CIRCUIT CAPABLE OF VARYING PUMP DISCHARGE VOLUME IN CLOSED CENTER-LOAD SENSING SYSTEM.

摘要

The load sensing system comprises a power source (1) having a rotary speed indicator. A variable volume hydraulic pump (2) is driven by the power source. Actuators (3,4) are driven by pressure oil discharged from the variable volume hyudraulic pump. Change-over valves (7,8) control the flow of this pressure oil. An indicator (31) sets a rotary speed of the power source in the load sensing system in which the difference between the pump pressure and the load pressure of the actuators is held at a predetermined level, and, when this difference is changed. A flow rate of the oil is discharged from the variable volume hydraulic pump is changed. A controller (33) calculates and outputs the rotary speed of the power source in response to a command signal from the indicator. An electronic proportional control governor (32) controls the rotary speed of the power source in response to a command signal from the controller.