Valve actuators and combined valves and actuators

In combination, a valve including a stem extending outwardly of the valve body, an arm secured to the stem, and said body provided with a pair of spaced stops limiting the turning of the stem to predetermined opened and closed positions, and an actuator including a body having a cylindrical chamber, a rotor extending diametrically through said chamber and spaced from the ends thereof, said rotor including a lengthwise series of teeth within said chamber, at least one piston within said chamber, said piston provided with a sealing ring and including an integral skirt with inner and outer segmental portions, the chordal face of said outer skirt portion being provided with a series of transverse teeth meshing with said rotor teeth and the opposite surface of said skirt including a plurality of circumferential spaced sockets adjacent and spaced in said outer skirt portion, a plurality of anti-friction buttons being press-fitted in each of said sockets, said buttons being solely positioned along the centerline of said transverse teeth, and the macimum cross-sectional area of said buttons being less than the length of said transverse teeth, and said body including two passageways, each for use in the delivery or relief of air, both passageways opening through the same end of the body, one passageway in communication with said chamber on the side of said one piston opposite said skirt and the other in communication with said chamber on the other side of said one piston and the chordal face of the skirt, and means operable to clamp said valve to said actuator with said stops and arm exposed, one end of said rotor exposed in the form of a fork gripping said arm so that one passageway is for use in effecting the turning of the rotor in a valve opening direction and the other passageway for use in turning the rotor in a valve closing direction.