TRACTOR SLUNG PTO SHAFT!!! - PICS.

[TexasDigger]

How do you get to the circlip with the clutch in place? The shaft sticking out of the clutch would block access to the circlip.

I will find out on reassembly - I assume the first half of clutch has to be installed, then clip, then re-assemble/adjust clutch, but will confirm once I get it back together.

 

[ROUSTABOUT]

Oh yeah it did! It sounded like machine-gun fire... even my wife came outside to check - she said the banging was so loud when it spun loose that she thought I had rolled the tractor over!

Mine flew off 3 times cutting hay a few days ago. Cutting 100 acres tomorrow. Maybe it'll do better. I tightened the trip on it.

 

[Tinhack]

I will find out on reassembly - I assume the first half of clutch has to be installed, then clip, then re-assemble/adjust clutch, but will confirm once I get it back together.

Yes, the clutch must be disassembled and reassembled on the shaft to install the clip. I took mine apart to clean the disks and clutch plate since they looked paint covered. And, oh yeah, I remember measuring the force to compress the springs 1/4". I don't recall any of them being the same or even the same free height. Off-shore stuff for sure. So instead of counting turns, as the instructions say, I used a torque wrench to match pressure against the plate once I got past the initial locknut torque. I wish I could remember the final torque since it took me a few trial and error attempts for my ~47hp PTO. At the time, I had some pretty high grass and weeds with some <2" saplings--Mostly Mesquite. I kept matching torque on the bolts until it didn't slip on "MY STUFF". I could hear the pitch change.

Oh, and my cutter is a six footer. Cheap Country Line so I added the clutch. YMMV.

 

[TexasDigger]

Yes, the clutch must be disassembled and reassembled on the shaft to install the clip. I took mine apart to clean the disks and clutch plate since they looked paint covered. And, oh yeah, I remember measuring the force to compress the springs 1/4". I don't recall any of them being the same or even the same free height. Off-shore stuff for sure. So instead of counting turns, as the instructions say, I used a torque wrench to match pressure against the plate once I got past the initial locknut torque. I wish I could remember the final torque since it took me a few trial and error attempts for my ~47hp PTO. At the time, I had some pretty high grass and weeds with some <2" saplings--Mostly Mesquite. I kept matching torque on the bolts until it didn't slip on "MY STUFF". I could hear the pitch change.

Oh, and my cutter is a six footer. Cheap Country Line so I added the clutch. YMMV.

Didn't think about torquing each nut individually - that would make sense (like a drum head!). I think I'm at 63 hp on the PTO which is a LOT for what I'm pulling behind it - still using my little medium duty six footer that came with my previous rig. Had no choice but to go with a clutch that obviously isn't clutching! Will get it figured out but looking like it may be this weekend before I have a free day to tinker.

 

[Sawyer Rob]

I've said it before on this site, and I'll repeat it here.

You have to adjust the clutch for the hp of YOUR tractor, not to some spec. in a book! That book doesn't know what YOUR tractors hp is.

SR

 

[LouNY]

Well I've just been reading and not commenting on this thread till now.
That thru bolt holding the slip clutch to the shaft is NOT a shear bolt. Yes, it sheared it is not intended to be the shear bolt or safety.
Unless a manufacture specifys a grade 2, 5 or 8 "shear" bolt I always use a grade 5 or an 8, they will shear clean and the pieces will be easier to remove. Grade 2 or ungraded bolts are likely to smear when they break making them selves harder to remove the pieces.
If the hole in the shaft is not the same size as the slip clutch and a snug fit it will be getting hammered back and forth every power cycle and will fail eventually.
Also if the threads of the bolt are in the plane of the shearing force the strength will be greatly reduced.
Also over tightening a shear bolt will change it's shear strength.

In my opinion the slip clutch should be adjusted to protect the implement,
if I have 80 HP on an implement that is rated for 40 HP the clutch needs to give when more then 40 HP is applied or when an obstacle is struck which results in more then the recommended power to keep rotating..

 

[kwbobwi]

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!

When I was on the farm, when ever we went to use a piece of equipment with a slip clutch we would loosened the clutch, engaged the pto to make sure it was slipping properly and then readjusted it, several times equipment that sat for a year or so the clutch would rust/seize together and be a pain to break loose.
The few extra minutes it takes to do that and check everything can save time and money down the road

 

[JWR]

Well I've just been reading and not commenting on this thread till now.
That thru bolt holding the slip clutch to the shaft is NOT a shear bolt. Yes, it sheared it is not intended to be the shear bolt or safety.
Unless a manufacture specifys a grade 2, 5 or 8 "shear" bolt I always use a grade 5 or an 8, they will shear clean and the pieces will be easier to remove. Grade 2 or ungraded bolts are likely to smear when they break making them selves harder to remove the pieces.
If the hole in the shaft is not the same size as the slip clutch and a snug fit it will be getting hammered back and forth every power cycle and will fail eventually.
Also if the threads of the bolt are in the plane of the shearing force the strength will be greatly reduced.
Also over tightening a shear bolt will change it's shear strength.

In my opinion the slip clutch should be adjusted to protect the implement,
if I have 80 HP on an implement that is rated for 40 HP the clutch needs to give when more then 40 HP is applied or when an obstacle is struck which results in more then the recommended power to keep rotating..

Amen Lou. I still am not clear on exactly how this catastrophe happened. So a bolt (which really should not have been viewed as a shear bolt) does shear and things go whirling on with inertia ... so what? How does that create all this damage? Among other things I am not a fan of mixing shear bolt protection with slip clutch protection. Splined shafts that do not slip go with slip clutches and controlled slip.

 

[Gord Baker]

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.

The shaft and bore have to be smooth for the Shear Pin to work.
The Grade 8, Grade 5 designations are for Tensile (pulling strength) NOT Shear strength. I don't know if there is a difference. What is RC? Remote Clutch?

 

[charles todd]

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.

My Rhino 172 is setup like that. Sheared many of grade 8, 1/2" bolts between the slip clutch and gearbox. It has a circlip, snap ring, something. It never did anything but spin on the shaft when bolt would break.

CT