Ebosa 94

Description

The Eboase 94 is a pin lever movement, which debuted in the early 1950ies.

Its speciality is, besides the high number of 15 jewels (more to that later), its indirectly driven center second - which was rather unusual at that time, especially on pin lever movements,

And also unusual for a pin lever movement is the yoke winding system, which is usually found only in (better) pallet lever movement. Maybe this, in addition to the beautiful stripes decoration, is a hint, that this pin lever movement is one of the better (best?) ones. Even the balance has got imitated screws.

The construction of the movement is a Roskopf-type, where the cannon pinion of the minute hand is indirectly driven by a non-fixed second wheel on top of the mainspring barrel. The advantage of that principle is, that the mainspring barrel can have a much larger diameter, since it can overlap the center of the main plate, as there’s no centered minute wheel to be driven from the movement side. And the larger diameter of the mainspring barrel and of the third wheel allowes the saving of one indirection step, so that there’s no second wheel any more.

You can see here the proportions of the wheel: The mainspring barrel and the third wheel are much larger, than you know them from “normal” non-Roskopf movements.

Another speciality of the Ebosa 94 is its indirectly driven center second, which is driven by the outer teeth of the fourth wheel (at 4:30). The reduction step is minimal, since the center second wheel is just a tad smaller, that the directly driven fourth wheel.

The Ebosa proudly uses 15 jewels, where, besides for the balance, three jewels are just cap jewels. One of them covers the (however much deeper located) bearing of the lever staff, and so has got no function at all.

This lever, which is pretty crude at its end, is probably not original, since its contact with the escapement wheel is much to deep, so that it completely blocks that wheel. I have no clue, why and what…

On the dial side, you can easily spot the yoke winding system with its covered setting lever (which is very watchmaker-friendly), and the three cap jewels, where the one in the middle is really useless.

Since the minute- and hour wheel are driven on the dial side only, they have to be secured by a spring, for not getting out of position on a shock. An odd solution, but efficient!

Technical data

Usage gallery