The drive mechanism for a paper tape punch and reader assembly utilizes tape drive assemblies which move the paper tape in response to the application of continuous periodic motion and control signals. The periodic motion serves to oscillate a rocker plate between first and second limits and the control signls serve to selectively engage and disengage a detent which effects coupling between the drive shaft and the source of periodic motion. The periodic motion is imparted to the drive assembly by a connecting link which in turn is driven by an adjustable eccentric.
The eccentric comprises a pulley plate which is fixed to a shaft. A circular body is adjustably movable with respect to the pulley plate and is arranged to engage the race of a ball bearing assembly which further comprises balls and a retaining ring. The connecting link has a circular opening which provides a snug fit to the exterior of the retaining ring. The pulley plate and the body are held in a fixed physical relation by two locking screws and the relative position of the two is established by an eccentric which is mounted on one of the locking screws.
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