Well it all depends on what sort of motor it is. All use magnetism in the
end and how the poles that repel and attract are arranged makes many shapes
possible. Some direct drive motors operate via locally generated dc or
different frequency ac.
Thos generally are used when speed differences are required, unless the
device has more than on motor, or has switch windings to make it change
speed and torque.
Brian

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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"DerbyBorn" wrote in message
2.236...
Most motors seem to have the same proportions of length to diameter so
there must be some theoretical principal there.
However, I once operated a milling machine that had what was called a
Pancake motor that drove the feeds. It was large diameter and only about 2
inches deep. Then there is the direct drive washing machine.

Any website I should read to clear this in my mind.