Snapping Flywheel Shear Bolts on a New Holland 276 Super Baler

TrickyT

Member
Have been helping the brother in law do some small bales. He is using an MF390 with a New Holland 276 Super Baler.

I would anticipate we have done 10 acres and 600 bales, but we keep snapping the flywheel shear bolt.

As fat as we are aware everything it set up correctly.

  • PTO turning at 540, with the baler doing 70-75 strokes per minute (book says maximum SPM is 80)
  • There is plenty of hay in the windrow.
  • Ground speed with SPM means it is doing about 10-12 strokes per small bale.
  • Everything greased up and free.
Initially it seemed to do it after turning right on the headland, so we go to the stage of turning off the PTO, which didn't help or slowing down the PTO but it still happened.

Then it has started happening when going in a straight line.

We have checked the bale tension and they are not over tight.

Probably done 10 shear bolts in total. Anyone got any advice?

Trevor
 

db9go

Member
Location
Buckinghamshire
Have been helping the brother in law do some small bales. He is using an MF390 with a New Holland 276 Super Baler.

I would anticipate we have done 10 acres and 600 bales, but we keep snapping the flywheel shear bolt.

As fat as we are aware everything it set up correctly.

  • PTO turning at 540, with the baler doing 70-75 strokes per minute (book says maximum SPM is 80)
  • There is plenty of hay in the windrow.
  • Ground speed with SPM means it is doing about 10-12 strokes per small bale.
  • Everything greased up and free.
Initially it seemed to do it after turning right on the headland, so we go to the stage of turning off the PTO, which didn't help or slowing down the PTO but it still happened.

Then it has started happening when going in a straight line.

We have checked the bale tension and they are not over tight.

Probably done 10 shear bolts in total. Anyone got any advice?

Trevor
Have you checked the needle timing as that controls the ram stop. have you checked the needle brake as if that is loose it will let the needles drop and put the the ram stop in.
What is the bale chamber like is it shine or rusty if it is rusty clear all the hay out as a rusty chamber can make it hard to bale as the increase bale tension is to much for the shear bolt
Are you using the correct shear bolt.
 

TrickyT

Member
Have you checked the needle timing as that controls the ram stop. have you checked the needle brake as if that is loose it will let the needles drop and put the the ram stop in.
  • I assumed it was all ok as it only happened occasionally, but I will check as the brother in law said it was all ok, but I think I need to read the manual to double check!
What is the bale chamber like is it shine or rusty if it is rusty clear all the hay out as a rusty chamber can make it hard to bale as the increase bale tension is to much for the shear bolt
  • I don't actually know as I have never looked.
Are you using the correct shear bolt.
  • Yes, correct shear bolt is being used.

Trevor
 

db9go

Member
Location
Buckinghamshire
Have you checked the needle timing as that controls the ram stop. have you checked the needle brake as if that is loose it will let the needles drop and put the the ram stop in.
  • I assumed it was all ok as it only happened occasionally, but I will check as the brother in law said it was all ok, but I think I need to read the manual to double check!
What is the bale chamber like is it shine or rusty if it is rusty clear all the hay out as a rusty chamber can make it hard to bale as the increase bale tension is to much for the shear bolt
  • I don't actually know as I have never looked.
Are you using the correct shear bolt.
  • Yes, correct shear bolt is being used.

Trevor
What is ground like is smooth or bumpy if its a bit bumpy it could be the needle brake as it only need to move a small amount and it will bring the ram stop.
When you empty the chamber see if there is a build up of chaffy material in the lower corners as that adds to make it harder for the ram to push the bale out that normally happens with a rusty chamber and seeds
 

Cowabunga

Member
Location
Ceredigion,Wales
All the above plus, are you driving too fast? Is the swath lumpy and prone to be pulled in from a distance? Swath made by a Vicon Acrobat or similar wheel rake?
Most likely, in my opinion, is a loose knotter brake or shear bolt bushes that have rounded edges through wear over the years.

Having said that, it may be something else entirely.
 

Dave.p

Member
Arable Farmer
Location
S. Devon
All the above plus, are you driving too fast? Is the swath lumpy and prone to be pulled in from a distance? Swath made by a Vicon Acrobat or similar wheel rake?
Most likely, in my opinion, is a loose knotter brake or shear bolt bushes that have rounded edges through wear over the years.

Having said that, it may be something else entirely.
Check the slip clutch on the flywheel, slacken off the bolts over the springs and make sure the plates aren't stuck together by engaging the pto and letting it slip, then tighten again making sure the springs have a gap between them.
 

Cowabunga

Member
Location
Ceredigion,Wales
Check the slip clutch on the flywheel, slacken off the bolts over the springs and make sure the plates aren't stuck together by engaging the pto and letting it slip, then tighten again making sure the springs have a gap between them.
Yes. Should be slackened off, slipped a bit and retightened to spec at the start of every season. Often forgotten. This lets the clutch slip slightly at every stroke when under heavy load which takes the peak load off the shear bolt and tractor PTO.
 

Goweresque

Member
Location
North Wilts
My brother in law had a NH570 which consistently did this, the ram stop was always just about to catch the ram, he was always doing shear bolts. We managed to adjust the timing to get it to run better but would still do a shear bolt once or twice in a 10 acre field. He finally solved the problem when he replaced the knotter drive chain, it had stretched and meant the timing was impossible to get 100% right. Since replacing that its run like a sewing machine.
 

TrickyT

Member
Many thanks for all the advice. Plenty to go on, will feed back what i find.

I know we have not done anything with the clutch, so that will be the first thing. I did think that if the going got tough, then the clutch should slip before the shear bolt went?

Trevor
 

essexpete

Member
Location
Essex
As others have suggested check the shear bolt holes. If the ground is rough then you can bounce the needles if the brake not adequate. It strikes me that it cannot be far out. If you do adjust make a small adjustment one at a time.
Do the slip clutch as said above.
You do need the moving and static knives sharp and fag paper width as they pass. With an empty chamber use a bar on the ram to see if the gap between the blades might be widening as material is pushed in.
Don't forget to make sure the baler cannot free run when you are fiddling about with the ram.
 

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