Monochrome Watches
An online magazine dedicated to fine watches

Armin Strom Gravity Equal Force System 78 (Hands-On)

Re-engineering the barrel to deliver stable power.

| By Xavier Markl | 5 min read |
Armin Strom Gravity Equal Force System 78

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.

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Armin Strom Gravity Equal Force System 78

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.

Armin Strom Gravity Equal Force System 78

Motor barrel

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.

Armin Strom Gravity Equal Force System 78

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.

Armin Strom Gravity Equal Force System 78

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.

Armin Strom Gravity Equal Force System 78

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.

Armin Strom Gravity Equal Force System 78

Armin Strom Gravity Equal Force System 78

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.

Armin Strom Gravity Equal Force System 78

The Armin Strom Gravity Equal Force retails for CHF 16,900 in steel. For more information, please visit

18 responses

  1. You’ve got to laugh at the billions of Francs being spent to increase precision but NOWHERE do you see any actual numbers proving the benefit of X,Y & Z calibre. Talk about missing the point! Can you imagine this being acceptable in ANY other engineering situation?
    “Um, yes sir, this new BMW is much more powerful, fuel-efficient and torquey. What’s that? By how much? Oh we can’t possibly tell you sir. That will be £87,000 please…..Hello? Where are you going?”

  2. Well, to be fair it is not about being more powerful or fuel-efficient. The correct analogy would be: imagine that cars would tend to malfunction as soon as their tank is 3/4 empty and you get a car that never uses that uncomfortable zone. I find it cool to have an automatic movement with a stopwork. On average, it shall just run more precise than the same movement with no stopwork. But I would not mind getting precisions about the motor barrel benefits. I assume it is quite hard to measure…

  3. And all this still gets us nowhere near a 50 EUR Casio in any terms relevant to indicating time…;-)

  4. Just to take an alternative, more simplistic view on this – although it’s by no means a cheap watch, it’s a bit more down to earth for a technically-accomplished independent like Armin Strom, considering the quality. I’d like to see this with a full-size dial, even though I know that’s not necessarily within their design code. They make great dials.

  5. Oh they’ve made an effort! Everyone is making the effort. But no-one will put their mouth where their money has gone. It’s all irrelevant.

  6. Just another guy on the Web
    You are so bloody negative. As to accuracy get yourself Citizen Eco-Drive Caliber 0100 with +/- 1 Second Per Year Precision and forget all about fine mechanical watchmaking. Your remarks are irrelevant at best.

  7. Yeah, people don’t like mechanical Watch because of their superior accuracy. In fact most of us don’t even need a watch at all considering we carry a mobile phone.
    The interesting thing is the exercise in mechanical watchmaking excellence, the intricacy of the complications, the beauty of the finishes etc. And we can all tolerate a few seconds off per day in exchange for the above.
    Having said this, why not show some stats or comparisons to substantiate a claim? It’s a matter of cementing the credibility of this watch beyond its fine watchmaking appeal.

  8. So Stanislaw, you are saying that “Fine Watchmaking” is nothing to do with telling the time properly? That people who wonder what practical difference these innovations make should just shut up?
    How does that make any sense?
    Increased accuracy is the reason given by every manufacturer for every innovation but they almost never tell you by how much.
    If you think that accuracy is irrelevant to watch-making you have rather missed the point. That is not “fine watch-making”. That is “jewellery”

  9. Hey, let me summerise all that you are all saying.

    Leo, if we didn’t like mechanical watches, we wouldn’t be reading this website.

    Of course all these watches presented here are irrelevant in terms of practical watchmaking nowadays. But we still love them, despite their inferior accuracy, or rather because of it, since it originates in the nature of their mechanics, rather than electronics of Casios and iPhones.

    However, accuracy is The Point of watchmaking (even if it doesn’t practically matter). So first the efforts to increase accuracy should be The Goal of watchmakers, and that’s what’s being done here, we understand. But making claims mine is better without supporting it with any sort of proof, is…. Well, childish. On the other hand, when hi-end bicycle manufacturers release new bikes every couple of years, they always say this iteration is by 7% more aerodynamic, 5% more comfortable, 8.2% stiffer, 3.7% lighter. They prove all this, even though the bike from two years ago was alreafy the best. And even though these numbers don’t have much practical impact (except for the pros, but there are so many factors that affect their performance that the theoretical 3.5% increase in the speed of the bike is pretty much of no importance.

    Inaccurate watch is jewellery, well put. I said the same here once when M compared a Grand Seiko to a Cartier: the Cartier could be very well worn for a dinner party even if it didn’t work at all, and it would be more than fine;-)

    Lastly, the prices of these things are astronomical. And I am not only saying this only about the 1M Richard Milles or 700K/70K Pateks but also about 17K AS. Of course hey are not really worth as much as a very decent car. But rich people are prepared to pay for all the other stuff that goes into them, which have nothing to do with actual time telling itself (mostly for self-indulgence, showing everyone around how much better they are than the crowd;-)

  10. On her another hand, is the few seconds a day accuracy important in practical terms? Those who can afford these watches have probably quite a few more in their bedside table drawers. And I doubt they wear all of them every two days to keep the power reserve on green. Or maybe they do. So they have to wind them anyway. And really, being late for a meeting by 15 seconds hasn’t gotten anyone fired yet. It’s all just the watchmakers wet dreams coming to life and being paid for unnecessarily.


  11. I think a company like this who make unconventional watches appeals to a niche market so they constantly have to come up with something new otherwise they will stop selling watches. The new watch just needs to be different to keep the factory running. Accuracy is another issue altogether. The watch I use the most gains about 2 seconds a day but I still feel the need to correct it every week.It does not matter but I do it , probably OCD.

  12. I appreciate the beauty the mechanical complexity and the arcane mechanical solutions to almost nonsensical problems. It interests me and that’s enough reason to read and observe these gentleman’s accomplishments. I would love to own one of these beauties but price prohibits. I will just have admire my AnOrdain.

  13. Just another guy on the web
    Of course accuracy has a lot to do with fine watchmaking. That´s exactly the point, how to make highly accurate and reliable mechanical watch. It is in a way an art per se. As I pointed out, a million dollar mechanical watch will not be as precise as quartz watch. Of course high end quartz watches command high price. NASA electronic are not consumer stuff. As to accuracy let me quote – In 1985 Junghans produced the first radio-controlled table clock in series. It is accurate to a single second in a million years. So what`s the point. Simply mechanical watches are separate breed that exhibit human invention in making timepieces with different approaches. Are some jewellery?, Well to classic car entusiast Buggatti or old Ferrari car engine is a jewell as well as a high achievement of what is possible to do with some crude chunks of different metals.

  14. There are many user-reports of reasonably common mechanical watches returning high accuracy: +1s/day is by no means unheard-of for Omega, GS and Rolex owners. So we should femand more from a super-specialist pieces from Armin Storm, no?

  15. @Just another guy on the web – in terms of demanding accuracy from Armin Strom – from my perspective no. Mechanical Watches (for me) are works of art and mechanics. As the owner of several vintage pieces, I don’t get them for the accuracy. I have my phone for that. I get them for the mechanics, the dial, the hands etc. For the pleasure of winding them daily etc. Never for accuracy. I have cell phones, clocks in cars, offices etc. for that. If I was a stickler for accuracy I’d just get a Seiko astron as my one watch. Just my opinion.

  16. Well we ARE allowed opinions. 🙂
    Thank you for your thoughts Richard.

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