A Power Summation Control System for Fixed Displacement Pumps

A new fluid power pump control system has been developed. This dual-sensing control system monitors the power demands of two separate hydraulic circuits and limits these demands over a wide range of combinations of pressures in each circuit. The technique provides a stepwise approximation to the familiar horsepower curve and results in a high degree of engine power utilization when applied to circuits such as the implement circuits of an excavator.

The two-speed nature of the control system of each tandem pump extends beyond the implement circuit and allows manual or automatic two-speed track drive. It also provides reduced flow to the implement circuit for precise tool control even at maximum engine speed.