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Clock Gears


Pellaton's Pawl-Winding System

The ingenious automatic winding system of IWC Schaffhausen's in-house movements is a testament to horological innovation and engineering brilliance. Developed by Albert Pellaton over six decades ago and continuously improved, this remarkable system draws its power from the movements of the wearer's arm, keeping the watch running effortlessly.

At the core of this automatic system is a centrally bearing-mounted rotor, crafted from brass with an outer edge made of a heavy metal such as tungsten. Gravity and inertia play a vital role, forcing the rotor to move downwards with any positional error, resulting in continuous turning. Acceleration of the watch case generates torque at the centre of the rotor, which then winds the mainspring via a reducing gear. Pellaton's ingenious solution involves using an eccentrically bearing-mounted heart-shaped disc at the centre of the rotor instead of conventional ball bearings or cogs. This disc converts the rotor's revolutions into to-and-fro movements of a rocking bar. The rocking bar's motion is transmitted to the winding wheel through two pawls, expertly winding the mainspring efficiently and effectively.

Designing an automatic winding system presents several challenges for engineers. It must function seamlessly for wearers with diverse habits and lifestyles, while also withstanding significant wear and tear. In the new 52850 calibre, the rotor completes around 2600 revolutions to fully wind the two barrels, generating forces as much as 5000 times that of gravity during rapid movements. To protect the oscillating system, IWC turns to the use of technical ceramics, which are lighter, harder than steel, and incredibly resilient. The choice of technical ceramics is crucial, but its manufacturing is highly demanding due to the material's unique properties. During the sintering stage, the powder form of ceramic shrinks by around a third, necessitating precise manufacturing to achieve the desired tolerances. IWC, with its extensive experience in working with ceramics, has emerged as a leader in the industry in using these materials for movement components.

The breakthrough came when IWC successfully produced the 51900 calibre in zirconium oxide, reducing wear and tear. The next logical step was manufacturing the winding wheel in ceramic. After overcoming initial challenges and technological advancements, IWC now produces the automatic wheel and pinion as a single, integrated component in black ceramic, virtually eliminating wear and tear in the interaction with the pawls.

Up close shot of the IWC movement 52850

IWC Schaffhausen Big Pilot Annual Calendar Spitfire

The IWC Big Pilot Annual Calendar Spitfire is a true masterpiece of watchmaking, combining elegance, functionality, and precision. Its impressive array of functions includes a small hacking seconds, Pellaton automatic winding, and a rotor adorned with an 18-carat gold medallion. The sapphire glass, with its convex shape and anti-reflective coating on both sides, enhances legibility and ensures durability by being secured against displacement caused by changes in air pressure.

A notable feature of this timepiece is its annual calendar complication, which artfully displays the month, date, and day in three separate windows arranged in the American date format as a tribute to F. A. Jones, IWC's American founder. The annual calendar is intelligent enough to account for the varying lengths of months, requiring manual adjustment only once a year at the end of February. Two barrels provide ample torque to drive the three display discs, ensuring the watch's impeccable performance.

Housed in a robust stainless steel case with a substantial diameter of 46.2mm and a height of 15.3mm, the Big Pilot Annual Calendar exudes a sense of grandeur and sophistication. The screw-in crown ensures the watch's water resistance of 6.0 bar, making it versatile for various settings and activities. At the heart of this extraordinary timepiece beats the powerful 52850 Calibre, an IWC-manufactured automatic movement that is a testament to fine watchmaking. With an impressive power reserve of 168 hours and a frequency of 28,800 VPH (4.0 Hz), this movement showcases the meticulous craftsmanship of 326 components and 36 jewels, adorned with the exquisite Côtes de Genève finishing.


Available Now

The IWC Big Pilot Annual Calendar is a timepiece that embodies the essence of IWC's heritage and commitment to precision and innovation. With its blend of practical complications, impeccable design, and state-of-the-art movement, this watch is an exceptional choice for those who seek the ultimate in horological excellence. You can check out this stunning preowned watch below:

IWC Big Pilot Annual Calendar Spitfire in black and tan travel case


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