CVT trannys good pullers?

[Laapa]

I guess I shouldn't read too much into this but I still found it interesting.

I went to a Stock-tractor tractorpull yesterday (haven't seen one of those in a couple of years) and the max. 8500 kg class pull-off was dominated by CVT-trannys.
Two Fendt Vario 716 and a Steyr CVT 170 (in fact, it was the blue painted Steyr I mentioned in a post earlier).

It seems, in this particular case, that the ability to get just the right wheel/engine speed made the difference.
Could this be applicable in real-life situations such as plowing etc?

In the heavy class though a Fendt 926 Vario had less luck against a JD 8310, Magnum and a couple of NH Genisis.

[eppie]

Laapa,

In the Dutch/German test of a few CVT tractors, the ZF/John Deere had a bad score for tractive efficiency. The JD engineers said it was because of tranny pump damage, the pump wasn't lubricated during the PTO test. I think those CVT are good for transport and PTO work like mowing with those 9 meter triple mowers.

Besides, a CVT has 3-4% less efficiency than a powershift model. Just a mechanical transmission with a torquey engine will do best for low speed (about 7kmh) work like plowing, i think.

[Woodbeef]

From what I understand about shiftless-boxes,I have to agree with the "Zetor-Man"!! For actual ground engaging work they are a comprimise. For cropping,spraying,seeding,and transport they seem to be more in their designed element.

[eppie]

I have to say that the production models have been modified since that test with the JD Autopowr. (what about the ZF boxes in the Deutz??

btw: are there more ZF cvt boxes in other tractors?

Renze

[HPP]

As far as puller goes: I´ve never had a ride on a puller but if that day ever comes I sure would like it to be a "CVT" (I prefer to call them "Varios").
First of all you can give it full throttle wich means the engine can develop full power the whole ride, from the very start. Remember: a 926 or in fact most of the 700:s can accelerate from 0 to 50 km/h in 10 seconds! That´s because you accelerate with the maximum power all the way.
When pulling it would only be a matter of ballasting the tractor correctly. I guess on a 926 I would want some 2000 kg up front!
As far as efficiency goes: OK it may be a compromise, but so is the power shift. The efficiency of a Vario is on about the same level as that in a PS. OK it differs between different "Varios" In the test that was mentioned above it was obvious that the original Vario reached the best result. The JD (with a ZF-trannie) was slightly higher in efficiency at around 8-9 km/h but gave less power to the drivewheels below and above that speed.
I can´t help thinking of questions that were asked among farmers some twenty years ago: Should we go 4WD or not? Today they ask should we go Vario or not? I´m quite sure that in say ten years you´re a lot better off coming to your dealer wanting to trade in your old tractor for a new one when the one you bring is a Vario!

[FarmerJohn]

But it is still true that a 4wd is more expensive than a 2wd tractor. The difference is almost about 5.000 euro. As a farmer i would like to go for the tractor that suits me best. Do i really need a 4wd tractor, when the only thing i do with it is tedding or raking grass? No, well then why should i spend a lot of money on something i don't need.

And i think the same thing applies to the CVT's.

[eppie]

I think not.

after 10 years, the Vario will need new pumps and motors, about 20k Euro....

I think electric drive has the future, just like in the railway locomotives with Diesel/electric drive.
The electric drive will also meet some skepticism at farmers, and it will need to loose some weight, but thats just a matter of time.

Rudolf rules...

[HPP]

I remember once at a fair, some 18 to 20 years ago. I was lectured by a farmer who thought that all manufacturers and dealers where crooks pushing on to the poor customers machinery they didn´t need. He was talking about 4WD.
I asked him who made the desicion when he bought a new tractor and he said of course he did himself and no damned dealer! My only comment was "and you are the only one on earth!"
I was at a meeting in Marktoberdorf at the Fendt-factory around 1985-86 when the dutch and danish importers told the Fendt-people that their customers demanded stepless gearboxes!
Those guys who make and sell tractors can´t sell what the customers don´t need or don´t want, believe me!
Renze: about new pumps and stuff: That depends on what kind of Vario you buy! Sorry, bad joke! But still I know of some combines (NH) from -79 where the hydrostatic drive never has been overhauled. And, remember also that one of those manufacturers that build Vario-tractors started developing that transmission around twenty years ago. They showed it to the market in -95. That´s when the other guys started to develop their versions!

[eppie]

HPP,

Yes, my previous post on this topic contains a little humor, if you want so.

Please rememer that Vario transmissions in tractors do a little different work than that combine you were talking about, and the combine makes a quarter of the hours of a tractor.  Besides, the pumps of the Fendt vario are "overtuned" standard pumps, the pumps in the Vario (adjustable stroke plunger pump) make a bigger swing angle than standard.

When ZF took over Steyr antriebstechnik, they ate most of the know-how of Steyr, who was on the CVT project since middle eighties. The ZF is the same as the Steyr, but ZF replaced the tooth clutches with wet powershift clutches.

