Abstract: A continuously variable transmission which has an input disc (40) and an output (45) defining a toroidal race (41, 46) and rollers (48) between the discs (40, 45), the rollers (48) being adjustable in unison to vary the transmission ratio by means of an internal operating member (51), and an external operating lever (59) which has a cam (56) determining the position of and having a non-linear relationship with a follower (55, 50) which is connected to the internal member (51).

Abstract: A roller drive system comprises two coaxial bevelled central rollers (32,32a) each coupled to a bevelled annulus (37) by way of a respective set of bevelled rollers (34,34a) each engaging the respective central roller and the annulus. The generatrices of the engagement surfaces of the rollers in each set and the annulus intersect at a respective common point on the axis of the central rollers. Hydraulic conduits (47,49,54) are provided for communicating hydraulic pressure in common to each roller to urge each roller axially into engagement with the surfaces of the central roller and the annulus.

Abstract: A toroidal race rolling friction transmission unit in which hydraulic actuators act upon most of the rollers to cause them to change ratio angle, but in which one of the rollers has a mechanical mechanism by which precise increments of ratio-change may be imparted. A hydraulic device senses the torque reaction of that roller, and is hydraulically linked to the actuators of the other rollers so that they are subjected to a force equal to the reaction force experienced by the mechanically-actuated roller. The hydraulic actuators may be in the form of two-step piston-and-cylinder devices, the actuating forces being exerted in one step, while a damping force is exerted in the other step.