Stop-Work declutch mechanism and Equal Force Barrel
Handmade guilloche pattern on the black movement plate by Kari Voutilainen
Bridges are coated with dark grey ruthenium; the barrel and the micro rotor are coated with rhodium
Sapphire crystal and case back with anti-reflective treatment
Diameter: 41.00 mm
Height: 12.65 mm
Lug-to-Lug: 48.09 mm
Water-resistance: 30 m
Grey toned off-center sapphire dial with subdial
Steel with hand finishing and Super-LumiNova® filling
Delivered with a black fabric strap with light grey stitching
Width lugs/buckle: 20/18 mm
Pin buckle or Folding clasp available in stainless steel
A key innovation, exclusive to the first set of System 78 watches, is the very first implementation of a “stop-work” declutch mechanism to be deployed in combination with an automatic movement. Typically seen only in haute-horology timepieces that are orders of magnitude more expensive, a “stop work” mechanism offers the benefit of more consistent energy transmission. To fully understand the benefit of this mechanism, one must first understand why an ordinary watch will not run at a consistent rate throughout the duration of its power reserve.
The problem begins with the mainspring that inhabits every mechanical timepiece. A mainspring is a tightly coiled metal ribbon that resides inside of a watch’s barrel to deliver force to the movement. However, the force that a mainspring will deliver in an ordinary watch as it unwinds can never be delivered consistently, because the force provided will necessarily be higher when fully wound than it will be towards the end of its power reserve. To address this, Armin Strom implemented a “stop work” mechanism in the Gravity Equal Force that limits the mainspring from fully unwinding and thereby leverages only that part of the mainspring’s unwinding process which can deliver power most consistently.