Shock protection is a spring-mounted holder for the jewel bearings of a mechanical watch’s balance wheel. It keeps the wheel’s fine pivots from being damaged when the watch takes a knock, such as a drop. The pivots and jewels are delicate for their load, so unprotected, they are a watch’s weakest point.
How does shock protection work?
In the Incabloc system, a lyre-shaped spring holds the jewel bearings. During an impact, the spring lets the bearings move in their settings. The balance staff can shift up and down as well as sideways, so the blow does not go straight into the ends of the staff. The movement stops when a sturdier shoulder on the staff comes up against the solid metal endpiece. That endpiece takes the force, not the fine pivots. To soften sideways shocks, the jewel sits in a chuck with a sloped surface.
Where it comes from
An early forerunner was Abraham-Louis Breguet’s pare-chute, dated to 1790. The name is French for parachute, as both are meant to protect against falls. In 1929 Fritz Marti received the first Swiss patent for a movable balance jewel. In 1934 he and Georges Braunschweig, both Swiss engineers, invented the Incabloc system. Before devices like Incabloc came into wide use, a broken balance staff was a common reason for a watch to need repair.
What other shock systems are there?
KIF Parechoc is the best-known alternative to Incabloc. Georges Galet founded it in Le Sentier, Switzerland, in 1944. ‘Pare choc’ is French for shock absorber or bumper. Other systems along the same lines include ETA’s Etachoc, Seiko’s Diashock and Citizen’s Parashock. Rolex developed its own system, Paraflex, in 2005. Today almost every mechanical watch has some form of shock protection based on the same idea as Incabloc or Kif.
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