Atmos main spring

[ALR guy]

Wondering what the purpose of the "brace" is in an Atmos clock mainspring assembly.

 

[etmb61]

Just like in watches, it relieves the strain on the mainspring connection to the barrel.

 

[ALR guy]

Goodness! Thanks for the swift reply. Haven't tried my hand at watch repair so the strain issue is unfamiliar to me. Can you embelish on that for me?

 

[etmb61]

Watch mainsprings are small enough that aggressive winding can break the spring or the barrel hook where the spring is attached. The brace in the barrel is an attempt to prevent that. Atmos is basically a self winding watch. The motor winds the mainspring whenever the temperature drops whether it needs it or not. The current clocks are designed so that the motor spring will reach an equilibrium with the mainspring, so the mainspring will never be completely wound tight. I imagine they put the brace in there because the early Reuter Atmos could be wound by hand and the mainspring damaged.

 

[TQ60]

It provides a strain relief.

Imagine it is fully wound.

The spring would be pulled towards the center of the circle as the spring now is wrapped around the arbor.

It would get folded where it attaches.

The brace keeps the spring straight where it attaches and acts as a "doubler" to provide support for the spring to change directions and properly wrap on the center.

 

[ALR guy]

Great explanations. Did a bit of modeling before getting TQ60's words.