HOLD Position
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| Illustration 1 | g00875310 |
HOLD position for the extendable stick control valve (1) Control spool, (2) Passage to tank, (3) Signal passage, (4) Chamber, (5) Flow control valve, (6) Passage, (7) Pump passage, (8) Passage, (9) Hole, (10) Spring, (11) Chamber, (12) Signal passage, (13) Passage to tank, (14) Spring, (15) Line to the next valve, (16) Secondary resolver, (17) Line from the previous valve, (18) Primary resolver, (19) Spring, (20) Line Relief Valve, (21) Lock valve, (22) Port to rod end of the extendable stick cylinder, (23) Passage, (24) Extendable Stick Cylinder, (25) Piston, (26) Passage, (27) Port to head end of the extendable stick cylinder, (28) Lock Valve, (29) Spring, (30) Line Relief and Makeup Valve, (A) Pump oil, (B) Return oil and (C) Blocked oil | |
The control valve for the extendable stick is located between the control valve for the boom and the end cover.
In the HOLD position, spool (1) is centered by spring (14). The oil in the head end of the extendable stick cylinder is blocked at lock valve (28). The oil in the rod end of the extendable stick cylinder is blocked at lock valve (21). Lock valve (21) and lock valve (28) are used to prevent cylinder drift. Passage (3) is open to the tank through passage (2). Passage (12) is open to the tank through passage (13). The return to the tank passage is common in all control valves.
Chamber (11) is connected to the primary resolver (18). Chamber (11) is open to the tank through passages (3) and (12) which are connected to the primary resolver (17) in the HOLD position.
The oil from the pump enters the passage (7). Passage (7) is common in all sections of the valves and the passage has no outlet. Oil flows into passage (6) through hole (9) in flow control valve (5). The oil then flows into chamber (4) .
Pressure in chamber (4) rises and the pressure acts against flow control valve (5). When the pressure overcomes the force of the spring (10), the pressure causes flow control valve (5) to move to the left. As flow control valve (5) moves to the left, oil flows from passage (7) into passage (8). The oil in passage (8) is blocked by spool (1) until the operator moves the control pedal.
As the flow control valve (5) moves to the left, the metering slots begin to close. The oil that flows from passage (7) to passage (8) is restricted. Oil is now metered through the slots in order to maintain pressure in chamber (4) and passage (8) .
Retract Position
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| Illustration 2 | g00875311 |
Retract position for the Extendable stick control valve (1) Control spool, (2) Passage to tank, (3) Signal passage, (4) Chamber, (5) Flow control valve, (6) Passage, (7) Pump passage, (8) Passage, (9) Hole, (10) Spring, (11) Chamber, (12) Signal passage, (13) Passage to tank, (14) Spring, (15) Line to the next valve, (16) Secondary resolver, (17) Line from the previous valve, (18) Primary resolver, (19) Spring, (20) Line Relief Valve, (21) Lock valve, (22) Port to rod end of the extendable stick cylinder, (23) Passage, (24) Extendable Stick Cylinder, (25) Piston, (26) Passage, (27) Port to head end of the extendable stick cylinder, (28) Lock Valve, (29) Spring, (30) Line Relief and Makeup Valve, (A) Pump oil, (B) Return oil and (C) Blocked oil | |
When the operator pushes on the heel end of the foot pedal, spool (1) moves to the right.
Pump oil from passage (8) flows around spool (1) and into passage (23). Then oil flows to lock valve (21) and spool (25). Oil in signal passage (12) is blocked from entering the passage to the tank (13). Oil in signal passage (12) senses the pressure in port (23). The oil in signal passage (12) flows to the primary resolver (18) and into chamber (11) .
The oil in the primary resolver (17) flows to the secondary resolver (16) and to the pump. This causes the pump to increase flow.
Flow control valve (5) compares the oil in chamber (4) to the signal pressure in chamber (11) and spring (10). Flow control valve (5) moves in order to provide the required oil flow to passage (8). Spool (1) controls the amount of flow that is desired.
