Patent ID: 7712554

Claim:
A down-the-hole hammer drill including an improved drill bit and chuck assembly, the hammer drill comprising: a wear sleeve or housing having a rear end and an opposed forward end and having a reciprocable piston received therein, the reciprocable piston having an impact end; a chuck received within the forward end of the wear sleeve or housing, the chuck being adapted for insertion into the wear sleeve or housing via the rear end thereof, the chuck being externally splined and the wear sleeve or housing being internally splined, the splines of the chuck and the wear sleeve or housing engaging to enable reciprocal motion of the chuck within the wear sleeve or housing; a drill bit having a head at its forward end and a shank extending from the head, the shank defining a striking face at its free end and the drill bit being threadedly received within the chuck such that the striking face of the drill bit is in opposed striking relationship with the impact end of the piston; wherein the drill hammer further comprises means for retaining the chuck within the wear sleeve or housing when the impact end of the piston impacts onto striking face of the drill bit, in use; and the impact end of the piston being adapted to impact onto the striking face of the drill bit without impacting the chuck.