US Patent 6883617 Air auto shut-off

An automatic shutoff mechanism is designed for a pneumatic tool having an air motor, a pressurized airflow path to the motor and a torquing mechanism driven by the motor. The shutoff mechanism includes a valve member moveable between open and closed positions relative to the airflow path and biased to the open position. A trip apparatus is responsive to application of a predetermined torque for moving the valve member to a trip position disposed in the airflow path sufficiently to expose the valve member to the pressurized airflow for driving the valve member from the trip position to the closed position. Mechanical and electromechanical embodiments are disclosed.