A. Lange & Söhne Cabaret Tourbillon
A. Lange & Söhne presents a delicate tourbillon mechanism set inside the Cabaret watch’s rectangular case. True to form, the manufacture’s watchmakers have given it a subtle but infinitely sophisticated twist: this particular tourbillon can be stopped and time set to the nearest second.
Peter Braun
For the craftsmen at A. Lange & Söhne, beauty is not enough. The company’s elegant wristwatches have always distinguished themselves with a technical refinement which, though small, often makes a considerable difference. These timepieces almost always conceal a mysterious and carefully considered mechanism whose advantages quickly reveal themselves to the proud owner of the watch in question. The new Cabaret Tourbillon is no exception to the rule.
Precision above all
Those with an interest in the watchmaker’s art know that the tourbillon was invented to make up for the effect of gravity on the movement’s rate, at a time when watches were carried in a waistcoat pocket and consequently in a constantly upright position. While today’s tourbillon wristwatches inspire the same devoted enthusiasm, they are also in the clutches of an identity crisis albeit brilliantly hidden by the power of fascination this high-precision mechanism continues to exert. Indeed, surprisingly few watchmakers boast of the foremost quality of their tourbillon, which is the extreme precision for which it was originally made. As recently as a few months ago, few buyers were deterred by the fact that a watch known for its rigorous precision could not be precisely set to an official time signal. Unlike a classic escapement chronograph, it was impossible to instantaneously stop and restart a tourbillon.
How to stop a tourbillon
This question, to which no answer had been found during the tourbillon’s two hundred-year existence, was a challenge which the talented watchmakers in Glashütte, Saxony, finally resolved.
First they decided against mechanically stopping the entire tourbillon cage. Taking this relatively simple approach would cause the balance wheel to slow down, losing amplitude and possibly coming to a complete halt. An outside force would then have to "kick-start" its to-and-fro movement again. The only viable alternative that would preserve the potential energy of the balance spring as it was stopped was to instantly and directly suspend the balance wheel’s movement inside the cage itself. This way, the balance wheel would immediately resume its oscillating movement as soon as the "brake" was released.
Easier said than done! How can the oscillating balance wheel be stopped inside the tourbillon’s revolving cage when one of the three cage posts gets in the way every 20 seconds? The problem had left specialists of the tourbillon escapement at a loss, until the engineers at A. Lange & Söhne finally found the solution… more than two hundred years after the ingenious device was invented.
When the crown is pulled, a complex mechanical motion brings a stop lever with two V-shaped spring arms into contact with the outer rim of the balance wheel, immediately causing it to stop. This action can be suspended if one of the V-shaped arms lands against one of the cage’s three posts. The delicate two-armed steel spring is therefore hinged at one of the brake lever’s rotation points. Hence even if one spring arm is resting against a post, the other will make contact with the balance wheel edge and stop it just as reliably as both arms would.
The asymmetric curve of the two spring ends was defined in a long series of tests. This special geometry ensures they exert optimal pressure regardless of the spring’s position in relation to the balance wheel. This curve also means the ends cannot accidentally engage when the balance wheel is stopped and released.
All is revealed
While the tourbillon is beautifully showcased through an opening on the dial side, it takes a trained eye to notice the curved ends of the blued steel spring. That the complication is suspended when the crown is pulled is of course immediately obvious, as will be the advantage of such an innovation to its owner. This patented invention finally makes it possible to precisely measure the improved accuracy of rate due to the tourbillon.
The Cabaret Tourbillon has other surprises in store: the twin barrel of the newly-developed manual calibre L042.1 has a power reserve of five days or 120 hours when fully-wound. The power-reserve indicator at 4 o’clock is visually balanced by the small seconds counter at 8 o’clock. The eye is also drawn to Lange’s signature large date, under the 12.
The movement, revealed through the sapphire crystal case back, is crafted to the highest technical and aesthetic standards, and finished with meticulous attention to detail. The painstakingly-decorated three-quarter plate in German silver is accentuated by six screwed chatons in gold. Three more chatons decorate the hand-engraved intermediate-wheel and tourbillon bridges, and the polished tourbillon bridge on the dial side. The pivots of the balance-wheel staff are suspended between two diamond endstones, reminiscent of the superlative 1A quality pocket watches once made by Lange. ■
