Some cone CVT models use two rollers.[23][24] In 1903, William Evans and Paul Knauf used for a patent on a constantly variable transmission making use of two parallel conical rollers pointing in reverse directions and linked by belts that would be slid together the cones to change the transmission ratio. https://travisiwhqy.sharebyblog.com/32571041/how-much-you-need-to-expect-you-ll-pay-for-a-good-gearbox-cvt