Method of and apparatus for actuating double-acting rotatable clamping means, especially for working spindles

Claim 1

A DOUBLE-ACTING CLAMPING CYLINDER PISTON ARRANGEMENT FOR ROTATABLE WORKING SPINDLES OF MACHINE TOOLS, WHICH INCLUDES: A CYLINDER, A DOUBLE-ACTING PISTON RECIPROCABLE IN SAID CYLINDER AND HAVING A FIRST SIDE AND A SECOND SIDE, A ROTATABLE MEMBER CONNECTED TO SAID CYLINDER AND PROVIDED WITH FIRST AND SECOND PASSAGE MEANS RESPECTIVELY COMMUNICATING WITH SAID FIRST AND SECOND SIDE, A STATIONARY TUBULAR MEMBER SURROUNDING SAID ROTATABLE MEMBER IN RADIALLY SLIGHTLY SPACED RELATIONSHIP THERETO SO AS TO CONFINE WITH SAIS ROTATABLE MEMBER A RELATIVELY NARROW ANNULAR GAP, SAID TUBULAR MEANS HAVING ITS INNER PERIPHERY PROVIDED WITH AXIALLY SPACED FIRST AND SECOND ANNULAR GROOVE MEANS ARRANGED WITHIN THE RANGE OF SAID ANNULAR GAP, SAID FIRST AND SECOND ANNULAR GROOVE MEANS RESPECTIVELY COMMUNICATING WITH SAID FIRST AND SECOND PASSAGE MEANS, FIRST AND SECOND CHECK VALVE MEANS RESPECTIVELY INTERPOSED IN SAID FIRST AND SECOND PASSAGE MEANS AND OPERABLE TO OPEN IN RESPONSE TO A CERTAIN PRESSURE MEANS THE RESPECTIVE GROOVE MEANS, FIRST CONTROL MEANS INTERPOSED BETWEEN SAID CHECK VALVE MEANS AND MOVABLE FROM A CENTRAL POSITION TO A FIRST END POSITION AND AN OPPOSITELY LOCATED SECOND END POSITION IN RESPONSE TO A CERTAIN MINIMUM PRESSURE IN SAID FIRST AND SECOND GROOVE MEANS RESPECTIVELY TO OPEN THAT ONE OF SAID CHECK VALVES WHICH IS ASSOCIATED WITH THE RESPECTIVE PISTON SIDE TO BE VENTED, SECOND CONTROL MEANS OPERATIVELY CONNECTED TO SAID FIRST AND SECOND GROOVE MEANS AND OPERABLE TO VENT SAID FIRST AND SECOND GROOVE MEANS WHEN SAID PISTON HAV COMPLETED ITS CLAMPING STROKE TO THEREBY CAUSE BOTH OF SAID CHECK VALVES TO CLOSE AND A VENTING BORE INTERMEDIATE SAID GROOVES CONTINUOUSLY VENTING THE RADIAL SPACE BETWEEN SAID TUBULAR MEMBER AND SAID ROTATABLE MEMBER AT A POINT THEREALONG BETWEEN SAID GROOVES TO THE ATMOSPHERE.