Hesston 1120 breaking PTO bolt

Bkpigs · Jun 9, 2019

Can't seem to figure out why I keep shearing the bolt in the PTO shaft by the slip clutch. Can't see anything binding and it keeps going after it snaps.

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Tx Jim · Jun 9, 2019

How long if ever has it been since you loosened the nuts & slipped the linings on slip clutch to be sure they're not rusted/stuck then readjusted nuts?

Bret4207 · Jun 9, 2019

Check your sway bar (knife drive) and knife head. Is there any sense of "pounding" when the knife is running? If so that's the sway bar bushings. Cheap fix now, expensive after you bust the knife head. Been there, done that, got the tee shirt!

pms · Jun 9, 2019

Is slip clutch adjusted properly?
Is the slip clutch locked up?
Roll pressure too tight/heavy Hay?
Slugs of hay through conditioning rolls?
Using the right shear bolts?
Cycle bar binding?

Janicholson · Jun 9, 2019

That slip clutch is not adjusted, it is locked. Coil bind is when a coil spring has reached its shortest length,
and the coils are touching each other. Its not possible for the spring to work because the coils cannot compress
further. Loosen the bolts holding the springs nearly off the threads. and drive the mower making it slip. the
next step is to tighten the springs equally and in steps until (in typical tall hay) it no longer slips. If the
mower keeps going, the bolt is to hold the clutch to the shaft, and not a shear bolt. It is shearing because either
the tractor/mower geometry is pushing or pulling on the clutch radically, not good. If the drive shaft is in a
normal position in your picture, it is running at an excessive angle and will cause noise and vibration. Jim

Steve@Advance · Jun 9, 2019

Jim, that's what I wonder about.

How can a clutch exposed to rain and never released, not rust and stick together?

jm. · Jun 9, 2019

They do, ever operators manual you pick up will tell you to back the nuts off when you start and slip the clutch as Jan says. Even selling new cutters we have to back the nuts off and slip the clutch before they leave the lot. One compressed to run position can freeze up in short time just setting out on the lot. However the slip clutch being stuck is not this guys problem. He has a binding shaft where it is suppose to slip causing the shaft to pull or push and shearing the bolt.

Bkpigs · Jun 9, 2019

I will check the PTO shaft for free movement in and out and loosen the slip clutch bolts as suggested. I don't notice any excessive pounding, all the bushings and bearings in the sway bar are tight

Bkpigs · Jun 9, 2019

Oh, and this is not the running position. It is backed in the shop.

Bret4207 · Jun 10, 2019

Looking at that pic again, I agree it appears the clutch springs look to be compressed to their limit. (Good catch janicholson!) That is sometimes done when someone doesn't figure out the cause of the clutch slipping. Time to get in there and check things out.

JD23Kendall · Jun 10, 2019

Use a nonharden bolt,
grade 0, harden bolts
shear easy

Hesston 1120 breaking PTO bolt

Bkpigs

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Tx Jim

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Bret4207

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pms

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Janicholson

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Steve@Advance

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jm.

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Bkpigs

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Bret4207

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JD23Kendall

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