Since 2009 and the introduction of the Carl F Bucherer Calibre A1000, peripheral rotors are getting more and more in vogue. With this smart and stylish solution, the winding mass is an annular segment mounted and swinging around the movement, instead of a centrally mounted oscillating weight rotating over it. This offers an unobstructed view of the movement along with providing the convenience of automatic winding. In addition, peripheral rotors allow watchmakers to design thinner self-winding watches, without adding to their thickness with an oscillating weight rotating over the movement.

Carl F. Bucherer Manero Power Reserve Peripheral Rotor

Carl F. Bucherer Manero Power Reserve Peripheral Rotor

The calibre CFB A1000 series by Carl F. Bucherer – in 2009, it was the first movement with a peripheral rotor to be produced on a large scale.

The 1950s – First attempts

The idea of peripheral winding is, however, not exactly new. We can refer to a patent applied in June 1955 by Paul Gosteli of Geneva, (patent N° 322325 pictured below, filed on June 6th 1955, published on July 31st 1957) describing an original winding system for watches “characterized by an annular segment located around the movement cage”.

Peripheral Rotor – patent N° 322325, by Paul Gosteli

Similarly, some 10 years later, Patek Philippe also applied for a patent for a self-winding watch movement (patent CH 333587) with “a winding mass in the form of an annular segment… the mass and its associated gearing are disposed peripherally of the movement”. The brand would consequently manufacture the calibre 350. Among the various technical challenges, a traditional stem and crown could not be used because of the oscillating weight rotating at the periphery. Thus, the crown had to be mounted on the caseback side.

2009 – The comeback with Carl F. Bucherer

Carl F. Bucherer (CFB) has to be credited as the brand that brought the concept to modern serial production (2009), thanks to an efficient and convenient technical solution that includes a traditional crown and stem positioned at 3 o’clock – in short, where it usually is on 99% of the watches. Carl F. Bucherer’s concept relies on three small DLC coated rollers with ceramic ball bearings, driving the peripheral rotor. The ceramic ball bearings require no lubrication and winding is bidirectional: the rotor supplies energy when turning in either direction, thanks to two clutch-wheels with clamp rollers (based on friction).

Carl F. Bucherer implemented this smart concept first on the CFB A1000 calibre (2009), then on the calibre CFB A2000 (2016, an evolution of the calibre A1000, intended to be produced on a larger scale) and more recently on the calibre CFB T3000 with peripheral tourbillon regulator (2018) – all of them being entirely designed and manufactured in-house, in Lengnau.

Other applications

Following the development of the concept by Carl F. Bucherer, several other brands have implemented a peripheral rotor on their movements (mostly high-end) in recent years. For instance, Dewitt, Vacheron Constantin or Audemars Piguet. Peripheral rotors have also been instrumental in the creation of record-thin automatic watches. Late 2017, Piaget became the world record holder for the thinnest automatic watch. Powered by the calibre 910P, with its peripheral rotor visible dial-side, the Altiplano Ultimate Automatic is just 4.30 mm overall. The rotor is here positioned around the movement and mounted partially under the bezel – one of them multiple solutions that helped saving space on this watch.

Piaget Altiplano Ultimate Automatic 910P - Thinnest Automatic Watch

Piaget Altiplano Ultimate Automatic 910P - Thinnest Automatic Watch

Just a few months later, Bvlgari set two records in a single watch, the Octo Finissimo Automatic Tourbillon – the thinnest automatic watch and the thinnest tourbillon ever at just 3.95 mm. Thanks to the peripheral rotor, this self-winding movement is exactly the same height as the non-automatic version. It is just larger. However, Bvlgari’s watchmakers had to incorporate a pusher at 4 o’clock to alternatively set the time or wind the watch, as no stem could be incorporated (this would have blocked the rotation of the oscillating weight).

Last but not least, Cartier proposed another interesting – and artful – application of peripheral rotor winding. The peripherally-mounted oscillating weight of the calibre 9603 MC winds the movement and is shaped into beautiful designs brought to life in a clever way at every movement of the wearer’s wrist. For instance, the Rencontre de Panthères presented at SIHH 2018 features two Panthers that rotate as they seem to fight around a ring at the centre of the watch.

The peripheral rotor certainly is one of the greatest innovations found in recent years. While the micro-rotor and, even more, the centrally-mounted have been widely used since the 1950s, the advent of the peripheral rotor remains recent. Yet, more and more find grace in this stylish and technically satisfying solution. It combines many advantages: thinness, efficient winding (much more efficient than a micro-rotor, for instance) uncluttered view on the movement… With more and brands implementing the peripheral rotor, it would seem logical to see this solution soon applied to more “mid-end” watches, once brands have gained more experience on this concept. Still, Carl F. Bucherer has already proven that such technical content can be applied in watches at relatively reasonable prices. Credit where credit is due.


This post first appeared on Monochrome Watches - An online magazine dedicated to fine watches.