Watch and Clock Escapements - A Complete Study in Theory and Practice of the Lever, Cylinder and Chronometer Escapements, Together with a Brief Account of the Origin and Evolution of the Escapement in Horology by Anonymous
page 33 of 243 (13%)
page 33 of 243 (13%)
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between its intersection with the line _B j_ and the center _A_, and
from _A_ as a center sweep the arc _i_, said arc defining the _addendum_ of the escape-wheel teeth. We draw a line from the intersection of the radial line _A f_ with the arc _i_ to the intersection of the radial line _A g_ with the arc _a_, and thus define the impulse face of the escape-wheel tooth _D_. For defining the locking face of the tooth we draw a line at an angle of twenty-four degrees to the line _A g_, as previously described. The back of the tooth is defined with a curve swept from some point on the addendum circle _i_, such as our judgment will dictate. In the drawing shown at Fig. 20 the radius of this curve was obtained by taking eleven and a half degrees from the degree arc of 5" radius in the dividers, and setting one leg at the intersection of the radial line _A f_ with the arc _i_, and placing the other on the line _i_, and allowing the point so established to serve as a center, the arc was swept for the back of the tooth, the small circle at _n_ denoting one of the centers just described. The length for the face of the tooth was obtained by taking eleven degrees from the degree arc just referred to and laying that space off on the line _p_, which defined the face of the tooth. The line _B k_ is laid off one and a half degrees below _B h_ on the arc _m_. The extent of this arc on the arc _d_ defines the locking face of the entrance pallet. We set off four degrees on the arc _m_ below the line _B k_, and through the point so established draw the line _B l_. We draw a line from the intersection of the line _A g_ with the line _c h_ to the intersection of the arc _e_ with the line _c l_, and define the impulse face of the entrance pallet. RELATIONS OF THE SEVERAL PARTS. |
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