9ft Topper shear bolt

briaineo

Hi

picked up an old topper last week, there wasn’t a brand on it the owner thought it was made by Laois machinery or a company in Laois not 100% sure which he said now.

it red so maybe it’s a hispec

has three blades and is run by two belts which I replaced. It works fine but it doesn’t have a shear bolt as far as I can tell.

since it’s driven by belts would you think I need to get a pto shaft with a shear bolt? Or would the belts just slip if I was to hit a large stone or something?

kk.man

Hi spec is a Carlow company. They made Toppers years back now is all slurry tankers etc.

Is it red in colour or probably slightly orange and is it trail type?

briaineo

It’s quite red, trailed on skids not side mounted.

kk.man

https://www.boards.ie/discussion/comment/119299857#Comment_119299857

Yeah nearly certain it's a hi spec from bagenalstown. Very few left now...I can't answer your question tbh. A neighbour had one for years. I'd say have the shear bolt in the PTO it be the safest.

kevthegaff

One hear is breaking shearbolts engaging but working perfect of I stick in an old Alan key. Someone was saying to drill a bigger hole for a larger shearbolt..

cjpm

https://www.boards.ie/discussion/comment/119301023#Comment_119301023

You don’t have a soft start option for the PTO Kev? To reduce the shock when it starts up?

kevthegaff

https://www.boards.ie/discussion/comment/119301325#Comment_119301325

Maybe the tm155 is too big for it!

cjpm

https://www.boards.ie/discussion/comment/119301334#Comment_119301334

Jeez I would have been sure a relatively modern tractor like a TM would have it…. Maybe someone else knows??

kevthegaff

Is it the button beside the pull up switch?

FintanMcluskey

https://www.boards.ie/discussion/comment/119301528#Comment_119301528

Yes.

PTO comes on slowly then

kevthegaff

Mustn't be working...

J.O. Farmer

Try a different brand of shearbolt.

I had a bag of co-op own brand shear bolts and couldn't keep them in the topper.

Some would break on start up as soon as I started to rev the tractor, more would go as soon as I hit light rushes.

I tried sparex shearbolts and it worked away perfectly.

MfMan

Breaking shearbolts upon start-up is a constant pain for me. Try to keep the PTO shaft straight and level behind tractor upon startup and only offset it after revving. I also usually start in Eco 540 mode first which seems to take the 'sting' out of it and switch over then immediately.

hopeso

https://www.boards.ie/discussion/comment/119308601#Comment_119308601

Would you not be using 540E for the topper anyway?

kevthegaff

I try all those things, I just got normal bolts from a hardware. Are they weaker than shearbolts

Donald Trump

https://www.boards.ie/discussion/comment/119301023#Comment_119301023

I'd prefer to just have a bag of shearbolts ready even if it eats through a few of them. Unless you know for sure that you are never going to encounter anything unexpected!

MfMan

https://www.boards.ie/discussion/comment/119308746#Comment_119308746

Not in the habit of it - is it any advantage? Unused to these new-fangled developments!

hopeso

https://www.boards.ie/discussion/comment/119309315#Comment_119309315

There’s a huge advantage, especially now with the price of diesel. Your tractor will be only doing around 1600 engine rpm to give you 540rpm at the shaft in 540E, while it will need over 2000 engine rpm to give 540 rpm at the shaft the other way. For machines that don’t need a lot of power, like toppers, fert shakers, sprayers, vacuum tankers etc, 540E should always be used.

Bass Reeves

https://www.boards.ie/discussion/comment/119308913#Comment_119308913

Bolts have three grades of strength you see it stamped on them

8.8 these are the normal silver bolts you buy in a co-op.

10.9 is usually the optimum strength for shear bolts.

12.9 is the third strength rating.

The 10.9 and 12.9 are usually black in colour.

On shear bolts you can use the 8.8 nylon lock nuts rather than the two solution

Always tighten the lock nut but do not squeeze.

Lots of lads do not know but if replacing nuts on towbars, or on points on the back of a tractor always check the strength.

I am very lucky in Limerick there is a place called Hasset Nut and bolt. They are online as well. You get virtually anything in a nut or bolt with any head on it

FintanMcluskey

https://www.boards.ie/discussion/comment/119311346#Comment_119311346

The rest of the equipment is fine but topping is an odd task in itself. Its a job thats incredibly variable.

You could be topping the best of pasture or the roughest bottoms.

