HAMMER DRILL

A piston for a hammer drill characterized in that the piston (204) is a flat piston made from sintered steel. The piston (204) can be impregnated with a lubricant. A hammer drill may comprise; a housing (2); a tool holder 98) mounted on the housing (2) which is capable of holding a cutting tool (12); a motor (48) mounted within the housing (2); and a hammer mechanism comprising: a cylinder (150); a piston (204) as claimed in any one of claims 1 to 3 wherein the piston (204) is mounted in the cylinder, which is reciprocatingly driven along a longitudinal axis (154) by the motor when the motor is actuated; a ram (152), mounted in the cylinder forward of the piston, which is reciprocatingly driven on the longitudinal axis by the reciprocating piston via an air spring (170); a beat piece (156) supported in an axially slideable manner on the longitudinal axis within a beat piece support structure (150, 210) which, during the normal operation of the hammer mechanism, is repetitively struck by the ram and which transfers the impacts to a cutting tool when held by the tool holder.