Bernhard Lederer, the award winning independent German master-watchmaker based in Switzerland, presents Central Impulse Chronometer that also marks the maestro’s return to the independent watchmaking arena.
One of the first members of the AHCI (Académie Horlogère des Créateurs Indépendants), Bernhard Lederer is a self-taught watchmaker who has introduced numerous breakthroughs in traditional watchmaking craft. He has created a number of outstanding mechanical watches including some extraordinary tourbillons.
The Bernhard Lederer Central Impulse Chronometer belongs to a new collection entitled ‘Tribute to the Masters of Escapements,’ a limited series of precision chronometers designed and developed to honor the masters who set true milestones in the advancement of an horological invention that remains as crucial and fascinating as ever.
The Central Impulse Chronometer by Bernhard Lederer is a lustrous, puristic looking three-hand watch driven by a complex movement equipped with a world-premier natural escapement, which is a result of unimagined development efforts and a testament to the noblest of legacies.
Escapement is one of the most complex and noble subjects in watchmaking. The Central Impulse Chronometer timepiece incorporates an advanced mechanical escapement that follows the principle of the natural escapement with two 10-second constant-force mechanisms as conceived by John Harrison in 1756.
Drawing on nearly 40 years of experience and the resources of his workshop in St Blaise near Neuchâtel, Bernhard Lederer completed the work on the natural escapement initiated by George Daniels, who himself had taken over where Breguet left off.
The Central Impulse Chronometer escapement is the ultimate, reliable and stable embodiment of the mechanical movement’s counting and regulating system designed by the English watchmaker. It is composed of two escapement wheels operating in alternation and connected to an anchor that is absolutely one of a kind. To achieve the precision of his Caliber 9012, Bernhard Lederer installed these two escapement wheels at the end of two separate gear trains, each with its own barrel and its own 10-second constant force remontoire.
In finely stabilizing the driving force, optimizing the geometry of the escapement parts, paring down the weight of these energy-intensive components, and reducing the internal friction of the escapement to a minimum, Bernhard Lederer has achieved an extraordinary degree of watchmaking perfection.
The Central Impulse Chronometer watch has a sleek, understated round case in rose or white gold and a smooth bezel. The rose gold version features a vast, minimalist dial with a small seconds at 8 o’clock with a circular finish. For those who prefer a more visible technicality, Bernhard Lederer offers a second version in white gold with a slate grey sunburst open-worked dial.
About Bernhard Lederer
Bernhard Lederer is a German watchmaker born in 1958 and largely self-taught. He had been working in the field of floor clocks, monumental clocks and wristwatches since well before the end of his apprenticeship as a watchmaker. Without ever having learned under a great master, without a technical mentor as such, he developed a culture of quality, driven by what can only be called a true inner fire for watchmaking.
Trained on the job, spurred on by a deep passion for watchmaking and a penchant for technical challenges, he began his watchmaking apprenticeship at the Wuppertal Watchmaking Museum, then in Pforzheim, building a parallel career as a watch repairer and restorer. His masterpiece, completed at the age of 25 to qualify as a Master Craftsman, was a table clock. It had a gravity escapement with a perpetual calendar that solves the problem of non-leap years that are multiples of 400, with a synodic and sidereal moon display accurate to 800 years and a solar and lunar eclipse display. When the AHCI was founded in 1985, he was invited to become one of its first members.
A technician and practitioner of watchmaking in all its aspects, Bernhard Lederer early on turned his attention to escapements. In 1986 he rebuilt the gravity escapement that was the hallmark of William Bond & Sons, Boston, Massachusetts. Working entirely on the basis of period documents, he managed in the process to solve all the intrinsic problems that undermined the reliability of the very high-performance chronometer escapement invented by Richard F. Bond in the 1860s. It was a few years earlier, while educating himself in watchmaking, that he discovered George Daniels’ books, Watchmaking and The Practical Watch Escapement. Not finding them anywhere in Germany, he hitchhiked all the way to London. This would be his first contact with the already legendary watchmaker, himself the inventor of several escapements.
In 1996, he spent more than a year in Brazil to finalize the iconic Brazil Monumental Countdown Clock. During this period, he also created the Time Dimension, an avant-garde wristwatch with a black case and a time display complication using concentric circles devoid of markings.
In 2002, a collection of wristwatches was launched under the BLU brand – for Bernhard Lederer and his Universe. Here, Lederer’s aesthetic sensibilities came to the fore in watches that were instantly recognizable by the single lug and smooth round cases housing off-center display complications, with the characteristic hands that were his signature at the time. His most striking creations were in the field of orbital tourbillons: Majesty Tourbillon MT3, followed by Tourbillon Gagarin, which won numerous awards throughout the world.
In 2014, he returned to his workshop, collaborating with a historical expert to compile a matrix of all known escapement systems. It is on this foundation that he began work on several approaches, including the Central Impulse Chronometer. In 2016 he presented a movement entirely of his own design with the highest magnetic interference threshold ever achieved. Rated to 100,000 Gauss and certified NATO-STANAG 2897, it emits a magnetic signature of less than 5 nanotesla. This was the criterion for passing muster with the mine clearance divers unit of Germany’s NATO Special Forces, whose lives depend on utterly non-magnetic equipment.
