Cat Hydraulic Cylinder Bearing removal ?

[nonprod]

Hello Folks,

This seems like a stupid question, but I was looking at my Cat Thumb cylinder (268-8225) the other day, and the bearings in both eyes spin and slide around, and have more ovality in the eye bores than I want to see - But the question is: How to remove the bearings? They move out of the eye about 1/4" on one side but they clearly hit something which keeps them from sliding out. The drawing shows the zerk drilling, but no bush retaining pin or other obstacle. Does this mean the zerk threads were not cut into the eye but some sort of pressed in tube, like a long helicoil and that's what the bushing is hitting when you try to slide it out of the eye? Am I crazy and an equipment manufacturer doesn't want you to replace a bearing....!?

TIA - gibbs

 

[Nige]

Run a few rings of weld circumferentially around the inside diameter of the bearing and let them cool. After that it should almost drop out. If that fails then you need an FBH.

 

[nonprod]

Ah, this idea would conceivably remove the bearing, but destroy it, no? And what is an FBH in this context?
From my preliminary glance, the eye is out of round, that is, the hardened bearing rocks no more on the pin than expected. Am I off base by assuming that the bearing is to have interference fit in the eye, and the pin is the object to move?

thanks for your comments.

 

[Mobiltech]

The bearing may have a grease groove around the circumference which probably left an area in the bore with no wear. When the bearing hits that unworn spot it gets tight .
BFH. Big farkin hammer.

 

[nonprod]

I do think there is grease groove on the bush. I stopped short of bashing it with a hammer, because the bush stops moving out with a pretty solid clunk noise.

 

[Nige]

Bearing should be an interference fit in the rod eye. Normally somewhere about 0.001” of interference per inch of bore size.

If the bush moves laterally in the bore both of them are by now toast. Extract the bush and scrap it, have rod eye welded and bored back to standard size, install a new bush and Bob’s your father’s brother.

FBH = F**kin Big Hammer

 

[nonprod]

Thanks all. Update: I was just being coy because of the distinct ring the bush made when it hit a crazy ridge in the middle of the bore. I made up a drift and knocked the bush without the biggest sledge. The bore's a mess; yet another line to bore. There adding up! Good thing the machine was relatively inexpensive... ...when I asked the guy I got it from: "Are 3000 of the 4000 hours on this with a breaker?" he said no, of course, but it looks like his op thought the thumb was a breaker.

 

[Nige]

Reminds me of one of my old man's mantras when it came to knocking pins or bushes out.
(Michale Caine accent) - "You're supposed to HIT the f'kin thing, not tickle it."

 

[kshansen]

A little OT but the reference to FBH reminded me of a bearing seminar I went to many years ago. Instructor told about giving his talk and using that term "FBH". When he was asked by a young lady he had forgot was in the class what "FBH" stood for when talking about installing a bearing he hesitated for a second and said "That's the Fafner Bearing Handbook!" where you can look up the tolerances for fitting a bearing in a housing!