TM 5-3895-383-24
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 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.
12-18
