Abstract: This articulation comprises two coaxial annulus gears with internal sets of teeth (20, 22) of different pitch, one stationary and the other mobile, meshing with at least one planet (S1 to S4) bearing two external sets of teeth (24, 26) capable of mating with the internal sets of teeth (20, 22). The external set of teeth (26) that mates with the mobile internal set of teeth (22) extends over a shorter sector than the other external set of teeth (24), which means that the planet (S1 to S4) can move over a travel in which its two external sets of teeth (24, 26) are in mesh with the two internal sets of teeth (20, 22), between two end-of-travel positions beyond which the stationary internal set of teeth (20) is kept in mesh with the mating external set of teeth (24) while the other external set of teeth (26) is disengaged from the mobile internal set of teeth (22).