Feeding and propelling system for the tape in a seed-tape manufacturing machine

摘要

A seed-tape manufacturing machine having a main drive for pulling the tape past a seed-dispenser and an auxiliary drive for positively unwinding a drum-like cylinder to tape through peripheral contact means that engage the drum's periphery. The auxiliary drive comprises a variable speed DC motor, with a potentiometer controlling its speed. The resistance of the potentiometer is changed by rotation of a shaft which carries a pinion gear in mesh with a larger gear on another shaft, and this other shaft is supported by a beam that is pivotally mounted on the axis of that shaft. At an outboard end of the beam is a movable portion of a guide-and-tension means via which the unwinding tape is fed to the main tape driving means. When the speed of unwinding and the speed of the main drive differ somewhat, the beam is swung up or down about its pivot, in order to maintain a substantially constant tape tension at the guide-and-tension means. This results in changing the resistance of the potentiometer and thereby the voltage to the DC motor, and therefore in varying the motor's speed in such a way as to compensate for the change and to tend to restore the two drives to equilibrium.