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Omega Co-axial Training

by Jordan Ficklin

The long awaited details from my Co-Axial training at Omega, USA.

co-axial5First things first, if you haven’t taken the time to look at a Omega’s (Geo. Daniel’s) Co-axial escapement you are in for a treat. The principles of servicing the swiss lever escapement do not apply to the co-axial escapement, don’t try and apply them.

To understand the co-axial escapement we should check out a model: For the best watch related animated models on the internet always check out clockwatch.de. For this model we want a model of the George Daniels’ Extra Flat Co-Axial Escapement. The description of the escapement on the linked page is also very good. You might also check out the description at Alliance Horlogere or this one at Omega.

First, some theory. Then, the practical stuff.

If you take a look at the co-axial escapement you’ll notice its very different. First, it has 3 jewels on the pallet fork and one on the balance wheel. In the swiss lever escapement each of the jewels on the pallet fork serve two roles. First, they receive the impulse from the escape wheel, second they lock the gear train until the balance returns to unlock it so it can receive the next impulse. — In the co-axial escapement these roles are separated. There are two jewels whose only function is to receive impulses and two jewels just to perform the locking action. This isn’t the big deal though! This seems to be a side effect of achieving what George Daniels set out to do.

In the Swiss Lever Escapement the impulse is delivered to the balance via the pallet fork by way of a sliding action where the escape wheel slides across the impulse face of the jewel. The escape wheel tooth moves the direction of its force being applied tangential to it’s circumference, but the pallet fork moves away almost at a right angle to this force, making it about the least efficient transmission of force possible.

In the coaxial escapement the impulse is delivered from the coaxial wheel to the pallet fork in a radial fashion. As the impulse is delivered to the impulse jewel, it moves in the same direction, receiving almost all of the energy and with very little sliding action. In the opposite direction the impulse is received directly by the impulse jewel attached to the balance.

Because there is no sliding action in the coaxial escapement there is no need for lubrication. Because there is no lubrication to break down the timekeeping will be more consistent over the service interval – which Omega claims is longer due to the use of synthetic oils, and their absence in the escapement.

Now, the practical information: Please take note, what I am about to tell you is not sufficient information to get you started servicing coaxial movements. This information is intended to help you see that there are in fact some real reasons why hands-on training would be a wise investment before tackling these watches.

First, The “oil-free” coaxial escapement has a little oil on it. Yes, I know, what about what I said above. The impulse jewels are left dry, there is no need for the oil there. The locking jewels have a very, very, very small amount of oil on them to help cushion the locking action. (To gauge the proper quantity of oil, it is applied under 50 power magnification.) This oil acts, not as a lubricant, but as a cushion to absorb part of the shock from the locking action. Leaving this oil off does not affect the timekeeping of the watch, but it will likely result in damage to the upper coaxial wheel teeth over time. . . . But Geo. Daniels didn’t put any oil on his movements? The coaxial wheels in his watches are made from a Gold alloy which is softer (and springier?) than the steel used by Omega. This material choice serves to absorb the extra shock without the need of a “hydraulic cushion.”

Second, didn’t Omega have issues with the first coaxial movements? Yes, they did. The 2500A had some critical problems, which have been resolved. The tolerances are so tight on these watches that the slightest shift in the escapement will result in the watch coming to a stop. The 2500A allowed the pallet fork to shift slightly when it received a shock. Because of this many of the 2500A movements were replaced with “B” movements making the “A” series all that more collectible. The “B” movement has a sturdier pallet bridge (among other changes). In their most recent caliber Omega has implemented a new shock system which limits side to side movement of the balance wheel when it receives shocks. Because one of the impulse jewels is on the balance a shift at the wrong moment will allow the coaxial wheel to pass by the impulse jewel without delivering the impulse and causing the watch to stop. My opinion is that Omega has finally figured out how to make reliable coaxial movements, but they will continue to make improvements for many years to come.

Third, you may be able to time your coaxial watch on a conventional timing machine but the amplitude readings will probably be wrong. Modern timing machines from Witschi have special programs for coaxial escapements. Calibers which operate at 28,800 bph will correctly display their timing, even on an old Vibrograph B200, but amplitude numbers will be incorrect, even if you set the appropriate lift angle (30 or 38 degrees depending on the caliber.) Newer, 25,200 bph calibers are more difficult to time because older timing machines do not have a setting for this frequency. My Witschi Professional will allow me to adjust the rate to any frequency, but it takes about 15 minutes to cycle up to 25,200 from 19,800 or down from 28,800 (the nearest frequencies.) My New Tech Handy II (Quartz Tester) automatically recognizes the frequency, but it doesn’t have an adjustable microphone so it is difficult to check different positions.

Fourth, Drop and Lock may be way different on the entry stone, than they are on the exit stone. This is fine. Drop may be very shallow, this is fine. The tolerances are so tight that rather than adjust stones that don’t lock correctly, or which have been knocked loose, you should replace the fork.

Fifth, IMPORTANT! do not reverse the travel of the balance wheel until all the actions of the escapement have taken place. Unlike with the swiss lever escapement if you reverse the direction of travel of the balance in the middle of the escapement action you WILL DAMAGE the pallet stones.

Sixth, if you have a modern timing machine which accommodates the coaxial escapement the amplitude can be very low on newer 25,200 bph models. Check the Omega technical information for acceptable ranges.

De Ville Hour VisionSo, where do I find the coaxial escapement? Omega is putting it in a lot of watches these days. The have developed their calibers 2500A, B, and C -all based on the ETA 2892. It is in caliber 2627 and 2628 and their chronograph caliber 3313. They have installed in a Valjoux 7750 in an Olympic edition model introduced at Beijing (Omega caliber 3888). It is in the new double barrel calibers 8500 for men’s 8520 for ladies and 8601 with annual calendar. I believe it was also placed in a tourbillon (but I might be wrong about this one).

