What's new

How the F do I know what brushes my ancient compressor motor takes?

DMG

Red Skull Member
Joined
May 20, 2020
Member Number
495
Messages
2,230
So the Wagner 220v motor on my shop compressor started running slow and sparking around the brushes. I shut it down ASAP. I am guessing it needs brushes. How do I look up the brushes for it?
 
Post pictures. Do you have a electric motor shop or bering supply near you?
 
.....

20201006_174859.jpg
 
make sure they aren't hung up first, sometimes they get stuck in the holders and that'll fuck your commutator up fast if you don't catch it right away
 
Around here the local hardware store (Ace but supplied by don't best hardware) has a large selection on hand.

As mentioned you'll have to pull them and take them to a store or measure and dig them up through a supply house.
 
We have a 5 gallon bucket full of random brushes left behind by the elevator repairman. So far I've always been able to make something work from there with a little bit of filing. But defiantly check that they are moving free and the springs still have tension.
 
My grandfather used to repair electric motors and grainger can still support a lot of obsolete old stuff. If you can’t find what you need anywhere else Grainger can probably get it.

I forget where you live but there’s probably an 80+ year old man somewhere around you with the tools to dress the armature before you stick new brushes on it. I can’t remember what it’s called but there is a tool that looks like an eraser made out of what looks like ceramic for dressing the armature where the brushes rode on it the last 50 years.

edit: commutator dressing stone. Amazon has them for $12 bucks
 
My grandfather used to repair electric motors and grainger can still support a lot of obsolete old stuff. If you can’t find what you need anywhere else Grainger can probably get it.

I forget where you live but there’s probably an 80+ year old man somewhere around you with the tools to dress the armature before you stick new brushes on it. I can’t remember what it’s called but there is a tool that looks like an eraser made out of what looks like ceramic for dressing the armature where the brushes rode on it the last 50 years.

edit: commutator dressing stone. Amazon has them for $12 bucks

Thanks, I’ll be ordering the stone.
 
20201007_085809.jpg
I can't believe it has brushes, strange. It isn't starting contacts you're seeing sparking is it?

I may be having a language problem here.
 
Last edited:
Lol.
Take apart, measure, buy closest (make sure to check how the wire is attached, were it goes, how it's oriented), grind, solder, clean commutator, polish a bit unless it's fubared then stick it in a lathe and try something, install.
 
Last edited:
Those are definitely brushes, I learned something today!!!11one.

1750rpm AC motor meant induction motor to me. I'm really curious why it was done that way, should be able to run on DC. Does the RPM change with compressor pressure?
 
Those are definitely brushes, I learned something today!!!11one.

1750rpm AC motor meant induction motor to me. I'm really curious why it was done that way, should be able to run on DC. Does the RPM change with compressor pressure?

Nope. This is a heavy as fuck probably 50 year old compressor that came with my old shop. The old guys didn’t want to move it so they gave it to me. It is loud and has no features to improve safety, efficiency, noise output, etc. I can’t imagine enough DC to spin this thing. But as you can tell by this thread, I am far from an expert.
 
Today I took it apart and found an electric motor repair shop (Walters electric repair in Latrobe) where we matched up my brushes with some new ones. It is back together, running great and ready to squeeze air for another 50 years.
 
Post pics of the brush out of the holder and use a caliper and measure them ~ I'll ask my ex boss he knows everything about AC & DC motors.
 
  • Like
Reactions: DMG
Nice, it probably will last another 50. Are the bearings oil-able? Or greaseable? Not much to go wrong with it.

I’ve got a 20 hp 3 phase motor at work that wiped itself out. Not that old but has greaseable bearings that I think someone pumped grease in that didn’t mix with the previous grease. It’s ran by a VFD and the VFD faults for overload when I try to turn it on.
 
Nice, it probably will last another 50. Are the bearings oil-able? Or greaseable? Not much to go wrong with it.

I’ve got a 20 hp 3 phase motor at work that wiped itself out. Not that old but has greaseable bearings that I think someone pumped grease in that didn’t mix with the previous grease. It’s ran by a VFD and the VFD faults for overload when I try to turn it on.

According to motor people (like Siemens), electric motor grease is very, very specific grease, and if combined with other greases it will either turn to oil, or (more likely) harden and solidify. I have been told multiple times how important it is to use only the correct stuff, in the correct amount, at the correct hours.

Also, less or no grease is better than too much grease. I believe this part because we've got motors (150 hp) that almost never shut off, and have lasted 10+years. Lots of them.

I have no idea why, and it seems stupid to need such special stuff.
 
Last edited:
Nice, it probably will last another 50. Are the bearings oil-able? Or greaseable? Not much to go wrong with it.

I’ve got a 20 hp 3 phase motor at work that wiped itself out. Not that old but has greaseable bearings that I think someone pumped grease in that didn’t mix with the previous grease. It’s ran by a VFD and the VFD faults for overload when I try to turn it on.

They are oil-able. I removed the little plug and squirted in a few drops of Mobil 1 after I reassembled it. I am going to change the oil in the compressor side this week, too.
 
Post pics of the brush out of the holder and use a caliper and measure them ~ I'll ask my ex boss he knows everything about AC & DC motors.

Thank you for the offer but it is fixed.
 
Also, less or no grease is better than too much grease.

after needing to take apart the fucking parts washer motor to scrape out pounds of fucking grease the second time I took the fucking zerks off of it
It isn't idiot proof, but at least it has made it slightly more idiot resistant
 
According to motor people (like Siemens), electric motor grease is very, very specific grease, and if combined with other greases it will either turn to oil, or (more likely) harden and solidify. I have been told multiple times how important it is to use only the correct stuff, in the correct amount, at the correct hours.

Also, less or no grease is better than too much grease. I believe this part because we've got motors (150 hp) that almost never shut off, and have lasted 10+years. Lots of them.

I have no idea why, and it seems stupid to need such special stuff.

It's a real deal though. We have thousands of pumping units at work, (pump-jacks) and they take lots of grease for the big bearings. I have about 30 of them and the only one that has grease-able bearings is shot, either to much grease or looks to me like incompatible grease burned it up. The bearing on the output shaft end went out and the belt tension pulled the armature into the magnets on one side. They only get looked at once a week unless they stop running so it sat there and chewed itself up till it seized. I'm going to replace it with another sealed one and it'll outlast my time here.
 
They are oil-able. I removed the little plug and squirted in a few drops of Mobil 1 after I reassembled it. I am going to change the oil in the compressor side this week, too.

That should do it, any light viscosity oil should be fine. Did you dress that commutator or just put it back to work? Might be the picture but it looks like it was in pretty ugly shape which happens when the brushes reach the end of their life. The sparking you saw burns the outside but a few turns with even some emery cloth can make them look new again.
 
That should do it, any light viscosity oil should be fine. Did you dress that commutator or just put it back to work? Might be the picture but it looks like it was in pretty ugly shape which happens when the brushes reach the end of their life. The sparking you saw burns the outside but a few turns with even some emery cloth can make them look new again.

I spun it by hand with fine emery cloth.
 
Top Back Refresh