I give Up . . . Shear Bolt Grade??

Tall T

Well-known Member
Re, the MF 59 Rotary Cutter

Searched and watched a few videos but still can't find out whether to use a #2 or a #5 grade bolt for a shear pin.

Thanks,
Terry
 
number 2, if you want the shear feature to work, number 5 is harder, it will still shear if enough force is applied to it, but by that time more expensive damage may occure to the machine too
 
Howse recommends 5 but I use 2 and have no shearing problems. However their bolt is 1/2 inch., Start out with 2 and if it appears to shear too easily switch to 5.
 
Use grade 2.
See how well they hold up for you.
You will likely be happy with them.
But you do have about 50% more hp than an N
too.
My 2N with a brand new King Kutter rotary i
sheared the bolt on an ant hill about 50'
into my first run with it.
Then I sheared about 3 more in the next
couple of days of heavy mowing.
I put in a grade 5 and never sheared one in
2 years. But when I swapped the engine from
my 2N into an 8N and wanted to keep a couple
other items - one being the pto shaft - I
couldn't pull it out. So I assumed I (or
some prior owner) had twisted the pto shaft.
Kinda one of those things you don't know
till you know better.
Of course now I have a mower with a slip
clutch - because I know better...
 
Thanks for the good advice everyone.

Jerry,
If I understand you correctly, one can actually twist a PTO shaft without shearing a grade 5. Is that right?

Made a lifting point for the cutter . . . so I wouldn't be scratching paint with multiple chains. :D
I had to re-tap all four upper holes and replace all but one of those bolts and had to re tap those two holes I used for the lift.
I'm using a fat steel ring along with those two hooks. I've had those two pieces for 35 years and each had 2 heavy chain links attached. Never did figure out what they were made for.
38032.jpg
 

The aggravation of a sheered bolt is cheaper than a bent blade are damaged mower.

Not that I adhere to that but have paid the price :(

Its your call I am not much for working on it on the job.
 
Ya'll gonna think we're crazy down here in south Alabama but a grade 5 bolt is too soft as a shear pin due to the fact we have so many fire ant mounds, you would be getting off the tractor every 20 or 30' to change the sheared bolt, most of us use grade 8 bolts and never have a problem cutting pastures, of course if you were to hit a stump you might be in trouble. When my Mother gave me Dad's 601 Ford and Bushhog Squealer two years ago after he passed, I found he was using a grade 10 bolt in it, used to hear him cuss them ant hills all the time.
Grade 5 would be the best in my opinion to use if your worried about damaging your equipment.....
 
A shear pin is a fuse. It's better to be too soft than too hard.

Use grade 2. If you have excessive shear pin failures, change to grade 5.

Dean
 
Greyrider,

I'll take the worst case scenario as my benchmark,
hitting something with no give at all compared to an anthill especially as I haven't even used the PTO yet.

Thanks Dean and others,
I'll go with #2 for now.

Ant story:

A friend of mine had mites on his row of trees and someone told him to get a black anthill started. So the black ants scoured his trees and killed off all the mites.
But then he had black ants coming into the house.
An old guy, maybe the same guy said, "Get a red ant hill; they'll drive the black ants away and won't go into the house themselves. :p
 
(quoted from post at 18:45:04 07/15/16) Howse recommends 5 but I use 2 and have no shearing problems. However their bolt is 1/2 inch., Start out with 2 and if it appears to shear too easily switch to 5.

Jimmyjack,

Mine is 1/2" as well so thanks for that important factor that makes an even stronger case for #2 in my case.:)

Thanks,
Terry
 
I always use grade 2 shear bolts,
I have a cheap cutter and am sure the gearbox is not as strong as other brands

however, I keep a hand full of grade 2 bolts in the tool box, punch, hammer and other tools as necessary to drive out a sheared bolt, if it were to occur.

as others have said, price a new or rebuilt gearbox, shear bolts are cheap
just my two cents.
a231987.jpg
 
I use to have that problem then I went to Tractor supp.
they have 3 grades I use the hardest one I think its there # 3
I also use a slip clutch I never have any problems.
 
Well . . . Max,

My gearbox is a very heavy duty one but very old as well; 1980 I think. I treated it to 75W110 but may go to 75W140.

What do you think of this:
Something I picked up from a "Tractor Mike" video yesterday.
He says to use the self locking nuts and to leave it slightly shy of tight so that the rattle room will let the bolt shear easier.

Sounds logical to me and so if I found I was breaking too many 2's with the bolt loose, then the next step would be to tighten the next one to see if it would take more of a shock that way.

