constant force – WatchesAndMoreCO

📅 Saturday, August 8, 2026

To combat the decreasing torque of an unwinding mainspring, master watchmakers developed the remontoire d’égalité. This ingenious auxiliary spring delivers a perfectly constant pulse of power to the escapement, and it automatically rewinds itself from the mainspring every few seconds in a mesmerizing mechanical dance.

Mechanical watches face a fundamental problem: a mainspring doesn’t deliver exactly the same amount of torque throughout its entire power reserve. As it gradually unwinds, the changing force reaching the escapement can affect the amplitude of the balance—and potentially the watch’s rate. The remontoire d’égalité, or constant-force remontoire, is one ingenious solution.

Instead of allowing the mainspring to power the escapement directly, a remontoire places a small secondary spring or other energy-storage device within the gear train. The mainspring periodically rewinds this intermediate mechanism, which then supplies the escapement with a more consistent amount of energy. Depending on the design, this recharge can occur every second, several seconds, or at another predetermined interval. Watching the mechanism recharge can create a fascinating mechanical rhythm—almost like a tiny watch inside the watch repeatedly winding itself.

The concept is much older than the modern wristwatch. Remontoire mechanisms appeared in precision clocks and regulators centuries ago, where maintaining consistent force was essential to achieving exceptional accuracy. Eventually, extraordinarily skilled watchmakers miniaturized the principle for portable watches and, later, wristwatches. Doing so requires sophisticated engineering because the mechanism must repeatedly store and release energy without disrupting the very precision it is intended to improve.

Today, the remontoire remains an uncommon and prestigious complication. Unlike complications that simply display additional information, its purpose is fundamentally about improving the quality of the watch’s timekeeping. It’s a beautiful example of high horology solving a mechanical problem with more mechanics: when the power supply isn’t perfectly constant, build a tiny mechanism that continually evens it out.

💡 Did You Know?

A remontoire isn’t the same thing as a fusee-and-chain constant-force system. Both address variations in mainspring torque, but they attack the problem differently: the fusee compensates for changing mainspring force through variable mechanical leverage, while a remontoire periodically receives energy from the going train and delivers it onward in controlled increments.

Category: Fun Quirk

Disclaimer: Every effort has been made to keep these watch facts accurate, but the world of horology is full of myths, disputed stories, and fascinating trivia. Consider these facts a starting point for discovery rather than the final word. If you have corrections or additional insights, let us know—we’re always happy to keep the record ticking in the right direction.

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