Removing a stuck bearing

[SparWeb]

This should have been easy.



I'm replacing the bearings on my genny.  The rotor's rear bearing came off without complaint but the front bearing got stuck half way off, pulling harder just broke the outer race.  Now I can't get the puller to catch on the remains of the inner race.



There are lots of magnets on the rotor, glued and screwed down.  It's hard enough to manage that I don't want to take it to just any machine shop for the guy to push through his machine press - it's likely to jump out of his hand and crash into the press frame because he won't be careful enough with it.

Heat it or cut it???

[Harold in CR]

 Angle grinder and thin cutting disc ? Make 2-3 cuts, so the hard race could crack when struck with 2 hammers, like cracking a nut.

 Just the heat from 2-3 cuts might also swell the race enough to tap it off.

[Old F]

My self I would cut it all most to the shaft with a 1/16 grinder blade. Then wedge a cold chisel in to the cut crack the last bit.

Hot tip when you get it off and cleaned up use never- seize on the shaft.  So the next time the bearing will come off with out breaking.

[Frank S]

more than likely the race has stuck only because of oxidation build up like mentioned cut and split the race  use 2 cuts though to make things easier
 be sure to emery the shaft clean before installing new bearing

[dbcollen]

heat one spot on the race with an acetylene torch till yellow hot and the race will come off easy

[dnix71]

Done this lots of times. Use a dremel like rotary tool with cut off disks. One cut and a cold chisel into the cut will crack it loose. An old flat tip screwdriver hammered into the cut slot will do the same. Add some oil once it's cracked loose and work it off, then be sure to sand the rust off the shaft.

[fabricator]

Yep, a cut on each side with a cutting wheel on a die grinder, then whack it, don't heat it you want it to stay hard so it'll shatter. QED.
I'm surprised you didn't polish that shaft before you tried to pull it.

[SparWeb]

OK that worked.  I made 2 cuts with the dremel , using the 1/16" cutter disk.  Cut as deep as I dared, and whacked it with the cold chisel.  No effect the first try, so I cut a little bit deeper, then hit it again and it cracked.  I nicked the shaft with the dremel, ever so slightly.  But at least the bearing is off.

Fabricator, you're right, I could have prepared a lot more before starting.  Serves me right!  Would have spent 15 minutes with sandpaper, scotchbrite, and a check with a micrometer, rather than 4 hours cranking, cursing and almost breaking the rotor.

By the way, while trying to look for ideas on other websites like "practical machinist" I found lots of advice that made no sense, like running a weld bead around the inner race. For the record, that sounds like a bad idea to me.  They seemed to think that the post-weld contraction would made the bearing race bigger...     The other advice about heating it up with an oxyacetylene torch sounds like inviting disaster, warping the shaft.  Then the craziest folks say they put the cutting torch on and remove the race with that!!   

You guys are the best.  Thanks!

[Old F]

Spar another hot tip, a can of good penetrating oil like PB blaster can take out a lot of the cussing fussing when trying to unstick things

[SparWeb]

Oh yeah I buy WD40 by the 6-pack.  It was liberally applied while pulling, to some effect.  Just not enough, that's all.
I'm definitely going to pick up some Never-seize as you suggested before.
Thanks again.

[Frank S]

Sparweb  you can find any number of suggestions on the web especially in the practical machinist
 Had this been the outer race you could have run a weld bead around the inside when it cooled it would have contracted I used to rebuild a lot of heavy equipment some had bearings as large as 10 feet in diameter. on some we would even use an entire 300 gallon bottle of liquid nitrogen to freeze the race lots of fun on a bearing that weighs over 2 tons
 on oilfield mud pumps to remove the liners of the fluid end a few dozen very hot passes inside the liners and out they would come or the valve seats as well.
 There is a procedure to remove or repair just about everything.
 welding the outside of an inner race like you had would be tricky as you would need to be ready to remove it quickly or if you could have turned the rotor on end and welded around the race with a very hot pass gravity may have allowed it to slip free without very much heat transfer to the shaft but as I said it can be tricky.

[hiker]

heat the race good and hot--then stick the shaft end in ice..the rapid cooling  and contraction of the shaft should make it easyer to break the race free............

[Flux]

The slitting wheel method works a treat. For the outer race welding round the track works great but normally ball race are not a tight fit on the outer housing.

Once steel on steel has cold welded there is little chance of getting enough heat intio the inner race to expand it quickly enough that the heat doesn't transfer to the shaft. Dustin's method of heating one point to red heat with an oxy acetylene cutter usually works and if it doesn't you can blow it through with the oxy  without damaging the shaft if you are careful.

I have not tried a ring of weld on an inner race as the slitting wheel does it so much easier, I suspect frank is right, you have little time and without a puller on it ,it might lock on even tighter.

The other issue may be arc blow trying to weld on a shaft with strong magnets, I once tried to weld a loudspeaker magnet assembly ( interesting challenge).

