The story of shock resistance in watchmaking is, in many ways, the story of the wristwatch itself — because the wristwatch would never have become viable without solving a problem that the pocket watch had never needed to face.

A pocket watch lives in a controlled environment. It moves when its owner moves, rests when he rests, and the most significant shock it typically encounters is being placed on a hard surface. The pivot of a balance staff — the finest, most fragile component in a mechanical movement, measured in hundredths of a millimetre — can be made extremely delicate precisely because it is rarely asked to absorb an impact.

A wristwatch is strapped to a human wrist. It is subjected to the full mechanical violence of daily life — doors, desks, sports, falls, gestures. The same pivot that worked perfectly in a pocket watch snapped with regularity in early wristwatches, which is one of the reasons the format was initially dismissed by serious watchmakers as a passing fashion unsuitable for precise timekeeping.

The first systematic thinking: Breguet and the “pare-chute”.

Abraham-Louis Breguet, working in Paris in the late eighteenth and early nineteenth century, was the first to address the problem at a fundamental level — and he did so entirely within the artisanal tradition of his time. Every watch that left his workshop was made by hand, by skilled craftsmen working to individual specifications. The concept of standardised industrial production did not yet exist — it would not reach the watch industry for another fifty years, when the mechanisation of the Swiss Jura valley and the influence of the American system of interchangeable parts would transform how movements were made.

His parachute system — patented in 1790 and refined through the following decade — mounted the jewel bearings of the balance staff in small resilient arms rather than rigid settings. When a shock was transmitted to the movement, the arms flexed and absorbed the energy before it could reach the pivot. The staff would deflect slightly, the arms would spring back, and the pivot would survive intact.

The parachute was elegant, effective, and entirely dependent on the skill of the individual craftsman fitting it. It appeared in Breguet’s most important commissions and never reached anything resembling series production. But it established the conceptual framework that all subsequent shock protection systems would follow, more than a century later, when the tools to industrialise that framework finally existed.

The industrial problem — and the industrial solution.

The mass production of wristwatches in the early twentieth century made shock resistance an economic problem as well as a technical one. A system that required individual hand-fitting was incompatible with factory production at scale. What the industry needed was a shock protection device that could be manufactured to consistent tolerances, fitted without individual adjustment, and replaced when worn.

The solution arrived in 1933, developed by Fritz Marti at the Swiss firm Porte-Echappements Réunis and commercialised under the name Incabloc. The system was conceptually simple and mechanically brilliant: the jewel bearing was mounted in a small setting held in place by a spring shaped like a lyre. Under normal conditions, the spring held the jewel precisely positioned. Under shock, the jewel could move in any direction — lifting, rotating, deflecting — absorbing the energy of the impact. When the shock passed, the spring returned the jewel to its precise position, ready for normal operation.

Incabloc was not the first industrialised shock protection system — Kif, developed in Switzerland around the same period, offered a similar solution with a different spring geometry — but it became the most widely adopted, appearing in hundreds of millions of movements from nearly every Swiss manufacturer across the following decades. The name became so associated with shock protection that it functioned almost as a generic term.

The key innovation was not the spring itself but the precision of the return. A shock protection system that absorbed impacts but left the jewel slightly misaligned after each event would degrade timekeeping progressively. Incabloc’s lyre spring returned the bearing to within microns of its original position, consistently, across thousands of shock cycles. This is what made it suitable for mass production — the tolerance was built into the geometry of the spring, not into the skill of the watchmaker fitting it.

The American exception: Timex and the philosophy of robust imprecision.

The Swiss approach to shock resistance was fundamentally conservative: protect the delicate pivot by allowing controlled movement, then return it to its original precision position. The goal was to maintain accuracy despite the shock.

Timex, working in Middlebury, Connecticut from the 1950s onward, approached the problem from a completely different philosophical position. Rather than protecting a fragile pivot, Timex designed movements in which fragility was simply eliminated.

The key innovation was the substitution of conventional cylindrical pivots with conical pivots that ran directly in the plates of the movement without separate jewel bearings. A conical pivot distributes stress along its entire taper rather than concentrating it at the tip. It is more resistant to shock by geometry, not by protection system. The trade-off was friction — conical pivots running in brass plates generate more friction than jewelled bearings — which meant reduced accuracy and shorter service intervals. Timex movements ran at lower frequencies than Swiss equivalents and were less precise in their rate.

But they did not break. A Timex could be dropped, banged, subjected to treatment that would destroy a conventional pivot, and continue running. “Takes a licking and keeps on ticking” was not a creative invention but a precise technical description. Timex demonstrated their watches being attached to outboard motors, strapped to hockey sticks, subjected to deliberate abuse on television, and surviving.

The philosophical difference is worth stating precisely: Swiss shock resistance was designed to protect precision. Timex shock resistance was designed to replace precision with durability as the primary value. These are not the same goal, and they produced genuinely different objects — one optimised for accuracy that could survive reasonable abuse, the other optimised for survival that sacrificed some accuracy to achieve it.

Both solved the problem of the wristwatch’s vulnerability. They solved it for different customers, at different price points, with different definitions of what a watch was fundamentally for.

The Incabloc spring and the conical Timex pivot are, in that sense, the two poles of an argument about watchmaking values that the industry is still having today — between the Swiss tradition that treats precision as non-negotiable and the American tradition that treated durability as the primary commercial virtue.

Breguet identified the problem in 1790. The tools to solve it industrially arrived fifty years after his death. The argument about how to solve it is still running.