Eterna 175

Description

Probably in the 1920s, Eterna released the high quality windup caliber Eterna 175.

It has got an unusual diameter of 10 lignes (10 1/2 lignes would have been the common size) and shows a well made base plate, which is even decorated around the balance wheel.

For unknown reasons, the bearing jewels of the base plate are not red, but transparent.

The gear train is classicaly constructed and reminds of small pocket watch movements, where the seconds indication is on the opposite side of the winding stem.

The mainspring barrel directly drives the center minute wheel, followed by third wheel, seconds wheel (here at position 9 o’clock) and finally the escape wheel.

As escapement, a swiss pallet lever escapement is used.

The Eterna 175 uses a slotted bimetal screw balance, which beats contemporarily slow with 18000 A/h. They can be adjusted with a long regulator arm and a beautiful scale on the balance wheel cock.

Of course, there was no shock protection yet used.

The Eterna 175 uses a yoke winding system.

On the right, there’s still the hole, where in older movement, the pin for switching the crown from winding to time setting was located. Here, there’s no need for this pin any more.

In the lab

Timegrapher result

The poor timegrapher result is due to several error of this movement: The lower seconds wheel pinion is bent, the upper bearing jewel of the third wheel is broken and the balance wheel is wobbly.

Technical data

Usage gallery