PTO shear bolts. Are they a standard size?

I need some shear bolts as I just have the 1 that came in the PTO shaft that shipped with the brush cutter I bought. 6 foot Howse, category 1 on the 3 point.

I forgot to pull the one I have out and now it's up at my hunting farm 100 miles away.

Are these things all a standard size? A lot of listings online don't give dimensions, but a found a couple that say 1/2 inch by 3.5 inches long.

Are PTO shear bolts a standard dimension?

Grouse
 
I've seen 2 sizes used. My brush hog uses a 7/16 bolt as shear pin but I have seen others use a 1/2 inch one so if I where you I would buy a few of each size at 2, 2.5 and 3 inch long. My local farm and home has them by the pound so I buy a few of each that way I know I have what I need on hand
 
shear bolts are grade 2 bolts .. regrdless of size.. I just go to my Tractor Supply store and stock up... Flail chopper, post hole digger, manure spreader, te al...
 
You need to consider what grade bolt you need. Growing up on the farm, I remember that all of the shear bolts we had were pretty soft, grade 3 or so. The rotary cutter I have now uses a metric size, and they are the equivalent of a grade 5 bolt. Howse are pretty common, check with a dealer to make sure you get the right size and grade.
 
No. My New Holland feed grinder uses a special size. As close as I can get without going to the dealer is to use metric.
 
Many years ago I used to snap them all the time so put in what was called then as case hardened-apparently grade 8 and never had another
problem. Now I use standard that come 5 to a pack at Tractor Supply.
 
I/2 X 3 1/2 sounds about right. The bolt does not need to be that long to go through the universal joint but the reason for using a longer bolt is so that the threads are not in the shear hole. When I had such a machine I used the grade 3 which is the lowest grade
 
What would you rather replace, the correct shear bolt or possibly the gear box someday? I once saw a N-H baler that had grade 8 bolts used instead of the correct grade. The plunger gear box housing was in numerous pieces as well as the gears. There was no warranty on it, even thought our customer cried and whined.
 
My 5 foot Howse cutter uses 1/2 x 3.5 grade 5 bolts and lock nut.
We would need to know what series 6 foot mower you have to look up the bolt you need.


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What grade bolt did John Deere use for the flywheel shear bolt on their older small balers like 14T, 336, etc.? Those were some hard little shear bolts! They sheared with a bright shiny finish across the shear.
 
Standard inch or standard metric? King Kutter used 1/2 x 3.5 gr 2, some JD cutters are metric. I have a slip
clutch now, didn't like changing shear pins in the flies.
 
The shear bolts on a 14T were a special bolt if you look close. We always carried about 5 or 6 of them in twine box on baler all the time.
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Most of mine are ? but I buy longer as I found that with a Grade 2 and not locking the (self locking) nut down tight....leaving a little slop, my replacement
rate has dropped to ZERO!
 
(quoted from post at 08:08:17 09/15/18) Most of mine are ? but I buy longer as I found that with a Grade 2 and not locking the (self locking) nut down tight....leaving a little slop, my replacement
rate has dropped to ZERO!

I will second that.

The tiny bit of play reduces the fatigue that leads to breakage from the repeated small shock loads to almost zero without any noticeable wear on other parts.
While still being there to protect things from the big whoops moments.

Bolt long enough that the threaded portion is not in the shear area then using a nylock style nut tighten the nut up to seat the bolt then back it off a half turn or so, just enough that you can rotate the bolt with your fingers.

A couple of normal nuts jam locked together on the bolt will accomplish the same thing.

The shear pin on many outboard motor propellers are set up as a full floationg design.
I have never had one break under normal use. If the prop hits something substantial (abnormal use) the pin does it's job and shears off.
 

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