The EB 8027 is a typical pin lever movement of the
Ebauches Bettlach, which is considerably finer made than other pin lever
movements and impresses with the extraordinary high number of 23 jewels.
Like most other EB pin lever movement, the EB 8027 uses an extra flat and light ring
balance, too. Its torque is pretty low, nevertheless even these movements are capable
for daily use. The watch shown at the bottom of the page can tell you stories...
A speciality of the specimen shown here is, that the three leg ring balance is beared in two
shock protections, probably Trishock. And besides that, the whole balance system with its
moveable hairspring stud seems to originate from a "better" watch than an EB pin lever
movement.
motion works
The construction of that movement, which probably originates from the 1960ies is
contemporarily modern with a directly driven center second and a minute wheel, which is
located under its own bridge.
side view
The movement is a so called pier construction, which means, that between
the thin main plate and the upper bridges, there are only pillars. This saves a lot of
money, but is of course less stable and sturdy.
main plate
All bearings, even of the hour changing wheel, contain synthetic rubies.
From a technically point of view, there's no need for such a bearing on the
mainspring barrel nor on the hour changing wheel, and even the cap jewel of the
third wheel is not really neccessiary.
The escapement wheel bearing has got a cap jewel only on the movement side, but not on the
dial side. The reason for that oddity is unknown, but maybe 24 jewels would have become
rather implausible.
dial side without date mechanism
The EB 8027 uses a rocking bar winding system, which is much cheaper than a
yoke winding system. Unfortunately, the click mechanism is also
very simple made - it consists only of one single spring, which blocks the ratched wheel. It's not
a solution for lifetime...
date mechanism
The date mechanism is, apart from one detail, pretty simple and genious at the same time:
The hour wheel drives the date setting wheel with a moveable fusee. This fusee tensions the date
setting lever during the whole day and reduces force from the movement. At midnight, the lever
can unblock in a single step, since the fusee is moveable, and advance the date.
The other function of the fusee is, that by setting the time back and forth a few hours, the
date can be corrected semi-fast.
The disadvantage of this construction are the two thin springs. They're breaking fast and so, don't
apply tension to the date setting wheel. Without tension, the whole mechanism is dead. You can
see the broken spring on the photo.
dial side view
The date ring is very broad. Unfortunately, it is made of plastic, which discolors by sun rays.
You can see, on which day, the date mechanism broke...
Technical data
Manufacturer
EB
Caliber
8027
Number of jewels
21
Escapement
pin lever
Balance
Nickel
Shock protection(s)
?
Balance cock direction
clockwise
Hairspring stud
moveable
Regulator type
Hairspring key
Movement construction
Fork Escapement wheel, Fourth wheel, Third wheel Center wheel Mainspring barrel
