Undercarriage wear question?

I have all new undercarriage on my 931B but am wondering about wear on the bushings. With the help of a friend we welded the new sprocket teeth on and made sure everything was straight and true. The sprocket teeth were kind of a rough casting/forging. I was told they might have to wear in a bit. I'm getting a wierd tooth profile, on one side it's rounded near the tip and almost straight on the other side. I've probably only got 20 hours or so on the new tracks. I noticed today that on the front side(top carrier side looking up from underneath, bushing side toward the bucket)of the bushing, there is some wear starting. It feels like about a 1/4 inch flat spot developing just below the centerline of the bushing. I'm guessing this would be wear from going in reverse as that's where the force is put on that side of the bushing. Is this normal or should I try to get the dealer to come and look at it? I spent a small fortune on the undercarriage and don't want it to wear out faster than it should. I tightened the tracks to 2 inch sag and they got a little tighter. I used it like this for only a couple hours and then loosened them off and readjusted them. The sprockets don't pop as much as they did when first put on but still do sometimes when I turn. Also what makes the rails want to go all the over to one side on the idlers? Do they just move side to side as you use the machine and turn? I'm no expert and could use some expert advice. Thanks in advance. Dave

I have a D3B which is the dozer version of the 931B (I think). It has wide pyramid (swamp) pads and the chains spent more time on the roller flanges than on the drums. And they tended to hang on the edge of the sprocket teeth as well.

The tracks are in pretty good shape, perhaps 60%, and the rollers and sprockets are as good or better. I attributed the problem to the wide pads on the relatively rough ground I was working and to the very frequent turns.

I built inner and outer track guides with replaceable rails that have eliminated almost all the problem, and have not created noticeable wear on the chain bosses. I probably did it the hard way, but the guide supports bolt to the underside of the track frames between the rollers.

They were easy to build and easy to install once I drilled and tapped about two dozen 1/2-13 holes without removing the tracks or rollers. I spent more time on the holes than the rest of the project. In hindsight I should have just welded them on.

Be glad to take a picture and send it if it might help.

Hard to figure why the pin/bushing is riding high up on the sprocket tooth, after a new undercarriage install, it's usually associated with a worn out chain, along with other worn components, where the adjusters are all the way out, chain is loose and does not ride in the root of the sprocket teeth. You say 1 side is doing this, the other side, the sprocket teeth remain square'd at the tip off like when new.

Assuming the sprocket rims are the correct pitch for the track chain, track frames have no alignment or other related issues, I would double check the tension on the problem side, it's possible that it is too loose, which would show a wear pattern like described, a loose track chain is going to ride up high on the sprocket tooth, eventually the sprocket will slip the chain, I ran a Fiat Allis FD 30 that was so worn it would do this.

Another thing to consider is soil conditions, terrain and operating habits.

Soils like coarse sand and gravel can be abrasive, it will accelerate wear more than other soils, not much you can do there.

Terrain, if you are constantly operating on rough uneven ground, or the side of hills, slopes etc. you will notice all kinds of different wear as the track components take more abuse if one side is lower than the other like on slopes, think about the surfaces of the track components that are now pressed hard up against each other while the track is moving, more surfaces of the components now have contact.

If you saw a recent episode of Axe Men, the foreman from Gustafson Logging, was pulling some equipment up the slope with a D8H Cat, when he came to the top, the crawler came over center, onto logs and uneven ground, he was also at an angle. That is kind of worst case scenario, the extra wear is one thing, but he also let the nose come down a little too hard for my liking, came down hard, have an operator constantly do these kind of things and see what kind of problems arise on the track frames, lot of weight and forces at work. He still had that skidder in tow, if the line was tight, could have pivoted him right around, hope he had the seatbelt on too, nose over like that and you'll end up on the hood, saw an inexperienced forman do that early one morning, the stack kept him from ending up over the nose behind the blade.

Operating habits, has a lot to do with wear, spent a lot of time on 977L's and 955's of the same era, loading trucks and lot of other oddball work. When loading trucks I would try to make a gentle K pattern to the pile, turns were subtle not sharp, but if that was all you did, no doubt one side would have different wear pattern, could be a lot more than the other side, it's good to change directions or sides when doing cycle type of work like loading trucks, more preferrable to use a wheel loader than a crawler for this work.


The flat spot on the bottom of the pin, that is the wear area from the sprocket, hard to say whether the wear rate you are getting is normal or accelerated, typically as I remember from running D3's you would get 1200 or so hours on them before you took the tracks off and had a pin bushing turn done to the new wear surface.

