US Patent 10003135 Mechanical use-limiting connector for electrical tool

Disclosed herein is a use-limiting connector for limiting use of an electrical tool. The use-limiting connector includes an electrical circuit, a plunger, movable between a first position and a second position, and a biasing member, configured to urge the plunger into the first position and configured to incrementally uncoil into respective torsional states as the plunger moves between the first position and the second position. With the plunger in the first position and the biasing member in a first one of the torsional states, the biasing member closes the electrical circuit. As the plunger moves from the first position to the second position, the plunger moves the biasing member to open the electrical circuit.