Technical notes: Urwerk AMC

Urwerk announced an interesting extension to their concept EMC watch this SIHH. The spirit of the new movement, called AMC, is a master-slave clock wristwatch in the fashion of the Breguet Symphatique. On the Breguet, the clock sets and winds the pocket watch. In the Urwerk AMC, the atomic clock, via a complex mechanical linkage, winds, sets and regulates the Urwerk AMC. In SIHH 2018, Urwerk did not show the watch nor the carrying this technology, but a prototype watch movement, with the expressed promise that they will do so for the upcoming Baselworld. In this article, we examine the technical aspects of this invention, with live photographs of the prototype movement. 

Both the atomic master clock and the watch is specicially designed for the AMC project, and together, they represent the first time a mechanical watch and an atomic clock is so linked.

 

 

Historical underpinnings

 

“I have great pleasure, my friend, in telling you that I have made a very important invention, but about which you must be very discreet, even about the idea. I have invented a means of setting a watch to time, and regulating it, without anyone having to do it … then every night on going to bed, you put the watch into the clock. In the morning, or one hour later, it will be exactly to time with the clock. It is not even necessary to open the watch. I expect from this, the greatest promotion of our fame and fortune.”

Abraham-Louis Breguet,

in a letter to his son in 1795

So that is the basis of the new Urwerk AMC. A watch with a symbiotic relationship with a clock. In Breguet’s case, the system known as Symphatique is a pocket watch which is set to time and regulated by a table clock when it is placed in a recess in the latter. Three types of Sympathiques were manufactured over the twenty-five years following 1795.  Breguet himself does not describe any Symphatique watches that are set to time and wound by the clock, only those set to time and regulated. The earliest known Sympathique to feature rewinding was made in 1812 by Louis Rabi, one of Breguet’s most most capable pupils. Claude Breguet (reference Antiquorum auction Geneva 14th April 1991) recorded only seven Symphatique watches with clocks in his monograph. However, the majority of the clocks are dated after Breguet’s death in 1823. It is unlikely that A.L. Breguet himself built these systems, but certainly the concept and idea of such a device originated from him.

Approximately 12 Sympathiques are known at this time. Of the existing Sympathique clocks, three were made for the Spanish Crown; four were made for the Russian Crown; one was commissioned by Napoleon as a state gift for the Turkish Sultan, Mahmut II; and one was made for the British King George IV at the time of his Regency. Of the entire group, eight are retained by national museums. Only four have been offered at public auction, one of which is now in the Beyer Clock and Watch Museum in Zurich. The others were purchased by private collectors. Of the known clocks, few have remained in their original state and some no longer possess their original watches. (reference Sotheby’s auction NY 4 Dec 2012)

 

 

The example sold by Antiquorum was owned by Francis Baring. It acheived a hammer price of  CHF 1,216,250 on 14 April 1991. Sotheby’s example was owned by Duc d’Orléans and was sold on 04 December 2012 for US$ 6,802,500  (Hammer Price with Buyer’s Premium)

The Breguet Symphatique was a very complicated of machinery, and the known examples soon fell into disrepair. The Duc d’Orléans example was found in a poor state of disrepair. And was first restored by none other than the celebrated horologist, the late Dr. George Daniels.

 

“I had located the piece in Paris through a French Antique dealer in 1974. The whole self-winding mechanism was missing, probably because, as so often happens with complex mechanisms, a repairer couldn’t reassemble it properly. But only a half dozen or so Sympathiques were ever made, so Atwood was pleased to be able to purchase it. My task was to replace the whole of the mechanism while filling all vacant holes and without making any new ones. At that time, I was filled with a passionate love for Breguet’s work and was at the peak of my understanding of his philosophy. The work presented no difficulty and was tremendously enjoyable.”

George Daniels

in his biography All in Good Time (2006)

 

Relevance to Urwerk

Since the Urwerk EMC (see link here), the team at Urwerk has been pushing the limits of combining electronics with the mechanical heart of watchmaking. In the EMC, the design featured a rate measuring system built into the watch which allowed the owner to measure the beat rate of his EMC. In the new AMC, the Urwerk watch will feature a system of a master clock and a wristwatch. The master clock is an atomic clock  which is conceived and developed in Urwerk’s workshops. This master clock will rewind the Urwerk wristwatch, set it to the correct time and if necessary adjust the rate. All the three features which defined the Breguet Symphatique.

The wristwatch will be a rather typical Urwerk, and will feature a power reserve indicator, two stacked barrels for a four day power reserve. It will also have the Oil Change Indicator, which records the cumulative running time of the movement and recommends service when necessary. One full rotation of the indicator measures four years of cumulative running time.

 

The Urwerk AMC

At SIHH, Urwerk did not show the clock, as it is still under development. The watch itself is also under design development, but the concept was demonstrated and we were shown the AMC movement.

 

 

The watch and master clock interacts in three ways:

ONE: the clock is able to adjust the beat rate of the watch. To do this, the master clock needs a mechanism to read the time, compare it to the atomic time and adjust the rate to be faster or slower accordingly. In Breguet’s Symphatique, this mechanism resides in the watch, triggered by an actuating rod extending from the clock to the watch when the clock reads a specific time. In the AMC, a similar system is used, but the reading mechanism resides in the master clock. At the time of adjustment, a pusher extends from the clock to the watch, and pushes on the foot of a lever with a pair of calipers pivoting on a common axis opposite to the lever. This is shown in the drawing below. The caliper is thus able to feel if the time on the watch, as indicated by the position of the half moon cam, and compare it with the internal timing of the master clock.

 

 

 

If the time of the master clock and the watch are exactly synchronized, to the second, situation 1 occurs, both jaws fall equidistant from each other. If they are not exactly synchronized, then one of the jaws of the caliper will fall further than the other. This will cause the cam to rotate, and due to the shape of the cam, one of the two caliper jaws will also move. Which jaw moves tells the mechanism whether the watch is beating faster or slower than the reference.

Each jaw has a tooth on its central pivot which engages a toothed wheel in a spiral cutout, moving it either clockwise or anticlockwise. This is used to adjust either to speed up or slow down the rate of the watch. The granularity the system is capable of retaining is to adjust plus or minus 2 seconds a day.

The shape of the cam is critical in being able to accurately read the rate discrepancy.

TWO: Distinct from rate adjustment, the exact synchronization of the minutes and seconds display of the watch and the atomic master is performed.

This mechanism used to set the minutes and seconds is activated by a pusher triggered by the master clock at a certain time. The pusher moves a lever system which will move to engage with a heart shaped cam. When activated, this resets both the seconds and minute hands to zero, to synchronize with the clock. Much like a chronograph resets to a zero position.

THREE: A shaft extending from the clock acts on the crown to wind the watch when the latter is placed in its cradle.

 

 

Further thoughts

The AMC system is rather interesting. Some 220 years after the Breguet Symphatique, we now have a system with the same features, but updated with the latest modern technology.

The mechanical wristwatch is the traditional combination of springs and levers and wheels. Continually refined over the years, but no doubt still a system which Abraham-Louis himself would be able to comprehend. The atomic clock, on the other hand is the cutting edge of modern timekeeping. This is a clock which uses the frequency of a known gas to determine its own rate, and is so stable that it is accurate to better than 1 second over a million years. This clock is essential in the workings of modern society, and is carried on board every GPS satellite which uses its unwavering accuracy to calculate the position of any object on earth.

This juxtapositon, and its apparent dichotomy does not escape us. But rather triggers a bewilderment. We wait with great anticipation what Urwerk will reveal when the project comes to fruition. Hopefully in a couple of weeks in Baselworkd 2018.