Automatic throttle torque-responsive power tool

Claim 1

A power-operated tool comprising: a rotary motor; supply means for conducting motor-driving energy to said motor; control means having alternate positions and controlling said supply means so that in one position it prevents said energy from being supplied to said motor, and in its other position, it allows said energy to flow to said motor, said control means being normally in said one position and including biasing means urging said control means to said one position, a tool spindle adapted to be connected to a workpiece for applying a torque load to the workpiece and operative, when pressed against the workpiece, to move said control means to its other position; a torque-responsive clutch which is normally closed to interconnect said spindle to said motor, said clutch being operative, in response to a predetermined torque load on said spindle, to open wherein said motor can rotate relative to said spindle, said clutch including a clutch member that moves axially when said clutch opens; a spring located between said spindle and said control means and operative, in its normal position, when said clutch is closed and said spindle is pressed against a workpiece, to transmit force from said spindle to said control means to urge and hold said control means in its other position, said clutch member being operative, when moving axially during the opening of said clutch, to cause said spring to yield to an inoperative position wherein said spring no longer holds said control means in its other position; and lock means movable in response to the opening of said clutch to hold said spring in said inoperative position wherein said control means can return to said one position preventing said motor-driving energy from flowing to said motor.