Abstract: An apparatus for connection to a periodic, pulsed air supply for providing an indication of time based on receipt of the air pulses comprises a rotor having an externally visible pointer. The rotor is mounted in a cylindrical housing and includes a first section which moves axially of the housing under the force of an air pulse. Teeth are formed on the rotor first section which coact with stationary teeth mounted on the housing interior to force the rotor first section to rotate a predetermined amount. This rotation is transmitted to a second axially stationary rotor section by a keyed connection between the rotor sections. The axially movable section is forced to its original position by a spring mounted in the housing.

Abstract: This clock consists primarily of a main body to which is attached an air connection, on one end. Within the main body is a toothed piston rotor with spaced-apart indentations that removably receive a pair of drive screws in the base of the main body. The piston rotor is spring loaded on a central shaft, and a toothed cap is pinned in the bore of the main body. When air enters the main body, the piston rotor, the shaft and the hour hand are forced up, and the teeth turn this unit twenty-two degrees. When the air is turned off, the spring returns this unit to the base and forces the unit onto the drive screws of the main body, which turns the unit another eight degrees. This cycle advances the hour hand one hour, which is indicated by means of the radially spaced drive screws in the toothed cap.