Technology and Function
of the Mechanica M
2
64
65
In classic watchmaking two basic styles of regulating
*
organs are used:
◊
The pendulum
*
in grandfather clocks, wall or tower clocks, and
pendulum clocks
and
◊
the balance spring
*
and balance
*
for pocket and wristwatches
and table clocks
The first classic mechanical escapement for timepieces was the
pendulum
*
discovered by Galileo Galilei
*
in 1585. With its regular
oscillations, it aided timekeeping to a decisive breakthrough.
According to Galileo’s observations, a pendulum
*
swings contem-
poraneously regardless of its amplitude
*
of oscillation. The frequency
is determined alone by the length of the pendulum under ideal
conditions. The balance system differentiates itself from the
pendulum in that it is gravity that is effectively the pendulum’s
returning energy. The balance system, on the other hand, uses elastic
deformation energy of the balance spring
*
as its return. The
amplitude
*
of the pendulum amounts to just a few minutes of arc,
while the balance generally has an amplitude between 200 and 300
degrees depending on the design and use (pocket watch,
wristwatch, or table clock).
The escapement
*
—comprising balance
*
, pallet
*
lever, and escape
wheel
*
—builds the heart of every timekeeper and is responsible for
the typical ticking sound a mechanical timepiece makes. It is based
on a mechanical oscillating system to portion the time, which divides
it into precisely defined sections. The length of an oscillation is
determined by the reciprocal effect of the mass-spring system in
conjunction with the (mass) inertia of the balance
*
and the return
energy of the balance spring
*
. The escapement alone does not a
movement make, however. Additionally, the oscillation of the
balance must be transmitted to the Gear train
*
and, reciprocally, the
motive energy from the Gear train to the balance. These tasks are
undertaken by the escapement
*
. In addition, the Spring barrel
*
with
its mainspring
*
and the Gear train also play an important role so that
the balance oscillates evenly, or isochronously as we say today. Finally,
the time portions determined by the escapement have to be translated
into minutes and hours via the Dial train
*
and displayed on a dial.
Your Mechanica M2 is outfitted with a classic Swiss lever
escapement
*
beating at a frequency of 18,000 semi-oscillations per
hour (2.5 Hertz).
The Balance Spring
Caution:
Please be careful
when handling the
escapement, making
sure that the
sensitive balance,
and the filigreed
escape wheel are
not touched or
damaged!
The Escapement*
The invention of the balance spring for
mechanical timepieces can be attributed to
Christiaan Huygens
*
, who invented the
Archimedian spring in 1675. Subsequently,
generations of watchmakers have
consistently attempted to have the balance
*
oscillate evenly or isochronously (isochron
is Greek for »same in time«). Significant
improvements were made again and again by
making the spring more filigreed and lighter over the
course of centuries. The length of the balance spring
*
(number of
turns or coils) was chosen in relation to the weight and moment
of inertia of the balance, and the resulting elasticity is determined by
the so-called Pinning point
*
of the balance spring collet
*
. The
diameter of the balance spring is normally between one-half and
two-thirds of the diameter of the balance. The inside end of the
balance spring is secured to a pressed collet on the balance staff. The
outer end of the balance spring is bent into a so-called Terminal
curve
*
and secured to the pallet cock via the balance spring stud
*
on
the Stud carrier
*
.
If the balance wheel is moved from its position in either direction, the
elastic balance spring deforms and stretches—the more it does so,
the bigger the rotational angle of the displacement. When the
balance is then let go, it oscillates through the elastic force of the
deformed balance spring back to Dead center, where the balance’s
speed is the greatest. The oscillating energy allows the balance to
rotate, but back across the other side of Dead center
*
to a practical-
ly identical angle on the other side—similar to the swing of a
pendulum
*
. Without the braking effect of friction
*
, these oscillations
would remain infinitely long. In order to compensate for the reality of
friction, the balance—as we explain later—must be driven.
Spiralrolle
Spiralklötzchen
