Here we go again 140M DOWN

[ovrszd]

Do you happen to know how many hours were on the original chains when they were replaced.?
Is the machine Serial Number below B9D01578, B9G00158, B9M00596, or D9G00115.?
Did Cat also replace all the sprockets when they replaced the chains under warranty.?
How many operating hours on the replacement chains.?
Also do you have any photos of the broken link taken from the side as opposed to from the end as per the photo above.? I need to see the shape of the side plates (this might be important).
Also are there any identifying marks stamped on the link side plates.?

Good post. Hope we get some answers to those questions, not to cast blame, just to educate ourselves.

 

[20/80]

Do you happen to know how many hours were on the original chains when they were replaced.?
Is the machine Serial Number below B9D01578, B9G00158, B9M00596, or D9G00115.?
Did Cat also replace all the sprockets when they replaced the chains under warranty.?
How many operating hours on the replacement chains.?
Also do you have any photos of the broken link taken from the side as opposed to from the end as per the photo above.? I need to see the shape of the side plates (this might be important).
Also are there any identifying marks stamped on the link side plates.?

If I remember right there was 4000hrs on the first chains, and I don't think they replaced the sprockets, there's about 8000hrs on the replacement chains, I was looking for the broken side link today, couldn't find it, our mobile must have it, Cat was wondering if it was the master link that let go, it was not. i will check with the mobile also see if there is any markings and snap another picture.

 

[Nige]

Cat was wondering if it was the master link that let go, it was not. i will check with the mobile also see if there is any markings and snap another picture.

Any more pictures of the chain around the area where it broke,especially taken from the side, would be useful.

Any definite info you can get hold of regarding if the sprockets were replaced or not would be good.
The way I see it is if the rollers on the first set of chains broke up that would lead to the pins connecting the links riding on the sprockets instead of the rollers. This would create some very high contact pressures and I'm sure would have marked the sprockets. For that reason alone it would have been prudent for the dealer to replace the sprockets under warranty and claim them as "contingent damage" from the mode of chain failure. Whether that has anything to do with the second failure or the current condition of the sprockets I can't state for sure because I'm not standing there looking at them.

 

[20/80]

Any more pictures of the chain around the area where it broke,especially taken from the side, would be useful.

Any definite info you can get hold of regarding if the sprockets were replaced or not would be good.
The way I see it is if the rollers on the first set of chains broke up that would lead to the pins connecting the links riding on the sprockets instead of the rollers. This would create some very high contact pressures and I'm sure would have marked the sprockets. For that reason alone it would have been prudent for the dealer to replace the sprockets under warranty and claim them as "contingent damage" from the mode of chain failure. Whether that has anything to do with the second failure or the current condition of the sprockets I can't state for sure because I'm not standing there looking at them.

I asked our mobile this morning that did the work about the first set of chains that were damaged, he said Cat just sent them the new chains, the drive sprockets were not wore enough to justify replacing according to Cat, while all along the machine was under warranty we did the work and replaced the chains not Cat, I will try to get some more pics for you of the recent breakage of the chain and side link that let go.

 

[20/80]

Here are some more pics Nige

 

[Nige]

Did someone take a gas axe to that chain to get it out.? Sure looks like it was gas-cut.

That's an old-style chain with the side plates shaped like an 8. New ones look like the image below with parallel side plates.
I'll bet good money that the crack was started when the rollers of the original chains fell apart. The pins would have been running right in the root of the tooth and the point loads would've been off the scale.

 

[DB2]

What size are those chains ?

 

[Nige]

What size are those chains ?

2¼" pitch on this machine. 2½" pitch on a 16, 3" pitch on a 24.

 

[20/80]

Did someone take a gas axe to that chain to get it out.? Sure looks like it was gas-cut.

That's an old-style chain with the side plates shaped like an 8. New ones look like the image below with parallel side plates.
I'll bet good money that the crack was started when the rollers of the original chains fell apart. The pins would have been running right in the root of the tooth and the point loads would've been off the scale.

View attachment 257279

Yeah they were cut, only way our mobile could get the chain out of the housing, the chain was tightly jammed up in the final drives, should the newer style chain have been in this 2008 140m? just thinking with the introduction of the M series they would not be mix and matching with the old design.

 

[Vetech63]

while all along the machine was under warranty we did the work and replaced the chains not Cat,

Why?

 

[20/80]

Why?

