THEORY OF OPERATION - CONTINUED
STEERING SYSTEM - CONTINUED
Actual system pressure will be greater than highest work port pressure requirements unless pump is at full stroke.
Difference between work port requirement and higher main system pressure is called margin pressure.
Pressure compensator valve also limits maximum system pressure to prevent damage to steering system compo-
nents caused by excessive pressure.
Pump is controlled by bias piston and actuator piston. Bias spring causes swashplate to move, which causes pump
Actuator piston has a larger area than bias piston. Actuator piston causes swashplate to destroke pump. Flow com-
pensator spool and/or pressure compensator spool changes pump output by regulating pump discharge pressure
acting on actuator piston.
Pressure and flow compensator valve routes pump discharge pressure to actuator piston. Because actuator piston is
larger than bias piston, oil pressure acting against piston overcomes force of bias spring, causing pump to destroke.
Flow compensator spool maintains pump outlet pressure at 350 ± 15 psi (2,400 ± 100 kPa) above work port pres-
Pressure and flow compensator valve also controls maximum output pump pressure. When work port pressure
rises above 3,046 ± 51 psi (21,000 ± 350 kPa), pressure compensator spool overrides flow compensator spool,
causing pump to destroke. This occurs at approximately 100 psi (700 kPa) below maximum pressure setting.