L4-4 Steering Circuit L04037
No Steer
(Refer to Figure 4-3):
High pressure oil from the steering pump and steer-
ing accumulators is available through the steering
bleeddown manifold to the HP port on the flow ampli-
fier assembly.
Upon Entering the priority valve, it goes past the
spool to the closed amplifier valve and also out port P
through a hose to port P on the steering control unit.
In the control unit, it goes to a closed area in the con-
trol valve.
As pressure builds up in these two areas, oil passes
through orifices in the end of the priority valve and
builds pressure on the end of the valve and port PP.
When pressure reaches approximately 500 psi (3
447 kPa), the spool moves compressing its spring
and closes off oil supply through area “A” resulting in
only 500 psi (3 447 kPa) at the amplifier spool, steer-
ing control unit, and PP port.
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