Document 215039

History | 91
Watches &
How to protect a falling watch
In Breguet’s time, if you dropped your watch it would almost
certainly stop; one of the balance wheel pivots would have
broken and it would need repairing. The basic physics of the
watch movement make balance pivots especially vulnerable
to shock. Not only is the balance wheel relatively heavy,
with its weight concentrated at the rim, it is also the fastest
turning component in a watch. To reduce friction, its pivots
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.
The combination of weight in the balance rim and the thin
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.
(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:;