The Escape Lever

The Horologium October 3, 2002 admin




JLC leverThe escape lever of a watch meters the
power of the gear train to the balance wheel and is thus a critical
component in any watch. The escapement of a watch operates at
extremely low forces and must do so with astonishing consistency
if the watch is to keep time.
For example, a few invisible droplets of oil
on many parts of the escapement can destroy the timing of the
watch because of adhesive forces or the drag of the (relatively)
high viscosity. Freedom from friction, alignment and stability
must be nearly perfect in the escapement of an excellent watch.
Thus finishing in these most critical components is critical
for performance, durability, and beauty.

The three escape levers are shown at 35
power magnification. The JLC escape lever (Figure 4A)
lives up to the expectations set by the rest of the watch. The
perfect polish of the steel and anglage (blue arrow) are
readily apparent, as is the excellent polish of the pivot (yellow
. Only very good steel will accept the deep black
polish apparent on this lever. The pallet jewels (red arrow)
are also perfectly set and aligned. It would be difficult to
improve on this execution.

Eterna escape leverBy comparison, the Eterna escape lever
(4B) looks relatively crude, though its finish is relatively
good by the standards of watches of this class. It is well formed,
of adequate rigidity, and shows good polish of the pivot. Its
surfaces are unpolished and without anglage. The Tissot escape lever (4C)
contrasts sharply with the other two. It is obviously a crude piece of
work, although its pivot is decently polished. (Any friction
in the balance pivots is likely to lower the amplitude of the
watch and may make reliable time-keeping impossible.) No effort
has been made to cosmetically dress this very small, largely
hidden part.

Tissot escape lever