three pole electric motors

[Al Skierkiewicz]

Originally posted by Solace
does anybody know how to set up the brushes on a three pole electric motor? I know how to do it on a 2 pole motor, but i can't figure out how its done on a three - pole one. please, this has been bothering me all week.

Jake,
I am not sure what you are asking here. The brushes for a three pole motor are the same as for a two pole motor. i.e.180 degrees apart. The commutator is something else again. In simple motors there are three contacts on the commutator roughly 120 degrees apart, with each winding wired to two of the three. If one brush is in contact with the center of a commutator segment, then the other brush in contact with both of the remaining segments. This puts one winding into a north/south the second winding into a south/north and the third winding is shorted out. Both energized windings then attract their opposite magnetic poles and spin the motor. When the brushes contact only two segments, then two of the coils are in series (half the current but twice the magnetic field of one coil alone) and the third winding is in parallel with the first two but opposite polarity. Does that answer your question?