Shear Bolts??

[FTG-05]

SAE or inch bolts have hash marks to indicate grade; metric bolts have arabic numerals to indicate class. A web search will turn up charts of the various markings and the equivalence of grade and class. As I understand it, the alpha-numeric characters on bolt heads are a code so the manufacturers, distributors, vendors, and others who are privy to the codes (like the check-out clerk at a box store) can identify the bolts without calipers and thread gauges.

You make it sound like that chart is easy to find. It isn't.

Fortunately, Post #7 has proven this to be true.

 

[BenjiMac]

I recently purchased a snow blower. Last night I broke my first shear bolt. Fortunately, the manufacture sent a few extras. However, in trying to find replacements, I am coming up empty. Contacting the dealer of the blower has resulted in crickets, and the manufacture doesn't have a parts section on their website.

I need M10x55 cl 8.8 bolts. As many as I can get.

I would typically install a slip clutch on this implement, but I dont think it would work in this situation. Not to mention the lack of space for one.

Any help is greatly appreciated.

Tractor Supply sells suitable bolts. You can get high quality strong bolts, but don't, the point is to have something that breaks before the other parts.

 

[joea99]

You DO NOT want to use "normal" bolts in place of a shear bolt, regardless of grade. If you value your equipment that is. They are designed to shear, cleanly, to protect the drive line.

Every shear bolt I have seen has a groove in it to break clean at that point which- makes is a relative snap (get it?) to remove. "Make do" parts run the risk of breaking too easily, being a pain, or not soon enough, risking damage, or jamming in the hole and being a royal PITA to remove.

Keep searching for "shear bolts". Someone has to support the thing.

 

[tjandrews]

I recently purchased a snow blower. Last night I broke my first shear bolt. Fortunately, the manufacture sent a few extras. However, in trying to find replacements, I am coming up empty. Contacting the dealer of the blower has resulted in crickets, and the manufacture doesn't have a parts section on their website.

I need M10x55 cl 8.8 bolts. As many as I can get.

I would typically install a slip clutch on this implement, but I dont think it would work in this situation. Not to mention the lack of space for one.

Any help is greatly appreciated.

Our Frontier (aka John Deere) blower has two shear bolts, one in the universal and the other in the auger driveshaft. The manual has the specs - universal is an SAE size and the auger drive is metric. I got replacements at the JD dealer once, but that green paint they use must have real gold mixed in. I get them at Tractor Supply now.

A hint: We broke a LOT fewer bolts when we dropped the shoes so that on rough or grassy surfaces it never digs into the dirt. Leaves a bit of snow in the driveway, but not so much that we can't drive through it.

 

[etpm]

You DO NOT want to use "normal" bolts in place of a shear bolt, regardless of grade. If you value your equipment that is. They are designed to shear, cleanly, to protect the drive line.

Every shear bolt I have seen has a groove in it to break clean at that point which- makes is a relative snap (get it?) to remove. "Make do" parts run the risk of breaking too easily, being a pain, or not soon enough, risking damage, or jamming in the hole and being a royal PITA to remove.

Keep searching for "shear bolts". Someone has to support the thing.

My County Line PHD instructions say to use grade 2 bolts to connect the auger to the gearbox and the drive shaft to the gearbox. Shear bolts are not specified, just plain grade 2 bolts.
Eric

 

[ptsg]

You DO NOT want to use "normal" bolts in place of a shear bolt, regardless of grade. If you value your equipment that is. They are designed to shear, cleanly, to protect the drive line.

Every shear bolt I have seen has a groove in it to break clean at that point which- makes is a relative snap (get it?) to remove. "Make do" parts run the risk of breaking too easily, being a pain, or not soon enough, risking damage, or jamming in the hole and being a royal PITA to remove.

Keep searching for "shear bolts". Someone has to support the thing.

I understand what you're saying and have seen those style of shear bolts, however, I have yet to see an Ag implement that uses those style of shear bolts instead of the simple bolt. As long as the grade matches the original, it will be just fine.

The PTO shaft for my mower just uses a simple Grade 8.8 M8 bolt, however the style of the yoke makes it much easier to replace the shear bolt and definitely won't get stuck.

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[Captain Dirty]

My Italian Goldoni snowblower (10 HP) specs M6 class 12.9 (176,900psi) shear bolts; my American Lorenz (max 40 HP) specs 1/4-20 grade 5 (120,000psi) shear bolts. The M6 bolts shear at a spot closer to the axis of the shaft than the 1/4" bolts. I trust the engineers knew what they were doing. OTOH when Chinglish instructions mention a strange size--for example 1/4-18 (not 1/4-20 or 28, not 5/16-18) I question what other attention to detail is lacking.

