On the name “Bulova”, you normally think of their legendary “Accutron” tuning form movements. Far less known are the normal windup and selfwinding movements, such as the Bulova 1021.50, one of the last Bulova movements.
With a diameter of only 6 3/4 lignes (15.4mm) it belongs to the smallest windup movements, especially to the most tiny movements with center seconds indication.
In terms of quality, this 17 jewels movement is flawless, all important bearings contain synthetic rubies.
Due to the small diameter, this movement has a multi-storey structure, very comparable to small form movements. And in general, a lot of space on the sides remains unused, so the movement could also have been constructed as form movement.
The gear train is a contemporarily modern construction: The center minute wheel is driven by the mainspring barrel and followed by third wheel, seconds wheel and escape wheel, which counts 20 teeth. A driving wheel on the movement side axle of the third wheel drives the indirect center seconds axle, which is beared only one one side; on the other side a perforated flat spring holds it in position and adds enough friction to avoid a flattering center second indication.
With 21600 A/h, the tiny Bulova 1021.50 is almost a high beat movement. The modern three leg anular balance is of course shock protected, here in two Diashck bearings. Its frequency is adjusted at the hairspring key only.
The ratchet is a clever, cost-saving construction, as it consists of only one single part, the click, which is also its own spring and (flat) ball bearing. It is located in an engraving under the ratchet wheel.
On there dial side, there’s exactly, what you expect: The Bulova 1021.50 uses a yoke keyless works.
|Number of jewels:||17|
Nickel anular balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||3 hole(s)|
|Functions:||hour, minute, second|
|Size:||6 3/4''' (measured: 15,4mm)|