Originally Posted by
Macybaby
As to what it does - it is the tension control for the upper thread, so it is required to be able to sew.
Most of them have a means to disengage the tension, that is what the "lever" does. So you'd push it down to pull your sewing away from the needle.
Thanks for all of the pictures of the different tensions. I found that very interesting as well as the explanation of the lever. I know it takes time to get good photos and load them up here and I sure do appreciate it!