Axial piston hydraulic units

Claim 1

IN AN HYDRAULIC UNIT OF THE TYPE INCLUDING A CASING, A CYLINDER BLOCK MOUNTED FOR ROTATION WITHIN THE CASING, SAID CYLINDER BLOCK HAVING A PLURALITY OF AXIALLY EXTENDING BORES THEREIN EACH DEFINING A WORKING CYLINDER, A WORKING PISTON WITHIN EACH BORE, A DRIVING FLANGE MOUNTED FOR ROTATION ABOUT AN AXIS DISPOSED AT AN ANGLE TO THE AXIS OF THE CYLINDER BLOCK, A PISTON ROD FOR EACH PISTON, MEANS CONNECTING THE PISTON RODS TO THE DRIVING FLANGE WHEREBY ROTATION OF THE FLANGE RECIPROCATES THE PISTONS IN THE CYLINDERS AND ROTATES SAID CYLINDER BLOCK WITHIN THE CASING, SAID CYLINDER BLOCK INCLUDING A BASE HAVING PORTS THEREIN IN COMMUNICATION WITH THE RESPECTIVE CYLINDERS, A VALVE PLATE FIXEDLY SUPPORTED WITHIN THE CASING AND HAVING A SURFACE IN FACING ENGAGEMENT WITH THE BASE OF SAID CYLINDER BLOCK, SAID VALVE PLATE HAVING INLET PASSAGES THERETHROUGH INCLUDING SEGMENTALLY SHAPED ADMISSION AND DELIVERY PORTS IN SAID SURFACE ADAPTED TO REGISTER WITH THE PORTS IN THE BASE OF THE CYLINDER BLOCK UPON RELATIVE ROTATION BETWEEN SAID CYLINDER BLOCK AND SAID VALVE PLATE, THE IMPROVEMENT COMPRISING SAID CYLINDER BLOCK AND VALVE PLATE, EACH HAVING AN AXIAL BORE THERETHROUGH HAVING THEIR AXES COINCIDENT WITH THE AXIS OF SAID CYLINDER BLOCK, A PORTION OF THE BORE THROUGH THE CYLINDER BLOCK ADJACENT SAID DRIVING FLANGE BEING SPHERICALLY SHAPED TO DEFINE A FIRST SEAT CONSTITUTING A SEGMENT OF A SPHERE, A PORTION OF THE BORE THROUGH THE VALVE PLATE REMOTE FROM SAID CYLINDER BLOCK BEING ENLARGED AND SPHERICALLY SHAPED TO DEFINE A SECOND SEAT CONSTITUTING A SEGMENT OF A SPHERE, A PIN MEANS EXTENDING THROUGH THE BORES IN THE VALVE PLATE AND CYLINDER BLOCK AND HAVING LESS DIAMETER THAN THE DIAMETER OF SAID BORES, A BALL-JOINT CONNECTION BETWEEN THE END OF THE PIN MEANS REMOTE FROM THE VALVE PLATE AND THE DRIVING FLANGE, A CUP-SHAPED BALANCING CYLINDER POSITIONED BETWEEN THE PIN MEANS AND THE CYLINDER BLOCK AND INCLUDING A WALL PORTION IN CO-OPERATIVE SLIDING ENGAGEMENT WITH A PORTION OF THE PIN MEANS AND A BASE HAVING AN EXTERNAL SURFACE DEFINED BY A SEGMENT OF A SPHERE CORRESPONDING TO AND ENGAGING WITH SAID FIRST SEAT ON THE CYLINDER BLOCK, A BUSHING SURROUNDING SAID PIN AND HAVING A SPHERICAL PORTION ENGAGING SAID SECOND SEAT ON THE VALVE PLATE, A THRUST WASHER CARRIED BY THE PIN AND HAVING A BEARING SURFACE IN ENGAGEMENT WITH SAID BUSHING, SAID PIN HAVING A LONGITUDINAL OIL-ACCOMMODATING BORE THERETHROUGH, AT LEAST A PART OF SAID WALL PORTION OF SAID BALANCING CYLINDER BEING SPACED FROM A PORTION OF THE PIN MEANS, SAID PIN MEANS HAVING RADIAL PORTS PROVIDING COMMUNICATION BETWEEN SAID LONGITUDINAL BORE AND THE SPACE BETWEEN THE PIN MEANS AND SAID PART OF THE WALL PORTION OF SAID BALANCING CYLINDER, SAID VALVE PLATE, BUSHING AND PIN MEANS HAVING BORES THERETHROUGH PROVIDING COMMUNICATION BETWEEN AT LEAST ONE OF SAID PORTS IN THE VALVE PLATE AND THE LONGITUDINAL OIL-ACCOMMODATING BORE IN THE PIN WHEREBY OIL UNDER PRESSURE CAN FLOW FROM SAID AT LEAST ONE PORT IN THE VALVE PLATE TO AND THROUGH THE LONGITUDINAL BORE IN THE PIN MEANS AND THENCE THROUGH SAID RADIAL PORTS THEREIN TO THE INTERIOR OF THE BALANCING CYLINDER TO APPLY AXIAL THRUST AGAINST SAID CYLINDER BLOCK IN A DIRECTION TOWARD SAID VALVE PLATE, AND THE REACTION OF SAID THRUST BEING ABSORBED BY SAID THRUST WASHER WHEREBY MINUTE ANGULAR DEVIATIONS BETWEEN SAID CYLINDER BLOCK AND SAID PIN MEANS AND BETWEEN SAID PIN MEANS AND SAID VALVE PLATE RESPECTIVELY CAN BE ACCOMMODATED WITHOUT DISTURBING THE CONTACT BETWEEN THE BASE OF THE CYLINDER BLOCK AND THE FACING SURFACE OF THE VALVE PLATE.