During the quartz crisis, English watchmaker George Daniels accepted a commission from American industrialist and watch collector Seth G. Atwood to create a timepiece that would fundamentally improve the performance of mechanical watches. As a result, Daniels invented the coaxial escapement in 1974 and patented it in 1980. The Atwood watch for Seth G. Atwood was completed in 1976.
Technical overview
The coaxial escapement is a modification of the lever escapement with some features of the detent escapement. Considered by some to be one of the most significant horological advancements since the invention of the lever escapement, the coaxial escapement functions with a system of three pallets that separate the locking function from the impulse, avoiding the sliding friction of the lever escapement. This makes lubrication of the pallets theoretically unnecessary and thereby minimizes one of the shortcomings of the traditional lever escapement. In practice, a small amount of lubrication is used on the locking and impulse surfaces of the pallet stones, reportedly to minimize impactcorrosion.
The critical virtue of the Daniels escapement is the virtual elimination of the sliding friction component; i.e., the sliding of the pallet stones over the teeth of the escape wheel. What little sliding friction remains is due to the impossibility of maintaining an exact tangential geometry throughout the duration of an impulse.
Radial friction vs. sliding friction
By utilizing radial friction instead of sliding friction at the impulse surfaces the coaxial escapement significantly reduces friction, theoretically resulting in longer service intervals and greater accuracy over time.
Commercialization
The escapement was commercialized in 1999 by Omega SA when it introduced the first mass-produced watch incorporating the technology. It is the only other escapement produced at industrial scale, other than the Swiss lever escapement. When it first came to the market as the Caliber 2500, it had an oscillation rate of 28,800 bph, considered a "hi-beat" movement. But the rate was reduced to 25,200 bph in the Caliber 2500C. "While Daniels has recognized the advantages of higher beat movements, he has also noted that they aggravate the problem of sliding friction in the escapement. Higher beat movements produce increased speed and pressure at these critical surfaces."
