Axial piston hydraulic unit

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 SAID PISTONS IN THE WORKING CYLINDERS AND ROTATES SAID CYLINDER BLOCK WITHIN THE CASING, SAID CYLINDER BLOCK INCLUDING A BASE HAVING PORTS THEREIN IN COMMUNICATION WITH THE RESPECTIVE WORKING CYLINDERS, AND BASE HAVING A PLANAR OUTER SURFACE, A VALVE PLATE FIXEDLY MOUNTED WITHIN THE CASING AND HAVING A PLANAR SURFACE FACING AND ENGAGING THE PLANAR SURFACE OF THE BASE OF THE CYLINDER BLOCK, AND SAID VALVE PLATE HAVING INLET PASSAGEWAYS THERETHROUGH INCLUDING SEGMENTALLY SHAPED ADMISSION AND DELIVERY PORTS IN THE PLANAR SURFACE OF THE VALVE PLATE ADAPTED TO REGISTER WITH THE PORTS IN THE BASE OF THE CYLINDER BLOCK UPON RELATIVE ROTATION BETWEEN THE CYLINDER BLOCK AND VALVE PLATE, THE IMPROVEMENT COMPRISING SAID CYLINDER BLOCK AND VALVE PLATE EACH HAVING AN AXIAL BORE THERETHROUGH HAVING THEIR RESPECTIVE AXES COINCIDENT WITH THE AXIS OF SAID CYLINDER BLOCK, THE BORE THROUGH THE CYLINDER BLOCK HAVING AN ENLARGED PORTION DISPOSED INWARDLY FROM THE FACE THEREOF REMOTE FROM THE VALVE PLATE AND DEFINED BY A PORTION OF THE CYLINDER BLOCK SHAPED AS A SEGMENT OF A SPHERE AND CONSTITUTING A FIRST SEAT, THE BORE THROUGH THE VALVE PLATE INCLUDING AN ENLARGED PORTION REMOTE FROM SAID CYLINDER BLOCK AND DEFINED BY A PORTION OF THE VALVE PLATE SHAPED AS A SEGMENT OF A SPHERE AND CONSTITUTING A SECOND SEAT, A PIN INCLUDING A PORTION EXTENDING THROUGH THE BORES IN THE CYLINDER BLOCK AND VALVE PLATE, SAID PORTION OF THE PIN HAVING LESS EXTERNAL DIAMETER THAN THE