Wouldn't it be better to have coils going in two directions?
closed as not a real question by Dave Tweed, Olin Lathrop, embedded.kyle, Kaz, W5VO♦ Dec 8 '12 at 8:09
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If you are speaking about a regular brushed DC motor, it's just the way the inductors work:
The windings produce a magnetic field (which will interact with the permanent magnets to produce motion), and the direction of the magnetic field is related to the direction (clockwise or counterclockwise) you make the windings.
So if you wind it in both directions, one generated field is going to cancel the other. It's hard to make it short, since it involves too many concepts, so I recommend you to search for inductors, DC motors and magnets.