[dropcap size=small]F[/dropcap]or centuries, watchmakers have been working to eliminate force variations in movements. Because the force or torque that the mainspring delivers as it unwinds is not consistent (it’s higher when the watch is fully wound and diminishes as it winds down), it’s always exciting to see the various ways it has been tackled. One of the latest such attempts to catch our eye is IWC‘s Portugieser Constant-Force Tourbillon.
MATTER OF CHOICE The Portugieser Constant-Force Tourbillon shown here has a platinum case and a black dial, but other options are available – scroll through the gallery for more.
IWC’s patented constant force-integrated tourbillon first appeared in the ultra-complicated Portugieser Siderale Scafusia in 2011, and again in 2013 with the Ingenieur Constant-Force Tourbillon. Bearing the same Calibre 94800 of the now-discontinued latter model, the tourbillon has a small spring mounted under the escape wheel that accumulates and releases power from the mainspring once a second. This gives the balance constant amplitude and also causes the tourbillon cage to advance in one-second jumps. This ensures an extremely regular and precise rate over approximately two days (out of a four-day power reserve), after which the movement reverts to normal mode.
Like the Portugieser Siderale Scafusia, the Portugieser Constant-Force Tourbillon offers customisability, though at a lesser extent. You will be able to choose a platinum or red gold case with four dial choices per case type, and options for caseback engravings and Santoni leather straps are also available to go with the 46mm wide, 13mm thick watch. The entire process is expected to take about three months, from the first point of contact to delivery.