Toroidal variable speed traction drive

A toroidal variable speed traction drive comprising:

• a driving disc and a driven disc, said discs having a common axis of rotation, the inner face of each disc being formed with a negative shape of a toroid, such that inner faces of the discs define a toroidal cavity therebetween;
• a plurality of pairs of roller assemblies interposed between said discs, each roller assembly comprising a roller;
• wherein said discs are urged together against the interposed pairs of roller assemblies by a clamping force, wherein the rollers of each pair of roller assemblies are arranged to roll on each other with one roller contacting the driving disc at a first contact point and the other roller contacting the driven disc at a second contact point, wherein each roller assembly contacts each disc through a traction fluid at said first and second contact points, so that all the rotational force is transferred at said first and second contact points through said traction fluid;
• each roller assembly of each pair of roller assemblies being connected to a corresponding rotatable trunnion;
• each trunnion having a rotational axis which passes through the toroidal cavity;
• wherein by rotating each trunnion about its respective rotational axis each trunnion applies a steering force to its corresponding pair of roller assemblies at respective points relative to each roller assembly of the respective pair of roller assemblies;
• whereby the applied steering force causes the rollers of each corresponding pair of roller assemblies to rotate about a line that intersects the first and second contact points and to steer and adopt different first and second contact points with the discs;
• wherein each respective point at which the steering force is applied to each pair of roller assemblies is located offset from the corresponding trunnion rotational axis at a fixed distance and also is offset from the line which intersects the corresponding first and second contact points.