Bolt Shear

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Sandman north
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Location: Parry Sound Ont

Bolt Shear

Post by Sandman north » Mon Nov 06, 2017 4:55 pm

So my snow blower drive shaft on my tractor has been running a double roll pin or spring pin 1/4 inch diameter X 2"
bent my auger badly last winter and roll pin did not break.7000 psi shear

14 hp Diesel

This summer I spent some nice days straightening everything out. When you don't get what you want you get EXPERIENCE!

I have replace the roll pin with a # 2 bolt shear of 2179 psi
if it breaks all the time I can got to a # 5 bolt with a shear of 3533 psi

Anyone have any thoughts ?

Easier to replace a bolt rather than all the bent auger parts I am thinking.

Thanks

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10KPete
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Re: Bolt Shear

Post by 10KPete » Mon Nov 06, 2017 5:12 pm

Interesting! A few years ago I want through the same exercise with a friends auger. Driven by the PTO and hung on the three-point tractor mount. First went with the "weak" bolt trick, which worked. But when the bolt sheared the ends mashed over enough to jam the broken bit and make it hard to get out. So I used the lathe and a sharp 60* tool to cut shallow "shear grooves" in the bolt shank so the bolt would break cleanly and not jam. Now when the bolt shears the bits just fly out and the bolt is easy to replace.

Since then we found a slip clutch that goes in-line at the tractor PTO and, once adjusted, it slips instead of breaking bolts. Works great!! We leave the "nicked" bolt in place just in case and I think we've only broken one bolt in a couple of dozen holes.

This is a 22 hp machine and an 8" x 48" auger.

You might be able to apply this to your snow auger...

Pete
Just tryin'

John Hasler
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Re: Bolt Shear

Post by John Hasler » Mon Nov 06, 2017 5:50 pm

The manufacturer of my haybine specifies grade 5 shear bolts to avoid the "mashing over" problem.

Russ Hanscom
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Re: Bolt Shear

Post by Russ Hanscom » Mon Nov 06, 2017 6:21 pm

As you note, bolts or pins are cheaper than the alternative. Our farm had a rock pile of a field and it was common to use several pins per tree hole. Went thought boxes of bolts but never messed up a gear box.

Then there was clown we know who got tired of replacing bolts and installed a really high strength one; the bolt survived - but nothing else did.

spro
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Re: Bolt Shear

Post by spro » Mon Nov 06, 2017 7:47 pm

Okay! Grade 5 not 8. thanks

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mcostello
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Re: Bolt Shear

Post by mcostello » Mon Nov 06, 2017 9:32 pm

Worked in an Industry that had a good amount of experience with shear pins for their equipment. The shape of the groove influences how the pin breaks. A "V" breaks all at once where as a "U" releases more slowly.

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10KPete
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Re: Bolt Shear

Post by 10KPete » Mon Nov 06, 2017 9:54 pm

Yep.

Pete
Just tryin'

Sandman north
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Location: Parry Sound Ont

Re: Bolt Shear

Post by Sandman north » Tue Nov 07, 2017 7:04 am

Hi everyone
Thanks for the replies, great replies. I don't have room for a clutch as its a front mount blower & just no room (great idea).

So I am interested in taking a gr 5 bolt and i can cut a grove on the lathe ( U or a V ) I am not sure ?
And how deep ?

For my walk behind blower Airens the shear bolts are square cut i think?


Thanks again

Sandman North

Glenn Brooks
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Re: Bolt Shear

Post by Glenn Brooks » Tue Nov 07, 2017 11:59 am

Sounds like the U shape groove would be ideal. It would cut less deeply also, allowing a bit more shearing force before breaking - hence more longevity, perhaps.

Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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DianneB
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Re: Bolt Shear

Post by DianneB » Tue Nov 07, 2017 12:02 pm

I use plain old cheepie hardware store bolts (grade 0.5? LOL!) on my John Deere 16HP and they work great. They don't let go in normal service but if the blower tries to eat a chunk of ice or a rock, they snap easily. John Deere even has a little bracket right on the blower to hold 5 additional bolts. Going on 40 years in service with nothing busted (except bolts).

Sandman north
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Joined: Thu Jan 29, 2015 8:02 pm
Location: Parry Sound Ont

Re: Bolt Shear

Post by Sandman north » Tue Nov 07, 2017 12:16 pm

it all sounds good

I am going to the shop and cutting some now.


Thanks

John Hasler
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Re: Bolt Shear

Post by John Hasler » Tue Nov 07, 2017 4:39 pm

spro wrote:Okay! Grade 5 not 8. thanks
What does the manufacturer recommend? I use grade 5 on my haybine because that's what Matthews says to use. The bolt clamps two 3/4" plates in a location where a mashed-over grade 2 is *very* hard to remove (Made that mistake. Once.) Grooving does not seem necessary: the grade 5s snap off nicely. On other machines where the bolt clamps fairly thin plates with good access and the ability to separate the plates grade 2 works fine if it's strong enough. The bolt has to be a close fit in the holes and the shear has to be applied to the unthreaded shank, of course.

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