The Valjoux 72 — a chronograph worth understanding
The Valjoux 72 powered some of the finest chronographs of the 1960s and 1970s.
It is a column-wheel movement, which gives it a mechanical refinement that the later cam-operated calibres lack.
Watchmaker Bernhard Zwinz started with a blank sheet when dreaming up what became the calibre CW03. It powers his latest reference, evocatively named Heart Return, and Zwinz worked on the movement for six years, layering historical inspiration with mechanical novelty.
The end result is a movement that centres two functions. The first of these is the zero-second reset or Heart Return function that gives the watch its name. The second is the jumping power reserve indicator. While both are unusual, one is wholly novel to modern watchmaking. Crucially, both are interpretations of advances championed by 19th century Austrian master Joseph Thaddäus Winnerl whose name and philosophy his compatriot Zwinz aims to perpetuate.
Jumping power reserve indicator When Zwinz was hoping to add a power reserve complication to Winnerl vernacular, he again sought inspiration in the marine chronometre No. 80. That watch contained a solution to a problem that is true of almost all power reserve set ups. The complication typically requires constant surveillance of the reserve in the mainspring barrel, with a cam-mounted indicator hand on the dial exerting a constant irregular drag on the barrel while doing so. Such friction is of course ill-suited to the mainspring’s purpose of delivering steady torque.
Zwinz’s solution, like in the No. 80, is to take just seven reads over the course of the 49 hours of chronometric reserve in the mainspring barrel. The rest of the time, the mainspring barrel is under no strain from the marine chronometre-style power reserve display.
Zwinz says, “Most power reserve indicators today show what remains in the mainspring. In J. Th. Winnerl's marine chronometers, from the 1830s onwards, however, the indication reflected the energy that had already been used. This approach aligns closely with J. Th. Winnerl's spirit: measuring and understanding the passage of time rather than predicting what remains.”
