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| Illustration 1 | g00425113 |
Steering System During a Right Turn (1) Hydraulic oil tank. (2) Gear pump. (3) Relief valve. (4) Fan Motor. (5) Metering pump. (6) Steering cylinders. (7) Gerotor. (8) Rotary sleeve. (9) Priority valve. | |
Operation in a Right Turn
For a right turn, the motion of the steering wheel moves the rotary sleeve (8). This activates the bottom portion of the rotary sleeve. The pilot signal oil from the metering pump increases the charge pressure to a maximum of 19000 kPa (2755 psi). The oil pressure and the spring force on the top of the priority valve causes the valve to move down. This allows oil to flow from the pump to the metering pump (5). Priority flow goes through the rotary sleeve and the gerotor (7). 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 pilot signal oil reaches 19000 kPa (2755 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 (9) overcomes the force that is exerted on the top of the priority valve. This causes the priority valve (9) to move up and this reduces the oil flow to the steer system.
Oil that is forced out of the opposite ends of the steering cylinders (6) flows back to the rotary sleeve (8). 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 (8) 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 (6). The pilot signal oil from the metering pump (5) is basically charge pressure. The force of the oil pressure that is on the bottom of priority valve (9) 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.