Tourbillon (French for whirlwind)
The ingenious inventor Abraham-Louis Breguet had the idea (1801 patented for him) to neutralize a cause of inaccuracy, namely the influence of gravity on the centre of gravity of the balance, through a special device. Here escape wheel, lever and balance wheel are placed on a small plate in a so-called bogey, a cage sitting on the shaft of the seconds wheel. As the seconds wheel turns, now also the bogie itself turns once per minute (hence also: minutes tourbillon), so any position or centre of gravity errors are compensated.
Due to the high accuracy now also reached by usual mechanisms the tourbillon is now just a highly exclusive luxury addition. However, he is regarded as the summit feature of exceptionally valuable watches.
In the 1920s, Alfred Helwig, specialist subject teacher at the German Watchmaker School Glashütte, invented the Flying tourbillon, which in contrast to the simple tourbillon is suspended only one-sided.
One issue with tourbillon movements is the difficulty in implementing a hacking or "stop seconds" feature. Because the escapement is in constant motion, it is difficult to position a lever to stop it. It was not until 2008 that A. Lange & Söhne implemented a stop seconds feature on a tourbillon, and 2014 when the same company added a zeroing feature.
Tourbillon vs. Carousel
- See also Carousel
A similar mechanism is the carousel which uses a gear to drive the rotating balance and escapement, typically attached to the fourth wheel. In contrast, a true tourbillon rotates on its own on its bogey. Because they appear and function similarly, carousels are often called "tourbillons" by unsophisticated commentators.