Abstract: An integrated valve system (51) for use with a variable displacement hydrostatic pump (11), including a relief and check valve assembly (75) and a pressure override (POR) section, operable to communicate pressure above a predetermined POR setting from the high pressure side (15) of the HST closed loop to a stroking cylinder (29) to destroke the pump (11). A high pressure relief spring (83) determines the relief setting, and a POR compression spring (109) determines the POR setting, the relief spring and the POR spring being seated independently of each other, such that the POR setting may be adjusted without effecting the operation of the relief and check valve assembly (75).

Abstract: An integrated valve system (51) for use with a variable displacement hydrostatic pump (11), including a relief and check valve assembly (75) and a pressure override (POR) section, operable to communicate pressure above a predetermined POR setting from the high pressure side (15) of the HST closed loop to a stroking cylinder (29) to destroke the pump (11). A high pressure relief spring (83) determines the relief setting, and a POR compression spring (109) determines the POR setting, the relief spring and the POR spring being seated independently of each other, such that the POR setting may be adjusted without effecting the operation of the relief and check valve assembly (75).

Abstract: A swashplate centering and holddown mechanism (55) for an axial piston unit (11) comprising a cylinder barrel (29) disposed for rotation about an axis of rotation (A). A cam member (39) is tiltable about a transverse axis and has a swashplate (37). The swashplate (37) is perpendicular to the axis of rotation (A), in a neutral position, and has a displaced position (FIG. 4). The swashplate centering and holddown mechanism biases the cam member (39) axially toward a cradle surface (41) and pivotably toward the neutral position (FIG. 3). The mechanism (55) comprises a pair of arms (67,69), each of which defines a pivot location (71,73), at one axial end thereof, fixed relative to a pump housing (19) on one side of the axis of rotation (A), and a swashplate-engaging portion (95,97), at the opposite axial end thereof, engaging the swashplate, on the other side of said axis of rotation (A), when said swashplate is in neutral.