IMPROVEMENTS IN ELECTRIC CLOCKS
Year: 1885

page_text: "
I, HERMANN ARON, Dr Philos. of 8 Genthiner Strasse, Berlin, in the Kingdom
of Prussia, German Empire, do hereby declare the nature of my Invention for
IMPROVEMENTS IN ELECTRIC CLOCKS; to be as follows:-
My Invention relates to improvements in electric clocks, and it consists in the
arrangement of an electro-magnet in combination with an armature connected to a
lever arm, the movements of which serve to give a regular impulse to the pendulum
of the clock as well as to impart motion to the dial train, and also to close and
interrupt, at the exact period required, the circuit within which the electro-magnet
is enclosed, thus causing the armature to be attracted and released in regular
adjustable intervals. The expense of electric force in this construction of my
Invention is reduced to a minimum, and by elastic cushions which are provided to
intercept the shock of the parts striking against each other, I further obtain, that
the motion of this clock is perfectly silent.
In combination with a train of clock-work of any suitable construction, I arrange
an electro-magnet enclosed within the circuit of a suitable couple. In proximity to
the projecting cores of the said electro-magnet, an armature is secured to an arin.
of a lever pivoted in such a manner as to allow to the said armature a motion
towards and from the electro-magnet. The said lever is provided with suitable
means to impart motion to the dial-train and also to give impulse to the pendulum.
While the clock-work is stopping, the circuit of the couple is interrupted, and
the armature rests on or in close proximity to the electro-magnet. To make the
clock go, I give the pendulum an impulse towards the lever, thereby causing the
lever-arm which carries the armature to be lifted. On the return of the pendulum
the lever also will fall under the influence of gravitation, and at the moment when
the armature has again nearly reached the cores of the electro-magnet, the circuit
of the couple is closed by a contact worked by the motion of the lever. At that
moment the armature will be attracted, and as the said armature is attached to an
arm of the swinging lever, the latter receives a sudden impulse, which at the same
time serves to impel the pendulum and to advance the dial train. During the
remaining part of its motion the pendulum continues to swing freely, and on its
return strikes again against the lever, which thereby is lifted as before and in its
following downward motion works a new contact, gives a fresh impulse to the
pendulum and imparts further motion to the dial train. In this manner the clock-
work continues to go for such length of time, as the couple will render sufficient
force to excite the electro-magnet.

page_text: An essential feature of my Invention is the device to close and to interrupt the
circuit of the couple at the exact period required, for the purpose of effecting an
alternate attraction and release of the armature by the electro-magnet. This device
consists of two little levers enclosed in the circuit of the couple, and arranged in such
proximity to each other, that when the one of said little levers is lifted by the
downward motion of the main or armature lever, it enters into contact with the
other little lever, thereby closing the circuit. The contact is however immediately
broken again, even before the attracted armature actually strikes upon the cores of
the electro-magnet, and owing to such release, the armature will at once become
free to be lifted again by the next stroke of the pendulum.
By a suitable arrangement of the two little contact-levers towards each other I
obtain a sliding contact, which secures a perfect and regular action of said contact.
It is of great importance that contact be made between the two little levers at
the time where the armature during its descent towards the magnet is in close
proximity to the same; by this means the momentary attraction by which fresh
impulse is given to the pendulum and motion imparted to the dial train, will be
worked with an exceedingly small expense of electric force. To obtain a perfectly
regular motion of the clockwork, it is further important to reduce the gravitation
of the lever-arm to which the armature is connected, to a moderate extent; for
this purpose the main or armature lever may be provided with adjustable counter-
weights, or the parts of said lever may be arranged to balance each other as much
as required.
