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Join Date: Apr 2013
Posts: 1

Welding Electric Hoist Shaft

04/15/2013 9:00 AM

Is it permissable to weld a shaft on an electric motor that is used in a hoisting operation?

In particular this motor shaft is directly connected to the gear reducer via coupling that raises and lowers the hook from the crane.

The shaft bearing fit needs brought back to tolerance and the keyways at the end of the shaft are "stretched" and would require weld, then machining and finally milling for a new keyway.

Is there a spec that states "no welding is permitted on a lifting device"?

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#1

Re: Welding Electric Hoist Shaft

04/15/2013 9:06 AM

Why not just replace it with the strategic spare held in the stores, and re-order the spare from the supplier?

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#2

Re: Welding Electric Hoist Shaft

04/15/2013 10:16 AM

Hi William,

I doubt there is a spec. that states "no welding is permitted on a lifting device" but alarm bells are ringing loud.

How big and old is this crane and what industry is it in?.

With the amount of "damage" you quote it sounds as if it has had a hard life.

Does it under go an annual service and certification by a specialist company for insurance purposes?

I would think it would need a thorough going over before it could be used again.

Best of luck in your endeavors, cross all the "t's" and dot all the "i's" mate.

John

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#3

Re: Welding Electric Hoist Shaft

04/15/2013 10:40 AM

Not knowing where you are and what the service requirements of the crane are, I'd say, NO!

Relace the shaft with the proper replacement part.

No useable information here to work with.

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#4

Re: Welding Electric Hoist Shaft

04/15/2013 11:26 AM

Welding on the shaft will change the temper of the metal. Which may cause the shaft to fail. Repairs of this type are usually only done on large motors where it is cost effective. As the shaft after the key way was filled in is then spray welded oversized then tempered and reground to size.

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#5

Re: Welding Electric Hoist Shaft

04/15/2013 12:21 PM

If the person or people doing the welding and machining know what they are working with then there should be no problem. Most electric motor shafts are made of medium carbon steels and take welding and remachined well.

I have done it a number of time to fix old motors or to change a shaft to a different size or length or fix a keyway and have never had a failure yet.

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#6

Re: Welding Electric Hoist Shaft

04/15/2013 12:42 PM

I think this would come under the definition of 'modification' of the equipment by an unauthorized party, which would be forbidden by any elevator, etc. codes I have encountered. I think this situation illustrates why codes have such a clause - can you imagine how many "Thou shalt not . . ."'s would have to be in a code to cover all bad ideas. Fix it right Have it repaired correctly.

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#7

Re: Welding Electric Hoist Shaft

04/15/2013 10:10 PM

Some codes distinguish between lifting of people or lifting above people, versus lifting where people are not at risk. Please consult your local regulations.

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#8

Re: Welding Electric Hoist Shaft

04/20/2013 10:23 AM

Seems like there's more work required to fix it than just replace the motor shaft. Consider the risks of screwing up the repair. Not worth the gamble in my opinion. Just order the replacement shaft and be done with it.

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