Production assembly tool

An electrically powered tool for driving a fastener to a predetermined torque level including a housing, a motor disposed within the housing for rotatably driving an output spindle journalled with respect to the housing and adapted for drivingly engaging the fastener, a clutch disposed between the motor and the output spindle and movable in response to the torque applied to the output spindle attaining said predetermined torque level from an engaged position wherein torque from the motor is applied to the output spindle to a disengaged position wherein torque from the motor is not substantially applied to the output spindle, and a clutch switch operatively associated with the clutch and responsive to movement of the clutch for switching from a first state when the clutch is in the engaged position to a second state when the clutch is in the disengaged position;

• the improvement comprising a control circuit for controlling the energization and braking of the motor, the control circuit including a RUN circuit connected to the motor and adapted when enabled to energize the motor, a BRAKE circuit connected to the motor and adapted when enabled to dynamically brake the motor, a logic circuit connected to said RUN circuit and BRAKE circuit for controlling the enabling of said RUN circuit and BRAKE circuit, and a monitor circuit connected to said clutch switch for monitoring the position of said clutch switch, said monitor circuit providing a first signal to said logic circuit after the clutch switch has remained in said first state for a first predetermined period of time and a second signal when said clutch switch is in said second state;
• said logic circuit being operative to disable said RUN circuit and enable said BRAKE circuit in response to the receipt from said monitor circuit of said second signal only when preceded by the receipt from said monitor circuit of said first signal.