Patent ID: 8430181

Claim:
A hammer drill comprising: an outer housing defining at least one handle adapted to be gripped by a user; a transmission housing; a drive mechanism substantially enclosed by the transmission housing for driving a working member of the tool, the drive mechanism having a motor, wherein the transmission housing is moveably mounted in the outer housing for movement of the drive mechanism relative to the outer housing along a non-linear path between a first position within the outer housing, corresponding to no force being applied by a user to the outer housing of the tool, and a second position within the outer housing, such that movement of the transmission housing from the first to the second position occurs by means of the user applying a force to the outer housing when the working member of the tool engages a workpiece; and a biasing member for biasing the drive mechanism towards the first position; wherein a direction of travel of the transmission housing relative to the outer housing at a particular point on the non-linear path is arranged to coincide with a direction of the dominant vibration occurring in the transmission housing relative to the outer housing when a particular force is applied to the outer housing to move the transmission housing relative to the outer housing to that point on the non-linear path against a biasing force of the biasing member.