Clock Repairs for Every Type of Clock
Atmos is the brand name of a mechanical torsion pendulum clock manufactured by Jaeger-LeCoultre in Switzerland. This clock does not need to be wound manually. It gets the energy it needs to run from temperature and atmospheric pressure changes in the environment, and can run for years without human intervention.
The clock is driven by a mainspring, which is wound by the expansion and contraction of liquid and gaseous ethyl chloride in an internal hermetically sealed metal bellows. The ethyl chloride vaporizes into an expansion chamber as the temperature rises, compressing a spiral spring. With a fall in temperature the gas condenses and the spiral spring expands, winding the mainspring. This motion constantly winds the mainspring. A temperature variation of only one degree in the range between 15 °C (59 °F) and 30 °C (86 °F), or a pressure variation of 3 mmHg, was calculated to provide energy for two days’ operation for an early prototype, while for a more recent Atmos 540 model the corresponding value has been computed as 4.3 days per °C.
To run the clock on this small amount of energy, everything in the Atmos must be as friction-free as possible. For timekeeping it uses a torsion pendulum, which consumes less energy than an ordinary pendulum. The torsion pendulum has a period of precisely one minute; thirty seconds to rotate in one direction and thirty seconds to return to the starting position. This is thirty times slower than the 0.994 m (39.1 in) seconds pendulum typically found in a longcase clock, where each swing (or half-period) takes one second.
This particular model is prone to this and we see it quite often.
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