Some cone CVT types use two rollers.[23][24] In 1903, William Evans and Paul Knauf used to get a patent on a constantly variable transmission working with two parallel conical rollers pointing in opposite directions and linked by belts that might be slid alongside the cones to range the transmission ratio. https://gearboxcvt87529.thezenweb.com/the-greatest-guide-to-gearbox-cvt-70691126