To avoid the sparks at the places where contact is made, which sparks use to
oxydise the metal, I provide a particular construction of the coils of the electro-
magnet. Said sparks are known to be called forth by induced currents which arise
by the interruptions of the main current. To do away as much as possible with such
induced currents, I provide between every two windings of the coils of the electro-
magnet a cylindric sheet of conducting metal, and I also make the shells of the
coils of such metal, preferably of copper. These shells and sheets between the
wire coils so much absorb the reciprocal induction of the parts, that induced
currents scarcely arise in the wire coils, and that accordingly scarcely any sparks
are called forth where contact is made.
To intercept the stroke of metal parts against each other in this construction of
an electric clock, and to secure a perfectly silent motion of the same, I provide
elastic cushions between the respective parts. Such cushions, preferably of rubber,
are arranged between the armature and the cores of the electro-magnet, as also
between the pendulum and that part of the main or armature lever which bears
against the pendulum, and finally between the little contact lever and the screw
upon which it is to strike.

page_text: I HERMANN ARON Dr Philos. of 8 Genthiner Strasse Berlin in the Kingdom of
Prussia German Empire do hereby declare the nature of my said invention for
"IMPROVEMENTS IN ELECTRIC CLOCKS," and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
My invention relates to improvements in electric clocks and it consists in the
arrangement of an electro magnet in combination with an armature connected to a
lever arm the movements of which serve to give a regular impulse to the pendulum
of the clock as also to impart motion to the dial train and further to close and
interrupt at the exact period required the circuit within which the electro-magnet
is enclosed, thus causing the armature to be attracted and set free in regular
adjustable intervals. The expense of electric force in this construction of my
invention is reduced to a minimum and by elastic cushions which are provided to
intercept the shock of the parts striking against each other. I further obtain the
advantage that the motion of this clock is perfectly silent.
With reference to the drawings which forin part of this specification Fig. 1 is a
front elevation of an electric clock-work fitted with the improvements of my
invention, the lower part of the pendulum being broken away and the dial shown
in dotted lines. Fig. 2 is a side elevation of the clock-work, and Fig 3 an end
clevation of the parts constituting the improvements of my invention, the lower
part of the electro magnet being broken away Fig. 4 and 5 are detail views
hereinafter referred to, and Figs 6 and 7 show modifications of one part of my
invention.
In combination with a train of clock-work of any suitable construction I arrange
an electro magnet A carried by a suitable bracket or brackets and enclosed within
the circuit of a suitable battery P as shown in Fig. 3. In proximity to the pro-
jecting cores of the said electro magnet A an armature B is secured to an arm C¹
of bell-crank lever pivoted at C2 in a manner to allow to the said armature a
motion towards and from the electro magnet in the longitudinal direction of its
cores. The vertical arm C of the said bell crank lever is provided with an arm
carrying an elastic blade F catching as a pawl into the teeth of a little ratchet
wheel H by which motion is imparted to the dial train. To the lower end of the
said lever arm C¹ a pin G is secured bearing against the side of the pendulum E.
In the position shown in the drawings the armature B rests on the cores of the
electro magnet A. On giving to the pendulum E a slight impulse to the left of
Fig 3. the lever C resting with its pin G against the side of the pendulum will be
caused to move in the same direction, and the lever arm C¹ with the armature B
will be lifted from the electro-magnet. The blade or pawl F during this movement
slides over one tooth of the little wheel H and catches into the next indentation.
While lifting the armature B from the magnet A the circuit of the battery P is
interrupted. In the return motion of the lever C the armature B will again come
near the magnet and the blade or pawl F will turn the wheel H by one tooth. At
that moment the circuit will be closed and accordingly the magnet A will attract

page_text: the armature B; with the said armature B the lever arm C¹ will be fully forced
down and the lever arm C caused to strike with its pin G against the side of the
pendulum E, thus imparting to the same a fresh impulse. The circuit after being
closed is immediately interrupted again. During the remaining part of its throw
the pendulum continues to swing freely, and on its return again strikes against the
pin G whereby the armature B will be lifted once more, and so the clock will con-
tinue to go as long as the battery renders sufficient force to give to the pendulum
the necessary impulse by means of the electro magnet.
