In the late 1970ies, DuRoWe, which belonged to the Ebauches SA in that era, terminated their production of ladies’ watches form movements with their caliber 1980, also known as “INT 1980” or even as “AS 1977-5”. It was the successor of the caliber 1977-4.
The differences to its predecessor were quite a lot. The ratchet mechanism was constructed much simpler (a single, geniously shaped spring instead of a spring-loaded pawl), the balance cock got a little broader shape and the setting lever is now only spring beared, no longer secured by a screw.
The DuRoWe 1980 / INT 1980 shown here has got a nominal size of 5 1⁄2 lignes, in fact, it’s a little more, 12.9 x 15.2mm.
All bearings, except those of the slowly revolving mainspring barrel contain rubies, even the directly driven center minute wheel. On such a tiny movement, it is important to reduce friction as much as possible.
Due to the lack of space, the gear train is very stocky, in the area of the escapement wheel even two-storey. The lower bearing of the seconds wheel is not on the base plate, but above the escapement wheel. In the following photo, you can observe this:
The screw-less anular balance uses as much space as possible on this construction with directly driven center minute wheel. It beats with contemporary 21600 A/h and is beared in two Incabloc protection bearings. It regulates a classical swiss pallet lever movement.
Since on the DuRoWe 1980 (INT) the setting lever is no longer secured by a screw, but only springy, this has an impact on the setting lever spring. Its shape differes a lot from that of the DuRoWe 1977-4 (INT), especially by its second arm, which springily bears the setting lever.
Besides that, the dial side shows the contemporary standard of well constructed movements with a yoke winding system and the Incabloc shock protection.
In the lab
Timegrapher resultThe timegrapher results are very good, especially when you take into account, that it a well used specimen. In four positions, the results are within the chronometer specs, only in two vertical position, the deviation is larger, but still below 30 seconds per day. The amplitude is pretty low and and indication, that this movement is due for a service and probably a new mainspring.
|dial up||+2 s/d||235°||0.2ms|
|dial down||0 s/d||256°||0.1ms|
|crown right (12 up)||+29 s/d||213°||0.1ms|
|crown up (3 up)||-3 s/d||217°||0.2ms|
|crown left (6 up)||0 s/d||214°||0.0ms|
|crown down (9 up)||+28 s/d||209°||0.5ms|
|Number of jewels:||17|
Nickel anular balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||2 hole(s)|
|Size:||5 1/2 x 6 3/4''' (measured: 12,9 x 15,2mm)|