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Discussion Starter #1
Hello,

We have had a reoccurring issue on an otherwise healthy 9600 combine. The cooling shaft that connects to the engine via a harmonic coupler keeps failing right against the coupler itself. The welded bolt flange keeps breaking in the same place each time. The engine runs fine without any noticeable vibration or sound at all rpms. The rest of the cooling assembly seems fine. Bearings are smooth and tight. Assembly can be turned by fingers alone in a smooth and quiet manner. The screen cleaner is also smooth and quiet. It appears for this to break in this location there must be some sort of flexing going on that currently isn't noticeable. Two things are lightly mentioned online but don't seem to apply to this after review. 1. That the outer engine bearing is starting to go and this vibration is failing the connection, or 2. that the engine itself has settled into the frame and when on high torque load specifically, tilts ever so lightly but enough to fail this joint.
Does anyone have any other ideas? Would greatly appreciate any other ideas or insights that we have not identified so far. Or, even if you have had the same failures and how you isolated the cause and resolved it.

Its an expensive part an it takes the best part of an hour to replace this with another failure coming within the same round on the field. So very stressful and confusing at the same time.

Any help is very much appreciated.

Regards.
 

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I have no idea about this equipment but it sounds like a rotating shaft, maybe driven by another shaft since it is bolted together with a flange. You say it turns easily by hand in a smooth and quiet manner---it never comes to any point in its rotation where it gets even slightly harder to turn? Can you use a straightedge or something to check alignment with whatever drives it? If there's no vibration or anything, maybe you got into a batch of defective parts?:dunno:
I'll look it up on JD parts and see if I can figure out what you're dealing with
 

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Torque load

Hello,

We have had a reoccurring issue on an otherwise healthy 9600 combine. The cooling shaft that connects to the engine via a harmonic coupler keeps failing right against the coupler itself. The welded bolt flange keeps breaking in the same place each time. The engine runs fine without any noticeable vibration or sound at all rpms. The rest of the cooling assembly seems fine. Bearings are smooth and tight. Assembly can be turned by fingers alone in a smooth and quiet manner. The screen cleaner is also smooth and quiet. It appears for this to break in this location there must be some sort of flexing going on that currently isn't noticeable. Two things are lightly mentioned online but don't seem to apply to this after review. 1. That the outer engine bearing is starting to go and this vibration is failing the connection, or 2. that the engine itself has settled into the frame and when on high torque load specifically, tilts ever so lightly but enough to fail this joint.
Does anyone have any other ideas? Would greatly appreciate any other ideas or insights that we have not identified so far. Or, even if you have had the same failures and how you isolated the cause and resolved it.

Its an expensive part an it takes the best part of an hour to replace this with another failure coming within the same round on the field. So very stressful and confusing at the same time.

Any help is very much appreciated.

Regards.
That's a tough one. I don't think I've even looked at the engine on a 9600 but do agree that a shift in the engine under load is a possibility. If that's a solid coupling, it really wouldn't take much movement to break it. Since it is a recent issue and repeats, I would guess it's somehow age related. The engine mounts would be a possibility as would a bearing. Unfortunately, checking out either of those will be difficult, particularly if it's an engine load related issue. Maybe some of the JD guru's have some experience.

Treefarmer
 

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Discussion Starter #4
I have no idea about this equipment but it sounds like a rotating shaft, maybe driven by another shaft since it is bolted together with a flange. You say it turns easily by hand in a smooth and quiet manner---it never comes to any point in its rotation where it gets even slightly harder to turn? Can you use a straightedge or something to check alignment with whatever drives it? If there's no vibration or anything, maybe you got into a batch of defective parts?:dunno:
I'll look it up on JD parts and see if I can figure out what you're dealing with

Hello,
Thanks for the input. yes - it turns easy threw a lot of turning by fingers. No adjusting of resistance and no uneven support or shifting. Belts are perfectly aligned by straightedge. Shaft that keeps breaking is perfectly straight before and after failure. We are thinking we will put a dial indicator on the engine pulley itself to see if we can detect some shifting or torqueing over somehow. We will continue to see if we can get this sorted out. We have two other combines running but having the third running would sure help now that we are more than a month late in harvest so far. If you think of anything else, please drop me a line here and we will see what can be found. This problem has a number of people confused so maybe this is something unique to this machine? I hope not.
Cheers
 

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HP8022_________UN12NOV98.jpg

Is this what you're dealing with?

If so then could the end of the crankshaft be bent causing the harmonic balancer pully to wobble? What about the driven pully on the opposite end of the shaft? I'm thinking that with the belts installed and tight, any pulley wobble would alternately tighten/loosen the belts as the assemby rotates and cause vibrations which I guess could break the flange (12) attached to the crankshaft.
 

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Tough one is right but I think you're on the right path with a dial indicator. It would be nice if you could mount the indicator to the shaft and sweep the face of #22 (machined surface). Something's certainly out of alignment. The joint being either open or closed at the top.
From here I'd be more suspicious of the support at the other end of the shaft more so than the engine (driver side) of the coupler.
 
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