Slip clutch attachment to replace shear pin

Gary_in_Indiana · Jun 3, 2003

The weakest link theory makes a lot of sense to me in the case of a clutch failure. If I don't get bolts with whichever clutch I get, it sounds like going with the grade five makes more sense in terms of safety.

Would anyone care to address the "slip clutch vs. over riding clutch" question? Ild love to hear the pro's and con's of each before I make a mistake and buy the wrong one. Thanks!

gerard · Jun 3, 2003

Two totally different animals and you MAY want both if that can be done. The Overrunning clutch prevent your tractor from being pushed forward from the momentum of the spinning blades. Most newer tractors have it built in, pretty easy to tell. If you feel the tractor still wanting to go forward after you throw the clutch in on a level surface and you have to stand on the brakes, you don't have one. The slip clutch just prevents driveline/pto damage when the blades hit an object to big to cut. Instead of the bolt shearing, the clutch "slips", preventing driveline damage. Personally I'd like one for my posthole digger, which shears bolts regularly but I've only sheared one bolt on my bushog in three years of cutting so a slip clutch on that would not be beneficial.

Gary_in_Indiana · Jun 3, 2003

<font color="blue"> Overrunning clutch... Most newer tractors have it built in </font>

My John Deere 4200 is at least a 2000 and I think a 2001 so I probably have that feature already. Sounds a like slip clutch might be the one to purchase (the more expensive one, of course). Am I on the right track here?

MarkV · Jun 3, 2003

Gary, I believe you are on the right track with a slip clutch if the goal is to eliminate the need to change shear bolts. If the goal is to keep the tractor from being pushed the slip clutch will not do that for you.

As Slowrev mentioned, be sure and learn how to check the clutch at the beginning of the season. They have a tendency to lock up with non-use and leave you unprotected (as in no slip and no shear bolt) until freed up and reset.

MarkV

centex · Jun 4, 2003

I use a slip clutch on my bush hog but I attach the PTO shaft to it with the same grade 2 bolt as before. I also do what you suggested with my PHD. I have a slip clutch on the PTO but I still use a grade 2 shear bolt on the PHD end. The clutches are set to slip before the shear bolt goes but if for some reason it does not slip I am still protected by the shear bolt. I have only had to replace a couple of shear bolts since I did this. Before I had to carry bags of bolts around and spent a lot of time replacing them. I think I paid around $99 for each of my slip clutches bit I would gladly pay twice that given the results I have had with them.

My PHD used a special shear pin that was 3/8" on one end and 5/16" on the other. My dealer gave me about 50 of them free but I went through them in a couple of weeks. He said that everyone just drilled 3/8" all the way through and used a grade 5 bolt instead even though the mfgr. clearly says to use only grade 2. Of course the user would be responsible for any repairs as drilling the attachment out and using the hardened bolt would void the warranty. The dealer told me that he had never had any warranty problems with these machines but I could not bring myself to do it if for no other reason than I am already using the unit for heavier work than it was designed for.

normde2001 · Jun 4, 2003

I don't know if your JD is still under warranty, or if the PHD and JD dealers are one and the same, but I can't imagine JD rebuilding your PTO under warranty after it self-destructs, (if that's a word), because of using a grade 5 shearbolt.