AM 630

Description

From AM, mainly round movements are known, and so the 6 3/4 ligne form movement AM 630 is a little speciality. It impresses expecially due to its beautifully slanted gear train bridge.

On closer inspecition, you can see, that all important bearings contain rubies. Interestingly, the four dial side bearings for the balance wheel, the lever, the escape wheel and the seconds wheel are made of transparent jewels. These are the bearings, you normally don’t see when you open the back of the watch.

Another noteable detail is the wasted space due to the small mainspring barrel. The shape of the caliber 630 would have made a much larger mainspring barrel possible, no idea, why it wasn’t used.

We have the usual gear train here with mainspring barrel, center minute wheel, third wheel, seconds wheel and escape wheel.

As escapement, a swiss pallet lever escapement is used.

The balance of this 1920s constructed movement is bimetallic with a slotted hoop. It is of course not yet shock protected and beats with the usual 18000 A/h. With the help of a long regulator arm, the effective length of the hairspring can be adjusted.

Of course, the AM 630 uses a yoke winding system; the setting lever spring of the specimen shown here is broken, as well, as the (but not visible on the photos) dial side bearing jewel for the balance wheel.

In the lab

Timegrapher result

The rates indicate, that the movement is in poor condition, probably mainly due to the broken bearing jewel for the balance wheel. Because of this, no further adjustment was done here.

Technical data

Usage gallery