Abstract: The present invention comprises a combined speed sensor and control valve for a rotary fluid motor such as a rotary vane air motor. Weights are pivotally attached to the opposite sides of the rotating output shaft of the air motor and are spring biased into engagement with an annular valve disc member positioned over the air inlet. Upon excessive speed of the shaft, the weights swing from engagement with the valve disc member and release the member. Air flow and air pressure within the air inlet passage cause the disc member to translate axially along the rotary shaft and close the air inlet. The air motor must be disassembled and the overspeed control reset prior to continued operation of the air motor.