With a host of multi-axis tourbillons on
the market today it's hard to find a starting point. So when JLC offered
me an opportunity for an insider view of their new Gyrotourbillon, I
accepted without hesitation.
In the beginning, the tourbillon was
designed to equalize balance wheel, hair-spring, and escapement errors in
the vertical positions by rotating the entire escapement approximately
once per minute in a singular axis. Now, with the advent of multi-axis
tourbillons, the escapement is rotated through both the horizontal and
vertical planes allowing yet another possibility in error correction.
The JLC Gyrotourbillon lives up to its
name as a true Grande Complication, having an inclined two-axis tourbillon,
perpetual calendar with instantaneous double retrograde indication,
equation of time, and 8-day power reserve with up and down indication.
The Gyrotourbillon (Gyro) is the
brainchild of Eric Coudray and designer
Magali Métrailler.
Their collaboration of engineering and design is cased in a modest sized
platinum package that is easy on the eyes and the wrist. Visually, the
complex mechanical attributes of the Gyro are presented in a mature and
natural way without being overly dramatic or busy. Internally, the
complexity is mind- boggling, having almost 600 parts and requiring a
totally new engineering direction from top to bottom. The Gyro will be
produced in a limited series of 75 watches, total, over the next 5 years.
In
this first installment of the Gyro I will concentrate on the tourbillon,
with details of other complications presented in future segments.
Note:
The watches and movements featured in this article are advanced prototypes
with some components more finished than others. The pictures were taken at
the bench at Jaeger-LeCoultre in Le Sentier as the watchmakers are
assembling, testing, and adjusting. These images are not fully
representative of the final product. In other words, these watches are
works-of-art, in progress.
Most
of the images below can be clicked to view larger versions. You will find links to very large versions of selected images at the end of this article.
Eric, the genius behind the Gyrotourbillon.
Concept and
execution.
Power is supplied via two mainspring
barrels, each fitted with sapphire covers on both sides. The sapphire
covers reduce mainspring drag and allow visual inspection of the
mainspring operation. The first barrel, lower right, is wound directly and
contains a short mainspring. The power from the first barrel is
transferred directly to the second barrel, lower left, via a great wheel.
This second barrel has a longer mainspring and acts as a simple remontoir.
Unlike most twin barrel configurations that have both barrels supplying
power directly to the center wheel in parallel, the Gyro barrel
configuration uses two barrels to create a linear flow of power with each
barrel spring maintaining control of the other, assuring ample but steady
power to the tourbillon.
Note: Since the tourbillon is inclined,
the 3rd wheel requires beveled teeth to mesh properly with the
tourbillon pinion. (Enlarge the above photograph for a closer look).
From the dial side we can see the beveled
3rd wheel "A" ready to supply power to the tourbillon, and the
beveled stationary wheel "B" that the inner escapement platform will
revolve around.
Shown above are the outer tourbillon cage
(left) and its end cap (right), with stationary 4th wheel, that
allows insertion of the inner escapement platform assembly. To improve
strength, threaded steel inserts are pressed into the cage where screws
are used. The outer cage is machined from a solid block of aircraft
quality aluminum to reduce weight, an amazing feat even with
computer-controlled machines!
Note: All tourbillons must be capable of
accelerating and decelerating the cage, as well as the escapement, more
than 5 times each second. This requires more power, and consistent power,
than a conventional stationary escapement watch.
Using modern materials, such as aluminum
and titanium is a great advantage compared to some early wristwatch
tourbillons since the effective mass of the cage is greatly reduced. The
weight of the Gyro's outer cage would be increased by more than 300% if it
were crafted from steel. Being aluminum, it weighs a scant 0.035
grams - about the same as a grain of dried rice!
The inner escapement
platform carries the balance wheel, hair-spring (balance-spring, pallet
fork (anchor) and escape wheel. It's pivoted at each end and is made from
titanium. Again steel inserts are used for screw holes to add strength.
Two views of the assembled tourbillon
cage. The picture on the left is the dial facing side, and the picture on
the right shows the opposite side with cage pinion that will mate with the
3rd wheel.
If you look closely at these pictures you
will notice two 14K gold screws on the outer cage and one on the inner
escapement platform that seem to have no purpose, but indeed they play a
very useful role in poising (balancing) the cage assembly.
The balance wheel and its adjusting screws
are made from 14K gold to increase the functional mass while in
oscillation (like having a much larger balance wheel made from a lighter
material).
Another point of importance, this
tourbillon uses only jeweled suspension instead of ball bearing races that
can easily be fowled by the smallest particle of dust causing stoppage.
Here we see the tourbillon cage assembly
installed in the movement. The outer cage makes one revolution per minute
and the inner escapement platform 2.5 revolutions per minute, making one
complete tourbillon cycle every two minutes.
A detailed drawing of the Gyro tourbillon
cage assembly:
Power is transmitted from the beveled 3rd
wheel to pinion "A" that is fixed to the outer cage "B". Wheel "D" with 40
teeth, fixed to the inner escapement platform, will follow wheel "C" with
100 teeth making 2.5 revolutions for each revolution of cage "B" (one
minute). Inner platform "E" will make 5 complete revolutions every 2
minutes.
Click here to view a video of the JLC Gyrotourbillon in action (40 mb)