To avoid a sliding motion between the pin G and the pendulum, I give the bell-
crank lever the same centre of motion as to the pendulum.
Owing to variations in the electro motive force of the battery or to some
influence of any other kind it may occur that in the course of time the throw of
the pendulum will vary in extent. But as it is essential to avoid any deviations
of the clock from its normal motion, it is necessary to maintain as fully as possible
the perfect isochronism of the vibrations. I have found that such isochronism is
particularly impaired by the friction between the pendulum-rod and the pin G of the.
lever arm C, because there is no absolute coincidence between the centre of motion of
the pendulum and that of the lever, especially where the pendulum is suspended in
the usual manner by means of small elastic blades with which the centre of motion
is not stationary but variable, changing during the oscillation of the pendulum.
The sliding movement thereby occasioned between the pin G and the pendulum is
but slight, but it nevertheless impairs the isochronism of the vibrations of the
pendulum and I therefore have provided means to avoid such sliding movement as
much as possible. For this purpose I provide a sliding surface as shown in Fig 6
applied to an ordinary pendulum, and in Fig 7 applied to a compensator pendulum.
The peculiar feature of said sliding surface consists in its being arranged within
the radial line or approximately the radial line from the centre of motion of the
pendulum. Accordingly the sliding surface with an ordinary pendulum will be
oblique as in Fig 6 and with a compensator pendulum as in Fig 7 the pendulum
rod will receive a slight crank. By this means I obtain indeed as perfect an
isochronism of the vibrations as the normal motion of the clock-work requires.
This
An essential part of my invention is the device for closing and interrupting the
circuit of the battery P at the exact period required for the purpose of effecting an
alternate attraction and release of the armature B by the electro magnet A.
device consists of a little lever I resting on the little ratchet wheel H and catching
into the indentations of the same with a corresponding tooth i.
The said tooth i and lever I are lifted every time that the wheel H is turned by
one tooth through the blade F and as soon as the tooth i has passed the opposite
tooth of the wheel E it will sink again into the next indentation.
Every lift of the lever I brings the same into contact with another little lever K
thus closing the circuit of the battery P.
The electro magnet A is so adjusted in its relative position to the armature B
and lever arm C' that the descent of the latter towards the magnet will cause the
blade F to turn one tooth of the wheel H simultaneously to making contact
between the levers I and K and to interrupt it again a short time before the
armature B actually strikes against the magnet, so that the armature B when
striking upon the magnet will at once be free to be lifted again.
It will be easily seen that the play of closing and opening the circuit through
the contact of the levers I and K as described will follow each other with the
utmost precision, and the more so if, as I have shown in the drawings, the lever I
rests on the same wheel of the dial train which is being turned by the blade F of
the lever C.
. In some cases it may be preferable however to employ two separate little wheels,
a driving wheel and a contact wheel, instead of the one wheel H. and particularly
in the case where the pendulum is desired to receive a fresh impulse, not after
every to-and-fro motion, but where a stronger impulse is to be given at greater
intervals. For this purpose the second or contact wheel will be provided with a

page_text: smaller number of indentations in regular intervals. While the driving wheel as
before is advanced by one tooth after every to-and-fro motion of the pendulum
and stopped by its own ratchet the little contact wheel mounted on the same shaft
will be turned at the same rate and make so many contacts as it carries indenta-
tions. The number of contacts which keep the clock-work in motion may by this
means be reduced as much as convenient. The ratchet of the driving wheel in this
modification cannot be combined with the little contact lever I as in the former,
modification, because such lever must be arranged to work in combination with the ;
contact wheel as before.
It is of great importance that contact be made between the levers I and K at
the time where the arm C¹ and armature B during their descent towards the
magnet A are in close proximity to the same; by this means the attraction, by
which fresh impulse is given to the pendulum and motion imparted to the dial
train, will be worked with an exceedingly small expenditure of electric force.
