Greubel Forsey Différentiel d'Égalité

Greubel Forsey's fifth fundamental invention, developed through their EWT (Experimental Watch Technology) laboratory. Features a constant force device based on a spherical differential that provides the same constant force to the escapement regardless of mainspring tension. This solves the typical problem where the mainspring delivers different amounts of force depending on how much potential energy it retains. The mechanism ensures consistent amplitude and timekeeping accuracy throughout the entire power reserve.