Some cone CVT types use two rollers.[23][24] In 1903, William Evans and Paul Knauf used for just a patent with a continuously variable transmission applying two parallel conical rollers pointing in opposite Instructions and connected by belts that could be slid together the cones to differ the transmission ratio. Cause: https://gearboxcvt08539.ttblogs.com/12322661/what-does-gearbox-cvt-mean