Armin Strom Gravity Equal Force

A perfect example of Armin Strom’s innovation and expertise in fine mechanical watchmaking, the new Gravity Equal Force watch takes the traditional mainspring barrel and turns it on its head by adding a stop-work declutch mechanism combined with automatic winding to create consistent power delivery to the balance. With a bold redesign of the movement, dial and case, Gravity Equal Force marks the launch of the new System 78 Collection, highlighting innovative watchmaking at a competitive price.

The inspiration behind Gravity Equal Force was a desire to transmit 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.

Not content with one innovation, Armin Strom found insight in a pocket watch in need of repair from a U.S. collector, which contained a motor barrel design showing clear advantages over the standard going barrel. Inspired, the watchmakers designed a barrel operating in the reverse of a traditional mainspring barrel by driving the going train via the barrel arbor and winding the barrel housing, which both improves functionality and reduces wear.

This state-of-the-art design creates a stable, low-friction axis of rotation for the mainspring to deliver power from the barrel arbor, supported by precision jewel bearings. Though using only a portion of the mainspring by preventing it from completely unwinding, Armin Strom still achieved a power reserve of 72 hours. Wound by a unidirectionally winding microrotor visible from the dial, the mainspring bears a power reserve indicator on the barrel cover for reference.

With numerous small improvements to the going train and winding mechanism, the new Caliber ASB19 demonstrates Armin Strom’s commitment to continually questioning established theory and using in-house R&D to advance horological technology.

The new Gravity Equal Force also differs from previous models with a new off-center dial and slimmer case with a smaller diameter. The highlight of the watch is now the triplet of bridges echoing the pocket watch inspiration behind the ASB19.

The 41-millimeter case, a first for Armin Strom, should appeal to the more classically-inclined collector. The contemporary dimensions maintain the essence of Armin Strom DNA while shaping a new aesthetic that showcases a reduction to the essential. Moving to an off-center dial, the Gravity Equal Force is more legible to maximize the user experience for discerning collectors.

The Armin Strom Gravity Equal Force is the first model of the new System 78 Collection. It features a stainless steel case and is priced at CHF 16,900.

Gravity Equal Force inspiration and development

Gravity Equal Force represents a drive to constantly improve Armin Strom watches with every model. As a creative watch brand focused on innovation, Armin Strom’s watchmakers and movement engineers routinely research and explore concepts across the horological landscape in search of ways to rethink theory and practice.

The Gravity Equal Force development began with a desire to deliver equal force to the regulating system. The result was a stop-works declutch mechanism incorporated into the barrel housing ensuring consistent power delivery to the balance and escapement.

Utilizing 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 off 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 microrotor 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. Sitting atop the barrel cover, the power reserve location will change as the watch is wound, providing some playful variation in the dial display.

The new stop-works declutch mechanism coincides with a complete reassessment of the mainspring barrel construction. When a U.S. client brought a vintage pocket watch to Armin Strom for repair, it created an opportunity to explore techniques that were common in earlier watches and update them for use in a modern movement.

Upon inspection it was discovered that it bore a motor barrel whose barrel and winding mechanism are constructed opposite that of the standard going barrel. The standard design sees a central arbor often supported by jewel bearings rotating inside the barrel to wind the mainspring. Once fully wound, the arbor remains fixed while the mainspring pushes the barrel housing and so driving the going train.

A typical mainspring barrel doesn’t rotate in a precision jewel bearing but around the arbor, which means higher friction and less precise rotation. The Armin Strom motor barrel design reversed this so that the barrel housing stays locked after winding, allowing the well supported and more precise arbor to rotate and drive the going train.

This simple change goes against at least a century of tradition, yet, when assessed objectively, it is clear that it is a demonstrably better system as it is more precise and stable during operation of the movement. Armin Strom’s watchmakers built on this idea to create an entirely new watch that launches a brand-new collection.

The development of Caliber ASB19 sees continued improvement throughout all the components thanks to the technological advancement of the previous centuries. A new layout combined with improved geometry for the gear teeth and adjustments provides smoother operation and more robust functionality.

Armin Strom’s focus on innovation and development was kickstarted during the development of its ground breaking Resonance Clutch Spring and has led to the watchmakers rethinking everything in an attempt to innovate where others stagnate. This isn’t limited to mechanics alone; the entirety of Armin Strom’s design aesthetic is evolving to build a new core moving forward.

The previous open-worked display has been replaced by a dial offset from the center, providing a clear indication for the time to avoid any confusion. Retained are the visible barrel and microrotor, though now supported by clean geometric bridges harkening to pocket watches of the past. The entire presentation has the goal of reducing details to the essential for a cohesive package.

The previous case design has been trimmed down to create the first 41-millimeter case for Armin Strom. The iconic lip at 6o’clock, which can be traced back to Mr. Armin Strom himself, is still present, though in a much more streamlined form. Armin Strom has taken the opportunity to improve finishing on every component throughout the movement, creating a new standard for Armin Strom calibers.

The entire philosophy of development at Armin Strom is reorganizing to focus on updating the aesthetic design to signify a new chapter for the brand. The intention is to take every opportunity to rethink watchmaking theory, improve each new watch, and take Armin Strom’s level of finishing ever higher.

The System 78 Collection

The Gravity Equal Force signals a new direction for the brand, launching the System 78 collection to replace the Single Barrel Collection. The collection is intended to be the entry point for Armin Strom, an haute horlogerie collection at a reasonable price point with impeccable finishing and constant invention. The name displays what the brand hopes to create, a System of fine watchmaking available to all who desire it. Every piece will feature an 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. Thus the System 78 collection is born.

Technical specifications

Model: Gravity Equal Force
Ref. ST19-GEF.90.AL.M.35

Indications
Hours, minutes, seconds, power reserve indicator

Movement
Armin Strom manufacture Caliber ASB19
Automatic winding with microrotor, Geneva-drive equal force barrel, offset display with subdial seconds
Regulating system: Balance wheel with 4 regulating screws
Power reserve: Geneva stop-work limited to 72 hours
Dimensions: 35.52 mm x 11.67 mm
Frequency: 3,5 Hz (25,200 vph)
Finishing: Hand-finishing to the highest quality level
Jewels: 28
Number of components: 202

Case
Stainless steel
Sapphire crystal and case back with anti-reflective treatment
Diameter: 41 mm
Height: 12,65mm
Water resistance: 3ATM

Dial
Offset with sub-dial
Hands: Manufactured by Armin Strom – stainless steel with hand finishing

Straps
Delivered with a genuine black alligator leather strap and stainless steel ardillon buckle
A stainless steel double-folding clasp is an option.

Price
CHF 16,900