# Belt Alignment



## Thurman (Feb 9, 2009)

A bit more info please: "Flip belt", are you saying the belt actually flips upside-down? I've seen this in mis-aligned drives. And: "One pulley (actually a sheave) is 1/2" and the other is 5/8". Are you talking about the shaft diameter or the width of the top of the "V" of the sheave? Have you pulled a string or used a straight-edge on the two sheaves to check alignment? Have you looked "one-eyed" at the belt down the length of the belt to see if it looks to be aligned? Too many variables here with too little info to diagnose, yet.


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## DexterII (Jul 14, 2010)

Air compressor belts need to be relatively tight, and the sheaves need to be in near perfect alignment, but the latter is sometimes hard to maintain while achieving the former. The easiest way is to use a set of adjustable motor rails, but they take up space, and can be cost prohibitive on smaller units. One alternative, although requiring a bit of trial and error, is to tighten both the pump and motor in place, using a framing square or straight piece of angle iron as an alignment guide, and then roll the belt in place. I don't know if this helps, because, as Thurman said, some more information would be quite helpful. And, at first glance, not knowing any more about it, I tend to disagree with your belt shop; there are various size belts, which require various size sheaves, and vice versa, and although some things don't care too much, something that starts as hard as an air compressor is not as forgiving.


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## jburd964 (May 4, 2009)

The width would be the of the sheave and the belt actually gets on its side not completely flipped but close enough. I've actually put straight metal yard stick and a square on pulleys as well as checked the square of both compressor and motor with the mounting platform. The results are always the same, flipped belt. The belt itself seems to have a slight twist it but every slight, I think its from being flipped. Tomorrow I'm going to actually get out the caliper and get it on the money. If that doesn't work I guess its a new belt then matching the pulleys.


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## forresth (Feb 19, 2010)

try a new belt. belts can do very weird things if they've been run at all the wrong way or misaligned.

If you put a snowmobile on backwards after it had been run forwards, its a ticking time-bomb. I did it once and made it 5 miles of easy riding before blowing up. they normally lasts thousands of miles.

I have a double belt on a small sawmill that was run crooked for awhile, and was all over the place after I got it straightened out. It took about an hour of use to "calm down". If it was a pair of singles, it wouldn't have been an option.


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## jburd964 (May 4, 2009)

I took my time today and used a straight edge and found the motor twisted out of line by 1/16" across a 4" pulley. I had to rig up hooked bolts to pull the motor straight and tighten belt at the same time. I seem to have worked. What a pain, don't think I've even had anything so finaky with belt alinement.

I'm not a professional., But I did stay at Holiday Inn Express last night.


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## Thurman (Feb 9, 2009)

"belts can do weird things", is so true. Especially if the belt has been run ANY at all out of it's proper position. The cords within a "V-belt" can/will stretch one-at-the-time and this will cause a belt to run all over the place. Now that you have found an alignment problem and have it corrected, please go buy yourself a new belt to put on this compressor. Maybe the old belt is running now, but as stated: It is a ticking time bomb before it shreds apart or completely flips over. I've even had to work on machinery with eight (8) "G" belts where the middle two had flipped over. Replace them all while in there, just to be sure.


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## jburd964 (May 4, 2009)

Ran it longer today and it filled again. That was a new Kevlar belt that the tool shop had put no it. [email protected]#*!#^^


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