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Some of you may have seen this on other sites, Yanmar has some new tractors coming out in the spring

YT235 35.5HP Rops Tractor.
YT235 35.5HP Factory Cab Tractor W/Heat & Air Conditioning.
YT347 47HP Rops Tractor
YT347 47HP Factory Cab Tractor W/Heat and Air Conditioning.
YT359 59HP Rops Tractor
YT359 59HP Factory Cab Tractor W/Heat and Air Conditioning.


I don't really want this thread to be about the tractors, but about the YT3 lines transmission which they call I-HMT (Hydro Mechanical?). I've seen it described as "It is not mechanical, it is not hydrostatic : it is the best of both worlds." Some pictures at this foreign language site komunální technika, reportá?e

Can anybody explain this type of transmission? I think I have read that some larger tractors have it.
 

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Yep, I still don't understand it. :gaah::think::smash:
 

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Hmm. Interesting concept.

Here's what I think I got out of the PDF Jim posted.

In a nutshell, the engine spins a shaft to a planetary gear system with its output directly tied to the final drives. This represents the mechanical or normal gear transmission if you will. A hydrostatic pump and motor is the infinitely variable part of this equation. The engine output shaft also drives this hydraulic pump. The output of the operator controlled hydraulic motor drives a part of the planetary which in turn varies the output RPM of the planetary gear set which in turn changes your wheel speed. Pretty cool.
 

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Hmm. Interesting concept.

Here's what I think I got out of the PDF Jim posted.

In a nutshell, the engine spins a shaft to a planetary gear system with its output directly tied to the final drives. This represents the mechanical or normal gear transmission if you will. A hydrostatic pump and motor is the infinitely variable part of this equation. The engine output shaft also drives this hydraulic pump. The output of the operator controlled hydraulic motor drives a part of the planetary which in turn varies the output RPM of the planetary gear set which in turn changes your wheel speed. Pretty cool.
I'm not good at this. Are you saying that as you press down on the forward pedal the RPM's and speed picks up without having to mess with the throttle control?
 

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Yes, hence the variable speed/output. You essentially change gear "ranges" and use the "go pedal" to change the speed within that range. ....If I understand the concept correctly.
 

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Hmm. Interesting concept.

Here's what I think I got out of the PDF Jim posted.

In a nutshell, the engine spins a shaft to a planetary gear system with its output directly tied to the final drives. This represents the mechanical or normal gear transmission if you will. A hydrostatic pump and motor is the infinitely variable part of this equation. The engine output shaft also drives this hydraulic pump. The output of the operator controlled hydraulic motor drives a part of the planetary which in turn varies the output RPM of the planetary gear set which in turn changes your wheel speed. Pretty cool.
And the leg bone is connected to...????? :laugh:

Thanks for the explaination Diesel.
 

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How about a been there,,, done that machine,,, :dunno:



This machine moves by a band stopping the outside of the planetary,,,
it has several planetary's to "stop" for various speeds,,,



I believe the Ford Model "T" worked like this,,, but I have never operated one,,

I did own two of the UFT tractors, though,,, :thumbup1gif:
 

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That's not the same. Stopping the planets or ring isn't like varying the speed at which it is rotated. Infinite speed output vs fixed. That's relatively new.
 

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I bought my wife a new 2015 Nissan Versa Note last April, and they are using this same CVT transmission in some of their newer vehicles.
We have about 8,000 miles on it now, no problems at all with it, so far. :thumbup1gif:
 

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A CVT transmission that many auto makers are using are basically snow machine or four wheeler style variable sheave diameter belt transmissions, only more heavy duty. Completely different design and operational theory than a hydro-mechanical transmission.
 

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A CVT transmission that many auto makers are using are basically snow machine or four wheeler style variable sheave diameter belt transmissions, only more heavy duty. Completely different design and operational theory than a hydro-mechanical transmission.
Both of my daughters learned how to drive a CVT before learning manual transmissions,,

This is the CVT they learned on,,,



They still come home to drive the CVT!! :thumbup1gif: but, they both drive a manual transmission on the road,,,
 

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it a very interesting concept. but my big question is, why? we have good transmissions, and they aint broke, so why fix them?:think:
 

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Discussion Starter #17 (Edited)
it a very interesting concept. but my big question is, why? we have good transmissions, and they aint broke, so why fix them?:think:

One of the reasons I started this thread is what is the advantage of this transmission. I've read that this first time this type of transmission has been used in a tractor under 50HP.

The I-HMT, however, offers a much higher grade of efficiency than the hydrostatic transmission almost comparable to that of a mechanical transmission. Owing to these unique characteristics the tractors equipped with this type of transmission have up to 15% higher pulling force which leads to lower diesel consumption. It is also possible to use such tractors for heavier work without the risk of lowering the lifetime of the transmission.
Two other links I'm still reviewing.

https://www.youtube.com/watch?v=3V7dVk0j-q8

A PDF paper from Iowa State (or maybe just about an Iowa State Design, I'm still reading it)
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=0ahUKEwigopzr8dvKAhVHv4MKHbKHAJ0QFghEMAY&url=http://powersolutions.danfoss.com/workarea/downloadasset.aspx?id=17179880492&usg=AFQjCNHoGXYCWsKSsVLCNbWQSOggsS14jQ&sig2=Ow__w0MZVdOs1k23Hz_00A


Edit: The youtube video is pretty good, and pretty much shows you what Jason describes above in the animation.
 

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So what this does for a scut or cut tractor if they make it for them, is I get a computer telling me I'm doing to much work by having to use my right hand to operate the throttle. And seeing as I am already using my right foot on the foot feed I can do it all by just using my right foot. And I get to have another computer on my tractor that could shut me down when it wants to quit working. I can see this on AG tractors as being a good thing for all that they have to do in them. How's that for driving the price up?! :munch:
 

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There doesn't necessarily need to be another computer. The controls would be similar if not identical to what you have now. The major difference would be more pulling power and less heat since the transmission is more efficient. Higher efficiency means less HP is turned into heat and is available for you to use. That's a big plus. :good2:
 

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Proven design

A CVT transmission that many auto makers are using are basically snow machine or four wheeler style variable sheave diameter belt transmissions, only more heavy duty. Completely different design and operational theory than a hydro-mechanical transmission.
The variable speed belt drive was also used on combines and possibly other ag machines. I'm not sure they would work as well on the very high horsepower ag machines now but they worked well on older machines. Even on those, the belts were substantial. I'm guessing there would be internal heat build up in a belt strong enough to handle high horspower/high torque engines of today.

Treefarmer
 
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