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The author


Marianne Guignard Fromont has been director during ten years of a company specialised in the production of shock absorbers, Incabloc S.A. located in La Chaux-de-Fonds/Switzerland.

3. The shock-absorber in the watch industry

Once in the past, whenever a watch had been dropped or suffered a shock, its owner would bring it to one’s ear with anxiety : was it still alive ? Very often, one could just realise that the balance-staff pivots were broken or bent. Then the precious thing was to be brought once again to the watch-maker for repair. How to protect such frail parts of a watch movement ? How to reinforce its heart ? These were the thoughts that kept many watch-makers busy, generation after generation. Indeed, as early as 1820, balance-staff protected by ‘parachutes’ were mentioned in documents referred to by the ‘Musée International de l’Horlogerie’ in La Chaux-de-Fonds. It is possible to trace back the fascinating evolution of the shock-absorber since the patents have started to be registered, that is in 1888.

An article written by Monsieur F. Glauser on behalf of Incabloc SA, producer of shock-absorbers, was edited in the ‘Bulletin SSC n° 25-1997’ of the ‘Société Suisse de Chronométrie’.
It illustrates a few of the outstanding discoveries on the matter. This article can be sent upon request (see herebelow address).
The “Dictionnaire professionnel illustré de l’horlogerie” gives the following definition of the shock-absorber as follow : “In a watch, a resilient bearing designed to damp the shocks that are brought to bear on the balance-staff pivots. Principle : the endstone is subject to the action of a spring. If an axial shock occurs, the endstone can lift slightly until the shoulder strikes a fixed part of the setting. To damp lateral shocks, the jewel hole is fitted in the setting comprising an inclined plane, which provides for a slight lateral shift limited by the collet-arbor or by the roller-arbor, which strikes a fixed part of the framework.”
Hereafter is one of the products currently used in the watch-making industry. It is the fruit of long years of improving and perfecting.
1. The spring holds and after a shock puts back in place the mobile element of the system
2. The end-stone of large diameter, lays inside the setting.
3. The hole-jewel is fitted into the self centering setting.
4. The block includes a double guiding-cone in which the double cone of the setting is adjusted.

When the intensity of a shock reaches the tolerable limit, the balance jewels ‘give’ under the thrust of the pivot. This recoiling movement continues until the resistant portion of the balance staff strikes against a surface which acts as a stop and absorbs the shock. As soon as the shock has been neutralised, the pressure of the spring brings the system back to its initial position. This recentring is effected immediately with absolute precision. However, the action of the spring is carefully adjusted : its dimensions and degree of tension are calculated so that it makes a selection between harmless shocks and those that may cause damage.
In the conditions in which the watch is normally used, the system is just as stable as a rigid bearing ( the reaction threshold is situated at about 35 grams). The diameter of this assembly generally varies between 1.5 mm and 2.1 mm and the height between 0.35 mm and 0.90 mm.
It is therefore easy to understand how skilful and meticulous the watch industry workers must be to produce and assemble such devices. The assembly is done manually for the smaller calibres, or with automatic machines for the larger ones. So as to guarantee the good functioning of the watch, it is necessary to lubricate the points of contact between the jewels and the balance-staff pivots.
The hole jewels and the end-stones are made of synthetic ruby. They go through an exclusive method of treatment which causes a real physico-chemical transformation of the very surfaces of the jewels. This process intensifies the retention of the oil, improves its cohesion and favours the formation of an extremely compact drop (angle of contact 30° instead of 10° or less ). This treatment resists to at least 8 energetic cleanings with detergents or solvents, and even with ultrasonic vibrations. The position of the jewels creates the conditions for perfect retention of oil. Their parallelism and their symmetry ensure rigorous centring of the oil. The distance between the end-stone and the hole-jewel remains constant. It is calculated to provide an optimum result. The oil reserve, contained in a dust-proof chamber, retains its lubricating properties for a long period of time.
The excellent quality of the jewels as well as the ‘olived’ shape of the hole of the hole jewel reduce the friction of the pivots to its absolute minimum. The balance amplitude therefore retains its high value in all positions, ensuring good and durable regulation. The blocks and the settings are profile-turned pieces, generally made in brass. They are then nickel or gold plated, sometimes also rhodium plated, according to the customers requests. The springs are blanked in a special steel and are nearly always gold plated.
The production of each of the pieces which form a shock-absorber, as well as their assembly, require a high level know how.
There are only few companies in Switzerland who have the capacity and knowledge to manufacture all or part of this watch component, a wonder of the world of micro-mechanics.




To obtain the above mentioned article :
Société Suisse de Chronométrie
c/o Centredoc
Abram-Louis Breguet 2

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