# Converting a PMDC motor: 2-pole to 4-pole. Possible?



## major (Apr 4, 2008)

Amberwolf said:


> is it possible to cut the armature wires at the commutator segment joins, and rewire between them so the fields will be correct to work as a 4-pole motor?


Hi wolf,

In short, no.

2 pole armature has the coil sides (wires in the steel slots) spaced approx 180 degrees. A 4 pole armature needs coils side spaces at approx 90 degrees. So a complete wire tear out and rewind is required. And then there are the magnets. You'd need to change to N-S-N-S instead of the N-S 2 pole arrangement.

I don't understand why you think you would need to do such a thing. The only gain would be double brush area.

Regards,

major


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## Amberwolf (May 29, 2009)

Thanks; I was fairly sure it was going to be more complicated than that. 


As for the reason, during my research on motors being used for EVs and ebikes, whenever 4 pole vs 2 pole motors are discussed, it seems to be implied the 4 pole type has more torque than the 2 pole type. 

I do know that with my pancake style radiator fan motors, which had 4 brushes (assuming they were 4 pole?), they had significantly more torque than I expected to get out of them, since two of them were able to friction-drive my bike, using 36V instead of 12V, even though they were core-less armatures (no iron). Other radiator fan motors I'd tried with only 2 brushes could not do this. 

So I assumed (perhaps incorrectly) that motors with 4 poles (or at least, 4 brushes) would produce more torque, probably at the cost of less speed and higher current draw.


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## Georgia Tech (Dec 5, 2008)

Hey if your intresrted I have a 4 pole 12 volt 3/4 hp 1800 rpm motor, continous duty too..let it go cheap too


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## Amberwolf (May 29, 2009)

I'd love to take you up on it, but I literally don't always even have enough money for rent/bills on time, due to too few hours available to work. 

It's one of the reasons I build everything out of junk other people don't want--even if it doesn't work, or work right, it is free, and all I have to do is deal with it's "quirks" and design around them. 

If I'm lucky, I'll find a better job eventualy, but it's been two years of looking since CompUSA shutdown here, and no one else wants me so far, cuz I'm older (41) and experienced. If I do, and you still have it, depending on price I'd take you up on that.

The motors I have now do work to help me along; I'm just always trying to improve things.


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