Improvements in Electrical Signalling Systems.
Year: 1899

page_text: Improvements in Electrical Signalling Systems.
I, EDWARD DAVIS, of No. 291, Cambridge Street, Allston, in the City of
Boston, County of Suffolk, and State of Massachusetts, United States of America,
Inventor, 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 has for its object to provide improved means for signalling
between two points, such as a sub-station and the central station of a police
signalling system, the particular object of the invention being to put the central
office in control of the circuit in such manner as to render certain signals
audible or not, according to the will of the attendant at the said central office.
The invention consists in the improvements which I shall now proceed to
describe and claim.
Of the accompanying drawings, forming a part of this specification,―
Figure 1 represents a diagrammatic view of a signalling system organized in
accordance with my invention.
Figure 2 represents a side elevation of one of the transmitting instruments
employed.
Figure 3 represents a side elevation of the same, looking from the other side.
Figure 4 represents a rear elevation thereof.
Figure 5 represents a detail edge view of the contacting wheel in the trans-
mitting instrument.
Figure 6 represents a side elevation of the receiving instrument.
Figure 7 represents a side elevation thereof, looking from the other side.
Figure 8 represents a detail side elevation of the alarm-circuit controller.
Figure 9 represents an end elevation of said alarm-circuit controller, with a
portion of the base of the receiving instrument shown in section.
Figure 10 represents an enlarged sectional view of a portion of said alarm-
circuit controller.
The same reference characters indicate the same parts in all the figures.
Referring to the drawings,
In Figure 1, at the right, the receiving instrument at the central station is
shown, in diagram, while at the left is shown a portion of a transmitting instru-
ment A connected through circuit-wires m m¹ with the receiving instrument.
A number of other transmitting instruments may be included in the circuit,
077

page_text: two such, represented by the letters B and C, being shown in Figure 1 con-
nected in series with the transmitter A. The transmitting instrument consists
essentially of a device for making a succession of breaks in the current over the
main line, in order to transmit a signal, the main circuit being normally closed.
These changes in the circuit are received at the central station by the receiving
instrument, which makes a record of the signal, and which also has provisions
for ringing an alarm when signals of a certain character are received. The
transmitting instrument is constructed as follows: a and a¹ are respectively a
gear-wheel and a pinion, having teeth which intermesh with each other. The
main-line current flows through these members, from one to the other, when the
teeth of the two intermesh. The former has certain of its teeth removed, so as
to make breaks in the circuit when the wheels are revolved, which breaks will
be felt by the receiving instrument. The full complement of teeth a² a² of the
gear-wheel a, represented in Figure 1, would be sixty, while the pinion a¹ has
twelve leaves or teeth. At 2, a space is represented from which two teeth have
been removed, and at 3 is a similar space, the two spaces being separated by a
single tooth, as shown. Following the space 3 is a series of twelve teeth, and
after this are two spaces 4, 5, separated by a single tooth and each representing
two teeth. Following the space 5 is a series of three teeth, and after this are
three equal spaces, 6, 7, 8, each representing two teeth and each separated by
a tooth. After the space 8, the series of teeth is complete to the starting-point.
It will therefore be seen that should the gear-wheel a make one complete revolu-
tion in the direction of the arrow, from its position represented in Figure 1,
and the pinion a¹ be revolved through the open spaces as though teeth were
present, two short breaks would first be made in the current, followed by a long
pause, then two short breaks, a short pause, and three short breaks in succession.
The contact or gear wheel a is mounted on one side of an insulating disk j', on
the other side of which is a gear-wheel j of the same pitch and diameter as the
wheel a but having teeth opposite the spaces of the wheel a, and spaces opposite
the teeth of said wheel. Both of the wheels a and mesh with the pinion a¹,
so that the wheel always carries the pinion over the places in the wheel a in
which there are no teeth, while a good contact is always insured between the
teeth of the wheel a and the teeth of the pinion a¹. With teeth of a certain
pitch, the length of the breaks in the circuit caused by the spaces in the wheel a
may be varied for a given speed of rotation of said wheel by varying the size of
the pinion a¹; for with pinions of a larger diameter, and hence greater number
of teeth, there will always be more of the pinion-teeth in contact with the gear-
teeth at any one time than with a pinion of smaller diameter, so that the breaks
caused by the spaces in the wheel a will be shorter for the said larger pinions,
and longer for the smaller pinions.
