When you are backing a tractor with a 1200+ lb flail mower up a slope too steep to drive up, and you're doing it a hundred+ times in a row on a hot summer day with the A/C on in the cab, and the HST is performing well and getting the job done...yeah, you don't need to overly complex Yanmar transmission. Pushing the weight of the tractor and implement up that long steep slope a hundred plus times is easily the equivalent of working a ground-engaging attachment.
Yanmar YT3 series (YT347/YT359) IHMT/I-HMT Transmission workings
- Thread starter eekbin
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When you are backing a tractor with a 1200+ lb flail mower up a slope too steep to drive up, and you're doing it a hundred+ times in a row on a hot summer day with the A/C on in the cab, and the HST is performing well and getting the job done...yeah, you don't need to overly complex Yanmar transmission. Pushing the weight of the tractor and implement up that long steep slope a hundred plus times is easily the equivalent of working a ground-engaging attachment.
freightboy
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The I-HMT will outperform a hydrostatic in the same category without exception. As far as overly complex, it isn't. It is actually quite simple. It can be removed and re-installed in around 4 hours if the need ever arises. That time counts taking everything off and draining fluids. If you are speaking of operation, one pedal and one lever are the major differences. It isn't complex, just different.
ptsg
Super Member
The I-HMT is just a scaled down version of the Vario Transmission used on Fendts. Yes, it does have an HST in there but that actually does very little work. There is still the mechanical transfer of power that handles most of the work load.
I suggest watching some videos on how the Vario transmission works. Can't even be compared to the HST.
normanb seems to have real world experience with both transmissions.
I suggest watching some videos on how the Vario transmission works. Can't even be compared to the HST.
normanb seems to have real world experience with both transmissions.
freightboy
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I am not familiar with the Vario transmission, but do have a lot of experience with the I-HMT. I started as a skeptic, but it won me over, it is much more capable than either a shuttle shift or hydrostatic transmission. I will look up the Vario trans to learn more about that.
freightboy
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Looked it up. The Vario is a CVT, not similar to the I-HMT.
ptsg
Super Member
Vario is not a CVT. Even Yanmar calls theirs Vario because it's just a scaled down version of the Fendt Vario one.
Fendt Vario:
HMT:
HMT, new type Transmission - Technology
This is the introduction of HMT, new type Transmission.In the field of gears, hydraulic equipments, transmissions, marine gears and mashine tools ,Kanzaki Kokyukoki Mfg. Co., Ltd. tries to solve the problems of our customers globally.
www.kanzaki.co.jp
freightboy
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I-HMT stands for Integrated Hydro-Mechanical Transmission. It is not a scaled down version of this transmission. It has the hydraulic pump and motor on the output shaft from the engine. The pump always rotates. With the swash plate in what would be the neutral position in a hydrostatic transmission, the I-HMT would be neutral. The input shaft on the pump rotates, and the motor does a counter rotation on the same shaft to keep the outer shaft at neutral. When the swash plate is in what would be the neutral position on a hydrostatic transmission, the I-HMT hydraulically locks the shaft and provides direct power, much like what a gear driven tractor would do. When the swash plate is in what would be the forward position on a traditional HST, the motor side of the I-HMT increases the speed, up to double speed. This gives maximum efficiency when travelling.
ptsg
Super Member
Just like the Vario....
There is a reason why Yanmar also includes the word "Vario":
freightboy
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ptsg
Super Member
Wow. Did you even bother to look to the video and link I shared? It's literally the same thing.
You seem to believe that Yanmar came up with this crazy innovative idea. Guess what? They didn't. Fendt did it and has been using these transmissions for years. Kanzaki then, managed to create a scaled down version of the Fendt Vario and called it HMT.
I really can't understand what other differences you see in both transmissions other than different naming, if you bothered to actually learn how the Vario works that is.