I just got the request by email to publish more about the IWC Ingenieur Constant-Force Tourbillon featured in the today´s episode of The Man´s Guide to Haute Horlogerie. That´s no problem! Guys, there you go…
First of all thank you for your interest Stephan! Yes, the request came from Germany. I of course have more detailed information about that fascinating watch. I hope this addition lets you understand the mechanism better and I hope my little HD-video and the pictures do also help…
Because the mainspring in a conventional hand-wound movement is under more tension when freshly wound than when running down, the amount of power it generates varies constantly. IWC’s team of engineers, watchmakers and designers sought an answer to the problem for 10 whole years. The result of their efforts is a highly complex constant-force mechanism integrated in a tourbillon. And in 2013, IWC’s invention makes its way into the Ingenieur watch family for the first time in the form of the IWC Ingenieur Constant-Force Tourbillon (Ref. IW590001) in a platinum and ceramic case.
Positioned at “9 o’clock”, the impressive constant-force tourbillon provides a fascinating view of its layered construction. Connoisseurs of precision mechanics will particularly enjoy watching the complex interaction of the springs, wheels and pallets. The striking black tourbillon bridge is calibrated to facilitate reading off the seconds and, like the black screws, underscores the dial’s high-tech look. As a captivating contrast to this we see the delicate, gold-coloured Glucydur beryllium alloy balance with its high-precision adjustment cam on the balance arms.
The tourbillon revolves around its own axis once every 60 seconds to offset the influence of gravity on any positional error in the balance and its adverse effect on the rate. Down in the depths of the tourbillon we see the constant-force mechanism, the true heart of the watch. This intricate assembly allows the escapement to be uncoupled from the gear train, which keeps the amplitude of the balance – and thus the watch’s rate – virtually constant.
The energy is stored temporarily in a balance spring and dispensed to the escape wheel. This balance spring is put under tension once a second, as we can see from the one-second advances made by the tourbillon hand. After every five beats of the balance, the stop wheel and the tourbillon cage are also released. The stop wheel turns and causes the tourbillon cage to rotate with it, which puts the balance spring under tension again. After about 2 days, the watch moves from constant-force mode into normal mode. Now, the second’s hand advances smoothly every one-fifth of a second. The constant-force tourbillon guarantees a regular and precise rate over a period of at least 48 hours.
The new 94800-calibre basic movement was developed entirely internally by IWC. It features two barrels, which provide the energy for the higher torque required to drive the constant-force tourbillon. It also provides the moon phase module with the necessary power. IWC’s hallmark double moon display for the northern and southern hemispheres also makes its debut in the new design. If its position on the dial is a bold statement in itself, the incredibly realistic depiction of the moon is even more daring.
IWC used a special 3-D laser technique to render the surface as authentically as possible. As a result, even tiny craters are visible to the naked eye. The countdown display on the outer ring of the totalizer shows the number of days remaining before the next full moon. A new departure for IWC is the retrograde design of the power reserve display between “4” and “5 o’clock”, which has a triangular indicator to show the power remaining. The connecting bridge was designed in such a way that the IWC logo is not concealed at any point during the watch’s 96-hour run time. The three totalizers protruding into the bezel were inspired by dash- board instruments and underscore the watch’s sporty character. In keeping with the cool, technically inspired look are the finely nuanced shades of black on the dial, the black, high-tech ceramic lugs and the solid crown protection in platinum. In the inner circle is the traditional pattern consisting of interlocking capital “I”s with elongated serifs. The letter stands for Ingenieur and lends an unusual depth to the relief.
If we look at the IWC Ingenieur Constant-Force Tourbillon from the movement side, it’s like peering into a sports car’s engine compartment. Complementing the bores in the bezel on the front side are five titanium screws with ceramic heads, which secure the sapphire-glass back firmly to the case. On the bottom plate, the lively interplay of blasted and satin-finished surfaces combined with polished edges.