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 35 of 243 (14%)
page 35 of 243 (14%)
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and secure a perfectly sound escapement, with several claimed
advantages. Let us now take up the delineation of the exit pallet. It is very easy to locate the outer angle of this pallet, as this must be situated at the intersection of the addendum circle _i_ and the arc _g_, and located at _o_. It is also self-evident that the inner or locking angle must be situated at some point on the arc _h_. To determine this location we draw the line _B c_ from _B_ (the pallet center) through the intersection of the arc _h_ with the pitch circle _a_. Again, it follows as a self-evident fact, if the pallet we are dealing with was locked, that is, engaged with the tooth _D''_, the inner angle _n_ of the exit pallet would be one and a half degrees inside the pitch circle _a_. With the dividers set at 5", we sweep the short arc _b b_, and from the intersection of this arc with the line _B c_ we lay off ten degrees, and through the point so established, from _B_, we draw the line _B d_. Below the point of intersection of the line _B d_ with the short arc _b b_ we lay off one and a half degrees, and through the point thus established we draw the line _B e_. LOCATING THE INNER ANGLE OF THE EXIT PALLET. The intersection of the line _B e_ with the arc _h_, which we will term the point _n_, represents the location of the inner angle of the exit pallet. We have already explained how we located the position of the outer angle at _o_. We draw the line _n o_ and define the impulse face of the exit pallet. If we mentally analyze the problem in hand, we will see that as the exit pallet vibrates through its ten degrees of arc the |
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