Its the number of teeth on the sprocket And any more they are almost all odd. the number of chain links don't.
Bob
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D8H undercarriage replacement advice.
- Thread starter D8HCattle
- Start date
Bob
That is a even tooth sprocket a true double pitch sprocket.
When the track stretched to the end of the adjuster one link could be removed.
Bob
DMiller
Senior Member
Chains don’t stretch they wear and expand. Pins to bushings grind into each other and increase the distance pin to pin. If managed to get to a full link of wear are well beyond design life risking throwing rails at bad times putting too much side stress on rollers or idlers and sprockets or just breaking pins or link ends. Harder on machine than not unless running it into destruction.
Track wear is a science in it's self.
If you are talking a newer production machine verses a homeowner lots of difference .
A D 8 track link 9 inch pitch sealed track at 100% worn is a 1/2" over 4 pins.
You stretch the track to take this measurement.
A 7 roller chain is 41 links so total wear is 5 inches.
That's well within adjuster range.
when the tracks are at 150% the wear is at 1 inch so 10 inches will allow a link to be removed .
This is a homeowner fix to keep from buying $50 thousand in parts.
generally pins wear twice as fast as links.
All that said short tracking is more often done on excavator tracks on mid size machines .
Bob
John C.
Senior Member
If you have SALT tracks, there is little to no internal wear between the bushings and pin. What little bit of adjustment that you have to do is from the external wear on the bushing and the throats between the sprocket teeth plus the wear on the idlers. Side wear on the rollers and idlers is almost always from the track frames being out of alignment with the sprockets. Worn chains usually equate to all the rest of the components to have the same amount of wear. Lots of people talk about pulling a link, but few ever do it.
Hey, here's a question for you guys. I've never had anything to do with high-drives, but a guy i know who's owned various dozers told me the high-drives are harder on segments and rails because the rails only wrap around the sprockets approx 100 degrees as opposed to low-drives which are approx 180 degrees. So, given the same operating conditions, and SALT rails, on the same size and weight machine, is he right? Theoretically he should be right. Is there a vast difference between service life of the two types( high-drive compared to low-drive)?
John C.
Senior Member
The people selling the stuff years ago pushed the theory that only three teeth exerted a pull on the chain no matter which type of drive. The quality of the metallurgy on chains made today has largely made any arguments moot. That and the fact that they make the bushings thicker. High drive stuff lasts as long and any conventional drive stuff. It does cost more up front and in cost per hour.
What isn't addressed is the double idlers on high drive undercarriage and the additional wear being put on the rails of the links. Look at any worn high drive chains and you will see a belly worn in the middle of the links. Two idlers means double the wear per revolution of the chains. It is a big reason Cat is trying to push the System 1 undercarriage over the conventional SALT undercarriage.
What isn't addressed is the double idlers on high drive undercarriage and the additional wear being put on the rails of the links. Look at any worn high drive chains and you will see a belly worn in the middle of the links. Two idlers means double the wear per revolution of the chains. It is a big reason Cat is trying to push the System 1 undercarriage over the conventional SALT undercarriage.
Seeing as how the rails don't touch a drive sprocket that is a no starter.
The bushings have a shorter wear pattern but the plus to this is they can be turned twice on bigger tractors.
I thought Cat gave up on system 1 on big tractors some time ago?
And the big tracks are made in heavy duty versions as are bushings.
Like I said there are dozens of factors on track life.
Bob
I didn't find it an easy job .With the right gear for removing pins be easier .Then there was the moment of doubt about the tracks being long enough after the links off and in bits .
I got most of the new undercarriage from various equipment auctions and sellers who had them as spares for their D8.. I figured my stuff was pretty worn out. Since I got a complete undercarriage I might as well replace it all. And start fresh again. See pictures for what my machine looks like now. Bottom roller are hidden behind rock guard… they appear to have similar wear. Pin are exposed…. Bushing worn through