On the arbor of the gear-wheels a j is a pinion meshing with a gear-
wheel on an arbor 18. The arbor of the pinion a carries an escape-
wheel engaged by a pallet j'. The arbor 18 on which the gear is loosely
mounted has rigidly attached to its ends a yoke 12, and also at one end a ratchet-
wheel. A small clock-spring is also attached to the said arbor 18 and to
the frame of the transmitter, and a plunger or push engaging a stud j¹ on
the yoke is employed to oscillate said yoke, as represented by the dotted lines
in Figure 3. A pawl 8 pivotally mounted on the gear is held in engage-
ment with the ratchet 10 by means of a spring 1. is a partition, represent-
ing a portion of the inner door of a police signalling box. is a base or frame
of insulating material, attached to the door 16 and carrying the parts of the
transmitter. When it is desired to actuate the transmitter, the plunger 15 is
pushed in as far as it will go, and then released. The ratchet to is thereby
advanced a distance of one tooth under the pawl 8, and upon the release of the
plunger the spring 3, which has been by this action put under increased ten-
sion, causes the rotation of the train of wheels at a speed controlled by the escape-
ment, A suitable stop is provided, to limit the movement of the gear-wheel a

page_text: to one complete rotation, said stop comprising an arm 23 secured to the arbor
and adapted to engage a pin carried on a pivotal arm. The latter is
pivotally connected by means of a link 20, with an arm secured to the
arbor is. When the plunger is pushed in, the arm assumes the position
shown in dotted lines in Figure 3, in which its pin is out of the path of the
arm The latter is permitted to make five complete revolutions, which is
equivalent to one complete revolution of the wheel a¹, before being engaged by
the said pin Current is communicated to the wheel a by means of a metal
brush or spring a3 and to the pinion a by means of brushes at a in contact
with the arbor On the insulating disk jupon which the gear-wheels a
and are secured, is mounted a metal plate adapted to make contact, when the
wheel a is in its normal position of rest, with two brushes a as, one of which
is electrically connected with the pinion a¹ and with the circuit-wire m', while
the other is electrically connected with the gear-wheel a and with the circuit-
wire m.
In the main circuit with the transmitter A, are included a battery E
and a relay-magnet b. The armature of the latter is normally held by the
attraction of said magnet due to the current flowing through the line, against
the poles of the magnet; but when the line current is interrupted, a spring 2
draws the said armature, or the pivotal part carrying the same, against a con-
tact This completes a circuit through two magnets c d in the receiving
instrument, which are connected in series with each other and with a battery F.
The armature of the magnet c is mounted on a pivotal arm ¹, at the end of
which is a marking point c². Above the latter is a thin-edged roller supplied
with ink by an ink-roll, and between the roller and the point runs a
tape e which unwinds from a reel e.3 A pivoted lever f has one arm resting
upon the levere and the other arm equipped with projections fl and f. The
projection is adapted to engage any one of a series of notches f f in a
wheel f For revolving the said wheel f³, a clock-train G is provided, operated
by a weight attached to a cord g' which winds on a barrel g, and controlled by
an escapement g. On the arbor of the escape-wheel is a stop-arm f³ adapted
to be engaged by the second projection f on the lever f. The tape e is pro-
pelled by means of rolls el e², the former of which is driven by the clock-train.
H is a bell-circuit controller, mounted on an arbor which is rotated by the
clock-train G. It will be seen that the first interruption in the main circuit
caused by the break 2 in the gear-wheel a will close a circuit through the
magnet c, whose armature is normally held elevated by means of a spring c
(Figures 6 and 7). Said armature is thereby attracted, and the lever c¹ oscillated
on its pivot, causing the long end of the same to rise and elevate the lever f.
