Abstract: Variable speed ratio drive mechanism having a pair of opposed discs with facing dished surfaces and a spherical ball held between the discs and contacting said surfaces, each disc being rotatable to drive the other by frictional driving of the ball, one disc being movable so that its axis of rotation remains constantly angularly disposed relative to the axis of the other to effect variation in the distances of the points of contact of the disc surfaces with the ball to thereby effect variation of drive ratio of the mechanism.