CONTROL GP 1601756 - Caterpillar

Illustration 1 g01799493
(1) Signal oil (2) Adjustment screws (3) Pump control valve (4) Pressure compensator spring (pressure cutoff) (5) Oil flow to the pump case (6) Oil flow to the control piston (7) Oil flow from the output port of the pump (8) Pressure compensator spool (pressure cutoff) (9) Flow compensator spool (margin pressure) (10) Flow compensator spring (margin pressure) (AA) Pump output oil (BB) Low control oil pressure (EE) Signal pressure (LL) Hydraulic tank or case drain oilPump control valve (3) automatically keeps pump pressure and pump flow at a level that is needed to fulfill the system load and the system flow needs. When none of the hydraulic implements and steering circuits are being used, the pump is at low pressure standby. However, if one or more of the circuits are being used, a signal resolver valve compares the signal pressure of the implement control valve and the steering signal pressure. The highest resolved signal pressure is then routed to the pump control valve. Pump control valve (3) will then signal the pump to maintain flow and pressure requirements. The margin pressure is approximately 2100 kPa (305 psi) higher than the signal pressure. The difference between the pump signal and the pump output is called the margin pressure.If low pressure standby is below 2660 kPa (380 psi) or above 4000 kPa (580 psi), the margin pressure should be checked. If the margin pressure is out of the specification, adjust the margin pressure.ReferenceRefer to the Testing and Adjusting, "Pump Control Valve (Implement, Steering) - Test and Adjust" section.The pump control valve also has the ability to limit system pressure in order to prevent hydraulic overloads. If the system pressure raises quickly, the pressure compensator will override the flow compensator. This will lower the output flow of the pump. This action starts below the setting of the implement relief valve. This protects the hydraulic system from damaging high pressures.