HOLD Position
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| Illustration 1 | g01222520 |
Decking Blade Valve (1) Proportional solenoid (2) Check valve (3) Control spool (4) Passage to tank (5) Signal passage (6) Chamber (7) Port to head end of cylinders (8) Spool (9) Pump passage (10) Passage (11) Passage (12) Port to rod end of cylinders (13) Spring cavity (14) Signal port from resolver (15) Spring (16) Signal passage (17) Passage to tank (18) Springs (19) Proportional solenoid | |
The decking blade valve is located between the end cover and the steering control valve. Pump oil flows from the steering control valve into the decking blade valve through passage (9). Passage (9) is common in all valve sections and the passage has no outlet.
The control lever sends pilot oil to the solenoids (1) and (19) at either end of the decking blade valve. When the operator places the control lever in the HOLD position, solenoids (1) and (19) remain deactivated. Springs (18) keep spool (3) in the HOLD position.
Oil flows into passage (10) through openings in spool (8). Then, the oil flows into chamber (6) .
Pressure in chamber (6) rises, and the pressure acts against spool (8). The pressure overcomes the force of spring (15) and this causes spool (8) to move downward. As spool (8) moves downward, oil flows from passage (9) into passage (11). The oil in passage (11) is blocked by spool (3) .
As spool (8) moves downward, slots in the spool begin to close. When the slots close, oil flow from passage (9) to passage (11) is restricted. Oil flows from signal passage (16) into spring cavity (13) through port (14) .
Oil is now metered through the slots in spool (8) in order to maintain pressure in chamber (6) and passage (11) above the pressure in signal cavity (16). The pressure in signal cavity (16) is lower than the pump pressure in passage (9) .
In the HOLD position, spool (3) blocks the oil in passage (11) from flowing into either port (7) or port (12). The oil in the cylinder head end and in the lines is also blocked at port (7). At the same time, oil in the cylinder rod end and in the lines is blocked at port (12) .
Since no oil is flowing to the cylinders, oil in passages (4), (5), (14), (16), and (17) returns to the hydraulic tank.
Springs (18) hold spool (3) in the HOLD position.
RAISE Position
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| Illustration 2 | g01222520 |
Decking Blade Valve (1) Proportional solenoid (2) Check valve (3) Control spool (4) Passage to tank (5) Signal passage (6) Chamber (7) Port to head end of cylinders (8) Spool (9) Pump passage (10) Passage (11) Passage (12) Port to rod end of cylinders (13) Spring cavity (14) Signal port from resolver (15) Spring (16) Signal passage (17) Passage to tank (18) Springs (19) Proportional solenoid | |
When the operator places the control lever in the RAISE position, pilot oil activates solenoid (19). Spool (3) moves upward. Pump oil enters through passage (9). Oil flows into passage (10) through openings in spool (8). Then, the oil flows into chamber (6) .
Pressure in chamber (6) rises and the pressure acts against spool (8). The pressure overcomes the force of spring (15) and this causes spool (8) to move downward. As spool (8) moves downward, oil flows from passage (9) into passage (11) .
As spool (3) starts to move upward, oil flows past the spool into signal passage (16) and the oil flows back to the pump control. This causes the pump to upstroke.
When spool (3) moves up far enough, the oil flows from passage (11) past the spool into port (12). Most of this oil flows into the rod ends of the cylinders and this causes the rods to retract. When the rods retract, the blade will raise. The pressure is high enough to keep the blade from moving back down as the blade goes from the partial RAISE to the full RAISE position.
Some of the oil in port (12) flows into signal passage (16). As the cylinders retract, this will force the oil from the head ends of the cylinders. This oil flows into port (7), past spool (3), and into passages (4) and (5). Then, the oil flows from passage (4) back to the hydraulic tank.
In the RAISE position, pressure in passage (14) is equal to the pressure in passage (16). The oil in port (12) flows through passage (16) and the oil continues to the primary resolver in the priority flow control valve. If the oil pressure of the resolver is higher than the oil pressure of the steering resolver, this will cause the resolver to meter.
As the resolver valve is metering, oil from the decking blade flows to the pump compensator valve. The oil from the decking blade adjusts pump output according to the load.
When the operator releases the control lever, solenoid (19) deactivates. Springs (18) will respond to the solenoid and spool (3) will return the spool to the HOLD position. The decking blade will remain in this position until the operator moves the control lever again.
LOWER Position
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| Illustration 3 | g01222520 |
Decking Blade Valve (1) Proportional solenoid (2) Check valve (3) Control spool (4) Passage to tank (5) Signal passage (6) Chamber (7) Port to head end of cylinders (8) Spool (9) Pump passage (10) Passage (11) Passage (12) Port to rod end of cylinders (13) Spring cavity (14) Signal port from resolver (15) Spring (16) Signal passage (17) Passage to tank (18) Springs (19) Proportional solenoid | |
When the operator places the control lever in the LOWER position, pilot oil activates the solenoid (1). Spool (3) moves downward. Pump oil enters through passage (9). Oil flows into passage (10) through openings in spool (8). Then, the oil flows into chamber (6) .
Pressure in chamber (6) rises and the pressure acts against spool (8). The pressure overcomes the force of spring (15) and this causes spool (8) to move downward. As spool (8) moves downward, oil flows from passage (9) into passage (11) .
As spool (3) starts to move downward, oil flows past the spool into signal passage (5) and the oil flows back to the pump control. This causes the pump to upstroke.
When spool (3) moves down far enough, the oil flows from passage (11) past the spool into port (7). Most of this oil flows into the head ends of the cylinders and this causes the rods to extend. When the rods extend, the blade will lower.
Some of the oil in port (7) flows into signal passage (5). As the cylinders extend, this will force the oil from the rod ends of the cylinders. This oil flows into port (12), past spool (3), and into passages (16) and (17). Then, the oil flows from passage (17) back to the hydraulic tank.
In the LOWER position, pressure in passage (14) is equal to the pressure in passage (5). When the operator releases the control lever, springs (18) at either end of spool (3) will return the spool to the HOLD position.
The rest of the oil in port (7) flows through passage (5) to the secondary resolver in the steering control valve. If the oil pressure for the resolver of the decking blade is higher than the oil pressure of the steering resolver, then metering of the secondary resolver for the steering occurs.
Then, the oil flows to the primary resolver in the priority flow control valve. If the oil pressure for the resolver of the decking blade is higher than the oil pressure of the primary resolver, then metering of the primary resolver for the brake occurs.
As the resolver valve is metering, oil from the decking blade flows to the pump compensator valve. The oil from the decking blade adjusts pump output according to the load.
Check valve (2) is mounted in passage (7) to the head ends of the cylinders for the decking blade. A spring and oil pressure in the spring chamber hold the valve closed.
The pressure of the oil in passage (7) is low, if not enough oil flows to the head ends of the cylinders. The higher return oil pressure in passage (12) opens valve (2) and return oil flows from passage (4) to the head ends of the cylinders.
The valve opens, if not enough pump oil flows to the head ends of the cylinders for the decking blade. The valve will also open when the control valve spool is in the LOWER position.