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Caliber 12 to Valjoux 7740; How it Happened

In a previous thread, Nic raised the following questions about the relationship between Caliber 12 and the Valjoux 7740 movement:

    Anyway what i wanted to ask you was what was the relationship with the Chronomatic group and Valjoux? How did the 7740 and 7741 come about because these movements are identical to the calibre 11 but with-out the oscillating weight. Could the calibre 11 designs have come from this design or did Valjoux just use the design under license as long as they did not make it automatic? After all Valjoux where the biggest manufacturer of swiss chrono movements during the 60's so it would be natural for them to have had a part in the whole development.

Let me post this message, to pass along what I have learned.

During the production years of the Caliber 12 (and related movements), the companies had the following roles, in the assembly of the movements.

  • Buren supplied the base movements to Heuer (and Breitling);
  • Valjoux supplied the components for the chronograph module (Dubois-Depraz had designed this module, but did not manufacture these parts and components); and
  • Heuer and Breitling assembled the chronograph modules (from the parts supplied by Valjoux), and then combined the chronograph module with the base movement to produce the Caliber 12 movements.

Valjoux developed the 7740 movement from the Caliber 12 . . . in fact, except for one different component (relating to the way the module mounts to the base movement) and the oscillating mass / winding mechanism, the Caliber 12 and the 7740 are virtually identical. When Valjoux began making the 7740 movements, rather than using the Buren base movements, Valjoux itself produced the base movements. Remember, that at this time, Valjoux was one the the many companies that was a part of the Ebauches Group, so these base movements may have come from Valjoux itself or perhaps components for the base movement came from another supplier within the Ebauches Group.

I believe that Valjoux supplied these 7740 movements to Heuer and Breitling as completed movements, but I will need to check this information.

So, yes . . . the Valjoux 7740 came directly from the Caliber 12, and was almost identical in its main components.

I will attempt to confirm all this information, and can also seek further information in response to any questions.


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