Calibre 2310 was a popular chronograph movement from Lemania.
In the 1940's, Lemania and Omega worked together on a project called "27 CHRO C12" to develop a 27 mm diameter chronograph with a 12-hour register. Lead by Albert Piguet and Jaques Reymond, this project resulted in the 1942 launch of the Lemania 2310, called Calibre 321 by Omega.
Cal. 2310 was a column wheel design with a screwed balance oscillating at 18,000 A/h. It has a distinctive "wishbone" shaped bridge that makes it recognizable to many.
This movement was famously used in the Omega Speedmaster from 1957 through 1965 as well as the Omega Speedmaster Professional from 1965 through 1968, where it gained fame as the "moon watch" movement. It was also used in the Omega DeVille, Omega Seamaster, and watches from Patek Philippe (as Cal. 2872).
The cam switching Lemania 1872 family replaced the 2310 for most applications beginning in 1968.
Calibre 2320
The Lemania 2320 was closely related but included a swan neck regulator, 4 extra jewels (21 total), and other refinements.
Variants
Calibres 2310 and 2320 are used as the ebauche and base design for the many prized chronograph movements from names like Patek Philippe, Vacheron Constantin, Breguet, and Roger Dubuis. It is widely regarded as one of the finest such movement designs in history.
Lemania 2310 variants
Patek Philippe 2872
Patek Philippe CH 27-70
Omega 321
Lemania 2320 variants
Vacheron Constantin 1141, 141, and 141q
Patek Philippe 27-70q
Breguet 533.2
