mechanical watch [2]![click to hear](/images/speaker.jpg)
Set of geared wheels that reduce the force transmitted by a spiral spring to cause the watch’s hands to rotate.
jewel ![click to hear](/images/speaker.jpg)
Very hard stone (formerly a ruby, today a rock crystal) that resists wear; the rotation axle of a wheel rests on it.
escape wheel ![click to hear](/images/speaker.jpg)
Last wheel of the gear train with special teeth that causes the watch to operate regularly and continuously; it controls the movement of the other wheels.
hairspring ![click to hear](/images/speaker.jpg)
Flat spiral spring that causes the wheels of a watch to move over a certain period of time.
center wheel ![click to hear](/images/speaker.jpg)
Wheel that is connected to the hands and causes them to rotate on the dial.
ratchet wheel ![click to hear](/images/speaker.jpg)
Toothed wheel having only one direction of rotation; it is kept in place by the click.
click ![click to hear](/images/speaker.jpg)
Small lever that is engaged between the ratchet-wheel teeth and prevents it from rotating counter to its normal direction.
winder ![click to hear](/images/speaker.jpg)
Part that rewinds the mechanism, consisting of a series of wheels.
third wheel ![click to hear](/images/speaker.jpg)
Wheel that receives energy from the fourth wheel and drives the center wheel.
fourth wheel ![click to hear](/images/speaker.jpg)
Wheel that transmits energy to the third wheel.