F1technical.net

What are Continuously Variable Transmissions, how do they work and why where they banned?

Continuously Variable Transmissions are pretty simple compared to regular trannies. However, they cannot take alot of torque due to their design. There aren't much gears in them(or at all), instead a chain connects the input shaft and the output shaft. On both shafts are a set of continuously adjustable cones that point toward each other ( like so >< ). The chain is fitted in between the spaces between the cones. So when the cones are close together the chain moves outwards to the larger radius. This is like a big gear. When the cones move apart the chain slides inwards where the radius is smaller. This is like a small gear. So by constantly adjusting both sets of cones, the engine can always stay in the optimal RPM range as the car's speed changes. This is the beauty of the CVT. However, there are no teeth on the cones as far as I know, and this is why such trannies cannot handle the twist of a strong engine. Such trannies are found on the new A4 and the toyota pruis. however, there are probably other variations of the idea.
I do not know why they are banned in F1, probably just because. They would probably be quite expensive to put into F1, and would cut the lap times too much for Bernie's liking. I am not even sure if there had ever been an F1 car with a CVT. Besides, CVT equipped cars sound funny, and it would just be a shame to lose the sound of a speeding F1 car as it shifts in the high revs. mmmm... yummy!

As far as I Know, CVTs work by keeping the engine in the optimum rev range at any speeds, improving fuel consumption and efficiency. CVTs are banned because of what i suspect would produce a quantum leap in performance and additional parameters for engineers to play with. For example, there may be two seperate CVT maps for power or mileage. Computers may also produce seperate maps for each corner of the circuit, keeping the engine in the powerband throughout the whole lap...

Williams did some tests with the supplier of the cvt ( van doorne's transmissies)on an f1 car (1993 FW15c cvt) the results were positiv but the fia banned it for the 1994 season.

hugo is right, Williams did build a successful CVT for the FW15 in 1993.
As to how much improvement it was over the semi auto box i havent been able to find any details.... but didnt matter cause it got binned with all the other electronic aids in 1994.
Apparently the new develepmont gearbox in the MP-18 is using a twin clutch arrangement which is heading towards the benefits of CVT.

good article in the august issue of F1 racing about the supposed twin clutch transmission in the McLaren MP4/18A. The purpose of the twin clutch is to allow for quicker shifting times becasue the second clutch preselects the next gear before the first clutch disengages the previous gear. In theory, it should allow for faster shift times but with the added complexity involved along with a bulkier and heavier transmission, I am not sure if it is worth all the trouble.

yeah man.... that was a good lil article hey......also a good if somewhat short comparison between the MP-18 and the F2003GA by no less than Patrick Head in the last Formula 1 mag........
hope we get to see them race even if it is the last 2 races of the year..

well...I've been on holidays...and haven't bought the August issue of F1 Racing,.....but according to what you all wrote the system is quite interesting....but....(there is always a but)....I have a book that talks about the limits of gear shifting...but I left it at my other house and I'm only goiing back there in September!

So...I'll post back on this topic in September after checking the book!

sweet as monstro, let us know what the book is called too......
is it bout F1 tech or gearboxes in general?

the book is called F1 Technology, and it's written by Peter Wright (I think...I have about 30 tec books)....I remeber it mentioning something about gear shifting limits.....but I'll get back to you on that!

cool monstro, ill keep an eye out for it.........
which tech book on F1 is your favourite???

Welll...my favorite is F1 Tecnology....by Peter Wright, the other ones aren't so technical...they just talk about things so that the average person understands them....this book is easy to understand even for average people but it also has some more technical aspects.

...returning to the Mclaren gearbox....last night I finally bought the august issue of F1 Racing mag....and after reading about it.....and thinking a little about it...I believe that there is almost no limit in the gearshifting! The book I mentioned talks about convencional gearboxes...and the limitation in gearshifts is caused by the opening and closing of the clutch, and the movement of the dog-rings!....in the case of this new gearbox....the time that goes from one gear to the other is very small, cause the next gear is "pre-selected"so there's only a milisecond (or slightly more) between the passing from one gear to the other!

In the traditional gearboxes the clutch opened and the dog-ring would move (gear selection) and the clutch would close...... in this case....the only time lost is between one cluth de-clutching and the other one closing!

i will look out for that book monstro...... my favorite is the science of speed by david tremayne.... i used to collect the Ferrari F1 annuals but they stopped making them in 1997 which was a shame.....
yeah it does look good hey......i wonder if they have run it in the car at all as i know both boxes have been put on the dyno......

humm.....well if it works on the dyno....it works on the car....!

Just have a couple of doupts about double shifting.....nowadays you can shift from 5th to 3rd easily.....it takes the same tima as going from 5th to 4th.....because of the way the gearbox works.....but with the new gear box....if you reduce from one gear to another one that uses the same clutch....the gear selection process will be the same as in the old gearboxs....and this means....a whole lot slower....so....will the gearbox select the intermedium gear or will it jump from one to the other...???

Wow....

To read about the beginnings of the quick-shift gearboxes in its infancy was very nice...

Now, I wanna hear more about this CVT system!