Armin Strom - Gravity Equal Force

Armin Strom is announcing today the Gravity Equal Force, a completely new timepiece that is also the first model of a new collection called System 78 that is going to replace the Single Barrel line. The Gravity Equal Force Ref. ST19-GEF.90.AL.M.35 has a price of Swiss Francs 16,900.

Armin Strom is announcing today the Gravity Equal Force, a completely new timepiece that is also the first model of a new collection called System 78 that will replace the Single Barrel line. The 78 in the name stands for 1978, the year Serge Michel and Claude Greisler, co-founders of the modern Armin Strom, were born.

Demonstrating Armin Strom’s constant quest for innovation, the case, the dial and the movement of the new model are totally new.

In particular, the Gravity Equal Force introduces a new solution that helps transmitting equal force to the balance, thereby increasing the consistency of rate.

Building upon the classic stop-works mechanism, Armin Strom developed an ingenious stop-works declutch system that operates inside the mainspring barrel to limit the torque delivered to the balance, providing smooth power delivery. This represents the first time a stop-works declutch mechanism has been added to an automatic winding movement.

Finding inspiration in an old pocket watch in need of repair, the watchmakers of the Swiss brand also designed a barrel operating in the reverse of a traditional mainspring barrel by driving the going train via the barrel arbor. This creates a stable, low-friction axis of rotation for the mainspring, thus improving functionality and reducing wear.

Armin Strom’s Equal Force solution explained

Goal: delivering equal force to the regulating system (balance and escapement). The solution involves a stop-works declutch mechanism incorporated into the barrel housing.

Thanks to a Geneva wheel mounted to the barrel housing cover, the rotation of the mainspring barrel is limited to just 9 full turns out of a possible 12.5. This represents the central 72% of the mainspring’s potential torque curve, the flattest and most consistent portion. As the barrel housing unwinds around the arbor, a pin counts the rotations on the Geneva wheel until it reaches the locked position and prevents further unwinding.

This limit keeps the power delivery to the balance as consistent as possible and the amplitude in optimal range. Once it reaches the upper limit, the declutch mechanism guarantees the slip of the mainspring and allows the micro rotor to turn evenly when fully wound.

A small declutch lever is attached to the Geneva wheel that marks its rotation and power reserve from full to empty.

Even if it uses only a portion of the mainspring by preventing it from completely unwinding, the Armin Strom manufacture Caliber ASB19 still delivers a comfortable power reserve of 72 hours.

Wound by a unidirectionally winding micro rotor visible from the dial, the mainspring bears a power reserve indicator on the barrel cover for reference. This way, the position of the power reserve indicator will change as the watch is wound, providing a playful variation in the dial display.

Beating at the frequency of 3,5 Hz (25,200 vibrations per hour), the new movement showcases finishes of the highest quality.

In terms of aesthetics, while remaining coherent with the DNA of the brand, the new Gravity Equal Force displays a new off-center dial and slimmer case with a smaller diameter. Even the stainless steel hands are in-house manufactured, and hand-finished, by Armin Strom.

Initially available in blue or black, the hours and minutes dial is matched to a snailed small seconds sub-dial. It offers excellent readability while leaving space to the eye-catching geometries of the triplet of bridges that support the visible barrel and micro rotor. The shape of the bridges echoes the pocket watch inspiration behind the ASB19.

The stainless steel case - 41 mm in diameter (vs. 43.4 mm of the previous Single Barrel line) and 12.65 mm thick - has been streamlined in all details, including the signature lip at 6 o'clock. The finishes are outstanding, as typical of the brand. Water resistance is 3 bar (approximately 30 metres / 100 feet). At 41 mm, this is the smallest watch in the current Armin Strom collection and one that will certainly appeal the more classically-inclined collector.

Matched to a genuine black alligator leather strap with stainless steel ardillon buckle, the Gravity Equal Force Ref. ST19-GEF.90.AL.M.35 has a price of Swiss Francs 16,900. Armin Strom's effort to bring to the market of watch enthusiasts a haute horlogerie collection at a reasonable price point with impeccable finishing and true innovation fully deserves our praise. arminstrom.com