Keyway Damaged

[Harold Brantley]

Mark, I have a badly damaged keyway on the shaft of a 13 hp Genrac. It is 7 yrs old but it doesn't use oil, smoke or leak. What are the options on fixing the keyway? I thought of having the damaged area welded, turned back round and a new keyway milled in the shaft. I assume the shaft has to be removed from the engine. How big of a job is it to remove the shaft? I'm not in a rush, I replaced the Genrac with a 13 hp Honda and then put on the EZ 3045 General pump I got from you several months ago.

 

[Paul B.]

I'm not Mark but:

It can be done but I would not weld on the shaft. If not done properly it can anneal or warp a shaft. I would cut a new keyway 180 from the old. They do make portable keyway cutters but I'm not sure if that shaft is large enough. May also need to be re-balanced if it was balanced originally (epoxy a plug in the old keyway would help with balancing.) If it was not balanced originally your new keyway will balance the shaft anyway.

Make sure the bearings are completely covered (if not removed) when machining - any dirt or chips getting into the bearing(s) will accelerate failure.

 

[Mark]

You could try installing a sheave / pulley on engine and going belt drive!

 

[Paul B.]

You still need a keyway for the pulley or the bushing to transfer your load. There is a device made by Ringfeder that works on friction but don't know/remember if it comes that small and transmit that kind of a load. Maybe a low profile unit for a pulley drive.

I don't know if they make a coupling type for direct drive applications. May want to call them at their 800 # and talk to an applications engineer. Try www.ringfeder.com or www.ringfeder-usa.com (I think they are of German origin but have facility in N.J.)
It's been over 5-7 years since I've used their products.

 

[Michael T]

Harold , I had the same problem a while back. I did what Mark said and converted to a pulley system. The sleave and pully system doesnt need a key way, It is held together by compression. If you are going from a direct drive to a pulley you will need a new pump. You have to be able to mount the pulley on something. Sometimes it is just time to buy new stuff. Take your depreciation and write off the new purchase. If you are like me you kind of hate to throw some thing out if it still works. Maybe it the influence from our previous generation! Thats a whole another subject. LOL Ive got a whole shop full of "Good" equipment . LOL Know what I mean.

Michael T / Centex Pressure Washing Service

 

[Paul B.]

Michael,

You're correct, ...they make keyless bushings.
(Guess I've been away from engineering too long ...the closest thing we had were the Ringfeders that could transmit high radial loads - Thanks for the schooling.)

Gates makes some and to quote them "some can be used over damaged keyways but must be carefully centered and others require a smooth shaft."

To me, the important thing is to purchase the correct part and install it properly otherwise you may damage the shaft if the bushing spins. Check with your power transmission supplier on specifics and power transfer for your particular application.

Regards,