Drive assembly with pressure force aggregating piston arrangement for hydraulic motor speed/torque selector

摘要

A drive assembly includes a drive motor at least in part contained in a housing and having a rotor rotating an output shaft. A selector mechanism, at least in part contained in the housing, is movable into one of a plurality of orientations corresponding to one of a plurality of drive motor settings. An actuator, at least in part contained in the housing, is arranged to move the selector mechanism into one of the plurality of orientations. The actuator has first and second pistons each disposed in a piston chamber of the housing for movement by hydraulic pressure. The second piston is arranged in contact with the first piston and configured to aggregate and transfer forces from hydraulic movement of the first piston and the second piston to move the selector mechanism.