The extent of the space
between the lines _A l'_ and _A m'_ on the circle _a_ defines the size
of our jewel pin.
TO DETERMINE THE SIZE OF A JEWEL PIN.
[Illustration: Fig. 56]
To make the situation better understood, we make an enlarged drawing of
the lines defining the jewel pin at Fig. 56. At the intersection of the
line _A B_ with the arc _a_ we locate the point _k_, and from it as a
center we sweep the circle _i_ so it passes through the intersection of
the lines _A l'_ and _A m'_ with the arc _a_. We divide the radius of
the circle _i_ on the line _A B_ into five equal parts, as shown by the
vertical lines _j_. Of these five spaces we assume three as the extent
of the jewel pin, cutting away that portion to the right of the heavy
vertical line at _k_.
[Illustration: Fig. 57]
We will now proceed to delineate a fork and roller as the parts are
related on first contact of jewel pin with fork and initial with the
commencing of the act of unlocking a pallet. The position and relations
are also the same as at the close of the act of impulse.
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