Rotary Hydraulic Machine and Controls

A rotary hydraulic machine having a rotating group including a plurality of variable capacity chambers defined by pistons sliding within respective cylinders, said pistons being displaceable relative to said cylinders upon rotation of said group to vary the volume of said chambers and thereby induce a flow of fluid through said chambers from an inlet port to an outlet port, an adjustment assembly including an actuator operable upon said rotating group to adjust the stroke of said pistons and thereby vary the capacity of said machine, a fluid supply for said actuator and a control valve to control flow to said actuator, said valve having a first position in which flow through said valve is inhibited and being movable from said first position to vary the capacity of said machine, said valve being controlled by a controller having an output to adjust said valve and receiving input signals from at least one transducer, said one transducer sending a signal representative of pressure delivered at said outlet port and said controller operating upon said actuator to maintain pressure at said outlet at a predetermined value.