Peripheral rotor
A peripheral rotor automatic movement places the weight segment used to wind the watch on a track outside the movement itself.
Overview
The peripheral rotor turns outside the movement, though typically still on the plate. It interacts with gears set into the side of the movement to wind the mainspring. This is in contrast to a central rotor movement, which mounts a full-width weight segment on a bottom-mounted bearing at the center, and micro-rotor which uses an integrated, smaller weight segment inside the movement.
This unique design allows the entire movement to be viewed through a display caseback and allows the company to install modules on both sides if needed. One challenge of a peripheral rotor system is the location of the stem and crown: Patek Philippe mounted these to the back of the movement, while the Carl F. Bucherer movement was thicker, allowing a traditional side position.
History
Peripheral winding took many years to come to market. The concept was first patented in 1955 by Paul Gostel but did not reach production. A similar design was patented in 1965 by Patek Philippe and came to market in 1970 in limited production as Cal. 350. However Cal. 350 was widely regarded as unreliable, even after an update in 1979 with uni-directional winding. The entire series was retired in 1985.
Citizen also produced a variation on the peripheral winding theme with their Citizen Jet of the 1960s, but this was more of a geared central rotor and did not run around the periphery of the movement.
Cal. CFB A1000, introduced by Carl F. Bucherer at Baselworld 2008 after three years of development, was the first mass-produced peripheral rotor movement. The new manufacture developed many new technologies to bring the peripheral rotor to production, as well as a shock protection system for the balance spring carrier stud. The first watch to be produced with Cal. CFB A1000 was released for sale in 2009, by which time other manufacturers were working on similar technology. De Witt would introduce Cal. DW 8014 in 2010, Audemars Piguet would follow with Cal. 2897 in 2011, and Cartier with Cal. 9603 MC in 2012.