Pressure clamps for ring-like workpieces

Claim 1

IN A MACHINE FOR GRINDING THE EXTERNAL PERIPHERAL SURFACES OF RING-LIKE WORKPIECES, A ROTATABLE FACE PLATE TO DRIVE A WORKPIECE, MEANS MOUNTED INDEPENDENTLY OF SAID FACE PLATE FOR HOLDING A WORKPIECE AGAINST SAID FACE PLATE COMPRISING AN ARBOR MOVABLE AXIALLY RELATIVE TO SAID FACE PLATE AND HAVING MEANS FOR ENGAGING THE END SURFACE OF SAID WORKPIECE, A CYLINDER ENCLOSING THE END OF SAID ARBOR, A PISTON IN SAID CYLINDER FOR URGING SAID ARBOR IN THE DIRECTION OF A SAID FACE PLATE, PERIPHERALLY SPACED SHOES FOR ENGAGING SAID EXTERNAL PERIPHERAL SURFACE SO THAT SAID WORKPIECE MOVES RADIALLY AS IT BECOMES SMALLER IN DIAMETER, MEANS TO INTRODUCE FLUID UNDER PRESSURE BETWEEN SAID PISTON AND SAID ARBOR SO THAT SAID ARBOR HOLDS SAID WORKPIECE AGAINST SAID FACE PLATE BY FLUID PRESSURE RATHER THAN BY SPRING PRESSURE OF SAID PISTON AND, SO THAT SAID ARBOR ROTATES WITH SAID WORKPIECE, FREE OF CONTACT WITH SAID PISTON, THE RELATION BETWEEN SAID CYLINDER DIAMETER AND SAID ARBOR DIAMETER BEING SUCH AS TO PERMIT LIMITED RADIAL MOVEMENT OF SAID ARBOR IN ORDER FOR SAID ARBOR TO MOVE WITH SAID WORKPIECE AS THE RADIAL POSITION OF SAID WORKPIECE CHANGES DUE TO CHANGE IN ITS DIAMETER FROM GRINDING.