Yo no controlo mucho, pero creo que puede ser un Unitas 271 o familia. En cuanto a fecha, el 273 que se muestra en la biblia rosa indica que es de en torno a 1930. De todas formas, seguro que los expertos te lo aclaran en cuanto se pasen.
Fig. 1
Fig. 2
[SIZE=+1]
Unitas 271[/SIZE]
Features
stem wind and set
sub second
Data
18.5''' (18.5...21'''), Dm= 41.0mm, Do= 41.6mm
H= 5.3mm
15 jewels
f = 18000 A/h
power reserve 33h
Balance staff U1087 / U1161
hairspring collet 0.9/0.8mm
Stem W1491
Mainspring / battery
Zf3583, 2.10 x 17.0 x 0.21 x 490mm
Hands
2.00 x 1.15 / 0.26mm
Comments about the data
Remarks
open face calibre
option: Breguet hairspring
different bridge shapes (cf. other calibres of the family)
differences not known between 231, 235, 239, 243, 249, 255, 259, 265, 271, 277, 447, 449, 471, 477, 508
family/generations:
29 : open face, H= 6.5mm
30 : hunter, H= 6.5mm
31 : open face, H= 5.3mm
32 : hunter, H= 5.3mm
33 : open face, H= 4.15mm
34 : hunter, H= 4.15mm
231: like 31, but bigger barrel
233: like 33, but bigger barrel
234: like 34, but bigger barrel
245: open face, H= 4.7mm
362: hunter, H= 4.7mm
426: sweep second, H= 7.9mm
429: like 29, new balance, wider mainspring
430: like 30, new balance, wider mainspring
431: like 245, but new barrel
432: like 362, but new barrel
Example, year: signature; shock device
ca. 1930: 55, 273