Hiya Farmboy, nice to see you again.
Hey, there's something I'd like you to take a VERY hard look at. I LOVE my HST, and for what I do, in fact I can hardly even imagine not having it. In the process of getting logs (some of them VERY heavy), brush, trees and limbs out of customers' back yards, I am constantly winding my way through tough spots, around obstacles, dodging mailboxes, fences and lamposts, on a WIDE variety of terrain, some of it very treacherous.
HOWEVER - for what YOU are doing, I would REALLY like you to think about the GST transmission. (For those who are not familiar with Farmboy's intended uses, here is the link to his first thread,
M4800 - MX5000 - L5030 . In it, he tells about the <font color="red"> 60-80 acres of bush-hogging </font> and<font color="red"> 40-50 acres of tilling</font> he needs to do.)
That is a LOT of ground-engaging work, and the HST is going to get VERY HOT, please believe me. Over 200 degrees at times, close to 210 in fact. To ensure HST longevity, it would IMHO be almost mandatory that you equip the tractor with an auxiliary oil cooler if you're going to do all that ground-engaing. Plus, you will of course lose 1.5 PTO hp by going with the hydro over the HST. Not that big a deal one might say? But consider this. A human being working at maximum effort produces about .1 HP. So when you lose 1.5 PTO hp, that power loss is converted almost entirely (entirely?) into heat, in this case, the heat equivalent of 15 hot sweaty guys, constantly being dumped into your hydraulic fluid. Just their heat mind you - you don't even get to take advantage of the work that they could be doing.
As for hydro heat and longevity: some might say, hey, I've used my hydro very hard for XXX hours and I've had no problems, etc. That reminds me of an exchange I had with my brother a few years ago. I was talking with him about vitamin supplements, and asking him to reconsider his position on them (that they were totally unnecessary, he has never taken them, and is in PERFECT HEALTH). Several months later, a grapefruit-sized malignant melanoma was found in his chest. I have very little regard for anecdotal evidence, and so of course am claiming absolutely no connection between his abstention from vitamins and his cancer. (He's fine now by the way). The point of my story is that you might THINK that your hydro is doing just fine in the face of high temperatures, but out of sight, and out of mind, trouble might be brewing.
I have a very high regard for science, and physics in particular. You CANNOT fool physics, and there is no way that the kinds of sustained high temperatures that you would encounter with all that ground engaging will not shorten the life of your hydro, the only question IMHO is by how much. There are some very good threads on this, and as I said, an auxiliary oil cooler would be practically a MUST. With one, you might be able to get your hydro temps down to about 180 F. But again, you'd still be losing PTO HP.
Lastly, the GST is NICE. I would like to suggest that you PM two people before you buy, and ask them to look at these two threads, and hopefully "weigh in" here. One is "Skypup" (Thom) and the other is "5030" (Daryl). Between the two of them, they could give you some VERY useful input about which tranny would be best for you.
I do NOT believe that tranny is the HST, as much as I love it. You are tilling a LOT of acres.
All, please chime in. Would you use a hydro to till 60-80 acres?
Good luck FB,
John