g00607535 |
(2) Lift spool. (3) Control valve (lift). (5) Spring. (7) Oil passage. (8) Bridge passage. (9) Load check valve. (10) Central passage. (11) Parallel passage. (12) Internal oil passage. (13) Supply passages for next valve. (A) Port for the head end of the lift cylinders. (B) Port for the rod end of the lift cylinders. (C) Pilot oil for raising the work tool. | |
When the joystick control is moved to the RAISE position, pilot oil (C) flows from the joystick control to the control valve (lift) (3) .
The pilot oil forces the spring (5) to compress and the pilot oil shifts the lift spool (2) to the left. Supply oil from central passage (10) is blocked by the spool (2). The oil will not be able to flow to the supply passages (13). As the oil pressure in the central passage increases the oil opens the load check valve (9) and the oil enters the bridge passage (8). Oil in the bridge passage flows around the spool and out of port (A). From port (A), the oil flows to the head end of the lift cylinders. Oil from the rod end of the lift cylinders enters the valve at port (B). Then, the oil flows into the internal passage (12) of the lift spool. From the internal passage, the oil flows to one of the supply passages and to the parallel passage (11). If the control valve (tilt) or the control valve (auxiliary) are not being operated, this oil flows through all of the central passages to the tank. If another control valve is operated, the central passages in the corresponding valve stop the oil from going to the tank. This oil is used to operate the other function.
When the joystick control is released from the RAISE position, the pilot oil stops flowing to the control valve (lift) and the spring shifts the spool back to the HOLD position.
LOWER Position
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| Illustration 3 | g00607537 |
(2) Lift spool. (3) Control valve (lift). (5) Spring. (8) Bridge passage. (9) Load check valve. (10) Central passage. (13) Supply passages for next valve. (14) Oil passage. (15) Spring retainer. (16) Internal passage. (A) Port for the head end of the lift cylinders. (B) Port for the rod end of the lift cylinders. (D) Pilot oil for lowering the work tool. | |
When the joystick control is moved to the LOWER position, pilot oil (D) flows from the joystick control to the control valve (lift) (3) .
The pilot oil forces the spring (5) to compress and the pilot oil shifts the lift spool (2) to the right until the spool contacts the spring retainer (15). Supply oil from central passage (10) is blocked by the spool (2). The oil will not be able to flow to the supply passages (13). As the oil pressure in the central passage increases, the oil opens the load check valve (9). This allows oil to flow to the bridge passage (8). Oil in the bridge passage flows out of port (B) to the rod end of the lift cylinders. Oil from the head end of the lift cylinders flows into port (A) and into the internal passage (16). This return oil acts on the internal check valve in the spool. The check valve shifts to the left and the oil flows around the check valve to a hole in the spool. Then, the oil flows out of the supply passage to the remaining valves. If the control valve (tilt) or the control valve (auxiliary) are not being operated, the oil flows through all of the central passages to the tank. If another valve is operated, the central passages in the corresponding valve stop the oil from going to the tank. This oil is used to operate the other function.
The internal check valve creates back pressure on the return oil. This helps to prevent cavitation in the cylinder.
When the joystick control is released from the LOWER position, the pilot oil stops flowing to the control valve (lift). Then, the spring shifts the spool back to the HOLD position.
FLOAT Position
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| Illustration 4 | g00607538 |
(2) Lift spool. (3) Control valve (lift). (4) Spring. (5) Spring. (8) Bridge passage. (9) Load check valve. (10) Central passage. (13) Supply passages for next valve. (14) Oil passage. (15) Spring retainer. (A) Port for the head end of the lift cylinders. (B) Port for the rod end of the lift cylinders. (D) Pilot oil for lowering the work tool. | |
When the joystick control is moved to the FLOAT position, pilot oil (D) flows from the joystick control to the control valve (lift) (3). The joystick control is detented in the FLOAT position. The joystick control stays in the FLOAT position until the joystick control is pulled out of the detent.
The pilot oil forces the spring (5) to compress and the pilot oil shifts the lift spool (2) to the right. When the lift spool contacts the spring retainer (15), the pilot oil continues to shift the lift spool until the retainer contacts the seat. Supply oil from central passage (10) is not blocked from entering the supply passages (13). Lands on the spool also block the oil in the bridge passage (8). The load check valve (9) will remain seated. The spool (2) opens ports (A) and (B) to the tank through passages (14) and (17). When both ends of the cylinders are open to the tank, the weight of the lift arms and of the work tool causes the work tool to lower to the ground.
When the control valve (lift) is in the FLOAT position, the work tool follows along the contour of the ground.
When the joystick control is taken out of the FLOAT position, the pilot oil stops flowing to the control valve (lift) and the springs will move the spool back to the HOLD position.
Control Valve (Tilt)
HOLD Position
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| Illustration 5 | g00607351 |
(3) Control valve (lift). (18) Control valve (tilt). (19) Tilt spool. (20) Spring. (21) Spring. (22) Oil passage. (A) Port for the head end of the tilt cylinders. (B) Port for the rod end of the tilt cylinders. (E) Pilot oil for tilting the work tool forward. (F) Pilot oil for tilting back the work tool. | |
When the joystick control is in the HOLD position, the oil flows from the control valve (lift) (3) into the control valve (tilt) (18). Oil flows around the tilt spool (19) and through the passage (22) in the control valve (tilt).
The flow of oil into ports (A) and (B) is blocked by the spool. The springs (20) and (21) hold the spool in place when no pilot oil is routed to the tilt control valve. No movement in the tilt cylinders should occur.
