The power transmission with fusée (fusée-and-chain transmission) ensures a constant driving force in the movement.
The gradual discharging of a mechanical watch causes a loss of amplitude and a corresponding loss of precision. On the contrary, with a fusée-chain transmission system, the driving force remains entirely stable throughout the duration of the power reserve. Whereas the spring at its heart imparts its strength to the barrel, the helicoidal shape of the fusée – stemming from a complex calculation performed specifically for the mainspring – compensates for the variations in force of the barrel that will progressively occur.
The French term, cabestan is often associated with fusée-and-chain watches as it refers to the capstan or winch that collects the chain. This term was adopted as the name of Swiss watchmaker Cabestan, which launched a watch based on this concept in 2008.
Examples of watches using this design principle: