Abstract: The invention provides a hydraulic drive apparatus which obtain a desired speed reduction ratio and a reduced shock during clutch engagement. Accordingly, the hydraulic drive apparatus for a working machine has a variable capacity type first (8) and second hydraulic motor (11), a first input shaft (5) and a second input shaft connected respectively (7). The hydraulic drive apparatus transmits a torque from the first and the second hydraulic motor to an output shaft (2). A planetary gear (21) is interposed between the second hydraulic motor and the second input shaft, and a clutch (10) freely engaging the second hydraulic motor with the second input shaft is provided between a ring gear (29) of the planetary gear and a housing (24). A modulation damper (22) for reducing a clutch pressure (P3) before the engagement and reducing at a time of engagement is provided.

Abstract: A hydraulic control system for a spooling drum of a reversible hoisting winch of the type having a bidirectional hydraulic motor for driving the drum via two planetary drives in series, with the final planetary drive having a spring-loaded brake which, when actuated hydraulically, allows the drum to freewheel. The control system comprises a shuttle valve connected between a pair of conduits through which the bidirectional drive motor is placed in selective communication with a first pump and a fluid drain by a motor control valve. Pilot-operated from the shuttle valve is a selector valve which, in response to the pilot signal supplied when the motor is in rotation in either direction, delivers pressurized hydraulic fluid from a second pump to a lubricating circuit of the planetary drives. When the motor control valve is neutralized, setting the drive motor out of rotation, the selector valve delivers the output of the second pump to the brake for freewheeling the winch drum.