|Diameter:||31.00 mm (14 ligne)|
|Complications:||2-Button, Cam Switching Chronograph, Chronograph, Date, Hand Winding, Oscillating Pinion Chronograph, Quick Date Correction|
|Hands:||12 Hour Chronograph Hand at 9:00, 30 Minute Chronograph Hand at 3:00, Central 60 Second Chronograph Hand, Central Hour Hand, Central Minute Hand, Date Window at 6:00|
|Distinguishing Technical Characteristics|
Clockwise Balance Cock
|Production: 1972 –|
Cal. 7740 is a cam-operated chronograph movement with 30 minute and 12 hour counters and date. The similar Cal. 7741 adds a central 24 hour (GMT) hand.
Cal. 7740 uses an oscillating pinion for smooth and reliable chronograph engagement rather than the traditional horizontal clutch. The top pusher starts and stops the chronograph, while the bottom one resets the chronograph to zero. It has a semi-instantaneous date mechanism showing the date in a window at 6:00 on the dial.
Although derived from the Vénus 188 family, Cal. 7740 was much refined. After the merger of Vénus with Valjoux, the Vénus Cal. 210 became the Valjoux 7730, and this was modified to become the Valjoux 7733. Cal. 7740 replaces most of the components of this movement. It is a simple design, with a single bridge for the barrel and wheel train and the middle wheel is moved off-center and set on jeweled bearings. The equidistant escapement has a 20-tooth wheel and fixed banking, allowing operation at 28,800 A/h. The balance cock has a shock absorber, adjustable stud holder, and simple non-indexed regulator. Despite only being sold as a chronograph, it is a modular design so the chronograph mechanism can be removed as a single unit for service or replacement.
A 1972 article in Europa Star describes the movement as “new”, suggesting that it was introduced that year. It likely remained in production for only a few years, since Valjoux’s automatic 7750 movement was introduced the following year and entered production in 1974. Still, Cal. 7740 was produced in great volume by Valjoux in Les Bioux and Moutier.Images are taken from official publications and are used here for commentary and educational purposes. Copyright is held by the original owner as noted.