Moritz Grossmann BENU Power Reserve

This year, Glashütte based Moritz Grossmann Manufacture unveils a new model – BENU Power  Reserve, a continuation of their BENU line introduced in 2011. BENU, the first manual winding wrist watch model from the young German manufacture which inspired from the Grossmann Heritage already incorporated genuine innovations. Now, in 2013, the BENU Power Reserve stands out with four additional breakthroughs that refine user friendliness and functional reliability.

  • The novel power reserve indicator emphasizes the perfection of the second generation BENU
  • The newly designed oscillator – the Grossmann balance – is crafted in house in its entirety.
  • The Grossmann winder with pusher features an enhanced hand-setting mechanism
  • The re-modified Glashütte stop work supports the flexible arrangement of the parts.

The narrow bezel of the slender, three part case puts the focus on the face this thin timepiece. With its crisply defined minute scale, readily legible Arabic numerals, and the graceful, sharp tipped handcrafted in-house, the BENU evokes the aesthetic clarity of a 19th century precision measuring instrument from Glashütte. The red/white bar shaped Power reserve indicator and the separate pusher adjacent to the crown are visible identifiers of the second generation.

The BENU power reserve is being launched in four versions: rose gold, white gold, and platinum with Argenté or grey dials. Special emphasis has been placed on the making of the hands. To achieve the best possible contrast against the grey dial, the shiny hands are crafted from stainless steel according to a proprietary process.

Pockets in the hands filled with a bright HyCeram compound. This material is dyed for UV stability and forms a permanent bond with the surrounding metal. The colored filling can be ground flush with the hands and polished. As a result, the svelte, manually crafted Grossmann hands are especially brilliant and deliver precise readings of the time.

The Caliber 100.2 movement of the BENU Power reserve is the familiar classic BENU style pillar movement with a 2/3 plate, cantilevered balance cock, and the typical Grossmann micrometer screw.

The BENU power reserve unites the traditional characteristics of Grossmann style horological prowess with modern watchmaking elements and the hall marks of the new brands:-

  • Pillar movement with 2/3 plate and frame pillars in untreated German silver
  • Hand engraved 2/3 plate, balance cock, and the escape wheel cock
  • Wide horizontal Glashütte ribbing on the 2/3 plate
  • Adjustment with Grossmann micrometer screw on a cantilevered balance cock
  • Separately removable clutch winder
  • White sapphire jewels in raised gold chatons with brown violet pan head screws
  • 3 band snailing on the ratchet wheel

As was the case in Glashütte observation watches, the BENU features a compactly designed crown wheel differential train beneath the ratchet wheel. In this train, the rotary motion that occurs when the movement is wound or the mainspring unwinds is transferred to a carrier arbor with a planetary wheel. The display segment, one part white, the other red, is positioned above the hour wheel. A spring presses the hour wheel against its collar and the display segment against the dial; this stabilizes both parts without affecting their rotation.

The specially designed bearing of the segment allows the power reserve indicator to progress without affecting the movement, winder, or hour wheel. An aperture in the dial beaneath the logo makes the display segment appears as a white/red bar. When the main spring is fully wound, the bar is white. The red portion gradually appears as the spring winds down.

The newly designed oscillator had its debut in the 100.1 movement. Optimized for artisanal manufacturing techniques, the ingenious design of the Grossmann balance improves the adjustability of inertia and achieves high kinetic energy combined with minimized air resistance and the smallest possible mass. The number of screws in the balance wheel rim was minimized, and the bores in the rim are equidistant. This makes its possible to vary the moment of inertia by inserting mass screws with different head lengths in the bores.

The smooth cylindrical balance staff is integrated in the hub and can easily be replaced if necessary. The Grossmann balance interacts with a Nivarox 1 balance spring which is overcoiled with a quarter arc on the inside and secured to the slotted roller with a brass pin.

The watchmakers at Grossmann addressed the requirements imposed on a manually wound watch by focusing on improved convenience and greater functional reliability. The Grossman winder with pusher features a refined hand setting mechanism that eliminates two possible error sources: the ingress of particles in the case while the hands are being set and the unintentional alteration of the hand while the crown is being pushed home again. When the user briefly pulls the winding crown out, this mechanism switches to the hand setting mode and stops the movement. The crown immediately returns to its home position but can be turned to precisely set the hands. Afterwards, the movement is restarted with the pusher adjacent to the winding crown without altering the positions of the hands. At the same time, this switches the mechanism back to the winding mode.

A modified Glashütte stop-work secures the tension of the mainspring. After winding, it allows the ratchet wheel to reverse somewhat and slightly relax the mainspring.

Starting with the calibre 100.1 movement, Grossmann’s watchmakers introduced an optimized, space saving variation of this recoil. The stop click sits on a lever that pivots above the centre of the mainspring barrel and accommodates the backlash stroke.

The following BENU Power reserve models are available

  • BENU Power reserve rose gold, Ref 001.C211-11-1 Argenté dial, Price: EUR 26,800
  • BENU Power reserve white gold, Ref 001.C221-11-1 Argenté dial, Price: EUR 27,800
  • BENU Power reserve white gold, Ref 001.C221-13-1 grey dial, Price: EUR 27,800
  • BENU Power reserve Platinum, Ref 001.C231-13-1 Argenté dial, Price: EUR 36,800

Technical details
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
Movement dimensions: Diameter: 36.4 mm, height: 5.4 mm
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

Special features

Grossmann balance; lateral pusher for disabling the handsetting 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 handsetting

Operating elements

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

Hours and minutes, subsidiary seconds with stop seconds, Grossmann winder with pusher, power-reserve indicator

Case, dial & strap
Three-part, precious metal
Case dimensions: Diameter: 41.0 mm, height: 11.65 mm
Dial:  Solid silver, with Arabic numerals
Hands: Hand-crafted, steel or stainless steel
Crystal/display back: Sapphire crystal, antireflection-coated on one side
Strap: Hand-stitched alligator strap with butterfly clasp in precious metal

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