Hammer assembly

A hammer assembly comprising:

• a housing having opposing ends and an internal passage extending between said open ends, said passage including a forward portion adjacent one end of said housing and a rearward portion adjacent the other end of said housing, said forward and rearward portions each being substantially uniform in cross-sectional area along the longitudinal axis of said housing, said cross-sectional area of the forward portion being less than said cross-sectional area of the rearward portion;
• a hammer element positioned in said housing for reciprocal movement in said passage between forward and rearward positions, said hammer element having an opening formed therein;
• a biasing member positioned in said opening and capable when enabled of biasing said hammer element in the direction of its rearward position, said biasing member comprising a helically wound spring compressed when not enabled between a pair of opposing walls of said hammer element defining the forward and rearward ends of said opening, said spring having a diameter greater than said cross-sectional area of the forward portion of said passage and less than said cross-sectional area of the rearward portion of said passage;
• and
• means for enabling said spring when said hammer element is in at least its forward position, said means for enabling comprising wall means forming part of said housing and being located substantially at the boundary of the forward and rearward portions of said passage for engaging one end of said spring and preventing its movement toward the end of said housing adjacent the forward portion of said passage whereby continued forward movement of said hammer element causes said spring to be further compressed between said wall means at said one end of said spring and one of said pair of opposing walls at the other end of said spring thereby biasing said hammer element in a rearward direction.