An Analysis of the Lever Escapement

by H. R. Playtner

The dotted circle,

s s

, [Fig. 25], represents a single roller. It will be noticed that the corner of the crescent has passed the guard pin

u

by a considerable angle, and although this is so, in case of an accident the acting edge of the fork would come in contact with the ruby pin; this proves that a well made single roller escapement really requires but little horn, only enough to ensure the safe entry of the ruby pin in case the guard point at that moment be thrown against the roller. We will now examine the question from the standpoint of the double roller;

S2

, [Fig. 25], is the safety roller; the corner of the crescent has safely passed the dart

h

; the centers of the ruby pin

o