31 Jan '16, 8am
You see, as though all that dizzying engineering weren't enough, Greubel Forsey has added a constant force mechanism to the differential. Exposed through a little aperture set into the caseback side of the movement, a wheel and a spring on the underside of the differential can be spotted. This spring, that may look a bit like a hairspring to the untrained eye, is responsible for releasing its energy into the differential, all the way through to the double escapements. This is done so as to counter the effects of waning torque delivered by the two, series-coupled mainspring barrels of the movement as they near the end of their 72-hour-long power reserve. The four-minute counter that we mentioned just above is linked to this bottom gear of the constant force mechanism as it takes it four full minutes to make a complete rotation.