Snow blower break shear bolts under light load.

[Glenn S]

Hello all. Winter has arrived and I am having trouble with my snowblower. It's a 7 ft Farmking, 540 PTO, with a gearbox. When I run the unit empty there is no vibration in the PTO shaft and in the impeller. There is a slight wobble in the auger (7 ft wide) maybe and 1/8 in up and down at 540 speed. Everything seems tight but I continue to break shear bolts, it has 2 in the PTO input shaft which are 5/16 inch grade five, and 1 on the impeller shaft, a 1/4 inch grade five. These are the bolts recommended in the manual. It will break bolts, usually all three and it doesn't matter if it is a light load or pushed to the max. I'm really stumped, anyone got any ideas? I've run it at 540 RPM and slower but it makes no difference they still break.

 

[DustyRusty]

If it is new, I would contact the selling dealer or the manufacturer. Doesn't sound normal to me. Could it be that you are using the wrong bolts? Shear bolts have grooves cut in them to facilitate their breaking when something stops the auger from turning. Your snowblower might call for grade 5 bolts that are not undercut. Check the manual first and see if there is a part number for the bolts or if it just says "grade 5" and then talk to the dealer and manufacturer. Also, there might be something loose in the blower that the snow causes it to move out of alignment and possibly be hitting some part of the blower housing causing the shear bolts to break.

 

[Dave_eng]

/

If it is new, I would contact the selling dealer or the manufacturer. Doesn't sound normal to me. Could it be that you are using the wrong bolts? Shear bolts have grooves cut in them to facilitate their breaking when something stops the auger from turning. Your snowblower might call for grade 5 bolts that are not undercut. Check the manual first and see if there is a part number for the bolts or if it just says "grade 5" and then talk to the dealer and manufacturer. Also, there might be something loose in the blower that the snow causes it to move out of alignment and possibly be hitting some part of the blower housing causing the shear bolts to break.

What tractor are you powering the Farm King blower with?
What is the exact model of farm King?
Is this the first season you have had this issue or is it your first season with the blower?
Who adjusted the length of the pto shaft?
If the tractor has more than one pto speed, how to you confirm you are using the design speed of 540 rpm?
Do you have a tach you could measure the pto speed/?
A worn auger chain with stretched portions can apply shock loads to the drive train.
Please post photos of good and broken both styles of shear bolts.
The model 840G Farm king which is a model from 2012 shows 3/8" and 5/16" shear bolts.

Dave

 

[2zl]

Lift the blower off of the ground ,turn your pto off and shut your tractor off. Make sure nothing is still turning, then check that you can turn the blower easily by hand. If it turns easily find a flat place, lower it and verify its level. Your 3 point hitch top link may be too long and causing your auger to be pressing on the ground.
Hope this helps

 

[Nicksacco]

Lift the blower off of the ground ,turn your pto off and shut your tractor off. Make sure nothing is still turning, then check that you can turn the blower easily by hand. If it turns easily find a flat place, lower it and verify its level. Your 3 point hitch top link may be too long and causing your auger to be pressing on the ground.
Hope this helps

And to add to this: Ensure that the unit itself is turning freely (with no PTO connection) without binding. Binding adds a ton of resistance.

 

[Glenn S]

/
What tractor are you powering the Farm King blower with?
What is the exact model of farm King?
Is this the first season you have had this issue or is it your first season with the blower?
Who adjusted the length of the pto shaft?
If the tractor has more than one pto speed, how to you confirm you are using the design speed of 540 rpm?
Do you have a tach you could measure the pto speed/?
A worn auger chain with stretched portions can apply shock loads to the drive train.
Please post photos of good and broken both styles of shear bolts.
The model 840G Farm king which is a model from 2012 shows 3/8" and 5/16" shear bolts.
View attachment 90918
Dave

Dave it's on a New Holland Boomer 50, 50 engine HP, hydro unit so it is a low-power tractor for a blower that size but here in Alberta we get powdery snow and I can creep along at whatever speed necessary. It's 540 rpm. It's and 840G Farmking
The owner's manual FK313 092010 snow a 5/16 grade 5 shear bolt
I have not adjusted the length of PTO shaft there is about 8 inches of slide for hook-up.

