Where to buy Shear Bolt?

Where can I buy a Shear Bolt? Who sells these? Maybe they're also called Breakaway bolt
It's for the PTO on an off-brand brush cutter.

Size is 1/2 inch or Half inch by 3 inches.

My local farm and home doesn't have them. I can't find them on Shoup or Sloan. I called a Bush Hog dealer and they only know how to find stuff if you have a part number.

Question: Is a Shear Grade 5 different than a regular Grade 5 bolt? I assume it is.

Seems I can use either Grade 2 or Grade 5 shear bolt for this.

Thank you!

A very few Ive run into have a weak spot, a thinner spot to shear. Very rare.... specialty bolt.

Usually they are just a bolt, but it might be a 2, a 5, or even an 8.... you need to match what the original manufacturer designed it for.

Usually they should shear in the regular part of the bolt, not in the thread area. This can be a problem with just a bolt from a hardware bin, the threads might be longer and get back to the shear area.

So, Im no help at all....

Paul

Personally, I have always just used a bolt from the local hardware store of the proper grade for over 60 years. As others have said, the key is to match the grade bolt that it was designed for and try to keep the threads out of the shear zone.

Typically a higher grade is used for a shear bolt. Lower grades bend instead of snapping off. Just get a 5 grade from the hardware store. I've never had a problem on my mower.

All I've ever used, grade from TSC No problem.

a quick search found them on amazon at just over $10 each.

You might check the hardness/toughness roughly by a file test or hitting with a center punch, the same force as close as you can with each and compare the dimple and maybe by bending each with a vise and wrench.

If the old bolt looks like a regular bolt with three tick marks on the head, it's just a regular bolt.

The whole point of the tick marks on the head are to indicate the bolt is made to a standard, in the case of three ticks, Grade 5. It is to indicate that they are NOT special.

Any farm store should have them sold by the pound.....cheaper than ringing up individual hardware that costs a few cents. Get yourself a spare hardware bin and fill it up with your Grade 5 bolt included.

My bush hog is an off brand too, International World Ag or something like that. It has a half inch shear bolt as well, 1/2 inch grade two, basically the standard half inch bolt from Lowes or Home Depot. If you have a manual of can find one online, it will give you the specs for shear bolt.

Regular 1/2 inch bolt of the right length and tighten it tight and keep it tight. Buy a handful, bolts are cheaper than gearboxes.

1/2 inch by 2 3/4 is the perfect shear bolt, but no one stocks it. So back to a 3inch bolt with lots of thread hanging out. I bump to to grade 5 or 3 marks on the bolt head. The grade 2 or 3 bolt is way too soft and will snap just hitting fire ant mounts and heavy weeds and very light brush. Even the black grade 5 will snap fairly often in brush but at least you can get by with about 10 bolts a day in clearing brush, and a couple of weeks on just grass and weeds. Every shredder tractor is sent out with a bag of 10 bolts and nuts along with two wrenches when we're shredding. (brush hogging) Tractor supply sells them by the pound vs the grade.. so I buy the black bolts... and the silver nuts and washers in separate bags so they can be weighed and priced correctly. The silver bolts sadly are probably from the land of not quite right... and therefore useless as shear bolts... from most stores today. I do not use the gold grade 8 bolts (five marks on the head) to prevent damage to my equipment. ymmv.

get along enough bolt that the threads are not in the shear area.

Jim

I have been useing 1/2x3 1/2 grade 2 bolts for years. Break couple a year maybe.

Scroll over to the LH side of the Home Page and look under RESEARCH & INFO for the TORQUE VALUE Chart listed and you will find all the info on how Bolt Heads are marked. THREE equal hash marks indicates GRADE 5. Works fine for a SHEAR BOLT. Use a 5/8-18 HEX HEAD shoulder bolt, lockwasher, and hex nut. A shoulder bolt has a partial non-threaded end under the head. Grade 2 is softer and also can work. Use on a brush hog or finish mower. Made to break away if obstruction is hit so you don't do damage to your gear box. Helps to also use with an ORC (Over Running Clutch). Bolt length only needs to be long enough to cover the washer and nut with 2 or 3 threads exposed. Longer does nothing. Brush hogging tip: always walk the area first to uncover any hidden objects that will obstruct damage gear box. Look for old stoves and fridges, cars, stumps, large rocks/boulders, Jimmy Hoffa, etc. Question is why are you breaking so many shear bolts???

5/8-18 X2-3/4 HEX HEAD BOLT, PARTIALLY THREADED (SHOUDLER) BOLT:
https://www.mcmaster.com/products/screws/hex-head-screws~/medium-strength-grade-5-steel-hex-head-screws/thread-size~5-8-18/length~2-750/length~2-75/length~2-3-4/

PKG of 5 for $8.70


Tim Daley (MI)
TORQUE VALUES & ID MARKS

My mowers use a Grade 2 bolt with nyloc nut. I'd start with a Grade 2 and if it keeps shearing on you, then consider moving up to a Grade 5. As mentioned, no reason to rush out and replace the gear box.

If your manual calls for a grade 5 shear bolt, it is a grade 5 bolt. Grade 2 is softer and may shear too easily. As others have posted the bolt shank should run completely through the yoke so no threads are in the shear areas. Use a nylon locknut. You can add a flat washer or two if needed so the nut tightens the bolt. You can cut the excess threads off if you want to reduce the chance of anything being caught on the exposed threads.

These folks are pretty good at specialty fasteners or any fastener for that matter.

Local mom and pop company that's grown fairly large. If you call, you'll talk to a real person who will try to help you.

Gerrit

Robnet Supply Inc
Fastener supplier
Baltimore, MD (410) 247-7273