Hydraulic positioning servo system

Claim 1

A HYDRAULICALLY POSITIONED SERVO SYSTEM WHICH INCLUDES A POWER CYLINDER AND A HYDRISTOR AS A POSITION FEED BACK ELEMENT AND INPUT VALVE, SAID POWER CYLINDER PROVIDED WITH A PISTON, SAID HYDRISTOR COMPRISING A VALVE THAT IS PROVIDED WITH A METERING ELEMENT MOUNTED THEREIN, SAID METERING ELEMENT PROVIDED WITH TWO OPPOSED SURFACES TO DIVIDE SAID VALVE INTO TWO MOVABLE OPPOSITELY SLANTED SURFACES, SAID METERING ELEMENT MOVABLE IN EITHER DIRECTION TO CHANGE THE RATIO PRODUCED BY SAID OPPOSITELY SLANTED SURFACES IN RELATION TO ITS POSITION, SAID VALVE PROVIDED WITH TWO INLET PORTS, SAID INLET PORTS CONNECTED TO ORIFICES THAT ARE DIRECTED TOWARD SAID OPPOSED SLANTED SURFACES OF SAID VALVE, AN OUTLET PORT OPEN TO BOTH ORIFICES, SAID OPPOSED SLANTED SURFACES MOVABLE TOWARD OR AWAY FROM SAID ORIFICES TO PRODUCE TWO COMPLEMENTARY FLUID FLOWS, SAID HYDRISTOR PROVIDED WITH A METERING CAM FITTED TO SAID PISTON OF SAID POWER CYLINDER AND PARALLEL THERETO, SAID METERING CAM PROVIDED WITH A SLANTED SURFACE TO BEAR AGAINST THE END OF SAID METERING ELEMENT OF SAID HYDRISTOR, SAID METERING ELEMENT RESILIENTLY RETAINED IN CONTACT WITH SAID METERING CAM, SAID SERVO SYSTEM DIVIDED INTO A POWER STAGE AND FEED BACK CONTROL STAGE, SAID POWER STAGE COMPRISING SAID POWER CYLINDER AND PISTON, A MAIN PRESSURE SOURCE AND A FOUR WAY VALVE, SAID FOUR WAY VALVE CONNECTED BY FLUID LINES TO SAID POWER CYLINDER, SAID FEED BACK CONTROL STAGE COMPRISING SAID HYDRISTORAN AUXILIARY PRESSURE SOURCE, A RATIO FLOW DIVIDER SERVING AS A SIGNAL INPUT VALVE TO PROVIDE TWO COMPLEMENTARY FLUID FLOWS AND TWO COMPLEMENTARY RESISTANCES, A DIFFERENTIAL PRESSURE SENSING DEVICE WHICH IS MECHANICALLY CONNECTED TO SAID FOUR WAY VALVE AND CONNECTED BY FLUID LINES TO SAID RATIO FLOW DIVIDER AND TO SAID HYDRISTOR, SAID FOUR WAY VALVE CONNECTED TO SAID MAIN PRESSURE SOURCE COMPRISING A VALVE BODY WITH A CENTRAL AXIALLY MOVABLE PISTON HAVING FLUID FLOW CONTROLLING LANDS THEREON TO SEPARATE AND GUIDE SAID FLUID FLOW TO EITHER SIDE OF SAID POWER CYLINDER, SAID HYDRISTOR HAVING ITS METERING ELEMENT MECHANICALLY CONNECTED TO THE MOVING PISTON OF SAID POWER CYLINDER AS A FEEDBACK ELEMENT, SAID RATIO FLOW DIVIDER COMPRISING A CLOSED CASING