AM 640

Description

In the 1920s and 1930s, AM (Adolf Michel SA) was one of the largest swiss ebauche manufacturies, but after the Ebauches AG merge, they kind of vanished and today, only very few people still know about them.

The rectangular caliber AM 640, a form movement with a width of 6 3/4 from the 1920s is the base caliber of the caliber family of the same name.

It is unusual for the 1920s and 1930s, that this movement was available with 17 jewels, too. Here, the minute wheel was beared in two ruby bearings.

As expected, this pallet lever movement was well made, and of course all important bearings contained rubies, so that it used in total 15 or 17 jewels.

It is nice to see, how, because of the age of this movement, all ruby bearings were still edged and not just plugged into the plates.

Although the available space was not completely used, the rectangular shaped allowed the usage of large wheels. Their arrangement follows the usual scheme mainspring barrel - center minute wheel - third wheel - seconds wheel - escape wheel.

The crown wheel has got a left-hand thread (not marked).

The two leg screw balance (bimetal or monometallic) is of course not yet shock protected. It beats with 18000 A/h and can be regulated with a long regulator arm.

As escapement, a swiss pallet lever escapement is used.

Of course, the AM 640 uses a yoke keyless works (whose setting lever spring is unfortunately broken on the specimen shown here).

The 17j version has got the AM hallmark on the dial side, which makes the identification of the movement a little bit easier.

Technical data

Usage gallery