Shut-off apparatus for pneumatic driven tools

An improved torque-responsive, shut-off apparatus for pneumatically driven tools that include an air motor driving a rotatable output shaft arranged to rotate a tool rotatably driven by said output shaft, an air supply and a main valve located in an air supply passageway for controlling air flow from the air supply to the motor, the improvement comprising:

• a shut-off valve located between the main valve and the motor, said valve including a valve seat encircling the air supply passageway, a valve member fitting relatively closely in the air supply passageway, said valve member being movable into and out of engagement with said valve seat to close and open said valve, respectively, and an elongated valve control member having a first end connected to said valve member and having a second end extending partially through said output shaft;
• governor means mounted for rotation with the output shaft and including latch means slideable relative to said output shaft and engageable with the second end of said control member to hold said valve member away from said seat and inertia responsive means movable relative to said shaft for releasing said latch means permitting said valve member to move into engagement with said seat closing said shut-off valve and stopping the tool when said air motor slows in response to a pre-determined torque being imposed on said output shat;
• and,
• said inertia responsive means includes a weighted member having its centroid spaced from the axis of the output shaft and said governor means also includes a second weighted member fixed against movement relative to the output shaft having a centroid located to balance said first mentioned weighted member.