When the repeating mechanism has received the necessary information and the spring is fully wound, the performance can commence: “Mounted on the barrel arbor is a control mechanism comprising around 15 individual parts. This mechanism ensures that the hour strikes are followed by the quarters and finally the minutes,” says Kittlas, describing this intricate sub-assembly. To achieve this, the hour and quarter rack is first hooked up to the rotational of the barrel arbor through a system of drivers and disconnecting pieces. Every time one of the teeth passes a gathering pallet, it causes a hammer to strike one of the two gongs. When all the hours and quarters have been struck, the clutch system connects the minute rack to the barrel arbor and the minutes are chimed out. To ensure that the chimes are not struck too rapidly and that the speed of the sequence remains constant even when the tension in the spring is depleted, the system has a so-called governor.
The watch’s delicate tones are created when two tiny hammers strike the steel gongs, which are bent into shape and run around the periphery of the movement. The precise composition of the alloy used for the gongs as well as the methods used to make them are among the most closely guarded secrets of any specialist watch manufacturer. At IWC, too, it took countless experiments with a variety of materials until the sound met the high requirements. As with a piano string, the active, vibrating length of the spring determines the tone. Together, the gongs create a melodious fourth and have to be laboriously tuned by hand. But the case material also influences the tones heard by the owner. Red gold and yellow gold oscillate especially well. “Every single Portugieser Minute Repeater is unique and has its own unmistakable voice,” says Kittlas, not without pride.