GRAHAM ESCAPEMENT:
The dead beat escapement also known as the graham escapement is
characterized by its action of lock and slide ad it operates. This type of system
can be easily recognized by looking at the verge. Pay particular attention to the
working faces of the verge, there will be a flat edge where the escape wheel tooth
hits upon releasing from the opposite side and a sharp edge that the tooth drops off
from the flat part and an angled surface that the tooth slides along as it gives the
pendulum an extra push until it lets go and the whole thing starts again on the other
side. This type of system is or can be quite accurate because the verge has significant
control over how much power is delivered to the pendulum. If however there is too much lock or not enough lock the accuracy and dependability will be questionable
at best. The depth setting is not the same for all clocks although the principle is the
same. Generally speaking weight drive clocks with heavy pendulums are more
sensitive and require somewhat shallow depth settings keeping in mind not to
completely eliminate the lock segment of the operation.
The following is a list of some of the sensitive clocks:
seth thomas #2 regulators , most vienna regulators
most french clocks
jewelers regulators (large wall clocks and floor clocks with mercury filled pendulums)