US Patent 7124677 Swashplate assembly

A rotary hydraulic machine has a swashplate adjustable by an actuator. The swashplate has a part cylindrical bearing surface supported by a complimentary bearing surface in the housing and a fluid bearing acts between the surfaces. The fluid is supplied to the fluid bearing by pressure compensated flow control valves to maintain a predetermined flow of fluid. The actuator includes a pair of single acting hydraulic motors secured in the housing and acting on the swashplate at spaced locations. The pistons of the hydraulic motors engage cylindrical pins located on the swashplate to permit a rolling motion between the swashplate and motors as the swashplate is adjusted.