TRACTOR SLUNG PTO SHAFT!!! - PICS.

[TexasDigger]

In case anyone takes life for granted when standing near a spinning PTO shaft - here's what can happen when a #8 grade bolt for PTO clutch is no match for PTO engagement at 2000 RPM's (that was my fault - had just turned PTO off and saw I had missed a spot so turned it right back on before before throttling down - clutch had already stopped all RPM's so when it re-engaged it hit HARD). This happened so fast that I didn't even have time to disengage PTO or kill the engine. Scared the living $#!#!#$ out of me and thank GOD I was out of harms way. Before I could even turn off key, shaft had already slung off the RC's gear-box, wildly flinging shrapnel into the abyss, slung around the strap metal holding weight for rear of RC, ripped the welded chain right in half and TWISTED THE ENTIRE STRAP FOR RC UP WITH PTO SHAFT!!! It instantly killed the engine from the shaft seizing due to being twisted up and can only hope no internal damage to engine/powertrain (sounded OK but will be keeping close eye on it). After further examination this morning, it also broke a U-joint and bent the U-join housing on yolk - was only a few revolutions away from slinging my clutch like a cannon-ball. Pics were taken this morning after I had already untwisted the PTO shaft and RC strap from one another - they were wrapped so tight that the best visual description I can come up with is that they were TWISTED AROUND EACH OTHER LIKE A BREAD TIE!!! They were twisted together so tight that I couldn't lower the 3 point down in order to to hook a chain to temporarily lift up the rear of mower long enough to get it back to house - had to un-twist them before I could move this mangled mess to further inspect the damage.

Lesson: Check all PTO u-joints & connections etc REGULARLY before operating. If you EVER suspect anything a-miss going on behind the back tires - ALWAYS disengage PTO. This could happen to anyone running a sheer-bolt style implement in a fraction of a second and if you get in the way of a spinning shaft or the debris flinging off of it while spinning at ANY RPM (In my case - 2000 rpm's = just <540), based on how quick it twisted up the 5/16-3/8? steel strap, it would be nothing for it to kill/severely mangle/dismember someone in its path. Scary stuff. Will always be more careful around PTO after seeing this & hope it helps anyone else that reads this to understand how serious that little scary sticker is about the PTO shaft's ability to cause physical harm/death. The little WARNING!/DANGER! sticker of the stick figure twisted up around PTO shaft is no joke - if you don't believe it, take a look at these pics & imagine that metal strap was your arm!

 

[ptsg]

Shouldn't there be a circlip that would prevent the shaft from coming off after the shear bolt broke?

I still don't understand how and why manufacturers insist on that design of shear pin with the smooth input shaft on the gearbox. Not only it makes it a mess to change the shear pin, it also makes it prone for this situation to happen.

Good thing there was no one around when that happened.

 

[TexasDigger]

No circlip or anything to hold in place - at least not that I could find. You would think they would come up with some kind of design where a spring-clip or something holds onto a groove to keep from sliding/spinning off (similar to the way the 6-spline end works). Something for mfr's to consider for the next Gen sheer-pin style! Just saw that there is a 6-spline shear pin set-up but doesn't help for implements with the standard 1 3/8 shaft where the shear bolt goes right through the shaft.

 

[ptsg]

No circlip or anything to hold in place - at least not that I could find. You would think they would come up with some kind of design where a spring-clip or something holds onto a groove to keep from sliding/spinning off (similar to the way the 6-spline end works). Something for mfr's to consider for the next Gen sheer-pin style!

I do see the groove on the shaft for the circlip. Either it was missing or it disappeared when that twisted mess happened which is unlikely as it would prevent that from happening in the first place.

There is no need for a next gen shear pin design. It's been around for years but US manufacturers just need to stop being cheap and simply use a standard 6 spline shaft on the input shaft of the PTO. When they do that, they also can use this style of shear pin showed on the image down below. It's easier to change the shear pin, no need to fight with a broken and stuck shear pin on the shaft and doesn't need to pull the PTO shaft out.

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[LS Tractor Owner]

Wow! That's some serious carnage. It sure took some force to twist the support!

Glad you didn't get hit with anything

 

[TexasDigger]

"I do see the groove on the shaft for the circlip. Either it was missing or it disappeared when that twisted mess happened which is unlikely as it would prevent that from happening in the first place.

There is no need for a next gen shear pin design. It's been around for years"

That 6 spline design is the one I was referring to - much nicer setup. Looking at the grooves on both the gear-box shaft and ALSO on my PTO clutch - neither the RC or the added clutch came with any type of a c-clip or a retainer clip.. didn't even know it was supposed to have one until you just posted & also just did a thorough Google search and couldn't find any mention taking off or re-installing a clip or anywhere to even buy one of these clips. Will definitely be installing these clips on both the shaft and my clutch after buying new shaft since there isn't much left worth repairing on this one!

Guess that the retainer clip's are supposed to be common knowledge? Anyone know what size clip this is - assuming it is probably a very common size (1 3/8"?)

 

[ruffdog]

The cutter had a clutch, not a shear bolt. The clutch didn't slip so the bolt was forced to shear. Maybe clutch models don't have the clip as shear pin models do because you would have to disassemble the clutch to install the clip. This is why we loosen the clutch to slip it every year.

 

[repete]

Well that clutch sure did not work...

 

[ljjhouser]

Great training pictures. Really glad that no one got hurt.

 

[TexasDigger]

Well that clutch sure did not work...

The cutter had a clutch, not a shear bolt. The clutch didn't slip so the bolt was forced to shear. Maybe clutch models don't have the clip as shear pin models do because you would have to disassemble the clutch to install the clip. This is why we loosen the clutch to slip it every year.

When the clutch was installed last year it came with a #8 grade bolt that replaced the #5 grade shear bolt. Clutch definitely didn't "clutch" at full operating speed! Sheered the #8 grade bolt so luckily it wasn't a high-quality American Made #8 grade bolt or it may have done even more damage to the gearbox/shaft. After repairing the RC & replacing the shaft, will definitely be slipping the clutch & checking adjustment (it's at the 1 year mark so is due).

Currently shopping for the retaining clips & getting a couple spares to make sure this never happens again with any other implements. Assuming since the shafts are 1 3/8" OD that the retaining ring/clip will be a smidge smaller. All I have near me is a TSC - looks like they stock 1 1/4 retaining clips so will put a micrometer on the groove to make sure that will work. Would have known to re-install these clips if they had ever originally been installed to begin with. Seems like anything that comes with a 1 3/8 sheer bolt through the shaft type set-up should automatically come with these clips for safety purposes... scratching my head on that one but at least wasn't hurt in the learning experience. Also have to find a straight piece of strap metal to fix this RC. That shouldn't be too difficult though.