Not sure, but will find out, you would think while under warranty Cat would do the work.

 

[Nige]

should the newer style chain have been in this 2008 140m?

To the best of my knowledge they should have been installed when the warranty repair was done @ c4K hours. They would not have been original fitment at time of machine build, they came later.

I still am of the opinion that because of the mode of the initial chain failure the start of the sprocket failure process occurred at the same time. The external cracks in the photos would appear later, it’s known as high-cycle fatigue. What happens is that higher than normal stresses (chain roller collapse in this case) initiate some sort of internal defect. Normal operating stresses after that time (with the new chains in place) would slowly develop the defect into a full-blown crack and to the eventual failure of the sprocket. In this case though, the chain failed first although it’s obvious from the photos that the sprocket was not far behind it.

I hope that explanation makes some sort of sense.

Question: This is all on one side of the machine. I hope someone is going to take a very close look at the other side...?

 

[Nige]

Not sure, but will find out, you would think while under warranty Cat would do the work.

Sometimes it's nothing more than convenience. Dealer doesn't have the necessary resources immediately available but the parts are on site. Customer wants the machine back to work PDQ so does the work and in the process accrues Brownie Points for the next time they need a favour from the dealer.

 

[Welder Dave]

Had to be some kind of stress to crack in the sprocket root! Why weren't the sprockets replaced? Cat should be doing the labour and replacing everything now. What a nightmare of a machine.

 

[20/80]

To the best of my knowledge they should have been installed when the warranty repair was done @ c4K hours. They would not have been original fitment at time of machine build, they came later.

I still am of the opinion that because of the mode of the initial chain failure the start of the sprocket failure process occurred at the same time. The external cracks in the photos would appear later, it’s known as high-cycle fatigue. What happens is that higher than normal stresses (chain roller collapse in this case) initiate some sort of internal defect. Normal operating stresses after that time (with the new chains in place) would slowly develop the defect into a full-blown crack and to the eventual failure of the sprocket. In this case though, the chain failed first although it’s obvious from the photos that the sprocket was not far behind it.

I hope that explanation makes some sort of sense.

Question: This is all on one side of the machine. I hope someone is going to take a very close look at the other side...?

Yes thank you Nige, I have suggested that they better have a close look at the other side before it fails also, but the department will just ignore the request, someone in upper management that thinks they know better does not want to spend the money in wages for the mobile to pull the other side apart, bean counters that can't count, lol, would be a perfect time do do so while waiting for the parts for the other side, 4 weeks now.

 

[20/80]

Had to be some kind of stress to crack in the sprocket root! Why weren't the sprockets replaced? Cat should be doing the labour and replacing everything now. What a nightmare of a machine.

Yes this machine has had alot of problems from day one, I don't think Cat would want to use this machine they made as a advertisement for selling the M series graders, lol, but I hope this post helps buyers ask questions when looking at a used or new M series grader

 

[Nige]

Yes thank you Nige, I have suggested that they better have a close look at the other side before it fails also, but the department will just ignore the request, someone in upper management that thinks they know better does not want to spend the money in wages for the mobile to pull the other side apart, bean counters that can't count, lol, would be a perfect time do do so while waiting for the parts for the other side, 4 weeks now.

I think it could all be done without disassembly, simply drain the oil from the tandem and let everything sit and drip for 24 hours or so.
The sprockets could be inspected pretty easy with a borescope, or even a GoPro on the end of a selfie stick. Same for the chains that could be inspected through the rectangular holes in the top of the tandem case and simply rotate the wheels through one full chain circuit. Where there's a will there's always a way. Where there isn't a will - well you know where that all ends up............

 

[20/80]

I think it could all be done without disassembly, simply drain the oil from the tandem and let everything sit and drip for 24 hours or so.
The sprockets could be inspected pretty easy with a borescope, or even a GoPro on the end of a selfie stick. Same for the chains that could be inspected through the rectangular holes in the top of the tandem case and simply rotate the wheels through one full chain circuit. Where there's a will there's always a way. Where there isn't a will - well you know where that all ends up............

Yes I agree Nige, maybe it will happen hopefully, grading season is here, we need the machine.

 

[ovrszd]

This is another example of the excellent knowledge and support we all get from NIGE on this site. He's invaluable and I've learned a LOT from reading his posts. I hope he outlives me. Thanks NIGE!!!!