About Dr. Georg von Tardy
Dr. Georg von Tardy had trained as an aerospace engineer at the University of Stuttgart before joining Porsche in 2002. There, he worked on their chassis but notably also developed steering and control systems. The racing cars so equipped garnered victories in endurance world championships and a win at Le Mans. A watchmaking autodidact, he developed a keen interest for the work and research of George Daniels.
As he began exploring the world of watch calibers, building models and hatching ideas for constant-force escapements, Georg von Tardy discovered his true passion. When he met Bernhard Lederer in 2012, his interest in watchmaking only intensified. Naturally, the conversation turned to the subject of escapements. They decided to keep in touch, regularly engaging on a path of thought and exploration into their common passion. This friendship eventually led to the creation of Central Impulse Chronometer.
The escapement is essentially the watch’s internal system for counting the passage of time. On one side, a barrel supplies energy to the gear train, without any regulation. On the other, a balance wheel, aided by the regulating balance spring, oscillates at a rhythm that must be as regular as possible. Between the two, you have the escapement which is situated as closely as possible to the balance-wheel so that its oscillations can be registered and the energy from the barrel transmitted to it.
At once an engine and a counting system, it is by far the most sophisticated assembly inside the watch. It determines timekeeping precision, and to a large degree the power reserve. Because this is where the greatest proportional energy losses take place within the movement, it also offers the greatest scope for optimization. The object of an infinite number of variations, inventions and theories, the escapement remains the most compelling subject of study for a designer and maker of watches.
The main escapement used today is the so-called Swiss lever escapement. It equips more than 99% of all mechanical watches produced, the reason being its unparalleled efficiency/simplicity ratio, which also makes it extremely economical. But there are other systems capable of very high precision and much greater sophistication. The natural escapement is one, and it has never ceased to titillate the imagination and desires of watchmaking designers.
First theorized by Breguet, it experienced a notable resurgence of interest in the course of 2010s. The escapement is said to be natural when the impulse is transmitted as directly as possible from the escapement wheel to the balance wheel. Breguet had imagined a system with two escape wheels operating alternately, but linked to each other by an additional pair of wheels, though these were quite energy-hungry.
During the 1980s, George Daniels, a British watchmaker based on the Isle of Man and recognized as one of the greatest watchmakers in recent history, continued Breguet’s work and devised his own version of the natural escapement. He implemented it in watches that are well-known to discerning collectors, the Space Traveller I and Space Traveller II, which broke records at auction.
Only the Daniels natural escapement, originally designed for a pocket watch, still offered possibilities for improvement in the sense of adapting it to contemporary needs, i.e. as a wristwatch. For instance, it operated at the very low frequency of 2 Hz and was not self-starting, making it necessary to shake the watch to get it going. Also, most of the existing Breguet-type natural escapements use a large number of components, which increases the weight and thus the energy required to power the timekeeper.
The Central Impulse Chronometer Escapement
To create a more precise and practicable natural escapement, Bernhard Lederer has decided to continue the effort started by Daniels and adapting it to a wristwatch, with all the challenges this would entail.
A frequency of 3 Hz was chosen because a watch worn on the wrist is subjected to countless shocks of varying intensity. Each one has repercussions on the movement’s regulating organs, i.e. the escapement wheels, but more importantly on the balance wheel with its spiral spring. With each impact, there is an acceleration or a slow-down, and the components find themselves twisted in their plane. They must therefore resume their intended course as quickly as possible, which is absolutely necessary for precision under everyday wear conditions.
In addition, the escapement is a system that spends most of its time at a standstill. Whilst the balance wheel is in perpetual rotation, it only activates the anchor at the end of each oscillation: when it has the highest velocity, i.e. the greatest force, and thus the best capacity to drive the mechanism. The anchor and anchor wheels are in a constant stop and go, accelerated and decelerated, which consumes energy and impairs isochronism and therefore precision.
To overcome these problems intrinsic to any escapement, the Central Impulse Chronometer uses components made from titanium instead of the more traditional steel. Lighter, stiffer and with a lower inertia, they are quick to restart and much more energy-efficient. In other words, the balance wheel’s rhythm remains virtually unaffected by the contact with the anchor.
It receives the force necessary for each impulse, itself an assurance of isochronism and therefore of timekeeping precision. The quantity of energy delivered is also controlled further upstream, in the gear train. Bernhard Lederer installed two independent gear trains, one for each escape wheel. Each of these kinetic chains has its own dedicated barrel. In addition, Bernhard Lederer inserted a constant force remontoire.
The constant force remontoire consists in accumulating an energy buffer in a spring similar to the one in the barrel, but one that is much shorter and lighter. Recharged in 10-second intervals, it capitalizes on the fact that the force of an unwinding spring is stronger when it is tightly wound up, and weaker when it is almost completely unwound. This variation in torque has a direct impact on isochronism.
