On 9 Mai, 22:29, Christopher A. Lee wrote:

I don't know about the Italian system but the American one had single
speed locomotives because the AC motors were synchronous.


The Italians used squirrel cage motors which don't strictly require
synchronous running.

Different speed settings could be obtained by the switching of poles.

Resistors were used for the internediate speeds.

So not too different to a DC setup really.