TILT FORWARD Position
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| Illustration 6 | g00607575 |
(18) Control valve (tilt). (19) Tilt spool. (20) Spring. (22) Supply passage for the next valve. (23) Bridge passage. (24) Oil passage. (25) Oil passage. (26) Central passages. (A) Port for the head end of the tilt cylinders. (B) Port for the rod end of the tilt cylinders. (E) Pilot oil for tilting the work tool forward. | |
When the joystick control is moved to the TILT FORWARD position, pilot oil (E) flows from the joystick control to the control valve (tilt) (18) .
The pilot oil forces the spring (20) to compress and the pilot oil shifts the tilt spool (19) to the right. Supply oil from the central passages (26) is blocked by the spool (17). The oil will not be able to flow to the supply passage (22). Oil pressure in the parallel passage (11) increases. This causes the load check valve (9) to open. The oil enters the bridge passage (23). Oil in the bridge passage flows past the spool and out port (A) to the head ends of the tilt cylinders. Oil from the rod ends of the tilt cylinders flows into port (B) and the oil is blocked from flowing to the tank. This oil is added to the supply oil that flows to port (A). This prevents cavitation of the cylinder. The added oil also provides a powered tilt function.
When the joystick control is released from the TILT FORWARD position, the pilot oil stops flowing to the control valve (tilt) and the spring shifts the spool back to the HOLD position.
TILT BACK Position
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| Illustration 7 | g00607576 |
(18) Control valve (tilt). (19) Tilt spool. (21) Spring. (22) Supply passage for the next valve. (23) Bridge passage. (26) Central passages. (27) Oil passage. (28) Oil passage. (29) Return oil passage. (A) Port for the head end of the tilt cylinders. (B) Port for the rod end of the tilt cylinders. (F) Pilot oil for tilting back the work tool. | |
Supply oil from the central passages (26) is blocked from entering the supply passage (22). Oil pressure in the parallel passage (11) increases and the oil opens the load check valve (9). The oil then enters the bridge passage (23). Oil in the bridge passage flows through passage (27) and out of port (B) to the rod ends of the tilt cylinders. Oil from the head ends of the tilt cylinders enters port (A) and flows through passage (28) to the return passage (29) .
When the joystick control is released from the TILT BACK position, the pilot oil stops flowing to the control valve (tilt) and the spring shifts the spool back to the HOLD position.
Control Valve (Auxiliary) (if equipped)
HOLD Position
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| Illustration 8 | g00607352 |
(18) Control valve (tilt). (30) Control valve (auxiliary). (31) Spring. (32) Spring. (33) Auxiliary circuit spool. (34) Oil passage. (A) Port for the female auxiliary connector. (B) Port for the male auxiliary connector. (G) Pilot oil for Position 1. (H) Pilot oil for Position 2. | |
When the auxiliary circuit control switch is in the OFF position, the oil flows from the control valve (tilt) (18) into the control valve (auxiliary) (30). Oil flows around the auxiliary spool (33) and through the central passage (34) in the control valve.
The flow of the oil into ports (A) and (B) is blocked by the spool. The springs hold the auxiliary circuit spool in place when no pilot oil is routed to control valve (auxiliary). No movement in the auxiliary circuit should occur.
Position One
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| Illustration 9 | g00607577 |
(9) Load check valve. (11) Parallel passage. (30) Control valve (auxiliary). (31) Spring. (33) Auxiliary circuit spool. (35) Oil passage. (36) Bridge passage. (37) Passage that returns to the tank. (38) Oil passage. (39) Return passage. (40) Central passages. (A) Port for the female auxiliary connector. (B) Port for the male auxiliary connector. (G) Pilot oil for moving the auxiliary circuit spool to Position 1. | |
When the left side of the auxiliary circuit control switch is pressed, pilot oil (G) forces the spring (31) to compress. This shifts the auxiliary circuit spool (33) to the right. Supply oil from the central passages (40) is blocked from entering the supply passage (37). Oil pressure in the parallel passage (11) increases and the oil opens the load check valve (9). The oil then enters the bridge passage (36). Oil in the bridge passage flows through passage (35) and out port (A) to the female auxiliary connector. Return oil flows into port (B) and through passage (38) to the return passage (39) .
When the auxiliary circuit control switch is released, the pilot oil stops flowing to the control valve (auxiliary) (30) and the spring returns the auxiliary spool to the HOLD position.
Position Two
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| Illustration 10 | g00607578 |
(9) Load check valve. (11) Parallel passage. (30) Control valve (auxiliary). (32) Spring. (33) Auxiliary circuit spool. (35) Oil passage. (36) Bridge passage. (37) Passage that returns to the tank. (38) Oil passage. (39) Return passage. (40) Central passages. (A) Port for the female auxiliary connector. (B) Port for the male auxiliary connector. (H) Pilot oil for moving the auxiliary circuit spool to Position 2. | |
When the right side of the auxiliary circuit control switch is pressed, pilot oil (H) forces the spring (32) to compress. This shifts the auxiliary circuit spool (33) to the left. Supply oil from the central passages (40) is blocked from entering the supply passage (37). Oil pressure in the parallel passage (11) increases and the oil opens the load check valve (9). The oil then enters the bridge passage (36). Oil in the bridge passage flows through passage (38) and out port (B) to the male auxiliary connector. Return oil flows into port (A) and through passage (35) to the return passage (39) .
When the auxiliary circuit control switch is released, the pilot oil stops flowing to the control valve (auxiliary) (30) and the spring returns the auxiliary circuit spool to the HOLD position.