Improvements in Electric Clocks.
Year: 1891

page_text: Date of Application, 13th Jan., 1891-Accepted, 21st Mar., 1891
COMPLETE SPECIFICATION.
Improvements in Electric Clocks.
I, EMIL GUSTAVUS HAMMER, of Number 122, Broadway, in the City of
Brooklyn, in the County of Kings and State of New York, United States of
America, Watchmaker, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement:
This invention relates to electric clocks, or those which are driven or wound by
means of electric energy.
My improved clock measures time through the action of any suitable escapement
which is driven by a spring that is wound at intervals by means of an electro-
magnet. The excitation of this magnet is determined by a circuit-closer which
closes the circuit at regular intervals of time, and is operated by the escapement.
The action of the magnet not only rewinds the escapement spring, but performs
the mechanical. work incident to the advancing of the hands or other indicating
devices of the clock to denote the time.
Fig. 1 of the accompanying drawings is a front elevation of my improved clock
on a small scale.
Fig. 2 is a front elevation of the dial mechanism thereof, partly broken away to
show the parts in the rear.
Fig. 3 is a front elevation of the driving and time-marking mechanism of the
clock, the dial mechanism being removed and the framework omitted.
Fig. 4 is a side elevation of the mechanism shown in Fig. 3, but including also
the supporting framework thereof:
Fig. 5 is an enlarged front elevation. Fig. 6 a vertical section, and Fig. 7 a plan
of the ratchet mechanism for rewinding the spring.
Fig. 8 is an enlarged front elevation of a fragment of Fig. 2, and Fig. 9 is a
horizontal section thereof.
Fig. 10 shows a part of the mechanism shown in Fig. 3, in connection with
circuit-closers for operating secondary electric clocks.
My improved clock will ordinarily be enclosed in an upright casing, such for
example as shown in Fig. 1. In addition to the usual clock-dial D having hour
and minute hands, the clock-casing is formed in its front with three openings,
through the upper one of which is exposed the number indicating hours, while
through the two lower openings are exposed the numbers indicating minutes. These
numbers are marked on three dials, A, B and C, shown in dotted lines in Fig. 1,
and in full in Fig. 2, (except that in the latter figure they are largely broken away
to show the parts behind them). The dial A is numbered from 0 to 9, and is turned
1of a revolution at the end of each minute. The dial B indicates tens of minutes
and is numbered from zero (blank) to 5, being turned from one number to the next
by the dial A while the latter is turning from 9 to 0. The dial C, which indicates
hours, is numbered from 1 to 12, and is turned of a revolution by the dial B each
time that the latter turns from 5 to blank.
The clocks shown in Figs. 1 and 2 has thus two distinct "time-indicating devices,"
one being the hour and minute hands on the dial D, and the other being the rotary
dials A B C, with the means for rotating them. Both these devices may be used in
the same clock, as shown, or either may be omitted.
Referring to Figs. 3 and 4, an electro-magnet E connected in a circuit & with a
battery F constitutes the motive device through which the entire clock is driven.
The armature E¹ of this magnet is mounted on an elbow-lever M having a prolonged
lateral arm on the end of which is carried an anti-friction roller which bears on the
long arm of a lever S, the opposite arm of which carries a counterweight w.
This

