tourbillon

A tourbillon is a rotating escapement mechanism used in mechanical watches to reduce positional errors due to gravity. It was devised by Abraham-Louis Breguet around 1801. The mechanism places the escapement and balance wheel in a rotating cage, which constantly changes positions relative to gravity.

In a typical tourbillon, the escapement, escape wheel, pallet fork, and balance wheel are mounted inside a small carriage that revolves around its axis, usually once per minute. By continuously rotating, it averages out rate variations caused by gravity when the watch is kept in different orientations, thereby improving accuracy on static tests.

Variants include the flying tourbillon, where the cage is mounted without a bridge above the balance, giving the appearance of a floating cage; and multi-axis tourbillons, which use two or more axes of rotation to further reduce positional errors. The carrousel is a related mechanism that also aims to improve accuracy by rotation but differs in construction.

In modern horology, tourbillons are widely associated with high-end watches and craftsmanship. While they can provide measurable accuracy benefits in some conditions, many modern wristwatches rely on other technologies and tolerances, and tourbillons are often valued for aesthetic appeal, mechanical ingenuity, and prestige.

Notable makers and examples include Abraham-Louis Breguet (originator), Patek Philippe, Jaeger-LeCoultre, Audemars Piguet, Vacheron Constantin, and Greubel Forsey, among others. The tourbillon has become a hallmark of luxury watchmaking and a benchmark for technical prowess.