Landpride snow blower shear pins?

[Kubota Dave]

I would like to have a few on hand but am not sure which ones i need in the parts list there are a few listed. SB1064

https://www.landpride.com/ari/attach/lp/public/manuals/370-430p.pdf

Thanks

 

[bearskinner]

Just unbolt one, take it with you to a home supply hardware store, and have the attendant get you the same grade, size and length bolt, nut, washers. Measure the location and depth of the “Shear grooves” and turn them down on a lathe ( or have a buddy do it for you) that way you will have a bag full of spares, that don’t cost $5. A piece....... or have the Kubota counter guy order them in, and pay to have them delivered

 

[sagor]

The shear bolt on the auger drive chain seems to be a standard Gr5 bolt, 1/4-20 by 1" long (part 11) with a Nylock nut (part 23).

The main drive shaft seems to have a metric bolt/nut: M8x50 and the grade seems to be 6.6 (C1.6.6), which is an odd grade. Grade 8.8 is close to Gr5. Metric grade 5.8 is close to Gr2. For that bolt/nut, I would take it to a shop to get a better estimate on the grade, and to get the proper one. Strange they mix imperial and metric on the same blower.
It would be safe to use a metric 5.6, it would be weaker and have lower yield strength as a 6.6 bolt, technically.
In metric, first number is 1/100 the tensile strength in MPa, second number is used to calculate the yield strength (first number x second number x 10) in MPa.
So, a 5.6 is 500MPa tensile, and 300MPa yield (yield is where the bolt starts to deform permanently)
A 5.8 would be 500MPa tensile, 400Mpa yield
A 6.6 would be 600MPa tensile, and 360MPa yield
A 8.8 would be 800MPa tensile, 640MPa yield.

Use your favorite Internet conversion utility to make those numbers imperial...
All numbers are approximations... Verify with a bolt supplier for proper bolts.

 

[Kubota Dave]

I guess there is no way to know which ones typically break. It's usually the one you don't have.

How hard is it to shear one? Have not gotten to use it yet.

 

[G.rid]

FYI. 8mm bolt is less than .003" larger than 5/16". Standard sizes may be easier for you to find depending on your local suppliers.

I can't recommend a specific grade bolt, but I can pass on what I've been told. If you use to low of grade, soft bolt, it won't 'snap' when needed, it will smear. Then it can be a bear to replace, over time it could oval the holes. It was suggested a little harder, like a grade 8, then turn a small relief groove where it should shear.

Personally I'd rather deal with replacing more shear pins than the possibility of damaging the blower or something in the tractor. After all, that's why they're there.

 

[KeithG]

The only shear bolt application I can see in the diagram is the HHCS 1/4-20X1 GR5 bolt which looks like it is associated with the auger. I know there are others I just could not specifically identify them.

The only advise I can give you with regard to this bolt specification is that the fully threaded GR5 bolt has a shear failure rating of 2,542 pounds. If the flange is over a non-threaded section of the bolt then the shear failure rating will be 3,534 pounds. That is just about a thousand pounds so I would use the fully threaded bolt if I was not sure.

I would also probably use a 1/4 bolt wherever I thought the bolt was providing shear protection and not a 3/8ths bolt. Just my opinion...

FYI:
BOLT
FINDINGS: Size Size Surface Shear Tensil Shear
(diam): (len): area: capability: strength: Failure (lbs):
Grade 8
not threaded 0.25 1.25 0.049087385 90,000 150,000 4,418

Grade 5
not threaded 0.25 1.25 0.049087385 72,000 120,000 3,534

Grade 2
not threaded 0.25 1.25 0.049087385 44,400 74,000 2,179

Grade 8
threaded 0.212 1.25 0.035298935 90,000 150,000 3,177

Grade 5
threaded 0.212 1.25 0.035298935 72,000 120,000 2,542

Grade 2
threaded 0.212 1.25 0.035298935 44,400 74,000 1,567

-Keith