Technology and Function
of the Mechanica M
2
74
75
Discharge
The balance
*
comes from its left complementary arc and oscillates
counterclockwise. Shortly before Dead center
*
, the Impulse pallet
*
engages the pallet fork and takes the pallet lever with it for a bit
(discharge
*
).
Lift (impulse)
When the balance oscillates counter
-
clockwise and approaches Dead center
*
,
the escape wheel glides from the Locking
plane of the entry pallet to the slanted
impulse plane. The entry pallet is then
pushed upward (lifted), moving the shaft
of the pallet lever and guiding the pallet
fork to the right. Using the motion of the
pallet fork (impulse), during its short
rotation the escape wheel transmits
the impulse energy from the Spring barrel
*
and the Gear train
*
to the pallet
*
fork
and
further accelerates the balance
*
in
a
counterclockwise direction via the
impulse pin.
Drop
Together with the impulse, the exit pallet drops
the short rotation of the escape wheel into the
radius of the escape wheel teeth and guides
the pallet fork to the right until it hits the
banking stud. The escape wheel is once again
obstructed after the short rotation. The Semi-
oscillation with its complete cycle of events
(discharge-lift-drop) is thus complete.
The balance now oscillates further to the right
inversion point, changes its rotational direction
there, and then completes the next cycle in
a clockwise direction during the next semi-
oscillation.
Commenting the Individual Sequence of Movements
The sequence of movements described here take place during every
Semi-oscillation of the balance, which alternately goes through Dead
center
*
from the left and the right.
Let’s Begin with the Lift
The lift
*
is one of the most important functions of the escape-
ment. During the lift the balance
*
receives the energy necessary
to maintain the oscillation. This occurs when the escape wheel
glides across the impulse plane of a pallet
*
. At this point, the
pallet lever, which engages the Impulse pallet
*
of the balance
near Dead center via the pallet fork, is put into motion. In the
Swiss Club-tooth Lever escapement
*
used here, the lift is
achieved both through the pallet of the pallet lever and the
escape wheel tooth itself.
After the Lift Comes the Drop
The drop
*
is the free rotational motion of the escape wheel, after
which the escape wheel tooth is dropped from the pallet. It
represents a big point of security necessary to maintain the
functioning of the escapement. This means, it allows the pallet
to plunge back into the toothed wheel of the escape wheel
during the next Semi-oscillation without touching down on the
back of the tooth. In order to guarantee the largest possible
functionality, the drop of both pallets needs to be the same.
After the escape wheel tooth drops onto a pallet, another
escape wheel tooth drops onto the Locking plane
*
of another
pallet. In this moment, the escape wheel stands still and the Gear train
*
is blocked. The escapement thus fulfills its second important task.
The Last Term to be Explained is Locking
The locking motion is also important for the secure functioning.
Locking can be described as the small distance located on the
Locking plane
*
of the pallet, which the escape wheel tooth
traverses from the moment it touches down on the Locking
plane until it glides onto the lifting plane. This small surface is
only a fraction of a millimeter, and it prevents the escape wheel
tooth from directly touching down on the lifting plane, thus
preventing the balance from oscillating further.
Drop
Lock
