Some cone CVT types use two rollers.[23][24] In 1903, William Evans and Paul Knauf used for any patent over a continuously variable transmission making use of two parallel conical rollers pointing in reverse Instructions and connected by belts that can be slid alongside the cones to change the transmission ratio. https://gearboxcvt10752.tkzblog.com/32531724/a-simple-key-for-gearbox-cvt-unveiled