/
What tractor are you powering the Farm King blower with?
What is the exact model of farm King?
Is this the first season you have had this issue or is it your first season with the blower?
Who adjusted the length of the pto shaft?
If the tractor has more than one pto speed, how to you confirm you are using the design speed of 540 rpm?
Do you have a tach you could measure the pto speed/?
A worn auger chain with stretched portions can apply shock loads to the drive train.
Please post photos of good and broken both styles of shear bolts.
The model 840G Farm king which is a model from 2012 shows 3/8" and 5/16" shear bolts.
View attachment 90918
Dave

It's a farmking 840G. The tractor is 50 hp New Holland Boomer 50 hydro. It's a big blower for this tractor but we have powdery snow and I can creep along at any speed. It onlt has 540 PTO.
I have not adjust shaft lenght it has about 7 inches of slide.
The owners manual says 5/16 grade five bolts, and they fit snug into slots. A 3/8 would be too big.
It's not my first season I have used it for 6 yeras and it would break shear bolts once and a while but is worse now. The bolts break cleanly, they don't look stressed.
I'm thing that I shoud maybe replace the chain, it got some rust on it and I soaked it with penitration oil...maybe it is binding??
I think my top link is adjusted OK as per picture. The PTO shaft is near level as well.

 

[ctfjr]

is it possible the chain is catching on something?

 

[Glenn S]

is it possible the chain is catching on something?

when I take the PTO off I can sping the auger, it takes effort so that's why I think mage the chain links are binding, maybe there is rust on the inside of the links, enough to cause drag......I'm clutching at straws here

 

[Glenn S]

Dave it's on a New Holland Boomer 50, 50 engine HP, hydro unit so it is a low-power tractor for a blower that size but here in Alberta we get powdery snow and I can creep along at whatever speed necessary. It's 540 rpm. It's and 840G Farmking
The owner's manual FK313 092010 snow a 5/16 grade 5 shear bolt
I have not adjusted the length of PTO shaft there is about 8 inches of slide for hook-up.








It's a farmking 840G. The tractor is 50 hp New Holland Boomer 50 hydro. It's a big blower for this tractor but we have powdery snow and I can creep along at any speed. It onlt has 540 PTO.
I have not adjust shaft lenght it has about 7 inches of slide.
The owners manual says 5/16 grade five bolts, and they fit snug into slots. A 3/8 would be too big.
It's not my first season I have used it for 6 yeras and it would break shear bolts once and a while but is worse now. The bolts break cleanly, they don't look stressed.
I'm thing that I shoud maybe replace the chain, it got some rust on it and I soaked it with penitration oil...maybe it is binding??
I think my top link is adjusted OK as per picture. The PTO shaft is near level as well.

View attachment 91012





View attachment 91010



What should proper chain tension be, how much defections should the chain have?



View attachment 91009

 

[Glenn S]

when I take the PTO off I can sping the auger, it takes effort so that's why I think the chain links are binding, maybe there is rust on the inside of the links, enough to cause drag......I'm clutching at straws here

 

[DustyRusty]

A new chain can be had at most tractor supply stores, and are easy to replace. Just take the old one with you for the size, and ask them how to cut the links to get the correct size. I could explain it, but it will take a lot of words to do so. If you buy a 10' length of chain, you can make ups a few chains to have as spares. Lubricate the chain with chain bar oil to keep it from rusting in the future.

 

[Dave_eng]

The only other factor that comes to mind is over tightening the shear bolts. Try using a nyloc nut and just snug it up. You are just trying to have the shear bolt in place when it is needed. It is not securing anything.
Dave

 

[mikester]

when I take the PTO off I can sping the auger, it takes effort so that's why I think mage the chain links are binding, maybe there is rust on the inside of the links, enough to cause drag......I'm clutching at straws here

if you take the pto shaft off everything should spin smoothly and easily and no metal on metal rubbing anywhere. You need to find your source of binding.

I bought my Lucknow blower used and disassembled it for sandblasting and painting. When I pulled the secondary fan if found the shaft jamb packed with binder twine and some fence wire.

Also take a good look at your PTO spider bearings.

 

[GBJeffOH]

when I take the PTO off I can sping the auger, it takes effort so that's why I think mage the chain links are binding, maybe there is rust on the inside of the links, enough to cause drag......I'm clutching at straws here

If you fluid film the chain I think it will loosen right up.