Berger 8 3/4

Description

In the 1930ies or early 1940ies, the swiss manufactuer Berger, which is said to be a branch of Felsa AG of the Ebauches SA, produced that 8 3/4 ligne manual wind movement. In some parts of the literature, it is only called “Berger 8 3/4”, in others there are even three caliber numbers for it: Berger 16, Berger 38 and Berger 42.

The base plate offers a pleasant sight: All important bearings contain rubies (except mainspring barrel and center minute wheel, as usual) and below the balance wheel, there’s beautiful perleage.

The classical gear train impresses with its well made wheels. As usual, the mainspring barrel drives the center minute wheel, followed by third wheel, seconds wheel (which allows the use of a decentral seconds hand at 6 o’clock) and the polished steel escapement wheel.

The diameter of only 19.2mm (8 3/4 lignes) is rather small.

Nevertheless, this movement is a true swiss pallet lever movement, which is regulated by a non shock protected bimetallic screw balance, beating with 18000 A/h.

On this picture, you can very well see the two slits of the balance wheel, which makes the balance bending invard when the temperature rises. The movement of inertia descreases and compensates the temperature-decreasing tension of the blue steel hairspring.

Although the setting lever spring is broken on the specimen shown here, you can still see its characteristic shape, especially where it fixes the changing wheel.

Technical data

Usage gallery

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