Please help with 955L final drive outer support bearing

[OldandWorn]

This may be difficult to describe and a bit winded so I hope the pics will help. When I was greasing the outer sproket axle support on the left hand side I noticed that the grease was just oozing out of the crack and not seeming to stay inside like it did on the right hand side. I removed the 5 bolts to take the cover off and noticed that the outer housing which is attatched to the track rail was egg shaped, meaning there was no clearance at the bottom but a larger gap on top. I looked at my parts manual and noticed the 2 o-rings that seal the outer and inner parts and understand now why the grease was oozing out at the top. Either because of damaged o-rings or there is now too much clearance on top to seal properly.

What I didn't understand is how 2 parts that normally don't move could get worn out like that. I watched the inner hub while the machine was moving and noticed the part was moving up and down about 1/8" per revolution of the sproket. The inner part is what holds the tapered roller bearing which supports the outermost part of the sproket shaft.

1) Is it possible that my sproket shaft is bent? What else could cause the hub to move up and down with sproket rotation?

2) Does that grease fitting only grease between the hub and rail support or does it supply grease to the outer tapered roller bearing also. Looking at the cutaway drawing in the service and parts manual I don't see a path for the grease to get to the tapered roller bearing.

3) A couple ounces of final drive oil dripped out when I took the cover off of the inner hub. Normal?

4) The washer behind the BIG nut has a lateral crack in it.

Thanks for any help!

 

[Komatsu 150]

Sad to say it but you have a serious problem that needs to be looked at. It might just be a bearing issue but if you keep going and do gear damage could get real expensive.

 

[bill onthehill]

Have to wonder if it was dropped off the side of a trailer at some point in it's life.

 

[OldandWorn]

Yup! The sproket shaft is short and stout and if in fact it's bent would mean an aweful lot of force. Now that you mention it, I can see how the washer behind the nut could be cracked. Right behind the washer is the tapered roller bearing and it would want to push outwards with a large shock load.

There is a local 955L being parted out, maybe I should check for a shaft. Problem is, are all of the large tools and hydraulic rams required to change the shaft out. The manual says to support a large breaker bar on the floor and put the machine in gear to loosen the big nut. Sounds kinda scary to me. 1200 ft lbs on the nut to seat the bearing then back off 2/3 of a turn for install.

 

[Komatsu 150]

I've never been inside that area of our L but I find it really hard to believe a bent shaft as they are so stout. Get it up in the air and do some pushing, prying, or jacking on the sprocket. Better yet split the track. It's pretty easy. In the old days it was common to use a slug wrench for sprocket nuts. Hard to get it right unless the mechanic was experienced. Our Cat dealer has no problem sending a service truck just to do something like that. I had them out just to change a crank seal on truck and we did the rest of the work.

 

[OldandWorn]

Great idea Komatsu! That's like renting a tool and having an experienced operator come with it.

What is a slug wrench?

 

[Komatsu 150]

One of these, just hit it with a big hammer.

 

[Komatsu 150]

Someone who's worked on on these would know specifically but our older machines also required a large hydraulic puller to get the sprocket off the shaft, on the 955 I don't know never having been in there.

 

[Lee-online]

The shafts are pretty stout and i haven't seen any bent but they could be. I have seen the case cracked due to side loading on and off trailers and still the shafts were ok. Are the duo cone seals leaking?

Check the side frame to make sure all the mounting bolts are tight.

Disassembling the sprocket, shaft and finals takes alot of tooling. The sprocket is pressed on with 40 tons.

 

[OldandWorn]

There is no hint of leakage on either side of the sprocket. I must say though, the final drives are the only fluids that I haven't checked because I don't have a tool to get the plugs out yet. The PO was very meticulous and all other fluids were full and clean.

I can check the track frame mounting bolts.

The eccentric movement of the outer bearing hub (between 1/16 and 1/8") and has gone on long enough to slightly wear the outer support that is bolted to the track frame.

Lee, would you happen to know how the outer tapered bearing gets lubricated? Grease from the fitting or final drive oil?

The first thing I did after getting the machine was to buy service and parts manuals. I read about and saw pics all of the tools that are needed....arrrg!

