| 摘要 |
Provided is a slewing-type working machine capable of reducing back pressure generated during slewing. The slewing-type working machine includes: a base carrier; an upper slewing body; a hydraulic motor 11 including first and second ports 11a and 11b and slewing the upper slewing body; a hydraulic pump 10, a slewing operation device 12 including an operating member 12a; a control valve 13 controlling the hydraulic motor 11 based on the operation signal of the slewing operation device 12; first and second pipe-lines 14, 15 connecting the first and second ports 11a and 11b of the hydraulic motor 11 to the control valve; a communication switching device 25 and 26 capable of switching communication and cutting of between both pipe-lines 14, 15 and the tank T; and a switching command section 27 operating the communication switching devices 25 and 26, when the upper slewing body is slewed, to bring only a pipe-line, which corresponds to a discharge-side pipe-line of the hydraulic motor 11, of the pipe-lines 14 and 15 into communication with the tank T, while bypassing the control valve 13. |
