Upper Roller Bearings and Tracks Falling Off?

[Mark A Weiss]

Since I got my new tracks a couple years ago (they are somewhat longer, so the adjuster is 5" further extended), I've been having issues with tracks coming off the sprockets frequently.

I called my diesel mechanic (same guy who fixed my hydraulic line under the cabin in March) and he pointed out two things:

Tracks too tight
Upper roller bearings completely gone

I originally called him to adjust the big nuts that set the depth of adjustment for the track adjusters, but he's convinced it's these upper bearings. The roller sags about 2° as a result on both left and right tracks. He said that's guiding the tracks off the sprockets.

My original understanding was that the big springs that surround the pistons that comprise the track adjusters were what keep the tracks under tension, but he said that's incorrect that they are only there as shock absorbers.

So I've got a pair of these rollers on order now.






What do you guys think about the effects of this roller being off kilter? Is the mechanic correct about this?

 

[Nige]

he said that's incorrect that they are only there as shock absorbers.

He is correct. the hydraulic cylinder maintains the tension, the big spring is there for shock loads when you get something stuck in the track.

Since I got my new tracks a couple years ago (they are somewhat longer, so the adjuster is 5" further extended), I've been having issues with tracks coming off the sprockets frequently.

There's your problem right there. The tracks are too long and the hydraulic adjuster is over-extended.

 

[Mark A Weiss]

He is correct. the hydraulic cylinder maintains the tension, the big spring is there for shock loads when you get something stuck in the track.

There's your problem right there. The tracks are too long and the hydraulic adjuster is over-extended.

Well that was my thought, but the mechanic said that's not the problem. He in fact told me the tracks were over tightened. And he showed me where they are beginning to show cracks in the rubber from over stretch. (my original reason for calling him was to adjust the nuts that set the depth of the pistons.)

But what do you think about the upper rollers causing the track to be guided to one side and eventually off the sprocket?

 

[Tones]

Are the tracks coming off when reversing ( sprocket leading) or both directions?
Has the bolt that goes through the spring been checked? If that is broken it will cause (a) the tracks to look tight and (b) the tracks to flop off the sprockets.

 

[Mark A Weiss]

I don't recall if it was just on reverse. I do know that sometimes if I drive over a rock the affected track may come off. The last time the left track came off, I was driving straight backwards though. I suspect I've had tracks come off while driving forward as well.

 

[Tones]

Next time the track comes off pull the idler out, the spring should come with it. Then check the gap in the spring coils or see if the bolt moves. These bolts breaking isn't unusual, had one go on a new Cat 320 with 70hrs on the meter.

 

[Welder Dave]

The carrier roller looks pretty worn out but I don't know the original diameter. Being that the track has been wearing the mounting bracket, I would guess the rollers original diameter to be 2" or so bigger. It's not a lot but would still make the track tighter without using as much of the adjuster travel. If the bearings are shot could make the track go out of line.

 

[Vetech63]

Have the idlers been checked?

 

[92U 3406]

That carrier roller is done. Looks worn out and the bearings look like they're gone.

What's the idler look like?

 

[Mark A Weiss]

The idlers look fine. The mechanic also told me it looks like the previous owner had done a partial undercarriage rebuild, as the rollers on the bottom side all are in good condition.

I'm not sure what bolt is in the track adjuster that I need to look at. The track as to be completely removed to get at that, which is a LOT of work without a second machine to do the lifting.

 

[Tones]

It's the bolt that goes through the spring from 1 end to the other.
With a little bit of ingenuity your machine can pull out the ldler and stuff it back in.

 

[Mark A Weiss]

I know it can be done, and I did it when I had to replace a stuck adjuster and the track was completely off the machine. But that was an all day process and a lot of physical labor. Add in a recent heart attack and I'm not doing anything that physical for a while.

 

[Tones]

Fair enough.