continuously variable transmissions VERY cool concept

[mechanicalbrain]

all right i came across this in How Stuff Works.
http://www.chiefdelphi.com/pics/bin/112189449794.jpg
the cool thing is that there are no specific ratio it changes how you want it to. its powered by a main motor and then the two servos (A and B) change the position of the two adjustable gears changing from a high to low ratio. note my arrows are slightly off so here's another pic
http://static.howstuffworks.com/gif/cvt-17.gif
heres a link that explains more (http://auto.howstuffworks.com/cvt.htm) this type of transmission is more efficient than your standard gear change transmission. it even was in a couple cars for some time but just never got the publicity needed to make it in most cars. it has a smooth shift and you can have any gear ratio you want.

[Veselin Kolev]

The usual problem with CVTs is that they are friction based. You cant make those wheels out of gears, they have to be coated in some kind of traction. This means there will always be a limit to how much torque you can run through the system. I think that is the reason why CVTs never got around in the automotive world, they can only work well on small, low power cars. They were mostly used on cars like high fuel efficiency hybrids, which have lower powers anyway. But if you want a CVT on a big ol' SUV, youre gonna run into problems.

[ahecht]

This discussion should probably be continued over in this identical thread (http://www.chiefdelphi.com/forums/showthread.php?t=39028&highlight=cvt).