Variable speed drive mechanism

A drive mechanism providing a speed ratio that is infinitely variable between predetermined limits, the mechanism comprising a casing, driving and driven shafts mounted to rotate in said casing about a common axis fixed with respect to said casing, driving and driven members respectively mounted for rotation with said shafts and respectively formed with frusto-conical friction surfaces facing one another for supporting a control sphere therebetween, at least one control sphere mounted between said surfaces in frictional engagement therewith, a circular rolling bearing assembly engaged by a portion of said sphere remote from said surfaces, said circular rolling bearing assembly having its axis passing through the centre of said control sphere, an adjusting member mounted in said casing for linear to-and-fro movement parallel to said axis, a control segment interposed between said rolling bearing assembly and said adjusting member, said control segment being formed with an arcuate surface on a side thereof remote from said rolling bearing assembly, said arcuate surface being centred on the center of said control sphere, said adjusting member being formed with a flat surface in contact with said arcuate surface, and said adjusting member and said control segment being formed with interengaging elements arranged for said arcuate surface to roll on said flat surface when said adjusting member undergoes said linear movement, and means for effecting said linear movement, thereby angularly adjusting said axis of said rolling bearing assembly with respect to said common axis of said shafts to vary said speed ratio.