The Ebosa 22, which debuted in the early 1950ies, is a remarkably well made swiss pin lever movement, of Roskopf type, which shows some interesting details.
Besides that, it belongs to the small group of pin lever movements, which are also esthetically pleasant, since it has got a stripes decoration and nickel silver coated plates.
As common on Roskopf movements, the giant mainspring barrel overlaps the center of the movement. Here, the maximum available space was perfecly used, which is very positiv for precision and power reserve.
The clever arrangement of the gears optimally uses the free space of this large, massive made movement with its large diameter of 11 1⁄2 lignes.
You can see here the Roskopf construction very well: There’s no center minute wheel, but a large driving wheel, which is driven by the mainspring barrel. The cannon pinion and the hour pinion are driven on the dial side by the exchangement wheel, which sits with a friction coupling on top of mainspring barrel.
On the Ebosa 22, all bearings contain synthetic rubis, which reduce friction and wear and thus lead to higher precision and longer power reserve times.
A very interesting detail is the adjusting mechanism for the escapement wheel bearing. In the fifties, this was history long ago, since it was once used as a simple tool for adjusting the depthing of the pin lever. Its disadvantage is, that it’s possible, that the escapement wheel axle is no longer at right angle to the bearings, which leads to additional wear of the pivots. At the end of the 19th century, such a mechanism was required to increase the low precision of the cheap made Roskopf movements.
Why Ebosa still used that technique is unknown, but it’s quaint nevertheless.
Another odd detail concerns the “screw” balance, which is surprisingly small, is non-shock-protected beared, beats with Roskopf-unlike 18000 A/h and whose hairspring key contains a long regulator arm: The “Screws” are in quotes, since they are not screws, but only imitations, consisting of a half circle.
On the down side of the balance wheel, you see, that the half-circles are no screws at all! But they look nice, though…
On the dial side you see the well made yoke winding system - this is also uncommon for pin lever movments. Unlike on other Ebosa movement, there’s even a true yoke setting lever spring used!
At “12” you see, how the hour wheel is connected with the exchangement wheel of the mainspring barrel. That’s typical for a Roskopf movement.
|Number of jewels:||15|
Nickel screw balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||2 hole(s)|
|Functions:||hour, minute, decentral second|
|Size:||11 1/2''' (measured: 25,3mm)|
Flume: 1952 23|