The mainspring is a small powerhouse: it stores the winding energy and transfers it evenly to the gear train. To be able to do this optimally, it must be unbreakable, resistant to kinking and bending, anti-magnetic, corrosion-resistant, and fatigue-proof. At the same time, it should be as small as possible so as not to take up too much space in the movement, but as large as possible in order to store a particularly large amount of force and ensure a long power reserve. The mainsprings for NOMOS watches are made especially for NOMOS Glashütte.
In our manual winding movements, a small plate is welded onto the end of the mainspring to anchor it in the barrel. This ensures that the mainspring cannot slip. When winding a hand-wound watch, therefore, a clear resistance can be felt when the mainspring is stretched to its maximum. The situation is different with automatic watches. Since their rotor wants to wind the spring further with each movement, there should be no resistance here when the watch is fully wound. On the contrary, the mainspring in an automatic watch needs a slip fence at the end that allows it to slip through in a controlled manner. It feels like an automatic watch can be wound by hand indefinitely. But regular wearing is also enough.