page_text: counterweight may constitute the retractile device for moving the armature away
from the magnet when the latter is demagnetized, or a separate retractile spring
may be provided, as shown.
The
Each time that the circuit is closed the magnet attracts its armature and throws
down the long arms of the levers M and S lifting the counterweight w.
lever S is connected through a rod j with a vibrating arm k carrying a pawl / which
engages the teeth of a ratchet-wheel m which is kept from turning backward by a
stop-pawl which is pivoted (Fig. 4), to one of the plates I of the supporting
frame. The ratchet-wheel m is fixed on the front portion of an arbor J, which
extends thence rearwardly and is fastened to the inner end of a coiled spring K,
which I will call the "escapement spring." The outer end of this spring is fastened
directly or indirectly to a gear-wheel L preferably by enclosing the spring in a
drum in the usual manner, fastening its end to the wall of the drum and forming
gear-teeth upon the periphery of the drum. In such case the drum turns loosely on
the arbor J, being turned solely by the tension of the coiled spring K. The gear L, to
which is thus imparted a tendency to turn in the direction of the arrow in Fig. 3,
meshes with a pinion n, also in Fig. 4. This pinion is fixed on a seconds arbor N,
which may carry the seconds hand N¹ (Figs. 1 and 4). The escapement may be
controlled by either a pendulum or a balance-wheel; the latter is shown. The
arbor N carries a wheel n¹ which meshes with a pinion on the arbor of the escape-
wheel Q, with which engages the anchor R, controlled in the usual way by the
balance-wheel P.
The electro-magnet E requires, in the construction shown, to be energized once
each minute, although other intervals of time might be selected. To do this it is
necessary to introduce in the circuit b some suitable form of circuit-closer which
shall be operated at intervals of one minute. Such a circuit-closer is shown in
Fig. 3.
Two very light levers T T¹ are gently pressed by delicate springs s¹¹
against stops t t¹, until the lower one is pressed up by a tooth on a cam-disk Ŭ fixed
on the seconds arbor N, whereupon it touches the upper one and they lift together
until the tooth passes beyond the end of the lower lever. Both levers are connected
in the circuit b, so that this circuit is normally open, and is closed once each minute
when the levers are brought together by the cam-tooth. The closing of the circuit
excites the magnet and throws down the long arm of the levers M and S, thereby
causing the pawl to move down over one tooth of the ratchet-wheel m. Upon the
breaking of the circuit the armature is retracted and the lever S is tilted by its
weight w to the position shown in full lines, thus pulling up the link and arm k
and causing the pawl to advance the ratchet wheel m the distance of one tooth.
The consequent turning of the arbor J winds up the spring E to the corresponding
extent.
The proportions of the respective parts are such that by the action of the pawl
and ratchet the spring K is wound up at each excitation of the magnet as much as
it has run down by the rotation of the gear L in turning the pinion n and seconds
arbor one revolution. Thus at the end of each minute the spring is wound up as
much as it has run down during such minute, so that it is restored to its original
tension. The winding up of the spring K is effected directly by the tension of the
counterweight w when this counterweight is released by the reaction of the armature,
so that the tension applied to the ratchet and pawl is always uniform and indepen-
dent of the strength of the battery so that no possible derangement can result from
the varying energy with which the magnet may be excited at different times.
I will now explain how the dial mechanism shown in Fig. 2 is driven.
The lever S carries an arm or finger a which upon the release of the armature
and the return of the lever by the action of the counterweight moves down against
the bearing face a¹ on a lever G, thereby tilting this lever and causing a pawl G
which it carries to strike one of the teeth of a ratchet-wheel A' fixed to the spindle
of the disk A and turn the latter of a revolution. Before turning it, however,
the pawl G' acts on the inclined end or toe d of an elbow-lever e the other arm of
which carries a locking-tooth H. The pawl acts first to press back the toe d,

page_text: thereby lifting the lock H out of one of the notches in a locking-disk H', to the
position shown in full lines in Fig. 8; it then holds the lever e and lock H in this
position while it turns the ratchet-wheel A¹, and until it reaches the position shown
in dotted lines in Fig. 8, the notch having thus been moved beyond the bolt to the
position shown at c, whereupon the pawl releases the toe and permits the lock to
drop into the disk H', ready to fall into the next notch; and the pawl continues to
move down until it reaches the position shown in dotted lines in Fig. 2, having thus
advanced the ratchet A' the distance of one tooth. At the completion of an
entire revolution of the disk A, that is to say, while it is turning from 9 to 0, an
arm which it carries encounters a pin or projection f¹ fixed to and projecting
rearwardly from the disk B, and turns the latter one space so as to cause it to
display the next higher number. First, however, the disk B is unlocked by
releasing a lock B₁ having a notch which engages one of the pins f1 thereof. This
lock B is carried on a lever g which is tilted by the action of a pin g³ carried by
the disk H¹ on a tooth connected through a rod with the lever 9. As the
disk B turns from 5 to blank (or zero) an arm h which it carries strikes a pin " on
a disk C' fixed on the arbor of the disk C and turns the latter of a revolution.
First, however, the disk C is unlocked by withdrawing a lock C" which engages
one of the pins thereof. This lock C is mounted on a lever at which is tilted
by a pin carried with the disk B acting on a tooth y' on a rod g connected to
this lever.
11
When a clock has both the numbered disks A, B and C, and the dial D with its
hands, the latter are turned by the mechanism shown in the upper part of Fig. 2.
A rod i pivoted to the lever G at its lower end communicates motion to a smaller
lever V above. The pawl V₁ of this lever acts in the teeth of a ratchet-wheel W
fixed on the minute hand arbor. A notched disk Y, also fixed on this arbor, is
locked by a lock Y¹ mounted on an elbow-lever e', the lower arm of which has a
cam surface or toe d' which is displaced by the end of the pawl V1 before it com-
mences to move the wheel W. The operation is the same as the lock H with the
disk H' already described. The motion is communicated to the hour hand through
the usual wheels y y.
In lieu of operating the ratchet in by a pawl 1 on an arm as shown in Fig. 3, I
prefer to employ the construction shown in Figs. 5, 6 and 7. The ratchet m has
peripheral teeth engaged by the locking-pawl, and in addition is formed with
crown ratchet teeth m' which are engaged by similar crown ratchet teeth m² formed
on a disk pivoted on the arbor J and pressed toward the ratchet m by a leaf-
spring. The disk is oscillated forward and back by the rod j which is guided
to an arm ¹ formed on this disk. As the arm is moved upwardly, the teeth m²
propel the ratchet m forward, and as the arm is moved downwardly, the teeth m*
ride over the teeth m', the spring pressing them backwardly into engagement
with the next successive teeth. The disk with its teeth m* constitutes sub-
stantially a pawl.
By my improved construction of clock the time-measuring mechanism is reduced
to the utmost simplicity, consisting only of the escapement, its impelling spring and
their connecting gear and pinion. The liability of derangement is consequently
reduced to the minimum so that with proper workmanship the clock should run for
years without attention. So long as the mechanism remains in order the clock will
continue to run as long as the battery supplies the necessary energy. By reason
of the very frequent rewinding of the spring K it is kept always at uniform tension
so that the impulse of the escapement on the balance wheel is unvarying. The
energy required to be transmitted through the spring is reduced to the minimum, so
that a light spring may be used. The electro-magnet at each operation thus stores
up the power required for driving the time-measuring mechanism by which it is
governed, and also exerts the power necessary to drive the time-indicating
mechanism. The time-measuring mechanism is thus entirely relieved of the work
of driving the time-indicating mechanism, so that the clock is rendered a very
accurate time-keeper. This sub-division of the work is especially desirable in a

