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!