Since Fendt has ties with ZF, i doubt if Fendt was really the first with it. Of course, the one who pays most will run with the honor.

The first Steyr CVT's had major trouble with the tooth clutches, they werent correctly controlled by the computer.

IF YOU WANT TO KNOW THE VERY FIRST CVT TRANSMISSION BUILDER:

Does anyone remember the Heider tractor, built by John Heider, and sold by the Rock island company?? the company was eaten by J.I. Case in 1937

The model C15/27 had a "sliding gear transmission" The system consisted of a small wheel, and a big disc perpendicular to the small wheel. speed was variated by moving the small wheel more or  less to the center of the big disc. In 1950, they went back to the traditional transmission.

I also know of a German prototype of a variomatic transmission, it was in a tractor magazine in 1989 or so.
It had red paint.... NO FENDT...  Does anyone know more about this prototype?? And of the prototype from England, some agricultural university what built an electric CVT based on an old David Brown??

[kenjar]

CVT, Vario........Aren't these tranny's just a different version of the old IH hydro? On the IH there was a swash plate that changed the direction of the oil flow, which in turn changed the direction of the tractor.This plate also increased or decreased the travel speed.

The IH models worked well at pto jobs. They were not as efficient as a geardrive for tillage. Repairs were more expensive and they used more fuel.

Renze,on the Heider tractor, is it the friction drive transmission you are speaking about? The book I looked at says the model 15-27 was replaced by the18-35  in 1927.

[HPP]

Yes Renze, I know that they do a little different job than in the combines. But what the hydrostatic part in the Vario does, to simplyfy it a lot, is actually only braking the outer ring of the planetary gear.
And who was first or not? Well who knows. I know that there has been a lot of different stepless constructions through the years. What I meant saying Fendt were the first was when we´re talking about the Vario-concept. And it might be I´m wrong there too. What I know is that there was a man called Hans Marshall working in the R&D at Fendt. He had the mecanical part of the concept ready in the early eighties. Since then they were developing the software in order to be able to handle it practically.
What I also do know is that Fendt were the first to have it ready to go, out there in the fields, doing hard work.
Unfortunately Mr Marshall passed away shortly before his baby was introduced to the market.

[F6L913]

Hey, what about the Deutz 16006 ?
This tractor have a torque converter with a four speed transmision. There's no clutch on the tractor. The tractor have the same power at 1000 engine rpm than at 2000 rpm. You choose the speed by the acelerator pedal. I think it's the only articulated tractor built by Deutz. Very few of this tractor were made, i think. My father drove one of this for several years. He made about 15000 hours without problems on the Torque converter & tranny, but it had a lot of problems in the axles bearings. Every 1000-1500 hours broke a bearing.
I'll send some pics to AGMachinery. I wish we'll see it soon in the protopipe section.

[eppie]

HPP:

If you give me 10 grand, i will make you a system that handles the Vario mechanically. They can control fuel pumps mechanically, so why not a vario, using the same system based on centrifugal rpm measurement. This system would not swing the fuel plungers, but the stroke of the pump and motor, using a 'power steered' valve.

The Variomatic transmission (with belts) of the DAF car from middle 50's had a belt variator operated by centrifugal regulator and by the vacuum in the intake manifold.

That about the software is absolutely not true. they wanted to take advantage of their new transmission, when the market is ready for it, and when they earned the development costs back from the older transmissions. PLC control exists since the 70's , and developing the program did'nt take 20 years.

The vario only braking the outer ring: Yes, thats correct, but you are making the wrong conclusion out of it:
If the hydrosystem is braking, the function of pump and motor are inversed. The hydraulic system pressure wont be less than when the outer ring is driven instead of braked. Hydraulic power is the same.

Kenjar:

Yes, it is the same as the IH hydro, only the CVT hydro runs via a planetary drive, similar to your tractor's differential.

F6L913:

That Deutz has the same principle as many Diesel railway locomotives, and the Fendt 600 series with Turbomatic E

That Turbomatic E was a torque converter which was blocked by an electronic operated clutch system (the E) when the speed of the outgoing shaft was more than 1700 rpm.

Deutz 16006 : I think you mean that the converter has the same power on the outgoing shaft at 1000 rpm as at 2000 rpm. Not the engine but the outgoing shaft ran on 1000 rpm, when engine ran 2000 rpm. (thats the deal with the torque converter)

[[e-mail]]

I'm F6L913 but i have problems to Log In.

Well Renze, It's very difficult to explain in english.  Before I would say that the tractor had the same traction power independent of the engine speed. With a traditional tranny you can stop the engine at low rpm if you work hard but not with that tractor. The Deutz Agrotron 230 and 260 also have torque converter like the Fendt but is not the same system as in the old 16006.

[eppie]

F6L913

Do you mean the oil flow in the torque converter was adjustable, i mean adjustable fan angle on the driven (outgoing) wheel , the transfer ratio was adjustable??


Ford had that on an automatic car transmission in the fifties.