A Simple Explanation Of The Omega Co-Axial Escapement

One of the first brands you hear about when you get interested in watches for the first time is Omega, and one of the first things you hear about Omega is that the brand is the sole user of the co-axial escapement (with one major exception).

The co-axial escapement was originally invented by British watchmaker George Daniels in 1976, with a patent granted in 1980. After many years of showing his escapement to different watch brands, including Rolex, and Patek Philippe, Omega finally decided to produce co-axial escapements in series, with the first co-axial escapement watches launched in 1999.

The co-axial escapement is now used in virtually all Omega watches.

Often, explanations of the co-axial become complicated and intricate (I have written very long stories about the escapement many times). Here, I’m going to try to follow a saying from Einstein: Everything should be made as simple as possible, but not simpler.

First, we need to know, at its most basic, what an escapement is. Then, we can look at two high performance escapements, and finally, we can see how the co-axial escapement is designed to use the best features of each.

An Escapement Counts The Beats, And Also Drives The Balance

The co-axial escapement, like all escapements, does two things: it makes it possible for a watch to count the number of swings of the balance wheel, and it keeps the balance wheel swinging. If a balance swings eight times per second, this equals eight ticks of the watch. If the gear train, which drives the escapement, is set up so that the gear for the minute hand makes one full rotation after 28,800 ticks, you have a watch; all you have to do is have the same once-per-hour gear turn another gear once every 24 hours.

(For a look at the relationship between beats/vibrations per hour, check out “What ‘High Beat’ Means In Watchmaking.”)

The Quartz Crisis And The Birth Of The Co-axial Escapement

The co-axial escapement exists basically because a stubborn British watchmaker was angry about quartz. Daniels would say, in 1999, in an interview with Norma Buchanan in American Watch magazine, “I was furious with ‘electricians. I was angry with the way they just strode through the watch world saying, ‘This is the future.'”

Dr. George Daniels

“Electricians” was his mocking term for the proponents of quartz watch technology. Creating the co-axial escapement was a way of showing the world that mechanical watches were still relevant, and that watchmakers could still invent.

The co-axial escapement was influenced by the earlier work of Breguet, an American-German watchmaker named Fasoldt, and by insights from Daniels’ contemporary, the watchmaker Derek Pratt.

Two Escapments That Were Combined In The Co-Axial

An escapement turns the one-way rotation of gears into the two way rotation of the balance. In the lever escapement, which is used in almost every watch except Omega’s co-axial watches, the last gear in the gear train flicks a pivoting lever back and forth. The lever gives the balance a brief push at each swing of the balance.

The last gear in the gear train is called the escape wheel. The lever has two arms at one end, which take turns stopping an escape wheel tooth, or pushing it:

If you look closely, you can see that at each swing, the lever is pushed one way or the other, by the slanted tip of one of the escape wheel teeth. However, the push happens when the tip of the tooth rubs, or slides, against the ruby jewel (in red). This creates friction, so, in order to minimize wear and increase efficiency, watchmakers use oil to make the escapement run better.

The problem with this is that oil breaks down over time, and this gradually reduces the strength of the push on the balance, which makes the watch gradually less accurate.

There is, however, an escapement used in high precision ship’s chronometers, which does not have this problem.

This is the famous detent, or chronometer, escapement. In this escapement there is no lever. Instead, there is a weak spring which holds the escape wheel in place. At each swing of the balance, the balance pushes that spring aside briefly, and the escape wheel is free to give the balance a push. The escape wheel pushes directly on the balance, so there is no lever.

No oil is needed as there is no sliding friction. However, because the spring is weak, the detent escapement is very easily disturbed by shocks, which can knock the spring out of the way and allow the gear train to spin out of control.

Both the lever escapement and the detent have good and bad points:

The Lever Escapement: shock resistant and reliable, but accuracy decreases as oil wears out.

The Detent Escapement: no oil needed, but very vulnerable to physical shock.

It would be great if you had some sort of escapement that combined the advantages of both and the disadvantages of neither, which is what Daniels designed the co-axial escapement to do.

The Co-Axial Escapement

The co-axial escapement is called this because it has two escape wheels, stacked on the same axis. Here is Omega’s version:

As you can see, there is a lever, but the escape wheel doesn’t look anything like the one in the lever escapement. This is because it’s designed to push directly on the balance in one direction, like the detent escapement (the job of the escape wheel with the longer arms) and to give impulse through the lever when the balance swings in the other direction (like the lever escapement).

The design of the escapement also means the sliding friction of the lever escapement is absent, and so is the delicacy of the the detent escapement.

Co-Axial Escapement FAQ:

Is it true that no oil is used in the Omega Co-Axial escapement? Not entirely, although it has a different purpose – Omega uses microscopically small amounts of lubricant to cushion the impact of the escape wheel teeth.

What’s the biggest benefit of the Omega Co-Axial escapement? The escapement lets the watch go for longer between service intervals, since breakdown doesn’t affect precision. Also, accuracy should be more consistent between service intervals.

How long can a watch with a Co-Axial escapement go between services? Omega recommends 5-8 years, compared to the 3-5 year industry standard, for a watch in regular use.

Do I need to have a watch with a C0-Axial escapement serviced at all, then? Yes. Remember that all watches have oils, greases, seals, and gaskets which need to be replaced regularly for several reasons, including maintaining water resistance.

If I had to put the whole thing in an elevator speech, I think it would be: The co-axial escapement was designed in response to the Quartz Crisis. It showed that mechanical watches could still be improved, and it combines the oil-free high precision detent escapement, with the shock resistant and reliable lever escapement. 

There is one other place you can find co-axial escapement wristwatches: in the work of Daniels’ only apprentice, the watchmaker Roger Smith, who continues to refine the escapement, and whose watches are in such high demand that they have become, essentially, unobtainable. Roger Smith went on record with me years ago on the use of lubricant in the co-axial escapement, saying:

“We apply lubrication to our single wheel teeth, as did George [Daniels]. This prevents a build up of oxide where the tooth impacts the jewel. Interestingly, this impact effect was common in the detent escapement and lubricants were applied to combat the effects. The key thing to remember though is that the rate of timekeeping will not be affected as the condition of the lubricant deteriorates and this is due to the impulse being delivered through a simple pushing action as opposed to the highly inefficient sliding action found in the lever escapement.”

It’s fascinating (to me anyway) to think that if it weren’t for George Daniels’ frustration, at the height of the Quartz Crisis, with electronic horology, and his determination to prove the “electricians” wrong, the co-axial escapement as it exists today at Omega might not have been developed at all. Of course, it wasn’t invented in a vacuum – many preceding watchmakers had explored similar ideas, as well as some of Daniels’ contemporaries.

It is not a perfect solution, of course; those don’t exist in practical mechanics. But it represents a major moment in the development of modern watchmaking, and a connection to a moment when a lone craftsman showed that even electronic industrialization on a major scale can’t make an individual obsolete.

The 1916 Company is proud to be an authorized retailer for Omega watches.

For an in depth technical analysis of the detent escapement, and its role in the development of the co-axial escapement, check out my story, “The Detent Escapement In Wristwatches” at Revolution Magazine. And to find out more about Master Chronometer certification, see, “METAS Certification: What It Takes To Be A Master Chronometer.”