Fan bearing removal, tips or tricks needed!

[dannycool]

Hi Guys

i have a AHU fan with a collapsed bearing that wont budge. All that is left of the bearing is the runner so there is not much to grip onto.
I have snapped a leg and bent the shaft on my pulley draw after having to virtually swing off it!
I was wondering i you guys have any tips on getting them off?
I have seen a trick with hot oil and liquid refrigerant but dont fancy that for obvious reasons!!
I am thinking as a last resort that i may have to go at it with a grinder and chisel but that is a ballache with the fire alarms and i dont want risk cutting into the shaft.

Thanks in advance

danny

[Brian_UK]

Are you sure that the bearing shell is meant to come out of the bearing support?

Try heating the support with a gentle blow torch.

Or have I read it wrong and you are trying to get the remains of the bearing off of the fan shaft?

Either way, same action, heat the bearing gently and then try it. If you have something like Pro-cool to keep the shaft cool then so much the better.

What can sometimes work is a good dosing with penetrating oil and then a sharp tap with a hammer or drift.

Good luck with it but beware of injury to hands from flying hammers or eyes from shattered bearing material.

[Quality]

Grinder is the way but use a slitting disc they are only 0.8mm thick and just go steady;)

[dannycool]

Thank for the response guys.

Brian, Basically the whole bearing has shattered and all that is left is the harderned steel grooved ring that the ball bearings sit in.
Anyway i thought about heating it up but surely being similar metals they will expand at the same rate??

Quality i am thinking that is the way forward, the only problem is getting the fire alarm isolated.
That is ironic really because it was the fire brigade who identyfied the fault in the first place! What happened was the bearing collapsed causing the fan the seize in it casing, which in turn caused the belts to slip and smoke the place out, the fire brigade was called and had to isolate the ahu. Quite a bizarre sequence.

[Gingerair]

Hi Danny

First clean along the shaft where the inner-race needs to slide off & the new bearing on, also clean up area where outer race is located.
If the access is good, weaken the old races by cutting into them as deep as you dare with a cutting disc, as quality said good thin one's are best. Try not to go so deep as to cut into shaft/carrier.

Now try to knock them off/out with a good hammer & drift, again trying to avoid damaging shaft/carrier, they may split were you've weakened them.

If they still won't move warm them to cherry red & try again with hammer & drift. Once up to temp another option is to get someone to pour water onto the shaft while you attack with the hammer, but you'll have to be quick..

The trick is removing the old bearing without causing damage so the new bearing can run true.

Make sure you wear goggles & gloves, the races will be hardened steel & laible to splinter if hit with a drift/chisel..

Good luck !!

[monkey spanners]

Tip a kettle of boiling water over it and whack it real quick!

[lowcool]

im with quality,two slits across the race should not be a problem even if you do score the shaft.used this process many times with 100% success

[Gingerair]

Forgot to mention before Dan, best to check that the parts you need for a repair are available. Know of parts go on smaller fan housings that arn't available as spare, only the complete housing & impeller. The bearing make & number should be on the side of the outer race. Also sometimes the outer race has a rubber bush insert that needs to be pressed in..

[dannycool]

Well Guys finally got it off with a grinder.
A neat cut along the line of the shaft with a cutting disk till there is fine slither of metal, then a swift whack with a lump hammer and cold chisel against the wall of the cut and the metal snapped!
No damage to the shaft, perfect!

Gingerair, we had to take the set off the rear of the fan to take to BSL and get a identical match. We are replacing both sets to be sure.

Thanks for the advice everyone

[Gingerair]

Well done Dan, always good to hear a success story !!

Sounds like you're a natural..Know of a bearing that needs changing on an old cooling tower if your interested or what about a motor side half coupling ?? They're normally fun & games :p

[LECKYBELL]

Hi Danny
Very thin cutting disc will cut like a knife through butter, you can also get very small discs to fit small die grinders which can be controlled very well.
Leckybell