Automatic

Definition

An automatic watch is one where the mainspring is wound by inertia and the movements of the wearer. Typically, a centrally mounted rotor spins around and, via reversers or magic lever, winds the mainspring.

Here's the rotor on my ETA 2824:

There are variations:

• Early automatics used edge-mounted weights and gear cages. [Citizen] did some of these; they were less efficient.

(Image credit: WatchUSeek, a Citizen Jet Parawater)

• Omega and others made so-called 'bumper' movements that swung through an arc and stopped by a spring.
• Micro-rotors like the Universal Geneve from the 1960s and the current Chopard/Parmigiani-Flurier 1.96.

See ETA 2824 for a typical current automatic movement.

Links

• SteveG pictorial on the Chopard movement
• SteveG pictorial on the Universal Geneve
• Wikipedia
• Ariel on UG and microrotors
• Post on bumpers and microrotors