Calibre record · Manual-wind

Omega calibre 30T2

Documented

The robust 30 mm hand-wound calibre of February 1939 that began Omega's '30 mm' family — about three million movements by 1963 — and powered many Second World War service watches.

Manufacturer: Omega
Type: Manual-wind
Winding: Manual
Production: 1939–1963 (with its successors)
Country: Switzerland
Diameter: 30 mm (13 lignes)
Height: Undocumented here
Jewels: 15 (17 on some versions)
Frequency: 18,000 vph (2.5 Hz)
Power reserve: c. 44 h
Oscillator / escapement: Detached lever escapement
Complications: Small seconds (centre-seconds version 30T2 SC)

Figures are those commonly published for the standard version; individual versions and grades differ. “Undocumented here” means the value has not yet been confirmed for this record.

How it is built

A plain, generously sized hand-wound movement: Omega scaled the components to the full 30 mm rather than shrinking a pocket-watch design, which gave large wheels and bearings that are easy to service and stand up to rough use.

Small seconds at 6 o'clock in the standard version; a centre-seconds version, the 30T2 SC, appeared in 1940. Versions with 'PC' have shock protection (pare-chocs) and 'AM' marks antimagnetic construction.

History

The name describes the calibre: 30 is the diameter in millimetres and T2 the type. A centre-seconds version (30T2 SC) followed in 1940, and from 1941 shock-protected and antimagnetic versions were marked PC AM (PC for pare-chocs). In 1949 Omega gave the family three-digit numbers — the 26x series for small seconds and 28x for centre seconds — and renewed it type by type until the T6 of 1961.

Watches fitted with it

Omega dress watches of 1939 and the 1940s
Omega 'WWW' British army watches of 1945, one of the 'Dirty Dozen' makers

The numbers explained

18,000 vibrations per hour means the balance makes 5 beats (ticks) every second — 2.5 complete back-and-forth oscillations, or 2.5 Hz.
A sweeping seconds hand therefore advances in 5 small steps per second.
That is 432,000 beats a day. A watch that gains one second a day is out by about 1 part in 86,400 — roughly 11.6 parts per million.
Faster balances resist knocks and changes of position better but wear their pivots and need fresh oil sooner.

Convert beat rates and daily error with the Atlas tools · See a balance and escapement in the lab

How to recognise it

Omega signature with '30T2' on the movement and the 15 or 17 jewels stated on the plate; markings such as PC, AM or SC give the version.
After 1949 the same movements carry three-digit numbers: 260 or 261 for small seconds, 280s for centre seconds.
In military watches, a broad arrow and service numbers on the case back alongside the Omega signature.

For collectors

Thirty-millimetre Omegas are among the most affordable good vintage watches, so dial condition decides the value: many have been refinished. In military watches, check that case, dial and movement belong together.

Versions and derivatives

Versions and derivatives of the Omega calibre 30T2
Calibre	Difference
30T2 SC	Centre seconds, from 1940.
30T2 PC AM / 260	Shock-protected and antimagnetic, from 1941; numbered 260 from 1949 (261 with 17 jewels).

Compared with related calibres

Specifications of the Omega calibre 30T2 beside related calibres
Calibre	Type	Frequency	Jewels	Power reserve	Diameter	Production
Omega calibre 30T2	Manual-wind	18,000 vph (2.5 Hz)	15 (17 on some versions)	c. 44 h	30 mm (13 lignes)	1939–1963 (with its successors)
Rolex calibre 1570	Automatic	19,800 vph (2.75 Hz)	26	c. 48 h	28.5 mm (12½ lignes)	1965–c. 1977
Peseux / ETA 7001	Manual-wind (thin)	21,600 vph (3 Hz)	17	c. 42 h	23.3 mm (10½ lignes)	1970s–present

Mechanisms in this calibre

Detached lever escapement

Going barrel

Related calibres

Rolex calibre 1570

Automatic · 1965–c. 1977

Peseux / ETA 7001

Manual-wind (thin) · 1970s–present

Related records in the catalogue

Records whose titles name this calibre or a model family that used it. Earlier or later examples of a model may contain a different calibre, so check each record's description for the movement actually fitted.