Replacing gear box oil seal and bushing

[tooltalk]

Hi everyone,

I have a 4x6 bandsaw that is leaking gearbox oil around the shaft that the bottom wheel is attached to. The previous owner had grease in the gearbox, and after using it for awhile I cleaned it out and put in gear oil. Well, I quickly discovered why the other guy had grease in it, because it started leaking oil very quickly.

I took it apart today to figure out where the problem is and found a severely damaged oil seal and a plastic bushing of some sort. The dimensions are marked on the oil seal 35mmx15mmx7mm and I've found a couple sources for that, but I can't find any info on the grey plastic part seen in the pictures below. I've looked at manuals for the various 4x6 saws like the Harbor Freight, Grizzly, Jet, etc and they all seem to have similar parts, and list this item as a bushing or spacer, but none list any dimensions.

Has anyone here ever replaced this part? Mine is so damaged it's hard to tell the shape and size. It looks like it might have been tapered to fit into the oil seal, but it's hard to tell for sure. I've been searching online most of the day more details about these parts, but haven't found much. So any info or advice would be much appreciated.

Thanks.

 

[Ulma Doctor]

the shredded plastic part appears to be a spacer.
since you have the bearing OD and an approximate ID of the spacer,
if you were so inclined, you could reproduce it in delrin, steel, aluminum or other suitable material
the tapered nature of the spacer most likely was to prevent collision with the oil seal, but limit axial drift at the same time

i would put the thickest, tackiest, grease i could find and pack the housing as full as possible
grease is sufficient in an enclosed box for lubrication

 

[tooltalk]

Thanks for the quick reply. Are you suggesting not replacing the oil seal and bushing, and just packing it with grease?

 

[Ulma Doctor]

go ahead and replace the seal and spacer, then pack er' full

 

[tooltalk]

The old bearings only have shields on one side. The inside bearing closest to the brass gear is a metal shield and the outside bearing is rubber. Does it matter if the replacement bearings have rubber seals on both sides?

Thanks.

 

[Ulma Doctor]

The old bearings only have shields on one side. The inside bearing closest to the brass gear is a metal shield and the outside bearing is rubber. Does it matter if the replacement bearings have rubber seals on both sides?

Thanks.

i use 2 rubber seal almost always, the protect better than the 2 metal shields

 

[Cooter Brown]

Wow! Those Lip Seals are completely gone....
McMaster-Carr sells them....

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[tooltalk]

i use 2 rubber seal almost always, the protect better than the 2 metal shields

That makes sense. A bearing behind the gear with two rubber seals would probably prevent most of the oil from making it to the oil seal in the first place. I can't see much need to have oil moving past that bearing anyway.

Wow! Those Lip Seals are completely gone....
McMaster-Carr sells them....

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

It is strange that it got so torn up. Thanks for the link, but I found the correct seal on amazon.ca. It was a bit more expensive than some other sellers, but I purchased something else and got free shipping on everything.

 

[tooltalk]

I got the parts today and put it back together. I made a spacer out of a piece of PVC pipe coupling. It was a good fit, but I think I made it a bit too tall. There's another metal spacer behind the drive wheel and it doesn't fit now, but it will be an easy job to cut that down a bit or make a new smaller one. I had some 90w gear oil on hand, so I put that in it for now to make sure it's working and not leaking. I can always replace it with something heavier later, but it will be much better than what was in there before. Thanks again for all the advice.

 

[tooltalk]

In case someone else is looking to do a similar job, I wanted to point out that I wish I had taken some measurements such as how far the shaft protrudes from the main casting. There are no shoulders in the bearing bore or on the shaft, so there is nothing for anything to seat against and it was difficult to know where to position everything. I ended up going by feel, turning the gears by hand, and tapping the shaft back and forth to try and position everything as best as I could.