Posted 9 years ago
Along with his chief designer Borer, the German Hans Wilsdorf developed an automatic caliber, that was introduced as the 'Oyster Perpetual' in 1931 and patented a year later.
THE ROLEX OYSTER PERPETUAL AUTOMATIC - Rotor Winding
Powered by an internal mechanism that used the movement of the wearer's arm, for the first time in a wristwatch, a 'rotor' functioned as a swinging mass winding in one direction. The complete automatic unit was located in a bowl-like frame that was screwed onto the basic movement, covering it like a hat. The screwed down back and screwed down winder made the watch water-proof. These innovations not only made watch-winding by hand unnecessary, but kept the power from the mainspring more consistent resulting in more reliable time keeping.