Control device for hydrostatic pumps or motors

Claim 1

A CONTROL DEVICE FOR HYDROSTATIC PUMPS OR MOTORS COMPRISING A HOLLOW BODY DIVIDED BY A CENTRAL WALL INTO TWO MUTUALLY INTERCONNECTED PARTS, IN THE FIRST PART BEING SLIDABLY ACCOMMODATED A DISTRIBUTION VALVE CONTROLLING THE FLOW OF CONTROL LIQUID TO AN INTAKE BRANCH OF A SERVOACTUATED STROKING CYLINDER COUPLED TO A MEMBER VARYING THE DISPLACEMENT OF THE PUMP, SAID DISTRIBUTION VALVE BEING LOADED BY A SPRING AND HAVING TWO ANNULAR CIRCUMFERENTIAL SPACES ON AN AXIAL PART, THE FIRST ANNULAR SPACE COMMUNICATING VIA HOLES IN THE AXIAL PART WITH AN INTERNAL SPACE OF SAID DISTRIBUTION VALVE, THE OTHER ANNULAR SPACE COMMUNICATING VIA HOLES IN THE HOLLOW BODY WITH THE PRESSURE-LESS MEDIUM OF A CONTROL LIQUID TANK, A COLLAR SITUATED BETWEEN BOTH SAID ANNULAR SPACES MOVABLE TOGETHER WITH THE DISTRIBUTION VALVE AND OPENING AND CLOSING AN APERTURE IN THE HOLLOW BODY CONNECTED BY A TUBE TO THE AFOREMENTIONED SERVO-ACTUATED STROKING CYLINDER, THE OTHER PART OF THE HOLLOW BODY BEING CONNECTED TO THE PUMP OUTPUT BY AN INTAKE BRANCH, HAVING AN ORIFICE FORMED IN THE HOLLOW BODY, FROM WHICH THE PRESSURE CONTROL LIQUID THROUGH AN OUTLET BRANCH FLOWS TO DRIVEN HYDROSTATIC MOTORS, IN SAID OTHER PART OF THE HOLLOW BODY BEING SLIDABLY ACCOMMODATED A PRESSURE MEASURING MEMBER HAVING THE SHAPE OF A DIFFERENTIAL PISTON LOADED BY A SPRING AND VARYING BY ITS MOVEMENT THE ACTIVE CROSS SECTION OF SAID ORIFICE IN RELATION TO THE PRESSURE OF THE CONTROL LIQUID, THE INTAKE BRANCH BEFORE THE ORIFICE BEING CONNECTED TO A SPACE AT ONE SSIDE OF THE DISTRIBUTION VALVE, AN INNER SPACE OF THE PRESSURE MEASURING MEMBER BEING CONNECTED WITH A SPACE ON THE OTHER SIDE OF THE DISTRIBUTION VALVE.