Conventional wisdom is that "softer" grades will bend and distort, "harder" grades are more brittle and will snap. The design engineers can compensate for increased strength of the steel by decreasing the cross section--specifying a smaller bolt or machining groves. Kneeling on snow in sub-freezing weather, working in the shadow cast by the tractor's work lamps, trying to drive a bent bolt out with a hammer and drift will quickly convince one that grade 2 bolts are too soft.

 

[RickB]

Many people just can't grasp that "shear bolt" specifications are application specific. Often they are standard hardware of particular dimensions and hardness and sometimes they are purpose designed (or chosen from a specific existing design) for a given application.

 

[manzer7]

I recently purchased a snow blower. Last night I broke my first shear bolt. Fortunately, the manufacture sent a few extras. However, in trying to find replacements, I am coming up empty. Contacting the dealer of the blower has resulted in crickets, and the manufacture doesn't have a parts section on their website.

I need M10x55 cl 8.8 bolts. As many as I can get.

I would typically install a slip clutch on this implement, but I dont think it would work in this situation. Not to mention the lack of space for one.

Any help is greatly appreciated.

Mine use Grade 5 1/4 inch bolts on my JD 1025R 54" Snowblower.

 

[etpm]

My Italian Goldoni snowblower (10 HP) specs M6 class 12.9 (176,900psi) shear bolts; my American Lorenz (max 40 HP) specs 1/4-20 grade 5 (120,000psi) shear bolts. The M6 bolts shear at a spot closer to the axis of the shaft than the 1/4" bolts. I trust the engineers knew what they were doing. OTOH when Chinglish instructions mention a strange size--for example 1/4-18 (not 1/4-20 or 28, not 5/16-18) I question what other attention to detail is lacking.

Conventional wisdom is that "softer" grades will bend and distort, "harder" grades are more brittle and will snap. The design engineers can compensate for increased strength of the steel by decreasing the cross section--specifying a smaller bolt or machining groves. Kneeling on snow in sub-freezing weather, working in the shadow cast by the tractor's work lamps, trying to drive a bent bolt out with a hammer and drift will quickly convince one that grade 2 bolts are too soft.

I suppose engineers can also engineer for the soft grade 2 bolts too, otherwise why specify grade 2 bolts? I have sheared grade 2 bolts with the Bush Hog. They sheared cleanly and were easy to get out. If my Tractor Supply sold PHD instructions said to use something different I would. As it is I have 4 grade 2 bolts in the plastic screw top tube that came with the PHD, along with the instructions. The tube stays with the PHD. I will not be using anything else because anything else is not specified on the instruction sheet and I don't want to break my PHD.
ERIC

 

[rredhawkk]

I don't have a blower for my tractor but for my small snowblower I buy regular bolts at a hardware store. Where the shear pins are ground down to break I use a hack saw and cut 1/4 to 1/3 thru the bolt at the same place and they work fine and at a much cheaper price.

 

[rredhawkk]

I use regular hardware store bolts not hardened bolts and cut them where the shear pins are cut/ground down to snap and hack saw them 1/4 to 1/3 thru and that works fine for me on my small walk behind snow blower. Much cheaper than buying store bought shear pins.

 

[rredhawkk]

Sorry for the double reply

 

[hugo454]

I found the shear bolts for my chipper at Lowes

 

[RoyJackson]

Metric 8.8 is equivalent to SAE grade 5.

Nothing magic here, just follow your manual and go wherever you normally buy bolts.

Yep...that's the grade my blower uses (2 of them).
Just don't mistake a Grade 8 (US rating) for a Grade 8.8 (metric). Grade 8 (US) is way too strong...probably bust your snow blower before the bolt gave way

 

[Cycledude]

Also make sure the bolt is tightened properly, if the bolt is to loose that will allow it to stretch before it shears and possibly make the sheared bolt difficult to remove.

 

[Jchonline]

I thought shear bolts were supposed to be grade 2?
Grade 5? Thats easy!

Unless you get them from Tractor Supply…then they break easily.

 

[RickB]

Sorry for the double reply

Replies can be deleted by the author.

 

[Kschwennsen]

not to sound like an engineer but what are you hitting that you are breaking shear bolts? regardless of what you use for shear pins, try to make sure your plow area is clean, clear of debris and your machine is cleaned after blowing to make sure there is no blocks of ice frozen in the auger(s). Prevention is better than repair.

 

[RoyJackson]

not to sound like an engineer but what are you hitting that you are breaking shear bolts? regardless of what you use for shear pins, try to make sure your plow area is clean, clear of debris and your machine is cleaned after blowing to make sure there is no blocks of ice frozen in the auger(s). Prevention is better than repair.

Very true, but not always possible...