Atmos Clocks
Atmos clocks, due to their unusual design and very delicate construction, should only be repaired by a specialist.
Believe me, It will work out "cheaper" in the end
The latest model in the Atmos range is the cal 540, (the cal550 series is based on the 540's design).
A few collectors are not too fond of this model because they consider that the changes made by Jaeger LeCoultre are too radical
and therefore the design is now a bit too far removed from the original.
But, in recent years, the cal 540 has become the most sought after model.
Maybe, because it is the youngest model and therefore less likely to need expensive parts and the finish has suffered less from the passing of the years.
Atmos, cal 540(left) and cal 528(right). Comparing the construction of the latest Atmos cal540 with the earler 528 model.
The construction is lighter, the wheels are lighter and in the very latest models the new type of mainsping, as well as the bellow construction, are a major improvement.
The new mainspring goes some way to ease the problem of variation in power, found in earlier models.
The bellow is smaller and seems more flexible. The bellow housing is stronger, therefore more efficjent and reduces the likelyhood of cracked bellow housing.
Technically, the benefits outweight the need to mantain "originality", as it produces a much more reliable balance amplitude.
Alhough I believe, that there could be another aspect to the cal540: From my experience as a repairer, this new model, in some cases, may require servicing at shorter intervals. I have personally come across a few cases where this model needed servicing after only 10years or even after 5 from new. This was very surprising to the owner expecially if they also owned an older caliber, which had not needed any attention for 25-30 years.
Of course, I do not say that this would be the case for all cal 540 clocks.
A good service and fault-correction, with great attention to details, should give this model the longer trouble-free period that it is capable of.
The balance amplitude is a good indicator of whether your clock is in need of a service. Watch this short video
Please be aware that a cal 540 that has been "mishandled" by a repairer will cost you a lot more to put right
Atmos, The clock of Presidents
W. Churchill, J.F.Kennedy and C. De Gaulle with Atmos clocks in the background
Article found in an old magazine
Please click on the images to read the full article
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Comparing the Cal540 with the Cal519, 526 or 528 movements
From the pictures you can clearly appreciate the differences.
In the cal528 (right), the extra plate accomodates the heavier barrel and the first intermediate wheel.
All the dimensions in the cal540(left) are smaller.
The movement, the "winding" spring, the bellow and all the case dimensions are all about 1cm smaller.
BELLOWS
When an Atmos stops working, in 95% of the cases the failure is readily blamed on a faulty bellow, while I find that in less than 20% is the bellow at fault.
An Atmos specialist will correctly diagnose the likely cause of the problem.
Bellow comparison: Atmos cal540 (left), Atmos cal528 (center), Atmos cal519 (right)
The cal540 bellow case has a bayonet fitting and measures 120mm dia.
Cal528 and cal519 have larger bellows, 130mm dia. They are attached with two and four nuts respectively.
Bellows can vary: the image below shows two similar ones which have different dimensions when fully contracted.
Below, the LEFT AND CENTRE IMAGES illustrate how a faulty bellows would look like at room temperature, flat or half deflated.
RIGHT IMAGE: bellow in good condition.
Of course, bellow expansion will also vary according to temperature and air pressure, .
This type of bellow cannot be refilled or repaired
I am interested in purchasing any Atmos clocks for spares,
If I can, I will supply second-hand Atmos parts to other repairers, when available.