B7100 with 48" King Kutter brush hog

[procraftmike]

I have used a 48" brush mower on my B7100 for several years now. It does a great job and in my opinion, the implement is not oversized. I simply put the tractor in low and 1st gear, if I have some thick brush to go through.

The mower has a grade 2 shear bolt, which I have never sheared. Since I replaced the clutch in my tractor, I have gotten into some thick stuff with the mower that has actually snubbed the tractor. The mower is sized for up to a 40 hp tractor. My B7100 is 16 hp, 13 hp at the PTO.

My question is this, should I be looking at using something softer than a grade 2 bolt to protect my tractor? Apparently, I am not putting out enough power to actually bust a shear bolt. But, could I be causing harm to my tractor?

 

[boz1989]

Grade 2 is a soft bolt, to go lighter, you would have to use a size smaller bolt. I believe the main purpose of a shear bolt is for shock loads, like a big stump or rock.

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[SidecarFlip]

I don't believe you'll harm it. Let it blow some smoke..lol Even my big ones blow smoke once in a while.

 

[D2Cat]

If you're really concerned about abusing your tractor you could use a grinder or a saw and cut a small ring around the center of the bolt to make it weaker.

When coming into a heavier than usual cut, just take less of a swath!

 

[SidecarFlip]

If you're really concerned about abusing your tractor you could use a grinder or a saw and cut a small ring around the center of the bolt to make it weaker.

When coming into a heavier than usual cut, just take less of a swath!

Good idea. Take a hacksaw and cut 1/4 way through the bolt.

My Landpride has a slip clutch on the input end of the gearbox and you could add one. TSC sells Weasler slip clutches with male and female 6 spline hubs. Think they are about 150 bucks.

 

[procraftmike]

If you're really concerned about abusing your tractor you could use a grinder or a saw and cut a small ring around the center of the bolt to make it weaker.

When coming into a heavier than usual cut, just take less of a swath!

But, when a shear bolt shears, doesn't it shear at the 2 ends (just inside the bolt head and just inside the nut), vs. in the middle? Would a cut around the middle help me here?

 

[85Hokie]

But, when a shear bolt shears, doesn't it shear at the 2 ends (just inside the bolt head and just inside the nut), vs. in the middle? Would a cut around the middle help me here?

Mike,

here is the info that you are asking about, just as you thought.

https://images.homedepot-static.com...mart-snow-blower-parts-303160355p-64_1000.jpg

 

[torch]

But, when a shear bolt shears, doesn't it shear at the 2 ends (just inside the bolt head and just inside the nut), vs. in the middle? Would a cut around the middle help me here?

It depends on the design of the interface. If the shear bolt is through a shaft rotating in a tube (ie: perpendicular to the axis of rotation), then any grooves should be located at either end at the inside diameter of the tube (such as Hokie shows)

However, if two shafts meet with a flange on the end of each and the shear bolt joins the two flange halfs (ie: parallel to the axis of rotation) then any groove would be a single groove at the point where the two flanges meet (usually about 1/2 way, give or take).

To put it another way: any grooves need to be at the shear points.

 

[procraftmike]

Thanks everyone! That helps. I just read another interesting thread about fully threaded vs. non threaded bolts and their strengths...with threaded bolts shearing easier. I may just try to find grade 2, fully threaded bolts to use instead of the standard style bolt.

I'd feel better if I sheared a bolt once in a while....lol

 

[Russell King]

You should just remove the shear bolt and make sure the shafts will rotate independently. They may be fused together due to rust, etc.


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