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Bernhard Lederer is one of the earliest members of the Académie Horlogère des Créateurs Indépendants (AHCI) and founder of his eponymous company, Bernhard Lederer and his Universe (BLU) in 2002.
And today, he unveils his latest creation – the Central Impulse Chronometer, a three-hander wristwatch equipped with a natural escapement with dual geartrains – a tribute to the late George Daniels and his Space Traveller pocket watches, but with the evolution of having a remontoir d’egalité for each train.
It is not often we get presented with an interesting twist to an already uncommon escapement. In this case, Bernhard is making a statement of horological prowess by revitalizing the idea of the natural escapement, with the added complexity and benefit of a twin remontoir design. All of this is presented as an attractive, openworked movement with bridges made of maillechort, or nickel silver – albeit in a slightly large package of a 44mm diameter and 12.2mm thick case.
While the natural escapement is now less uncommon thanks to modern production methods, the Central Impulse Chronometer takes the elaborate approach by having two separate geartrains instead of one, which takes inspiration from George Daniel’s Space Traveller pocket watches. In fact, this makes it the second wristwatch of this writing that miniaturises Daniel’s solution – the first being the Charles Frodsham’s Double Impulse Chronometer.
Bernhard was particular with this design for several technical reasons. A natural escapement has two escape wheels – often powered by a single going train for convenience of space.
On paper however, this is not optimal as the two escape wheels have to be geared together, increasing their inertia and adding tight tolerance requirements to make it work. Having two separate gear trains addresses this issue by independently powering each escape wheel.
Special attention was paid to optimizing the escape wheels for low inertia. This ensures that they quickly contact the balance wheel roller on each swing, ensuring more efficient power transmission to keep the balance wheel oscillating.
Double constant power
Furthermore, the Central Impulse Chronometer has an extra trick up its sleeve – it has a ten-second remontoir for each geartrain, which provides a constant force to both escape wheels of the natural escapement. They are configured in an alternating setup, such that one remontoir can be seen and heard recharging every five seconds. This addition differentiates it from Daniel’s and Frodsham’s implementation of the standard double geartrains.
While appearing technically intimidating, the watch itself is simple to use as it works like any other three hander manual wind – winding the crown simultaneously winds both geartrains equally since they are mechanically linked. The barrels are wound via a beautiful crown wheel with an integrated triple click, providing very fine graduations of tactile clicks as the crown is wound. There is also no concern of overwinding the barrels, as they are allowed to slip on full wind, just like automatic watches.
An elaborate case
Not to be overlooked is the intricate case design. The case middle is unusually thin, with a highly domed sapphire for the dialside and caseback. This provides a notably wide, three-dimensional view of the intricate movement side. Interestingly, the design necessitates the movement to be installed via the dialside, unlike conventional watches with a removable caseback.
Two variants are available at launch – a rose gold case with a light grey dial dial, and in white gold with a partially openworked slate grey sunburst dial which reveals part of the movement. Due to the movement design, the sub-dial for the running seconds is located at an uncommon position between 7 and 8 o’clock, as the seconds hand runs off one of the symmetrical geartrains.
Key facts and price
Bernhard Lederer Central Impulse Chronometer
Diameter: 44 mm
Height: 12.2 mm
Material: 18k rose gold or 18k white gold
Water resistance: 30 m
Functions: Hours, minutes, seconds
Frequency: 21,600 beats per hour (3 Hz)
Power reserve: 38 hours
Strap: Alligator strap
Availability: 49 pieces
Price: 128,000 Swiss francs