Overspeed saftey control mechanism for rotary tools

In a tool as in claim 2, wherein a yieldable gate normally restrains the ball valve in the hole against release therefrom by centrifugal forces of less than said certain value.

A surface grinding tool including a rotary air motor having a rotor shaft, an inlet port for admitting operating air to drive the motor, a circular body carried by the shaft disposed in coaxial relation to the latter and having a radial hole in its periphery, a ball valve received in the hole, a yieldable gate releasably retaining the ball valve in the hole, the ball valve being adapted to be centrifugally forced from the hole through the gate upon the motor developing a certain degree of speed and adapted when so released to enter the inlet port in closing relation to the latter, and means fitted in the inlet port for retaining the ball valve in said closing relation.

A surface grinding tool, including a rotary air motor having a rotor shaft adapted to carry a surface grinding wheel, a circular body carried by the shaft in coaxial relation thereto and having a radial hole in its periphery, a passage for conducting live air to operate the motor, a first valve controlled port arranged intermediately of the passage, speed responsive governor controlled valve means carried by the rotor shaft for regulating air flow through the first port, a normally open second valve controlled port disposed in the passage between the first port and the motor, and a ball valve slidably received in the hole of the circular body, the ball valve being centrifugally movable out of the hole upon development of centrifugal forces of a certain value by the motor, track means for receiving the ball valve when thus released and guiding it into closing relation with the second port, and means fitted in the second port for retaining the ball valve in said closing relation.