JD 350 Track Adjuster

[Stan Disbrow]

Hi,

The link-to-link center spacing is growing longer with time and wear. So, now the force on the chains is causing the bushing to slide up the side of the sprocket teeth. This accelerates wear on the teeth. The bushing is supposed to turn within the root of the tooth, but now it is sliding up the sides. This leads to a wallowed out root and pointed teeth. Eventually, it will start jumping teeth under load.

The adjustment is designed so that when it runs out, it is time to replace the chains. Removing a link allows you to return the adjustment back to the beginning, but the overly long link-to-link spacing remains. This will wear the sprocket teeth too far and require new sprockets later on.

Additional wear occurs inside the bushing and the outer part of the pin. This leads to track 'snake' which wears the front idler. So, dropping a link now means new idlers later.

And then there is wear in several areas of the actual links and the bottom rollers. So, these are a good thing to replace as well. And pretty much mandatory after running things with a link removed.

Here is a link to a PDF regarding undercarriage.

https://www.tpaktopc.net/files/undrcarguide.pdf

It is a Dresser, not a Deere, document but it all works the same way.

It will refer to Sealed and Lubricated rails, which is an option when buying new ones. I haven't shopped for rails for a long time, so it may well be that that is all which is available these days.

Stan

[Kolot]

Great explanation, in the end after wear like running the wrong pitch chain on a saw, it goes round but does not hit properly on the sprockets , correct?
Also when you say rails I was thinking the track bar frames,
Do rails refer to the chains, links?

[Stan Disbrow]

Hi,

The rails are the chains and pads.

The original name for a crawler was Tracklayer. More akin to a train than a cart, running on rails rather than directly on the ground. The rails can't be solid like with a train because they have to be picked up and laid back down in front of the machine. So, they use links instead.

There were some odd terms, as we think of them today, for things way back when. Such as Traction Engine rather than Tractor and so on.

So, you will see the terms Rails, Chains and Tracks used interchangeably. The rollers and idlers and sprockets when considered with the chains and pads are referred to as undercarriage. And every part has wear against everything else. About the only part that doesn't wear are the track frames, but they can be torqued and bent during use and so have their own repair needs.

Wear and repair that doesn't cross back to wheel tractors. Oh, and the steering clutches as well. It all can keep one busy.

Stan

[Lavoy]

If you are out of adjustment, then your pins and bushing are worn out and out of pitch. Out of pitch tracks force the sprocket to wear to match them. So you are accelerating the wear on the sprockets and sooner or later the bushings will perforate, and it is not cost effective to rebush your old rails, if I can even get pins and bushings any more. So if you knock a link out or space out the front idler to keep running worn out chains, you do so knowing that you are not concerned about adverse wear on the sprockets, and eventual perforation of the bushings, meaning they are "destroyed" if that makes sense.
Lavoy

[Kolot]

Explained it makes perfect sense, and the only solution to this is new chain thats understood. In the scope of things sprockets are not that much so think I will drop a link to get that adjuster back in the bore, it's new and I dont want all that rod exposed to all the elements , rocks and things. If it runs well and does what it is supposed to, I don't see a problem with new chains down the line. Like I said, I just got this and have never worked it. Any problem with the master pin going back in if I take a link out. Don't know if the master pin is used in a different master link if you will, or are all links in the chain the same. Seems to me they had a different part number for different links but that may have been headed master pin vs. headless pin, sound right?

[Lavoy]

Rails are the links, pads is what bolts to the rails, and engages the ground.
Lavoy