Shear Pin

[Sherminator]

Ok here is an issue I know nothing about. My new brush hog, Mihindra, is shearing the pin on start up. I can turn it by hand and the cutter spins free. Three pins later same issue. As soon as the PTO engages, there goes the pin. Started with low RPMs, mid range and also with the cutter off the ground. Then ran out of bolts. Seems like the sudden "jerk" when the PTO engages is too much for the shear bolt. Am I doing something wrong? Do I need different shear bolts or should I have gotten the clutch style <This item is too late> Also the machine is a R 4041H

Thanks,

I'll post some pics since they appear to be MANDATORY. Or is it just a right of passage to be an new owner?

 

[murphy1244]

Ok here is an issue I know nothing about. My new brush hog, Mihindra, is shearing the pin on start up. I can turn it by hand and the cutter spins free. Three pins later same issue. As soon as the PTO engages, there goes the pin. Started with low RPMs, mid range and also with the cutter off the ground. Then ran out of bolts. Seems like the sudden "jerk" when the PTO engages is too much for the shear bolt. Am I doing something wrong? Do I need different shear bolts or should I have gotten the clutch style <This item is too late> Also the machine is a R 4041H

Thanks,

I'll post some pics since they appear to be MANDATORY. Or is it just a right of passage to be an new owner?

Go up a grade or two on the bolts and yes pics are manadamntory or your post self destruct

 

[kpbeddin]

It sounds to me like you are doing everything right. If it shears a pin on startup, it is bound to do the same under any kind of load. When you say you can turn it by hand, I assume everything is hooked up at that point, correct?

 

[tmeadows]

set RPM's at an idle, brush hog should be off the ground but not high enough to put pto shaft in a bind. also make sure you do have the correct size shear pins. If you go with a bolt that is too hard then you are defeating the purpose.

 

[big lar]

Double check with your dealer or the owners manual to find out the correct grade of shear bolts needed, as mentioned by others. But dont'go too high a grade- you won't break a shear bolt but a shaft instead - don't ask me how I know.

 

[Soundguy]

is that one of them mahindra that has the electric servo pto setup. .. if so.. you will need to kick in at minimum operating rpm

 

[Sherminator]

Hey guys thanks for the advise. Spoke with the dealer and he said they always side on caution, hence the grade 2 bolt. He suggested a grade 5 bolt (3 marks on top). Couple of old farmers I know said the grade 5 bolt will solve my problems and also protect the equipment as required. Coon *** father in law said "weld it tight and fixs what breaks later". He's a hellava cook but I'm not taking his advise here.

 

[Gary Fowler]

My brother in laws NH does the same thing and sometimes they will shear for no reason when mowing in light cover. I think that is because the partially sheared when engaging the electro-servo mechanism. You have to really idle it down so it is just high enough to keep from killing the engine when it engages. I dont know why they dont make those so you can feather it in with the clutch. He went to a grade 5 x 1/2" bolt and it helped but he still has to carry a supply of them when he mows. I told him if it were mine, I would drill it out to a 5/8 diameter bolt. The Howse 6 foot BH that I recently sold with my Yanmar 4220D tractor never sheared a pin in 3 years of operation and I cut large trees that would stall the engine. The drive line and gear was rated 65 HP and tractor only put out 45 so wasnt much danger of damaging the BH.