Abstract: Control valve assemblies are taught which can be inserted into or associated with a basic primary unit for causing such basic primary unit to perform with optimum performance characteristics as a pump or motor, and a master or slave unit, etc. The function that the basic primary unit performs depends upon the control valve assembly selected. In the preferred embodiment of the control valve assembly, there is provided a central coaxial probe which passes through a bore in the spool valve body and is reponsive to a signal which is in addition to the other signals being sensed by the control valve assembly.

Abstract: The invention provides an axial piston pump/motor in which clearance at the port face between a stationary fluid distribution block and a rotating cylinder barrel is controlled in accordance with impedanced working fluid pressure applied to a hydrostatic bearing.

Abstract: The invention provides a capsule for damping pressure pulses in the working fluid of piston pumps and motors, the capsule being formed with co-axial inner and outer pervious walls which serve to limit the contraction and expansion of a flexible gas-filled bag enclosed between them.

Abstract: The application discloses a system which includes a prime mover driving a variable displacement type pump which in turn drives a variable displacement type motor all coordinated by a control system. Details of valves employed in the control system are disclosed as well as the overall interconnection of such valves with the engine, pump and motor. The control system controls the amount of fuel supplied to the engine, pump displacement, and motor displacement in such a manner as to achieve optimum performance.