Piaget automatic calibre

Automatic / self winding

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The 1270P caliber – one of the latest, thinnest and a very beautiful automatic movement
( )

In the beginnings, when I was young and inexperienced, I believed that automatic watches are a new thing, coming from the modern ages… I was terribly wrong! But then I started to discover watches older than me and much older than that with self-winding. The second surprise was the micro-rotor (explained later) – that I first discovered in Piaget some years ago and I thought to myself that is a good idea, at last, the modern miniaturization can find a solution for the big wing that covers almost half of the mechanism. And I was so wrong again, even worse than the first time. So I decided to find out a little bit more about it.

The automatic (self-winding) calibre permits the wounding of the mainspring through the motion of the wearer. This system makes possible that on a normal wear to skip the need of the manual winding and have enough energy in the spring for a continuous operation of the movement even if the watch is not used during the night or for a longer time (for those with great power reserve).

The history of the automatic / self-winding mechanism for watches is rich and since the first/true inventor is somehow hard to be recognized and the literature is vast I will give at the end some links and recommendations.

Perrelet pocket watch self-winding

At the beginning of 1777, Abraham-Louis Perrelet used an oscillating weight mounted in a pocket watch (Montre a Secousses), with an up / down movement permitting a full winding in 15 minutes of walking. He later used this principle to invent the pedometer. 

In the same period, Hubert Sarton presented another series of drawing based on the principle of a rotor, that seemed to be an improved version of Perrelet’s design.

Abraham-Louis Breguet improved Perrelet’s design and used it in his pocket watches.

Breguet Perpetuelle found at the Breguet Museum Paris


Breguet Perpetuelle improved design

In 1922 Leroy (L. Leroy and Cie) created the first automatic wristwatch for Sir David Salomons. Unfortunately, I didn‘t find very much information about it.

Leroy Automatic 1922 – “Marquise”

In 1923 John Harwood patented an oscillating winding weight which contained at the ends spring-loaded buffers, the system being closer to what we know today (rotor look alike). This system was known as ‘bumper’ watches and it only wounded at a clockwise movement.

Harwood pivoting weight 

This design was used by several companies and is usually met in the 40’s and 50′ automatic movements of Omega, Eterna, Movado, Jaeger-LeCoultre, Fortis etc

Omega Bumper


Movado Bumper


Heuer Bumper Triple Date Calendar


Jaeger-LeCoultre Memovox Bumper

In 1930 Rolex brought to the world a weight wing capable to rotate 360deg – Rolex Auto Rotor used for The Oyster Perpetual. Their patent was valid till 1948 and since then was used in many forms by all brands.
Rolex Auto Rotor Oyster Perpetual 
In 1942 Felsa – a raw movement manufacturer (Ebauche movement) created the first bidirectional working rotor featuring a switcher on the gear basis – calibre Felsa 692 – The Bidynator.
Felsa 692 – The Bidynator
In 1948 Eterna improved the 360deg rotor design using ball bearings instead of jewel bearing, providing more reliable and robust support for the weight wing.
Today, both unidirectional (Valjoux 7750) and bidirectional (Rolex 3135) wounding are met.

In 1955 Universal Geneve integrated into the Calibre 215 the first of-centric planetary rotor, a micro-rotor. The brain behind the patent n.329805 was Charles Gérald Genta.

Universal Geneve Caliber 215 with the micro-rotor


The first automatic alarm clock was the 1956 Jaeger-LeCoultre Memovox.
 Jaeger-LeCoultre Memovox automatic (bumper) Calibre 815
The first automatic chronograph? At the end of the 60’s several brands fought to bring the automatic in the chronograph wristwatches. The list contains Zenith El Primero, Heuer-Leonidas and Dubois Depraz for Hamilton and Breitling, Seiko.
Calibre El Primero 3019 PHC, 1969 – 5Hz beat – the rotor is missing from this picture
In 1998 Fortis started producing the first alarm chronograph automatic: – the F2001-5 developed by Paul Gerber (Patent Nr. 689 470) for aeronautic usage.

Now, automatic movements are required more by the regular users and pushed the development even more by creating the Automatic Quartz – a hybrid – a quartz movement powered by a micro electric generator actuated by a classical rotor mechanism and a capacitor as an energy store. This solution combines the beauty of the mechanical rotor (many times visible through the crystal back) with the precision of the quartz resonator without the environmental issues of batteries. This type of movement is named Auto-quartz (name used including by ETA).

One of the first manufacturers was Seiko (Kinetic movement).

Seiko Kinetic 5M42 calibre

Another example of auto quartz is the ETA 205.111 found in Omega Seamaster Omatic:
Omega Seamaster Caliber 1400 (Auto-quartz ETA205.111)

The automatic movements are in any version a nice to have featured in any watch especially when this is visible through the back or even from the front (aesthetic reasons).

 Perrelet double rotor caliber P181

Some are considering this a complication, others don’t, so I guess it is a matter of taste. For me this is the most important feature of a watch.

Piaget caliber 1200S platinum 2.4mm thickness – the world smallest
There are more than sure a lot of other information worth mentioning but for a start I will be happy if I will remember all this information over time. At the end I put some links that I’ve read (others than the pictures sources) and if someone considers that something is missing or wrong, just let me know.

“Armbanduhren mit Komplikationen” – Constantin Parvulesco


  1. Hi,
    Researching automatic winding I came across your website. The "best kept secret" is so because the rotors are actually the cams for equation of time/long term calendars. Look closely & you'll see the roller followers.
    Search for George Daniels equation complication for clarity.

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