ArlyA
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My thoughts exactly. What you need to do with your machine dictates the best drive.
4570Man
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I just saw this on ticktok. Looks like a HST pulling trailers to me.
LouNY
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Somebody believes in abusing equipment.
oldnslo
Super Member
Is that a feed trough in the foreground of that video clip with skid pulling hay racks? Makes me wonder if just moving short distance on known flat ground. Either way could be interesting turning if pulling very hard.
On the subject of HST vs gear...
In my search for a new tractor, I came across the Yanmar YT series. I have to say that I am impressed with the i-HMT trans they are running in those tractors. It appears to be the closest I've seen to "the best of both worlds" between HST and gear.
1. I like the small "power-reverser" lever to change between F/R, allowing for just one "go" pedal. That is obviously a matter of personal preference, but I think I would find this solution a little more convenient.
2. This TBN post (point #6) states that the IHMT transmission in the Yanmars has the ability to "lock up" on steady pulls. I've wondered if that is possible with HST and assumed not, but if the Yanmar trans somehow does this, that is great.
IMO, the above two items bring some of the best features of an expensive power-shuttle transmission to HST.
In my search for a new tractor, I came across the Yanmar YT series. I have to say that I am impressed with the i-HMT trans they are running in those tractors. It appears to be the closest I've seen to "the best of both worlds" between HST and gear.
1. I like the small "power-reverser" lever to change between F/R, allowing for just one "go" pedal. That is obviously a matter of personal preference, but I think I would find this solution a little more convenient.
2. This TBN post (point #6) states that the IHMT transmission in the Yanmars has the ability to "lock up" on steady pulls. I've wondered if that is possible with HST and assumed not, but if the Yanmar trans somehow does this, that is great.
IMO, the above two items bring some of the best features of an expensive power-shuttle transmission to HST.
ericm979
Super Member
My understanding is that the iHMT doesn't have a full lockup like modern torque converter automatic transmissions in cars do. HSTs are most efficient when pumping small amounts of oil, which is normally when barely moving. IHMT makes it so that most efficient range matches speed of normal use.
ning
Elite Member
Yeah I can't imagine how a hydraulic drive could "lock up". With torque converter automatics, there's basically a magic hydraulic fluid clutch - a fluid coupling - between the two mechanical drives and the lockup just takes the fluid out of the equation by using an automatic clutch. The tractor hydraulic drive is very different because you have a hydraulic pump over here.................. and then way over there you have the other half, the hydraulic motor driven by the pump. You can't just stick a clutch between them without putting a driveshaft between the pump and motor, and if you did, it wouldn't be a hydraulic drive any more but a torque converter system.
LouNY
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If the drive is a hydraulic pump that feeds a hydraulic motor if doesn't matter if they are close coupled or separated. One combined unit or two separate units it is still a hydrostatic drive. Torque converter drives are completely different critters in them the torque converter replaces a clutch.
ptsg
Super Member
Check some videos about how the Fendt Vario transmission works. The i-HMT is a scaled down version of it.
Yes, the hydrostatic pump and motor will lockup by angling the swash plates in a way those are technically working against each other. This causes the the power to be transferred through a planetary gear and the tractor is then mechanically driven at higher speeds where the typical HST would fall on its face.
Yes, the hydrostatic pump and motor will lockup by angling the swash plates in a way those are technically working against each other. This causes the the power to be transferred through a planetary gear and the tractor is then mechanically driven at higher speeds where the typical HST would fall on its face.
LouNY
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yep, I put just the smallest amount of pressure on the shifter when almost stopped but not under a pulling load or when the engine is providing hold back.
bdhsfz6
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The manuals for my Kubota HST tractors say to throttle back, take your foot off the treddle and come to a near stop before changing gear ranges. I find it's sometimes easier if the tractor is moving slightly.
Gear changes are a lot less frequent with the HST plus transmission, since you can shift on the fly.
Gear changes are a lot less frequent with the HST plus transmission, since you can shift on the fly.
Sawyer Rob
Super Member
Gear changes are a lot less frequent with the HST plus transmission, since you can shift on the fly.
I can shift on the fly with my gear drive too, up or down as the gears are synchronized.
SR
I can shift on the fly with my gear drive too, up or down as the gears are synchronized.
SR
I don't understand. Is it really "shift on the fly" if you have to "come to a near stop"?
RjCorazza
Elite Member
He is referring to the Hi-Lo in each of 3 ranges, which is shift on the fly. My Kubota HST+ transmission requires a complete stop to shift between the H/M/L ranges.
It's a great transmission, and can also auto shift the Hi-Lo based on load.
ptsg
Super Member
You have to stop to change ranges. Helps if you let it roll very very slowly. Applies to either type of transmission, gear or HST.
Now that you mention it, I do remember seeing something, somewhere, about a hi/lo within ranges. Sounds pretty nice.
Most of my reading/looking has been on Branson/TYM tractors. Guessing those do not offer this or I would have read more about it...?
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I had another question about HST vs gear, and it hit me to ask Google's AI, since it knows everything:
(text above was highlighted by Google, with more info on each of the four items offered below the above text)
After I read the above, I was thinking that HST is best for lower power applications, but I remembered that I've rented articulated wheel loaders before. They were larger than a utility tractor, and they are HST?!?
I guess that the word "loader" in articulated wheel loader is key. A wheel loader is more focused on a single task than a utility tractor, and that task is 99% back and forth, stop, start, reverse, etc, and that is the area where HST excels.
(text above was highlighted by Google, with more info on each of the four items offered below the above text)
After I read the above, I was thinking that HST is best for lower power applications, but I remembered that I've rented articulated wheel loaders before. They were larger than a utility tractor, and they are HST?!?
I guess that the word "loader" in articulated wheel loader is key. A wheel loader is more focused on a single task than a utility tractor, and that task is 99% back and forth, stop, start, reverse, etc, and that is the area where HST excels.
ning
Elite Member
yeah, I think a lot of CUT work is perfect for HST and HST is perfect for it, while utility tractors tend to be more in the.... tractor.... application, where HST can be a negative and there's little point of having it.
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