824,803. Continuously variable friction gearing. KOPP, J. E. April 30, 1957 [July 7, 1956], No. 13684/57. Class 80 (2). A continuously variable friction drive in which friction rolls with double conical surfaces have their axes of rotation at an angle to the common axis of the running surfaces between which the rolls are arranged and in which the transmission ratio is varied by movement of the rolls in the direction of the axis of the running surfaces, is characterized in that the conical circumferential surfaces of the rolls are inclined to the axis of the running surfaces which are staggered to each other in the direction of their axes. Input and output shafts 3, 4 are in driving relation with discs 9, 10 through camming ball devices 11 such that torque between the shafts and the discs produces axial force on the discs to increase their engaging pressure on a series of double conical rollers 7. The rollers are journalled at 8 in a non-rotatable cage 6 movable along the axis of shafts 3, 4 by a rack and pinion mechanism 15, 16 to change the transmission ratio. The surfaces of the conical portions of the rolls 7 are arranged at an angle to the axis of the shafts 3, 4 such that the bearing pressures of the rolls produced by the contact pressure are partially compensating. In a modification, Fig. 3, the rolls 7 are carried in a cage 22 in driving connection with a shaft 31 and axially movable by a rack and pinion mechanism 26, 27. The rolls are contacted by a rotatable disc 10 having a camming ball drive with shaft 4, and by a stationary disc 28 in camming ball relation with the casing 20. Embodiments are described in which a plurality of gears according to Fig. 1 are arranged in parallel and in which a gear according to Fig. 1 and a gear according to Fig. 3 are arranged in series. In a further modification, Fig. 6, the rolls 43 are journalled in a carrier 45 by roller bearing 44, and engage a ring 48 splined to the casing 51 and axially urged by a spring 52. The carrier 45 is rigid with one drive shaft and a disc 47 with the other drive shaft 46.