Steering Hydraulic System
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| Illustration 1 | g00650169 |
(1) Hydraulic oil tank. (2) Gear pump. (3) Relief valve. (4) Fan Motor. (5) Metering pump. (6) Line to propel charge filter. (7) Steering cylinders. (8) Gerotor. (9) Rotary sleeve. (10) Priority valve. | |
Operation in a Right Turn
For a right turn, the motion of the steering wheel moves the rotary sleeve (9). This activates the bottom portion of the rotary sleeve. The pilot signal oil from the metering pump limits the steering system pressure to a maximum of 19000 kPa (2760 psi). The oil pressure and the spring force on the top of the priority valve (10) causes the valve to move down. This allows oil to flow from the gear pump to the metering pump (5). Priority flow goes through the rotary sleeve and the gerotor (8). Then, the flow goes to the head end of the left cylinder and the rod end of the right cylinder. The steering cylinders pivot the front end of the machine so that the compactor turns right.
If the load signal oil reaches 19000 kPa (2760 psi), the relief valve (3) will open and the excess pilot pressure will be dumped to the pump inlet. At this point, the force of the oil pressure that is on the bottom of priority valve (10) overcomes the force that is exerted on the top of the priority valve. This causes the priority valve to move up and this reduces the oil flow to the steering system.
Oil that is forced out of the opposite ends of the steering cylinders (7) flows back to the rotary sleeve (9). The oil continues to the charge filter in order to serve the charge circuit.
Operation in No Turn
The centering springs return the rotary sleeve (9) to the middle position when the compactor is not in a turn. The gear pump (2) delivers oil to the rotary sleeve and the oil is blocked from the steering cylinders (7). The pilot signal oil from the metering pump (5) is equal to charge pressure. The force of the oil pressure that is on the bottom of priority valve (10) overcomes the force that is exerted on the top of the priority valve. This causes the priority valve to move up and the majority of the oil to the rotary sleeve is blocked. At this point, the oil is ported to the charge circuit and the other implement circuits.
Leveling Blade Hydraulic System
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| Illustration 2 | g00650415 |
(1) Valve body. (2) Spool. (3) Passage to head end of cylinder. (4) Leveling blade cylinder. (5) Passage to rod end of cylinder. (6) Relief valve. (7) Passage to charge circuit. (8) Passage from gear pump. | |
HOLD Position
In the HOLD position, spool (2) stops the pressure oil to passages (3) and (5). The oil in passage (3) and oil in passage (5) is blocked. This holds the blade in position.
Pressure oil from inlet passage (8) flows across spool (2) to outlet passage (7) .
RAISE Position
When the spool is shifted from the HOLD to the RAISE position, the spool is moved downward. Pressure oil is sent from inlet passage (8) to the rod end of the cylinder through passage (5). This causes the blade to raise.
With spool (2) in the RAISE position, the passage from the head end of the cylinder (3) is open to outlet passage (7) .
LOWER Position
When spool (2) is shifted from the HOLD position to the LOWER position, the spool is moved upward. Pressure oil is allowed to flow from inlet passage (8) to the head end of the cylinder through passage (3). This causes the blade to lower.
With spool (2) in the LOWER position, the passage from the rod end of the cylinder (5) is open to outlet passage (7) .
FLOAT Position
When spool (2) is shifted from the HOLD position to the FLOAT position the spool is moved all the way upward. Spool (2) is held in the FLOAT position until the operator moves the blade control lever out of the FLOAT position.
With the control valve in the FLOAT position, spool (2) blocks pressure oil in inlet passage (8). The rod end of the cylinder (5) and the head end of the cylinder (3) are open to the charge circuit (7). This allows the blade to follow the shape of the ground.