The TAG Heuer Monaco V4 Tourbillon, however, was even more of a challenge. A tourbillon, as many watch aficionados know, is a device that overcomes the effects of gravity on a movement by placing the balance wheel and escapement inside a rotating cage. Semon and his team added a new element to this system by using a micro-belt — thinner than a single human hair — to drive the tourbillon. The result, TAG claims, is no backlash on the tourbillon and a more fluid rotation of its cage. The timepiece is also equipped with an automatic, linear “railroad” rewinding system, as opposed to a more traditional swinging rotor. According to Semon, the four notched, micro-thin transmission belts (just .07 mm thick) provide an even more efficient shock absorption system than the gears they replace. The barrels, which hold a 40-hour power reserve, are held and rotated on ball bearings, another watch-manufacturing first.
The TAG Heuer Monaco V4 Tourbillon has a titanium case, with a black titanium carbide coating, that is slightly larger than that of the original V4, at 41 mm. It will be be delivered on a black alligator strap with a push-button folding clasp of the same material as the case. Semon assures us that this is not a concept watch; it is planned to go to market this year, with an estimated price of 150,000 Swiss francs.