Patent ID: 8327638

Claim:
A hydraulic drive apparatus including a variable displacement hydraulic pump that is driven by an engine and a hydraulic motor of a variable capacity type that is driven by pressure oil discharged from the hydraulic pump, and outputting drive force of the hydraulic motor, the hydraulic drive apparatus comprising a pump control unit that includes: a pump reference command value setting unit that sets a pump reference command value for the hydraulic pump in accordance with an engine speed of the engine; a pump correction command value calculating unit that sets a pump command value by determining an inching rate in accordance with an amount of operation when an inching operation is performed, and correcting the pump reference command value in accordance with the inching rate; and a pump control command value setting unit that sets a pump control command value for controlling capacity of the hydraulic pump, based on the pump command value set by the pump correction command value calculating unit, wherein the pump control command value setting unit sets a pump control command upper limit in accordance with pressure of the pressure oil flowing between the hydraulic pump and the hydraulic motor, sets the pump command value to the pump control command value when the pump command value is equal to or smaller than the pump control command upper limit, and sets the pump control command upper limit to the pump control command value when the pump command value is larger than the pump control command upper limit.