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Clutch verses sheer pin on rotary cutter

3046 Views 29 Replies 10 Participants Last post by  letmgrow
What is better ? Sheer pin or a slip clutch and why?. I’m looking to buy a 48 in rotary cutter.
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Both. If one fails, maybe the other will save you some damage.
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I am a Tractor Mike fan.
Great video. I learned some good stuff.
I’m thinking about picking up a used frontier rotary cutter. It hasn’t been used very much. It is still all green, and not rusty. It’s dusty from being in a barn. The owner says he only used it a few times. It is a sheer pin model.
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I like a shear pin. Through use & time, a slip clutch can rust/seize up and fail to "slip". The gears in your gearbox now become the weakest point! A shear pin always has need the same force to break. Bob
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Both if possible, Shear Pin otherwise, IF the correct Shear Pin is used and NOT UPGRADED it will always work. Rust and miss adjustment on the clutch will not guarantee the gear box or PTO will live a long happy life. Just keep the correct shear pins on the machine and the correct wrenches handy. Cheap wrenches are great for this.
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Have had shear bolts on both cutters. Work fine.
I like the bolt myself. 5 minutes to repair if needed.
I have a locked clutch on my rototiller. Im not looking forward to spending about an hour on maintenance to get it back in shape. Its supposed to be a yearly pm from what i hear.
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'I have a slip clutch on my RT 1170 tiller and haven't had to touch it since I first bought the tiller in 2007. I use it every spring and late summer with no issues at all.
I do store it inside which may make a difference. The same is true of my GM 1190 grooming mower except that I use it much more often.
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I like a shear pin. Through use & time, a slip clutch can rust/seize up and fail to "slip". The gears in your gearbox now become the weakest point! A shear pin always has need the same force to break. Bob
Thanks for all the advice. I ended up buying the used Frontier rc2048. Seems to be good. I hooked it up and tried it out yesterday. I first greased all the u joints, and the rear wheel zerk. The unit has been sitting for some time in a barn. It was really dusty, and looks like the chickens had been hanging out on it! Lol

it’s funny how 3 different dealers all said that they only sell cutters with the slip clutch. They all told me they were better. Must be better for their service and parts dept.
anyways, the cutter works good, I did notice that the blades can get off kilter upon start- up if you aren’t easy on increasing rpm . It has done it 2 times. I suspect it’s just because it’s sat for a while and the blades didn’t swing out all the way. After using it for a bit they seem fine. Nice and smooth. I lifted it up and can’t feel any slop in the big round mounting head or the blades where they pivot. That first start up was a little rough!!
I started it at a very low idle, but they got off balance.
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I do know the slip clutch is operable on my tiller. Last year I tilled up a new plot and got into some deeply rooted grape vines and tested the slip clutch several times. If there was any rust buildup is certainly gone now. I don't worry about the mower. It's a mower, not a brush cutter and I keep the areas where I use the mower mowed often so there is no chance I'm going to have to engage a slip clutch.
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I’m going to keep this area mowed down too. After a few high spots I excavated yesterday, it should be pretty easy on it! Lol I’ve done most of the big cutting already. I bought this because it’s just too rough to run a mid mount mower, or use my zero turn. It gets kinda wet in there too. It’s along a creek.
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Thanks for all the advice. I ended up buying the used Frontier rc2048. Seems to be good. I hooked it up and tried it out yesterday. I first greased all the u joints, and the rear wheel zerk. The unit has been sitting for some time in a barn. It was really dusty, and looks like the chickens had been hanging out on it! Lol