Thanks,
Terry
 
(quoted from post at 17:24:40 07/16/16)
At least with a slip clutch, they don't give up on you in the middle of a field. :wink:

But the shear pin method affords me the only opportunity of being outstanding in my field. :)

The deck on mine was a real dopey design so no wonder it rusted to beat the band. If they wanted the deck to hold a lake of water they couldn't have done a finer job.

If they had simply constructed it with the side and rear angle iron facing downward like across the front, the water wouldn't have pooled on it.
38095.jpg
 
(quoted from post at 19:47:13 07/16/16)
(quoted from post at 17:24:40 07/16/16)
At least with a slip clutch, they don't give up on you in the middle of a field. :wink:

But the shear pin method affords me the only opportunity of being outstanding in my field. :)

The deck on mine was a real dopey design so no wonder it rusted to beat the band. If they wanted the deck to hold a lake of water they couldn't have done a finer job.

If they had simply constructed it with the side and rear angle iron facing downward like across the front, the water wouldn't have pooled on it.
38095.jpg

Your mower is looking pretty good now. I wish mine looked that good. Actually, all mine really needs is a paint job. I had my neighbor down the road weld up three or four cracks in it. It never had any rust problems so the body metal is still good and strong and heavy. Of course the weather in California has probably helped it a lot. :wink:
 
Your mower is looking pretty good now. I wish mine looked that good. Actually, all mine really needs is a paint job. I had my neighbor down the road weld up three or four cracks in it. It never had any rust problems so the body metal is still good and strong and heavy. Of course the weather in California has probably helped it a lot. :wink:[/quote]

No doubt! Poor California up against having entities taking over water control, with detrimental intentions. I met a man last summer who just bought a house on Salt Spring. Politics . . . or should I say, "world conditions" came up and he says, "interesting that you should mention water, because the last straw that made me decide to leave California was when they started taxing me for the water in my rain barrel."

Thanks about the Mower.
I'm happy so far at how it has panned out.
Just by a hand start on the input shaft I can get it to slowly spin 360. The gears have that kind of soft cyclical chuckle when I do. Trying to think of where I've heard that gear sound in something else and whatever that, was it was a healthy unit.
Old-timers setting in.

I'm thinkin' that the Massey Ferguson people might have had a dual purpose for the arched channels on top and I underestimated them. Strength obviously but the ends weren't fixed to the side angle iron. . . probably so they'd serve as water drains at the ends.

I'll have to build a dog house
For the hog

T
 

My cutter is also able to hold water on the back deck. When I fixed a couple of rust spots and repainted it, I drilled a couple of holes so the water could run out and not re-rust it. Say that would be a good word for sweetfeet...re-rust. :lol:
 
(quoted from post at 22:56:20 07/16/16) Your mower is looking pretty good now. I wish mine looked that good. Actually, all mine really needs is a paint job. I had my neighbor down the road weld up three or four cracks in it. It never had any rust problems so the body metal is still good and strong and heavy. Of course the weather in California has probably helped it a lot. :wink:

No doubt! Poor California up against having entities taking over water control, with detrimental intentions. I met a man last summer who just bought a house on Salt Spring. Politics . . . or should I say, "world conditions" came up and he says, "interesting that you should mention water, because the last straw that made me decide to leave California was when they started taxing me for the water in my rain barrel."

Thanks about the Mower.
I'm happy so far at how it has panned out.
Just by a hand start on the input shaft I can get it to slowly spin 360. The gears have that kind of soft cyclical chuckle when I do. Trying to think of where I've heard that gear sound in something else and whatever that, was it was a healthy unit.
Old-timers setting in.

I'm thinkin' that the Massey Ferguson people might have had a dual purpose for the arched channels on top and I underestimated them. Strength obviously but the ends weren't fixed to the side angle iron. . . probably so they'd serve as water drains at the ends.

I'll have to build a dog house
For the hog

T[/quote]

Maybe they figured it was up to them to build the mower and up to you to build a barn to keep it in. :mrgreen:
 
What's a #3??? Why would you use the hardest grade for a shear bolt? The term 'shear' means it will give way when it exceeds the UTS point. When an implement hits an obstruction such as a tree root or large rock, you want the engaging part to break away from it easily without damaging more valuable parts like PTO's and hydraulic gear boxes. Thus you want the lowest grade (Grade 2) for your shear bolt/pin. TSC probably sells 2, 5, and 8 stocked. Helpful Hint: Grade 2 bolt has no line markings on the head. Grade 5 has 3 lines, and Grade 8 has 6. Click on the link for chart...


