Bulova 8 AC

Description

The American Bulova 8 AC, nominally listed as having 8 x 10 lines, but actually measuring 18.2 x 20.2 mm (more like 8 x 9 lines), was probably manufactured around 1950.

Its design with mirror-polished bridges makes it appear quite modern for the time, while its concealed winding mechanism (Patek system) is rather old-fashioned.

Of course, all the important bearings in this movement are equipped with jewels; it is very nice to see how the balance wheel, anchor and escape wheel are aligned.

The gear train construction is quite classic: The mainspring directly drives the central minute wheel, followed by the third wheel, the seconds wheel at 6 o’clock, and finally the escape wheel.

A Swiss pallet fork escapement is used.

The beautiful gold-colored Glucydur screw balance, in combination with the mirrored bridges, creates a high-end look, but unfortunately, it is not yet shock-protected.

The balance spring, which is fixed to the balance cock, has a Breguet terminal curve into which the hairspring key engages. At its other end is the long regulator arm, which should allow for precise adjustment of the beat rate of 18,000 A/h. As a finishing touch, even the scale on the balance cock is gold-colored.

As mentioned above, the Bulova 8 AC uses a concealed winding mechanism, in which the crown wheel and ratchet are located on the inside of the mainspring barrel bridge. The advantages of this design are likely all visual; technically, the extended mainspring barrel axle, which is now mounted above the ratchet wheel, might offer some benefit against premature wear, but whether this is actually the case is unknown.

On the dial side, one finds the expected scene: A mirrored plate, clutch winding mechanism, and two cap jewels for the balance wheel and escape wheel bearings. Technically, this is very close to the optimum; additional cap jewels offer little practical improvement, at least not in this simple plate-like form.

In the lab

Technical data

Usage gallery