Abstract: A governor device for rotary grinders and the like is disclosed. The device prevents the dangerous overspeed of the grinder by throttling air to the motor as the grinder speed approaches overspeed. Throttling action is accomplished by means of allowing a resilient split ring or segment to expand radially out against air inlet orifices by means of centrifugal force. The split ring is assisted outwardly by means of an auxiliary mass means disposed within radially extended slots of an internal cage means.

Abstract: This invention relates to power tools and more particularly to an air-operated power tool commonly used for automotive or other assembly operations for installing threaded fasteners. The device of this invention shuts off the power tool as it approaches the stall condition. Motor rotation is sensed by transferring a small mass of air in proportion to the speed of the motor but independent of the air expanded to operate the motor. The air transferred is utilized to create a signal which through an air-operated valve shuts the power tool off when the speed is reduced below a predetermined amount as when the torquing cycle is nearing completion.