This would have placed the center of the
pallet staff farther in, or closer to the wheel. Any person can see at a
glance that the pallets as delineated are not tangential in a true
sense.
[Illustration: Fig. 85]
We have previously considered engaging friction and also repeatedly have
spoken of tangential lockings, but will repeat the idea of tangential
lockings at Fig. 85. A tangential locking is neutral, or nearly so, as
regards engaging friction. For illustration we refer to Fig. 85, where
_A_ represents the center of an escape wheel. We draw the radial lines
_A y_ and _A z_ so that they embrace sixty degrees of the arcs _s_ or
_t_, which correspond to similar circles in Fig. 84, and represent the
extreme extent of the teeth and likewise the locking angle of such
teeth. In fact, with the club-tooth escapement all that part of a tooth
which extends beyond the line _s_ should be considered the same as the
addendum in gear wheels. Consequently, a tangential locking made to
coincide with the center of the impulse plane, as recommended by
Saunier, would require the pallet staff to be located at _C'_ instead of
_C_, as he draws it.
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