Mechanical watches have no battery, microchip, or circuitry. Watch parts are machined to near perfection at microscopic sizes and tolerances and can produce accuracy within two to three seconds per day.
A mechanical watch is driven by a mainspring which must be wound either periodically by hand or via a self-winding mechanism. Its force is transmitted through a series of gears to power the balance wheel, a weighted wheel which oscillates back and forth at a constant rate. Watch the video from Animagraffs for more info: Animagraffs
The internal mechanism of a watch, excluding the face and hands, is called the movement. All mechanical watches have these five parts:A mainspring,A gear train, called the wheel train,A balance wheel, which oscillates back and forth.An escapement mechanism, which has the dual function of keeping the balance wheel vibrating by giving it a push with each swing,An indicating dial, usually a traditional clock face with rotating hands, to display the time in human-readable form.
The mechanical watch is a mature technology, and most ordinary watch movements have the same parts and work the same way.Although the general design of mechanical watches hasn’t changed much in centuries, technology has allowed for more precise engineering and greater attention to detail.