History | 91 Watches & Parachutes How to protect a falling watch A B D In Breguet’s time, if you dropped your watch it would almost certainly stop; one of the balance wheel pivots would have A broken and it would need repairing. The basic physics of the C watch movement make balance pivots especially vulnerable to shock. Not only is the balance wheel relatively heavy, B with its weight concentrated at the rim, it is also the fastest turning component in a watch. To reduce friction, its pivots C D are made as thin as possible, and to reduce wear the steel must be hard and therefore brittle. As the old joke has it: the fall is no problem, it is the landing that does the damage. E The combination of weight in the balance rim and the thin 4 brittle pivots of the balance staff is fatal when the watch hits Abraham Louis Breguet didn’t invent the parachute but he was the first to put his the floor. Breguet’s ‘parachute’ was a design which set the version into a watch. This may conjure up an image of the great French watchmaker balance jewel and endstone at the end of a flat spring allowing squeezing yards of silk into a watchcase – but it wasn’t quite like that. by the balance staff itself rather than the delicate pivots. it to move during shock so that the force could be absorbed Ahead of the times Timothy Treffry Apart from Breguet, no other watchmaker paid much attention to the shock resistance problem and, like Rip Van Winkle, The parachute, as a device for protection against a fall, have heard when, a couple of years later, Blanchard had to his idea slept for a hundred years. Shock resistance systems, has a long history; a version was used by an Arab daredevil use his invention in an emergency. Like Blanchard, Breguet at first referred to as ‘shock-proof’, were developed in the leaping from a tower in Córdoba in the 9th century Spain. was a great self-publicist. At a post revolutionary party 1920s and 30s but took a long time to become universal. In the late 18th century hot air balloons were all the rage given by Talleyrand for the great and the good, Breguet Well into the 1950s, replacing broken balance staffs in France. Breguet would probably have seen Jean-Pierre created a stir by first drawing attention to his new watch, remained a ‘nice little earner’ for watch repairers. They were Blanchard demonstrating a more modern form of parachute, throwing it to the floor, and showing that it still worked. themselves shocked when the famous Incabloc system, with the aid of a courageous dog, in 1783. He will certainly It was saved by a ‘parachute’. and its variants, became common. B A (Top) Rear view of the movement of Breguet No. 988, a ‘Souscription’ pocket watch. Sold in 1803, it has an early example the ‘parachute’ sprung balance jewel setting (see inset and diagrams) to protect the balance pivots if the watch is dropped. (Above) The parachute A fitted to a modern Breguet wristwatch, ‘Tradition’, produced in 2006. The drawings (adapted from George Daniels: The Art of Breguet), illustrate the construction and operation of the parachute. The endstone B and the balance jewel C , which form the bearing for the balance pivots, is mounted on a spring. Normally the balance staff is held centrally in the hole in the balance cock D . If the watch is shocked arrow), the parachute spring allows the jewelled pivot bearing to move as indicated and the balance staff E strikes the sides of the hole in the balance cock dissipating the shock. 92 | History History | 93 The systems described thus far performed satisfactorily in wristwatches with lever escapements and almost eliminated The Incabloc and Nivachoc systems balance pivot breakage. However, in 1999, when Omega introduced the Daniels coaxial escapement in a movement with Incabloc shock resistance, a number of owners had problems with erratic performance and intermittent stopping. For others however, the coaxial escapement has demonstrated superior long-term timekeeping to the traditional lever. But the coaxial does need to be made with much closer tolerances than the lever and cannot endure variations in the positioning of the balance staff. Flicker card promotional distributed to watch retailers in the 1970s. When viewed from different angles the card indicates the operation of the Incabloc system. Rather perversely it is the image on the left which shows the effect of a vertical shock, the shoulders of the balance staff press against the base of the Incabloc. The image on the right shows the normal running position. (Part of the British Horological Institute’s emphemera collection). In 2003/4 Nivarox FAR, a division of Swatch Group that makes the balances, balance springs and escapement components used by most Swiss watch brands, recently developed ‘Nivachoc’. This shock resistance system is said to reposition more precisely and reliably after shock. It first came to notice in 2006 when The Incabloc system, patented in 1933, is broadly similar to Breguet’s parachute in that the jewel and end stone for the balance pivot are positioned by a spring. In this case however, and in the many imitators who were to follow, the spring is a small circlip fitted over the setting for the endstone and balance jewel and pressing it into a conical cup. Under shock this setting will move with the pivot allowing the balance staff itself to strike against a collar that absorbs the shock. The spring