DRAIN CIRCUIT OF HYDRAULIC MOTOR

PURPOSE:To reduce a manufacturing cost and prevent oil leakage by communi cating branch drain circuits branched from a drain circuit of a hydraulic motor with the respective main circuits between a counter balance valve and a rotary joint through check valves which check the flow in the direction of the hydraulic motor. CONSTITUTION:A drain circuit 31 of a hydraulic motor 21 is branched at a branch point 33. Branch drain circuits 24, 25 are respectively communicated with main circuits 9, 10 between a counter balance valve 32 and a rotary joint 8 through check valves 20, 21 which check flow in the direction of the hydraulic motor 32. In respect to the drain circuit 31 of the hydraulic motor 32, lining is prepared only by considering the branch drain circuits 24, 25, the check valves 20, 21, pipe passages 15, 16 and the main circuit 10. Remarkable manufacturing cost to be required to provide an exclusive communication passage for the drain circuit on the rotary joint or the like is dispensed.