Hydraulic mechanism, such as a motor or a pump, having radial pistons adapted to perform a plurality of strokes per revolution

A hydraulic mechanism, such as a motor or pump, having radial pistons adapted to perform a plurality of strokes per revolution, comprising:

• an enclosed housing;
• a stator mounted in said housing;
• a rotor rotatably mounted in said housing for rotary movement with respect to said stator;
• said rotor having a plane face thereon through which fluid is supplied and exhausted to reciprocate said pistons;
• a stationary fluid-distributor slide valve on said stator having a plane face opposite the plane face on said rotor, and defining an interface therebetween said stator and said rotor defining therebetween an enclosed balancing chamber in communication with the periphery of said interface between the rotor and slide valve;
• said housing defining a substantially pressure-free enclosure surrounding said rotor, said distributor slide valve being located within said balancing chamber;
• and
• means for providing communication between said balancing chamber and said pressure-free enclosure and for maintaining pressure in said enclosure;
• whereby the effect of pressure of fluid in said balancing chamber on said distributor slide valve will oppose the effect of pressure of fluid acting on said slide valve in the regon of said interface to substantially balance this effect.