Impact drill

Claim 1

IN COMBINATION WITH A DRILL BIT OF THE TYPE HAVING A CYLINDRICAL SHOULDER ABUTTING A SHANK, OF SMALLER DIAMETER THAN THE SHOULDER, AND OF NON-CIRCULAR CROSS-SECTION, A ROTARY HAMMER DEVICE, COMPRISING, A HOUSING HAVING A BORE THERETHROUGH; A CYLINDRICAL BEARING BLOCK IMMOVABLY MOUNTED WITHIN THE HOUSING BORE, INTERMEDIATE THE ENDS THEREOF, THE BLOCK HAVING ANNULAR END FACES AND AN AXIAL BORE THERETHROUGH; A TWO HEADED PLUNGER MOUNTED IN THE HOUSING FOR ROTARY AND AXIAL MOVEMENT, THE PLUNGER HAVING A CYLINDRICAL HAMMER HEAD AT ITS FORWARD END AND A CYLINDRICAL CLUTCH HEAD AT ITS REAR END, SPACED APART A DISTANCE GREATER THAN THE WIDTH OF THE BEARING BLOCK AND JOINED THROUGH A SHAFT PORTION OF REDUCED DIAMETER, JOURNALED IN THE BEARING BLOCK, WITH THE HEADS POSITIONED ON OPPOSITE SIDES THEREOF; EACH OF THE HEADS HAVING AN ANNULAR CAM SURFACE FACED TOWARD THE ADJACENT BEARING BLOCK ANNULAR END FACE, THE PLUNGER ALSO HAVING AN AXIAL BORE THERETHROUGH ADAPTED TO RECEIVE AND HOLD THE NON-CIRCULAR DRILL SHANK IN FREELY SLIDABLE BUT NON-ROTATABLE ENGAGEMENT; SLIDABLE COUPLING MEANS ON THE CLUTCH HEAD FOR CONNECTING THE PLUNGER TO A ROTARY DRIVING MEMBER MOUNTED ON THE HOUSING AND HELD AGAINST AXIAL MOVEMENT; THE HAMMER HEAD HAVING AN ANNULAR STRIKER FACE AT THE FORWARD END THEREOF SURROUNDING THE PLUNGER BORE, AND ADAPTED TO SEAT AGAINST THE CYLINDRICAL SHOULDER OF THE DRILL SHANK POSITIONED IN THE PLUNGER BORE; CO-OPERATING CAM MEANS ON SAID PLUNGER AND BEARING BLOCK FOR IMPARTING RECIPROCATING AXIAL MOVEMENT TO THE PLUNGER WHEN THE PLUNGER IS ROTATED IN THE HOUSING, SAID CO-OPERATING CAM MEANS COMPRISING A PLURALITY OF CIRCULARLY ARRANGED STATIONARY CAMMING PORTIONS ON BOTH ANNULAR END FACES OF THE BEARING BLOCK AND A PLURALITY OF CO-OPERATING CIRCULARLY ARRANGED CAMMING PORTIONS ON THE HAMMER AND CLUTCH HEAD SURFACES FACED TOWARD THEIR RESPECTIVE BEARING BLOCK END FACES, THE CAMMING PORTIONS ON THE HAMMER HEAD BEING DISPLACED CIRCUMFERENTIALLY RELATIVE TO THOSE ON THE CLUTCH HEAD, WHEREBY, UPON ROTATION, THE PLUNGER HAMMER HEAD IS MOVED AXIALLY BETWEEN A FIRST, RETRACTED POSITION WHEREIN THE HAMMER HEAD IS PROXIMATE THE BEARING BLOCK WHEN THE CAMMING SURFACES ON THE CLUTCH HEAD AND BEARING BLOCK ARE ENGAGED, AND A SECOND, ADVANCED, POSITION WHEREIN THE HAMMER HEAD IS SPACED FORWARDLY OF AND AWAY FROM THE BEARING BLOCK, WHEN THE CAMMING SURFACES ON THE HAMMER HEAD AND BEARING BLOCK ARE ENGAGED, TO IMPACT FREELY AGAINST THE DRILL BIT COLLAR.