Help Broken Shear Pin

[Bob77064]

Ran the bush hog ( mdern ag ) 5' cutter for a short time. The shear pin broke. The top of the bolt ( pin ) says 307A and JG. IS this a common part and how hard is it to change?

 

[phiferpharm]

I'm guessing this is the Bolt that attaches your drive shaft to the gear box on top of your bush hog. I use low grade bolts from the hardware store and have had no problems with them. I guess I will pop one every couple of hours of use, especially when I'm in a new area of the property. Takes maybe 5 minutes to change.

 

[strum456]

It sounds like your bolt is metric, based on the letters on the head. A standard bolt will have lines. 3 lines = grade5 5 lines= grade 8 (just to name a couple). Anyway, get the correct size bolt and you should be good to go. Make sure the bolt isn't threaded where it goes through the yoke and shaft or it will wear the hole goose egg shaped.

 

[tcreeley]

Softer bolt has fewer lines. Softest bolts have no lines.

 

[strum456]

Count your lines, add two and that's the hardness grade. This only applies to standard bolts. Metric will have a number, like 8.8.

 

[Bob77064]

Thanks for the help everyone.

 

[Mark Page]

A large pin punch/drift will make it easy to drive the old bolt out. If need be you can drill it out, but should be a last resort.

 

[wcampbell47]

Reading this makes me want a shredder with a slip clutch!

 

[Bob77064]

Thanks Mark & WC, this makes me wonder if I should have gotten a model with a slip clutch. But I have been told me that if you don't use the cutter with the slip clutch enough that the slip clutch can rust together.

 

[wcampbell47]

Thanks Mark & WC, this makes me wonder if I should have gotten a model with a slip clutch. But I have been told me that if you don't use the cutter with the slip clutch enough that the slip clutch can rust together.

Recently read a thread on servicing the slip clutch at the beginning of the season to cure just that ill. Something like loosen all the bolts then from the tractor engage the pto in order to break it loose. Need to find and re-read as I need to service the slip clutch on my tiller.

 

[SPYDERLK]

Softer bolt has fewer lines. Softest bolts have no lines.

Pretty true. No lines is considered Gr2. 307A is softer than grade 2 Bound to be a nuisance as a shear bolt. Grade 5 is often substituted to make the implement useful. ... Slip clutch even better.
larry

 

[Short Game]

How hard is changing out the shear bolt? Glad I don't have a slip clutch on my hog. Something else to deal with. I often prefer the old technology.

 

[jshwhite]

I much prefer shear bolts. My bh has a slip clutch and shear bolt. I keep the slip clutch tight and just let the shear take it if I hit something. I keep some extras on hand in the shop. I just get some regular bolts from hardware. As mentioned previously, be sure the bolt is long enough to not have the threaded part in the hole otherwise it will wear the hole out. To change it just line it up, knock the piece out with a punch, and put a new one in. Also, don't tighten the nut down too much. It needs to be a bit loose to shear properly.

 

[Bob77064]

I much prefer shear bolts. My bh has a slip clutch and shear bolt. I keep the slip clutch tight and just let the shear take it if I hit something. I keep some extras on hand in the shop. I just get some regular bolts from hardware. As mentioned previously, be sure the bolt is long enough to not have the threaded part in the hole otherwise it will wear the hole out. To change it just line it up, knock the piece out with a punch, and put a new one in. Also, don't tighten the nut down too much. It needs to be a bit loose to shear properly.

Thanks for your help When I line it up do I need to disconect the PTO to turn the shaft on the bush hog?

 

[jshwhite]

Thanks for your help When I line it up do I need to disconect the PTO to turn the shaft on the bush hog?

Are you asking about disconnecting from the tractor? You don't need to if you have live pto - should spin freely. The best way to line it up is to just block or have someone hold the bush hog blades so it doesn't turn the bush hog shaft when you are rotating the pto shaft. Or just rotate it with quick little jerks until you get it lined up.

I have seen the shaft slide a bit to the front or back on the bush hog shaft, so just be aware of that.

Hope this helps. It's easy. Once you've done it a couple of times, it'll be old hat

 

[Bob77064]

Are you asking about disconnecting from the tractor? You don't need to if you have live pto - should spin freely. The best way to line it up is to just block or have someone hold the bush hog blades so it doesn't turn the bush hog shaft when you are rotating the pto shaft. Or just rotate it with quick little jerks until you get it lined up.

I have seen the shaft slide a bit to the front or back on the bush hog shaft, so just be aware of that.

Hope this helps. It's easy. Once you've done it a couple of times, it'll be old hat

My tractor has an independent PTO, it does not seem to spin freely.

 

[jshwhite]

Interesting...perhaps you do have to pull the shaft off the tractor - that's a pain. I'm not too familiar with the differences in the types of pto - maybe someone else on here can chime in.

 

[Bob77064]

Thank you for your help js. If not I can remove the plastic shield and get to it.

 

[Short Game]

My LS R4010 has some kind of brake on the PTO, protecting me from myself. I hate it. My old Cub Cadet 4274 (Mitsubishi) spins freely when disengaged.

 

[Mechanos]

My JD955 has a PTO break as well. I just shift the PTO lever to Mid PTO and that disengages the rear PTO so I can turn the shaft by hand.