By the 1930′s the Swiss watch industry was coping with the demands of a growing audience for more “sport style” watches…those that could take more of a stressful existence. The result was several “shock” absorbing systems.
The most sensitive part of the watch is the balance assembly, this was where the innovators needed to look to solve the problem. As the watch took a shock..the balance wheel pivot had a tendency to “bounce” in the opposite direction of the impact…this sent the pivot up into the jewel and the cap jewel…often times cracking the jewel or actually breaking off the tip of the balance pivot…rendering the watch useless for timekeeping.
With the advent of the “shock-proof system”…the impact was absorbed. This was accomplished by placing a metal spring system over the balance jewels..this allowed the pivot and jewel to rise away from the balance plate thus absorbing the shock, and then to return back down to it’s original position.
In the picture, the jewel is in red, the cap jewel in pink…the pivot is in green, and the “incabloc” shock absorber is in gold. Picture is a Vintage BWC Chronograph Incabloc mechanism.