A. Lange & Söhne’s “Pour le Mérite” series combines the fusée-and-chain transmission with a tourbillon, a chronograph, a rattrapante function and a perpetual calendar. The combination of these five complications makes the TOURBOGRAPH PERPETUAL “Pour le Mérite” a Bhanu-approved timepiece.

For 2017 the movement has been endowed with a fifth complication. In the development phase, the integration of a perpetual calendar in the TOURBOGRAPH PERPETUAL “Pour le Mérite” presented the engineers of the Saxony manufactory with a formidable challenge: to orchestrate the interaction of the complex mechanisms in such a way that mechanical conflicts or unwanted energy losses could be prevented. In this project, the perpetual calendar mechanism had to be built around the tourbillon. Consequently, only about two thirds of the movement surface were available, and this necessitated a redesign of the basic caliber. At the same time, the developers did not want to noticeably increase the height of the movement.

 43mm Platinum casing

The dial reflects the traditional approach in timekeeping. Arabic numerals, a railway-track minute scale, blued steel hands for the time and rhodiumed gold hands for the calendar as well as the cloverleaf arrangement of the subsidiary dials pay tribute to the famous A. Lange & Söhne pocket watches. Tradition also governs technical details such as column-wheel control for the chronograph and rattrapante mechanisms as well as the screw balance. two diamond end stones that suspend the tourbillon cage or the black-polished tourbillon bridge.

 Perpetual calendar

Of the 684 parts of the new L133.1 manufacture caliber, no fewer than 206 constitute the perpetual calendar with its analog displays. It will correctly indicate the duration of each month until 2100. A one-time correction will be needed on the last day of February in this secular year. From then on, the calendar will again be correctly calibrated for the next hundred years. It has three subsidiary dials. The date at 12 o’clock and the day at 9 o’clock are indicated with rhodiumed gold hands.

The month and leap year are both displayed at 3 o’clock. The upper half of the analogue date also accommodates the moon-phase display which is calculated to remain accurate for 122.6 years. Its deep-blue disc is made of solid gold. During the development of the calendar module to be built around the tourbillon, great emphasis was placed on space-saving architecture.

Chronograph with rattrapante function

The function of the split-seconds mechanism can be observed in great detail with a look through the sapphire-crystal caseback. The precise control of the gold-plated chronograph hand and the blued rattrapante hand is handled by two column wheels. During a complete revolution of the 30-minute counter at 9 o’clock, as many lap times as needed can be stopped.

The combination of a perpetual calendar with a split-seconds chronograph is very rare. Power management is an especially challenging undertaking. In particular, the simultaneous use of several functions calls for mechanical ingenuity, for instance when the calendar indications advance around midnight and the stopwatch function is used at the same time. Assembling such a movement requires considerable experience and exceptional sensitivity when adjusting and harmonizing the mechanisms.

One Minute Tourbillon

The L133.1 move-ment that works inside the TOURBOGRAPH PERPETUAL “Pour le Mérite” is already the tenth calibre with the delicately linked mechanism that overcomes the pull of gravity. The tradi-tional black polish of the tourbillon bridge integrated in the dial imposes new challenges on the finisseurs because for the first time ever, this complex finishing technique is being applied to a curved surface.

Fusée and Chain Transmission

The fusée-and-chain transmission was integrated in a wristwatch for the first time in 1994. It is the technical hallmark shared by all timepieces identified by the attribute “Pour le Mérite” in reference to the Prussian order conferred for exceptional scientific merit. Via a fusée connected to the spring barrel with a chain, the force of the main-spring is delivered to the movement in constant increments thanks to the ingenious way in which the principle of levers is harnessed. The filigreed yet robust mechanism requires the utmost in attention as regards design, production, finissage, and assembly.

The TOURBOGRAPH PERPETUAL “Pour le Mérite” is being crafted in a limited edition of only 50 platinum-cased watches. The finish of the manufacture caliber complies with the highest standards of Saxon watchmaking artistry. Thermally blued screws, screwed gold chatons, bridges and plates made of untreated German silver and decorated with Glashütte ribbing and perlage as well as the hand-engraved chronograph bridge round out the highlights of this classic complication.

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