Axial piston hydraulic units

Claim 1

IN AN AXIAL PISTON HYDRAULIC UNIT OF THE TYPE INCLUDING A CASING, A ROTATABLE CYLINDER BLOCK WITHIN THE CASING, SAID CASING HAVING A PLURALITY OF PISTON ACCOMMODATING BORES EXTENDING PARALLEL TO THE AXES OF ROTATION OF SAID CYLINDER BLOCK, A PISTON RECIPROCABLY DISPOSED IN EACH OF SAID BORES, EACH HAVING A PISTON AND EXTENDING OUTWARDLY FROM SAID CYLINDER BLOCK, SWASH PLATE MEANS MOUNTED IN SAID CASING POSITIONED TO OPERATE SAID PISTONS UPON RELATIVE ROTATION OF SAID CYLINDER BLOCK AND CASING, SAID SWASH PLATE MEANS BEING PROVIDED WITH AN APERTURE INCLUDING THE EXTENSION OF THE AXIS OF ROTATION OF SAID CYLINDER BLOCK, A ROTATABLE SHAFT DRIVINGLY SECURED TO SAID CYLINDER BLOCK ADJACENT SAID SWASH PLATE EXTENDING OUTWARDLY OF SAID CASING THROUGH SAID APERTURE IN SAIS SWASH PLATE, MEANS OPERATIVELY SECURED TO EACH PISTON END TO MAINTAIN SAID PISTON ENDS IN A COMMON PLANE, SAID CYLINDER BLOCK HAVING AN END FACE REMOTE FROM SAID SWASH PLATE CONSTITUTING A DISTRIBUTION END, PORTS LEADING INWARDLY TOWARD THE AXIS OF ROTATION OF SAID CYLINDER BLOCK FROM EACH OF SAID PISTON ACCOMMODATING BORES TO SAID DISTRIBUTION END SO THAT SAID PORTS AT SAID DISTRIBUTION END ARE CLUSTERED CLOSELY ABOUT THE AXIS OF ROTATION OF SAID CYLINDER BLOCK, A TIMING PLATE HAVING A FIRST FACE IN FACE-TO-FACE CONTACT WITH SAID DISTRIBUTION END OF SAID CYLINDER BLOCK AND A SECOND FACE PARALLEL TO SAID FIRST FACE, THE IMPROVEMENT COMPRISING SAID TIMING PLATE HAVING TWO KIDNEY-SHAPED OPENINGS IN SAID FIRST FACE OPENING TOWARD SAID CYLINDER BLOCK OPPOSITE SAID PORTS IN SAID DISTRIBUTION END OF SAID CYLINDER BLOCK, FOUR BORES EXTENDING INTO SAID TIMING PLATE FROM SAID SECOND FACE, SAID FOUR BORES BEING CLUSTERED CLOSELY ADJACENT THE EXTENSION OF THE AXIS OF ROTATION OF SAID CYLINDER BLOCK, SAID FOUR BORES FORMING A PAIR OF INLET BORES AND A PAIR OF OUTLET BORES, EACH PAIR OF SAID BORES JOINING ONE OF SAID TWO KIDNEY-SHAPED OPENINGS TO FORM INLET AND OUTLET PASSAGES THROUGH SAID TIMING PLATE, SPRING MEANS TO HOLD SAID TIMING PLATE AGAINST SAID CYLINDER BLOCK AND SHOULDER MEANS PRESENTED TOWARD SAID FOUR BORES WHEREBY PRESSURES AT SAID FOUR BORES WILL PRESS SAID TIMING PLATE TOWARD SAID CYLINDER BLOCK, SAID FIRST FACE OF SAID TIMING PLATE BEING PROVIDED WITH AN ANNULAR GROOVE OUTWARDLY OF SAID KIDNEY-SHAPED OPENINGS AND HAVING SPACED RADIAL GROOVES EXTENDING OUTWARDLY FROM SAID ANNULAR GROOVE TO THE EDGE OF SAID FIRST FACE.