The Panerai Radiomir 1940 Tourbillon GMT PAM 558 was introduced in 2014. It features the P.2005 tourbillon movement housed in a red gold case of 48mm.
The Panerai P.2005 movement is Panerai's first in-house tourbillon movement in its original form. It has a second time zone in 12h format and an additional 24h indicator. The power reserve can be seen from the back.
The distinctive feature of the P.2005 calibre, entirely created by the Panerai Manufacture, is its sophisticated tourbillon regulator, a device originally designed for pocket watches, interpreted in an innovative way by Officine Panerai to achieve more accurate timekeeping. The tourbillon causes the balance wheel and escapement assembly to rotate continuously, thus correcting all the errors caused by gravity and possible friction. In the innovative Panerai tourbillon, the cage which contains the balance wheel and escapement rotates on an axis which is perpendicular to that of the balance wheel, rather than parallel to it. Additionally, while in a traditional tourbillon one rotation of the cage takes one minute, in the case of the Panerai P.2005 calibre the cage makes one rotation in 30 seconds. The greater speed and the particular arrangement of the balance wheel and escapement assembly enable it to compensate better for the running errors caused by the many vertical and horizontal positions of a wristwatch in the course of 24 hours. The tourbillon cannot be seen from the dial side, but is visible from the back of the watch; next to it is the indicator of the 6-day power reserve, displayed by a hand which moves in a circular arc. On the dial, however, as discreet proof of the presence and correct operation of the tourbillon, a small coloured disc is placed in the auxiliary small-seconds dial. Linked to the tourbillon cage, this disc moves at the same speed as the cage and therefore completes two rotations per minute.