Desa (Ebauches Desa) was one of the manufacturers of pin lever movements, which are rare to find, although their movements have got exactly the same constructions as those of many other manufacturers like Baumgartner.
The Desa 321 presented here is such a pin lever movement, which is built on a large 13 ligne base plate. It belongs to the caliber family 220⁄320, whose base movement has got a diameter of only 12 lignes, but is otherwise identical.
The base plate shows the construction with transmission wheel on the base plate. The yoke winding system with its lever and spring can also be seen here.
There are no jewels on this movement, even the balance uses a simple brass finger instead of a ruby ellipse.
At 6 o’clock, there’s the riveted decentral seconds hand. It cannot be removed.
The gear train of the Desa 321 follows the Roskopf construction with the extra large mainspring barrel, which covers the center of the base plate. Because of this, one transmission step could be saved.
The decentral seconds hand, which has got a smaller diameter than the second intermediate weel, is driven by the outer rims each.
This Roskopf construction is also the reason, why the non shock-protected anular balance beats with the crooked number of 17280 A/h. The escapement is a traditional pin lever escapement.
Since a Roskopf movement uses no conventional hand gear train on the dial side, the hands have to be driven alternatively. For efficiency reasons, this is achived with two additional gears on top of the mainspring barrel.
The two gears are connected to the mainspring barrel with a slipping clutch.
Cannon pinion and hour wheel are both axle beared and driven by the barrel cover with minute wheel.
There’s no shock protection or ruby bearing for the balance wheel and gears, but on the other hand, the Desa 321 uses a real yoke winding system, like “better” movements do.
In the lab
Nickel anular balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||pillar construction|
|Winding mechanism:||yoke winding system|
|Functions:||hour, minute, decentral second|
|Size:||13''' (measured: 30,6mm)|
Flume: K3 -|