Abstract: A continuously-variable transmission includes two transmission members each having coupling elements engageable to couple the transmission members for movement together. At least one of the transmission members is a rotary member rotatable about a rotary axis; and at least one of the groups of coupling elements is radially displaceable towards and away from the rotary axis to change the conversion ratio of the transmission. The coupling elements of one group on one transmission member are of a fixed configuration defining projections alternating with depressions each of a fixed configuration formed on a surface of the transmission member between opposite side faces and having the same pitch for every cross section of the surface perpendicular to the mentioned rotary axis.

Abstract: A transmission system includes: first and second transmission members to be selectively coupled to each other or decoupled from each other. The first transmission member includes at least one gripping device having a plurality of spaced gripping elements, and the said second transmission member includes a plurality of coupling elements receivable in an interleaved manner between the gripping elements of the gripping device. The gripping elements of the gripping device being displaceable by a lateral compressive force (a) to displace them towards each other to firmly grip the coupling elements of the second transmission member and thereby to establish a non-slip coupling between the two transmission members; and (b) away from each other to decouple the two transmission members from each other.