Oh, I know what you're talking about. I think that kind of transmission was first invented by a Dutch car manufacturer named DAF, later bought by Volvo. It's also used in snowmobiles and mopeds. I've seen it in industrial transmissions, but then in a manual version. I think the automatic ones use gravity, as the rpm's increase, a couple of spring-loaded weights pushes the sides of the pulley closer together, thus changing the ratio. Not very energy-efficient. I've driven one of those old DAF's, the Swedish Postal Services used to use them, and it's not a very smoothe ride.
