New chains popping on D3

Old Magnet · Jan 15, 2016

We're not there to actually see whats going on but from that last picture things don't look to be off!!!!
For a mismatched combination I was expecting to see bushings to be oversize for the sprocket pockets.
What do other eyes see?

Scrub Puller · Jan 15, 2016

Yair . . .

from that last picture things don't look to be off!!!!

They were my initial thoughts too Old Magnet but on reflection perhaps the teeth appear a little low? . . . I seem to remember they normally come about halfway up the bush when new.

If that chain is tight around the sprocket that last bush looks to have only about a third contact. As you say difficult to tell from photos.

I would love to see those chains running with tractor jacked up on blade and rippers.

Cheers.

lantraxco · Jan 15, 2016

The top two bushings there, see the gap between the front tooth and the bushing? It's riding up the backside tooth rather than sit down into the cup.

Nige · Jan 15, 2016

I'm with lantraxco, something's off in that the bushes don't appear to be sitting low enough in the sprocket teeth.

Old Magnet · Jan 15, 2016

Yes I saw that too but was wondering which direction the track tension was coming from.

Old Magnet · Jan 15, 2016

Used to be you could get wear template patterns for checking sprocket tooth wear. Are they available for the D3?

Nige · Jan 15, 2016

Old Magnet said:
Used to be you could get wear template patterns for checking sprocket tooth wear. Are they available for the D3?

They're part of the CTS Service Kit. Can't remember the Part Number off hand but if you can find the P/N of the kit it'll be in the breakdown of that number.

dblaneyfan · Jan 15, 2016

What part numbers are on your receipt? Mayhaps a dealer here might verify the correct rails/sprockets on this machine.

Willie B · Jan 15, 2016

Is it possible the same diameter sprocket with bigger gullets is being used. Would this not change the pitch of the gullet spacing?

pineywoodsman01 · Jan 15, 2016

Here's some side view's that better show whats happening, I stopped it in forward, if I had stopped in reverse, the bushing popping would be at the top, from a mechanical perspective, I don't see how it could be anything but a chain/sprocket mismatch, but I'll admit this is the only dozer I've worked on, I'll know for sure in a few days, these chains are off and sitting on a pallet waiting for the replacements, at least I'm getting some good hard work to do, I'm recently retired from office life and just about live outside now and loving it, these chains are a little awkward when its just you though, but as they say, no pain no gain, just try to work smart.

Old Magnet · Jan 15, 2016

Only thing I can think of is that those large diameter bushings belong on segmented sprockets like the Undercarriage Manual says but so far we have not been able to determine what the difference in dimensions might be. A good track shop or Cat dealer ought to be able to sort it out.

oarwhat · Jan 16, 2016

8k bill said:
Some of the crap coming out of Asia at the moment is shocking. I wouldn't be surprised if you got a tape out and measure across the tips of the sprocket you'd get different numbers, fairdinkum the stuff I've seen you would only use for net weights. I guess it's the old saying ,you get what you've paid for. But it does look like a mismatch chain and sprocket tho. Bill.

I agree with 8K Bill. Look at his first picture of the sprocket. It looks like the sprocket has different spacing between the tips. Also those teeth just don't look right!!

Willie B · Jan 16, 2016

Circumference is different from a multiple of pitch. In example, the dimension is a multi sided figure rather than a circle. The dimension of the figure is the radius of the base of the gullet plus half the diameter of a track bushing. From one point approximately in the center of one gullet to the center of the next gullet measured in a straight line must match the pitch of the track. The straight line 25 times to go around the sprocket will total less than circle circumference.

It'd be easier if I were smart enough to post a drawing. Hypothetically; it is 14" radius to the base of a gullet from center. The bushing is 2.1" diameter, therefore its radius is 1.05 14+1.05=15.05.

If your sprocket has 25 gullets the angle is 360/25=14.4 degrees. Here's where I need to brush up on trigonometry, we can calculate the pitch of the sprocket with this much information. It would be approximately 3.7824864. Less, as straight line distance is less than curved arc distance.

Willie

Willie B · Jan 16, 2016

I found LAW OF COSINES. What is the distance from hub center to bottom of gullet? How many teeth, I guess 27 from picture, but can't easily count.

old-iron-habit · Jan 16, 2016

With the tracks off, measure each sprocket segment to insure they are equal before you install the new rails. Easy to do with them off and can give you piece of mind that the sprockets are manufactured correctly.

lantraxco · Jan 16, 2016

Not to be rude, but you guys are overthinking this. The pitch and pitch circle don't change, but making the bushings bigger means the bottom of the gullet needs to be lower, closer to the center point, so the center of the track pins align with the pitch circle. The whole sprocket will probably be smaller in diameter so the tooth points don't drag on the bushings as they enter and exit. If you had a segment to hold up against the old style rim you would probably see right away the difference between them.

8k bill · Jan 16, 2016

:iagreeIf that chain and sprocket was on a high trac design it would work. That's why on a conventional low sprocket the lead in angles on the teeth are wider. That chain with the big bushings does not belong with that sprocket. Bill

ETMF 58 White · Jan 17, 2016

I'm going to put a new undercarriage on my Kobelco 210 this winter and several guys have told me that there is a track dealer in Pittsburg that will have the best prices on aftermarket and also they have a very good shop. Although I plan to do the work in my shop, I want to be sold the correct parts. Now I'm reconsidering going to Texas to buy the parts on the chance that that is where you got the D3 parts that are giving you trouble. I know that's just an outside chance, and Texas is a big place with lots of track dealers, but your "piney woods" handle does narrow it down to the eastern half of Texas, no? One good thing about doing business in Texas is that the state promotes the agri and timber industry by giving a sales tax exemption to producers of farm and timber products even if they are domiciled out-of-state.

lantraxco · Jan 17, 2016

You shouldn't have issues with a Kobelco getting the right parts, the problem with this CAT D3 is that CAT has used three different dimensions of bushings over the years and still offers all of them as replacements. The average parts/undercarriage guy won't be aware that sprocket "A" won't match with bushing "B", at least until the first time he tries it.

ETMF 58 White · Jan 17, 2016

lantraxco said:
You shouldn't have issues with a Kobelco getting the right parts, the problem with this CAT D3 is that CAT has used three different dimensions of bushings over the years and still offers all of them as replacements. The average parts/undercarriage guy won't be aware that sprocket "A" won't match with bushing "B", at least until the first time he tries it.

That makes me feel better then. It's pretty obvious that Piney Woods got some mismatched parts as diagnosed by lots of experienced guys on this site. The thing that rubs me and everyone else wrong is the dealer came up with the new springs as a fix, when in reality that probably had little to do with it. But one thing I've learned over the years is that dealers will keep throwing parts at a machine as long as you keep paying them. I had one put a new turbo on a C-12 because he couldn't get the $5 gasket on the return oil line to quit leaking. A $1500 turbo replacement didn't stop the leak either, but me taking the tube off and straightening it in my vise and putting it back with a new gasket did the trick.

Apologies to the OP for getting the thread off track. Back to the D3 ongoing saga-- keep us posted how it turns out, Piney Woods!

New chains popping on D3

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