Accompanied by power supply and cable.
Jämes Cäsar Pellaton, better known as James C. Pellaton, born in LeLocle in 1873, is one of the most esteemed 20th century maker of tourbillon carriages. He learned his craft from his father Albert Pellaton-Favre (1832-1914), also a highly respected tourbillon maker.
The over 35 tourbillons which James and Albert Pellaton manufactured together alone for Patek Philippe are a class apart in the area of precision horology. In addition to the outstanding result obtained, these timepieces are distinguished by their esthetical concept combined with the highest technical perfection and craftsmanship.
James Pellaton's life was dedicated to his passion, the development of tourbillons, which included the smallest tourbillon watch with a diameter of only 23.7 mm. in 1923. The watch, at the time the smallest ever made, is today in the LeLocle Museum of Horlogy.
Pellaton was a highly appreciated teacher at the Technicum LeLocle, and contributed with his exceptional knowledge in the field of horology and his outstanding skills as a teacher to the excellent reputation of this watchmaker school. In 1925 he was promoted director and remained in this position until his retirement in 1939.
For his outstanding work in the field of horology Pellaton received numerous awards and titles, amongst them "Doctor Honoris Causa" of the University of Neuchâtel.
The present chronometer was most probably designed for the San Francisco World Exhibition in 1915. It appears that James Pellaton had to renounce due to technical difficulties, which made it impossible to meet the deadline for the show.
The system had at the time of its invention, around 1913, two major problems, one being the low capacity of the batteries available during this epoch, which allowed the chronometer to run only a few hours. The second obstacle was the, again at the time, available contact material which was not able to support the amount of current and consequently oxidized rapidly. Alas Pellaton never saw his masterpiece run before his dead in 1954 as both problems could not be solved during his lifetime.
The electrical supply delivered with the present watch was developed in 1962 only. It contained a cold cathode Tyraston valve, which when triggered by a low voltage, would allow a high current to pass to activate the solenoid. The system was perfect for Pellaton's chronometer since the trigger voltage was low with only a small current. It solved the contact problem and as the power source could be connected to 220V (or 110V), battery failure was no longer an issue.
Remontoir à force constante or constant force winding
The main spring of the present watch is rewound every 7 seconds via a solenoid (electric conductor) by using an electrical force, resulting in a nearly constant tension of the spring. By avoiding a loss of tension this construction works as a "remontoir à force constante".
The conventional main spring is replaced by a helical spring, which provides the driving force for the balance wheel.
One of the lever arms has a solenoid on the pivot's right side, pulling the lever arm down and stretching the helical spring on the lever arm's left side. The spring forces the drive pawl to rotate the ratchet wheel, which drives the balance wheel via a gear train. The ratchet wheel is fitted with a non-return pawl in order to prevent it from turning in the wrong direction.
The pawls are connected together electrically. While rotating the ratchet wheel, the drive pawl descends and will close the contact just before the end of its movement. At this instant the non-return pawl is at its high point and its contact is open as it passes over the next tooth on the ratchet wheel. It closes the contact when dropping into the root of the next tooth.
To reactivate the process the solenoid must be energized to pull the lever down to restart the cycle. One side of the solenoid coil is connected directly to the power supply, the other end to the contact on the non-return pawl, which is in series with the drive pawl, one side of which is branched to the other connection of the power supply hence both contacts have to be closed to provide power to the solenoid.
The adjustments of the contacts on the two pawls determine the exact moment the solenoid is energized. The two contacts are in series and both are only closed just as the non-return pawl falls into the root of the next tooth of the ratchet wheel. At this moment the solenoid is energized pulling the lever arm, which in turn pulls the drive pawl up breaking the contact cutting the power to the solenoid, hence the cycle restarts.