greg_g,
Hey, is there any chance you could post that Eurocardan chart? That's the shaft that came with my tiller, and probably the majority of the others also, but the KK manual doesn't list anything like that. I still think the method that I posted is what KK wants you to use, but the chart would be interesting. I definitely wouldn't set the slip clutch according to a chart though, at least not without some guidance from the tiller manufacturer, whoever it is, this isn't necessarily limited to KK. I'll explain why in a bit.
FWJ... You're right that there's several different brands that KK used over the years, but I don't think that's what KK wants you to do... at least according to their "procedure" (and I use that term pretty loosely
). You're right, when we KNOW how much HP or torque we need to transfer... but in the case of our tillers, we really don't know this number. We've got an idea, but, no hard numbers.
For example, let's say that Seapea, or any of us for that matter, had greg_g's chart, and we decided to set the slip clutch to transfer up to 35hp (just for the sake of discussion) because we have a 40hp tractor (again, just for sake of discussion). Also, since we know that the tiller has gearboxes rated for at least 50 hp (because we know that they use the same gearboxes on all of the models, and the 72" is rated for up to 50hp) so we assume that setting the clutch for 35HP gives us at least a 5HP cushion, so everything will be OK.
Now we're tilling along with our 48" tiller on our 40 HP tractor, with the slip clutch set to transfer 35HP. Everything's going great until we hear a big bang underneath the tiller, and the tines stop rotating and the clutch slips. We think everything's OK, because we have set our slip clutch correctly according to the chart, right? But, we go back to see what we hit back there, and find that buried truck axle again. We also see that 1 tine is twisted back like a pretzel. HOW COULD THAT HAPPEN? Here's how:
In reality, it was only taking about 14 hp (an arbitrary, but realistic number) to drive the tiller in our hardest soil conditions. If we have that slip clutch set to transfer 35hp, then that one tine that caught the truck axle had to transfer 21 extra horsepower to that truck axle all by itself before the clutch would slip. So, in essence, that one tine had to transfer nearly double the amount of power that it was actually taking to drive the tiller, and it was just too much for it to withstand, and it yielded. Time to buy a new tine. Did the slip clutch do it's job? Well, it slipped at the torque level it was "set" for, but it was just set too tight, and we damaged the tiller. So, in effect, no. Not through fault of the clutch, but operator error.
That's why I think that the way the KK manual "leads" you to do it (and the way that I posted) is correct. You only want to transfer the amount of torque necessary to get through your toughest obstacle-free areas, and not much more than that at all. That way when you hit that truck axle or whatever else lurks in the depths of our gardens, food plots, etc.
, there's much less risk of damaging anything. The only real problem I have with it, is that we don't know how much more torque we're setting the clutch for by making, let's say, 1/2 turns on the nuts, since that's what I advised. But, that's what I did on mine.
If we arbitrarily set the clutch off of a chart, without any guidance, then we're getting into "shear bolt" territory, without the shear bolt. Which is fine, if the manufacturer gives some guidance about where to set the clutch for the particular tiller model... but unfortunately, they don't. They leave it up to us to figure it out on our own. You could certainly set the clutch for a lower HP number, but that's just a guess too, and if it slips without hitting anything, in reality, what are you going to do? I believe that the way I posted earlier is the proper way to do it, as long as you make small adjustments, and make sure that the slip clutch has completely cooled after it has slipped. And, it works for pretty much any brand of slip clutch that KK may have used.