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SIHH 2017: A. Lange & Sohne - Tourbograph Perpetual “Pour le Mérite”

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The attribute "Pour le Mérite" is used by A. Lange & Söhne to indicate a timepiece whose movement is exceptionally complicated, one of the manufactory’s most elaborately crafted and precise calibres. It makes reference to the erstwhile Prussian order conferred for exceptional scientific merit.

Presented today at the Salon International de la Haute Horlogerie (SIHH) 2017 in Geneva, the new Tourbograph Perpetual "Pour le Mérite" is the fifth masterpiece in the A. Lange & Söhne’s series and combines the fusée-and-chain transmission with a tourbillon, a chronograph, a rattrapante function and a perpetual calendar. 


In October 1994, A. Lange & Söhne presented the first collection of the new era, including the legendary Tourbillon "Pour le Mérite", the first wristwatch with a tourbillon and a fusée-and-chain transmission. It was followed in 2005 with a further model in which these two elaborate constructions were united: the Tourbograph "Pour le Mérite". But there was more: a chronograph with the rattrapante function made it the manufactory’s most complicated watch at the time.

Now, the movement has been endowed with a fifth complication, the perpetual calendar.

Integrating such a sophisticated function to an already super-complicated movement presented the engineers of the Saxon manufactory with a tough challenge in preventing  mechanical conflicts or unwanted energy losses that could impact accuracy.

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, requiring a redesign of the basic calibre. At the same time, the developers did not want to noticeably increase the height of the movement.


The dial is purely classical: 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. 

Watchmaking tradition also governs technical details such as column-wheel control for the chronograph and rattrapante mechanisms as well as the screw balance. But is also manifests itself in quality elements such as the two diamond endstones that suspend the tourbillon cage or the black-polished tourbillon bridge. 


The platinum case with a diameter of 43 millimetres - thickness is 16.6 mm - safely houses the 684 parts of the new L133.1 manufacture calibre. Of these, no fewer than 206 constitute the perpetual calendar with its analogue displays.

The perpetual calendar 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. 


The three subsidiary dials indicate the date at 12 o’clock, the day at 9 o’clock, and both month and leap year 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. 

The third button on the caseband at 10 o’clock reveals that the Tourbograph Perpetual "Pour le Mérite" is not a standard chronograph but a split-seconds one. The fascinating function of the split-seconds mechanism can be observed in great detail with a look through the sapphire-crystal caseback. Two column wheels  precisely control the gold-plated chronograph hand and the blued rattrapante hand. 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 because of the technical challenge to manage power consumption when different functions are used, for example when the calendar indications advance around midnight and the stopwatch function is used at the same time. 

In the quest for the utmost precision, the tourbillon and the fusée-and-chain transmission contribute to improve rate stability and rate accuracy by offsetting gravity and waning spring force respectively.

The L133.1 movement 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. Beating at 21,600 vibrations per hour, it offers 36 hours of power reserve when fully wound. 


A detail that confirms the exceptional level of finishing is the black polish of the tourbillon bridge integrated in the dial shows a detail which confirms the exceptional level of finishing of this timepiece. In fact, the traditional black polish finishing technique is here applied, for the first time, to a curved surface.

The exceptional standards of Saxon watchmaking artistry are all remarked by other details visible on the back: thermally blued screws, screwed gold chatons, bridges and plates made of untreated German silver and decorated with Glashütte ribbing and perlage. The chronograph bridge is hand-engraved.


The fusée-and-chain transmission is responsible for delivering the force of the main-spring to the movement in constant increments thus compensating for the unavoidable torque loss of the mainspring barrel. This is performed via a fusée connected to the spring barrel with a chain. A planetary gearing mechanism inside the fusée assures that the flow of power from the mainspring barrel to the escapement is not interrupted while the watch is being wound. 

The A. Lange & Söhne Tourbograph Perpetual "Pour le Mérite" Ref. 706.025 will be produced in a limited edition of only 50 platinum-cased watches. The price is a bit less than half a million Euros. alange-soehne.com



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