AS 1803 (ST)

Description

The 11 1/2 ligne AS 1803 was released as so-called “Standard” caliber around 1970. It should be a cost-efficient but good quality alternative to check Roskopf movements, which especially on upcoming quartz crisis were a threat to the manufacturers under the roof of the Ebauches SA.

It bases on the caliber AS 1800 and extends it with a date indication and a semi-fast corrector.

Of course, all bearings contain rubies, even that of the center seconds pinion.

The AS 1803 (ST) already uses a modern gear train without a center minute wheel.

The mainspring barrel drives the second wheel (at 9 o’clock), which on the dial side only drives the hands. On the movement side, third wheel, directly driven center seconds wheel and escape wheel finish the gear train.

The two leg anular balance beats with 18000 A/h and is secured in two Incabloc shock protections. It regulates a swiss pallet lever escapement and can be adjusted on the hairspring key only.

On the yet empty dial side, you can see at position 3 o’clock half way to the center, the axle of the third wheel.

On this axle, mounted with a slipping clutch, there’s the wheel, which drives the hands, or to be precise, the changer wheel, which drives cannon pinion and hour pinion simulaneously. On the other side, this wheel engages with the keyless works (on the picture, the breguet clutch is missing).

The calendar mechanism uses an elaborate switching wheel (at 8 o’clock), whose switching finger is mounted moveable, so that it can realize a semi-fast calendar correction by turning the hands back an forth between 8 and 12pm.

A bit less elaborate is the lever at 11 o’clock, which locks the date ring, because its supporting spring loves to fly.

When the calendar mechanism is covered, the dial side of the AS 1803 makes a very robust appearance.

A nice detail on AS movement is the date font, which is, at least compared to ETA movements, more massive and so gives a hint, which movement (manufacturer) is used in a watch, even when you don’t yet see the movement.

Technical data

Usage gallery