is more easily illustrated in fig5 and 7 a photocell 82 mounted by a bracket 81 onto a housing of the motor 60 operates in conjunction with a shroud member 84 referred to as a flag mounted on the pulley 62 for rotation therewith to sense a revolution of pulley 62 the photocell 82 comprises a spaced apart emitter and sensor disposed in u shaped fashion relative to the flag 84 such that an outer portion 84a of the flag 84 obstructs the line of site between the emitter and the sensor as the flag rotates past the photocell 82 in the embodiment shown the photocell 82 is mounted to point directly at the center of the pulley 62 the photocell 82 senses the angular position of the flag 84 when the flag 84 is in line with photocell 82 the photocell 82 detects the flag 84 to begin rotation the motor 60 receives a signal from a controller the pulley 62 rotates the flag 84 from the line of sight of the photocell 82 and the pulley 62 makes one rotation until the flag 84 passes through the line of sight of photocell 82 thus signalling the controller to stop motor 60 the motor 60 then coasts to a stop after about 45 degrees of rotation as is generally illustrated in fig5 an alternative embodiment may utilize an alternative switch mechanism such as a microswitch and a cam projection on the pulley 62 for informing the controller when to stop the motor 60 this operation may be more easily understood by comparing fig5 and 7.