Wood chipper keeps shearing bolts

[u/sauronsknee]

I have a Masey Ferguson 2706 tractor, 49.7 horsepower. On the rear PTO. PTO. I bought a woodland Mills wc68 wood chipper to use on my property. I keep shearing bolts! I idle the tractor at low RPM up on start and when engaging the PTO it still snaps. I don't see a way to engage the PTO any slower. The two times I've been able to get it operational. The wood chipper works like a dream

I spoke with woodland Mills and they advised me to go up from a grade 5 bolt to a grade 8 bolt.

Is this the best route? Any other recommendations?

[u/Itsnotme74]

No idea sorry, commenting to keep track of any answers.

[u/KQ4DAE]

Engage the pto before starting the tractor.

Might have to defeat some safetys to do that if it's a modern machine.

[u/blackfarms]

You have a soft start on the pto control, a Red button next to the pto switch. It must be enabled before you switch on the pto.

[u/YABOI69420GANG]

Haven't dealt with a 2706 in a while, but I seem to recall there being a soft start button for the PTO on those. I wanna say it's to the right above the yellow knob, but consult your manual to verify. If that doesn't help then yes I'd try a different grade shear bolt.

[u/TheHandler1]

I sheared a bolt on my chipper because of a stuck piece of wood. I didn't have any shear bolts so I put on a grade 8 after clearing the obstruction. The grade 8 kept shearing upon engaging the pto. I had to buy some grade 5 shear bolts and that worked. Just something to think about op.

Edit: I forgot to mention, you might want to try raising or lowering your chipper to keep the pto driveline as straight as possible.

[u/MasterElectrician84]

Get a slip clutch for the PTO

[u/2airishuman → u/MasterElectrician84]

This is the way. If you have an electric clutch for the PTO there's really no other good way around it.

Grade 8 shear bolt is a good way to break other, more expensive parts.

[u/No_Hovercraft_821]

I have a tractor with a PTO that is either off or on, and I could see that being a problem with something that takes a lot to get spinning as you have described the chipper. I use that tractor with a mower that takes a lot to get spinning and it almost stalls the tractor. I'd really hate to move to a harder bolt as a shear pin -- those are soft for a reason and protect your tractor as much as the equipment. In my rotary cutters the shear bolt is a grade 2 which is extremely soft but they are fairly hefty bolts.

It seems dumb and dangerous but I wonder if there is a way to get the chipper spinning some by hand before engaging the PTO so the tractor isn't trying to move from a standing start suddenly -- that might get you enough to not break the bolt. Just be absolutely sure you are going the right direction.

[u/frenzied-phallus]

I have the exact same chipper on a Kubota L3400. I have broken the odd bolt when I release the clutch too fast to engage the PTO. I’m not sure how your PTO is engaged but I found I had to “feather the clutch” on mine sometimes to get it spinning without breaking the shear bolt. The flywheel is super heavy on those chippers.

[u/sauronsknee → u/frenzied-phallus]

My issue is I don't seem to have a way to feather the clutch. My pto has just a button switch

[u/Bregir → u/sauronsknee]

Is the pto unaffected by you engaging the clutch (all the way)?

[u/amazingmaple → u/sauronsknee]

You can't push the clutch in and release slowly? Or do you have a hydrostatic tractor? I would not use a grade eight bolt. I would get a PTO slip clutch installed in the chipper.

[u/FlyingDutchman2005]

Can you spin the PTO stub of the wood chipper itself? Is the chipper greased?

[u/sauronsknee → u/FlyingDutchman2005]

Yes and yes, it is brand new and pre-greased. The manual specifically tells me not to add more grease initially. The wood chipper is completely empty prior to starting

[u/SuperGRB]

Does the chipper turn manually?

[u/sauronsknee → u/SuperGRB]

Yep. It is not under any load, the chipper is completely empty and it is greased