The new watch, which is limited to 20 pieces worldwide, is the fourth in Harry Winston’s Histoire de Tourbillon collection, which is devoted to developing modern, 21st-century evolutions of the tourbillon, a 19th-century invention originally devised to counteract the detrimental effects of gravity on watch movements.
The problem that the tourbillon was created to solve was inherent to pocketwatches, which were usually kept in waistcoat pockets and hence remained in the same vertical position. The tourbillon placed the critical regulating organs of a watch in a single, rotating cage, so that they are didn’t remain in a fixed position long enough for gravity to exert its pull over them. However, the modern wristwatch assumes numerous different positions during the day and requires, according to Harry Winston, a more complex tourbillon solution.
The movement of the Histoire de Tourbillon 4, Caliber HW4501, has a single oscillator, contained within three concentric cages, each of which rotates not only at a different speed, but at a different angle with respect to the other cages. The innermost cage, which encloses the oscillator and escapement, rotates once every 45 seconds. The intermediate cage, which encloses the first, rotates once every 75 seconds. And the third, outermost cage makes one revolution every 300 seconds. Working together, Winston says, the three cages ensure that gravity is unable to affect the oscillator.
An ordinary watch requires enormous precision to get enough power for the oscillator to beat strongly and regularly. In a tourbillon, the mainspring must produce enough power to drive not only the heart of the watch, but the tourbillon cages as well; and with triple the amount of cages, the technical challenge becomes even greater.
To deal with these issues, Harry Winston outfitted the Histoire de Tourbillon 4 with enhancements and refinements in its movement construction, including two, fast-rotating barrels to deliver more energy with lower friction; and a tourbillon that, despite its dimensions, is incredibly lightweight — only 1.57 grams. The low energy consumption that results from this system enables the watch to have a power reserve of 50 hours.
The oscillator itself — which includes the balance wheel and balance spring — must be made to the highest standard of precision in order for the triple tourbillon system to function properly. The balance is of the variable inertia type, with its effective inertia controlled by means of 18k gold timing screws in the rim. The balance spring, which must “breathe” as perfectly concentrically as possible, has been made with a Phillips curve; the outermost coil of the spring ends, in a Geneva-type stud, above the other spring coils.
The movement’s plates and bridges are made of strong, light, corrosion-resistant titanium; the mainplate and bridges are embellished with hand-applied chamfering. Arranged on multiple levels, the triple tourbillon carriages are fitted with an indicator for the running seconds reminiscent of an aircraft propeller. The “open grid” dial configuration, which shows off the movement through a multi-level arrangement of domed sapphire crystals, also echoes the look of aircraft cockpit instruments.
Harry Winston estimates that more than 3,500 hours of labor, plus 400 additional hours of testing, were required to develop the Histoire de Tourbillon 4. It takes the company’s most skilled watchmakers to assemble each 345-piece movement, which is then fitted into a 47-mm diameter polished white-gold case. Harry Winston’s proprietary Zalium, with DLC treatment, is used for the caseband, arches, and lugs, as well as for the bezel of the tourbillon.
Click below for a video of the Harry Winston Histoire de Tourbillon 4…