How I Ruined a Chipper Disc Bearing

[Merle Nelson]

On a Bandit 90XP I let the "front" chipper disc bearing's (the one closest to the feed table) dust cap fill up with excess grease pumped into it over the years - 700 hrs of use. Once filled near the bottom first it closed a crack between the bearing housing and the dust cover which now allowed it to retain water when it rained. As it progressed and over time got worse the water in there mixed with grease and soon enough my bearing was spinning in a milkshake of watery fluid more than coated in grease. Started hearing a crunchy sound when I rotated the disc by hand.

Fix is to pull dust cap off and remove excess grease allowing continued drainage of water out when it rains. Hope this saves someone some grief. I'll review and see if I can add some pictures.

 

[Brando CalPankian]

On a Bandit 90XP I let the "front" chipper disc bearing's (the one closest to the feed table) dust cap fill up with excess grease pumped into it over the years - 700 hrs of use. Once filled near the bottom first it closed a crack between the bearing housing and the dust cover which now allowed it to retain water when it rained. As it progressed and over time got worse the water in there mixed with grease and soon enough my bearing was spinning in a milkshake of watery fluid more than coated in grease. Started hearing a crunchy sound when I rotated the disc by hand.

Fix is to pull dust cap off and remove excess grease allowing continued drainage of water out when it rains. Hope this saves someone some grief. I'll review and see if I can add some pictures.

What grease were you using?

 

[Merle Nelson]

Mystik JT - 6, High Temp.

That didn't have a lot of staying power on things like the flat surfaces of my chipper chute so I switched over to Lucas Red N Tacky

 

[Merle Nelson]

Zip tie shows the gap that water could drain straight out if not allowed to plug with grease.

 

[Merle Nelson]

 

[Merle Nelson]

I didn't think to take a picture of this when I first opened it and it was packed with mushy grease. But here it is showing some rust including pitting rust that's been working in there for some time.

Guess I'll pull the dust cover again soon to check torque and then go to every oil change to wipe out excess build up near seam/crack.

 

[Brando CalPankian]

View attachment 92828
I didn't think to take a picture of this when I first opened it and it was packed with mushy grease. But here it is showing some rust including pitting rust that's been working in there for some time.

Guess I'll pull the dust cover again soon to check torque and then go to every oil change to wipe out excess build up near seam/crack.

Good to know.

 

[evo]

My 12xpc doesn’t have a dust cap, neither does my gravely.
I think I recall one on the 2010 90xp I ran and it was plastic.
I’ve always greased daily and if excess built up used a putty knife to swipe it.
I’m wonder if there would be any harm in just keeping it off?

 

[Merle Nelson]

Yeah, doesn't really seem like there would be. Feed wheels have same configuration of bearing exposed. Other side of disc shaft has a similar bearing only protected by being shaded by belt/pulley guard but exposed to copious dust.

 

[flushcut]

Bummer! May the repair be easy and cheap.

 

[evo]

Bummer! May the repair be easy and cheap.

If it’s the outside non pulley it should be fairly cheap and easy. The hard part will be supporting the weight, a chain fall hoist would be easiest but an 4x4 and a bottle jack or blocks and wedges will be fine too. Open up the inspection flap and take the outfeed shoot off. Loop some chain around the inner part of the shaft on the bearing that is to be removed. The bearing itself just has a set screw on the shaft, and four mounting bolts.
Just make damn sure the set screw hasn’t spun and marred the shaft (mine did and the bearing was impossible to get off!)
If the bearing is fighting you weld some threaded rod to the putter part and get some square tubing. Drill three holes (for the two welded threaded rods, and one in the center.) bolt the square tubing on and insert some threaded rod in the center hole. Add a little heat to the inner race and slid it right off with your makeshift bearing puller.

 

[Bart_]

May I suggest drilling drainage holes in the bottom of the cover. The amount (pumps) of grease could be calibrated so the excess doesn't build up so fast if you see it overflow with the cover off. There isn't that much room inside a bearing and accomplishing a complete grease flush every day is questionable to do and in need for. At rpm and temp overfill just gets expelled anyway.

A quick shot of wd40 up the drainage holes would confirm if they're plugged and possibly help rinse out any moisture.


If you've achieved rusted on, check out Taryl Fixes heat shock method to break it free.

ps not sure if its a factory only bearing or you can read the bearing number off it still, but check into getting the rubber seals version if your current bearing is only metal shields. overflow grease will still come out rubber seals too

 

[Merle Nelson]

Done, thanks.

 

[Treemuel]

Thanks for posting this. I opened up the cover on my recently acquired Bandit 150 and extracted about two cups of old grease! Fortunately doesn't seem to have done any damage to the bearing; just some surface rust inside the cover.

 

[Bart_]

One of a number of such charts on the interscreen:

Grease Compatibility Chart and Reference Guide

When it comes to lubrication in industrial plants, most maintenance people strive for consistency – the use of the same products over a long period of time. This generally allows for smooth...

www.machinerylubrication.com

I shy away from any grease who's ingredients are not published.

 

[Merle Nelson]

Bump. Just put on new knives and checked the dust cap. Grease build up was blocking water exit and starting to effect the composition of accumulated grease.

I'll check it every knife and oil change now.

Edit: So I think this is applicable to disc chippers with a dust cap over bearing.