Bush Hog - shear pin or slip clutch

CMV · May 6, 2018

Will be getting a new BH brand rotary cutter. Light duty, 6', BH6 model. I initially asked for slip clutch, but am now 2nd guessing myself. Not a drastic price difference.

My 5' TSC current one has been a champ and kept on trucking thru a lot of stuff well over it's 1" cut rating, softball sized rocks, concrete blocks - just seems to destroy anything the tractor can push over and not care. Never broke a shear pin. And now my trail thru the woods is over 3/4 complete, the big rocks have been removed, and I can just set the cutter pretty low and basically finish mow with it.

SO going up to a 6' with upcoming new machine purchase, does it make sense to go with slip clutch vs shear pin style? I think the light duty BH ones are otherwise the same besides that one difference. Only reason I'm wondering about my choice now is the tiller thread in another section about the slip clutch adjustment and maintenance. Has me wondering if I'm not being inconvenienced replacing shear pins today, and I would assume Bush Hog brand is at least as tough as TSC County Line, am I just adding complexity for no value?

shui5612 · May 6, 2018

I see no problems with shear pins. But the bigger you go, whether a snow blower or a mower, the higher the odds that a pin will shear.

I have yet to see a piece of equipment have different sized shear pins (I.e. all 4-9ft mowers I've seen use the aprox 1/4 inch size shear pins) so it's logical that going up in size essentially increases the chances of it snapping (higher load or HP).

Slip clutches are more maintenance but you get to keep going after hitting something instead of stopping and going in to replace the sheared pin..

I only have one piece of equipment with a slip clutch (Harley rake) and the rest is on shears...

My 7ft snow blower goes through shear pins easy. If there's some medium to heavy snow I might go through a couple shear pins in one sitting (about 2.5hours of snow blowing which results in either 0 or 4 shear pins).

Oldoak · May 6, 2018

My 5' HD rotory brush cutter uses 7/16" dia. shear pins. Actually called out 7/16" grade 3 bolts and a nylock nut for shear pins. Purchased it new, but it's so old the decals are long gone and I don't remember the brand.

kthompson · May 6, 2018

My cutter has slip clutch and I have had no issue with it. Maybe I think the clutch is fine and it stuck but don't think so. Once in while it will slip but cutter is over twenty years old and has really required little adjustment to it. Then for much of that time it was stored under shelter.

My thought, here clutch seems to be the most popular but on the very light weight think many have shear pin. My guess is cost and weight savings. To me if you have mowing that is as you described it will be basically doing finish mowing you may want the shear pin for it should not be needing to replace very often and not worry about maintenance of the slip clutch.

mddorange · May 7, 2018

I have a slip-clutch on my medium duty cutter and the only problem I have had in all these years is the disks rusting a little in the winter law-off.

Oldoak · May 7, 2018

mddorange said:
I have a slip-clutch on my medium duty cutter and the only problem I have had in all these years is the disks rusting a little in the winter law-off.

That is why the instructions that came with my Land Pride tiller describe a procedure to loosen the clutch pack and slip the disks before using the tiller when it has sat for an extended period of time. I have do that once a year, every Spring and never had a problem for 12 years.

mddorange · May 7, 2018

Oldoak said:
That is why the instructions that came with my Land Pride tiller describe a procedure to loosen the clutch pack and slip the disks before using the tiller when it has sat for an extended period of time. I have do that once a year, every Spring and never had a problem for 12 years.

When I was doing exactly what my LP manual called for is how I found that the disks had rusted enough for them NOT to slip any. That is when I took them apart and cleaned the rust off.

EddieWalker · May 7, 2018

My Landpride 6 foot rotary cutter was originally a sheer bolt. I have a 35 hp tractor, and that's borderline at being big enough for it. More power and weight would be nice, but it is what it is. I've broken more sheer pins then I can count. Some days I've gone through two or three of them. I always carried half a dozen in my tool box. Then one day when I got stuck really bad, I bent my driveshaft to the mower and I had to buy a new one. While buying the drive shaft, I also got a slip clutch, and life just got a whole bunch better!!! Now, I would never own a rotary cutter without a slip clutch.

CobyRupert · May 7, 2018

As noted on another thread
Not sure what the proper method is to slip the disks, but..
I use to loosen the slip clutch bolts, mark the disks, rev the tractor & pop the PTO clutch, shut it all down, then verify that the marks show the disks had slipped, but it seems much easier to just loosen the bolts, turn the pto on, with the tractor OFF (pto is locked), and just turn the blades by hand while verifying the pto shaft is not turning.

BufordBoone · May 7, 2018

Being in the middle of a slip clutch repair, I'll add that I don't mind the annual maintenance.

I have done it, with success, on most of mine. I never had any luck on the (1993) Bush Hog that came with my farm. Purchasing a new tractor really made me want to get the older cutter right before risking a costly repair.

I have slip clutches on three mowers, a stump grinder and a wood chipper. The annual maintenance takes about 20 minutes per clutch.

I think the field time saved is worth the annual maintenance. Besides, replacing a shear bolt in 95 degree/100% humidity with no shade is not a lot of fun.