HOW SELF-WINDING WATCHES WORK

The self-winding watch is the epitome of sustainable: renewable energy on tap (so long as you move your ass). Here's how the magic happens...
HOW SELF-WINDING WATCHES WORK
The basic concept of an automatic watch movement is quite simply explained. When the wearer moves their arm, a rotor is spurred into motion, sending kinetic energy via a series of gears to the mainspring (a spring that, when tightly coiled by winding, then gradually unwinds, powering the watch’s movement). It’s a neat example of ‘clean energy’, harnessing the wearer’s motions and turning them into power. If only every machine could be fuelled so sustainably… Most experts agree that the earliest authentic automatic movements were housed in pocket watches created by 18th-century watchmaker Abraham-Louis Perrelet of Le Locle, Switzerland. In 1777, Perrelet designed and built a self-winding mechanism for pocket watches using a pedometer-like oscillating weight, moving up and down. Many other leading watchmakers of the day, including another Abraham-Louis (the legendary Monsieur Breguet), worked on solutions for converting motion to stored energy in a watch, but their complexity made them difficult and expensive to produce, and it wasn’t until the early 20th century that automatic movements began to grow in popularity. Among the earliest commercially successful self-winding watches were those produced by English watchmaker John Harwood in the 1920s. Harwood patented a bumper rotor system, using a pivoting weight which swung in a back-and-forth motion as the wearer moved, rotating through part of a circle (roughly 180-200°), causing the mainspring to coil. This variant of self-winding mechanism enjoyed just a few decades’ popularity and was used in many early-model mid-century Omega Seamasters.
Far more common today are full-rotor systems, the oscillating weight turning 360°. These were first developed by Rolex for the pioneering Oyster Perpetual in the early 1930s. While Harwood’s ‘bumper’ movements possessed a power reserve of just 12 hours, Rolex’s innovation managed to triple that figure. (Consumers clearly favoured the convenience of a lengthier charge — Hardwood went out of business during the Great Depression, whereas Rolex, as you may well be aware, continues to thrive today.) The vast majority of contemporary automatic watches feature a full-rotor automatic movement with bidirectional winding, transferring power to the mainspring whether the rotor turns clockwise or anticlockwise. Occasionally — often in haute-horological creations — you’ll encounter micro-rotors, which help keep movement girth down by fitting snugly onto the baseplate. In another step to create thinner automatic movements, a decade ago Carl F Bucherer invented a peripherally-mounted ring-shaped system encircling the movement, which has been used by manufactures including Breguet and Bvlgari to create self-winding watches of exceptional svelteness. Of course, you need to keep your automatic watch wound for it to continue displaying correct time. That’s easily done if you only wear one watch, but if you have a collection you cycle through, chances are individual pieces will run out of power regularly — necessitating the fiddly task of resetting the time (and perhaps also day, date, moon phase, et cetera) whenever you want to return that piece to your wrist. The ideal solution is to store your watches in a winder when they’re not worn. This not only keeps them handsomely housed and accurate, but helps maintain the movement in optimum condition. Self-winding movements became omnipresent in mechanical watchmaking in large part thanks to the convenience they provide. Using a winder ensures your automatic watch delivers on that time-saving promise.