Rotary cutter, slip clutch or shear pin??

[hydrovane218]

I just bought a 5' Howse new yesterday, having never used one or looked into them much before. This has a 1/2" shear bolt in it and it surprised me me how much it took to break. It went over 2 & 3" trees fine and even a 4" that I would normally cut with a saw. The kicker was the rock the size of a small bowling ball and my slow reaction time as the cutting area was relatively clear of them up until then. By the sounds of the required maintenance on a slip clutch, I would say the shear bolt setup is better for my needs and likely yours as well.

 

[sweettractors]

I just bought a 5' Howse new yesterday, having never used one or looked into them much before. This has a 1/2" shear bolt in it and it surprised me me how much it took to break. It went over 2 & 3" trees fine and even a 4" that I would normally cut with a saw. The kicker was the rock the size of a small bowling ball and my slow reaction time as the cutting area was relatively clear of them up until then. By the sounds of the required maintenance on a slip clutch, I would say the shear bolt setup is better for my needs and likely yours as well.

Have you checked the grade of the shear bolt in the new Howse cutter? Ken Sweet

 

[Baby Grand]

Have you checked the grade of the shear bolt in the new Howse cutter? Ken Sweet

That's a good idea - I would think a 4" tree or a bowling ball sized rock should shear the right size & grade of bolt. Otherwise, the weakest link in the chain may be in your tranny.

 

[greg_g]

I would think a 4" tree or a bowling ball sized rock should shear the right size & grade of bolt.

Not necessarily. What breaks shear bolts is torque. Instantaneous torque doesn't always do it, usually the hinged blade design prevents all the shock from reaching the shear bolt. But prolonged torque will. Example; I once owned an IM500 (shear bolt rotary cutter) which would literally shred 3" saplings and knock chunks outa the blade edges on skull sized rocks. During the entire time I owned it, I broke exactly one shear bolt. And that was while cutting a walking path through an overgrown woodlot where the neighbors kept their horses. I mowed over a discarded saddle blanket !!! Bogged down the engine before snapping the shear bolt like a twig.

//greg//

 

[sweettractors]

Not necessarily. What breaks shear bolts is torque. Instantaneous torque doesn't always do it, usually the hinged blade design prevents all the shock from reaching the shear bolt. But prolonged torque will. Example; I once owned an IM500 (shear bolt rotary cutter) which would literally shred 3" saplings and knock chunks outa the blade edges on skull sized rocks. During the entire time I owned it, I broke exactly one shear bolt. And that was while cutting a walking path through an overgrown woodlot where the neighbors kept their horses. I mowed over a discarded saddle blanket !!! Bogged down the engine before snapping the shear bolt like a twig.

//greg//

WE still sell those same cutters under the Hawkline name. They are about bullet proof. Ken Sweet

 

[greg_g]

Concur. The only reason I don't have that IM500 anymore, is that I upgraded to an IM602 ( six foot w/slip clutch for those that don't know model numbers). Better yet.

//greg//

 

[hydrovane218]

The bolt was a grade 5(3 marks on the head). I would have thought it should have even been weaker than that to save the gearbox but not being familiar with these, I went with what was in it.

 

[sweettractors]

The bolt was a grade 5(3 marks on the head). I would have thought it should have even been weaker than that to save the gearbox but not being familiar with these, I went with what was in it.

Who ever assembled and sold that cutter to you, did not want to be bothered by calls about grade 3 pins shearing. They had rather sell you driveline or gearbox parts. Ken Sweet

 

[MESSMAKER]

I only shear about one bolt every 50-75 hours of use. It takes maybe 5 min. to replace. I cut some decent sized stuff and hit rocks as well. I think a slip clutch could be more time,trouble and $$ than they are worth.

 

[picker77]

I'm with the shear bolt crowd, for sure. I've run a 5' Rhino since 1996 and have replaced exactly ONE shear bolt. Admittedly, I don't mow a lot of rough stuff and we don't have rocks in the pastures, but the several times I've turned around and backed into some hedgerows and tree lines it cut everything in sight and didn't break the shear bolt. I do keep spare bolts handy, but haven't had to use one in about 5 years. No hassle, no adjustments, no maintenance, no problems. Unless you mow a lot in unknown territory or down in the woods in the really rough stuff, a driveline clutch just seems like more trouble than it's worth.