On Sun, 19 Mar 2017 20:52:33 -0500
Martin Eastburn wrote:

The large motor likely has to much for slip.

If you mean a CONE pulley on both sides - likely.
Then why not an AC drive.

If slip - why not a AC drive.

No need for DC motor if not electronic speed control.
Those were in use at that time.

AC motors are lower cost than DC.

good points and questions
oliver may have drawings still of the mechanism

the motor maker is still doing business and looks to be high quality
stuff

blurb says motors up to 20,000hp
http://louisallis.com/

also the lathe was made in late 1940 according to the serial number