11-02-2014, 05:39 PM
(This post was last modified: 11-02-2014, 05:47 PM by Alan Douglas.)
For the usual repulsion-induction motor, there is a centrifugal mechanism to short-circuit all the commutator bars, to make the rotor a squirrel-cage. Normally the brushes also lift, to reduce wear, but they don't have to. In a straight repulsion motor they are always in contact. The fact that the operating the brush-shift has no effect while running, suggests the commutator is shorted and the brushes aren't doing anything during that time.
Small lathes here commonly have threaded chucks and they always reverse. I wouldn't take a heavy cut in reverse, but I've never had any problem with the chuck coming loose. My Logan has a 2 1/4-8 thread, I recall, and takes 5C collets natively. It came with a three-phase motor which can be reversed "on the fly" though I changed it to single-phase.
Small lathes here commonly have threaded chucks and they always reverse. I wouldn't take a heavy cut in reverse, but I've never had any problem with the chuck coming loose. My Logan has a 2 1/4-8 thread, I recall, and takes 5C collets natively. It came with a three-phase motor which can be reversed "on the fly" though I changed it to single-phase.
