Loading the Bobbin and Checking Tension

Intermittent Tension

This first tension device is used to add tension to the top thread. The tension is needed to prevent slack in the thread as the take-up lever moves down. The take-up lever moves up to pull out any slack in the top thread as the stitch is completed. The intermittent tension consists of a thread guide just before it and two symmetrical discs. The thread runs between the two discs and the tension is adjusted by a knob that moves the discs closer or farther apart to create or reduce tension on the thread.

The intermittent tension is the tension adjustment device for the top thread. Tightening or loosening the pressure between the two discs adjusts the tension.