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The Encyclopedia of Horology

Glossary · Mechanism

Automatic winding (self-winding)

A mechanism using an oscillating or rotating weight to rewind the mainspring from wrist motion.

Explanation

Early bumper systems used a semicircular weight swinging between banking pins; the modern rotor, generally credited in developed form to Rolex's 1931 Perpetual, rotates a full 360 degrees for more efficient winding.