Abstract: A pneumatic rotating tool is disclosed wherein the amount of air discharged is adjusted with a finger of the hand which holds the tool, thereby making it possible to adjust the rotational speed of the air motor incorporated in the tool. Rotation of a cylindrical regulator relative to a cylindrical housing is limited to an angle through a predetermined range centered on an axis of the cylindrical housing. The regulator is formed with a cutout portion and a depression both for opening exhaust holes formed in the motor body. The regulator is further formed with thick-wall portions for closing the exhaust holes.

Abstract: To provide a rotational speed adjusting device for a pneumatic rotational tool in which even if high air pressure is supplied, rotational frequency thereof does not exceed the maximum allowable rotational frequency so as to prevent occurrence of breakage of a processing tool. A speed adjusting shaft 30 is secured to one end of a rotor 26, and a speed adjusting member 32 capable of being displaced with respect to the speed adjusting shaft 30 is mounted externally of the speed adjusting shaft 30. The speed adjusting shaft 30 is provided with a ball 44 movable in a radial direction, and the speed adjusting member 32 is axially displaced with respect to the speed adjusting shaft 30 by a centrifugal force applied to the ball 44.