How its Made Machines
A mechanical watch is a watch that uses a clockwork mechanism to measure the passage of time, as opposed to quartz watches which function electronically via a small battery, or radio watches, which are quartz watches synchronized to an atomic clock via radio waves. 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. A device called an escapement releases the watch's wheels to move forward a small amount with each swing of the balance wheel, moving the watch's hands forward at a constant rate. The escapement is what makes the 'ticking' sound which is heard in an operating mechanical watch. Mechanical watches evolved in Europe in the 17th century from spring powered clocks, which appeared in the 15th century.
Mechanical watches are typically not as accurate as quartz watches, and they require periodic cleaning and calibration by a skilled watchmaker. Since the 1970s, quartz watches have taken over most of the watch market, and mechanical watches are now mostly a high-end product, purchased for their aesthetic and luxury values, for appreciation of their fine craftsmanship, or as a status symbol.
The mainspring that powers the watch, a spiral ribbon of spring steel, is inside a cylindrical barrel, with the outer end of the mainspring attached to the barrel. The force of the mainspring turns the barrel. The barrel has gear teeth around the outside that turn the center wheel once per hour — this wheel has a shaft that goes through the dial. On the dial side the cannon pinion is attached with a friction fit (allowing it to slide when setting the hands) and the minute hand is attached to the cannon pinion. The cannon pinion drives a small 12-to-1 reduction gearing called the motion work that turns the hour wheel and hand once for every 12 revolutions of the minute hand.
The duration of run, runtime or power reserve of a mechanical watch is mainly a question of what size of mainspring is used, which is, in turn, a question of how much power is needed and how much room is available. If the movement is dirty or worn, the power may not transfer from the mainspring efficiently to the escapement. Service can help restore a degraded runtime. Most mechanical watch movements have a duration of run between 36 and 72 hours. Some mechanical watch movements are able to run for a week. More details
