Powerhead

Claim 1

A POWERHEAD FOR HOLDING WORK PIECE COMPRISING; (A) A CASING ADAPTED TO BE SECURED TO THE WORK SUPPORTING PORTION OF A MACHINE TOOL AND DEFINING A CYLINDRICAL CHAMBER, A PAIR OF FLUID PASSAGE ONE EACH COMMUNICATING WITH AN OPPOSITE END OF SAID CHAMBER, AND AXIAL OPENINGS THROUGH EACH OPPOSITE END THEREOF TO SAID CHAMBER. (B) A CYLINDRICAL DRAWBAR EXTENDING AXIALLY THROUGH SAID AXIAL OPENINGS FOR AXIAL SLIDING MOVEMENTS RELATIVE TO SAID CASING AND KEYED TO SAID CASING AGAINST ROTARY MOVEMENT RELATIVE THERETO, (C) A PISTON CONCENTRICALLY MOUNTED ON SAID DRAWBAR FOR COMMON AXIAL MOVEMENTS THEREWITH WITHIN SAID CHAMBER AND HAVING A SEALING RING SLIDABLY ENGAGING THE CYLINDRICAL WALL OF SAID CHAMBER, (D) SAID PISTON AND DRAWBAR BEING MOVED ALTERNATELY IN OPPOSITE DIRECTIONS AXIALLY OF SAID CHAMBER RESPONSIVE TO INTRODUCTION OF FLUID UNDER PRESSURE ALTERNATELY TO OPPOSITE ENDS OF SAID CYLINDER THROUGH SAID PASSAGES, (E) A GENERALLY CYLINDRICAL WORK PIECE HOLDER EXTENDING AXIALLY OUTWARDLY FROM ONE END OF SAID DRAWBAR AND AXIALLY ADJUSTABLY SECURED AT ITS INNER END TO SAID DRAWBAR FOR COMMON AXIAL MOVEMENTS THEREWITH AND FOR ADJUSTABLE MOVEMENTS AXIALLY OF SAID DRAWBAR, (F) SAID HOLDER BEING LONGITUDINALLY SPLIT AT ITS OUTER END PORTION OUTWARDLY OF SAID CASING TO PROVIDE A PLURALITY OF RADIALLY INWARDLY AND OUTWARDLY MOVABLE GRIPPING ELEMENTS YIELDINGLY BIASED IN ONE DIRECTION OF RADIAL MOVEMENT THEREOF, (G) AN ACTUATOR ELEMENT MOUNTED ON SAID CASING AND ENGAGING SAID MOVABLE GRIPPING ELEMENTS TO IMPART MOVEMENTS THERETO IN A DIRECTION AGAINST SAID YIELDING BIAS RESPONSIVE TO AXIAL MOVEMENT OF SAID PISTON AND DRAWBAR IN ONE DIRECTION, (H) INDEPENDENT MEANS OPERATIVELY CONNECTING SAID ACTUATOR ELEMENT TO SAID WORK PIECE HOLDER FOR IMPARTING ADJUSTING MOVEMENT TO SAID HOLDER RELATIVE TO SAID DRAWBAR, AND (I) MEANS FOR RELEASABLY LOCKING SAID ACTUATOR ELEMENT AGAINST MOVEMENTS IN DIRECTIONS TO ADJUST SAID WORK PIECE HOLDER.