Abstract: A new scissor-ramp mechanism for a Continuously Variable Transmission (CVT) provides smooth transmission of variation to the width of the groove for the V-belt of the CVT. The scissor-ramp mechanism consists in driving rings that are coaxial, concentric to each other, and rotatable relative to one another, each having a driving abutting facet; and a driven ring having driven abutting facets. The driving abutting facets are adapted to abut against the driven abutting facets, with at least one abutting facet being provided by a helicoidal ramp. Rotating the driving rings relative to one another exerts a contacting section of abutting facets to migrate over the ramp, thereby changing the axial dimension of the scissor-ramp mechanism.