NECK CHAIN (SAUTOIR)

The Jumper (sautoir) is a spring whose end, in the shape of a beak or lens, rests against the toothed profile of a Star (wheel) or a Disc to ensure precise positioning in increments rather than through continuous movement. As the drive mechanism rotates the Star (wheel), the beak of the Jumper (sautoir) climbs the Flank of a tooth and gradually winds up the spring, without the Display moving; once the unstable equilibrium position is passed, the accumulated energy is released all at once, and the Jumper (sautoir) drops into the next notch, advancing the Star (wheel) by one step and holding it firmly in place until the next Release.

This principle, used everywhere a display must change instantly and remain strictly aligned, is found in the jump of the Date / Calendar at midnight, in instantaneous Day mechanisms, in the jumper of the Setting lever that positions and holds the Winding stem in each of its positions, or even in certain jumping hour displays. It should not be confused with the jewelry neck chain, a long chain worn as a pendant, whose name watchmaking has sometimes borrowed to designate pendant watches.