An octagonal case, a tourbillon movement with fusee-and-chain transmission and a pillar-based construction: the Chronomètre FB 1 has played a major role in defining the identity of Chronométrie Ferdinand Berthoud.
Calibre FB-T.FC powering this model is now preparing to take a last bow, in the form of a final 38-piece edition presented for the first time with a round case: the Chronomètre FB 2T.
The first contact: Winding
The first physical contact with a mechanical watch is when it is wound. Traditionally, this consists of manually winding the barrel. Equipped with a constant-force device known as fusee-and-chain transmission, Calibre FB-T.FC features a unique modus operandi, as winding is not done via the barrel, but by means of a differential placed in the centre of the fusee. This mechanism serves to reduce the force required for winding.
Seventy turns of the crown are thus required to fully arm the mainspring, smoothly and without the slightest effort. Its 9 mm diameter makes the crown easy to grip. It is also equipped with a safety device to protect the movement from excessive winding. A dynamometric spring hidden in the heart of this so-called "disengageable" crown makes it possible to limit the torque transmitted to the motor organ. When the tension required to wind the movement exceeds the permitted values, the dynamometric spring disengages, thus preventing the crown from driving the winding pinion. This prevents excessive winding which would damage the movement.
The motor organ: The choice of fusee-and-chain transmission
Activating the crown triggers the rest of the kinematic chain and invites observers to discover the various developments enabling each movement to be certified as a "Chronometer" by the Official Swiss Chronometer Testing Institute (COSC). With a mean daily rate of between -1 and +2 second(s) per day, the chronometric (precision timing) performance of Ferdinand Berthoud watches far surpasses the standards required by the COSC. To achieve such precision, the driving force of Calibre FB-T.FC calibre consists of an inverted fusee and a barrel – both suspended and linked by a chain ensuring constant force throughout the entire 53-hour power reserve.
The escapement: A tourbillon with central seconds
During the entire 53-hour power reserve, this constant energy is delivered to the escapement, a tourbillon with central seconds, for which a patent has been filed. Positioned at 6 o'clock, the tourbillon carriage engages directly with the seconds (fourth) wheel thanks to a wheel located on its axis whose diameter and properties are identical to those of the seconds. The two wheels thus make a complete rotation in 60 seconds: the seconds (fourth) wheel in a clockwise direction and the tourbillon wheel counter-clockwise.
Power-reserve indication: An unprecented mechanism
The power-reserve display of calibre FB-T.FC is based on a patented process that is as judicious as it is elegant.
Directly linked to the barrel by a large-diameter driving wheel, the mechanism uses the movement of arming and disarming the mainspring to move a cone up and down a threaded central arbor attached to the mainplate.
An invitation to experience bespoke: 38 customisable movements
Three versions will be offered by the Maison: FB 2T.2 in 18-carat rose gold with a black satin-brushed dial; FB 2T.2-1 in 18-carat rose gold with a ruthenium satin-brushed dial; and FB 2T.1 in 18-carat white gold with a blue satin-brushed dial.
These three references are sources of inspiration for collectors who will have the opportunity, for this "Final Edition", to create their own customised timepiece by choosing the case material, the colour and the finishing of the dial and the leather strap. There is however a limit with regard to the case shape: this FB 2T collection is offered exclusively with the round case presented in 2020 with the FB 2RE Remontoir d'Egalité collection.
