Ever wonder about the condition of an Atmos clock offered for sale?

Most people really like the gold (24k plated) and glass Atmos, but unless they already own one and understand it they are hesitant to purchase a used Atmos, and with good reasons.  First, a used Atmos is often quite expensive – though far from the cost of a new model.  Then there is the concern about the near-impossibility of finding parts.  Additionally, only a very few horologists – whether clock or watch specialists – have the proper skills, tools, experience and motivation to correctly service or repair the Atmos.  I know this because owners ship me their Atmos clocks from around the country.


Maybe what to look for should come with a caution about how to proceed, especially if your intent is to have an Atmos that looks cosmetically pleasing for many years.  Do not handle any of the plated surfaces, on the case or inside, with bare hands.  Atmos clocks have thin plating, typically gold, with a protective lacquer cover.  Contact with the skin will result in non-removable stains.

  • Is it running, and if so, has it been running long or just made operational for sale?
    1. The balance on a good Atmos should revolve more than 360⁰ in each direction, but not more than about 500⁰.
    2. It’s challenging with the dial in place, but you need to observe the condition and action of the fragile pallet fork at the top of the movement.
      1. Is the fork bent or apparently mis-shapen?
      2. When the fork goes back and forth, is the action smooth, with a very slight “jump” as it begins moving, but without a “bump” as it passes its center point?
      3. At each end of its stroke is the spacing between the fork and the banking pins very nearly identical?
      4. Does the roller appear to stop at the same position on each side?
    3. Everyone seems concerned about the condition of the bellows (motor) on an Atmos, so how can it be determined?
      1. On the left, looking from the front is a cam wheel between the plates with a gold chain coming off the top and a small coil spring off the bottom.  If the chain is retracted into the motor enough that the spring is quite visible under the cam wheel, chances are the bellows is collapsed – but not always.
        1. In servicing many more than 100 Atmos clocks I have found fewer than two dozen failed bellows.  On virtually every one, however, the mainspring was either dry or contaminated and not functioning optimally.  This not surprising, as LeCoultre recommends service every 20 years, and I see non-serviced Atmos from 50 or more years ago still operating. If the mainspring is not winding the chain might not retract properly.
        2. In unusual circumstances – the practice seems somewhat fraudulent, but you will have to make a determination – a seller may manipulate the chain winding system to put tension on the mainspring and make the Atmos run.
    4. While not a major concern, the position of the fast/slow adjustment (a lever at the top of the plates on all but very early Atmos) should not be set excessively either fast or slow, as this could indicate operating problems.
    5. If you move the Atmos, either to relocate it in place or to bring it home, lock it before moving it.

Enjoy the quiet beauty of your Atmos clock with its 15-jewel movement that lives on air, is very reliable, and with minimal and proper care will outlast you.  LeCoultre says it will still be operating some 600 years from now.

Ed O’Brien
(407) 694 8228

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