The Asco 375, made around 1972/1973 is one of the earliest german quartz movement with analog time indication.
With a diameter of 31mm (13 3/4 lignes) it is exceptionally large, mainly due to the large battery and the huge quartz.
Unfortunately, this specimen lacks the electronics plate, mounted above, which gives one (or two?) impulse per second to deflect the balance and put it back into the initial position afterwards.
Since this movement used only reduction stages and the required force is lower from gear to gear, only a few bearing jewels were neccessiary, only for the lever, the seconds wheel (only on the gear train bridge) and the third wheel.
The balance, which is driven actively electromechanically, advances the center seconds wheel with the help of a pin lever. A spring avoids the wheel turning backwards.
The center seconds wheel drives the third wheel, which drives the hands on the dial side.
The mechanical part of this movement was made by Durowe, and you can even see it by the fact, that the balance wheel is beared in two Duroswing shock protections, made by Durowe.
The balance, which carries the moving coil is a little masterpiece. It is powered by the hairspring on the one side, and by an ruby-isolated pin, onto which a second hairspring is attached on the movement side, from the electronics plate.
The hairspring has no effect on the precision and cannot be adjusted. Its only purpose is to deliver the electrical current and to bring back the balance into the left position, in the time between the every second pulses.
Its functionality is so the same, as on a moving coil instrument.
The two magnets can be released, like on most electromechanical movements.
At 5 o’clock you can see, how the third wheel engages with the minute wheel and drives the hands.
The minute wheel carries a slipping clutch.
The calendar mechanism of the Asco 375 is pretty modern. The date ring is beared in four metal rings (a bit like on Rolex calendar mechanisms). The switching lever is deflected by a moveable switching cam (at 7 o’clock) over the whole day and unloads instantly at midnight by a spring, advancing the date ring one step.
In the middle crown position, there’s a quickset mechanism for the date, with the help of a switching star wheel at 4 o’clock.
Although the calendar mechanism of this movement was a modern and contemporary one, it is clear, that this oddly constructed movement was no success. It was way too quirky, too sensitive, too large and too expensice. Only for collectors, it is big cinema.
|13 3/4''' (measured: 31,0mm)
|Number of jewels:
balance with coil
|Balance bearing / direction hairspring:
|yoke winding system
|Setting lever spring: