Patent ID: 7607491

Claim:
A lift assist device for attachment to a percussion power tool to facilitate lifting and extraction of the percussion power tool, the lift assist device comprising: a) a top cylinder; b) a bottom cylinder; c) a cylinder wall connected to and between the top cylinder and the bottom cylinder, wherein the top cylinder and the bottom cylinder when connected to the cylinder wall form a continuous vertical cylindrical body with an upper lifting chamber and a lower retracting chamber; d) a control unit operably associated with the top cylinder, wherein the control unit further comprises a control valve operable by a lever, wherein the control valve has at least an actuated position and a normal position that control flow of actuating media through an inlet port and a first outlet port, wherein the inlet port is operably connected to a source of pressurized actuating media, and wherein the first outlet port is operably connected to the upper lifting chamber; e) a lifting foot unit vertically aligned with the cylindrical body, the lifting foot unit comprising a piston, a lifting foot and a piston rod connected to and between the lifting foot and the piston, wherein the piston rod extends through an opening in the bottom cylinder, and wherein the piston separates the upper lifting chamber from the lower retracting chamber; and a piston retractor arranged to provide a force against the piston and maintain the piston in an upward direction away from the bottom cylinder towards the top cylinder to thereby keep the lifting foot maintained in a retracted position when the control valve is in the normal position; wherein actuation of the control valve, releases said force against the piston to push the piston down with the piston rod and lifting foot against the working surface to raise the percussion power tool from the working surface, thereafter switching the control valve to the normal position to force the piston rod and lifting foot back to the upward and maintained retracted position, thus returning the percussion power tool to the working surface.