Index:

Models:

Seamaster
Speedmaster
Constellations
De Villes
Dynamics
Miscellaneous

Chronometer Grade Movements
How a Bumper Wind Movement Works
Some side Notes on Some of the Movements
Omega and ETA/Lemania
Movements Through the Years
Automatic Movements and when they were Introduced

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Seamasters
Watch	Caliber
Professional	1120
Professional Quartz	1438, 1538
Professional Chronograph	1154
GMT	1128
Omegamatic	1400
Chronograph	1154
Ladies Quartz	1424
Vintage	342, 352, 353, 354, 420, 471, 500, 501, 550, 552, 562, 564, 565, 591, 601, 679, 720, 752
Vintage Chronograph	321, 861, 1040
Vintage Seamaster De Ville	550, 610, 711
Electronic f300Hz	1250, 1255
600	601
300	552, 565
200	1002
120	565, 1120
60	565
30	267, 286, 269
Cosmic	565, 1012
f300Hz	1250
Polprof	1002

Speedmasters
Watch	Caliber
Professional	321, 861, 863,  864, 866, 867, 1040, 1861, 1863
Professional Moon Phase	1866
Automatic	1040, 1045, 1140, 1141, 1151, 1152, 1155, 1160
125	1041
X-33	1666
Supersonic	1255
Quartz	1620

Constellations
Watch	Caliber
Automatic	1120
95 Quartz	1532
Perpetual Calendar	1680
Chronograph	Piguet 1270
Carre	1376
Ladies Small & Mini	1456
Ladies Automatic	2520
Vintage	354, 505, 551, 552, 560, 561, 562, 563, 564, 565, 751, 1001, 1011, 1012, 1310, 1330
f300Hz, and f2.4MHz	1250, 1255

De Villes
Watch	Caliber
Current Models	1120, 651, 1538, 1424
Co-axial	2500
Prestige Chronograph	861
Vintage	620, 661, 671, 684, 752
Chronometer 300 Hz	1250

Dynamics
Watch	Caliber
Chronograph	1138
1990s Version	1108
Vintage	565

Miscellaneous
Watch	Caliber
Bumper Wind	28.10 RA PC (first automatic Omega), 333, 342, 343, 351, 354, 355
Manual Wind	17.8-SC, 23.4, SC, 25.5 SOB, 26.5 S, 28, 231, 265, 266, 267, 268, 284, 269, 283, 286, 302, 600, 601, 611, 620
Automatics	471, 563, 6101 RA, 562, 750
30 mm Movements	265, 266, 269, 283, 284, 286
Museum Collection (5700.50.07)	2200
Flightmaster	910 and 911
Chronostop	865
Megaquartz	1310
Vintage Moon Phase	381
Ladies Vintage	11.5, 244, 482, 484, 485, 625, 671, 684
Ladymatic	450 and 455
Tank Style Watches	T.17, P. 17.8, R 17.8, 19.4, 20.F, 27.3 S, 302, 671,
Railmaster	552
Globemaster	501
Aviator	35.5 S-T1
Century	283
Memomatic	980
Geneve	491, 552, 555, 601,  600, 601, 613, 1030, 1481
Grand Luxe	504
Chronograph	33,3 CHRO
Chronoquartz	1611
Pocket Watches	19''' LO, 38,5 Lépine T1, 140, 37.5 L-15 R, 37.5 T1
Split Second Pocket Watch	1130
Stop Watch	8260 A

 

Chronometer Grade Movements

For a watch to earn the title of "chronometer", the movement has to pass a very strict battery of test under very strict control at the most renowned official testing organization, the C.O.S.C (Controle Officiel Suisse des Chronometres). The testing last for 15 consecutive days. For the first ten days, the movements are tested in five positions at 20 degrees Centigrade. Three of the positions are vertical: 3 o'clock left, 3 o'clock up, and 3 o'clock down. Two test are horizontal: dial up and dial down.

After that, the movement is left in the horizontal, dial up position, and the temperature is lowered to 4 degrees Celsius for one day. Then it is raised back to 20 degrees Celsius for one day. Then the temperature is increased to 36 degrees Celsius. For the last two days of the test, the movement is moved back to vertical 3 o'clock left position and the temperature is lowered back to 20 degrees Celsius.

The timekeeping of the movement is recorded daily, and at the end of the 15 day test, calculations are made in six different areas. The different areas are:

1. mean daily rate in the different positions.

2. mean variation.

3. maximum variation.

4. greatest difference between the mean daily rate and any individual rate.

5. variation of rate per 1 degree Celsius.

6. resumption of rate.

The variances allowed are very small. The mean daily rate must be within -4 and +6 seconds per 24 hours. The only chronometer grade movements by Omega that I am aware of are: 28.10 RA, 331, 340, 354, 551, 560, 561, 562, 563, 564, 672, 682, 712, 864, 1001, 1011, 1021, 1041, f300Hz.

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How a Bumper Wind Movement Works

Bumper wind,  a.k.a. hammer wind movements, are early automatics. In today's automatics, you have what is called a "full rotor" automatic. What this means, is that the rotor can go around the whole movement to wind the mainspring. But back in the early part of the 1900s, they didn't know how to make a full rotor automatic. The concept of the bumper wind came about in the 1920s by John Harwood. The rotor in a bumper wind swings around about 120-130 degrees. There were two draw backs to this movement, the first one is that it isn't the best system of winding. It takes a lot of wear to wind one completely. That's because the rotor, a.k.a. hammer mass, always wants to go in the direction of the mainspring. To compensate for this, watchmakers had to evenly place weights on the bottom part of the rotor. That way when the wearer moves their wrist, the rotor will be pulled away from the barrel bridge so that the watch could wind. The second is that the constant slamming of the rotor on to the winding bridge causes wear on the parts. The term "bumper wind" comes from the bump you feel when the rotor returns to the winding bridge.

Here is a picture of the movement in my Omega bumper wind:

Differences between the 28.10 RA PC and 28.10 RA SC PC was the center seconds of the 28.10RA SC PC.

The 342 was in the first Seamaster.  The 342 is identical to the 28.10 RA PC, but used concealed buffer springs. The 354 was identical to the 342, but used a swan neck regulator.  355 was the 354 with a date feature.

The 28.10 was a unidirectional wind.

The 501 is identical to the 471, but with swan neck regulator.

The 750 is a modified 550.

The 470 and 490 were the first Omega with rotor wind (360 degrees) winding bi-directionally.

471 was Omega's first full rotor automatic.

The first Constellation was introduced in 1952 with a Pie Pan dial, and 28.10 RA movement.

The base caliber in the Dynamic Chronograph is the ETA 2890-A2, and the chronograph movement is Dubois-Depraz 2030.

Besides adding a Geneve wave decor to the 1120 movement, and polishing the parts, Omega also adds their own winding rotor to the movement.
 

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