The invention relates to a movement transformation mechanism comprising a main planet gear (20); a planet carrier (30) which rotates together with said main planet gear (20); a ring gear (40) which is positioned at the continuation of said planet carrier (30) independent of the planet carrier (30) and which has at least an inner surface with a gear structure and a main planet gear (50) which is rotatably connected to the planet carrier (30) and whose thread is in contact with the thread on the inner surface of the ring gear (40) and whereon the rod arm (100) is hinged. In said mechanism, the diameter of said ring gear (40) is at least two times greater than the diameter of the main planet gear (50) provided that the diameter ratio is always an integer.