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Discussion Starter · #1 ·
I just started baling Saturday, about 15 bales into the field or so, and my PTO yoke at the slip clutch on the flywheel broke in half. The shaft does not appear to be twisted, so it would only need a new yoke welded on, and the u joint on the flywheel yoke was still fine (except for the bearings that go in to the broken yoke).

I did not notice if the shear bolt on the flywheel was broken or not; I need to check that.

Took it into the driveline shop to get it fixed up quick today and they said there was no way a bad u joint could have caused this.

My concern is when something breaks, I want to understand why it broke. If it couldn't be caused by the u joint (which was greased fairly regularly albeit not as regularly as it probably should be since a shield has to be removed in order to get to it).

Last year I hit a tedder tine arm with the plunger. This broke a shear bolt but I've baled thousands of bales since then. The last time this baler was used before this was a week ago and baled 1200 bales that day. I baled 700 then another area hay farmer used it to bale 500 bales right afterwards when his baler was having issues. This was the first time I've used it since then and it does this 15 bales in.

Looking for ideas for what could have caused that PTO yoke to just crack in half like that and anything else I should check. Clutch appears to be fine. I didn't hit anything in the field. I still need to turn the baler by hand. I just don't want to break a second yoke by not isolating the issue.
 

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Did you look at the yoke to see if we're it cracked was all new metal and didn't have any old exposed part? Hard to explain but I've had stuff break like that and you can tell front the break that it had a small crack in it before the rest broke. One would be shiny and clean and the other is dull.
 

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The ujoint is a common joint, the yoke on the other hand may not be. What you have to look for is how the rectangular hole that slides on the shaft is positioned in comparison to the ears of the yoke. Are the ears of the yoke in line with the wide part of the rectangle or are the ears in line with the narrow part of the rectangle. The common yoke you can find may be 90 degrees off from what the baler has on it. This will throw the pto out of phase and cause vibrations issues and knocking
 

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Discussion Starter · #8 ·
Check the flywheel shearbolt is correct, and correctly tightened. Also check the plunger knives and make sure they cannot lock together.

Roger
I had just checked those tonight. It’s a new shearbolt and shearbolt was intact. I could rotate plunger freely.
 

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Discussion Starter · #9 ·
Here’s a question for y’all—could turning too sharp do this?

reason I ask is the other farmer who used it after me made a really sharp turn with about 4 bales left. It was so sharp he bent the tongue of my wagon and is now fixing it.

The next person to use baler was me, and 15 bales into it it breaks. So that makes me really suspicious that he might have cracked it, especially since the turn happened right at the end of his session and the break happened right at the beginning of mine.
 
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Are you sure that section of the pto shaft slides when you turn? From my past days of using an offset baler, I seem to recall the section between the flywheel and the front post only moves when you adjust the tongue position. Wouldn't it be the short shaft from the post to the tractor pto that could get bound up if you turned to sharply?

I am thinking high cycle/low amplitude fatigue failure. A small crack starts and propagates until there is not enough material to handle the load.

When was the last time you burnished the slip clutch? Could you have been subjecting the yoke to a small shock with each plunger stroke due to a frozen slip clutch?
 

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Here’s a question for y’all—could turning too sharp do this?

reason I ask is the other farmer who used it after me made a really sharp turn with about 4 bales left. It was so sharp he bent the tongue of my wagon and is now fixing it.

The next person to use baler was me, and 15 bales into it it breaks. So that makes me really suspicious that he might have cracked it, especially since the turn happened right at the end of his session and the break happened right at the beginning of mine.
I have in haste turned sharp enough to bend a wagon tongue and that still doesn’t stress the baler that much. I can’t imagine someone did it turning sharply. While I don’t disagree with the premise of wanting to know why it failed, I would chalk this up to fatigue and not think about it again.
 

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Discussion Starter · #13 ·
Are you sure that section of the pto shaft slides when you turn? From my past days of using an offset baler, I seem to recall the section between the flywheel and the front post only moves when you adjust the tongue position. Wouldn't it be the short shaft from the post to the tractor pto that could get bound up if you turned to sharply?

I am thinking high cycle/low amplitude fatigue failure. A small crack starts and propagates until there is not enough material to handle the load.

When was the last time you burnished the slip clutch? Could you have been subjecting the yoke to a small shock with each plunger stroke due to a frozen slip clutch?
I think you and the others are prob right. Initially I didn’t think that u joint saw much, if any, angle but I did notice the pedestal on the middle joint does swivel so then I doubted myself.

That slip clutch has not been burnished in…..a very long time. I was just looking at it tonight wondering if it even works. I need to get on that.
 

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Doesn't that baler have a smaller shaft section and center mount point at the hitch?
You should be able to find that yoke pretty easy, at least it is not the baler side! Them pieces is $$$ ...
 

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Many years ago when we still ran a JD 328 little square, we had several failures of the last PTO yokes right in front of the baler. Apparently the yokes weren’t timed correctly and hammered themselves to death. Once that was corrected the PTO never failed again. This problem may not be possible on your machine depending on the design of the shafts but worth checking.
 

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Many years ago when we still ran a JD 328 little square, we had several failures of the last PTO yokes right in front of the baler. Apparently the yokes weren’t timed correctly and hammered themselves to death. Once that was corrected the PTO never failed again. This problem may not be possible on your machine depending on the design of the shafts but worth checking.
I've never read or heard where u-joint on JD small sq balers located just in front of slip clutch required timing with front telescoping shafts. IIRC when baler tongue is in field position that portion of driveshaft operates straight with baler tongue. Was your balers slip clutch operating as designed slipping minutely with every plungerhead stroke when hay was being feed into bale chamber??
 

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