Abstract: A torque control for a hydrostatic piston pump that provides for a servo piston rod that is connected to the swashplate of the pump and connected to a servo piston within a first cavity that receives compensation pressure that urges the servo piston toward the swashplate. The servo piston has a stem that extends into a bore and is in contact with the stem of a maximum displacement piston that extends into a second cavity that is acted upon by system pressure to urge the maximum displacement piston toward the swashplate. Additionally, within the second cavity is a set of Bellville washers that surround the stem of the maximum displacement piston to limit the movement of the maximum displacement piston toward the swashplate.

Abstract: A hydraulic pump is disclosed having an adjusting member for varying yoke angle. The present adjusting member includes a control piston for displacing the yoke so as to define a desired yoke angle. A stop member is provided having threads and retained within the control piston. An adjusting screw for rotational motion is provided and includes an O-ring and a back up ring for sealing between the screw and the pump housing. The screw also includes a threaded portion for engaging the threads of the stop member. Rotation of the screw advances the threads while remaining stationary, displacing the control piston to limit the maximum inclination of the yoke.