A mechanism (1) including a magnetic gear (2) including a first wheel (6A) and a second wheel (6B), the first wheel (6A) being provided with first permanent magnetic poles (7) forming first magnetic toothing (8), the second wheel (6B) being provided with a second magnetic toothing (10) made of a ferromagnetic material, the first wheel (6A) and the second wheel (6B) being arranged such that the first magnetic toothing has a first magnetic coupling with the second magnetic toothing (10). The gear (2) has a third wheel (6C) having second permanent magnetic poles (9) which form a third magnetic toothing (12), the third wheel and the second wheel being arranged such that the third magnetic toothing has a second magnetic coupling with the second magnetic toothing; the magnetic gear (2) being arranged such that the first and third wheels are each angularly positioned in a specific manner.