TAG Heuer Monaco V4 TourbillonIn 2004 TAG Heuer unveiled the MONACO V4 Concept Watch, the world’s first watch with belt drives, linear mass and ball bearings. The V4 name derived from the V-shaped main plate on which the movement’s four barrels are mounted: the 2-by-2 belt series on ball bearings are angled at +/-13 degrees, and look like the cylinders in a Formula One motor-racing engine.

In 2009, against all expectations, TAG Heuer stunned the watchmaking world by unveiling what many industry insiders said would never see the light of day: a fully commercialized production model of the MONACO V4. The breakthrough came as a result of five years of intensive research by TAG Heuer’s Haute Horlogerie engineers to overcome the last stumbling blocks—most important being the successful development of ultra-thin and ultra-resistant transmission belts.

Building on its top-secret development of transmission belts no thicker than a single hair, TAG Heuer takes its patented belt technology to the next level with with one of the most emblematic complication of watchmaking—the tourbillon. The result is TAG Heuer MONACO V4 TOURBILLON.

Tourbillon is a mechanical system for regulating the speed at which a watch beats. Traditionally, it overcomes the effects of gravity by placing the balance wheel and escapement inside a rotating cage. The TAG Heuer MONACO V4 TOURBILLON complicates this complication further, by using, in a world first, a micro-belt to drive the tourbillon. Thanks to the belt driving the tourbillon, there is no backlash on the tourbillon.

The major advantage is the absolute fluidity of its rotation. The timepiece is equipped with an automatic linear rewinding system, and the mass is guided by a linear railroad instead of a traditional rotating system. The four notched micro-thin (0.07mm) transmission belts, the design and engineering of which remain one of the best-kept secrets in watchmaking, create a very efficient shock absorbing system. In another first, the barrels are held and rotated on ball bearings.

TAG Heuer MONACO V4 TOURBILLON is entirely hand-crafted and assembled in TAG Heuer’s Haute Horlogerie workshop in La Chaux-de-Fonds, Switzerland. Its exclusive materials include space-grade black titanium for the case.