Patent ID: 7469535

Claim:
A hydraulic operation controlling unit, comprising: an engine; a hydraulic pump that is operated by the engine; a hydraulic actuator that is operated by pressurized oil that is discharged from the hydraulic pump; an engine controlling means for controlling an output of said engine; and a hydraulic pump absorbing torque controlling means for controlling an absorbing torque of said hydraulic pump, wherein: a matching point where an output torque of said engine and the absorbing torque of said hydraulic pump coincide with each other is predetermined in accordance with work requirements, said engine controlling means controls the output of said engine such that a power output of said engine is constant or approximately constant in a predetermined engine speed range which includes an engine speed that corresponds to said matching point, and said hydraulic pump absorbing torque controlling means controls the absorbing torque of said hydraulic pump such that the output torque of said engine that corresponds to said matching point and the absorbing torque of said hydraulic pump are made to coincide with each other by increasing or reducing the absorbing torque of said hydraulic pump in accordance with an increase and a decrease in the engine speed.