Spindle clamping mechanism

Claim 1

IN A MACHINE TOOL SPINDLE MECHANISM HAVING AN AXIALLY ADJUSTABLE TOOL BAR SUPPORTED IN A ROTATABLE MEMBER, A RELEASABLE CLAMPING MECHANISM FOR SECURING THE TOOL BAR IN AXIAL POSITION IN THE ROTATABLE MEMBER COMPRISING: (A) A SLEEVE FIXED IN SAID ROTATABLE MEMBER AND HAVING A THIN ANNULAR SECTION IN CONTACT WITH THE TOOL BAR AND EXTENDING THEREAROUND, SAID THIN SECTION SPACED FROM THE ROTATABLE MEMBER TO PROVIDE AN ANNULAR CAVITY THEREBETWEEN, (B) A PAIR OF ADJACENT OUTSIDE CYLINDRICAL SURFACES OF DIFFERENT DIAMETERS AND A SHOULDER EXTENDING THEREBETWEEN FORMED ON THE ROTATING MEMBER, (C) AN AXIALLY MOVABLE AND ANNULAR PLUNGER RECEIVED OVER SAID ROTATABLE MEMBER FOR ROTATION THEREWITH AND HAVING ADJACENT INTERNAL CYLINDRICAL SURFACES AND A SHOULDER EXTENDING THEREBETWEEN DISPLACED AXIALLY FROM SAID ROTATABLE MEMBER SHOULDER TO FORM A CHAMBER OF VARIABLE CAPACITY THEREBETWEEN, (D) A COMMUNICATING PASSAGE BETWEEN SAID ANNULAR CAVITY AND SAID VARIABLE CAPACITY CHAMBER, (E) A PRESSURE FLOWABLE SUBSTANCE OF VERY LOW VOLUMETRIC COMPRESSIBILITY FILLING SAID ANNULAR CAVITY, VARIABLE CHAMBER AND COMMUNICATING PASSAGE, (F) A SPRING MECHANISM ON SAID ROTATABLE MEMBER ENGAGED AGAINST SAID ANNULAR PLUNGER AND PRODUCING A BIAS FORCE THEREON TENDING TO MOVE SAID SHOULDER THEREIN INTO CONTACT WITH SAID ROTATABLE MEMBER SHOULDER TO PRESSURIZE SAID PRESSURE FLOWABLE SUBSTANCE TO EXPAND SAID ANNULAR CAVITY AND CLAMP THE TOOL BAR IN AXIAL POSITION IN THE ROTATABLE MEMBER, AND (G) MEANS FOR PRODUCING AND TRANSMITTING A FORCE TO SAID ANNULAR PLUNGER IN OPPOSITION TO SAID BIAS FORCE TO EXPAND SAID VARIABLE CAPACITY CHAMBER AND REDUCE THE PRESSURE THEREIN TO RELEASE SAID TOOL BAR FOR AXIAL ADJUSTMENT IN THE ROTATABLE MEMBER.