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A control system for a variable displacement pump which powers a load actuator via a selector valve and which has its displacement varied by a pump actuator of the single-acting type. The system includes a load-sensing control valve for selectively communicating the pump actuator with a pressurized

A control system for a variable displacement pump which powers a load actuator via a selector valve and which has its displacement varied by a pump actuator of the single-acting type. The system includes a load-sensing control valve for selectively communicating the pump actuator with a pressurized fluid source or with a fluid drain in accordance with a differential between the sum of the pump output pressure and the pump actuator pressure and the sum of the load actuator pressure and the force of a spring. Also included is a normally open, cutoff control valve, connected serially with the load-sensing control valve, for placing the pump actuator in communication with a fluid drain in response to the sum of the pump output pressure and pump actuator pressure acting against the force of a spring.

대표청구항 ▼

A hydraulic control system for a variable displacement hydraulic pump powering a load actuator, comprising in combination: a pump actuator for adjusting the displacement of the pump; a source of hydraulic fluid under pressure for powering the pump actuator; a load-sensing control valve including fir

A hydraulic control system for a variable displacement hydraulic pump powering a load actuator, comprising in combination: a pump actuator for adjusting the displacement of the pump; a source of hydraulic fluid under pressure for powering the pump actuator; a load-sensing control valve including first resilient means and adapted to control communication between the pump actuator and the source in accordance with a differential between the sum of the output pressure of the pump and the pressure of the pump actuator and the sum of the pressure of the load actuator and the force of the first resilient means; and a cutoff control valve connected serially with the load-sensing control valve and including second resilient means, the cutoff control valve being adapted to control communication between the pump actuator and the source in accordance with a differential between the force of the second resilient means and the sum of the output pressure of the pump and the pressure of the pump actuator.