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Breguet - Tradition independent chronograph

Breguet Tradition independent chronograph

A detailed look at a rare complication.

The atmosphere is indeed thin at the pinnacle of fine watchmaking. To secure a place there a watch house must have mastered, on its own—or as it is expressed most often, “in-house”—the full range of haute horlogerie’s greatest challenges: perpetual calendars, tourbillons, repeaters, and, of course, chronographs. In Breguet’s case not only are all these found within its collections, but multiple versions of each so that there is stunning diversity in the different movements which Breguet offers for each of these complications including chronographs1. Not only is the range of Breguet’s chronographs broad, but nestled within it is the caliber 2320, as it is known internally, or 533.3, as it is known publicly, which for decades has reigned as the most honored haut de gamme chronograph movement in the world (See Issue No. 2 for the history of this caliber and its unprecedented adoption by a wide swath of Switzerland’s prestige watch houses).

Logically, Breguet could have rested upon these past achievements and left untouched its collection of chronographs. Instead, the halls of Baselworld 2015 were set abuzz as Breguet debuted its sixth chronograph caliber with the Tradition Independent Chronograph. This new chronograph represents far more than an enrichening and broadening of Breguet’s chronograph choices, for it presents a construction which has never been seen before and opens a new chapter in the history of chronograph evolution.

A brief tutorial in chronograph basics places this new movement in context. Essentially all of the world’s chronographs incorporate some form of switching mechanism. When the chronograph is started by the owner, universally by pushing a button, the switching mechanism is used to connect the chronograph components to the regular running train of the watch. The reverse is true when the chronograph is stopped at the end of a timing event; the push for “stop” causes the chronograph components to be disconnected from the running train. Over the past two centuries of chronograph development, watchmakers have developed and perfected a multitude of different switching systems for accomplishing this connection and disconnection. Take for example, the 2320/533.3. It employs a highly evolved column wheel/horizontal clutch system that connects the chronograph to the running movement by pivoting together two finely toothed wheels.

The Tradition Independent Chronograph has no such switching mechanism for connection or disconnection. Indeed, the starting and stopping of the chronograph takes place without any connection/disconnection from the main movement of the watch. Those two sentences, alone, emphatically make the point about just how revolutionary and new this movement is. The undertaking of its creation was the very definition of a white sheet of paper project with no carry over from predecessor chronographs.

Tradition independent chronograph

Breguet Tradition independent chronograph © Breguet

 

So if there is no switching mechanism to connect the chronograph to the running train, how can it function? The answer is found in the name, more particularly in the word “independent”. The chronograph has its own movement separate and independent from the principal movement of the watch. For connoisseurs, the presence of two separate timekeeping elements is seen at once as the Tradition Chronograph is equipped with two balance wheels (one dedicated to the chronograph, the second dedicated to the main movement), symmetrically arrayed adjacent to each other and both visible from the front of the watch. In common with all the non-tourbillon models in the Tradition collection, both balance wheels are fitted with parachute anti-shock systems. Both balance wheels share the same diameter, which bestows a visual coherence to the timepiece.

As novel as it may be to place an independent chronograph with an identically sized balance alongside the main watch, banish all thoughts that the separate chronograph movement has been built in accordance with movement convention, as Breguet has conceived it in an entirely pioneering way. As testament to the inventiveness of this new design, Breguet invested five full years in its development and has filed several patents covering its construction. 

Of course, the heart of the chronograph movement is a free sprung balance wheel with a Swiss lever escapement. The balance’s spiral incorporates an important historical Breguet invention, an overcoil. The overcoil, which consists of a curve at the terminal end of the spiral positioned above the spiral's main body, helps ensure that the spiral will expand and contract more uniformly for better timing performance. Today, the entire industry honors this historical Breguet invention, terming this type of terminal curve a “Breguet overcoil ”. So far, that represents a standard way to approach a movement design, albeit with a healthy dose of Breguet’s modern research that has led to the development of a balance wheel fashioned in titanium and its Breguet overcoil spiral in silicium, running at, what is for a chronograph, the ideal frequency of 5 Hz, which neatly divides each second into tenths. The remainder of the chronograph’s construction opens up entirely new frontiers. 

So hewn to standard practice that watchmakers consider it universal—and it has been thus since the 1500s— the component that supplies the energy for mechanical timekeeping mechanisms to run is a barrel fitted with a spiral-formed mainspring. Not surprisingly, the main watch half of the Tradition Independent Chronograph is equipped with just such a barrel/mainspring. The chronograph half, however, has neither a barrel nor a spiral-shaped mainspring. Nor is it equipped with a crown to be wound to store energy. How then is the chronograph powered? With a straight “blade” spring. When the chronograph reset button is pushed for the return to zero, that action alone loads the spring blade with enough energy to power the chronograph. One of the key benefits wrapped up in this arrangement is instant charging of energy for the chronograph with a single button push. There is never a question of whether a barrel is sufficiently wound; the chronograph is always ready to run the moment that the start button is pushed.

