How can I straighten a large cast pulley?

bpimm

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My compressor just flipped another belt, the pulley on the compressor head has about .5" of wobble and I think that's what's causing the belt to give up, only happens every couple years but I thought it was time to see if I can fix it.

There is no ID tag on the compressor head but the name plate on the mounting plate says Kellog Model EM33-E. The shaft is strait, I put an indicator on it and turned it over by hand so the wobble is in the pulley. My original thought was to bore out the center and bush it back down to the shaft size but my lathe isn't big enough to grab it by the outside. the pulley outside diameter is 22.5". After getting the pulley off the compressor I'm not sure if I can do the bore and bush because the hub has a thin extension on it that might be compromised by the bore.

Any suggestions for straitening this thing out? I have a HF 12 ton press and a porta power to work with.
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Yours is in better shape than mine, It also has a wobble and has for as long as I can remember, it is the same one that my dad had on his truck for fixing large tractor flats. don't remember it ever throwing a belt. Mine was built about 1966
 
What sort of belt does that take? It doesn't look like a normal v-belt. Ordinarily, I would just suggest buying a new pulley, but I'm not sure where I look for one of those. Maybe SI-SDP?

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Obviously you need a bigger lathe to do this job:grin:

Seriously though, if you can't resolve the issue with adjustment I would be reluctant to do anything. A part like that is under more strain than I would like to mess with, at the very least consult someone with real experience in the field before attempting anything.

JMHO....

John
 
I think it is just a standard 5/8" v belt, just 4 of them. I've only been running 1.

Kvt the only date I can find is on the tank and it's 1936
 
If you put pressure on that pully to correct the wobble it will BREAK! I would mount it on a known true shaft to verify the crank is not bent, I have seen mang bent crankshafts. If it wobbles & the crankshaft is true then it's a machining problem & was that way from the get-go. How many belts do you run on it? There is paint in the belt grooves. Have you used a POLY BELT? Checked belt alignment?

Just saw you only run one belt, I would almost bet if you used 4 MATCHED belts or POLY-BELT problem would be solved. Just my 2 cents.
 
They built it that way for a reason, try more belts.

It's unlikely the spec requires it to run very true, as long as it's driving the pump it's doing the job it was designed for.

John
 
When you say "wobble" do you mean axial or radial? Simple English is is moving side to side in line with the motor or is it moving in the direction of the belt travel?

The first could be a casting flaw that can't be corrected or it could be a misaligned bore which could be fixed. The second would be an off center bore which could be fixed.

My guess for why you are running it with one belt is that the pulley on the motor you have only has one track. It would actually be easier to make a replacement for that with 4 tracks and run it with 4 belts.
 
Does the wheel appear to be damaged? How old is this machine? Perhaps it has been like that since day #1. Granted it would be nice if your drive belt didn't jump off from time to time - but I'd have a go at playing with the alignment, play with the tension, try a couple different types of belts. I agree it would be nice if the flywheel ran mostly true - but don't wreck it trying to fix what isn't really broken.

I have a 5HP compressor with a flywheel about that big - it has two grooves but it only had one belt on it when I bought it 18 years ago - it was far from new then (I'm still running the same belt it came with).
 
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