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SLIP CLUTCH VS the OVER RUNNING COUPLER ( ORC )


They are 2 completely different devices. An ORC allows theimplement, like a mower, to freewheel if the tractor pto slows down lower than the implement rpm. this is usefull in older single stage clutch, non live pto tractors like the ford 8n, NAA, etc.. because if you step on the clutch, the pto inertia will still be transmitted back to the transmission and drive the tractor. Live and independent pto machines do not need the over-running capabilities of an ORC from a safety standpoint.. There is however one use for an ORC on an independent pto machine.. many of them have a pto brake to slow the pto down when you disengage it. if you have a large mower on a machine.. like a 10' mower.. when you disengage the pto, the brake gets quite a bit of wear . with an orc. the pto will stop immediatly, and the mower will coast to a stop. In general, to minimize pto break wear, you should idle the engine down very low before disengaging the pto.. and similarly.. to prevent driveline shock, the pto should only be engaged at enough rpm so that the load won't stall the tractor.

Now.. for a SLIP CLUTCH.. that's a torque limiter and goes inline with the driveline.. if the mower hits an object that stops or slows it.. instead of shearing a shear pin.. or perhaps damaging the driveline or the tractor, the clutch will slip at a pre-set torque value. torque value is usually adjusted by spring tension on bolts onthe clutch. also.. slip clutches should be 'exercised yearly by loosening them til they slip a little, then retorquing them.. this prevents them from rusting up and not slipping when needed.

buy a slip clutch that will match the needs of the implement. for instance.. if you have a 60hp tractor, and are using a mower that has a 40 hp gear box.. get a slip clutch that you can set to slip at 40.. etc..

soundguy
 

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Good information, I am sure there are many who do not understand the difference between the two.
 

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Excellent explanation of each type, and thanks.

Now, a question: Can both be used simultaneously? On my old Ford, the ORC is essential to get stopped when I want to rather than when the shredder winds down. At the same time, I can see where the slip clutch would be essential to keep from putting "shock" loads on the PTO shaft.

Thanks ..
 

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Yes you can and SHOULD! The OCR protects the drive by allowing the operator to stop the tractor and the slip clutch protects the PTO driveline and tractor. If you have a live PTO then the slip clutch is all you need.
 

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Yes you can and SHOULD! The OCR protects the drive by allowing the operator to stop the tractor and the slip clutch protects the PTO driveline and tractor. If you have a live PTO then the slip clutch is all you need.
Figgered as much but it's nice to get confirmation. Thanks JohnW.
 

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I forgot to put the ORC on the old Ford the first time I hooked up the mower in the Spring a few years ago and ran the tractor right through a fence! Dumb on my part, but I haven't forgot it since! Grin.
 

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As of right now, I am no longer in that group of people!

Good concise and simple explanation.
I too am coming out of that group, but I was more looking for answers on using both when I found this thread. I am running a 4' Bush Hog brand behind my '48 8N, but have neither of the clutches. I believe I need both. Where's the best place to purchase these on a budget. I'm not cheap, just currently broke.
 

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Got an ORC for my 1950 Ferggie, after reading several wise men's posts on MTF.

I sheared a shear bolt on my new 48" bushhogg when I hit a log hidden by tall grass while using my TYM-T233. I'm sure the hit wasn't good for tractor or mower gearbox even with the protection of the shear bolt!! Think I'll be purchasing a slipclutch for my bushhogg on my next trip home!

Here's a slip clutch at TSC (Read the review for shaft sizes, I'll have to check mine before I buy!!):

http://www.tractorsupply.com/en/store/pto-slip-clutch-1-3-8-in-smooth-shaft




THANKS!!
 
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