Posted by BillS on May 15, 2008 at 16:40:47:
In Reply to: worm gear & shaft posted by MKK on May 14, 2008 at 21:25:31:
You're right about the normal expectation that it is hard or impossible to backdrive the worm - This is usually part of the design - since it doesn't require a brake to hold the torque load attached to the wormgear. This ability is primarily due to the high ratio (e.g. 20:1 in your example).
If the ratio was say, 5:1 (a 4 start worm) maybe backdriving would be practical, but I doubt that a motor driving the wormgear would be a good idea.
I dunno, it just seems to me that all the good things about a worm drive are negated by applying it this way. Why does the customer want to do this? Is he looking for a speed increaser with right angle / offset drive?