ID'ing AC motor.

[omgwtfbyobbq]

I picked up a small air compressor off of ebay on the cheap. The owner said it wasn't going above ~50psi, so I open it up and check it out. It has two AC motors connected to two oilless pistons and it turns out one of the motors has burnt out. When I pulled the burnt motor out of the case, it was missing those little *square things that are in line around where the wiring leads to, if that makes any sense. Anyway, I was hoping to figure out what kind of motor it was, but it has no serial/ID number anyplace. Based off of the physical dimensions of the motor is there any way I could track it down and purchase it? I'd rather not go through the manufacturer since they'll probably gouge me.

*I can post up picks if anyone needs them.

 

[Dean Huster]

More information (manufacturer, model) and the pic of the "square things that are in line" would be helpful. Since it's a compressor on the cheap, it's likely that you have universal motors and the square things are brush holders. In all likelihood, you're going to have to bite the bullet and order replacements through the manufacturer. Look at it this way: you saved lots of money buying it in the first place, so you have some wiggle room to spend the money on decent repairs. Assuming the two motors are identical, at least you know what you're looking for.

Dean

 

[HiTech]

can't tell for sure what you mean regarding those square things in line but perhaps they are brushes? Do they contact one end of the motor's armature (the large part that rotates that's either outfitted with coils or serrated magnets. Brushes can be replaced if those are it but you need to get exact replacements as well as clean the contact zone that they rub against. Do not use abrasive materials to clean. As for oiless compressors, often they are a finite life product. They don't last long, generate way too much heat, and fail rather easily over the compressors that have an oil sump and employ a series of piston rings to provide compression and oil sealing.

 

[omgwtfbyobbq]

Here's a picture. The little tiles(?) on the small end of the rotating assembly either flew off or melted? Could this be fixable?

 

[JimB]

The "little tiles" are known as the commutator.

If they are worn or grooved, someone who has a lathe could "skim" it for you.

If they are burnt, melted or missing, you need a new motor.

JimB

 

[HiTech]

LOL... it's an oiless compressor ... forget the motor, he needs a new compressor ... or that is, he will need one soon!

 

[Roff]

Here's a picture. The little tiles(?) on the small end of the rotating assembly either flew off or melted? Could this be fixable?

[sarcasm]Couldn't you make the picture any smaller?[/sarcasm]
Sorry. We could tell a lot more if you posted a bigger picture.

 

[omgwtfbyobbq]

Yep, it's the commutator, half of it/them is/are gone? I tried calling up the manufacturer and they only replace both motors at once for $60+tax&SH! Talk about a rip... Not that "oilless" compressors are any less reliable than oiled compressors, they're just designed to be chucked as a unit as opposed to regreased (little rubber piston rings), probably more profitable that way.
Thanks for all the help!

 

[JimB]

$60, for two motors and someones time for removing the old motors, installing the new ones and testing.

+tax, even GWB has to eat, not to mention that big white house he lives in and the fancy aeroplane he rides around in.

+SH, the post man has to eat too you know.

So, how much did you pay for this bargain compressor (known to be a bit iffy), and how much is a new one?

JimB

 

[HiTech]

Talk about a rip... Not that "oilless" compressors are any less reliable than oiled compressors, ...

That's just it, man! They are generally less reliable than oil-sump compressors for that and a myriad of other reasons. About the only benefit they offer is no oil blow-by past the rings for spray painting. But there are countless compressors in use everywhere that use oil sumps along with air dryers and filters to provide clean, dry air. Go buy yourself a small "pancake" or twin tank type compressor that has an oil sump and it should provide years of reliable service.

These two types require oil:
**broken link removed** **broken link removed**


This type of compressor pictured below are typically oiless:
**broken link removed**

 

[omgwtfbyobbq]

This one was ~$15 all told (Cost plus gas to pick up), came with all the hoses and fittings etc... A new one seems to go for ~$50-100 shipped, not sure about fittings. The thing is, I bought it figuring I could use it for parts even if it had some problem that wasn't worth fixing. For instance, I was thinking about using the tank and pressure switch with another compressor if/when I saw one on ebay for cheap, take the remaining AC motor/piston and use it in a biodiesel processor, or stick on the shelf for future uses. Or, I can seal off the other piston (it wouldn't go past 40psi because the vibration and high pressure would let air out of the inactive piston) and use it for what it was originally designed for, filling up tires, slowly . I figure the tank/accesories are worth ~$15 alone. This is also so I could get an idea about how various types of compressors work, which is why I said oilless aren't any less reliable, just designed differently... instead of changing the oil every so often, they need to be regreased every so often. In the case of this compressor, one side must've been near a dust source because the grease in the piston associated with the motor that burnt out was dark, very dark (way more physical resistance). In any event, it was more to take apart and possibly use then to rely on. I've got my eye on a nice looking 220v 80 gallon compressor on ebay, but since I'm not going to paint my car any time soon, I'll probably pass and get one later. I've got plenty of other projects that need attention.