Hey all, new tractor owner here. I have a flail mower and I sheared the shear bolt. It sheared when I lifted the flail and the bolt ended up hitting part of the tractor. Can I turn the pto around and have the shear bolt at the flail mower side instead of the tractor side? The pto says which direction it should go, but is there really any difference which side goes where? Thanks.
Pto direction
- Thread starter Guy Mandude
- Start date
BigG
Well-known member
Equipment
l2501, FEL, BB, Rotary cutter, rake,spreader, roller, etc. New Holland TL80 A
All of the PTO shafts that I have seen had the shear pin towards the rear. My question is what hit the PTO shear pin to brake it?
Comer, a world wide manufacturer of drive lines recommends the shear bolt be at the implement end as that is where the shock load enters the system.
Below is their answer to my question in 2017:
The protection device is usually on the implement end. The torque is usually driven by the implement and you want to protect the gearbox.
Dave
Below is their answer to my question in 2017:
The protection device is usually on the implement end. The torque is usually driven by the implement and you want to protect the gearbox.
Dave
Thanks for the replies. On the bx2380, the turnbuckles attach to the tractor with a shackle. With the implement lifted (to go over a log) and still turning, the angle brought the turnbuckle up high enough that the bolt hit the shackle. The only way i knew it was hitting it was the god-awful banging that scared the cr@p out of me. Ha! Thanks again for the replies, i'll turn the PTO around so the shear is at the implement.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
re: Comer, a world wide manufacturer of drive lines recommends the shear bolt be at the implement end as that is where the shock load enters the system.
gee,hmm, isn't the 1st shock load comes from engaging the PTO lever so the shear bolt should be on the tractor side.....?
sure, once the implement is spinning, the 'shock' will, generally ,come from the implement.
As for which end of the PTO shaft, really it doesn't matter, the shear bolt will break. OK, a 'materials engineer' might be able to prove the math on a computer but in the Real World, things are far different !
gee,hmm, isn't the 1st shock load comes from engaging the PTO lever so the shear bolt should be on the tractor side.....?
sure, once the implement is spinning, the 'shock' will, generally ,come from the implement.
As for which end of the PTO shaft, really it doesn't matter, the shear bolt will break. OK, a 'materials engineer' might be able to prove the math on a computer but in the Real World, things are far different !
Unless you can figure out a way to make torque disappear in the drive shaft(without shearing the bolt) doesn't particularly matter which end it's on. Starting the attachment, there's a little 'shock' when the clutches engage, but not that much if you back off on RPM to just above idle before you do. Hitting a stump at full RPM with a rotary cutter (bush hog) on the other hand, transfers an enormous amount of shock to the drive line, and ultimately to the tractor. Whether you shear the pin at the mower differential, or at the tractor, it's somewhat irrelevant. Worst case, with the pin sheared at the far end, you may get some wobble in the shaft.
We added a slip-clutch to our bush hog when I was a kid because without it, there was no stopping the 8N when the PTO was engaged with the mower on there. I put the old 8N in the creek more than once. What a ride that was. But, because of the inevitability of that happening, one of the first things I learned to do was point the nose downhill as soon as possible if I couldn't avoid the situation or just simply didn't turn early enough for the soil conditions (front wheels weren't very grippy and 2WD only) Creek bank tractor diving aside, a slip clutch seems like a better solution with a high inertia load, especially if you're going to be putting that load into bad places. If it's belt driven, the belts will stretch enough to absorb some of the mechanical shock, and probably slip (with a lot of complaining) in the case of a complete mechanical jam. (Rock in a tiller, something REALLY bad in a chipper, etc). Belts should slip before the shear pin breaks, but that's my opinion. Having the shear pin near the tractor might save some of the wobble of the drive shaft (depending on the inertia of the attachment), but it ain't really gonna make much difference in the experience other than moving the unavoidable really bad noises a little bit farther away from you.
We added a slip-clutch to our bush hog when I was a kid because without it, there was no stopping the 8N when the PTO was engaged with the mower on there. I put the old 8N in the creek more than once. What a ride that was. But, because of the inevitability of that happening, one of the first things I learned to do was point the nose downhill as soon as possible if I couldn't avoid the situation or just simply didn't turn early enough for the soil conditions (front wheels weren't very grippy and 2WD only) Creek bank tractor diving aside, a slip clutch seems like a better solution with a high inertia load, especially if you're going to be putting that load into bad places. If it's belt driven, the belts will stretch enough to absorb some of the mechanical shock, and probably slip (with a lot of complaining) in the case of a complete mechanical jam. (Rock in a tiller, something REALLY bad in a chipper, etc). Belts should slip before the shear pin breaks, but that's my opinion. Having the shear pin near the tractor might save some of the wobble of the drive shaft (depending on the inertia of the attachment), but it ain't really gonna make much difference in the experience other than moving the unavoidable really bad noises a little bit farther away from you.
OldPaint, Did you maybe mix-up an overriding-clutch with a slip-clutch in your description? I had a 9N and a rotary cutter much too big for it ...but it worked fine as a “pull-behind” with no toplink mowing 20 acres. A slip clutch will save a drive-line if properly adjusted...but I cannot see how it would prevent a cutter from pushing the tractor unless equipped with an overriding-clutch on the PTO shaft.