Jorn from Norway sent in this great looking Seamaster Chronograph. It has the not so common calibre 1040, which is only very loosely based on the 321. This is one of Omegas most elaborate chronograph movements, with the following features:
- 60 minute central minute recorder placed under the minute hand, moving continually
- 12 hour recorder at 6 o’clock, turning continually
- sub-second hand at 9 o’clock
- 24 hour indicator at 9 o’clock
- automatic winder
The bottom plate is an entirely different beast, though. There is a little bit of clear plastic debris at 2o’clock close to the centre.
With both sub-plates removed, we can now see the clutch mechanism for the minute recorder. The minute hand and the minute recorder are coupled together with a friction clutch. In normal, non-chrono operation, the minute recorder is blocked by the two big levers with springs, that press against it to keep in on 0 position. When the chronograph is started, the piece in the middle is pulled down, thus releasing the two levers that brake the recorder, and it starts moving together with the minute hand.
This looks familiar, as a lot of elements are taken from the 321. But there are distinct differences. The escape wheel doesn’t have a cock of its own, but is held by the wheel bridge. The round opening at 5 o’clock is for the auto winder reverser wheel, which has a planetary wheel construction to allow winding in both directions. This is a quite unique and smart construction, and for a retrofitted auto winder, a great solution.
I clean the case, polish the crystal, take apart the pushers and put in new gaskets, and case the movement, and we’re back in business.