In the early 1952ies, the production of selfwinding movements started in Germany. Although is was not the first one on the market, the Durowe 552 marked the start of the extremely successful series of selfwinding movements from the Deutsche UhrenRohwerke, which were improved many times in important details. The Durowe 552 shown here is the forefather, born in 1952.
The base plate is the same as on the manual wind movement Durowe 522, which itself is nothing but a Durowe 422 with a larger base plate. And a relative of this one is (with date indication) the Durowe 435, which is already in the archive.
As usual in these times, the directly driven minute wheel is beared under its own bridge, in the specimen show here even ruby-beared.
Of course, all further bearings are also equipped with synthetic rubies, so this is clearly an upper class movement.
The directly driven center second was up-to-date that time.
The shock protected screw balance is beared in two inhouse Duroswing shock protections and beats contemporarily slow with 18000 A/h. It regulares a conventional lever movement of swiss type.
The selfwinding module is attached with three screws on the base movement and can be released easily. The connectin between ratchet wheel and first reduction wheel is realized by a vertical breguet clutch, sitting on the reduction wheel. It works exactly like the breguet clutch of the yoke winding system:
With that clutch, the sensitive selfwinding mechanism is decoupled on manual wind. How delicate that mechanism is, can be seen on the first reduction wheel, whose outer gears are already damaged, probably by a blocking. You can see this problem on several old Duromats.
The gear train consists or two reductions wheels with a rocking bar changer, which ensured, that no matter in which direction the oscillating weight turns, the reduction wheels always turn in only one direction and so wind the movement. The difficult to mount clutch is always under (spring-) tension and avoids backward turning of the oscillating weight.
In later movements, the rocking bar changer got a second bearing (both with rubies then) and was located under an own bridge. This makes servicing much easier!
The oscillating weight is axle beared.
Without the mounted selfwinding module, you can easily see the relationshop to the related manual wind movements from Durowe. The additional ruby next to the ratchet wheel for connection of the selfwinding module is the only visible difference.
A final viel with attached selfwinding module but missing oscillating weight, which is secured by a chock with two screws. The movement is almost fully covered.
On the dial side, you can see the yoke winding system. On the specimen shown here, the setting lever spring is broken. You can also see the cap jewels for escapement- and third wheel. Theoretically, it is even possible to cover the lever bearing with a cap jewel, since the recess on the main plate is already there.
In the lab
|dial up||+5 s/d||223°||3.0ms|
|dial down||+12 s/d||226°||3.3ms|
|crown right (12 up)||-30 s/d||180°||4.3ms|
|crown up (3 up)||+47 s/d||175°||4.6ms|
|crown left (6 up)||+36 s/d||170°||4.8ms|
|crown down (9 up)||+29 s/d||176°||3.8ms|
|Number of jewels:||25|
Nickel screw balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||solid construction|
|Winding mechanism:||rocking bar winding system|
|Setting lever spring:||3 hole(s)|
|Functions:||hour, minute, second, selfwinding|
|Production period:||1952 - 1956|
Flume: 1952 65|