The movement
Grossmann’s designers used the calibre 100.1 to devise the new calibre 100.11 for the CENTRAL SECOND.
To keep the second hand rotating in the centre of the dial, the force of the mainspring is transferred from the third wheel to the new central second wheel via an additional intermediate wheel in the centre of the movement.
To ensure that the overall look is harmonious and also homogeneous, all the components of the train bridge are aligned on one level. For this purpose, both the train bridge and ratchet wheel were extended in height.
The Grossmann balance
The CENTRAL SECOND breathes at a calming traditional rate of 18,000 semi-oscillations per hour. The calibre 100.11 incorporates the newly designed Grossmann balance and demonstrates that rate accuracy is not achieved solely with a higher frequency. Optimised for artisanal manufacturing techniques, the design of the balance improves the adjustability of inertia and achieves high kinetic energy combined with minimised air resistance and the smallest possible mass. The number of screws in the balance-wheel rim was minimised as well. Mass screws with different head lengths are used to incrementally vary the moment of inertia. Additionally, the rim is provided with uniformly spaced bores that allow reductions in mass or contribute to the poising of the balance. The smooth cylindrical balance staff is integrated in the hub and can easily be replaced if necessary. The Grossmann balance interacts with a Nivarox balance spring which is overcoiled with a quarter arc on the inside and secured to the slotted roller with a brass pin.
The Grossmann winder with pusher
On average, a manually wound watch is reset weekly. It was a challenge for the watchmakers at Grossmann to improve the functional reliability and convenience of this operation. When the user briefly pulls the winding crown out, this mechanism switches to the handsetting 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, the mechanism switches back to the winding mode. This ingenious handsetting mechanism eliminates two possible error sources: the ingress of particles into the case while the hands are being set and the unintentional alteration of the hand positions while the crown is being pushed home again.
ratchet wheel is finished with a delicate snailing decoration
Further evidence of the highest standards of craftsmanship can be seen in the tooth flanks of the ratchet wheel, which are liberally chamfered at the top and polished to a high gloss sheen. Furthermore, the ratchet wheel is finished with a delicate sunburst decoration.
The engravings by hand
All engravings and inscriptons on the 2/3 plate and the balance cock are always engraved by hand.
The central second wheel and intermediate wheel
In contrast to other Grossmann movements, the crown wheel on CENTRAL SECOND is covered by the train bridge. Alongside the ratchet wheel, the new magnificently adorned intermediate wheel, which is also very striking in terms of its size, and central second wheel also draw admiring eyes. The wheel legs of the intermediate wheel are hand chamfered and polished.
In line with the service concept championed by Grossmann, the central second wheel can easily be removed when required. A spring slots into a groove underneath the wheel and both hold the wheel in the desired position and also ensure smooth, even rotation of the second hand. In its fully assembled state, this spring can be adjusted at any time via a screw in the train bridge.
Tech Specs
Movement
Manufactory calibre 100.11, manual winding, regulated in five positions
Special features
Grossmann balance; hand setting override and start of movement with lateral pusher; space-saving modified Glashütte stopwork with backlash; adjustment with Grossmann micrometer screw on cantilevered balance cock; pillar movement with 2/3 plate and pillars made of untreated German silver; balance cock and escape-wheel cock hand-engraved; broad horizontal Glashütte ribbing; snailing on the ratchet wheel; separately removable clutch winder; stop seconds for hand setting; central second wheel
Functions
Hours, minutes and seconds, central seconds with stop second, Grossmann manual winder with pusher
No. of parts
198
No. of jewels
22 jewels, of which one in a pressed gold chaton
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
Operating elements
Crown for winding the watch and setting the time, pusher to start movement
Movement dimensions
Diameter: 36.4 mm, height: 5.30 mm