Hydraulic apparatus

Claim 1

IN A ROTARY PUMP OR THE LIKE, IN COMBINATION, A VALVE PLATE AND A CYLINDER BLOCK ROTATABLE RELATIVE TO THE VALVE PLATE AND HAVING CYLINDERS DISPOSED ABOUT ITS AXIS, THE COMPLEMENTAL SURFACES OF THE CYLINDER BLOCK AND VALVE PLATE BEING ARRANGED TO TRANSMIT THRUST BUT TO AFFORD BUT SLIGHT CLEARANCE BETWEEN THEM, SUCH SURFACE OF THE VALVE PLATE HAVING A HYDROSTATIC BALANCING RECESS OPENING INTO IT, AND WITH A SOLE RESTRICTING CONNECTION LEADING TO THE RECESS, A SEPARATE FEED PORT ALSO OPENING INTO SUCH SURFACE ADJACENT THE RESTRICTING CONNECTION, TWO KIDNEY-SHAPED PORTS IN SUCH SURFACE ARRANGED TO REGISTER DURING A ROTATIVE CYCLE WITH THE CYLINDERS OF THE CYLINDER BLOCK FOR INTAKE AND DISCHARGE, RESPECTIVELY, OF FLUID BETWEEN THE VALVE PLATE AND CYLINDER BLOCK, SAID RESTRICTING CONNECTION BEING LOCATED CONCENTRICALLY OF BUT RADIALLY OUTWARDLY OF SAID KIDNEY-SHAPED PORTS, AN ANNULAR RECESS IN THE VALVES''S SURFACE CONCENTRIC WITH AND LOCATED INTERMEDIATE SAID PORTS AND THE RESTRICTING CONNECTION, A CENTRAL CIRCULAR RECESS IN THE VALVE''S SURFACE LOCATED RADIALLY INWARDLY OF THE PORTS, THE ANNULAR RECESS AND THE CIRCULAR RECESS BOTH BEING IN COMMUNICATION WITH A LOW PRESSURE REGION, THE ROTATIVE CYLINDER BLOCK BEING FORMED IN ITS SURFACE THAT IS COMPLEMENTAL TO THE VALVE PLATE''S SURFACE SO AS TO CLOSE THE BALANCING RECESS AND THE RESTRICTING CONNECTION DURING THE GREATER PART OF ITS ROTATIVE CYCLE, APART FROM A LEAKAGE GAP RESULTING FROM THE SLIGHT CLEARANCE, AND THE CYLINDER BLOCK''S SURFACE ALSO HAVING A BRIDGING RECESS LOCATED TO AFFORD COMMUNICATION WITH BOTH SAID FEED PORT AND SAID RESTRICTING CONNECTION MOMENTARILY DURING EACH ROTATIVE CYCLE, FOR ACCESS OF PRESSURE LIQUID INTERMITTENTLY FROM THE FEED PORT TO THE RESTRICTING CONNECTION, AND THENCE TO THE BALANCING RECESS.