The Imperial Tourbillon from Franck Muller is characterised by its high visibility. It is, so to speak, ‘suspended’ at the same level as the dial. In contrast to more traditional tourbillons, the Imperial tourbillon does not need to be guided by a visible bridge from the dial side. Its extreme originality lies in the fact that it is only held by a single pivot resting on a bridge inside the movement. Thanks to this technique, the person wearing this timepiece is entranced by the somersaults of a tourbillon without any form of attachment.
One issue related to tourbillons is that while they function well when the power supply is strong, as torque on the gear train diminishes and power reserve wanes, the accuracy of the tourbillon can become affected. That is because a tourbillon represents a heavier mechanism for the gear train to drive as compared to a simple escapement.
For this reason, many watchmakers have attempted to create constant-force devices to isolate the quality of power impulsing the tourbillon from the variable waxing and waning power supply contained in the mainspring. Thus, Franck Muller’s standard tourbillon utilizes a design different from the majority of commercially produced tourbillons.
In most tourbillons, the third wheel of the gear train drives the pinion of the tourbillon cage. However, as power supply diminishes and quality of power lessens, this diminishment can actually be amplified by the tourbillon. In Franck Muller tourbillons, instead of engaging the pinion of the cage using the third wheel, the watchmakers engage the exterior of the cage using an intermediate pinion.
The theory behind the superiority of driving the tourbillon from the exterior of the cage rather than from its pinion is related to leverage. Take, for instance, a merry-go-round that is at rest. If you try to turn it from the center, it is very difficult and it makes a big difference if you are strong or weak. But if you move to the outside of the merry-go-round and push it from its perimeter, the leverage allows you to turn it with very little force. Whether you feel weak or strong, you do not have to exert much energy. This is the same for the tourbillon; if you turn it from the exterior, it is not affected by reductions in torque from the mainspring, but if you turn it from the center, it is.
Franck Muller’s tourbillons are characterized by the use of a flying tourbillon design where the entire weight of the tourbillon is supported by the pinion of the cage. Thus, there is absolutely no upper bridge to obscure what is the most viewing pleasure in all of horlogerie.
Reference: 8880 T
18K rose gold
Width: 39.6 mm x Length: 55.4 mm x Heigth: 11.8 mm
Water resistant up to 30 meters
Hours and minutes, optional second on tourbillon
Winding crown in 2 positions
Mechanical Tourbillon with manual winding
Width: 25 mm x Length: 30 mm x Height : 5.30 mm
18’000 vibrations / hour
60 hours power reserve
Côtes de Genève, circular graining, hand beveling.
Sun-stamped white lacquered dial and Arabic numerals