[morzh]

SO, was I right when I theorized that it was 2-ball regulator moving gears to change the gear ratio?
I cxannot quite tell it fom the photos, but sure looks like it.
Yes that is possible.

What is the rotor made of? Copper?

If it is, what yoou have is likely the induction disc motor. Very much the same type that is used in house electric meters (or used to be used).
It is based on rotating magnetic field and eddy currents in the disc.

A similar one:

https://www.ebay.ca/itm/134565999569
https://www.ebay.com/itm/364371922804

   


The same principle also exists in disc relays.
Basically the pole and the disc produce zero torque, but then you could divide the pole in half, and make a shorted turn around one half, thus making the torque non-zero.

https://www.nprcet.org/site/download?fil...otesu2.pdf

This is the article; find the "Induction disc relay" and "Pole shading method of producing torque"