The Extroid is obviously a revolution. Instead of using a belt or chain as the media for varying transmission ratio, it uses two pairs of rollers. This system is based on the idea of the friction cars built in the years 1860 till 1905.
In 1877 Charles Hunt acquired the world's first patent for the Torodial CVT, a transmission for use in the general industry. The change in speed between the input and output shafts is managed by changing the angle of the roller between the two discs. The difficulties with this system lay in the enormous amount of friction between the roller and the discs causing the discs and the roller to wear out very quickly.
In 1963 Curtis Wright Corp. in the USA began research on a half Torodial CVT for use as an automotive transmission, but the project never got of the ground. In 1973 Mr. Krauss at Excellamatic Inc. of the USA, tested a Torodial CVT in a Ford Pinto but that lasted just 1200 kms.
In 1978 NSK began research on this CVT for use in automobiles. After much research they made their first test drive in 1983. Together with Nissan they have developed a CVT that can withstand a high torque and is to be called the "EXTROID CVT".