Abstract: This invention relates to an automatic mechanical transmission apparatus with continuous variation of the transmission ratio from an infinite ratio up to a ratio less than 1/1, of the type employing centrifugal forces, comprising at least one driven plate bearing at least one continuous circular track, eccentric with respect to the common axis of the driving and driven shafts, and rollers which roll inside the circular track, being mounted to rotate about respective longitudinal axes, each of these rollers being borne by a rod connected to a pivot pin on the driving hub, characterized in that each rod bearing a roller is articulated on the outer part of a weight which is itself articulated on the hub fast with the driving shaft.