German watchmaker Moritz Grossmann presents the ATUM Power Reserve, a combination of the ATUM model family with the calibre 100.2 movement. The power-reserve complication constitutes a prominent accent in the perfectly reduced overall appearance of the watch. Its crisply drawn minute scale and the delicately pointed, manually sculpted hands are reminiscent of 19th-century precision measuring instruments. At the same time, the two-colour bar-shaped display in the dial is a reminder that the ATUM Power Reserve is a modern manifestation of pure watchmaking artistry.
The calibre 100.2 movement embodies some of the manufacture’s most prominent proprietary developments such as the Grossmann balance, the modified Glashüttestopwork, and the Grossman manual winder with pusher. The power-reserve indicator is controlled via a slender crown wheel differential gearing. Inspired by Glashütte observation watches, it connects the spring barrel and the ratchet wheel with the power-reserve display.
Via a carrier arbor with a planetary wheel, it transfers the opposing rotary winding and unwinding motions to the power-reserve indicator. When the mainspring is fully wound, the bar is white. The red portion gradually appears as the spring winds down.
The ATUM Power Reserve comes in a rose gold and a white gold version, both with argenté dials.
Manufacture calibre 100.2, manually wound, adjusted in five positions
No. of parts: 227
No. of jewels: 26 jewels, 3 of which in screwed gold chatons
Escapement: Lever escapement
Oscillator: Shock-absorbed Grossmann balance with 4 inertia and 2 poising screws, Nivarox 1 balance spring with No. 80 Breguet terminal curve, Gerstenberger geometry
Balance: Diameter 14.2 mm, frequency 18,000 semi-oscillations per hour
Power reserve: 42 hours when fully wound
Movement dimensions – Diameter: 36.4 mm, height: 5.4 mm
Grossmann balance; lateral pusher for disabling the hand-setting mode and starting the movement; bar-shaped power-reserve indicator with two-coloured display segment driven by a planetary gearing system; space saving and modified Glashütte stopwork with backlash; adjustment with Grossmann micrometer screw on a cantilevered balance cock; Pillar movement with 2/3 plate and frame pillars in untreated German silver, 2/3 plate, balance cock and escape-wheel cock hand-engraved; broad horizontal Glashütte ribbing, 3-band snailing on the ratchet wheel, raised gold chatons with pan-head screws; separately removable clutch winder; stop seconds for hand-setting
Hours and minutes, subsidiary seconds with stop seconds, Grossmann winder with pusher, power-reserve indicator
Crown in 750/000 gold to wind the watch and set the time, pusher in 750/000 gold to start the movement
Three-part, precious metal
Diameter: 41.0 mm, height: 11.65 mm
Crystal/display back: Sapphire crystal, antireflection-coated on one side
Solid silver, hour markers in solid gold
Hands: Hand-crafted, steel or stainless steel
Hand-stitched alligator strap with pin buckle in precious metal
Case: 750/000 rose gold
Hands: Hand-crafted, steel annealed to a brown hue
Case: 750/000 white gold
Hands: Hand-crafted, hour and minute polished stainless steel, seconds steel annealed to a brown hue