Tim
Torque Values / Bolt Grade ID
 
Tim,

Great chart!

Question:
I have quite a few ancient square headed 1/2" bolts without head markings. Will those serve as a typical #2 as well?

When did that grading system come into play and did it apply to these as well?

Thanks,
Terry
 
My Tractor Supp has 3 grades of bolts #3 is the hardest
I use a # 3 but I also use a slip clutch.
have not had any concerns
and the mower works good.
I have my slip clutch is mounted on the tractor not the mower.
 
The overrunning clutch mounts to the tractor PTO shaft, and is the connection to the rotary implement. It has a shear bolt to PROTECT THE TRACTOR PTO, not the other way around. The chart is just listed here under 'TORQUE VALUES' -look over to the left side of this page, under Research & Info. I rarely go to TSC so never looked at their grading codes, still silly what 1,2, and 3 mean. I learned years ago they never have what I need anyway so I don't waste my time...If by '3' the bolt head has three lines, then it is a Grade 5, which is fine too for a shear bolt but I wouldn't go much harder. The key is for the bolt to fail, thus saving you from damaging your PTO or worse...

Tim *PloughNman* Daley(MI)
 

i used to mow with a 5 foot king kutter on my WD. the WD has an oddball PTO setup - i assume it's farmerized. it has a two piece PTO shaft, and the 2 pieces are connected by a heavy pipe sleeve with a bolt at each end.the hole in the PTO shaft coming out of the tractor is 1/2" - but the hole for the rear shaft is 5/16".

for that bolt, i used a grade 8, since i had a big supply of them on hand - and i sheared that grade 8 bolt on a regular basis - a few times each mowing season.

i now mow with my 2N, which of course has a single piece PTO shaft, so now i rely on the 1/2" bolt just in front of the mower's gearbox. however, in 3 years of mowing with the N, i've only broken that bolt once. methinks i'll be better off replacing it with a softer bolt - that one's a grade five at the moment. gonna switch to a grade two.

as a side note, i'd never know i'd broken one of those 5/16" bolts till i engaged the PTO and the mower ignored it. when i sheared the half inch bolt, it sounded like someone just fired a 30-06. that makes me think i'd probably be better off with a softer bolt that would shear with less drama ;)
 
(quoted from post at 12:25:25 07/18/16)
i used to mow with a 5 foot king kutter on my WD. the WD has an oddball PTO setup - i assume it's farmerized. it has a two piece PTO shaft, and the 2 pieces are connected by a heavy pipe sleeve with a bolt at each end.the hole in the PTO shaft coming out of the tractor is 1/2" - but the hole for the rear shaft is 5/16".

for that bolt, i used a grade 8, since i had a big supply of them on hand - and i sheared that grade 8 bolt on a regular basis - a few times each mowing season.

i now mow with my 2N, which of course has a single piece PTO shaft, so now i rely on the 1/2" bolt just in front of the mower's gearbox. however, in 3 years of mowing with the N, i've only broken that bolt once. methinks i'll be better off replacing it with a softer bolt - that one's a grade five at the moment. gonna switch to a grade two.

as a side note, i'd never know i'd broken one of those 5/16" bolts till i engaged the PTO and the mower ignored it. when i sheared the half inch bolt, it sounded like someone just fired a 30-06. that makes me think i'd probably be better off with a softer bolt that would shear with less drama ;)

The only problem I have with shear bolts is you never know if they are really protecting anything until one breaks, then you hope nothing else also broke.

At least with a slip clutch you can mark it and see if it moves and is doing it's job. If you don't think it's moving, you can always loosen the nuts on the springs a bit until it starts to slip too much and then re tighten them a little until it no longer slips.

Best of both worlds would be to have a slip clutch and a shear bolt.
 


[b:3c7c770a74]Best of both worlds would be to have a slip clutch and a shear bolt.[/b:3c7c770a74]

can't argue with this reasoning. i think i'm ok with just the shear bolt on the finish mower, but i'll be looking into rehabbing the slip clutch on the brush hog.
 
(quoted from post at 13:02:39 07/18/16)

[b:51f9061050]Best of both worlds would be to have a slip clutch and a shear bolt.[/b:51f9061050]

can't argue with this reasoning. i think i'm ok with just the shear bolt on the finish mower, but i'll be looking into rehabbing the slip clutch on the brush hog.

All it takes is a wire brush in a drill motor and maybe a couple new clutch discs.
 

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