radiator fan gearbox / shaft coupling problem

[coolbus]

 ?? I'm having some kind of problem with the radiator fan gearbox. Please help me to solve this problem!

A while ago I replaced the pillow block bearings on the shaft ahead of the gearbox. (you may recall my post "dreaded repair" -  it is so difficult to get to the bearings) The ball bearings were both shot - both failed at approximately the same time.

So I got new bearings (and pillow blocks) replaced them; fired up the bus, and within just a few minutes, the rubber insert (gear) in the Lovejoy coupling failed. Three of the 6 'lobes' broke off.

So I took it all back apart, put in a new rubber insert. Put it back together, fired up the bus, and just like before, failed again. The rubber gear lost 3 of the 6 lobes (every other one, just like before)

I'm not sure what is going on here; I have two possible suspicions: The new pillow blocks are possibly a little different than the originals. The shaft seems to sit a little less than an eighth inch higher than before. At least it looks about an eighth inch higher than the other side of the coupling. The mfg. (Lovejoy) states that the alignment can be out of tolerance without any problem. Is the (less than) eighth inch too much? I may be able to un-install the pillow blocks & shim them up.

The other possibility is going to be more of a pain. Could the gearbox have gone bad?  Seems like too much of a coincidence, but maybe that is what made the bearings go out too?

I checked the fan movement while it was apart last time - the gearbox feels perfectly fine. No wobble, no grinding, no apparent problems. I can take the fan blade & give it a spin by hand and it spins very freely while connected to the gearbox (with the coupling disconnected).

The gearbox seemed to be very low on 90wt. I added more.

How can I test the gearbox? Spinning it by hand may not be fast enough to indicate a problem.

I am about to replace the 2nd broken insert. This is not much fun working in that tight engine bay...

Thanks alot!

Mark

[Nick Badame Refrig/ACC]

Hi Mark,

Something is Not alligned.... I can't see the box locking up if all is free and no play.

I'm sure one of our members will know the fix.

Good Luck
Nick-

[Busted Knuckle]

Mark I know exactly what ya mean about working in a tight engine bay! And while I haven't had any personal experience with them I'd say the slight angle is not the problem! I'd be thinking that the bearings in the gearbox are "tight" (from insufficient lubrication) or worn out! But that's just a guess! If possible you might see if there is a way to spin it at a faster speed now that you've topped of the oil and see if it'll free up!
Again I don't know but I'd try it.
 BK  

[luvrbus]

coolbus,that coupling can be off a little aliment in one direction but not both,you need to take a dial indicator and make sure your shaft is not bent

[Barn Owl]

Coolbus,

I work with Lovejoy couplings everyday. You have an alignment problem. They are made to compensate for only a very small amount of misalignment. The closer you get the shafts to align, the longer the couplings will last. There are three alignments you need to measure:

1. Parallel shaft alignment
2. Angular shaft alignment
3. Axial shaft alignment

Start shimming my friend,

Laryn

[Dreamscape]

I agree with all that has been said. Alignment is the key, and very critical. I have installed many couplings in my line of work, yours just got beat up from misalignment. Check the alignment of both shafts, they can be off a little, a couple thousands of an inch, that's about it.

Good Luck and let us know what you did to correct it.

Paul

[coolbus]

I LOVE THIS BOARD!!!
Thanks for the suggestions. I will be on the repair tomorrow.

Will let you know how it goes...

Mark