THEORY OF OPERATION - CONTINUED
STEERING SYSTEM - CONTINUED
When hydraulic system stalls under load or when cylinders reach end of stroke, main system pressure
increases. Signal pressure in metering pump signal line and pressure compensator cavity becomes equal to
pump output pressure. Flow compensator spring keeps flow compensator spool shifted downward.
When main system pressure reaches 3,046 ± 51 psi (21,000 ± 350 kPa) in passage, pressure acts upon pres-
sure compensator spool to overcome force of pressure compensator spring. Pressure then causes spool to
move upward. Supply oil now flows past flow compensator spool and through passage to pressure com-
pensator spool. Oil flows past pressure compensator spool and into passage, then flows to actuator piston.
Pressure sensed on actuator piston causes pump to destroke. If operator does not turn steering wheel, pump
will return to low-pressure standby.
Steering Metering Pump.