"I am wondering how the bearings (and the inner splines) of the tractor PTO will handle the rotating weight of the bigger u-joint and shaft, that will get pretty heavy for it I guess. Added to this, the 1-3/8" 6T are meant for 540rpm, the forces will increase a lot at 2000rpm, adding load to the tractor parts."
Now that you say it and I've thought about it, the rotating mass of an adapter (homemade or otherwise) with the 540 knuckles and shafting probably would put an excessive amount of stress on the system. Not only would that be hard on bearings, but it would probably start smoking belts, too.
I've seen those shafts in Surplus Center's catalog and have been thinking long and hard about doing something with those. For those of you on Facebook, there is a page for Massey Ferguson lawn mowers there and a guy posted a picture of a (supposedly) super rare 2000rpm to 540rpm PTO adapter gear box that was evidently made specifically for MF 1450/1650/1850's. It's probably exactly what you are talking about, MacWorld. It was pretty neat but it stuck out so far that it rendered the 3 point arms useless without adding any kind of extension... which seems like a bad idea to me. However, I've been poking around the ole internet some more and think I may have found what I need:
If I've made all my measurements with my good eye, that puppy ought to fit right in there without any kind of modifications needed. It seems a bit pricey to me, but there is surprisingly not many other solutions to be found without extensive manufacturing involved. The way I figure, I could buy this one yoke weldment and assemble the PTO shaft with less expensive parts the rest of the way to my mower gear box.
Edited by KennyP, April 13, 2018 - 04:52 AM.