EB 8021N

Description

Ebauches Bettlach (EB) was the manufactury under the roof of the Ebauches SA, which was responsible for simple pin lever movements.

Since pin lever movements didn’t have the best reputation because of their simpler construction and hence lower precision (with exception like the pin lever chronometers from Oris), it was attempted to improve it by putting and advertising as many jewels into it as possible.

The EB 8021N shown here, a direct relative of the EB 8021-68, belongs to the series with probably the highest number of jewels in a pin lever movement, 21 in total.

At least the base plate of this pillar movement has got jewels for all important, and even non important, bearings, but you can also spot the four blind jewels without any (technical) function at all.

The construction of the gear train was the standard one of a movement with directly driven center seconds and a directly driven center minute wheel. This wheel is located in the classical way under an own cock.

The remaining parts of the gear train could also be found in a pallet lever movement: Minute wheel, third wheel, center seconds wheel and escape wheel.

The EB-typical flat, three leg anular balance is not shock proected and has got very fragile pivots. On the specimen shown here, we have the rare exception of a not yet broken balance wheel.

It beats slowly with 18000 A/h, which can be adjusted (more or less) at the hairspring key directly.

The very well executed ratched of this rocking bar winding mechanism is located on the dial side.

You can also see the four blind jewels, which only with very, very much goodwill a slightly lower friction of the calendar ring can be thought of. In reality, this is not valid, since the date ring never has got so much friction, that it would negatively influence the precision of an imprecise pin lever movement.

The calendar mechanism is as odd as genious. A simple gear, driven by the hour wheel, makes one turn per day. Near its center ut has got a pin, which advances the date ring one position.

There’s no quickset or semi-fast correction possible, so for correcting the calendar, you have to “crank” a lot.

For locking the date ring, there’s a spring-loaded lever mechanism.

Oddly, the EB 8021N has got a date ring with red numbers. If this is the same for all versions of the EB 8021N, is unknown.

In the lab

Timegrapher result

As espected, the timegrapher result are mediocre. On a pin lever movement, only using a high number of jewels doesn’t guarantee a high accurancy.

Technical data

Usage gallery