When it comes to the Jaeger-LeCoultre brand, there is too much to talk about. I have the habit of collecting information and bought an internal material published in China 35 years ago. In this typeset book, details of hundreds of watch-related manufacturers in Switzerland that year were included, including Jaeger-LeCoultre. At that time, Jaeger-LeCoultre was also transliterated as ‘Jacques-Le Coulter’ Co., Ltd. instead of the current ‘Jacques’. And its business scope also specifically stated as the production of ‘quality watches and clocks, air pressure clocks (air clocks)’. As the name suggests, Jaeger-LeCoultre is actually a merger of two companies. One is Jaeger and the other is LeCoultre. In 1833, Switzerland’s Antoine LeCoultre invented a clock gear production machine, and then he opened his own small workshop to set up production of movement parts. With the joint efforts of Antoine LeCoultre and his son, the scale of the workshop has become larger and larger. By 1903, Edmond Jaeger of France found the LeCoultre workshop, hoping that LeCoultre could provide him with a movement. Edmond Jaeger later took the movement of the LeCoultre workshop to produce watches for the famous French brand Cartier. To put it simply, it is sub-contracting layer by layer … With the deepening of cooperation, LeCoultre and Jaeger formally merged into one company. The merged Jaeger-LeCoultre continues the watchmaking tradition and specializes in high-end movements. Its products have been used by many companies that are positioned on top of today’s brands, including but not limited to: Patek Philippe, Vacheron Constantin, Audemars Piguet, Lange. …. Today, what I am sharing is an interesting model from Jaeger-LeCoultre-Duomètre à Chronographe two-wing single-button chronograph watch. At first glance, the design of the Duomètre à Chronographe dial is very symmetrical and regular. The left part shows the normal time. The right part shows the two long second hands in the center of the chronograph. At first glance, I thought it was a double chase. It is actually a large second hand and a chronograph second hand. When the chronograph function is reset to zero, the blue chronograph second hand is aligned at the 12 o’clock scale. And at 6 o’clock there is a small dial, here is to display ‘sixth’ seconds. Although there are many positive pointers, we can distinguish them by color. Gold belongs to the hour, blue belongs to the time. At the same time, there is a power reserve display in the lower left and right corners, respectively corresponding to the power reserve time of the two gear trains, each of which is 50 hours. Almost all of our common watches use a ‘single gear train’. The energy is released from the barrel and transmitted to the escapement balance via gears. If you just let the hour, minute and second hands run, this design is enough. However, if we need to add other functions, such as timekeeping and calendar, it will affect the swing of the balance of the watch, which will cause interference in the accuracy of the travel time. At the same time, these additional functions will also consume some energy, reducing the normal power reserve time of the watch. In order to solve this problem, Jaeger-LeCoultre proposed the Dual-Wing design concept. The dual-wing system is divided into ‘two sets of gear trains’: one set shows normal travel time, and the other shows secondary functions. The two sets of mechanical devices share the same escapement balance system, and each has its own independent power source. However, the design concept of ‘two sets of gear trains’ was not first proposed by Jaeger-LeCoultre. What Jaeger-LeCoultre proposed could only be called ‘Dual-Wing’. To put it simply, Jaeger-LeCoultre just took a name ….. and the most common design concept of ‘two sets of gear trains’ is on the minute repeater clock. Minute movements are usually equipped with two barrels, one large and one small. The large one is responsible for the normal travel time, and the small one is responsible for supplying energy to the hammer to hit the gong to make a sound. The two barrels drive different gear trains without disturbing each other. Therefore, for the three questions, even if the balance wheel is stopped, you can start the timekeeping function to make a sound alone. So why don’t other brands make such a ‘two sets of gear trains’? That’s because such a design is too complicated, taking up a lot of space, and the size of the movement cannot be made small. Therefore, this Duomètre à Chronographe has as many as 455 movement parts and a thickness of 6.95 mm. Through the sapphire back, you can clearly see the two side-by-side barrels in the movement. The left one is responsible for the chronograph function, and the right one is responsible for the normal running time. No matter which direction you turn the crown when you wind up, one of the barrels can add energy separately. The check box of the mainspring adopts the internal check mode commonly used in the pocket watch era, which is more expensive and more beautiful. The ‘two sets of wheel trains’ share one escapement balance wheel system. In order to realize the function of one-sixth of a second, a gear is superimposed on the escape wheel for transmitting a fine time interval. The timing function is controlled by a single button, which can be started, paused, and reset to zero with one thumb. It also uses the classic column wheel structure. Initially, Duomètre à Chronographe is a watch with a brand, a dial and a movement. It is interesting and fun. However, in the actual test, an awkward problem was found. Jaeger-LeCoultre proposed the Dual-Wing design concept. The dual-wing system is divided into ‘two sets of gear trains’: one set shows normal travel time, and the other shows secondary functions. The two sets of mechanical devices share the same escapement balance system, and each has its own independent power source. However, after starting the timing function, interference will still occur due to the interaction between different functions. At first, I thought it was because of a problem with this watch. Jaeger-LeCoultre spent so much effort to make this watch, but it still had an impact. So I found another piece of the same model and performed a second test, and found that it was still the same. At the same time, we found another FP Journe watch with the same concept design, two sets of wheels, and a single escapement balance. The final test results are still the same as those of Jaeger-LeCoultre. Therefore, the design of ‘two sets of gear trains and a single escapement balance wheel’ is just like a ‘tourbillon’. It is theoretically great, but in practice it cannot completely solve the problem. Of course, this article is not written so that everyone should not buy this Jaeger-LeCoultre biplane chronograph, but rather want to share the true story behind it. Just like the tourbillon, although it is not as accurate as the basic basic movement in common use, the research and development story behind it, the precise mechanical structure, and the innovative spirit of exploration have attracted many table friends. —END —