La Tradition Quantième Rétrograde

There was a famous American comedian, Rodney Dangerfield, whose decades’ long career was built upon the phrase “I don’t get no respect, no respect at all”. In some ways, the date complication falls into that category. For almost all timepieces, adding a small window displaying the date printed upon a ring supported on the dial side of the movement or adding a classic date hand, is simple to implement and falls into the category, which many watchmakers would describe as a “petite complication”. Useful, certainly, but not something that is seen as a difficult watchmaking triumph. No respect, indeed.

However, not all date complications can be seen in that light. Most certainly not one bringing a date indication to the Breguet LaTradition family where the standard implementation of a rotating ring or standard date hand simply would not do. With the usual construction rejected out of hand, Breguet’s watchmakers confronted two daunting challenges: finding another way to integrate a date display that would harmonize with the layout and aesthetics of the Tradition collection and, second, how to incorporate the mechanism into the limited space available under the off-center dial.

The construction of today’s La Tradition recalls the pocket watch created by founder Abraham-Louis Breguet, numbered 960 and delivered on October 2, 1806 to the famed hydraulic engineer, Augustin de Bétancourt. The links to this historic timepiece are easy to spot: the winding barrel centered on the mainplate, time displayed on a small off centered guilloché dial, the gear train running from the balance wheel and escapement gracefully arcing below the barrel, the shapes of the bridges, the parachute anti-shock system.

Adding the date needed to be done in a way that would be both easily readable without disturbing the harmony of this timeless layout. Many months were devoted to considering alternatives before the movement designers settled upon positioning a band numbered for 31 days along the lower edge of the movement, with the date indicated by a hand reading upon the band. As the hand would advance daily throughout the month, upon reaching “31”, it would swiftly return to “1”, or in the parlance of watchmakers, “retrograde”.

Breguet confronted two challenges in designing the date complication for the Tradition: first, how to harmonize the indication with the Tradition’s open aesthetic and, second, how to incorporate the mechanism into the limited space under the dial.

pocket watch No. 960

pocket watch No. 960

Breguet’s Tradition Collection has been inspired by pocket watch No. 960 delivered on the 2nd of October 1802 to famed hydraulic engineer Augustin de Bétancourt. With examination of this historical piece, the links to today’s timepieces burst forth – a central winding barrel, the dial located at the 12 o’clock position with hands driven directly from the barrel, the graceful curve of components with the balance wheel and intermediate wheels arcing across from the 4 o’clock to 8 o’clock positions, the parachute anti-shock system, the shape of the principal bridges. This shared fundamental architecture of the two movements joins together watches created two centuries apart.

The basic concept of how to display the date was but a beginning point. What remained was developing a mechanism that could be integrated into the movement. A retrograde date system, by its very nature, is a complicated construction. Ordinarily, an implementation this complex would be built upon a separate plate, placed above the mainplate of the movement.

That approach would be completely incompatible with the design of La Tradition for it would remove from view the core elements of the movement, whose display is core to the line’s DNA. The challenge confronting the designers, thus, became how to integrate a complex retrograde system into the movement while at the same time not disturbing the view of the other movement components. This imperative meant that the entire mechanism would have to be placed under the 18.5 mm off-centered small guilloché dial.

Consider for a moment the particulars of a retrograde date system when compared to a standard rotating disk under the dial or a date hand that rotates over 360 degrees. Both a rotating disk and a conventional rotating hand require only a 24 hour wheel and a means to engage a 31 tooth element to advance the indication daily at midnight. By contrast, a retrograde date must translate the rotation of 31 tooth wheel that turns 360 degrees, into movement over a smaller arc. In addition, a method needs to be added to store energy so that the hand can be smartly returned from the end of its travel back to the beginning position of “1”. Finally, the design must include protection of the mechanism if the time is adjusted backwards past midnight.

A retrograde date system by its very nature is complex, particularly so when not implemented on a separate plate.

As with essentially all date complications, the Tradition date system is driven by a 24 hour wheel (B). In this case, that wheel is powered by a wheel (A) engaged directly to the mainspring barrel. Solidly attached to the 24 hour wheel is a flexible spiral (C) which terminates with a finger. At midnight, the finger rotating with the 24 hour wheel, engages an intermediate wheel (D), turning it one tooth. The design of the flexible spiral with its finger is quite studied. If the time is adjusted backwards through midnight, its shape and flexibility allow the finger to slide past the rest of the date system without disturbance or damage. Additionally, its shape has been engineered to ensure proper functionality in all positions, even those where gravity would potentially pull the finger away from the tooth. In turn, the intermediate wheel is engaged with a 31 tooth wheel (E). The advancement of the intermediate wheel, by one tooth, advances the 31 tooth wheel, likewise, by one tooth, which would correspond to one day. In order to maintain its position, there is a small spring (N) with a finger holding the wheel (M) in place after each advance.

