Abstract: A locking device for a bevel gear differential having an insert (5) mounted on its own axis (4) which is also the axis of the planet bevel (3). The insert is situated between the opposing bevel gears (2) and has teeth (6) which engages with those of the bevel wheels and when the bevel wheels are displace relative to each other, the insert executes reciprocal motion along the axis of the pinion. Various ways of creating resistance in the motion of the insert is disclosed which limits the relative angular velocity of the bevel wheels as they rotate.