AS 655

Description

The AS 655, a 5 1/4 ligne form movement in brass color dates from the 1930s, which can be confirmed by the use of the Ebauches Trust hallmark on the dial side. This hallmark was used by the Ebauches SA, the roof organization of many swiss ebauche manufacturers.

The german trading company Zentra used this movement for their high quality ladies’ watches and gave it their own caliber name Zentra 175.

Of course, this movement is technically well made, which can be seen e.g. on the use of deep red rubies on all important bearings.

The gear train construction is typical for this kind of form movements: The mainspring barrel drives the center minute wheel, followed by the two small third- and seconds wheels, and finally the again normally-sized escape wheel for the pallet lever escapement.

For space reasons, the lower seconds wheel bearing is located above the escape wheel, so we have a 1 1/2 storey construction.

There’s also an oddity on the ratchet wheel: Its screw has got a left-hand thread, but here it does not use the usual three slots, but only one.

The monometallic screw balance beats contemporarily slow with 18.000 A/h, which can be adjusted with the help of a long regulator arm. Of course, a shock protection was not yet used.

On the dial side, one can see the yoke winding mechanism, as well as a partial auxiliary minute track, which could be helpful in adjusting the movement before it was installed.

The fact that this movement bears the Ebauches Trust hallark allows it to be dated to the period between 1936 (introduction of the Ebauches Trust allmark) and 1939 (replacement by individual manufacturer hallmarks).

In the lab

Timegrapher result

Visually, this movement is in very good condition, but on the timegrapher, the results are very poor. Probably, the balance wheel is either too much work out or even damaged. This could also explain the large amplitude differences between horizontal and vertical positions.

Technical data

Usage gallery