A planetary gearing which includes a predetermined number of planet gears and a planet gear carrier with two walls on which the planet gears are mounted, supported by supporting pins defining a respective axis and the ends of which are fixed to a respective wall of the planet gear carrier, wherein each supporting pin is provided with, at an end thereof, an annular groove obtained in the thickness thereof, and wherein the groove has an extension along the axis lower than the extension of the meshing band of the planet gear along the axis. A ring may be provided partly inserted in the groove and having a profile equal to that of the portion of groove in which it is inserted. Such a ring acts as a mechanical stop for the yielding part of the pin which yields, under a predetermined load, up to a contact with the ring.