sheer pin Q

[TC29-dude]

I broke the sheer pin on the old brush hog I picked up when I got my TC29.

I went to the local hardware store and they gave me grade 3 bolts to use, are they too hard? The hardware store guy told me that they were the softest made but I have just found out that that's not true.(from reading here at TBN!) I don't want to use to hard a bolt and screw something else up.

Thanks!

 

[bjcsc]

Are you sure they're grade 3 (two marks on the heads)? Most hardware stores carry grade 2, 5, and 8. Most shear pins are grade 2 bolts (no marks on the heads) and if in fact you have grade 2s I wouldn't worry about it...

 

[SnowRidge]

The marks are little bars. If you are not familiar with them, this website shows the markings and grades quite nicely.

 

[N80]

I've never been clear about this. I always assumed a shear bolt was specifically designed to break at a certain stress level. In other words, the only place you'd use one was in a place that you wanted it to break. But is a shear bolt really just a lower grade of 'regular' bolt?

 

[Kiotimike]

Yes.
Mike

 

[N80]

So technically, it isn't a shear bolt until you put it in a hole that requires a shear bolt.

I'm being silly of course, but at the same time I don't want to walk into the local TSC and ask for a shear bolt and then get directed to the regular bolts and tell the adolescent sales clerk, 'no, I said I wanted a shear bolt'.

I guess I'd rather look stoopid here than in the tractor store.

 

[ToadHill]

I was told years ago that sheer bolts are grade 5's.

 

[TC29-dude]

Thanks for the replies!
My bolts must be grade 2, they have no marking on them other than 3 initials...HKT. I assume that is the manufacturer as that doesn't match up to any of examples show on SnowRiges nifty chart.

I think it's interesting that you can't tell the dif between grade 1 and 2...It seems like that would be a good thing to me.

 

[N80]

I did a little research on the web. And even though this might be a technicality with no practical application here, there are, in fact, pins and bolts designed specifically as shear pins and shear bolts. Many of them are actually grooved at a designed break point. Most of them appear to be used in heavy machinery.

Also, when I asked recently, it was recommended that I use grade 3 shear bolts for a 14" two bottom plow. Does that sound right?

 

[BillyP]

I was told years ago that sheer bolts are grade 5's.

It must be according to what implement you have? I've noticed almost 100% of the people recommend a grade 2 for shear bolts. The only implement I have that uses a shear bolt came with a package of 5 grade 8.8 bolts with self locking nuts. 8.8 is a metric that's almost a perfect match for a grade 5 SAE.

 

[SnowRidge]

I think the manufacturers went to grade 2 bolts, when the realized they could save some money, and their customers wouldn't have to stock a supply of specialized shear pins. I used to have to replace shear pins back in the 70s when I was a GI. Now I replace bolts. The bolts are easier.

 

[bx23barry]

We used to give a helper a few boxes of bolts and a hack saw to make "shear bolts" for snow blowers when they were "bad". Shear bolts are implement specific and there is no standard, but there is nothing wrong with using a "weaker" bolt as long as ya don't mind changing them more often.