it’s funny how 3 different dealers all said that they only sell cutters with the slip clutch. They all told me they were better. Must be better for their service and parts dept.
anyways, the cutter works good, I did notice that the blades can get off kilter upon start- up if you aren’t easy on increasing rpm . It has done it 2 times. I suspect it’s just because it’s sat for a while and the blades didn’t swing out all the way. After using it for a bit they seem fine. Nice and smooth. I lifted it up and can’t feel any slop in the big round mounting head or the blades where they pivot. That first start up was a little rough!!
I started it at a very low idle, but they got off balance.
That's common for any mower with swinging blades. Anytime you stop the mower the blades can move into a position which throws the mower out of balance until you engage the gearbox and the blades start turning. I never engage the gearbox with the engine above an idle and then I ease the PTO lever into the run position. Once you speed the engine up the blades will swing out and everything will run smoothly as long as there isn't a chunk of steel missing on one of the blades. It doesn't hurt to peek under the mower once in a while and have a look at the blades and check for a gearbox seal leak.
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That's common for any mower with swinging blades. Anytime you stop the mower the blades can move into a position which throws the mower out of balance until you engage the gearbox and the blades start turning. I never engage the gearbox with the engine above an idle and then I ease the PTO lever into the run position. Once you speed the engine up the blades will swing out and everything will run smoothly as long as there isn't a chunk of steel missing on one of the blades. It doesn't hurt to peek under the mower once in a while and have a look at the blades and check for a gearbox seal leak.
No leaked. Fluid is full. Blades have very minimal wear. Few small nicks. Nothing too crazy. They guy I bought it from did use a few sheer pines. He handed me a package of them with 4 missing. So at least 5 sheer pins. All in all everything looks pretty good though
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No leaked. Fluid is full. Blades have very minimal wear. Few small nicks. Nothing too crazy. They guy I bought it from did use a few sheer pines. He handed me a package of them with 4 missing. So at least 5 sheer pins. All in all everything looks pretty good though
One other quick piece of advice. You will find a vent either on top or near the top of the gearbox. It's not a bad idea to unscrew the vent and rinse it out in parts cleaner and blow it out with compressed air. These vents can get plugged over time and when the gearbox lube gets hot (and it will) the gearbox can't vent and lube may pass by the shaft seal or even blow it out and all the lube will leak out without you even knowing it until the gearbox seizes and the driveline stops turning.
This hold true for any piece of equipment with a gearbox on it.
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'I have a slip clutch on my RT 1170 tiller and haven't had to touch it since I first bought the tiller in 2007. I use it every spring and late summer with no issues at all.
I do store it inside which may make a difference. The same is true of my GM 1190 grooming mower except that I use it much more often.
If you didn't see smoke from your tiller slip clutch or have SC marked to determine slippage I will BET A $1 to a doughnut hole that your tiller slip & grooming mower SC's are stuck. I agree storing inside is better but it would be in your financial interest to loosen,slip re-adjust your implements slip clutches once a year.

Most equipment operators manuals I've read recommend at the beginning of each use season to loosen,then slip SC components to free any stuck plates then adjusting to spec's. Most equipment operators don't follow these instructions & if there's some type of failure blame it on the tractor &/or equipment. I know because I was employed at a JD dealership for over 21 yrs having served 13 of those yrs as the dealer service manager
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A quick note on shear pins...well 2!
1. ALWAYS replace broken shear pins with the same grade. I'm thinking yours ae Gr 5 (3 lines on the bolt head). Gr 2 (no lines) are to soft and tend to bend or smear rather than shear. Gr 8 (6 lines) is just plain too hard and you may break something else before the shear bolt!
2. Do NOT tighten! Shear bolts always have a self-locking nut on them. When properly installed, you should be able to rotate the bolt or nut by finger pressure with only a SLIGHT drag. Locking the bolt tight draws the 2 plates together and creates friction between the plates. The friction now has to be overcome for the shear bolt to shear.
Bob
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If you didn't see smoke from your tiller slip clutch or have SC marked to determine slippage I will BET A $1 to a doughnut hole that your tiller slip & grooming mower SC's are stuck. I agree storing inside is better but it would be in your financial interest to loosen,slip re-adjust your implements slip clutches once a year.

Most equipment operators manuals I've read recommend at the beginning of each use season to loosen,then slip SC components to free any stuck plates then adjusting to spec's. Most equipment operators don't follow these instructions & if there's some type of failure blame it on the tractor &/or equipment. I know because I was employed at a JD dealership for over 21 yrs having served 13 of those yrs as the dealer service manager
Thanks for the advice. After spending 59 years in the auto repair industry, 36 of those owning and operating an auto repair center before semi retiring and still owning an automotive machine shop I can assure you after rebuilding and repairing automatic transmissios, transaxles, transfer cases, standard transmissions and differentials I have a little knowledge about how a slip clutch works and if it is or isn't working.
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