Tradition independent chronograph

There are two balance wheels; here the titanium balance for the chronograph is ready for assembly © Breguet

Breguet did not leave matters there, however. Any spring system delivering energy to a balance wheel/escapement has a disability. The amount of force varies over the course of time that the spring is transmitting its energy. There is more force when it is fully charged than when it is nearly fully discharged. This is as true of a traditional barrel with a spiral mainspring as it is for a blade spring. To compensate for this characteristic of the spring, Breguet equipped the Independent Chronograph with an innovatively constructed constant force system which is integrated into the mechanism that delivers the energy to the chronograph balance wheel. This novel system is the subject of one patent.

The chronograph is equipped with two buttons, although their placement and functions depart from the usual. The button at the 4 o’clock position is used for the start. Stop, however, instead of being associated with the same button (as is the case with most chronographs), is assigned to a button at 8’clock. A restart can be commanded by another push of the 4 o’clock button. After a stop, a second push of the 8 o’clock button returns the chronograph to zero (and remember that it is this push for “reset” that arms the blade spring). Along with new assignments for the buttons, come creative mechanisms associated with each command. At the center of these new mechanisms is an inspiration from Breguet’s history, fitting, of course, as this timepiece is, after all, a member of the Tradition collection. Recalling Breguet No. 4009 sold in 1825 to Mr. Whaley (a double seconds stop function pocket watch), the Independent Chronograph is equipped with an anchor shaped chronograph control of similar form. When the start button is pushed, the anchor pivots in order to lift the hammer component that holds the position of the chronograph seconds hand and, simultaneously, frees the chronograph balance wheel. Recall that the blade spring was already armed from a previous push for the return to zero. However, the balance is not allowed to run when the chronograph is stopped as an arm is pressed against its axis, blocking it from swinging. Once that pressure from the arm is released, the balance is able immediately to start. A common behavior with mechanical watches is a delay in the starting of a balance wheel if the watch has been allowed to run down. To ensure that this does not occur with the chronograph balance, Breguet has designed the stop so that there will be tension on the spiral of the balance wheel. Thus, when the stopping arm is lifted an instantaneous start is assured every single time.

A second function of the anchor comes into play when the chronograph is stopped. The anchor is used to accomplish the return to zero of the chronograph seconds hand. A finger attached to the anchor causes a hammer to rotate bringing the hammer in contact with a classic heart-shaped cam attached to the shaft of the chronograph indicators. Chronograph aficionados know that heart-shaped cams universally are used to return hands to the zero position. Owing to their precisely calculated logarithmic shape, when a hammer is pressed anywhere along an exterior edge, that pressure always causes the cam to rotate smartly to a predefined single position, which, of course, is the zero position.

Tradition independent chronograph

The switching element for the chronograph © Breguet

 

The chronograph seconds hand reads upon a scale on the exterior dial. Since the chronograph half of the movement oscillates at 5 Hz, each second is perfectly divided into 0.1 second increments and can easily be read on the exterior dial. Echoing the symmetry of the two balance wheels of the same size poised opposite each other, the minute counter scale of one to twenty minutes is set out on an arc that mirrors that of the arc placed opposite it used for the power reserve indication of the main watch.

Generally speaking, throughout the watch industry little is said or published on the subject of chronograph precision. For most chronographs, the connection of the chronograph mechanism to the running train of the watch adds an additional load that affects the running rate of both the main time display and the chronograph itself. This does not, however, apply to the Independent Chronograph since the main watch and chronograph run separately from each other. Thus, Breguet is able to announce the precision for the chronograph. The number is astonishing: +/- .08 seconds over twenty minutes! To put that into perspective, since the chronograph divides each second into tenths of a second, a miniscule possible error of less than .08 seconds is hardly, if at all, readable.

To this point we have focused entirely upon the innovations in the chronograph portion of the watch. A few points concerning the main watch: as mentioned earlier, the main watch’s balance wheel is identical in size to that of the chronograph. It is fashioned, though, out of a heavier material, Glucydur, so that it will run at a frequency of 3 Hz. Like the chronograph, it is equipped with a Breguet balance spring in silicium. 

The hours and minutes are read upon a solid gold hand guilloche dial, which like other models in the Tradition collection, is placed off center. Manually wound, the main watch achieves a power reserve of 55 hours.

The Independent Chronograph is available in either red gold or white gold, both versions with a case diameter of 44 mm.

 

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Breguet’s archives, kept in Switzerland and in Paris, record the developments that have sustained Breguet watchmaking for more than two centuries. The firm is committed to remaining ahead of its time with a flow of inventions and improvements.

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