TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
STEERING SYSTEM - CONTINUED
2.
Secondary Steering. Steering wheel is connected to metering pump by steering column. If piston pump fails, steering
oil pressure is lost and a switch in pressure line closes. When switch closes, a signal is sent to dash panel to illuminate
alert indicator for primary steering system. Light will notify operator of pump failure. When secondary steering pump is
energized, a signal will be sent to dash panel to illuminate indicator for secondary steering system. Light will notify
operator that secondary steering system is active. Secondary steering pump will provide oil to steer machine.
3.
Piston Pump (Steering and Pilot).
a.
Piston pump supplies oil to pilot system, steering system and work tools.
b.
Piston pump for work tools and piston pump for pilot system and steering system have: variable displacement, load
sensing, compensation for pressure, and compensation for flow. Piston type pumps have variable flow and pressure
dependent on system demands sensed by pressure and flow compensator valves. Pressure and flow compensator
valve for work tools piston pump is not shown.
c.
When engine is OFF, there is no load sensing signal to pressure and flow compensator valve. Margin spring pushes
flow compensator spool completely right. Any pressure behind actuator piston is vented to case drain across flow
compensator spool.
d.
When there is no pressure behind actuator piston, bias spring is able to hold swashplate at maximum angle.
e.
When engine is started, drive shaft starts to rotate. Oil flows into piston bore from pump inlet. Oil is forced out of
pump outlet and into system as cylinder barrel assembly rotates.
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