This Ronda “Ronda-Matic” selfwindig movement, caliber 4139, was made in the warly 1980ies. It was part of the caliber family 413x/423x/433x/443x, which was produced in different sizes, ranging from 8 3/4 up to 12 lignes, and was available as handwind and selfwindig versions. The calibet 4139 winds in one direction and uses a swiss lever movement, although it is signed as “RL”, which normally stands for Ronda pin-lever movements.
It offers all possible kinds of indications, hour, minute, second, date and weekday (in names as well as in digits from 1 to 7). The date can be quickset by a very unique mechanism: When you set the time backwards, the date advances every 30 minutes.
A big thanks to Mr. Stahl from the Ermano Uhrenwerke GmbH for identifying this movement and providing me very interesting details about it.
|Number of jewels:||21|
Nickel anular balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Hairspring key|
|Functions:||hour, minute, second, day, week day, selfwinding|