There’s not much to find out about the early Buser movements, and the Buser 318 shown here seems to be completely unknown. Probably, it was only made in very small quantities for a short period of time.
Due to the inscription on the back of the on hand watch, this 10 1/2 ligne manual wind caliber can be dated to the early 1930s.
In terms of quality, the Buser 318 was pretty well. All important bearings of the massive, already silver colored (1930 this was not yet a matter of course!) base plate contain rubies. Since the minute wheel bearing on the movement side also contains a ruby (but not the dial side bearing, which is more or less invisible), the odd number of 16 jewels was achived. At that time, 15 jewels was the usual maximum.
The well executed gear train consists as usual of the mainspring barrel, which directly drives the center minute wheel, followed by third wheel, seconds wheel at 6 o’clock (which could carry theoretically the decentral seconds hand) and finally the steel escape wheel with 15 teeth.
The escape wheel is stimm beared under an own cock.
As escapement, a swiss pallet lever escapement is used. It is regulated by a slotted bimetal screw balance. The precise beating frequency of 18000 A/h is adjusted with a long regulator arm and scale on the balance wheel cock.
Noteable on the dial side is the very small cap plate for the hands setting wheel and the setting lever angle. It hard to execute it even smaller.
At 9 o’clock you see the balance wheel bearing. Since at that time, balance wheels were not yet shock protected, it consists only a a bearing- and a cap jewel.
|Size:||10 1/2''' (measured: 23,25mm)|
|Number of jewels:||16|
bimetallic screw balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||2 hole(s)|