A hammer drill and method

A hammer drill comprising: a body (2); a cylinder (58) mounted within the body (2); a piston (60) slideably mounted within the cylinder (58); a motor (24) mounted within the body (2) having an output spindle (30); a reciprocating drive mechanism mounted within the body which, when the motor is activated, converts the rotary movement of the spindle (30) of the motor (24) into a reciprocating movement of the piston (60) within the cylinder (58); a ram (64) slideably mounted within the cylinder (58) which is reciprocatingly driven by the reciprocating movement of the piston (60) via an air spring (62); at least two air entry points (200, 202) formed through the wall of the cylinder (58) in different axial positions along the length of the cylinder (58), each of which are capable of replenishing the air spring (62); a tool holder (14) mounted on the body, the tool holder being capable of holding a cutting tool (22) which, during normal use, is repetitively struck by the reciprocating ram (64); wherein there is further provided a selector mechanism (204) which selectively opens and close the air entry points (200, 204); characterized in that the selector mechanism opens only one air entry point (200, 202) at any one time during normal use, the selector mechanism closing all other air entry points (200, 202), each of the air entry point (200, 202) capable of replenishing the air spring (62) during normal use when opened by the selector mechanism (204).