Probably in the early 1970ies, Ronda launched their caliber series 10xx/11xx/12xx/13xx, which bases on the caliber 1011 and consists of two dozen combination with different features, with pin- or pallet lever and different beating speed.
To that series belongs the 12 ligne caliber Ronda 1215, a pin lever movement with date indication, center second and (here) 21 jewels.
The base plate of that movement shows, that it is not a pillar construction, but on the other hand, it’s not fully massive, too. It does not say very much about the functions and construction of the movement, but at least, all bearings, except of those for the seconds wheel and the mainspring barrel are equipped with rubies. But that’s not neccessiarly typical for this movement, which was also available with 17 and with 1 jewels.
If you hold the movement shown here into the light, you see three blind jewels, two at the mainspring barrel and one at 5:30, below the balance wheel. Three additional cap jewels are mounted within one single plate onto the movement bridge, so that finally, there are not only the usual maximum of 15 jewels for a pin lever movement, but 21 jewels:
The octogonal framing the jewels is typical for Ronda and probably an indication, that the holes were stamped and not drilled.
The Ronda 1215 has got a modern gear train, with mainspring barrel, second, third and escapement wheel. The time indication is driven on the dial side by the mainspring barrel.
Unfortunately, the anular balance of the movement is not shock protected. It works with 18000 A/h and regulates a pin lever movement.
Interestingly, the finger sits on top of the lever.
On the empty dial side, you see, that the hands will be driven by the mainspring barrel.
For a pin lever movement, it’s a bit unusual, that it uses a well made yoke winding system. Additionally, it shows a clever construction, since its spring is part of the setting lever and not an extra part.
As usual on their later movements, Ronda has got a date indication mechanism with an unusual quickset mechanism: At 1 o’clock, there’s a moveable star wheel, which only works when the time is turned back. It advances the date ring then. A moveable finger on the switching wheel at 11 o’clock ensures, that the quickset mechanism also works between 11 and 12pm and does not harm the date mechanism.
|Number of jewels:||21|
Nickel anular balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||3 hole(s)|
|Functions:||hour, minute, second, day|
|Size:||12''' (measured: 26,5mm)|
Flume: K3 -|