In the late 1950ies, when selfwindig movement were en vogue, the swiss Ebauches Bettlach, which, due to certain laws, was only allowed to product pin lever movement, also released an own selfwinding movement - the caliber EB 1575N described here. This movement bases on the handwound caliber EB 1504.
Unlike the caliber 1504, the diameter of the base plate was increased from 8 1⁄2 to 11 1⁄2 lignes to offer enough space for a large oscillating weight.
The gears and trains are still a Roskopf construction with only three gears. Additionally, the indirect center seconds indication is driven by the outer gears of the second wheel, which runs counter clockwise and with a different rotation speed.
Thr ring balance in beared in two KIF Protechoc shock protection bearings, which contains metal plates instead of synthetic rubies. Unlike a true Roskopf movement, it already beats with 18000 A/h. The movement is regulated then by a pin lever.
There are no bearing rubies in that movement, only the ellipse stone of the balance is made of synthetic ruby.
The selfwindig mechanism is simple but efficient: The oscillating weight has got a sliding clutch, which is responsible for the unidirectional winding and the decoupling when the movement is hand wound. With only two reductions gears, the energy is transmitted to the mainspring wheel. To avoid a backwards running oscillation weight, a pawl is attached to the gear next to the oscillating weight.
On the yet empty dial side, you can see the bridge for the center seconds indication and the bearing axels for minute and hour wheel.
As usual on Roskopf movements, minute and hour wheel are directly driven by the mainspring barrel, on which the driving and changing wheel is frictionally coupled.
The setting lever spring is uniquely shaped and contains on its lower side an own spring. So it doesn’t require any external springs.
|Number of jewels:||1|
Nickel anular balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||pillar construction|
|Winding mechanism:||yoke winding system|
|Functions:||hour, minute, second, selfwinding|
|Production period:||1958 - 196x|
Flume: K2 1962 77|