My overall impressions. They’ve finally figured out how to mass-produce the coaxial escapement and it offers some minor improvements over the swiss lever escapement, but nothing drastic. As a watchmaker, it is very interesting to work on, and it boggles my mind how somebody could develop this from an idea in their head. Don’t be looking for a J.Peter escapement any time soon.

11 Comments

  1. sdchew
    Posted May 5, 2010 at 10:18 am | Permalink

    What are your thoughts on the function of the dual barrel in the 8500? More uniform torque delivery into the co-axial escapement?

  2. J.Peter
    Posted May 5, 2010 at 11:49 am | Permalink

    The function of the dual barrel is to allow the barrels to unwind faster and have less torque at the escapement. The co-axial escapement doesn’t need a whole lot of torque. Less torque may allow them to remove all oil, including the cushioning oil for locking. The end result is only a power reserve of 60 hours, despite having two barrels, but their intention is to reduce torque, not increase the power reserve.

  3. sdchew
    Posted May 5, 2010 at 5:21 pm | Permalink

    thank you for the reply. Hmm, your reply does give me some food for thought.

    When I first read about the 2500 series problems (watch stopping, jamming), many folks commented that a hard tap to the watch could restart it. My initial thoughts about it was insufficient torque delivered to allow it to ‘push’ out of the situation.

    Some folks also speculated about this when the 2500C beat rate was reduced from 28,8. The train of thought was reduction in speed allowed for more torque and less ‘jamming’. Could you share your thoughts on why the beat rate was reduced?

    On another hand, I also suspected manufacturing tolerance issues or a marginal design (slight variation or shifts in assembly would cause it to fail). This would explain why some 2500 users have entirely no problem with the watch but a few folks did.

    The reduction of torque comment however, does make sense in the light of early reports from failing 33xx chrono movements which reportedly had parts which were bent and damaged.

    Thank you for sharing your insights.

  4. J.Peter
    Posted May 6, 2010 at 7:59 am | Permalink

    The co-axial escapement is not a great self starter, like the swiss lever although it does self start with enough wind. A little shake is sometimes necessary to get it going.

    The reduced beat rate to 25,200 is a result of a compromise. George Daniels has long said that 28,800 was too high a beat rate for the co-axial. All the ones he has produced have been lower beat rates. Apparently Omega & their counterparts at ETA are starting to realize that as well. Remember that the oil on the escapement is to cushion the large locking impact. Lowering the beat rate can help reduce the strength of that impact.

  5. sdchew
    Posted May 6, 2010 at 9:45 am | Permalink

    Thanks J.Peter for your insights. Greatly Appreciated

  6. Posted May 31, 2010 at 2:16 pm | Permalink

    Thanks for sharing your insights from the course, J.Peter. I am really glad that Omega has finally tailored a movement to the escapement, as opposed to trying to squeeze it into the 2892. I am convinced that having a dedicated pinion for the escape wheel will offer much better success than the hybrid wheel-pinion used in the 2500A-C and other early models.

    It really is mind boggling that George Daniels was able to conceive this design, especially when you consider the fact that he did it on paper – without a computer – more than 30 years ago. He offers an interesting insight into his thoughts and process in his book The Practical Watch Escapement – if you can get your hands on a copy as they’re hard to come by. He covers much of the same information on escapements in Watchmaking, though, especially regarding the co-axial escapement and the text is almost word-for-word the same between the two books.

  7. L. Alex
    Posted June 11, 2010 at 9:21 pm | Permalink

    I have a co axial 2500 not sure if it is a,b or c..
    Omega Constellation.

    I dropped it on a wooden floor and it landed on its side. It was not a huge fall but the watch has since that moment stopped moving. I have been moving it in circles etc for many many minutes..No result.

    Do you recommend me giving it a similar shock on a specific side? What would you do if you received this watch to repair?
    Any of your thoughts would be extremely helpful & appreciated.

    L

  8. J.Peter
    Posted June 12, 2010 at 8:10 am | Permalink

    Dropping a watch on a wooden floor is a huge fall when you consider that the pivots of the balance are approximately 0.10 millimeters in diameter. I would NOT give it another shock. I would have a watchmaker look at it. It may be a simple fix, but there could also be broken parts which need to be replaced.

  9. Glenn
    Posted June 24, 2010 at 10:10 am | Permalink

    With the Co-Axial running a bph 25,200 versus a 28,800, does the second hand sweep as smoothly? Is this one of the reasons why Omega can extend the warranty to 3 years now? Is accuracy affected because of the lower bph? I know that Omega claims COSC compliance, but it is pretty wide range. I guess my question would be is the Co-Axial @ 25,200 bph as accurate as a movement running at 28,800 bph?

  10. J.Peter
    Posted June 30, 2010 at 8:24 am | Permalink

    Definitely just as accurate a watch, if not more so than the other because of the increased reliability.

  11. Ravi
    Posted September 15, 2011 at 9:46 am | Permalink

    hi, Peter(or anybody who can answer my question)

    i am planning to buy omega seamaster(james bond) 1500 caliber watch…. are there any known issues with this watch

    i am planning for this watch because i read that it increases the service interval to 7-8 years is this true

One Trackback/Pingback

  1. [...] in the form of cataracts, resulting in blurred vision. Imagine trying to flatten a hairspring or lubricate the escapement of a co-axial movement while in a fog. It’s not going to happen. Our eyes are unquestionably our most valuable set [...]

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