Drive belt keeps jumping off beltwheel for my 2475 Ingersoll Rand

by David
(Stockholm, Sweden)

Hi Bill,
This just happened for the first time today. It took a long while to get into the belt housing cowl, release the tension from the motor mounts and get everything into place again. I tensioned everything up again - although I don't have a tension gauge - and it jumped off again, and so on 3 more times.
I've been thinking the motor and compressor wheels may not be aligned properly as the belt jumps the same direction every time, or there is something wrong with the belt, or the tension is wrong. I'm not sure what it could be as the unit is second hand and was built in the US about 2 years ago without much use until I bought it.
I live in Sweden and use the unit for air tools in an alloy wheel repair trailer.
Any thoughts or advice would be appreciated.
Regards,

David

P.S. Like the webpage - genius idea!

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Bill says...

David, glad you find the site useful. Thanks for the commendation.

If the sheaves are aligned properly, and the belt seems OK, what comes to mind is that the pump sheave may not be turning easily. The motor sheave keeps the belt moving at the normal speed, but the other sheave acts as a brake, maybe creates slack, and allows the belt to jump off.

Sheaves are not rocket science, and you can pretty much tell when a belt is fairly close to proper tension. What is it, a 1/2" play each way for tension?

It's clear that something has changed. Change the belt to a new one first. It's a low cost way to determine if it's the belt that's the problem.

Cheers,

Bill