If what we are calling here a servo motor was a true servo motor, it would have constant torque throughout the entire speed range. True servos are used for precise indexing and positioning applications in industry.
The servos used on sewing machines are not true servos, so you are right that there is more mechanical advantage ( torque ) at lower speeds, and less at higher speeds.
No one lives forever, the trick is creating something that will.
Last edited by DanTwoLakes; 01-29-2013 at 11:02 AM.