Slip clutch - shear pin ?

[Citydude]

For about ten years I had a sheer bolt on my 6ft Landpride rotary cutter. I carried several spares in my tool box and on some days, would use them all up. I'm brutal on my mower and if I can run it over, I'm going to try to cut it down. I've replaced the drive shaft a couple times now and just this year decided to try a slip clutch. I ordered it from Messicks.com and forget the price. It was more then the regular drive shaft, but I figured if it meant less time replace sheer pins, then it would be worth the cost. After putting about 20 hours or so on it, I am very impressed!! I love how it will slip a little, but then grip again and keep on cutting. That little big of slippage has made a huge difference in how much I can get done while out mowing. I just wish I had bought one sooner. Eddie

Geez Louise Eddie, you would be a good candidate to field test rotary cutters!!

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[Dave M7040]

If you have an implement with a long pto shaft, say 6 feet, then a slip clutch which shortens the pto shaft link by 6" is not going to change the pto joint angle very much.
However, the manufacturers of the pto shafts and provide a warranty for them have a good idea on what angles they can endure and that is why they provide the angle charts in the material that comes with a new pto shaft.
Dave M7040

 

[Gary Fowler]

I think you are forgetting that a slip clutch and a shear pin both have two flanges that attach between the gear box and driveshaft. A shear pin type takes up at least 4" where a slip clutch may take a bit more but not a significant amount. I don't believe it is enough difference to significantly affect the drive shaft angle.
I have use both and had no problems with either. My brother in law has a Fred Cain bush hog and it is the worse thing I have ever seen about shearing bolts especially at initial start up. There is a fine line between shearing a pin and stalling the tractor. His NH has no clutch so there is no such thing as feathering in the PTO, it is either full on or off.

 

[SPYDERLK]

My brother in law has a Fred Cain bush hog and it is the worse thing I have ever seen about shearing bolts especially at initial start up. There is a fine line between shearing a pin and stalling the tractor. His NH has no clutch so there is no such thing as feathering in the PTO, it is either full on or off.

So start w pto engaged.

 

[EddieWalker]

Got home yesterday about noon and put in 6 hours mowing trees to clear about 2 acres. This is an area that was cleared about five years ago, but with other projects, I sort of let it get away from me and haven't touched it in awhile. Trees are the worse kind of weeds!!!! This is probably the fourth or fifth time this year that I've been able to get out there due to the rains. So far, I haven't had a single issue with the mower. This is my first year with the slip clutch and I'm very impressed!!!!!

Eddie

 

[Fallon]

If you pop sheer pins often or do aggressive things I'm sure the extra cost & maintenance is worth it. But if you are like me and doing mostly pasture mowing & have yet to pop a sheer pin, probably not as worth it.

Also the sheer pin is what connects the PTO shaft to the gear box. There is a grove on the shaft & a set screw to let the shaft spin on the gearbox stub without falling off when the sheer pin breaks. Really its not any longer than a without the sheer pin. I'm sure the slip clutch adds an extra several inches. Whether or not that is significant enough to cause impactfull changes to the drive line angle is up for debate too.

 

[LTJ]

I'm looking for a cutter to run off my Kubota L2350 right now. The spec sheet says the PTO has an overrunning clutch. Does work the same as having a slip-clutch as part of the cutter?
Thanks, Terry

 

[Fallon]

An over run clutch let's the tractor drive the PTO shaft. But it prevents the PTO shaft from driving the tractor. Completely different than a slip clutch like we are talking about here.

If you have a big flywheel like a rotary cutter it will drive the transmission even after you push in the clutch making it so your tractor won't stop. Big safety issue on older gear transmission tractors.

 

[ovrszd]

Sorry, I didn't read all the posts.

I have both.

If you are going to use a cutter in extreme conditions, hitting rocks, stumps, trees too big to cut, etc., I think you should have a slip clutch.

If you are going to be very cautious about what you cut you can get by with a shear bolt just fine. I've had my shear bolt cutter (6') for 4 years now and only sheared 2 bolts. I actually think I just wear them in two.

 

[Citydude]

I've broke 3 shear pins in two years of contract mowing. One on a chunk of cement, another on piece of drill pipe and the last one on a short block V8. People leave the darnedest things laying around.

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