But how did this particular design achieve such a splendid reputation among IWC's peers in the watch industry? By using a heart-shaped eccentric similar to the one already found in watchmaking as the cam for resetting a chronograph, it was possible to maximize the energy yield. Other designs used a complicated reducing gear to transmit the energy produced by the movement of the rotor to the barrel. But this led to losses of power and efficiency. The heart-shaped, eccentrically mounted cam adopted by Pellaton was by far the best design to date because it converted the revolutions of the rotor into the to-and-fro motions of a rocking bar.
This movement was then transferred to the winding wheel by two pawls. While one of them pulls the wheel (i.e. winds it), the other glides smoothly over the top of it until the roles are reversed. The design was not only rugged and efficient but was also considered extremely service-friendly. Wearers of an IWC automatic watch with Pellaton winding can experience the same level of efficiency to this day. Every single movement is transmitted as energy via the Pellaton winding to the barrel, and the watch is wound up very quickly.
In the late 1940s, Albert Pellaton and his team set about putting the innovative designs for the self-winding mechanism to work in the development of series-production watch movements. From the records, we know that IWC was subsequently planning to make three movements with automatic winding: the 81, 85 and 99 calibres. All that remains of the last-named movement are a few of Pellaton's sketches, and development never got beyond the project stage.
The plan was to go into production with one movement featuring a small seconds hand, the 81 calibre, and another with a central seconds. The first of these, however, was never to be realized, despite the fact that designs had been drawn up and plans made for parts production and other components. In the company movement number records, 1800 numbers had been reserved for the movement with the small seconds hand. The records, however, contain no indication of a single sale. We can only assume, therefore, that the 81 calibre never went into series product and that IWC immediately started focussing all its efforts on production of automatic movements with the 85 calibre.
For most people back then, the 81 and 85 calibres were very closely related. In the movement number records, the "C 81" entry for the 2250 series was summarily replaced by a "C 85". We can only speculate as to the reason series production never got under way despite the fact that development was so far advanced. It was probably thought that an automatic movement with a small seconds hand would never be a market success. Another possibility is that the production costs were higher than for the 81 and a spontaneous decision was made to shelve sales of the 81-calibre movements. The 85 calibre with a central seconds hand went into production in 1950 and further improved in the course of time.