Remontoirebased

Remontoire-based refers to a class of timekeeping mechanisms that incorporate a remontoire, an energy reservoir, to deliver a constant amount of energy to the escapement. The goal is to compensate for torque variation from the primary drive (usually a mainspring or equivalent), which otherwise causes the escapement and rate to drift as the power source unwinds.

In a typical remontoire-based design, a small secondary power source—such as a short-duration spring or a weighted device—is periodically wound by the main train. This reservoir then releases energy to the escapement in fixed, regular increments. The result is a near-constant impulse to the escapement over the interval between recharges, improving isochronism. The remontoire is subsequently reset by the gear train, maintaining a cycle of energy storage and release that decouples the escapement from large fluctuations in the driving torque. Designs vary in where the remontoire sits in the movement, how it is wound, and whether energy is delivered directly to the escapement or via an intermediary wheel.

Historically, the remontoire concept is associated with late 18th and early 19th-century horology, most notably with Abraham-Louis Breguet’s remontoire d’egalite. It was used in precision clocks and marine chronometers to enhance accuracy. In modern practice, remontoire-based devices remain relatively rare but are employed by select makers to achieve superior long-term stability and isochronism in mechanical clocks and high-end watches, as an alternative or complement to other constant-force solutions such as fusee-and-chain.