Shear pin strength

[JMynes]

On my gravel driveway, at least until everything really froze solid, I was going through several shear bolts almost every time I used the blower. Even now when I try to clean up the street mess I manage to hit serious chunks of ice & shear a couple. I found this place: Bolt Depot - Nuts and Bolts, Screws and Fasteners online
to be a great source. they had the metric size / grades I needed and shipped very quickly. One hundred pairs each (bolt and captive nut with nylon insert) of 2 different shear bolts with shipping was under $40.

A pound, maybe 25-30 pieces, of 1/4-20 x 1.5 grade 2 bolts at TSC was like $2. Most of the time when it shears I can recover the nyloc nut and reuse it.

 

[freddyr]

Be aware that if your pin is now a 10mm then the actual size is now at least .393 which obviously greater than 1/4 (.250)

I would personally try a standard 3/8-16 bolt (.375 diam) and see how sloppy the fit is. You could go up in size to a 7/16 bolt (.437) but I would then worry that it would be too strong and defeat having a shear pin in place. And the grade 5 would be OK in the 3/8" diameter.

thanks, upon review, my book lists two differant shear pins. Goig by what u said ,i guess ineed the other one which is m6x40 grade 8. so now i will check that out because the other one is too big! thanks for the heads up!

 

[SARG]

Here's a conversion chart.

inch/mm CONVERSION CHART

 

[Jay4200]

Be aware that if your pin is now a 10mm then the actual size is now at least .393 which obviously greater than 1/4 (.250)

I would personally try a standard 3/8-16 bolt (.375 diam) and see how sloppy the fit is. You could go up in size to a 7/16 bolt (.437) but I would then worry that it would be too strong and defeat having a shear pin in place. And the grade 5 would be OK in the 3/8" diameter.

My PTO uses an M8 (grade 6.6) bolt. When I got the blower, the PO had put in a std snowblower (5/16") shear pin. I went through a couple of those at $3.50 each, but couldn't (and still can't) find grade 6.6 metric bolts. I replaced it with a std 5/16" bolt. I can live with the extra 0.00246" space.

JayC

 

[Chilly807]

My PTO uses an M8 (grade 6.6) bolt. When I got the blower, the PO had put in a std snowblower (5/16") shear pin. I went through a couple of those at $3.50 each, but couldn't (and still can't) find grade 6.6 metric bolts. I replaced it with a std 5/16" bolt. I can live with the extra 0.00246" space.

JayC

I believe 6.6 is equivalent to grade 2 in the SAE system, and grade 5 is very close to 8.8 in metric.

I've never seen 6.6 either, although I haven't looked for it specifically.

Sean

 

[chopped]

On my gravel driveway, at least until everything really froze solid, I was going through several shear bolts almost every time I used the blower. Even now when I try to clean up the street mess I manage to hit serious chunks of ice & shear a couple. I found this place: Bolt Depot - Nuts and Bolts, Screws and Fasteners online
to be a great source. they had the metric size / grades I needed and shipped very quickly. One hundred pairs each (bolt and captive nut with nylon insert) of 2 different shear bolts with shipping was under $40.

You might concider getting a slip clutch from agri supply This is my first year using it, and i have it set to slip before the shear pin breaks.. Its jammed a couple times and havent broken a pin yet (knock on wood).

 

[Scotty370]

I keep two cheapy, (read Harbor Freight) 7/16 wrenchs onboard and several 1/4" Gr/5 bolts, and nylock nuts. I find that torquing is the key! Tighten it too much,Bang, Tighten it too little, the 'slop' will shear it! Tightened just right, it will last for the season.........~S