Hi all,  Okay, this is my field as electrical engineer.

A step down transformer from 220V mains to 115V can be used for many
applications but, depending on the actual motor design, there can be
problems with heat.  This is because some motors are designed to run
very close to saturation of the magnetic core.

The reason for the motor failures mentioned earlier is overheating.
One assumes that, with a proper transformer, 115V should be delivered
to the motor and it should be fine; but the important factor is that
the 115V motor was designed to operate with 60 Hz AC whereas the
European mains deliverers 50 Hz.  In effect, this means that an AC
motor from USA will, first of all, run 50/60 times slower in Europe
than in the US and, secondly, it will run less efficiently because
it wasn't designed for a lower frequency, and hence the overheating.

The only way to overcome the speed problem is to use a larger pulley.
To overcome the heat problem, the only way is to reduce the voltage
to be 50/60 x 115V.  Hence, the transformer output voltage should not
be 115V but 96V.  This again comes at a cost of motor torque.

So, there is no ideal solution but I have had usable results with
running the motors on 96V from 220V 50 Hz mains [using a step-down
transformer].  I have also had large old motors that don't mind the
lower frequency and work fine on 115V 50 Hz.

Maybe this helpful to someone.

Kind regards,
Bernt Damm
Cape Town