Patent ID: 7506505

Claim:
A hydraulic driving device for an operating machine, comprising: an actuator ( 2 ); a pump ( 3 ) to discharge a hydraulic fluid by driving a motor therein; an oil passage ( 4 a ) to introduce the hydraulic fluid discharged from the pump to the actuator; a hydraulic control valve ( 6 ) provided in the oil passage to control an oil pressure of the hydraulic fluid that is introduced to the actuator; an open and closed valve ( 5 ) to control opening and closing of the oil passage between the pump and the hydraulic control valve; an operating device ( 7 ) with which a driver operates the actuator; and a controller ( 8 ) adapted to control an opening of the hydraulic control valve and the open and closed valve in accordance with an output value of the operating device, wherein: the controller is adapted to: stop the pump, and close the open and closed valve and the hydraulic control valve respectively when the output value of the operating device is in a first predetermined range (E 1 ,E 2 ); start the pump and open the open and closed valve when the output value goes beyond the first predetermined range; and open the hydraulic control valve to supply the hydraulic fluid to the actuator when the output value goes beyond a second range (E 3 ,E 4 ); greater than the first predetermined range.