Part 2 (2/2)

[Illustration: Fig 20]

We again lay off two and a half degrees from the intersection of the line _A b_ with the arc _a_, but this tih the point so established, and from _B_ as a center, eep the arc _e_ Fro_ with the arc _a_ we lay off to the left five and a half degrees on said arc, and through the point so established draw the radial line _A f_

With the dividers set at five inches eep the short arc _m_ from _B_ as a center From the intersection of the line _h B h'_ with the arc _m_ we lay off on said arc and above the line _h'_ four and a half degrees, and through the point so established draw the line _B j_

We next set the dividers so they embrace the space on the radial line _A b_ between its intersection with the line _B j_ and the center _A_, and fro 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 i 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 fro 20 the radius of this curve was obtained by taking eleven and a half degrees fro 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 ept for the back of the tooth, the s one of the centers just described The length for the face of the tooth was obtained by taking eleven degrees fro 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 _ face of the entrance pallet We set off four degrees on the arc _h the point so established draw the line _B l_ We draw a line fro_ 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

Before we proceed to delineate the exit pallet of our escapement, let us reason on the relations of the several parts

The club-tooth lever escapement is really the most complicated escapement made We mean by this that there areit correctly than in any other known escapement Most--we had better say all, for there are no exceptions which occur to us--writers on the lever escape the several parts, without giving reasons for this or that course For illustration, it is an established practice as, as we explained and illustrated in Fig 16

Noe adopt circular pallets and carry the locking face of the entrance pallet around to the left two and a half degrees, the true center for the pallet staff, if we eent to the circle _a a_ fro 21 Such a tangent is depicted at the line _s l'_ If we reason on the situation, ill see that the line _A k_ is not at right angles to the line _s l_; and, consequently, the locking face of the entrance pallet _E_ has not really the twelve-degree lock we are taught to believe it has

[Illustration: Fig 21]

We will not discuss these minor points further at present, but leave them for subsequent consideration We will say, however, that we could locate the center of the pallet action at the small circle _B'_ above the center _B_, which we have selected as our fork-and-pallet action, and secure a perfectly sound escapees

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 addendu_, 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_ froh 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 as 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”, eep 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 ill terle of the exit pallet We have already explained hoe 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 probleh its ten degrees of arc the line _B d_ and _B c_ change places, and the tooth _D''_ locks one and a half degrees To delineate the locking face of the exit pallet, we erect a perpendicular to the line _B e_ from the point _n_, as shown by the line _n p_

From _n_ as a center eep the short arc _t t_, and frorees, and through the point so established we draw the line _n u_, which defines the locking face of the exit pallet We draw the line _o o'_ parallel with _n u_ and define the outer face of said pallet In Fig 21 we have not made any attempt to show the full outline of the pallets, as they are delineated in precisely the same manner as those previously shown

We shall next describe the delineation of a club-tooth escape 22 we shall show pallets with much wider arms, because, in this instance, we shall derive more of the impulse from the pallets than froical student the facility hich the club-tooth lever escapement can be manipulated We wish also to impress on his mind the facts that the employment of thick pallet arms and thin pallet arms depends on the teeth of the escape wheel for its efficiency, and that he h of the principles of action to tell at a glance on what lines the escapeet hold of a watch which has thin pallet arms, or stones, if they are exposed pallets, and the escape was designed for pallets with thick arive such a watch a good e either the escape wheel or the pallets If we know enough of the lever escapehts; but othere can look and squint, open and close the bankings, and tinker about till doomsday, and the watch be none the better

CLUB-TOOTH LEVER WITH EQUIDISTANT LOCKING FACES

In drawing a club-tooth lever escape, we co the vertical line _A k_, Fig 22, and establishi+ng the center of the escape wheel at _A_, and with the dividers set at 5” sweep the pitch circle _a_ On each side of the intersection of the vertical line _A k_ with the arc _a_ we set off thirty degrees on said arc, and through the points so established draw the radial lines _A b_ and _A c_

From the intersection of the radial line _A b_ with the arc _a_ lay off three and a half degrees to the left of said intersection on the arc _a_, and through the point so established draw the radial line _A e_

From the intersection of the radial line _A b_ with the arc _a_ erect the perpendicular line _f_, and at the crossing or intersection of said line with the vertical line _A k_ establish the center of the pallet staff, as indicated by the small circle _B_ From _B_ as a center sweep the short arc _l_ with a 5” radius; and from the intersection of the radial line _A b_ with the arc _a_ continue the line _f_ until it crosses the short arc _l_, as shown at _f'_ Lay off one and a half degrees on the arc _l_ below its intersection with the line _f'_, and froh said intersection

Froh the intersection of the radial line _A b_ and the arc _a_, sweep the arc _g_

The space between the lines _B f'_ and _B i_ on the arc _g_ defines the extent of the locking face of the entrance pallet _C_ The intersection of the line _B f'_ with the arc _g_ we denominate the point _o_, and from this point as a center sweep the short arc _p_ with a 5” radius; and on this arc, from its intersection with the radial line _A b_, lay off twelve degrees, and through the point so established, from _o_ as a center, draw the radial line _oface of the entrance pallet _C_