9ft Topper shear bolt

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..

Maybe the tm155 is too big for it!

Is it the button beside the pull up switch?

Mustn't be working...

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.

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

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

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

🤔 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

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.

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.

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.

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.

About another 20% stronger