PTO Shaft to Gearbox Bolts Keep Breaking!

[Maka]

I had an Iron Craft customer breaking shear pins and found he was buying grade 2 from harbor freight. We put the OEM bolts in and no problem after that.

 

[wirlybird]

I had an Iron Craft customer breaking shear pins and found he was buying grade 2 from harbor freight. We put the OEM bolts in and no problem after that.

Well, since a "shear pin" is a grade 2 bolt was the issue the Harbor Freight bolt specifically?

 

[ning]

Well, since a "shear pin" is a grade 2 bolt was the issue the Harbor Freight bolt specifically?

Some units call for a grade 5 pin/bolt.
I'd expect if the grade 2 were consistently breaking, the situation called for grade 5.
Best to check the manual / manufacturer.

 

[SPYDERLK]

Some units call for a grade 5 pin/bolt.
I'd expect if the grade 2 were consistently breaking, the situation called for grade 5.
Best to check the manual / manufacturer.

Every double shear situation calls for having the bolt shank across both shear lines.

 

[wirlybird]

Some units call for a grade 5 pin/bolt.
I'd expect if the grade 2 were consistently breaking, the situation called for grade 5.
Best to check the manual / manufacturer.

I currently run 7 brush hogs of different makes and models and not one manual calls for a grade 5.

If grade 2 bolts are constantly being broken then my first thought is the cutter is not set up correctly, cutting too low for the terrain and/or frequently hitting or running over stuff it shouldn't be.

 

[ning]

I currently run 7 brush hogs of different makes and models and not one manual calls for a grade 5.

If grade 2 bolts are constantly being broken then my first thought is the cutter is not set up correctly, cutting too low for the terrain and/or frequently hitting or running over stuff it shouldn't be.

That's great!
(insert "big thumbs up" meme here)

I also don't have any equipment with grade 5 shear requirements, but they do exist.
Not everyone's equipment is the same, and you're not the only one reading this.

 

[SPYDERLK]

I currently run 7 brush hogs of different makes and models and not one manual calls for a grade 5.

If grade 2 bolts are constantly being broken then my first thought is the cutter is not set up correctly, cutting too low for the terrain and/or frequently hitting or running over stuff it shouldn't be.

Hmm. I have a Woods HC-60 that came used "like new" with a 1/2" Gr5 shearbolt. We have sheared 2 of them. -- Not myself. I only did the replacing. The shank crosses the 2nd shearline comfortably. I dont know the circumstances that sheared them. Im surprised that much torque can be applied to 5' bushog having a stump jumper. Maybe somebody is engaging the PTO WFO and not owning up.

 

[RayIN]

I use gr 2 bolts. I want the part that breaks to be the easiest to replace, and the cheapest. I usually break 1 bolt every time I use my KK rotary mower. Seems like there is a fallen tree limb hidden down in the grass every time. I carry 2 spares in the tractor toolbox all the time.
I can be back up and mowing in 15 minutes. If the yoke breaks instead of the bolt, it gets expensive, in both time and money.

 

[Maka]

Well, since a "shear pin" is a grade 2 bolt was the issue the Harbor Freight bolt specifically?

We used grade 2 from Iron Craft and no problems.

 

[Maka]

Well, since a "shear pin" is a grade 2 bolt was the issue the Harbor Freight bolt specifically?

I think yes, the problem was they were Harbor Freight. He brought it to us and the bolts he was using and they broke when engaging the PTO at as it should be. We put in OEM bolts and zero problem. Its been a month now and he has come in several times for other things and he has not broken one of the OEM bolts.