should then return the setting to its original position. If it doesn’t, the performance of the watch may suffer. Shock resistance devices were never used in precision timekeepers such as Naval deck watches. It was felt that if the watch was dropped and its accuracy may had been compromised, it was better for it to be broken and replaced rather than be relied upon in life or death situations. An idea coming of age The Incabloc patent failed to protect its design. By the 1960s, the Bestfit catalogue, the watch repairers’ bible, listed nearly 50 shock resistance systems which, to a cursory glance, if not to a patent examiner, appear almost identical. The best known of these alternatives are the ‘Kif’ system used by Rolex, ‘Diashoc’ by Seiko and ‘Parashoc’ by Citizen. There was however a couple of interesting alternative approaches. In 1927 the Wyler watch company patented its ‘Incaflex’ design for an ‘unbreakable’ watch (‘incassable’ means ‘unbreakable’ in French, hence the use of ‘Inca’ in these trade names). The balance wheel has curved flexible arms and has very little clearance between its rim and the surrounding recess in the watch plate. When subjected to shock, the balance wheel will strike the watch plate, dissipating the energy and protecting the balance pivots, which retain their position. This design remains a feature of the present A 1960s advertisement for the Wyler Incaflex. The detailed view of part of the movement (with the balance cock removed) shows the flexible spiral arms of the Balance wheel. Note that the balance is closely surrounded by a cup fixed to the watch plate. If subjected to shock the wheel rim will tilt and its screw heads will touch the cup, absorbing the shock. The system was patented in 1927. new generation of Wyler watches following the revival of the company. A number of manufacturers of cheaper watches used it was used by Breguet (the company not the man) for its new self-winding movement, calibre 777Q. More recently its use was highlighted in the 8500 and 8501 movements for ‘Hourvision’, the latest star in Omega’s development of the coaxial escapement. Training material for ETA (the movement making division of Swatch Group) illustrates that, whereas repositioning in the Incabloc system may vary by 15–30 microns; the equivalent values for Nivachoc are 1–5 microns. This is attributed to differences in the design of both the setting and its spring. The subtleties of the interaction of spring, jewel setting and cup, which control the positioning of the balance staff in these traditional shock resistance systems have been avoided by a system revealed by Ulysse Nardin in September this year. The company has pioneered the use of new materials in watchmaking, particularly in the use of silicon for escapement components and even balance springs. In its latest concept watch, ‘Innovision’ (examined in more detail earlier in this issue) silicon has been used for a novel, one piece, shock resistance bearing, which may revolutionise the industry. Silicon components are made by etching and thus can be produced in exotic configurations that are not possible by conventional machining. The balance bearing in the Innovision watch consists of a silicon disc in which a central hub is held by The silicon shock resistance system, one of a number of innovations in the Ulysse Nardin ‘Innovision’. A hole in the centre, only seen from below, forms a bearing for the balance pivot. This is supported by 3 flexible spiral arms leading to the periphery. As in other systems the bearing will move in response to shock, in this case laterally. The shock will be absorbed by the spirals, and in severe shock by the balance staff, rather than the pivots. This system would be expected to reposition the balance arbor after shock more precisely than any other, given the symmetrical and integral arrangement of the springs. resilient spiral arms. This sprung-hub has a central blind hole acting as both bearing and endstone for the balance pivot. second flowering in the early 20th century as wristwatches Ulysse Nardin has cleverly designed the silicon disc to be pressed became more common. Following the unexpected renaissance into a ring that has the same external dimensions as the Incabloc of mechanical horology in the 1990s, a new generation of system, so the new technology is readily transferable to more watchmakers are opening their eyes to the possibilities of new conventional movements. technologies and new materials and beginning to apply them to making genuine improvements to the solution of a problem The development of shock resistance systems started in the that has been around for over 200 years. We seem to be on the literally ‘heady’ days around the French Revolution. It had a threshold of a new golden age of horological innovation. ‘Vibrax’ balance staffs. These have relatively long pivots, which were springy rather than brittle, enabling them to withstand shock. In the Nivachoc system the balance jewel setting (blue) sits squarely on its base (green). It is guided into position by the sloping sides but, unlike the Incabloc system, it does not come to rest on the conical surface. The view of the settings from above shows the design of the positioning springs (left, Incabloc; right, Nivachoc). The Nivachoc design is said to exert more symmetrical downward force. Further information: www.breguet.com; www.ulysse-nardin.com