In article ,
The Natural Philosopher wrote:
Without a gearbox you are talking massively high currents.


Not necessarily.

If you use extreme multipole designs, it is equivalent to gearing a 3
pole motor.You can step up the gear ratio by selecting different ways to
drive the poles.

Yes, that would work! Given enough brushes.

As long as the torque is sufficient to e.g. spin the wheels on a dry
road,thats all you need torque wise.

Which can be quite a significant torque.

We have a calculator for this:
http://www.4qd.co.uk/faq/current.html Motor Current Calculator

Indeed some cars do have motors in wheels, but performance on steep
hills if excessively poor. It really does not work for an electric
only car.

Furthermore, to maximise efficiency, the motor's brushes are offset.
This may mean the motor cannot be reversed (depending on the amount of
offset).


Brushes? gosh Richard, its rare to find you ten years behind the
times..

Given my age (64) I think I have adequate excuse!

Brushed P.M. motors still constitute the bulk of the small motor market,
so is where the bulk of controller sales is!

no one uses BRUSHES. In built optical or hall sensors for wheel
position and solid state commutation are the order of the day. and
variable timing. If you use permanent magnets for the rotors, you don't
even need slip rings.

I cannot disagree!

--
Richard Torrens -
The email address used here is time limited and must not be added to any mailing list: A charge will be invoiced for handling any unsolicited mailing list emails received.