As pump flow increases, flow control valve (5) moves in order to allow more oil to flow past spool (1) to passage (23) .
When the pressure in passage (23) overcomes the force of spring (19), lock valve (21) will move to the left and spool (25) will move to the right. As spool (25) moves to the right, lock valve (28) will move to the right. Then, the oil flows to the rod end of extendable stick cylinder through port (22). This causes the extendable stick to retract.
As the extendable stick retracts, the oil flows from the head end of the extendable stick cylinder into port (27) and through lock valve (28). The oil flows from lock valve (28) through passage (26) and into signal passage (3). The oil flows from passage (3) into passage (2) to the hydraulic tank.
If the pump supply pressure becomes less than the requirements for the work port, the flow control valve (5) will move to the right in order to maintain pressure in port (8) .
When the operator releases the control pedal, spring (14) will return spool (1) to the HOLD position.
EXTEND Position
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| Illustration 3 | g00875312 |
Extend position for the extendable stick cylinder (1) Control spool, (2) Passage to tank, (3) Signal passage, (4) Chamber, (5) Flow control valve, (6) Passage, (7) Pump passage, (8) Passage, (9) Hole, (10) Spring, (11) Signal passage, (12) Signal passage, (13) Passage to tank, (14) Spring, (15) Line to the next valve, (16) Secondary resolver, (17) Line from the previous valve, (18) Primary resolver, (19) Spring, (20) Line Relief Valve, (21) Lock valve, (22) Port to rod end of the extendable stick cylinder, (23) Passage, (24) Extendable Stick Cylinder, (25) Piston, (26) Passage, (27) Port to head end of the extendable stick cylinder, (28) Lock Valve, (29) Spring, (30) Line Relief and Makeup Valve, (A) Pump oil, (B) Return oil and (C) Blocked oil | |
When the operator pushes on the toe end of the control pedal, spool (1) moves to the left.
Pump oil from passage (8) flows around spool (1) and into passage (26). Then oil flows to lock valve (28) and spool (25). Oil in signal passage (3) is blocked from entering the passage to the tank (2). Oil in signal passage (3) senses the pressure in port (26). The oil in signal passage (3) flows to the primary resolver (18) and into chamber (11) .
The oil in the primary resolver (17) flows to the secondary resolver (16) and to the pump. This causes the pump to increase flow.
Flow control valve (5) compares the oil in chamber (4) to the signal pressure in chamber (11) and spring (10). Flow control valve (5) moves in order to provide the required oil flow to passage (8). Spool (1) controls the amount of flow that is desired.
As pump flow increases, flow control valve (5) moves in order to allow more oil to flow past spool (1) to passage (26) .
When the pressure in passage (26) overcomes the force of springs (19) and (29), lock valve (28) will move to the right and spool (25) will move to the left. As spool (25) moves to the left, lock valve (21) will move to the left. Then, the oil flows to the head end of extendable stick cylinder through port (27). This causes the extendable stick to extend.
As the extendable stick extends, the oil flows from the rod end of the extendable stick cylinder into port (22) and through lock valve (21). The oil flows from lock valve (21) through passage (23) and into signal passage (12). The oil flows from passage (12) and into passage (13) to the hydraulic tank.
When the operator releases the control pedal, spring (14) will return spool (1) to the HOLD position.
Refer to Systems Operation, "Makeup and Relief Valve" for the operation of valve (30) .
Operation of Work Tool (If Equipped)
When a work tool is attached to the end of the stick, the hydraulic hoses for the work tool are connected to the auxiliary hoses on the stick.
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| Illustration 4 | g00291493 |
When the work tool is operated, the extendable stick should be pinned into the retract position.
The work tool is operated by depressing the extendable stick control pedal. Refer to the Operation and Maintenance Manual for the proper controls that are used in order to operate the work tools.