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It’s a silent dance that you wear on your wrist. An energy that is born from your gestures, passes from one metal to another, is regulated to the hundredth of a millimeter to display the correct time. There is nothing magical about the automatic movement — it is a mechanical art, heir to three centuries of ingenuity, made of masses, springs and rhythms. Here, without mystery, is how it actually works.
An invention born from movement
In the 18th century, Abraham-Louis Perrelet imagined an oscillation winding system for pocket watches. But it is on the wrist that the idea will flourish. In the 1920s, John Harwood filed the first patent for a self-winding wristwatch. Then, in 1931, Rolex imposed its 360° freely rotating rotor, the famous “Perpetual”, which would become the grammar of the genre. The following decades refined efficiency: Felsa invented the Bidynator (bidirectional winding) in 1942; Seiko popularized the Magic Lever in 1959, a simple and robust solution. The automatic is then ready for modern life.
A video that explains the movement of a watch
You have to love Tchaikovsky (which is my case) and add the rotor to the equation
The path of energy: from wrist to needle
1. The oscillating weight and the winding train
At the back of the movement, a half-moon mass – the rotor – pivots around its axis, often mounted on ball bearings. Wrist gestures rock her; its weight (tungsten, 18 or 22 carat gold) ensures inertia. The rotor transmits this movement to a set of wheels and pawls: the winding train. Depending on the construction, the energy is captured in one direction (unidirectional) or in both (bidirectional via “reversers” or a two-arm Magic Lever which captures the round trip). Objective: convert random gestures into effective winding.
2. The barrel and the sliding flange
This winding tightens a mainspring contained in the barrel. To avoid any destructive overtorque, the last turn of the spring has a sliding flange: it adheres to the wall of the barrel by friction and slips when the maximum tension is reached. Result: you don’t “break” an automatic by wearing it too much; excess energy dissipates as it glides elegantly.
3. The gear train, the escapement and the balance wheel
The energy leaves the barrel through a cascade of reducing wheels (the gear train) to the Swiss lever escapement. There, the movement is granulated into regular impulses, which keep the balance spring oscillating. He is the beating heart: his frequency — 21,600, 28,800 or even 36,000 vibrations/hour — defines the cadence; its amplitude, the health of the setting. The hairspring, preferably made of silicon, breathes, the balance oscillates, and each impulse releases a step, making the hands rotate at the right speed.
An art of solutions: unidirectional, bidirectional, micro-rotor
Each house chooses its school. Unidirectional limits losses and simplifies the architecture; bidirectional maximizes energy capture in the city and in the office. The Magic Lever, acclaimed for its robustness, offers remarkable efficiency with few parts. Others make finesse a manifesto: the micro-rotor, recessed flush with the plate, allows flatter, elegant movements under a sleeve. The peripheral rotor, in a ring around the perimeter, frees the view of the movement and lowers the center of gravity. In all cases, the aesthetic dialogues with the mechanics: openwork gold mass, Côtes de Genève, guilloché… the technique becomes decor.
Precision and regularity: what happens inside
A well-designed automatic movement aims for power reserve (40 to 80 hours, sometimes more) and running stability. Precision depends on the fine adjustment (racket, weights, silicon hairspring to limit magnetic sensitivity), the quality of lubrication and the amplitude. The shocks? Anti-shock systems like Incabloc or KIF protect the balance pivots. The best achieve chronometry standards (COSC, -4/+6 s/day) or their in-house variants. And because life is not a window watch, the stop-seconds for setting the atomic time and the complementary manual winding remain comfort assets.
Received ideas to forget
- “I don’t move much, my watch is going to stop.” A normal daily life is enough. If you are very sedentary, 20-30 turns of the crown in the morning stabilize the reserve.
- “You can wind an automatic too much.” The sliding flange protects: no breakage due to excessive winding.
- “A watch shaker replaces maintenance.” No. It keeps things running, not oils. Periodic review remains necessary.
- “Magnetization = end of movement.” Often reversible in one minute with a demagnetizer; the silicon hairsprings are almost insensitive to it.
- “A mechanical watch must be perfect.” Expect reasonable, stable, repeatable drift, more than absolute zero.
Use and maintenance: the practical truth
An automatic likes to be carried. One or two days of gestures punctuate its power reserve. Alternating it on a winder can help if you have calendar complications, but is not essential.
In terms of care, the golden rule is regularity: a watertightness check every year if the watch sees water; a service every 5 to 7 years depending on use, to replace oils and seals, check the wear of the axles and jewels, clean the gear train and the escapement. Avoid strong magnetic fields (speakers, case clasps, industrial gates), rinse with fresh water after the sea, and handle the screw-down crown gently. Placed on the table, vary the position at night: certain watches gain or lose differently “high dial”, “high crown”, which empirically refines the drift.
Why we love them: beyond technique
- The sensation: the slight back and forth of the rotor, an intimate nod to living mechanics.
- Beauty: a micro-rotor that opens up the view onto a mirror-polished bridge; an engraved 22-carat gold mass, weighted for greater efficiency.
- Culture: from “Perpetual” of 1931 to Magic Lever, each solution tells of an era, a workshop philosophy.
- Durability: no battery to replace; an ecosystem of replaceable and revisable parts that spans the decades.
As a second finale
An automatic movement is a happy compromise: capturing the randomness of life and converting it into measured time. A weight that turns, a spring that stretches, a pendulum that breathes — and suddenly your day takes on a rhythm. In this mechanism, there is intelligence, hand and a little poetry. Every gesture lifts you up; every second resembles you.
