Moritz Grossmann BENU Tourbillon Brown, Unique Piece, 10th Anniversary Collection

Christine Hutter established Grossmann Uhren in Glashütte – a town in the German state of Saxony – in November 2008. The manufactory produces precise timepieces to the very highest standards of skill with classic yet contemporary design. The BENU Tourbillon Brown boasts a number of unique features which demonstrate the best of Moritz Grossmann’s famed craftsmanship.

As part of Mortiz Grossmann’s 10th anniversary collection, this one-off piece has a dark brown dial which blends seamlessly with the strap. At the heart of the BENU Tourbillon Brown is an optimised calibre 103.0 movement, hallmarked by a flying three minute tourbillon with a screw-secured driving wheel and a Vshaped cage, an asymmetric-arm lever escapement with a counterweight and lever banking pin, and the characteristic Grossmann balance with a suspended balance spring and regulation via poising screws in the balance-wheel rim.

The dark, chocolate brown dial exudes precision reminiscent of an aircraft cockpit. Two subsidiary dials display the seconds and hours directly and exactly. In the lower quarter, where the 6 o’clock mark usually appears, the tourbillon aperture impinges on the time span from 25 to 35 minutes. During this ten-minute segment, an extension of the minute hand sweeps a scale opposite, allowing the time to be read precisely in an original, aesthetically appealing fashion.

The timepiece uses Grossmann’s manual winding with a pusher. When the crown is pulled out to set the watch, it immediately returns to its home position. The movement is stopped and the crown can now be turned to set the hands instead of winding the watch. The stop mechanism is triggered at the same time. The stop-seconds function can operate at any time thanks to an elaborate cage design with just two triangular posts.

To halt the balance, the stop device moves past the cage’s triangular frame posts when the post is aligned with the stop lever. It does this with the aid of an elastic brush made from human hair, which provides a gentle solution for the stop mechanism which also offers long-term reliability. Pressing the pusher restarts the watch.

The BENU Tourbillon Brown is offered in the limitation 1 / 1.

Technical details

Movement
Manufacture calibre 103.0, manually wound, adjusted in five positions
Diameter: 38.4 mm, height: 7.1 mm
No. of parts: 245 (wheel train 186, cage 59)
No. of jewels: 30, 4 of which in screwed gold chatons (wheel train 17, cage 13)
Escapement: Lever escapement
Oscillator: Grossmann three-minute tourbillon with stop seconds; shock absorbed Grossmann balance with 4 inertia and 2 poising screws, suspended Nivarox 1 balance spring with No. 80 terminal curve, Gustav Gerstenberger geometry
Cage diameter: 16.0 mm
Cage speed: 1 revolution in three minutes, anti-clockwise when viewed from dial side
Balance: Diameter: 14.2 mm, Frequency: 18,000 semi-oscillations per hour
Power reserve: 72 hours when fully wound

Functions
Sweep-minutes, off-center hours and seconds, subsidiary seconds with stop seconds, Grossmann manual winder with pusher

Operating elements
Crown in 750/000 gold to wind the watch and set the time, pusher in 750/000 gold to start the movement

Case
Three-part, in 750/000 Gold
Diameter: 44.5 mm, height: 13.8 mm
Crystal/display back: Sapphire crystal, antireflective coating on one side

Dial
Solid silver, three-part, brown with Arabic numerals
Hands: Manually crafted, steel annealed to a brown-violet hue or stainless steel polished

Strap
Hand-stitched alligator strap with butterfly clasp in 750/000 Gold

Special features
Flying three-minute tourbillon with screw-secured driving wheel and V-shaped balance bridge (design patent pending); Sweep minutes, off-center hours and seconds with stop seconds; replacement of the missing minute scale segment from 25 to 35 minutes with a separate scale swept by the extension of the minute hand on the opposite side (patent pending); Stop seconds at the balance wheel rim with a pivoting fine-hair brush (patent pending); asymmetric-arm lever escapement with counterweight and lever banking pin; Grossmann balance with suspended balance spring, adjustable with poising screws in the rim; newly developed mainspring barrel jewel bearing; brake ring on the fourth-wheel arbor made of very hard, oily guaiacum; ARCAP train wheels; Grossmann winder with pusher to deactivate the hand setting mode and start the movement; modified Glashütte stopwork with backlash; pillar movement with 2/3 plate and frame pillars in untreated German silver; hand-engraved 2/3 plate and tourbillon cock; broad horizontal Glashütte ribbing; 3-band snailing on the ratchet wheel; raised gold chatons with pan-head screws; white sapphire bearing jewels; separately removable clutch winding mechanism

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