Spring return mechanism for axial piston machines

A variable delivery axial piston machine having a housing, a part angularly adjustable about an axis to vary the delivery of the machine and having a zero stroke position, mechanism for restoring said part to said zero stroke position, stops arranged on opposite sides of said axis and cooperating with said mechanism to define said zero stroke position, said mechanism comprising a movable yoke lever in contact with and movable relative to said angularly adjustable part, said yoke lever contacting said angularly adjustable part on opposite sides of said axis when said angularly adjustable part is in said zero stroke position and engaging said stops in said zero stroke position and being movable relative to said stops and said movable part and lifted off one of said stops on movement on said angularly adjustable part from said zero stroke position, a spring acting on said yoke lever to bias said yoke lever against said angularly adjustable part and said stops, said spring being a compression spring which lies along a line intersecting said axis, and a pivot connection between said spring and said yoke lever and located in the vicinity of said axis.

A variable delivery axial piston machine having a housing, a part angularly adjustable to vary the delivery of the machine and having a zero stroke position, mechanism for restoring the part to its zero stroke position, stationary stops which cooperate with said mechanism to define the zero stroke position, said mechanism comprising a movable yoke lever in contact with said adjustable part and engaging said stops in zero stroke position and moved relative to said stops on movement from a zero stroke position, a spring acting on said lever to bias said lever against said part and said stops, said angularly adjustable part being angularly adjustable about an axis, said spring being a compression spring which lies along a line intersecting said axis, said stops being fixed to the housing and adjustable, said yoke lever being swingable about one or the other of said stops on movement of said part from its zero stroke position, a pivot connection between said spring and said yoke lever and located in the vicinity of said axis, said yoke lever being provided with two circular-arc slots, and said stops are eccentric pins acting as stops and disposed at corresponding one ends of the respective slots when the angularly adjustable part is in the zero stroke position thereof, the center of curvature of each slot being situated in said one end of the other slot.