Variable speed transmission systems

Claim 1

A transmission system comprising two axially spaced rotatable torous discs rotatable about a common gear axis, part toroidal surfaces on the respective axially presented faces of the discs respectively, an input connected to one of the discs, an output connected to the other of the discs, a set of circumferentially spaced drive rollers in frictional rolling contact with the part toroidal surfaces on said discs respectively, bearing structures in which said rollers are mounted respectively, each of the bearing structures being tiltable through a ratio angle about an axis at right angles to an axis of rotation of each roller to vary the distances from the common gear axis of the discs at which the rollers engage the two toroidal surfaces of the discs respectively, means for moving the roller bearing structures generally tangentially with respect to the common gear axis of the discs, said means adapted for applying a force to said structures in a direction to vary a caster angle which is the angle of inclination of each roller with respect to a plane perpendicular to said common gear axis, and means for accommodating movement of the roller bearing axes relatively to said common gear axis of the discs, in a direction parallel with said common gear axis.