page_text: clock, wherein the, time-indicating device consists of a combination of dials, since
the driving of such device requires different amounts of power at different, times,
requiring the least power when only the disk A. is being driven, requiring greater
power when, the disks A and B, turn simultaneously, and, still greater power at
intervals of an hour when the disks A, B and C turn, all together.
By the construction of the magnetic winding apparatus with an armature lever.M
with its long arm bearing on the long arm of a counterweighted lever S, and the
latter connected to a swinging arm k for moving the pawl (1 or 1) a long sweep is
secured, and the pawl enabled to propel the ratchet far enough at each vibration to
wind up the spring sufficiently so that only a single gear and pinion is required to
communicate movement to the seconds arbor, and the latter is propelled for an
entire revolution before the spring requires rewinding. Otherwise it would be
necessary to close the circuit oftener than once a minute, or to interpose more
wheels to gear up sufficiently to the seconds arbor.
My improved clock may be used as a primary electric clock for controlling the
movements of secondary electric clocks. This may be done as shown in Fig. 10,
where the lever S is connected in the circuit of a battery F and at each
vibration makes contact with levers, thereby closing circuits y y leading to
distant secondary clocks X X. These secondary clocks are of any usual con-
struction. When the lever S vibrates back to its normal position, the contact
levers are drawn by their springs against screw-stops uu. By adding
more levers h the same clock may be used to operate a greater number of
circuits, or additional secondary clocks may be introduced in the same circuits q
My improved electric clock may be used as a secondary clock by omitting the
time-measuring mechanism, including the escapement and escapement-spring, and
the means for winding the latter, and by connecting the electro-magnet M in circuit
with a primary, clock which shall close the circuit once a minute or at other
intervals. The lever S then acts through the arm a upon the lever G only to
operate the time-indicating mechanisın.
.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. In an electric clock the utilization of an electro-magnet to actuate the time-
indicating mechanism and also to wind up the spring of an escapement, the magnet
being controlled by a circuit-closer operated by the escapement, whereby the sole
work of the escapement spring is to drive the escapement and circuit-closer, and the
heavier or varying work of driving the indicating device is performed by the
electro-magnet, substantially as set forth.
2. In a clock, an electro-magnet E operating an armature-lever M the long arm
of which engages a counterweighted lever S, which communicates motion to a
pawl and thereby propels a ratchet-wheel m, and the spring of an escapement
connected to the arbor of said ratchet-wheel to be wound up by the latter at the
same rate at which it runs down in propelling the escapement..
3. In a clock wherein numbered dials (as A, B and C) are employed for
indicating the time, the employment of an electro-magnet to actuate a counter-
weighted lever S which has an arm a for imparting motion to the driving
mechanism of the dials, said magnet being controlled by a circuit-closer operated
by an escapement the spring of which is wound from said lever S through a pawl
and ratchet.
4. In an electric clock, a circuit-closer consisting of two contact-levers T and T',
seating against stops tt', and one pressed against the other to close the circuit by a
rotary cam U.
5. In an electric clock wherein the escapement-spring is wound by an electro-
magnet acting through a pawl and ratchet, the construction of the pawl with crown
ratchet-teeth in² engaging crown teeth m' on the ratchet, and pressed against it by
a spring, substantially as shown in Figs. 5, 6 and 7.

page_text: 6. In an electric clock, a lock (as H) for locking a disk (as H¹,) operated by a
lever e having an inclined toe d which is pressed to one side by a pawl G₁ on
an operating arm G before the engagement of said pawl with the tooth of a ratchet-
wheel A' for actuating a time-indicating device substantially as shown in Figs. 2, 8
and 9.
נים
1001
J. C. MEWBURN,
55 and 56, Chancery Lane, London, Patent Agent.