This disengages the projection f' from the notch in the disk f3 with which
it is in engagement, and likewise disengages the projection f* from the stop-
arm f, whereby the wheels of the clock-train are permitted to rotate. The
cessation of the impulse in the magnet c causes the arm c¹ to drop, and allows
the projection f to rest against the periphery of the now revolving disk f³. As
soon as the next succeeding notch comes underneath the projection f¹, the
latter will fall into the said notch and bring the projection f into the path of
the arm f. This occurs after one complete revolution of the bell-circuit con-
troller H. The armature of the magnet d is carried at the lower end of a
pivotal arm d', which carries a spring-brush and has a pin projecting
from its upper end. is a bell, one of whose terminals is connected with a
brush d, having electrical connection through the arm d', with the spring-
brush, and the other of whose terminals is connected with a metal disk h¹
forming a part of the circuit-controller H. The bell-circuit also includes a
battery J. In the disk is bored a series of holes h5 h5, and on the face of
said disk is mounted a disk of insulating material, the latter carrying a
pin adapted to enter any of the holes . Said insulating disk loosely sur-
rounds the arbor 2, and is held against the face of the disk by means of a
spring interposed between a nut on the end of the arbor, and a knob s

page_text: screwed into the center of the disk 3. Extending part-way around the periphery
of the insulating disk h³, is a projecting flange, and the gap between the ends
of the latter is partly filled by a boss 10 extending from the rim to the center
of the disk. Between said boss and the flange hare short gaps or spaces 9, 10.
The relation of the pivotal arm and its connected parts, with the disk ³, is
such that if the magnet d attracts its armature while the space 9 is opposite the
pin on the upper end of the arm d, and the disk his revolved, said pin &³
will enter the gap 9 and become engaged with the flange , as represented in
Figure 8, causing the rim of the metal disk h¹ to be brought into engagement
with the spring-brush on the arm d'. This completes a circuit through the
bell i, and causes the same to ring. The rim of the disk his cut away for a
portion of its length, as represented, so that the circuit will not ordinarily be
immediately completed upon the entrance of the pin ³ into the gap 9. When
the pin has been engaged by the flange 19, the continued revolution of the
disk brings the boss 10 into engagement with the said pin, and the said boss
exerts a cam action upon the pin 3, and moves it out again to the rim of the
disk h³, which action breaks the bell-circuit. The arm has no spring attached
to it, but is frictionally mounted on its pivot, and is moved only by the magnet d
or by the described cam action of the boss 10.
In order to secure the best results with the apparatus, the bell-circuit con-
troller H should be timed to revolve substantially in unison with the gear-
wheel a.
The synchronism need not be exact, but should be approximate.
The operation of the apparatus is as follows: Using the transmitter shown in
the drawings as an illustration, it may be supposed that the plunger 15 has been
pushed in and released. In order to prevent any interruption of the current
between the gear-wheel a and the pinion a, due to the pressure of the former
against the latter being relieved when the plunger is pushed in, the brushes a
are made to co-operate with the contact-plate a, in order to preserve the circuit
until the wheel has started to revolve. The first break 2 in the said gear-
wheel a actuates the relay and energizes the magnets c and d. This causes
the release of the gear-train G, and starts the bell-circuit controller H in revo-
lution, and at the same time, a dot is imprinted on the tape e. The next
break 3 imprints another dot on the tape, after which a comparatively long
pause occurs, and then two dots in quick succession, followed by three more dots
in quick succession, are imprinted on the said tape by the action of the spaces 4,
5, 6, 7, 8. If the insulating disk ³ in the receiver has been so adjusted with
respect to the disk has to bring the gap 9 opposite the pin d³ during the time
that the two breaks 2, 3, in the wheel a are passing the pinion w, the attrac-
tion by the magnet 6 of its armature will cause the pin 3 to enter the gap 9
and close the bell-circuit; but if such passage of the gap 9 past the pin d³ does
not occur at the time that the breaks 2 and 3 are passing the pinion a¹, the pin
will not enter the gap, but will remain on the outside of the rim of the disk h³.