The remontoire equalizes the force by ensuring a very homogeneous torque profile, with extremely minute variations in the energy delivered to the balance wheel. Here, Bernhard Lederer chose a design similar to the one invented in 1756 by John Harrison, where the remontoire recharging interval is managed by an anchor with a specific profile.
At a more fundamental level, the mechanical specificity of the Central Impulse Chronometer escapement lies in its anchor. It is the interface between the two escapement wheels, i.e. the gear train and the balance wheel. As the metronome, as it were, of the timepiece, it is where the energy of the former is transformed into the time information delivered by the latter.
To improve performance, the Central Impulse Chronometer’s anchor presents more points of contact between the components – whose shape, too, has been optimized. In particular, Bernhard Lederer has added a minutely small ruby, with a concave cut in the center, which advances the moment of contact between the escapement wheel tooth and the balance wheel impulse pallet.
Indeed, this is the most remarkable feature of the Central Impulse Chronometer: the manner in which it manages the moment and the contact surface of the impulse on the balance wheel. The impulse is direct and in alignment from the escapement wheel to the balance wheel, therefore theoretically perfect.
In addition, control of the impulse position is constant over time, both at low and high amplitude of the balance wheel. In fact, due to the geometry of the receiving pallet, the anchor will be able to give an indirect impulse to the balance wheel, allowing it to be always in the desired position when the direct impulse is given. As a result of the force being transmitted in this position, shocks are attenuated and the balance wheel receives the impulse in such a way as to ensure optimum isochronism and stability.
The concrete effect of this ingenious arrangement: fewer shocks between the components, smoother transfers of energy. The driving force is effectively dampened, though not in its intensity, but instead at the point of contact. It is when the escapement wheels and the balance wheel connect that the heartbeat of the watch, the ticking sound, is generated. These ever so slight impacts have been further mitigated to a degree that the Caliber 9012 is surprisingly quiet.
The Central Impulse Chronometer Watch
As a complement to his technical mastery, Bernhard Lederer has a particularity sensibility for design, having time and again distinguished himself in this regard. The Central Impulse Chronometer is no exception as it opens a new chapter in the watchmaker’s aesthetic language.
The sleek, 44-mm round pink gold case is elegantly understated. Its fine, smooth bezel emphasizes the vastness of the light grey, opalescent dial with a signature at 3 o’clock and raised beveled indices featuring a touch of SuperLumiNova™.
The shape of the rose gold beveled hands, a hybrid of leaf and baton, underscores the Bernhard Lederer aesthetic signature. Challenging the symmetry, a large-diameter, circular-finished small seconds subdial at 8 o’clock.
A sapphire crystal case back reveals the architecture of the Caliber 9012, which is symmetrical, angled, widely open-worked and quite large at 39.3 mm in diameter.
The Central Impulse Chronometer is also available in a white gold with an open-worked slate grey sunburst dial. The generous window provides an unobstructed view of the Caliber 9012 and its most distinctive features, namely the remontoires and escapement. It is the ‘technical’ counterpart to the ‘minimalist’ rose gold version, whose complexity remains hidden from view until the watch is turned over. On the white gold version, the skeletonized remontoire, gear train, escapement and balance wheel bridges featuring slender geometrical shapes are all visible from the front side.
Bernhard Lederer’s aesthetic signatures can be seen in every part of this large mechanical caliber whose two immense barrels, highlighted with fine gold, stand out throughout the movement. The wheel spokes are tangent curves with a unique profile, yet another Bernhard Lederer hallmark in a particular aesthetic universe that is not lacking in them.
Naturally, the level of finishing matches the engineering prowess at the core of the Central Impulse Chronometer. The polishing, inward and outward angles, microbead blasting, engraving, graining… The surfaces, too, alternate between matt and mirror polished, enhancing the visual separation between the different levels, and therefore the perception of depth and substance of the movement.
Model: Bernhard Lederer Central Impulse Chronometer
Hours, minutes, small seconds at 8 o’clock
Version 1: rose gold 5N 18K
Version 2: white gold 18K
Diameter: 44 mm
Thickness: 12.2 mm
Case back: Open, sapphire glass with double anti-reflective coating
Water resistance: 3 ATM, approx. 30 metres
Version 1: solid dial, silvered opaline
Version 2: open-worked, slate grey sunburst
Number of components: 208
Number of jewels: 44 rubies
Frequency: 21’600 vibrations per hour (3 Hz)
Diameter: 39.3 mm
Thickness: 5.98 mm
Power reserve: At least 38 hours
Two independent gear trains
Two constant-force remontoires
Natural escapement with central impulses
Winding & setting
Two-position winding stem:
Position 1: manual winding
Position 2: setting the time
Bridges diamond-beveled and drawn out
Brown satin alligator (rose gold version)
Black satin alligator (white gold version)
Pin buckle made of rose gold or white gold