The coaxial escapement is a type of modern watch

escapement An escapement is a mechanical linkage in mechanical watches and clocks that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands. The impulse action transfers energy ...

mechanism invented by English watchmaker George Daniels in 1976 and patented in 1980. It is one of the few watch escapements which have been invented in modern times and is used in most of the mechanical watch models currently produced by

Omega SA Omega SA is a Swiss luxury watchmaker based in Biel/Bienne, Switzerland. Founded by Louis Brandt in La Chaux-de-Fonds in 1848, the company formerly operated as ''La Generale Watch Co.'' until incorporating the name ''Omega'' in 1903, becoming ...

History

During the

quartz crisis The quartz crisis was the upheaval in the watchmaking industry caused by the advent of quartz watches in the 1970s and early 1980s, that largely replaced mechanical watches around the world.

, 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 The lever escapement, invented by the English clockmaker Thomas Mudge in 1754 (albeit first used in 1769), is a type of escapement that is used in almost all mechanical watches, as well as small mechanical non-pendulum clocks, alarm clocks, an ...

with some features of the detent escapement. One of the few advances in escapement design which have been adopted since the invention of the lever escapement by Thomas Mudge in the 18th century, the coaxial escapement functions with a system of three pallets that separate the locking function from the impulse, avoiding the

sliding friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of ...

of the lever escapement. This makes lubrication of the pallets theoretically unnecessary Archived article page
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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 impact corrosion.

Critical virtue

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 escapement gear. 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 (though many factors influence this including lubricant aging) and greater accuracy over time.

Commercialization

The escapement was commercialized in 1999 by

when it introduced the first mass-produced watch incorporating the technology. It is the only escapement other than the Swiss

that is produced on an industrial scale. When it first came to the market as the Caliber 2500, it had an oscillation rate of 28,800 beats per hour (8 beats per second), considered a "hi-beat" movement. But the rate was reduced to 25,200 beats per hour (7 beats per second) 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 (at the escape teeth and pallets). Higher beat movements produce increased speed and pressure at these critical surfaces."Zbinden, H., Zbinden, H., Of Larger Balances, High Beat and Important Oils, TZ Classics No. 1591, Timezone, Dec. 26, 2000, quoting Odets, W.

References

External links

Description and animation of Omega's co-axial escapement

A technical perspective The co-axial escapement
by Xavier Markl
Questions in Time column about the history leading to the co-axial escapement
by Professor J. C. Nicolet
Clear images, and an animation, of the co-axial escapement
by Siméon Lapinbleu

Mark Headrick's Horology Page Escapements