Osco (Otto Schlund) in Schwenningen was one of the large ebauche factories in Germany, which was especially important in the cooperation “Parat”. However, there was only one single series of selfwinding movements, which consts of only two members, the caliber 1064 and the caliber 1065 without date indication, shown here.
Both movements base on the manual wind movement Osco 1060.
As you can see on the image, the base plate was enlarged for the oscillating weight to a diameter of 11 1/2 lignes.
The gear train is fully beared in ruby bearings and has got a contemporary construction with a central and directly drive minute wheel, located under its own cock, and a directly driven center second.
The two-storey construction is space-saving, you can see, that large parts of the massive base plate are not covered by wheels.
The Osco 1065 has got a screw balance with two long, slightly curved legs, which beats with 18000 A/h and is normally beared in two Rufarex Shock protection bearings. But there are exceptions, the specimen shown here uses a pair of Rufasuper bearings, which at least visually remind a bit of Incabloc shock protections.
The selfwinding mechanism consists of an axle beared oscillating weight, which drives the crown wheel with a rocking bar and two reduction wheels. The first reduction wheel is interfered by a pawl to avoid running out.
The second, large reduction wheel has got a commutator clutch on its lower side, which decouples the selfwinding gears on manual wind.
This mechanism is as simple as genious!
The complete selfwinding module can be released from the movement; all bearings contain rubies.
The oscillating weight is axle beared.
As long as the selfwinding module is not mounted, you can see the relationship to the Osco 1060, the two biggest diferences is the larger diameter of the base plate and the additional bearing next to the crown wheel for connection of the selfwinding mechanism.
A final image with mounted selfwinding module, but missing oscillating weight:
On the dial side, you can see the yoke winding system and the closed exchange wheel for driving the hour wheel. On the bevelled edge, there’s space for a date ring, but this is only available onn the Osco 1064.
In the lab
|Number of jewels:||25|
Nickel screw balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||1 hole(s)|
Flume: 1962 74|