RETURN TO NEUTRAL MECHANISM FOR HYDRAULIC PUMP

摘要

A hydraulic pump includes a housing (12), a cylinder block (14), a plurality of pistons (16), a swash plate (18), a trunnion arm (22), a first biasing assembly (54), and a second biasing assembly (56). The cylinder block includes a plurality of piston chambers. The swash plate is disposed for pivotal movement in the housing and cooperates with the pistons to vary the working volume of the piston chambers. The swash plate is pivotal about a pivot axis (80). The trunnion arm includes a cylindrical shaft portion (140) and a cam portion (142) connected with or integrally formed with the shaft portion. The trunnion arm is operatively connected with the swash plate for controlling pivotal movement of the swash plate. The cylindrical shaft portion defines a trunnion arm rotational axis (144) that is parallel to and offset from the pivot axis (80). The cam portion is disposed within the housing and includes a first lateral cam surface (154) and a second lateral cam surface (156) disposed on an opposite side of a cam portion axis (158) that extends through the cam portion, intersects the trunnion arm rotational axis and is perpendicular to the trunnion arm rotational axis. The first biasing assembly (54) is disposed in the housing and cooperates with the first lateral cam surface to urge the cam portion in a first direction toward a neutral position. The second biasing assembly (56) is disposed in the housing and cooperates with the second lateral cam surface to urge the cam portion in a second direction toward the neutral position. The second direction is opposite to the first direction.