To obtain a perfectly regular motion of the clockwork it is further important,
but not absolutely necessary, to reduce the gravitation of the lever C C¹ to a
moderate extent. For this purpose the adjustable counter-weights N. N may be
arranged or the parts of the lever C C¹ may be arranged to balance each other as
much as required. The surplus of weight ought to be so far limited to allow the
lever to fall along with the returning pendulum and to effect the contact as
described without however overcoming by its gravitation the weight of the little
lever K. To raise the said lever K. the gravitation of the lever C must first be
enforced by the attraction of the electro magnet and under the influence of the
impulse given by such attraction the dial train will be advanced and the pendulum
receive a push; by this means the regular action of the pendulum will remain
almost perfectly free of the disturbing influence of the lever C and of the dial train.
If the lever CC is balanced as described, it will be seen that when the battery
is open and the pendulum swings the lever C though moving to and fro will
only cause the finger to vibrate on its place without advancing the same, the latter
effect will only be obtained when the battery is closed. The return motion of the
lever C when lifted by the pendulum may be worked by means of a spring instead
of by gravitation. The spring will be so arranged that its tension is produced by
the stroke of the pendulum and when the latter returns the elastic force of the
spring works on the lever to make it return along.
Another part of my invention relates to means for maintaining the contacts
which as is well known are commonly oxidised by sparks which are caused by the
frequent opening and closing of the circuit. Said sparks are occasioned by an
induction which is engendered by interruptions of the main current of the line. To
reduce such induction as much as required for the purpose of maintaining the
contacts, I have provided the following means.
It is well known that every extinguishing current engenders in a neighbouring
conductor an induced current in the opposite direction, said induced current being
the more intense the more the conductor is adjacent and the more it is conductible.
Basing on this principle I have given to the electro-magnet of the electric clock the
following construction as indicated in Fig 5.
Between every two layers of wire on the coils I interpose metallic sheets of
cylindrical form of conducting metal and I also make the skeleton of the coils.
which surrounds the cores of conducting metal preferably of copper of sufficient
thickness. In electro magnets of this kind the skeleton of the coils and the
metallic sheets between the layers of wire so much absorb the reciprocal induction
of the parts that the induced current in the wire is nearly obviated; in consequence
scarcely any sparks will be produced on the contacts and the metal will not be
oxidised.
Another means of maintaining the contacts consists in arranging the little contact
levers I and K in such a manner that on bearing against each other a sliding.
contact is produced. The said arrangement is clearly shown in Fig 4 and it is
evident that a sliding movement must ensue as soon as the levers meet and.turn.

page_text: on their pivots e and d. This sliding movement will be the more remarkable the
greater I make the distance a and the less I make the distance g. The extent of
these distances however is to be kept within certain limits, regard being had to
practical construction.
I have further provided the electric clock of my invention with an arrangement
which though already known in other electric apparatus has never before been
employed in electric clocks the purpose of this arrangement is to facilitate the
connection and disconnection of the wires which connect the battery P with the
electro magnet and with the contact lever K. For this purpose the wire ends which
pass from the electro magnet and from the little lever K towards the battery are
fastened to insulated brackets secured upon the clock; said brackets are provided
with projecting arms which as soon as the clock is properly adjusted in its place in
the box bear against spring clamps to which the wires from the battery are
connected. By this means any person even ignorant of the mechanism of the clock
will be able to take the clock work out of its box for the sake of repairs or for any
other purpose and to re-adjust it, and the wire connection will always be established
without fail.
To intercept the stroke of metal parts against each other in this arrangement of
an electric clock and to secure a perfectly silent motion of the same, I have
provided elastic cushions between the respective parts. Such cushions L preferably
of rubber are arranged between the armature B and the cores of the electro
magnet A and said cushions may as well be secured to the armature as to the cores.
Said cushions also serve to prevent the armature retaining magnetism from direct
contact with the metal of the cores. The cushions ought to be of such little height
as to allow the armature to come into close proximity to the cores, otherwise much
of the attractive force would be wasted.
