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Overcoming gravity: The Rotonde de Cartier Astrorégulateur watch Calibre 9800 MC

by Michael Weare
27 December, 2010
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About the author

Michael Weare has been a professional writer for 30 years, writing about Japanese technology, German and Italian cars, British tailoring and Swiss watches. Michael manages the editorial content of Click Tempus and will be keeping the magazine fresh and informative with regular features, as well as bringing great writers to the magazine. Email: michael@clicktempus.com

Cartier-rotonde-Astroregulateur-Calibre-9800-1

As you get older you learn to appreciate anything that can compensate for the laws of gravity, especially when you are in a vertical position.

The Calibre 9800 MC does exactly that, it’s a highly original movement that compensates for the effects of gravity on the timing mechanism in vertical positions.

With four patent applications, this movement is the fruit of five years of development within the Cartier Manufacture, where it was designed, developed, produced and assembled.

Compensating for the effects of gravity has always been one of watchmaking’s greatest challenges. Gravity disturbs what is known as the isochronism of a watch (the property of having a uniform rate of operation) by displacing the centre of gravity of its balance spring. Until now, the tourbillon has been the oldest and most common solution to this problem. The tourbillon carriage revolves on its own axis in one minute, passing through all possible centres of gravity. The tourbillon’s escapement averages out the errors, thus cancelling out any variations in rate that occur in the vertical positions.

Cartier’s ingenious solution to this problem is an innovative anti-gravity system using the only element that always returns to the same position in the vertical plane: the rotor.

In the 9800 MC Astrorégulateur movement, the escapement, the oscillator and the pendular seconds have been positioned on the rotor to maintain the centre of gravity in a single position.

By adjusting the oscillator in this one position the Astrorégulateur movement avoids the effect of gravity on timekeeping in all vertical positions.

During the course of an average day, your wrist moves in many directions and at differing speeds, subjecting the escapement to a variety of accelerations as the rotor spins. This unpredictable movement apply forces of various strengths on the entry lip of the escapement. These forces must be corrected in order to maintain the escapement at a constant speed.

The Astroregulateur is composed of two differentials that regulate the speed transmitted by the wrist to the micro-rotor into a constant speed, thus ensuring the regular advance of the seconds indicator that moves with the rotor and, therefore ensuring excellent timekeeping by the watch.

To make the micro rotor sufficiently heavy a platinum inertia block has been integrated so as to return to the same position and ensure the winding of the mechanism.

Limited to just 50 numbered pieces, the Astroregulateur comes in a large 50 mm case to showcase this exclusive movement. The niobium-titanium alloy reduces its weight to just 55 grams. Niobium-titanium also has optimal shock-absorbing properties, which convert any violent impacts into a softer shock charged with the same energy but released over a longer period of time and has a power reserve of 80 hours. It comes on a black alligator-skin strap with a double adjustable folding clasp in 18 carat white gold.

Michael Weare | Website

Michael Weare has been a professional writer for 30 years, writing about Japanese technology, German and Italian cars, British tailoring and Swiss watches. Michael manages the editorial content of Click Tempus and will be keeping the magazine fresh and informative with regular features, as well as bringing great writers to the magazine. Email: michael@clicktempus.com

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