You may want to ask Oz Dozer along with others on the ACMOC/ACME forums, might help with some of these specific issues you describe, especially any track frame or component aligment issues, he's also got quite a bit of undercarriage specifications and cross reference information.

When I said one side is wearing different, I meant on the sprocket teeth. Both sprockets are wearing the same way. I'll try to describe it better. If you look straight at the sprockets from the the root, The side toward the rear of the machine is almost a straight line from the root to the tip and the side toward the front goes straight about 3/4 of the way then is rounded to the tip. This rounded side is the side that is starting to just show a flat spot on the bushing. I assumed from driving in reverse? I think I'll try running the tracks just a little tighter. I read that loose tracks can cause accelerated wear in reverse that is more than normal. Dave

I only have 14 inch street pads. I've read that track guides/rock guards cause increased wear because they don't let the mud and dirt come out. My track guides on the machine aren't in very good shape but I thought with the new rollers everything should stay lined up pretty good. I don't know if track guides would affect sprocket and bushing wear. Dave

Yes, see what you are saying about both sides coming up from the root. There is a reason why running in reverse causes more wear than forward, this was explained to me once, obviously just the pin/bushings, specifically the exposed part that contacts the sprocket, I'd have to take a re-fresher on the specifics of that. Track type tractors used for drawbar work, like ag applications do not have the same U/C wear rates as dozer or construction type applications, not nearly as much reversing and turning when used for ag work, definitely some truth to comparing wear rates between the two applications.

That flat spot is the contact area and is subject to wear, and is also why at 1200 hours or so, depending on several variables, it used to be common to turn 180 deg to a fresh surface, still need to be within tolerance on the rail height and not have excessive internal wear causing the chain to have more slack.

I think the best course of action is to make sure the track tension is correct, and abide by as good of operating habits as conditions permit, running hard you may only get 1000 hours before they need to be turned, maybe even less in some instances, but best to turn em when needed too, lot of things to monitor and do to get max U/C life.

I put salt rails on. Very hard to find a track shop that will turn pins and bushings anymore. They're too busy! Maybe they'll wear in and then not wear so much after that. I'm working mostly in clay but mud and stuff sometimes. I can't always spin around and go forward when I'm hauling bucket fulls of dirt. I'm wondering if I should get the place I bought the tracks from to have a look. I didn't think I'd see wear this fast on the bushings. The sprockets, kind of. They weren't square from the beginning so I figured they'd wear in and the dealer agreed. Maybe the sprockets and bushings just wear in together initially? Too expensive to not worry about it. Dave

Dave,
Do you know the source of the track gear you bought?
Some stuff out of Asia is good...some is rubbish.
Jim

If you can feel/see a flat spot on your bushings after only 20 hours, then I'd say you have a problem. Have the dealer look at them as soon as possible - you may have got a bad set of bushings.
srs_mn

The distributor is right here. The undercarriage is Trek, made in Korea. I think the bushings are OK. The sprockets I think were cast a little bit off. I've got maybe 50 hours on the undercarriage but about half of that is digging with the hoe which shouldn't cause any wear on the undercarriage. There is supposed to be a 3 year/4000 hr. warrantee on the undercarriage. Pro-rated of course but I wouldn't think 50 hrs. should count as much use. Dave

If you are getting a flat spot on the bushes after such a short time it sounds to me that the pitch or teeth is not right,has your sprocket got a hunting tooth i.e an uneven number of teeth,if it has and one tooth was out of profile it can mark every bush in the chain,look at the sprocket and see if you have a tooth that is higher than the rest,if you find one give it a shot of the grinder,with new sprocket rims the tooth tips should not be making contact yet with the bushes,with the price of undercarriage you do not want it wearing that fast.
AJ

25 tooth sprocket. It's almost like the sprocket rim was cast slightly over/under size and the needs to wear in. It is better than when first installed but I don't think it's right. I think I should get a nice tooth profile on both sides? I also think the tips of the teeth might be slightly too high? When I installed the tracks, the bushings sat in the root on the top of the sprocket but on the bottom, the bushing was inline with the tip of the tooth. I'm out in the field and sure hope I don't have to change sprocket rims again. I spent around $8000 on the undercarrige so I'm not going to just keep wearing it out if there's a problem. Dave

if at the top of sprocket, bushing is in the root of sprocket, but at the bottom it's lining up with the tip, i would say the pitch of chain (distance from center of bushing to center of next bushing) does not match sprocket.