Powered hand hammer

Claim 1

A POWER HAMMER COMPRISING: AN ELONGATED HEAD HOUSING; A PLUNGER JOURNALLED IN THE HOUSING FOR LONGITUDINAL RECIPROCATING MOVEMENT THEREIN AND SPRING-BIASED IN THE DIRECTION FROM A WITHDRAWN TO AN EXTENDED POSITION; A TOOL HEAD MEMBER JOURNALLED COAXIALLY WITH THE PLUNGER FOR LIMITED LONGITUDINAL RECIPROCATING MOVEMENT IN THE HOUSING AND HAVING A PORTION NORMALLY PROJECTING FROM ONE END OF THE HOUSING, SAID MEMBER BEING SPRING BIASED TOWARD A NORMAL POSITION SO AS TO BE STRUCK BY THE PLUNGER WHEN IT MOVES SUBSTANTIALLY HALF WAY FROM ITS WITHDRAWN TO ITS EXTENDED POSITION AND BEING MOVABLE AGAINST THE BIAS OF ITS SPRING WHEN STRUCK BY THE PLUNGER; THE PLUNGER HAVING A TRANSVERSE FLAT SURFACE HAVING A GROOVE THEREACROSS; A ROTATING ELEMENT JOURNALLED IN THE HOUSING AND HAVING A FACE ABUTTING THE PLUNGER FLAT SURFACE; A DRIVE PIN ECCENTRICALLY MOUNTED ON THE ELEMENT AND PROJECTING FROM ITS FACE INTO THE PLUNGER GROOVE; A HOLLOW HANDLE PROJECTING LATERALLY FROM THE HEAD HOUSING; AND MEANS IN THE HANDLE FOR ROTATING SAID ELEMENT; THAT PORTION OF THE GROOVE CARRYING THE PIN DURING THE MOVEMENT OF THE PLUNGER FROM ITS WITHDRAWN TO ITS EXTENDED POSITION BEING OF A WIDTH SUBSTANTIALLY EQUAL TO THE DIAMETER OF THE PIN AND THE REMAINING PORTION OF THE GROOVE BEING WIDER FOR ALLOWING THE PLUNGER TO REBOUND INDEPENDENT OF THE HOUSING DURING THE RETURN OF THE PLUNGER TO ITS WITHDRAWN POSITION.