A hammer drill having a motor mounted within a body and an output spindle; a tool holder mounted on the body capable of holding a cutting tool; a hammer mechanism having a piston; a reciprocating drive for converting rotary movement of the motor into reciprocating movement of the piston; a ram reciprocatingly driven by the piston via an air spring to strike a cutting tool held in the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use; an air replenishment mechanism capable of refreshing the air spring during certain time periods during normal use; the air replenishment mechanism capable of being adjusted to refresh the air spring during time periods within the hammer cycle and/or the system allows different volumes of air into or out of the air spring during the refreshment time periods.

A hammer drill having a motor mounted within a body and an output spindle; a tool holder mounted on the body capable of holding a cutting tool; a hammer mechanism having a piston; a reciprocating drive for converting rotary movement of the motor into reciprocating movement of the piston; a ram reciprocatingly driven by the piston via an air spring to strike a cutting tool held in the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use; an air replenishment mechanism capable of refreshing the air spring during certain time periods during normal use; the air replenishment mechanism capable of being adjusted to refresh the air spring during time periods within the hammer cycle and/or the system allows different volumes of air into or out of the air spring during the refreshment time periods.

A percussion tool including a parking assembly movable relative to a spindle. The parking assembly includes a seat coupled to the spindle, a first shuttle portion movable relative to an outer surface of the spindle, a biasing member positioned between the seat and the first shuttle portion, a second shuttle portion movable relative to the outer surface of the spindle, a bushing positioned within the spindle and configured to receive a portion of an anvil, and a fastener that couples the second shuttle portion to the bushing. The first shuttle portion and the second shuttle portion are movable together between a working position, in which a plurality of radial air vents in the spindle is closed, and an idle position, in which the plurality of radial air vents is open. The biasing member is configured to bias the first shuttle portion and the second shuttle portion into the idle position.