Launched at the end of 2019, the Armin Strom Gravity Equal Force is the modern yet traditionally elegant fruition of the brand’s research for new solutions to deliver consistent power in mechanical watches. If its architectural movement with three parallel bridges is reminiscent of the pocket watches of yesteryear, it also packs several original solutions. Initially presented in steel, the model now comes in an elegant pink gold version.
The regulating organ of mechanical watches is not perfectly isochronous. In layman’s term, the rate (hence the precision) of your mechanical wristwatch depends on the power delivered to its balance wheel. The period of its vibrations depends upon their amplitude. This amplitude may vary across the power reserve of the watch. Notably, significantly different power is delivered just after winding and at the time when the watch has to be rewound. To improve rate regularity, watchmakers have worked on a variety of factors; among these, delivering an energy flow as consistent as possible.
This has been the focus of Armin Strom with the creation of the Gravity Equal force, the inaugural piece of its system 78 collection. Its ASB19 calibre aims to deliver consistent power by rethinking the construction of the barrel.
The barrel is the organ that stores energy in a mechanical movement. A cylindrical box with a geared rim, it contains a coiled spring. 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. The Gravity Equal Force ASB19 calibre is fitted with an innovative ‘declutch’ stopwork specifically adapted to the specificities of an automatic movement. With it, only the optimal range of the power reserve is used. To avoid low torque, the first turns of the barrel (low power reserve) are not used. In practice, only nine turns of the barrel are used out of a possible 12 and a half. The power reserve is still 72 hours. Additionally, the mainspring can slip in the barrel, which is needed for an automatic movement. Last, the barrel is a so-called motor barrel, a reverse construction to provide a stable, low-friction axis of rotation by driving the gear train by the barrel arbor. (For more details, please read our introductory article here).
Besides this novel solution, the calibre ASB19 stands out with its openworked architectural design. Next to the off-centred dial, three straight parallel bridges are fitted across the movement, harkening to pocket watches of the past. These bridges hold the micro-rotor, the gear train and the barrel that features a power reserve indicator, in place. Turning the watch over, this finely hand-finished movement is also visible via the exhibition caseback. It is housed in a 41mm case that retains the signature design codes of Armin Strom but with a more elegant, classic twist. The bezel and the lugs are thinner and the lip at 6 o’clock is more discreet. Initially presented in steel, the model is now presented in a pink gold version that confers a warm radiance and a more luxurious feel to the watch. The black dial highlights the new design of the watch with striking contrast.
The Armin Strom Gravity Equal Force is worn on a black alligator strap with a pin buckle. It retails CHF 26,900 in pink gold. For more information, please visit www.arminstrom.com.
Technical specifications – Armin Strom Gravity Equal Force Pink Gold
41mm diameter x 12.65mm height – pink gold case, brushed and polished – sapphire crystal with anti-reflective coating – water-resistant to 30m
off-centred black dial with hours, minutes, seconds – openworked hands
calibre ASB19 – automatic with micro-rotor and Geneva-drive equal force barrel – 35.52mm x 11.67mm – 25,200 vibrations per hour – 72-hour power reserve – 28 jewels – 202 components – hours, minutes, seconds, power reserve indication
alligator strap with pin buckle