In rough spots, shock loading the tractors 540E PTO driveline with a topper could offset the fuel savings fairly fast!

FintanMcluskey

https://www.boards.ie/discussion/comment/119311383#Comment_119311383

10.9 is usually the optimum strength for shear bolts.

🤔 just because they never break doesn't mean they are optimum Bass.

10.9 bolts have such high tensile strength they offer little to no sacrificial protection for the driveline.

8.8 is usually the standard for most grass equipment

White Clover

https://www.boards.ie/discussion/comment/119311410#Comment_119311410

I was just about to say that! 540e grand for knocking the top off of wispy grass but making a topper growl going through heavy rushes wouldn't be long eliminating the 540e gear from most tractors.

DBK1

https://www.boards.ie/discussion/comment/119311383#Comment_119311383

10.9 would certainly not be optimum for a shear bolt, 8.8 is what should be used. Too strong a shear bolt could end up being a very expensive repair job.

Edit to add: just seen Fintan’s post so that’s already covered.

Bass Reeves

https://www.boards.ie/discussion/comment/119311536#Comment_119311536

https://www.boards.ie/discussion/comment/119311559#Comment_119311559

10.9 is the optimum for shear bolts and they do break.

Anto_Meath

There is a agri spot beside me that would sell a lot of spurious parts for tractors, passing one day & bought a box of shear bolts for the topper.. they broke my heart I would have been better of with a twig from the hedge. Was in a main dealers a few weeks later bought a box there. Topped some right heavy rushes in a wet field with them & didn't change 1. They were twice the price but would have been value even at 10 times the price.

Bass Reeves

https://www.boards.ie/discussion/comment/119311680#Comment_119311680

What grade are they look at the top of the nut.

whelan2

https://www.boards.ie/discussion/comment/119311680#Comment_119311680

I didn't change one shear bolt last year. Then first run in this year noticed a funny noise, stopped immediately. Shaft itself broke. Had to buy a new shaft and have smaller shear bolts in it . Have broke 3 or 4 bolts since.

cjpm

https://www.boards.ie/discussion/comment/119311536#Comment_119311536

A 10.9 bolt is approximately 20% stronger than an 8.8. If you’re breaking 8.8s easily on start up maybe then you could consider a 10.9.

BUT if it’s a 5.8 or a cheap bolt with no grade stamped on it, don’t jump straight to 10.9 as 8.8 is probably good enough for the job.

emaherx

https://www.boards.ie/discussion/comment/119311633#Comment_119311633

The optimum shear bolt is the one specified in the manual by the manufacturer, it can vary by machine.

Having said that I use 8.8's in my topper and no idea what's in the manual. I very rarely break a bolt, no soft start on my PTO so just start in low revs and increase power slowly.

kevthegaff

Is 12.9 stronger than 10.8

cjpm

https://www.boards.ie/discussion/comment/119312404#Comment_119312404

About another 20% stronger

kevthegaff

I'll go for that one!

whelan2

No revs and engage pto very very slowly here

kevthegaff

https://www.boards.ie/discussion/comment/119312442#Comment_119312442

Not working for some reason

Bass Reeves

https://www.boards.ie/discussion/comment/119312432#Comment_119312432

12.9 is too strong. 10.8 is normal shear bolt strength.

A few of the co-op for some stupid reason started packaging 8.8 bolts 10-15 years ago as shear bolts. 8.8 have have very low tensile strength. They are basically used to bolt something together that will come under very little pressure.

Bolts are graded to three characteristics, Proof load, yield and tensile strength. The PL is the load at which a bolt should not deform, it's about 60% of its TS. YS is the strength at which if a bolt comes under it will not return to its original characteristics. The TS is the strength a bolt will shear at.

However if a bolt is constantly put above its PL it's TS will decrease ( basically it's diameter gets narrower or it gets damaged) .

You might use an 8.8 rated bolt as a shear bolt on something like a fertlizer spreader. However in mower, toppers you always use 10.9 bolts. There YS is about the same as the TS of a 8.8 bolt and there PL would be 20% below that.

Cavanjack

I’m topping with a disk mower near 30 years and have yet to break a shear bolt. Rough lads/lassies the lot of you!!!

FintanMcluskey

https://www.boards.ie/discussion/comment/119312679#Comment_119312679

However in mower, toppers you always use 10.9 bolts.

May as well use a haybob tine instead or weld the shaft soild

https://www.boards.ie/discussion/comment/119312750#Comment_119312750

If your using 10.9s you won't break many 😅