Shear pin strength

[Jay4200]

You could probably do better ordering those on the internet and have them delivered. Here's one source.

Even that place doesn't carry grade 6.6 bolts.

JayC

 

[Usta]

On my snowblower I drilled a dozen holes in the cover shield over the auger drive shaft. This is where I bolt 6 spare PTO shear bolts and 6 spare auger shaft shear bolts.
No hunting or trying to remember where I put that little bag of bolts.
May sound crazy but if you saw all the stuff and hiding places in my garage you would understand my logic.

 

[Jay4200]

On my snowblower I drilled a dozen holes in the cover shield over one of the auger drive shafts. This is where I bolt 6 spare PTO shear bolts and 6 spare auger shaft shear bolts.
No hunting or trying to remember where I put that little bag of bolts.
May sound crazy but if you saw all the stuff and hiding places in my garage you would understand my logic.

My L4200 has a little mini-trunk that is right behind the seat between the rear fenders. Took me 6 years of ownership before I found that it opened up and there was a cubbie-hole in there. I bet most tractors have the something similar - Kubotas anyway. That's where I keep my extra shear bolts, along with a couple of spare 3pt hitch locking pins.

 

[Danno1]

...... because they are all too retarded to run the register systems. ............


As much as I hate Home Depot, I don't go to Lowes anymore - they are far worse than HD when it comes to raw stupidity of employees (and they are more expensive than HD).


JayC

Well I found that at both of them, the cashier could not tell me the size of a standard sht of plywood. In inches or feet!

I didn't have the heart to complain to management.


.

 

[SARG]

My Martin Meteor 51" blower used the same size shear bolts. After I used the five bolts that I got with the unit I drilled out the PTO housing to accept standard 1/4 -20 bolts. ( .015 larger than 6mm) I now buy them bulk by the pound at TSC and use the grade 5.

Last year I went through about a dozen and so far this year ..... none yet.

 

[Usta]

My Martin Meteor 51" blower used the same size shear bolts. After I used the five bolts that I got with the unit I drilled out the PTO housing to accept standard 1/4 -20 bolts. ( .015 larger than 6mm) I now buy them bulk by the pound at TSC and use the grade 5.

Last year I went through about a dozen and so far this year ..... none yet.

I bought my metric PTO bolts M6X40-8.8 at TSC. Did not break the bank but if I can avoid metric I will. I am going to drill out my rig.
Thanks for the tip!

 

[JMynes]

Yep, drilled mine out too. Now the blower takes just one size shear pin, instead of two. PTO takes 1.5 inch length, the auger 1 inch, but I can get the 1.5 inch bolt in there if I "Use the Force".
I HAVE used grade 5 on the PTO, but I try not to. Grade 2 works nice, and hopefully shears quicker if needed.

 

[freddyr]

ok very interesting. I have a kubota b2789 rear pto blower. it uses a m10 x 1.25 8.8 part # 70060-02609 my question is if i also dill out the hole for 1/4 bolt which strength do i use? I'm waiting now for a delivery of shear bolts from my local Kubota place. I like to make life easy and not pay 3.50 for a shear pin. thanks:thumbsup:

 

[SARG]

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.

 

[ctgoldwing]

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.

 

[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