Broke my shaft!

[yoteantidote]

Calm down I’m talking about my tractor[emoji16]
I’ve had my tractor for a few years but today is the first time I have EVER used my pto. My friend gave me a 5’ brush hog and I decided to test it out today.

I brushed hogged for quite some time then just about when I was done I hit a rock that stalled my tractor (L3901). The tractor started right back up again but when I engaged the pto I heard something wrong. Immediately I pressed in the clutch, disengaged the pto and took a look behind me. That’s when I noticed the shaft was not connected, I went to reconnect it and noticed the outer shaft is cracked down two sides. I did nothing other than hook the up, meaning I never measured the length of my pto (didn’t know that you should until it was to late) but I don’t want this to happen again so I want to make sure of the cause.

I’m guessing the shaft that broke was way to short and that’s why it separated but only cracked the one shaft versus blowing it apart, second it doesn’t appear that the shaft has any slip or shear pin saftey in it.

Anybody with more experience that could explain what happened and how to prevent it from happening again.

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[Daren Todd]

Glad you specified in the beginning

Looks like it snapped when contacting the rock. With it being short, and pressure from the sudden stop. Installing a slip clutch or shear pin would definitely save another shaft.

Coworker had a similar issue with his father in laws tractor. He showed up to work one day with a PTO shaft that was spun about 6 revolutions. Looked like an ornamental railing

He hit something solid without a slip clutch or shear pin. It twisted the shaft. Bought a new pto shaft, never checked the length. The new one was two long, and ended up busting the U-joints out of it. He had it up to the shop, told me what happened. First question I asked is if he checked the length to make sure it wasn't binding.

Had him bring the tractor, brush hog, and a new pto shaft up to the shop. Where I showed him how to check length and to cut it down to the right size.

 

[russell.still.5]

Looks to me like the shaft was under sized for the implement. You have a shear bolt at the gear box. Sometimes I have seen people put grade 5 or even grade 8 bolts as shear pins. A shear pin should never be over a grade 2. Also ch co and make sure the pto shaft isn’t seized onto the gearbox shaft. That had happened to me with an auger. 100hp tractor made a pretty twist pattern out of the shaft before it finally gave up.


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[mcfarmall]

When you remove the shear bolt at the gearbox to check for seizure, make sure the snap ring is in place on the gearbox input shaft. It keeps the yoke from sliding off the gearbox shaft when the shear bolt fails preventing it from whipping around and causing damage. As Russell says, for a 5' cutter it probably is only a 40hp gearbox and you should be using a Grade 2 bolt as your overload protection.

 

[yoteantidote]

Thanks guys, I will just replace that bolt regardless. Nothing is seized I can still spin the gear box shaft by hand. Pretty bummed cuz I was actually having a lot of fun[emoji1]


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[D2Cat]

Check to see what Mcfarmall has mentioned. There is a groove at the very end of the gear box shaft and is there to hole a snap ring. As he said, when the sheer bolt breaks that snap ring keeps the yoke on the gear box out put shaft. If the snap ring is neglected and the U joint come off the shaft and rotating at 540 RPM you'll hear a even bigger racket, and more cost.

 

[Russell King]

And Captain Safety says you need a safety shield over the PTO shaft to keep your arms and legs safer!


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[Dave_eng]

That square tube style of shaft is notorious for being slid together out of phase resulting in severe vibration.

The original design had a ball bearing pressed into a hole on the inner shaft but it was often cut off when adjusting the shaft length and the indexing feature lost.

I am also inclined to think the shaft parts of your pto are home made when I see the wall thickness of the failed tube. A five foot bush hog stores a lot of rotating energy. On some tractors, likely not yours, the pto shaft on the tractor does not have an overrunning clutch feature and the rotating bush hog will force your tractor forward even though you are trying to stop

You risk serious & very expensive damage to your tractor using a shaft like that. Worse, using the shaft without a proper shield is foolish. If you have a family, you are not considering what a serious injury to you will have on them.

Your free bush hog could cost you serious $ in internal transmission repairs.

A shaft like that can flail around like a medieval weapon of war.

Invest less than $300 to get a high quality pto shaft from a dealer who will set it up for your tractor. Not knowing about the critical implications of a too long shaft has destroyed the rear casting on many a tractor.

You need to be shown by someone with knowledge not learning on the job as the tales of operators with ripped off legs or worse are everywhere.

https://www.youtube.com/results?search_query=pto+shaft+amputates+leg

https://www.youtube.com/watch?v=EBSwOS90wgQ

I am sorry if I am sounding overly critical of you but the seriousness of the situation, for your future benefit, makes it necessary.