 

[tctractors]

Lee is on the right line with the wayward F/Drive, the usual cause of problems to the outer bearing is the track frame bolts coming loose or missing, first check is the bolts on the hard bar, then the 4 bolts around the back end, the track frames are shimmed up to align them, the shim pack area is usualy the first place to have bolt problems, the dead shaft is not realy found bent on these loaders, but they can have damage on the outer key way area, its a 4 gear final drive setup with a top pinion, intermediate gear set, then finaly the large bull gear, the outer hub is mounted onto the dead shaft and held with a large half moon key to stop it rotating, first thing to do is drain the F/D oil looking for bits of iron, if you find none I would just try tightening the outer nut up firm, track off is best but no big deal to leave it on just make sure its jacked up and blocked clear of the floor, the CAT talk thing can be made easy by, tightening the nut with a good sized truck wheel nut torque wrench to about 600Nm will load the bearing, forget all that 1200ft lb stuff thats for new bits, then spin the track and recheck the torque on the outer nut, it might be worth doing the other side at this time as well, this keeps the bearings pre-loaded, the oil you found in the cap is a bonus I often only found dust, things might not be as bad as you thought, if it is a knacker job lets hope the top pinion is like new as that realy means to me that you have to do both sides to make it worth while ( well thats how my brain operates)

wishing you the best of luck tctractors

 

[tctractors]

One more tip is if you dont have a socket of the correct size make one out of flat strip or what have you, 600Nm is about 3ft 6" bar dogged firm but dont go crazy.

 

[OldandWorn]

Thanks for your time and input TC. I can collect up enough tools to check most of the points that you mentioned. If the hub will slip off of the dead shaft fairly easily I may be able to inspect the outer bearing as well. From the wear pattern (time of operation in this condition) and the relatively slight movement compared to the size of the bits, I don't feel this is being destructive to the final drive gears although I'm very curious as to what is causing this and will fix it if I can.

At this point I'm more concerned that the outer bearing is getting proper lubrication and the reason for the cracked washer behind the dead shaft nut. I can't see the lubrication path from the engineering drawing in the manual. If the tapered outer bearing gets lubricated from the grease fitting I need to come up with a plan because the grease just oozes out of the worn crack to the outside of the machine.

Yes, the 1200ft lbs is for seating only and I think the final torque is somewhere between 400 and 500 which is right on with your 600Nm figure. The dead shaft nut is recessed into the hub so a standard socket will be needed.

"if it is a knacker job lets hope the top pinion is like new as that realy means to me that you have to do both sides to make it worth while ( well thats how my brain operates)"
Sorry....I'm totally lost on a knacker job and the rest of this sentence.
Translate please?

BTW....This is a hobby machine and its only use right now is to put a very large grin on my face but I will get around to the service before I work it. I have a huge powerline project I'm in the middle of at the moment.

Thanks again for your help

 

[OldandWorn]

Oh, one other clue I just thought of. The hub assembly on this side sits out farther. You can see the gap in the pic. The other "good" side is flush with the rail support casting.

 

[tctractors]

O&W, a knacker job is when thing are smashed up, done in, worn out, or just knackered, to change the top pinion is a good bit of work that once you start you always strip out both sides (Final Drives), the important thing is you have a parts /service manual so you can see how things are built up, the outer support that bolts to the track frame has a replaceable sleeve bearing in it if I remember, nothing moves on the nut side of the dead shaft, grease is added realy just to push out water and create a protective barrier,when you remove the outer cap on a well maintained shovel (955) it would be common to find oil at the nut, this oil travels out around the key way area, its nothing to get a panic about, its only a small amount and stops things going rusty

 

[Komatsu 150]

I might add that it's real common for those fittings not to take grease and the service people have always been unconcerned about it.

 

[OldandWorn]

I might add that it's real common for those fittings not to take grease and the service people have always been unconcerned about it.

Thanks!

 

[OldandWorn]

when you remove the outer cap on a well maintained shovel (955) it would be common to find oil at the nut, this oil travels out around the key way area, its nothing to get a panic about, its only a small amount and stops things going rusty

I like seeing oil in there. If oil can find its way into the hub there could be a chance oil is getting to the outside tapered roller bearing as well.