Yanmar YT3 series (YT347/YT359) IHMT/I-HMT Transmission workings

[freightboy]

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

I concede that the Fendt is not a CVT in a traditional sense. After watching this, I understand more about it. That said, the I-HMT is not a scaled down version of this vario transmission. While it uses some of the same principles, there are major differences in the operation. The engine is directly connected to the I-HMT with an inner shaft. The outer shaft is connected to the motor and provides the output. The pump and motor are on the same shaft. The forward and reverse clutches are controlled by hydraulic solenoids that allow it to switch from forward to reverse while on the move. When in neutral, the pump still spins, and the motor spins in the opposite direction giving it neutral. This is different than the Fendt.

 

[freightboy]

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.

Didn't see the video at first. See above post. They are very different, but do share in a few areas. Just like the Continuously Variable Transmission, in the title is different, so is the Vario. I don't recall ever seeing the Vario in any literature before for the I-HMT.

 

[ptsg]

Didn't see the video at first. See above post. They are very different, but do share in a few areas. Just like the Continuously Variable Transmission, in the title is different, so is the Vario. I don't recall ever seeing the Vario in any literature before for the I-HMT.

It's literally the title in the European Yanmar page. Even includes "Highly efficient variable transmission i-HMT".

i-HMT Transmission - Yanmar Europe Agri

Yanmar YT347 (47hp) and YT359 (60hp) tractor with i-HMT (Vario) transmission, smooth and step-less gear shifting from zero to maximum speed.

www.yanmar.com

 

[freightboy]

Both transmissions, both variable, both make wheels turn, I can give you that. Now being a scaled down version, take a look, they are not the same. Mechanically they are very different. As pictured above, the shaft you see on the right of the I-HMT is the input shaft. Moving to the left is what actually turns the wheels, some would call it a motor, but the motor is on the right side of the next component, and the left side is the pump. In that pump/motor combination there are pistons that shuttle hydraulic oil from the pump side to the motor side. When in the working range, they are hydraulically locked, thus providing direct power to the ground.

 

[Dick_Timmerman]

Well Freightboy, for the input shaft you're correct, for what makes the wheels turn you're not. Actually, the first big cylindrical part (with the sloped surface) what is situated on the input shaft is what makes the wheels turn. The shaft protruding on the left is actually the input shaft. The magic happens in the second cylindrical part which houses the pump as well as the motor side. Also the directional valves are in this part. due to the position of the swash plate the plungers in the 2nd cylindrical part are pushed in, creating hydraulic pressure. on the opposite side of the block 180° turned, the other plunger is pushed out. this makes the first cylindrical part to rotate slower faster or exactly the same speed as the inputshaft.

 

[Dick_Timmerman]

John Deere loves their 3-cylinder turbos. Kubota engines are all 4-cylinder turbos, if they are so equipped. I don't think there are reliability issues with turbos, but I prefer a 4 cylinder over a 3 cylinder any day of the week. It simply is a smoother engine.

JD up to 105hp are all yanmar engines. Open the bonnet, look closely, somwhere there's a sticker with "Yanmar" on it. Even, the 2014 JD 2032R is except for the bonnet completely Yanmar.

 

[freightboy]

The thing to the left holds the transmission in the housing and does not move. There is an outer shaft that isn't pictured in this that is over the input shaft that turns the wheels.

 

[Dick_Timmerman]

There is an outer shaft that isn't pictured in this that is over the input shaft that turns the wheels.

Sorry, not true, the outer shaft is visible.
Lets show a animated movie.
Input shaft, the shaft with the spline on the right side.
Swash plate, the light blue part which is regulating the pumped volume.
The grey block in the middle with the plungers in it, which is the hydraulic motor and pump combined in one body.
The magenta "reaction block" is set in motion by the pump block.
If you look closely you'll see some small cylinders between main shaft and plungers
Those are the directional valves which open and close the flow into the caverns with the plungers in it.
The grey part which is mounted on the magenta "reaction block" IS the output shaft of the unit and has an internal spline which holds the three cogs for low, mid and high range.

The big trick, when this unit breaks, you can interchange the unit by unscrewing some 8 bolts, pull the unit out on the back of the tractor and put the new one in.

Have also made up a PowerPoint but somehow I'm afraid of getting in trouble when I disclose that here.
Might get in trouble with posting this animation, have done the job for EU-Type approval @ Yanmar Europe.

 

[freightboy]

Sorry, not true, the outer shaft is visible.
Lets show a animated movie.
Input shaft, the shaft with the spline on the right side.
Swash plate, the light blue part which is regulating the pumped volume.
The grey block in the middle with the plungers in it, which is the hydraulic motor and pump combined in one body.
The magenta "reaction block" is set in motion by the pump block.
If you look closely you'll see some small cylinders between main shaft and plungers
Those are the directional valves which open and close the flow into the caverns with the plungers in it.
The grey part which is mounted on the magenta "reaction block" IS the output shaft of the unit and has an internal spline which holds the three cogs for low, mid and high range.

The big trick, when this unit breaks, you can interchange the unit by unscrewing some 8 bolts, pull the unit out on the back of the tractor and put the new one in.

Have also made up a PowerPoint but somehow I'm afraid of getting in trouble when I disclose that here.
Might get in trouble with posting this animation, have done the job for EU-Type approval @ Yanmar Europe.

I have removed the transmission on several occasions, not out of necessity, but for training. I agree, it is not a good idea to share proprietary info. I have the mechanical schematic, but once again, proprietary. The flat rate for removal and re-installation is 4.5 hours. That is less time than splitting other tractors to get to the transmission. Here is a video with a cutaway version of the I-HMT that shows the plungers you are talking about. They allow fluid to go from side to side of the plunger block. The output shaft is connected to the part on the right and connected to an outer shaft around the input shaft. That is where it is connected to the reverser that is controlled by 3 solenoids and then to the ranges.