AS 1950 (ST)
Description
Around 1970, the 11 1/2 ligne AS 1950 (ST) was launched as so called “Standard” caliber.
These movements with their identical positions for the dial feet and crown stems, should make it easier for watch manufacturers to chose a movement of the broad selection from Ebauches SA movements and their different manufacturers.
It was the successor of the caliber series 1800, and got a higher beating frequency of now 21600 A/h.
base plate
In terms of quality, there’s nothing bad to say about this movement. All important bearings, including those for the decentral minute wheel and center seconds wheel contain rubies.
gear train
The speciality of this movement is, that the mainspring barrel drives a decentral minute wheel, which is located near the crown, followed by third wheel, center seconds wheel and escape wheel.
With that construction, the movement could be made pretty flat (only 4.5mm in height) and lots of space remained unused, which can easily be seen.
side view of the gear train
A modern, three-leg anular balance is used, which is beared in two Incabloc shock protections and beats semi-fast with 21600 A/h. The adjustment can be made on the hairspring key only.
As escapement, of course a swiss pallet lever is used.
AS 1950 (ST): Dial side
The hands are driven indirectly by the decentral minute wheel at position 3 o’clock, on whose axle the cannon pinion is mounted with a slipping clutch. The cannon pinion drives the exchange wheel, which turns both hands, hour- and minute hand simultaneously.
The slightly slanted edge of the base plate saves a little height, since extra flat watches still were popular that time.
The pretty raw execution with its crude traces reveals, that the swiss watch industry was already in touble that that and costs had to be cut wherever possible.
In the lab
Timegrapher result
Apart from one exception, the timegrapher rates are pretty good.| horizontal positions | |||
|---|---|---|---|
| dial up | -1 s/d | 309° | 0.1ms |
| dial down | +-0 s/d | 302° | 0.1ms |
| vertical positions | |||
| crown right (12 up) | -9 s/d | 280° | 0.0ms |
| crown up (3 up) | -20 s/d | 273° | 0.0ms |
| crown left (6 up) | -4 s/d | 276° | 0.3ms |
| crown down (9 up) | +8 s/d | 275° | 0.3ms |
Technical data
| Manufacturer: | AS |
| Caliber: | 1950 (ST) |
| Caliber base: | AS 1940 |
| Size: | 11 1/2''' (measured: 25,5mm) |
| Height: | 4,50mm |
| A/h: | 21600 |
| Number of jewels: | 17 |
| Escapement: | Pallet lever |
| Balance types: |
monometallic anular balance (three legs) |
| Shock protection(s): |
Incabloc |
| Balance bearing / direction hairspring: | Clockwise |
| Moveable stud: | yes |
| Adjust mechanism: | Hairspring key |
| Construction: |
|
| Construction type: | solid construction |
| Winding mechanism: | yoke winding system |
| Setting lever spring: | 1 hole(s) |
| Attachment of setting lever: | screwed |
| Features: |
|
| References: |
Flume: K3 36 |
| Documentation (years): | 1976 |
| Inventory number: | 23065 |
Related Movements
- AS 1940 (ST) : 21.600 A/h, 10 1/2 ligne diameter
- AS 1941 (ST) : date indication, countersunk in plate
- AS 1950 (ST) : larger base plate with 11 1/2 lignes diameter, no date indication
- AS 1951 (ST) : date indication, countersunk in plate