Examining what Rolex wanted from its in-house developed chronograph, starting with the Cal. 4130 movement

Rolex is a manufacturer of practical watches that boasts high technical capabilities and is known for its solid designs. For a long time, Rolex used ébauche movements for its chronographs. The tide turned when they announced their own in-house developed chronograph movements in 2000. We will examine what they wanted from their in-house developed chronographs, starting with the movement.

Cal.4130 research

　Caliber 4130, Rolex's first in-house developed chronograph movement, was released in 2000. Automatic winding and a vertical clutch are now considered the standard for modern chronographs, but considering that many watchmakers began releasing chronographs with this specification one after another from the mid-2000s onwards, Rolex was undoubtedly a pioneer. However, as watch journalist Gisbert L. Brunner writes, "The development of this movement did not go smoothly at first. "At first, they considered using the Caliber 1185, an automatic chronograph from Frederic Piguet with three horizontal subdials, like the Daytona. Although this was later approved, at the time it was only possible to supply this movement to Blancpain."

　Since they could not use Frédéric Piguet's 1185, they had no choice but to develop it themselves. Marc Schmidt and Michel Santé were the core of the development team.

Bruner's assessment of them is that "They are a generation that did not experience the glory of the golden age of the chronograph, but they have succeeded in looking ahead to the 21st century." Perhaps it was precisely because they had no experience of the good old days of the chronograph that they were able to break free from the yoke of the horizontal clutch based on the Zenith El Primero that they had been using until then, and step into the new realm of vertical clutch.

　The biggest difference between the previous-generation Caliber 4030 used in the Daytona and the current-generation 4130 is the clutch. Although Seiko was unable to adopt the 1185, the vertical clutch of the 4130, which they developed themselves, was also different from that of the 1185. Please take a close look at the movement photo. Like the Caliber 6139 released by Seiko in 1969, a normal vertical clutch is based on a center-seconds train movement, with a friction wheel placed on the centrally located fourth wheel. However, with the 4130, the small seconds hand is located at 6 o'clock, so the vertical clutch cannot be placed in the center.

　Their solution was to incorporate a vertical clutch into the fourth wheel at 6 o'clock. By stacking the clutch on the offset fourth wheel, not only did they reduce the thickness of the movement, but they also enabled the small seconds hand to be positioned properly, without cross-eyes, despite the movement's large 30.5mm diameter. However, Rolex is known for its solid design, so this is hardly an afterthought. Placing the second wheel in the center, rather than the fourth wheel, would have made the minute hand less likely to jump when setting the time. Perhaps Rolex was trying to introduce a vertical clutch that would increase safety while also preventing the chronograph seconds hand from jumping. The LIGA gear was later adopted to further reduce jumping.

　When it was first released, this off-center vertical clutch was undoubtedly a challenge. Chopard's LUC10CF, released in 2006, also had an off-center vertical clutch, and like the 4130, it placed the vertical clutch near the column wheel, achieving stable control and operability. Six years before the LUC10CF, which is characterized by its robust construction, Rolex had already adopted a vertical clutch in a different way from the 1185, while also aiming for robustness.