Another cushion is arranged between the pin G and the pendulum E to prevent
any noise. This cushion may be made in any convenient manner. I prefer to use
a hollow tubular metal pin with an opening at the place where the pin strikes
against the pendulum. A rubber core is inserted into the tube and projects a little
from the said opening. Or the metal pin G may be surrounded by a rubber pipe
with a metal shell to prevent its being spoiled by the oxidising influence of the
air. The shell of course must have an opening at the place where the pin strikes
against the pendulum.
Or the rubber cushion may be attached to the pendulum instead of to the pin G.
A metal shell with rubber inside projecting from an opening in the required place
may be secured upon the pendulum or a rubber pipe surrounded by a metal shell
and projecting from an opening of the same may be drawn over the respective part
of the pendulum rod.
A third cushion may be arranged at M between the little lever K. and the
adjusting screw upon which the lever strikes. By all these cushions or dampers
any noise which might be occasioned by metal striking against metal will be
prevented and the motion of the clockwork will be perfectly silent.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
First In an electric clock the combination with an armature of an electro magnet
of a pawl or clastic blade to turn the driving wheel of the dial train and a pin
bearing against the pendulum, said armature pawl and pin being connected to a
lever which is lifted by the stroke of the pendulum, and which during its descent
makes contact, then, under the influence of the attraction of the maguet, turns the
driving wheel by one tooth, imparts fresh impulse to the pendulum, and the contact
being again interrupted rests in proximity to the electro magnet substantially as
and for the purpose set forth.
Second In an electric clock the combination with the armature of an electro
magnet of a pawl or elastic blade to turn the dial train and a pin bearing against

page_text: the pendulum, said armature pawl and pin being connected to a lever which is so
much balanced that it follows the pendulum by gravitation or by spring pressure
till contact has been made and thence works essentially under the attraction of the
electro magnet substantially as and for the purpose set forth.
Third The arrangement of a sliding surface between the pin G of the lever C and
the pendulum, said sliding surface being arranged within or approximately within
the radial line from the centre of motion of the pendulum substantially as and for
the purpose set forth.
Fourth In an electric clock the device to make contact for alternately attracting
and releasing the armature of the electro magnet, said device consisting of a little
ratchet wheel H in combination with a lever I which rests on and catches into it,
and is lifted tooth by tooth to enter into contact with another little lever K, both
levers being in the same circuit with the electro magnet substantially as and for
the purpose set forth.
Fifth In an electric clock the use of one and the same ratchet wheel H for
working the dial train and for making contact between the levers I and K sub-
stantially as and for the purpose set forth.
Sixth In an electric clock the use of a contact wheel differing from the driving
wheel mounted on the same shaft by the number of indentations for the purpose of
making contact and giving impulse at distinct intervals substantially as set forth.
Seventh The arrangement of the two little contact levers I and K in such
a manner as to produce a sliding contact between them substantially as and for the
purpose set forth.
Eighth In an electric clock the arrangement of an electro magnet, the skeleton
of the coil or coils of which is made of conducting non-magnetic metal such as
copper, for the purpose of counteracting the induction within the wire coils and the
sparks thereby produced, substantially as set forth.
Ninth In an electric clock the arrangement of an electro magnet or electro
magnets, within the coil or coils of which sheet metal cylinders of conducting
non-magnetic metal are laid between the layers of wire for the purpose of
counteracting the induction and the sparks thereby produced, substantially as
set forth.
Tenth The arrangement of an elastic cushion or cushions between the armature
and the cores of the electro magnet, said cushions being secured either to the
armature or to the cores, or to both, substantially as and for the purpose set forth.
Eleventh The arrangement of an elastic cushion between the pin G of the
lever C and the pendulum E for the purpose of intercepting the shock and of
preventing noise substantially as set forth.
Twelfth The arrangement of an elastic cushion between the lever K and screw M
substantially as and for the purpose set forth.