Cat 953a under carriage rubbing questions?

[Georgia Iron]

I extended my idler arm with grease. Now the yoke is rubbing on the wheel. Is there another adjustment or is my chrome idler shaft broken since it is leaning down?

Are there any alternative repairs for this?

 

[Nige]

At a first glance I'd say that the pins & bushes in the tracks are so worn the adjuster has over-extended. Others may have differing opinions.

 

[Georgia Iron]

Well, the tracks seemed to tighten up nice but when I attempted to back up my shaft spilt.



So it's almost broke in half and I need this machine to load on a trailer and unload at my shop so I can figure out how to fix this.



I am thinking I need to attempt to weld the top of the break to limp it on the trailer. Any idea why the yoke touched is this a normal problem with these older machines? Trying to understand what why and how, I messed this up?

Everything was working great till I tightened it up with grease.

 

[Dickjr.]

I've seen this before on a 53B , which is different but work the same. The chrome rod has been extended out of the rear bushing and that lets it lean down. Also the yoke shouldn't touch the idler. It looks , which it needs to be measured , like the rails are pretty well shot. I don't know the measurement but you can measure across four pins and it will tell you how much wear you have. The positive , the pads look good , and if the rollers are good you can do a pad swap to new rails , new segments and rock on. About 3000 would catch it. I am currently putting a new set of rails , pads and segments on my 943. Also front idlers. I will post some pics here if you don't mind. Also I can direct you to a place to get the parts if you need.

 

[Cmark]

I think it's possible that your idler bearing has collapsed allowing the idler to move backwards, grab the yoke and drag it downwards when you reversed.

 

[Scrub Puller]

Yair . . .

Ignorance speaking. Does that chrome pushrod have a ball end to allow for misalignment as the pivot moves forward from new rails worn out rails?

Like Cmark I thought about the collapsed bearing/broken shaft scenario but no sign of any oil?

Cheers.

 

[Cmark]

The yoke pivots at the rod end and also at the fork end to maintain alignment. The rod runs in a bush at the track frame end so it's either broken or come out.

When an idler gets to the stage where the tread is rubbing on the yoke, the oil is usually long gone.

 

[Scrub Puller]

Yair . . .

Gotcha Cmark. Perfectly obvious in first pic. (thumps head)

Cheers.

 

[ship660]

You need to move the rock guards forward. there is another set of bolt holes in the track frame. unbolt it and move it until the edge of guard is flush with the track frame. Doing that will give you around another 1000 hours.

 

[lantraxco]

You need to move the rock guards forward. there is another set of bolt holes in the track frame. unbolt it and move it until the edge of guard is flush with the track frame. Doing that will give you around another 1000 hours.

This^^

 

[Dickjr.]

It looks like it has already been moved ahead. If the op can remove the cap on the adjuster valve and see if the block is close to the frame casting it has been moved. With the rob being pushed out so far it would lead me to believe its out of travel on the adjuster. Usually there is about 3 to 4 inches from the front of the rock guard to the end of the roller frame to allow the idler to be moved. I may be dead wrong , who knows.

 

[lantraxco]

Looks like it's butted to the roller at the back, should be one or two bolt holes forward still I think.

 

[Dickjr.]

lantraxco , I see that now. If the idler is moved ahead , does the swing arms lay back so the adjuster works properly? I am currently putting all this on my 943 , With new rail and idlers I would start with the idler butted like this one is? I'll get some pics , but I got all the good and then some out of my u/c. The bushings were flaking and the segments had worn to the drive hub. Didn't get into it . Georgia Iron , the chrome rod should push back in against the tensioner if its like mine.

 

[Heavey Metal]

How is moving the rock guard going to fix the bad bearing?

 

[ship660]

He didnt say anything about a bad bearing. Just said yolk was rubbing against idler and track adjust was fully extended. Moving guard forward changes the lower mount for idler giving you about 4-8 inches of adjustment on track tensioner.

 

[lantraxco]

How is moving the rock guard going to fix the bad bearing?

The round thing in the middle of the rock guard is the lower pivot for the idler, idler doesn't slide like a dozer, it's on the end of an arm that pivots. As you move the lower pivot forward, it moves the yoke backward, allowing for more adjustment, as ship660 said.

 

[Scrub Puller]

Yair . . .

So what is the design philosophy behind the pivoting rather than sliding idler?

Cheers.

 

[lantraxco]

Yair . . .

So what is the design philosophy behind the pivoting rather than sliding idler?

Cheers.

Darned if I know, I always figured Drott or somebody built one that way so everybody else did too?

It might be because of the front idler always taking a beating on a loader as opposed to the dozers, maybe the pivot deal reacts faster and with less wear than the sliding setup? Also I suppose the idler travels in a sort of arc when it hits a hummock so it has a little bit of suspension travel?

 

[Dickjr.]

I'm still in a learning curve so to speak, but it looks like the way the rock guard bolts on and pivots is designed to hold the added weight of the loader. I know my dozer , the idler kind of floats up and down a little when working. We had Case dozers , and they had rubber springs that went between the top of the roller frame and idler mount. Looking closer , its really a pretty good set up as far as being solid and taking the weight , still allowing the adjustment of the rails. I have been around 955 ,but never paid any attention to how they were put together.

 

[Scrub Puller]

Yair . . .

Gotcha fellers, I figured it had something to do with extra weight of the loaded bucket and constant digging.

I have had little to do with diggers but I think Allis used the conventional system with their crawler loaders . . . some of the Allis's and Cat's had a high and low position for the idler . . . low position for blade work and high for agricultural and scooping.

Cheers.