mechanical watch [2]

Set of geared wheels that reduce the force transmitted by a spiral spring to cause the watch’s hands to rotate.

jewel

Very hard stone (formerly a ruby, today a rock crystal) that resists wear; the rotation axle of a wheel rests on it.

escape wheel

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

Flat spiral spring that causes the wheels of a watch to move over a certain period of time.

center wheel

Wheel that is connected to the hands and causes them to rotate on the dial.

ratchet wheel

Toothed wheel having only one direction of rotation; it is kept in place by the click.

click

Small lever that is engaged between the ratchet-wheel teeth and prevents it from rotating counter to its normal direction.

winder

Part that rewinds the mechanism, consisting of a series of wheels.

third wheel

Wheel that receives energy from the fourth wheel and drives the center wheel.

fourth wheel

Wheel that transmits energy to the third wheel.