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 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. Walt Arnstein has written an in-depth article about the Physics of the Automatic Watch’s Winding System. All automatic watches have an overwind protection mechanism of one sort or another, to prevent breaking the mainspring once fully wound. 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
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. 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, on others, it cannot be