Flux

[ruddycrazy]

Back in the days when I used to repair gearbox's I found the easiest way to get bearing off shafts was to just stick the shaft on the over head crane so i could spin the shaft then apply the oxy torch to the bearing while slowly spinning the shaft. Worked a treat every time and saved a heap of work using a puller. Now when installing bearings using an induction heater I used to heat most bearings to 110C and larger bearing over 8" to 95C. Then the bearing would just fall on the shaft easily and with some weight on the bearing would stop it raising that few thou. As said above on must make sure the bearing journal is clean and burr free before ANY bearing installation/removal.

Regards Bryan

[SparWeb]

Now that you point out that the weld bead works when put in the OUTER race, now I see what they meant (on the other website).  In future cases where I have one stuck in the housing, I could try that.  A little dicey with my MIG, but I know a guy with a TIG that's much more delicate.

By the way, before I started grinding the race, I wrapped the mags with plastic to keep the grinding dust off, and then wrapped that with rags as an extra layer to catch the dust that did drift that way.  Unwrapping the rags carried the settled dust away, and the plastic kept off any remaining dust still suspended in the air.  So no contamination so far.  Just a bit of the white spray paint flaked off (the original coating on the magnets is still intact and the paint doesn't stick to it well).

[phil b]

I sand the shaft lightly, apply some axle grease and try a bearing race puller.  http://www.harborfreight.com/bearing-separator-and-puller-set-93980.html
If the race doesn't budge, tighten the puller, then heat it with a torch while staying off the shaft as much as possible. When the race breaks free, it usually pops. When the race reaches the grease, it will be easy to crank it off. I've used this method on 1/4" to 6" diameter shafts.

[XeonPony]

me I use a socket or a pipe and beat it down clean polish shaft then off you go. Doing hot tub pump maintenance that is what you do 99% of the time, usually when the front impeller goes so does the frond bearing. You think you've seen corrosion befor!?!?!

[camillitech]

Another alternative on smaller bearings is to grind a flat and twist off with a spanner,



may help if you can't get near a vice or anything solid



These stator bearings on the old Rutland wind turbines are always seized 

Cheers, Paul

[equiluxe]

I usually grind a flat or two until there is less than a mm of metal left then use a cold chisel at a tangent as if driving a stubborn nut the race then just pops in half and falls off. It is a good idea though to have a few proper bearing/gear pullers of the type that split in two and are held behind the bearing with two bolts these go right up to the shaft if you use a pulley puller they just put pressure on the outer race and will often render a bearing useless when removing it from distortion and as you found out they can pull the bearing apart. Sorry about the advertizing it was the only photo of the type of puller that I was referring  to that I could find quickly.

[SparWeb]

Thanks.  I have a similar tool.  That central threaded rod is the limiting factor.  When I had mine on, and cranked, I was at the limit of my ability to turn a 11/16" wrench, against the rotor clamped on the bench.  Getting more lever arm on the wrench caused the threaded rod to BEND, and the threads in the "spider" are ruined too. It also deformed the pointed tip against the hard end of the shaft.  My puller is pretty much useless now.  Then came the creative hammering (I'd rather forget than tell you about what I did) which just broke the outer race.


Post script:  The rotor is back together now, no damage to the important stuff.  The genny isn't back up because I'm tinkering with the tower.

[bob g]

if you are concerned about it, take it to any hd truck repair shop and have the gear man look at it

he could remove that in less time than it takes to type this up.

i have taken off literally thousands of stuck brgs, some many times larger in diameter,  and some that have spin welded themselves to the shaft,,, those take a while.

cutting a groove and driving in a chisel will pop the thing and it will slide right off.

or driving it back on and cleaning the shaft up, then pull it off works well too

you got these and many other good suggestions from the guys, no hill for a climber as they say

bob g

[ruddycrazy]

Well on the subject of bearing pullers reminds me of one occasion at work where the ex employee shrunk on a tapered coupling too far on a brandnew gearbox. This coupling was about 3' diameter and it went about 10mm past the correct point on the taper as too much heat was applied to the coupling.

We got a SKF guy to come over with his hyd pump setup that is used for releasing these type of couplings, anyway after 3 hours the coupling didn't budge so I got on and made up a 4 legged puller using 30 ton enerpac puller legs. The 30 ton pack didn't budge the coupling so I went and got the 100 ton pack and put 40 ton of pressure on while the 2 of us had big heating torch's warming the outside. When the temp got to 240C the sKF guy said stand back I'm going to ramp up the tonnage to make it pop. So I quickly went behind the big lathe as I heard a big groan then BANG...... the coupling never budged but the puller not only hit the crane taking it out of action but also left a nice hole in the roof... I've never seen a guy run so quick to hide under one of the 5 ton work benchs I made and was also under as the remnants of the puller came back thru the roof.

Next day after the inquest I took this brandnew gearbox apart to get the output shaft out and it went off to get cut off which had to go interstate. All up that stuffup cost about 40K to......

[Flux]

I saw a similar one on a gearbox coupling, SKF injection gear didn't move it. They made a monster puller, heated the coupling with oxy-acetlyne, put the SKF on full pressure and started pulling with the big puller and Tangye jacks.

After the big bang there was instant delight until someone noticed that the end of the shaft was still in the coupling and not on the gearbox.

In hind sight it would have been cheaper to machine the coupling off rather than cut a new gear but it seemed the right approach at the time.

Flux

[SparWeb]

ROTFL  Thanks for the great stories guys!