Bearing replacement question
- Thread starter XTREEC
- Start date
Reach
Been here much more than a while
- Location
- Atglen, PA
Drum bearing? Yes, replace them both. If you don't, you'll have to replace the other one soon anyway. And as much work as it is to take the drum out, you'll save money in the long run.
Reach
Been here much more than a while
- Location
- Atglen, PA
What chipper is that, anyway? That does not look like a very heavy drum bearing to me.
Morbark Twister 12. Well used.
Thanks. I’m hoping removing the drum isn’t as bad as lifting the upper feed wheel for bushings.
Evo
Been here much more than a while
- Location
- My Island, WA
@Reach do you need to remove the drum? Can’t you just support the weight and take slack out with a chain hoist to replace the bearings?
But 100% replace both sides while your in it.
But 100% replace both sides while your in it.
Reach
Been here much more than a while
- Location
- Atglen, PA
It might be possible to change the bearings without removing the drum altogether, but it is certainly easier in my opinion to cut the old bearings off and clean the shafts to put the new bearings on if the drum is not in the chipper.
Looks like that chipper has to have the bearings removed altogether to get the drum out though, due to the way they are installed. I suspect that getting the bearings off of that shaft is going to be quite a fight. Bandit builds there so that you can unbolt the pillow blocks and lift the drum out with the bearings installed, I think it is a much better design than what I see in that picture.
To what Reach said, I've seen many vids where mechanics try to force a bearing or component off an uncleaned, corroded, dented, keyway channel edge bashed etc shaft and had a big fight or failure. Where possible/needed a pristine deburring, de bumping, diameter high spot removal prep, cleaning polishing and light lube (WD40) makes removal more viable. If that route is contra-indicated, cut the bearing off first prep the shaft second would be the pragmatic method.
Don't forget to avoid applying installation load to the roller elements as it can ruin the roundness of the rollers or dent the raceway surfaces - premature failure. A pipe contacting only the inner race is good for installation. Also beware of installed preloads as you tighten it down, again premature failure. To that end bearings often have self alignment ie pillow block and big clearance bolt holes but flange mount can't take up alignment/preload axially along the shaft direction.
Looking at that pic of a flange bearing locked into chassis retainer ridges it would seem to me that there must be some give somewhere along that assembly to allow the bearing to clear those ridges. Maybe on the other end? Maybe the drum is not locked axially wise to the bearing and floats with end thrust "guiding"?
Don't forget to avoid applying installation load to the roller elements as it can ruin the roundness of the rollers or dent the raceway surfaces - premature failure. A pipe contacting only the inner race is good for installation. Also beware of installed preloads as you tighten it down, again premature failure. To that end bearings often have self alignment ie pillow block and big clearance bolt holes but flange mount can't take up alignment/preload axially along the shaft direction.
Looking at that pic of a flange bearing locked into chassis retainer ridges it would seem to me that there must be some give somewhere along that assembly to allow the bearing to clear those ridges. Maybe on the other end? Maybe the drum is not locked axially wise to the bearing and floats with end thrust "guiding"?
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I think if I loosen the collar and the flange the drum will slide straight up and out. I’ll have to remove the chute first. This picture shows it a little clearer. My local dealer had the bearings so I’ll get after it once the rain stops
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Situation looks much better, seeing the bearings on the outside structure face. Looks like a candidate for belts/pulley off, prep shaft, pull bearing. You don't have to be gentle on a bearing you're throwing away.
Vernier works good for finding dia high spots. Also gentle sliding the new bearing will create a shiny point on contacting a high bump, but don't get it stuck! Slide bearing back off, address high point, try to get a bit further, wash rinse repeat.
Vernier works good for finding dia high spots. Also gentle sliding the new bearing will create a shiny point on contacting a high bump, but don't get it stuck! Slide bearing back off, address high point, try to get a bit further, wash rinse repeat.
Reach
Been here much more than a while
- Location
- Atglen, PA
Looks like somebody got a little overzealous with a cutting torch taking off the last bad bearing. The factory certainly did not do all of that damage.
How many hours does that chipper have? We just replaced drum bearings for the first time ever on a chipper, and the machine had 8500 hours.
If the bearing fits tightly and clamps down securely, I would go ahead and use that shaft. It doesn't look like the gauges are that bad, they should not affect the way the bearing runs.
New bearings went onto the shaft without a problem. I think the previously seized bearing also grooved the shaft a bit. The machine isn’t worth putting in a new shaft. I’m tempted to unbolt the bushings at the drum to see if I can slide the shaft a slight amount to the right side. May not be worth it. The drum is mounted and spins freely by hand.
Reach
Been here much more than a while
- Location
- Atglen, PA
If the drum is centered in the housing, leave it be. You don't want to offset it to try to get out of that groove unless it's truly necessary.
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