An Analysis of the Lever Escapement

by H. R. Playtner

The space between the discharging edge

P

and the heel of the tooth forms the angle of drop

J B I

of 1½°; the definition for drop is that it is the freedom for wheel and pallet. This is not, strictly speaking, perfectly correct, as, during the unlocking action there will be a recoil of the wheel to the extent of the draft angle; the heel of the tooth will therefore approach the edge

P

, and the discharging side of the pallet approaches the tooth, as only the discharging edge moves on the path

P

.

A good length for the teeth is ¹⁄₁₀ the diameter of the wheel, measured from the primitive diameter and from the locking edge of the tooth.