However, the one tooth advance of the 31 tooth wheel is far from the end of the matter. Recall that this system is far more complex than a simple date hand directly attached to a wheel. When the center of the date system is a 31 tooth wheel that turns 360 degrees over that period and the date indication, likewise, is shown over a full 360 circle, the correspondence between the rotation of the wheel and the indication is direct. No translation needed.

However, with a retrograde system, where the 31 days are not arrayed over 360 degrees, but rather an arc of 153 degrees, a full circle of rotation had to be translated into the smaller arc. In order to accomplish the translation, Breguet has fitted the 31 tooth wheel with a solidly attached snail cam (F), which has 31 rounded steps and a sharp drop off at the end. Engaged with the snail cam is a rake gear (G) with an adjustable finger positioned by an eccentric screw (H), that, in turn, is connected to a gear (I) attached to the date hand (J). With each advance of the 31 tooth wheel, its solidly attached snail cam turns. The finger in contact with the snail cam, in turn, is slightly displaced, which, through the rake, advances the date hand.

The connection between the snail cam and the finger that rides along it, is critical to the system. In order that each movement of the 31 tooth wheel and its cam will produce a precisely centered advance in the date, Breguet has fitted the finger tip with an adjustable eccentric screw (H). When the watch is assembled, the watchmaker can make fine adjustments in the engagement of the cam and the finger to ensure that the daily advance will be correct. This adjusting system has been patented by Breguet.

Unlike common date indications which are based on 360 degrees of rotation, the retrograde date for the Tradition is based upon an arc of 153 degrees. Thus, a retrograde system was designed.

Forward from 1 to 31

A    Wheel engaged directly to the mainspring barrel
B     24-hour wheel
C    Flexible spiral with a finger (attached to the 24-hour wheel)
D    Intermediate wheel
E    31-tooth wheel
F    Snail cam (solidly attached to the 31-tooth wheel)
G    Rake gear with an adjustable finger
H    Eccentric screw (adjustable, positioned by the rake gear)
I    Gear attached to the date hand
J    Date hand

Thus far, we have described the elements that advance the date forward from 1 to 31. Additional components come into play to enable the retrograde back from 31 to 1. Connected to the date hand gear is a second rake (K). With each forward movement of the date, the rake turns slightly. On the back side of the mainplate, the daily turning of this second rake arms a very fine blade spring (L).

Several things happen after day “31”. First, the finger (G) that has been riding along the edge of the snail cam (F) attached to the 31 tooth wheel, encounters the drop off portion of the cam. The drop off frees the finger to move in the opposite direction from its advance, powered by the blade spring (L) that has accumulated tension over the 31 days.

Of course, the opposite direction move of the finger turns the date hand backwards which is the retrograde from “31” to “1”. The spring also serves additional second purposes as it keeps the rake in contact with the snail cam and prevents play in the date hand that might result from movement within the trough of the teeth.

The date hand itself was the subject of clever design. In order to allow pivoting from the center of the watch, the arbor of the barrel was specially designed to accommodate the hand’s axis. Further, since its pivot point was located beneath the dial, its shape was designed with a small upward step to bring it to the level of date arc.

Back from 31 to 1

K    Second rake (connected to the date hand gear)
L    Blade spring (armed by the second rake)
M    Small spring N with finger M that holds the 31-tooth wheel in place between daily changes.
O    Manual rapid correction

Tradition Quantième Rétrograde 7597

Tradition en or blanc 18 carats avec quantième rétrograde. Mouvement à remontage automatique. Spiral Breguet en silicium. Cadran excentré en or argenté guilloché à la main. Étanche à 3 bar (30 m). Diamètre : 40 mm.

Découvrir

There is one further complication to this construction: the date hand itself. The most harmonious arrangement for the poising of the hand would have it pivot from the center of the watch. The concept appears straightforward; the implementation requiring creativity.

The design of La Tradition places the barrel in the center of the movement, which means that its central arbor is located precisely in the desired location for the date hand axis. The answer was to hollow out the barrel arbor so that the shaft of the date hand could fit within it.

The top end of the date hand axis is fitted within a ruby pivot in the bridge hidden beneath the dial. Because the date hand must pass above both bridges and the balance wheel of the movement, its profile is raised on the portion removed from the center. Achieving this profile invoked a complex shaping process to ensure accuracy and stability.

There remains one other key design element required to complete the date system: manual rapid correction (O). Here, Breguet fitted the timepiece with a pusher at 10 o’clock, protected against inadvertent activation, by a screw down guard.

In other respects, the new Tradition hews closely to the Tradition Automatique sharing the architecture of its major components and form of the winding rotor inspired by the oscillating weight of historical perpétuelle watches, perhaps the most famous example being pocket watch No. 160, the Marie Antoinette. Also in common is the case diameter of 40 mm. Power reserve remains the same, 50 hours.

There is a difference in the sapphire crystal as this new version features a glass box, a slight elevation in the sides of the crystal to bring more light into the movement enhancing the view. Three versions are offered, one in rose gold, the other in white gold, both with a rhodium plated solid gold guilloché dial; the third version introduces the color blue to the Tradition lineup as the gold guilloché dial has been given a blue coating with the same color carried out for the date band.