We are well aware that it
takes lots of patient, hard study to master the complications of the
club-tooth lever escapement, but it is every watchmaker's duty to
conquer the problem. The definition of "lock," in the detached lever
escapement, is the stoppage or arrest of the escape wheel of a watch
while the balance is left free or detached to perform the greater
portion of its arc of vibration. "Draw" is a function of the locking
parts to preserve the fork in the proper position to receive and act on
the jewel pin of the balance.
It should be borne in mind in connection with "lock" and "draw," that
the line of thrust as projected from the locked tooth of the escape
wheel should be as near tangential as practicable. This maxim applies
particularly to the entrance pallet. We would beg to add that
practically it will make but little odds whether we plant the center of
our pallet staff at _C_ or _h_, Fig. 87, provided we modify the locking
and impulse angles of our pallets to conform to such pallet center.
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