The escapement is the regulating heart of a mechanical movement: it receives energy from the gear train and distributes it to the balance in controlled impulses, allowing time to be measured. Without it, the movement would spin freely, unmeasured. The term escapement is standard in English and has become the dominant technical term worldwide.
The dominant type in the twentieth century is the Swiss lever escapement, robust and relatively simple to produce. But it has an inherent limitation: the impulse to the balance passes through rubbing surfaces that wear and require periodic lubrication. George Daniels solved this problem in 1975 with the Co-Axial, which separates the impulse function from the locking function, drastically reducing friction. Omega adopted it in production in 1999; today it is fitted to all the manufacture's modern calibres. The idea is simple, the execution is not: it took nearly a quarter century before someone industrialised it.
Lubrication has always been the weak point of any lever escapement. Silicon changed the equation: lightweight, antimagnetic, extremely hard and chemically inert, it neither absorbs nor disperses oil. Ulysse Nardin was among the first to use it in real-world production with the DIAMonSil, where the silicon base is coated with diamond; Rolex responded with the Chronergy, in nickel-phosphorus processed by LIGA, which improves energy efficiency by 15% over the classical lever escapement. Grand Seiko developed the Dual Impulse, paired with a free balance, pushing frequency to 5 Hz with a geometry that improves shock resistance. Nomos has its own Swing System, regulated in six positions, present across the entire in-house collection.
The natural double-wheel escapement, originally conceived by Abraham-Louis Breguet, is another path: two escapement wheels transmit impulse directly to the balance without passing through the pallet fork, gaining around 30% efficiency compared to the Swiss lever. Kari Voutilainen carries it forward in his watchmaking tradition; each example requires around 565 hours of work. Urban Jürgensen instead used Derek Pratt and Mojon's detent escapement, a type designed for marine chronometers, extremely sensitive to shocks but extraordinarily clean in its impulse.
The constant force escapement, or remontoire, is not strictly a different escapement but an interposed device: a secondary spring, rewound at regular intervals by the main train, delivers constant energy to the balance regardless of power reserve. A. Lange & Söhne uses it in the Zeitwerk to protect the balance from the harsh impulses of the disc-change mechanism. The opposite phenomenon, knocking, occurs when the balance amplitude is excessive for the pallet fork geometry: the impulse pin strikes the fork poorly and efficiency drops. It is something you feel at the workbench, not something you read only in books.