Moritz Grossmann ATUM ‘Backpage’ – Rose Gold Model with Grey Dial and Platinum Model with Blue Dial

Moritz Grossmann expands its ATUM series by presenting a new model with the new caliber 107.0 that offers eye catching views of inner workings on both sides of the watch.

Until today, most of the highlights of a Moritz Grossmann calibre could only be admired on the caseback side of the watch.  The calibre 107.0 is a mirror image of calibre 100.1 but has been redesigned for reverse rotation so that the movement can sit ‘upside down’ in the case. A generous aperture in the dial then exposes characteristic movement details such as the Grossmann balance, the hand-engraved balance cock and the 3-band snailing on the ratchet wheel – all without taking the watch off the wrist.

Two versions have been produced, in rose gold with a grey dial, and in platinum with a blue dial.  In each case, the dial presents a full minute scale and an hour display from 11 to 5 o’clock to frame the glittering calibre presentation.  Gold hour markers and numerals match the case colour. The recessed small seconds ring has an extravagant bearing for the second hand featuring a gold chaton.

Calibre 107.0 is essentially a mirror image of the calibre 100.1, but with crucial new design elements. An additional wheel between the crown wheel and the ratchet wheel reverses the entire drive train with respect to the rotation of the mainspring barrel. The wheel train runs in the right direction thanks to the mirrored escapement and the mirrored oscillation system – also including the balance spring coiling direction.

The larger dimensions of the 2/3 plate necessitated design changes for the balance cock and the escape-wheel cock. The cantilevered geometry of the escape-wheel cock creates a balanced accent in the overall arrangement of the movement. The High-Artistic finish showcases attractive hand engravings, bevels, and chamfers.

To achieve the desired presence of the winding wheels on the dial side, the dial train was reconfigured. The artistically finished train wheels were arranged beneath a lavishly polished minute-wheel bridge. Since in this case, the hand-setting mechanism is located on the opposite side of the movement, the setting wheel extends all the way through the calibre. The new arrangement created space for the optimised barrel bearing and the ratchet wheel, which was also shifted to the front side.

On the new rear side of the movement, the winding and hand-setting mechanism is now openly integrated in the train bridge, so its functionality can be fully observed for the first time.The stop-seconds and stop-balance functions have been redesigned as well. In the hand-setting mechanism, the brake position is sampled at the clutch lever and, via a push rod, transferred to the brake spring, which then stops the balance. After the pusher is activated and the movement starts, the brake spring returns the push rod to its rest position.

The platinum version is limited to 18 pieces.

Technical details

References
MG-001396: 750/000 rose gold case, Charcoal dial; Hands: Manually crafted, steel, annealed to a brown hue
MG-001642: Platinum case; Blue dial; Hands: Manually crafted, annealed to a blue hue; Limited edition of 18 watches worldwide

Movement
Manufacture calibre 107.0, manually wound, adjusted in five positions
Diameter: 36.4 mm, height 5.0 mm
No. of parts: 230
No. of jewels: 24, of which 7 in screwed gold chatons
Escapement: Lever escapement
Oscillator: Shock-resistant 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/hour
Power reserve: 42 hours when fully wound

Functions
Hours, minutes, and subsidiary seconds with stop seconds, Grossmann winder with pusher

Operating elements
Crown in precious metal, for winding the watch and setting the time, pusher in precious metal for starting the movement

Special features
Shock-resistant balance with inertia and poising screws, impulse pin integrated in rim; flat balance spring; balance staff with integrated safety roller; index adjuster with Grossmann micrometer screw; plate movement with 2/3 plate on dial side, frame pillars and separately removable clutch winding mechanism; visible handsetting train on the back side of the movement; frame parts in untreated German silver; Grossmann winder with pusher and stop seconds; raised gold chatons with pan-head screws; remodified Glashütte stopwork with backlash; mainspring barrel with bilateral jewel bearings for optimised power management in the low-torque range; ARCAP train wheels; proprietary escapement with 18-tooth escape wheel; balance cock and crown wheel, intermediate winding wheel and ratchet wheel with stopwork on the modified spring barrel bearing with a gold chaton in the ratchet wheel; dial train wheels spoked and beveled, beneath polished bridge

Case, dial and strap
Case: Three-part, precious metal
Diameter: 41.0 mm, height 11.35 mm
Dial: Solid silver, baton hour markers in precious metal
Hands : Manually crafted, steel, annealed to a brown or blue hue
Crystal and display back: Sapphire crystal, antireflective coating on one side
Strap: Hand-stitched alligator strap with prong buckle in precious metal

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