Air compressor woes

[Charlie Chops 1940]

I have a Type 21 2-stage Ingersoll-Rand 5 hp upright compressor about 15 years old. For a few years now it has started hard. Last week it refused to run...wanted to start but kept tripping the breaker. Took the motor for service. They cleaned, tested, replaced the brushes, relieved me of $85 and said it was good to go. It started once slowly and filled the tank. The basic problem remains. The check valve to prevent backflow from the receiver (tank) to the compressor seems to be okay...seats good, no rust. I can turn the compressor by hand easily.

I've tried to find trouble shooting that seems germain on the web but no luck.
Likewise I can't seem to locate any info on the Ingersoll-Rand sites.

Do any of you guys have any expertise in this equipment?

Thanks in advance.

Charlie

[34ford]

I assume that it's runs on 220 volts? If so are both fuses or breakers in the box good or could it just be running on 110 volts. Just a thought.

bob

[Charlie Chops 1940]

I assume that it's runs on 220 volts? If so are both fuses or breakers in the box good or could it just be running on 110 volts. Just a thought.

bob

No, it's not running on 110.

Charlie

[tom36]

Just a shot in the dark, but is the unloader working?  Thats that square box with the small tubing going back to  the compressor head.  It's purpose is to relieve  or "unload" the compressor head so it will start not under load.  Also, perhaps the breakers are weak?  tom...

[58 Yeoman]

Capacitor start?  Weak capacitor?

[Charlie Chops 1940]

Just a shot in the dark, but is the unloader working?  Thats that square box with the small tubing going back to  the compressor head.  It's purpose is to relieve  or "unload" the compressor head so it will start not under load.  Also, perhaps the breakers are weak?  tom...

I'll take a look at that Tom. I heard it hiss last time the machine shut off but it might not be fully functional.

Charlie

[GPster]

You mentioned brushes. If that's what you ment I think it's referred to as an Induction motor. I've never worked on them but I watched with interest while somebody did years (30) ago and the placement of the brushes has a lot to do with the starting power and can even change the direction that the motor runs. The old time motors had the brush holder fastened to the end bell with screws in slots so that the timing of the brushes could be tuned. If your motor is anything like this the brush holder may been put out of time when he changed the brushes. Bench starting a motor with no load might not have revealed that problem. Also some times the radius edge of the brushes may be reversed so that they are not in correct contact with the commutator on the armature. Funny you should have this problem now (not really). Yesterday I got a set of spark plugs in that V6 I've been learning on. The starter that I've been using was the one in the flood. I took it apart and cleaned it up and it seemed to roll the motor just fine with lubrication in the cylinders and no plugs. With plugs in it wouldn't roll it fast enough to start and the starter got "smoking" warm. Pulled it apart again to find the brushes so warm that the bakelite brush holders were rubbing on the commutator and not allowing the brushes to make firm contact. New brushes today will tell me if I'm right or just relaying useless information. GPster P.S. What is a cleaner that I could use around the windings of this starter that won't attack the coating on the windings?