The co-axial escapement in the new OMEGA calibres is used in conjunction with a free sprung-balance and its function differs considerably from that of a conventional lever escapement with index. This mechanism calls for closer examination to fully appreciate the benefits it offers in terms of reduced friction and increased stability of rate in a watch for years at a time. The escapement consists of an intermediate wheel A (see Figure 1 below), a coaxial double wheel B comprising an escapement pinion C and an escapement wheel D, a lever E with three ruby pallet stones F, G and H and a balance roller I carrying a ruby impulse stone J and a ruby impulse pin K. It is essential in all modern escapements that the energy is transmitted to the oscillator by impulses in both clockwise and anti-clockwise directions. In the co-axial escapement, the clockwise impulse is delivered to the oscillator by the escape wheel D engaging the ruby impulse stone J. The anti-clockwise impulse is delivered by the teeth of escapement pinion C by engaging the impulse stone G. After each impulse, the escape wheel is locked stationary on the locking pallets F and H, allowing the balance to complete its movement. The main advantage of this new mechanism becomes clear when it is compared with the lever escapement. In the case of a lever escapement, as we can see in Figure 2 opposite, the wheel tooth slides along the sloping surface of the pallet from position A to position C, driving the pallet in direction B. This sliding motion causes considerable friction and requires optimum lubrication for the escapement to work properly. However, lubricants deteriorate very quickly and climatic changes (temperature, humidity, etc.) compromise the watch's stability of rate.The co-axial escapement, by contrast, transmits its energy by using tangential forces transmitted from the radial movement of the components. The escape wheel tooth falls on the side of the impulse stone in position A, pushing the pallet through position B until it reaches the end of the pallet in position C (see Figure 3). This very brief sliding movement considerably reduces contact between the surfaces and, consequently, friction in the escapement. The result is an escapement that is fully comparable to that of a pinion engaging the teeth of a wheel, which means that it is not reliant on lubrication (a thin protective film on the end of the escapement wheel tooth is enough to prevent wear) and ensures the watch's stability of rate over long periods of use. The co-axial escapement in the OMEGA calibres is used in conjunction with a free sprung-balance. The watch's rate can be adjusted by modifying the moment of inertia of the balance by means of two gold regulating micro-screws embedded in the balance. This mechanism overcomes the disruptive effects of contact between the balance-spring and the index pins. It helps to ensure that the stability of rate offered by the co-axial escapement is maintained over long periods of use. The combined benefits of the co-axial escapement and the free sprung-balance make the new De Ville Co-Axial Escapement movements superior chronometers, their classic style marvellously complementing the extraordinary heart that beats within. These prestigious OMEGA timepieces are setting new milestones in master watchmaking for the third millennium.
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