An Analysis of the Lever Escapement | Page 7

point. In the case of the disengaging pallet, PP illustrates the path
of the discharging edge; the loss is measured as in the preceding case
where GH is intersected as shown by AD2. It amounts to a different
value on each pallet. Notice the loss between C and C2, on the
engaging, and D and D2 on the disengaging pallet; it is greater on the
engaging pallet, so much so that it amounts to 2°, which is equal to the
entire lock; therefore if 8½° of work is to be accomplished through this
pallet, the lifting plane requires an angle of 10½° struck from AC.
Let us now consider the lifting action of the club tooth wheel. This is
decidedly a complicated action, and requires some study to
comprehend. In action with the engaging pallet the wheel moves up, or
in the direction of the motion of the pallets, but on the disengaging
pallet it moves down, and in a direction opposite to the pallets, and the
heel of the tooth moves with greater velocity than the locking edge;
also in the case of the engaging pallet, the locking edge moves with
greater velocity than the discharging edge; in the disengaging pallet the

opposite is the case, as the discharging edge moves with greater
velocity than the locking. These points involve factors which must be
considered, and the drafting of a correct action is of paramount
importance; we therefore show the lift as it is accomplished in four
different stages in a good action. Fig. 9 illustrates the engaging, and
Fig. 10 the disengaging pallet; by comparing the figures it will be
noticed that the lift takes place on the point of the tooth similar to the
English, until the discharging edge of the pallet has been passed, when
the heel gradually comes into play on the engaging, but more quickly
on the disengaging pallet.
We will also notice that during the first part of the lift the tooth moves
faster along the engaging lifting plane than on the disengaging; on
pallets 2 and 3 this difference is quite large; towards the latter part of
the lift the action becomes quicker on the disengaging pallet and slower
on the engaging.
To obviate this difficulty some fine watches, notably those of A. Lange
& Sons, have convex lifting planes on the engaging and concave on the
disengaging pallets; the lifting planes on the teeth are also curved. See
Fig. 11. This is decidedly an ingenious arrangement, and is in strict
accordance with scientific investigation. We should see many fine
watches made with such escapements if the means for producing them
could fully satisfy the requirements of the scientific principles
involved.
[Illustration: Fig. 9.]
The distribution of the lift on tooth and pallet is a very important matter;
the lifting angle on the tooth must be less in proportion to its width than
it is on the pallet. For the sake of making it perfectly plain, we illustrate
what should not be made; if we have 10½° for width of tooth and pallet,
and take half of it for a tooth, and the other half for the pallet, making
each of them 5¼° in width, and suppose we have a lifting of 8½° to
distribute between them, by allowing 4¼° on each, the lift would take
place as shown in Fig. 12, which is a very unfavorable action. The edge
of the engaging pallet scrapes on the lifting plane of the tooth, yet it is
astonishing to find some otherwise very fine watches being

manufactured right along which contain this fault; such watches can be
stopped with the ruby pin in the fork and the engaging pallet in action,
nor would they start when run down as soon as the crown is touched,
no matter how well they were finished and fitted.
[Illustration: Fig. 10.]
The lever lengths of the club tooth are variable, while with the ratchet
they are constant, which is in its favor; in the latter it would always be
as SB, Fig. 13. This is a shorter lever than QB, consequently more
powerful, although the greater velocity is at Q, which only comes into
action after the inertia of wheel and pallets has been overcome, and
when the greatest momentum during contact is reached. SB is the
primitive radius of the club tooth wheel, but both primitive and real
radius of the ratchet wheel. The distance of centers of wheel and pallet
will be alike in both cases; also the lockings will be the same distance
apart on both pallets; therefore, when horologists, even if they have
worldwide reputations, claim that the club tooth has an advantage over
the ratchet because it begins the lift with a shorter lever than the latter,
it does not make it so. We are