Looking for replacement brushes

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Joined: 12/01/2006
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Points: 706

All:

I'm looking to replace the ~four~ brushes in my ~1000 watt scoot hubmotor.

The brushes are 15CM long by 10 CM wide, and have a "tombstone" section, 5 CM thick one side and 5.5cm thick the other.

Anyone got a source? I don't mind filing down bigger brushes.

They've only lasted ~4K, but if I can get replacements, I don't mind. I know I've been loading it pretty heavily.

Mark

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Offline
Joined: 12/01/2006
Posts:
Points: 706
Re: Looking for replacement brushes

All:

As they say, YMMV. Well, my mileage certainly DID vary. In the event, I found brushes that could easily be cut down at a local vacuum repair business. The pigtails were much lighter, but it was a matter of 30 minutes to cut them to fit the holders.

What I DIDN'T do was reface the commutator. I didn't see an easy way to chuck up the entire wheel in my 9" lathe, and it didn't seem ~that~ badly eroded.

I also didn't do a long, low power run in to let the brushes at least wear in to get good contact with the comm.

I buttoned everything up, did a one-block test, and left it for my wife to ride to work.

In the event, she got about 1/2 mile before it sputtered to a stop with a strong burning smell. After I got it apart, all four brush holders had melted, and the carbon was heavily spalled. I assume that there was excessive arcing which overheated the brushes.

One dead hub motor. Sigh. Now I know why the motor shops always reface the comms...

The adventure continues.

Mark

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Joined: 06/18/2009
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Points: 7
Re: Looking for replacement brushes

it sounds like the brushes were not seated to the comm properly. small contact patch caused hi heat and melting of the holders.
refacing of the comm is done easily in the motor can by using an electric drill and hi-count fine emery paper.

i have heard of people using water on the comm to seat the brushes quickly.
sounds strange.. but they immerse the motor (comm anyways) in water and run it at a very low power level unloaded for 30-60 secs.
the water cuts the brushes quickly to seat them to the comm.
this is an old r/c car racing motor trick.

now the problem i see is sealed bearings don't like water immersion. you might not want to use this method if your not able to repack the bearings.

on the good side... the motor gets a good cleaning..

Offline
Joined: 12/01/2006
Posts:
Points: 706
Re: Looking for replacement brushes

Yeah. In hindsight, I'd seat the brushes. I think a few hours turning just fast enough to rotate would let the brushes seat. Of course, with an enclosed hub motor, it is a ROYAL pain to open it up enough to see how the seating process is going. That's part of why I just buttoned it up and hoped.

As it is, the brush holders are slag. I might be able to cast new brush holders in epoxy, but it will be a real project. In the meantime, the XB-600 I bought as a replacement is doing well. This scoot may go into the "lost pieces" pile...

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