The new ExoTourbillon Rattrapante (ref. 109447), part of the Villeret 1858 collection, represents a milestone for Montblanc as it combines several horological complications: a large balance positioned outside the tourbillon’s rotating cage, a chronograph with split-second function, and a three-dimensional regulator dial in gold and grand feu enamel with double time-zone. It loudly states the ambitions of Montblanc in the high-end market of the watch industry.
Available in a limited edition of eighteen watches, the ExoTourbillon Rattrapante has a 47 mm white gold case with polished finishing and a highly domed sapphire crystal.
The screwed back includes a sapphire crystal viewing window through which it is possible admire the beautiful hand-wound movement with the two column wheels. The chronograph’s column-wheel is visible at 6 o’clock while the split-second column-wheel can be seen near the split-second button. The finishing is outstanding with manually bevelled levers and slender springs.
Invented in 1827 by the Swiss watchmaker Louis-Frédéric Perrelet, then perfected by the Austrian Joseph Thaddäus Winnerl, the rattrapante chronograph includes two second-hands positioned one above the other: one of them runs continually whenever the chronograph function is active; the other can be momentarily halted at the push of a button to measure an intervening interval. When this button is pressed again, the temporarily halted hand catches up and returns to synchrony with its companion. The French verb rattraper means “to catch up”, so Perrelet named his mechanism “rattrapante”.
The ExoTourbillon name explains one of the peculiarities of this timepiece. “Exo” means “outside” in the ancient Greek and, in fact, the rotating cage and the escapement of the tourbillon are positioned outside the movement’s plate and are located alongside the movement. Also, the large balance is installed outside the rotating cage and oscillates on a different plane. The balance is borne between two bridges, the upper of which has a looped shape that recalls the symbol of infinity. The tourbillon rotates in a two-point bearing at the foot of the axis.
Another exclusive feature of the ExoTourbillon is the speed of its rotation, which is performed in four minutes. Conventional tourbillons typically complete one rotation per minute. Slowing the speed of the rotations enhances the observer’s pleasure and requires less energy from the barrel while still producing the same compensating effect as a speedier tourbillon.
The three-dimensional structure of the dial with the circular aperture at 12 o'clock adds fascination to the timepiece. The central sweeping blued hand displays the minutes while the sub-dial at 6 o'clock displays the hours in two time zones: the current local time (skeletonised blued hand) and home time (grey hand). The button at 8 o'clock resets the local-time hand in hourly increments. Finally, the smaller sub-dial at 4 o'clock provides the night/day indication for the home time.
The chronograph’s central elapsed-seconds and split-second hands are activated using the integrated crown-button and the push-piece at 2 o’clock for the rattrapante function.
At 3 and 9 o'clock we have the continually running second-hand and the chronograph’s counter for thirty elapsed minutes.
The dial is decorated using the grand feu enamel technique which, better than any other method, preserves colours and gleams over the years.