ROTATION-TYPE WORKING MACHINE

摘要

Provided is a safe slewing-type working machine with high energy recovery efficiency, including a base carrier, an upper slewing body, a hydraulic motor 11 slewing the upper slewing body, a hydraulic pump 10, a slewing operation device 12, a control valve 13 controlling the hydraulic motor 11 based on an operation signal therefrom, pipe-lines 14 and 15 connecting the hydraulic motor 11 to the control valve 13, a hydraulic pressure source 28, communication valves 25 and 26 switching communication and cutoff between the pipe-lines 14 and 15 and a tank T by pilot pressure, an electric motor 29, an electric storage device 30, communication selector valves 32 and 33 provided on inlet sides of the communication valves 25 and 26, a switching control valve 41 provided on an inlet side of the communication selector valves 32 and 33, and a controller 27. During slewing deceleration, the controller 27 issues commands to switch the switching control valve 41 to the connecting position and switch the communication selector valves 32 and 33 to a pilot pressure supply position. In a slewing stopped state, the controller 27 issues commands to switch the communication selector valves 32 and 33 to the cutoff position and switch the communication valves 25 and 26 to the communication cutoff position.