How does an automatic mechanism work?

All self-winding watches work on the principle of converting arm motion (kinetic energy) into the winding of the mainspring (potential energy).Usually, this is performed by a half-disc of metal weighted at the edge called a rotor, which spins when the wearer's arm is accelerated unpredictably(that is, when moved normally in the course of everyday life).This rotary motion is then geared down to wind the central arbor of the mainspring.
All automatic watches have an overwind protection mechanism of one sort or another, to prevent breaking the mainspring once fully wound,such as Rolex replica,Porsche Design replica,Richard Mille replica,Zenith replica and Hublot replica.In a typical system, the mainspring, which is wound at the central arbor of the barrel, is not rigidly attached to the outside of the barrel.Instead, there are a series of detents along the outer edge of the barrel that allow a stiffly constructed mainspring part called the bridle to slide along when an attempt to overwind is made.On some watches, a faint click can be heard when this happens,such as Ferrari replica watches,Breitling replica,U-Boat replica,Bell&Ross replica,Patek Philippe replica and Omega replicas.On others, it cannot be heard.It should be noted that this overwind protection is critical to avoid damage to the watch, and is reported to be one of the more tricky things to get right during a watch service because of the special lubricant needed to ensure proper operation.
The Horologium contains several articles about different types of automatic winding systems, including a vintage JLC/Vacheron automatic, a modern production JLC as in used in the International Watch Company (IWC) Portugieser Automatic (scroll to the bottom of the article), a modern ETA/Eterna system as used in an $85 Swatch Automatic, and an innovative bi-directional system from the IWC Caliber 8541 (now used in the new IWC Cal. 5000).