My comments are meant to get you refocused on the dangers from tractor operation not to put you down..
Dave

 

[yoteantidote]

That square tube style of shaft is notorious for being slid together out of phase resulting in severe vibration.

The original design had a ball bearing pressed into a hole on the inner shaft but it was often cut off when adjusting the shaft length and the indexing feature lost.

I am also inclined to think the shaft parts of your pto are home made when I see the wall thickness of the failed tube. A five foot bush hog stores a lot of rotating energy. On some tractors, likely not yours, the pto shaft on the tractor does not have an overrunning clutch feature and the rotating bush hog will force your tractor forward even though you are trying to stop

You risk serious & very expensive damage to your tractor using a shaft like that. Worse, using the shaft without a proper shield is foolish. If you have a family, you are not considering what a serious injury to you will have on them.

Your free bush hog could cost you serious $ in internal transmission repairs.

A shaft like that can flail around like a medieval weapon of war.

Invest less than $300 to get a high quality pto shaft from a dealer who will set it up for your tractor. Not knowing about the critical implications of a too long shaft has destroyed the rear casting on many a tractor.

You need to be shown by someone with knowledge not learning on the job as the tales of operators with ripped off legs or worse are everywhere.

https://www.youtube.com/results?search_query=pto+shaft+amputates+leg

https://www.youtube.com/watch?v=EBSwOS90wgQ

I am sorry if I am sounding overly critical of you but the seriousness of the situation, for your future benefit, makes it necessary.

My comments are meant to get you refocused on the dangers from tractor operation not to put you down..
Dave

Dave,

I don’t feel offended at all, just the opposite in fact. I’m going to take your advise and take the tractor and brush hog up to the dealer and get a new pto shaft. Without knowing much about pto equipment I would probably buy the wrong thing if I went without it.

I appreciate all the information from everyone!


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[Dave_eng]

Dave,

I don’t feel offended at all, just the opposite in fact.

I am relieved you did not take offense and instead are seeking qualified help.

Plse look closely at these two photos of the ends of your old pto shaft.
The way the retaining clips hold the U joint bearing cups in place are completely different.

This joint difference + the thin walled outer shaft are what lead me to conclude this was a jury rigged dangerous shaft

Dave

 

[adventure bob]

Both clip methods of bearing cap retention are valid, nothing nefarious or redneck here. Style is simply based on the ears of the joint. You can buy joint in either style for nearly any u joint. I just looked at Spicers website and they even offer a u joint with 2 outer and 2 inner clips.

 

[Tx Jim]

OP's square shaft appears to be twisted if so it needs to be replaced. With sq shaft twisted there's no way the u-joints can be phased(timed) correctly.

 

[Dave_eng]

Both clip methods of bearing cap retention are valid, nothing nefarious or redneck here. Style is simply based on the ears of the joint. You can buy joint in either style for nearly any u joint. I just looked at Spicers website and they even offer a u joint with 2 outer and 2 inner clips.

I have never seen one ag. pto shaft have different bearing cup retainers on each end of one shaft. I agree both designs are valid.

If you can point me to a COMER or other ag pto shaft where the joint retention styles are different on each end, it would expand my knowledge to see this.

Looking forward to what you can show me
Dave

 

[adventure bob]

Dave, I don't mean to imply it was stock. It looks, judging by the weld at the broken end that a new yoke was installed on that shaft at some point in time. My goal was to prevent is someone walking away with an idea that internal or external bearing retainer clips or disparate yoke types from end to end is relevant to the issue.

I think (restatement for understanding) that your point is that because they don't match someone monkeyed with it. (?)

A possible alternative is that someone broke an ear off the yoke in a previous incident and welded a new one on with considering the other damage to the shaft.

 

[North Idaho Wolfman]

A possible alternative is that someone broke an ear off the yoke in a previous incident and welded a new one on with considering the other damage to the shaft.

It's also possible that they welded it on in the wrong clock position too.

I think we have all concluded, throw that one in the trash bin and get a new one, with a guard!

 

[Dave_eng]

Dave, I don't mean to imply it was stock. It looks, judging by the weld at the broken end that a new yoke was installed on that shaft at some point in time. My goal was to prevent is someone walking away with an idea that internal or external bearing retainer clips or disparate yoke types from end to end is relevant to the issue.

I think (restatement for understanding) that your point is that because they don't match someone monkeyed with it. (?)

A possible alternative is that someone broke an ear off the yoke in a previous incident and welded a new one on with considering the other damage to the shaft.

Thank you for clarifying what you meant. My point, poorly expressed, was because it looked modified, it is possible it never was properly indexed.

Dave