To provide a hydraulic machine for slewing drive excellent in low speed sluing performance and precise in starting and stopping control.
The hydraulic machine wherein a hydraulic motor 4 is connected to a delivery circuit 3 of a variable displacement hydraulic pump 1 driven by a prime mover 2 through an open circuit 6 and a slewing body is connected to the hydraulic motor 4, is provided with a delivery rate controller 12 attached to the hydraulic pump 1 to vary the delivery rate in response to the manipulated variable of a slewing controller 14, and a pressure controller 10 attached to the hydraulic motor 4 to control the pressure at the outlet side of the motor in response to said manipulated variable. The machine as arranged in such a way, enables the operation of the delivery rate controller to increase the delivery rate while effecting the pressure controller to decrease the pressure at the outlet side of the motor, with the increase in the manipulate variable of the slewing controller.