Armin Strom is a brand apart. Over the past few years, Serge Michel and Claude Greisler have set the foundations of this fully integrated manufacture. The young independent watchmaker has demonstrated its capacity to innovate, in particular with its Mirrored Force Resonance concept. Marking the launch of its new System 78 collection, the Armin Strom Gravity Equal Force is the purest expression of what the brand stands for; distinctive design, a constant desire to innovate and the wish to offer high-end watchmaking at a reasonable price. Let’s have a closer look at the new Armin Strom Gravity Equal Force.
Creating a movement that would deliver consistent power by rethinking the construction of the barrel.
The barrel is the device that stores energy in a watch movement, its energy source. It consists of a cylindrical box with a geared rim which holds and contains the mainspring. It turns on an axle or arbour. The mainspring is hooked to the drum’s inner wall at its outer end and to the arbour at its inner end.
CONSISTENT power delivery
The force delivered by the barrel is irregular. Strong torque is provided when it is fully wound, then it slowly wanes throughout the duration of the power reserve. This affects the rate of watches because balance wheels are not perfectly isochronous (isochronous means that the period of oscillation is independent of the amplitude of oscillation). Taming power has therefore been an ongoing horological quest. Watchmakers have worked on various solutions. For instance, the stackfreed, the fusée-and-chain, optimized barrels, remontoires, escapements, constant force escapements, etc. One of the solutions to this problem is to avoid the extremes, the high and low torque periods – when the spring is fully wound or close to fully unwound – using the spring’s optimum range only. This ensures consistent power delivery.
This is the idea that inspired the Armin Strom Gravity Equal Force. Armin Strom has created a special Geneva stop-work, just like some rare hand-wound movements, but specifically adapted to an automatic movement. To avoid low torque, the first turns of the barrel are therefore not used. In addition, this new ‘Declutch stop-work’ allows the mainspring to slip in the barrel (patent pending).
When you get a traditional automatic watch that has not been worn for some time, with its spring is completely unwound, moving the watch around will cause the rotor to spin. While your watch gets back to life, this would not be enough to tighten the spring sufficiently and to take advantage of the movement to its full capacity. It is therefore recommended to hand-wind (at least a few revolutions) the watch to tighten the mainspring sufficiently. With the Gravity Equal Force, as soon as the watch starts and the seconds hand moves, you know the spring delivers enough power.
All in all, the rotation of the mainspring barrel is limited to just 9 full turns out of a possible 12 and a half. The resulting power reserve is still generous at 72 hours. A cool addition, a small indicator is attached to the Geneva stop-work. It marks its rotation and the watch’s power reserve from full to empty.
The development of this sophisticated mechanism was the occasion to re-engineer the whole barrel construction, opting for a “motor barrel.” Traditionally, the barrel is wound by turning the arbour to put the spring under tension. This tension causes the barrel to turn in the opposite direction. It meshes with the first pinion of the gear train to drive the watch movement. This architecture is known as going barrel. But another solution consists in winding the mainspring by turning the drum rather than the centre arbour. The centre arbour then rotates to drive the gear train. The functions of the arbour and barrel are therefore reversed.
Originally, this solution was used in pocket watches to address the problem of damages caused by a broken mainspring. If the mainspring breaks, the destructive recoil force will not be applied to the vulnerable gear train. For Armin Strom, it was above all an opportunity to enhance the movement efficiency, taking advantage of the stable and precise arbour to drive the going train.
New in-house calibre
This development has been integrated into a brand new movement, the self-winding calibre ASB19. As often with the brand, the balance beats at an unusual rate of 3.5Hz or 25,200 vib/h. A stop-seconds mechanism makes accurate time-setting easier. 35.5mm in diameter, it is wound by a micro-rotor. The architectural construction combines an off-centred hours, minutes and seconds indication while three straight, geometric open-worked bridges are visible on the right side, holding in place some of the technical elements.
These allow you to admire the micro-rotor and innovative barrel with its stop-work and power-reserve indicator. Turning the watch over, the exhibition caseback offers an unimpeded view of the beautifully finished movement and its high-frequency oscillator.
The Armin Strom Gravity Equal Force
From a design perspective, while it remains true to the brand’s design codes, the Armin Strom Gravity Equal Force signals a new direction for the brand. The previous case design has been trimmed down, creating the first 41mm case for Armin Strom. The bezel and the lugs are thinner. The ‘lip’ at 6 o’clock is still present though in a much more streamlined form. An alligator strap secured by a pin buckle sets the final touch.
Launched to replace the Single Barrel collection, System 78 marks an important step in the development of Armin Strom. The collection is intended to be the entry point for Armin Strom, an Haute Horlogerie collection at a reasonable price. Every piece will feature innovation as well as showcasing the watchmaking philosophy of Serge Michel and Claude Greisler, co-founders of the modern Armin Strom, both born in the same year, 1978.
The Armin Strom Gravity Equal Force retails for CHF 16,900 in steel. For more information, please visit www.arminstrom.com.