If the magnet attracts its armature when the disk is presenting a con-
tinuous portion of its periphery, such as any part of the flange h³, or the edge
of the boss 10, to the pin 3, said pin will merely be pressed against said por-
tion during the existence of the impulse, but will produce no effect on the bell
circuit. Since the disk may be adjusted to any desired relation with respect
to the metal disk ', which latter is always in a fixed relation to the clock-train,
this adjustment being accomplished by moving the said disk out from the
face of the disk to insert the pin in the proper hole, it follows that it
is at the option of the attendant at the receiving station to receive or not to
receive an audible signal from the transmitter A. In adapting my invention
to a police signalling system, each of the street boxes or 'sub-stations" will
ordinarily be equipped with several transmitters A, each comprising two contact-
wheels and push mechanism for actuating the same, for the purpose of
transmitting signals of different character to the central station. The several
transmitters are connected in series with the line m m², and each is synchronized

page_text: with the bell-circuit controller H in the receiving instrument, as previously
described. The peripheries of the gear-wheels a in the several transmitters con-
tained in the street box preferably have their teeth so disposed as to give, first
the special signal corresponding to that transmitter, and then the number of the
box, both of which signals are recorded on the tape of the receiving instrument.
If the central office wishes to be notified when a certain signal is turned in,
without having to watch the tape for the record of the transmitter giving that
signal, the attendant merely adjusts the disk h³ on its base h¹, so that the gap 9
will be brought opposite the pin at the same moment that a blank space on
the wheel a of that particular transmitter is passing the pinion . The result-
ing break in the line circuit will then energize the magnet d at the proper
moment to move the pin into the gap 9, and close the bell-circuit. The
scheme of the spacing on the contact-wheels of the several transmitters must of
course be known to the receiving attendant, in order to enable him to set the
receiver for an audible alarm on any desired signal.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is
1. In a system for transmitting signals, the combination of transmitting
apparatus adapted to transmit a number of signals of differing characteristics, a
receiver adapted to receive said signals, an alarm, and an alarm-circuit controlling
apparatus in part controlled by the receiver and in part controlled by the trans-
mitting apparatus, these parts being relatively adjustable to permit the sounding
of the alarm for any of said signals, while excluding others, at the will of the
receiving attendant."
2. In a system for transmitting signals, the combination of a transmitter
having main-circuit controllers adapted to transmit a number of different
signals, and motor mechanism for driving said controllers, an alarm, and a re-
ceiver adapted to receive said signals and having an alarm-circuit controller and
a motor for driving the same, the said alarm-circuit controller being set in
motion by a current-impulse from the transmitter and synchronized therewith,
and having provisions for adjustment to cause the alarm to be sounded for any
of said signals, while excluding others, at the will of the receiving attendant.
3. In a system for transmitting signals, the combination of the main circuit,
an alarm, a clock-train, an alarm-circuit controller driven by said clock-train
and comprising a rotary part having fixed starting and stopping points, a part
adjustable thereon to different positions, a movable member co-operating with
said part in the control of the alarm circuit, and an electro-magnet controlled
from the main circuit and adapted to move the last said part.
4. In a system for transmitting signals, the combination of the main circuit,
an alarm, a clock-train, an alarm-circuit controller driven by said clock-train
and comprising a rotary part having fixed starting and stopping points and
carrying one terminal of the alarm-circuit, a part adjustable thereon to different
positions and having a segmental peripheral flange and a peripheral boss
separated by spaces from the ends of said flange, a movable arm carrying the
other terminal of the alarm-circuit and having a projection normally located
outside of said segmental flange but adapted to pass inside thereof and thereby
bring the alarm-circuit terminals into contact, and an electro-magnet controlled
from the main circuit and adapted to operate said arm.
5. In a system for transmitting signals, the combination of a main circuit, a
transmitter adapted to transmit a number of different signals over said circuit,
an audible alarm, and a receiver comprising a recording mechanism adapted to
record said signals, an electro-magnet for operating said mechanism, an alarm-
circuit controller controlled by the receiver, and an electro-magnet co-operating
therewith to operate the alarm-circuit, the said electro-magnets being energized
by all the current-impulses from the transmitter, and the alarm-circuit con-

page_text: troller being adjustable and so constructed as to cause the alarm to be sounded
for any of said signals, while excluding others, at the will of the receiving
attendant.
6. In a system for transmitting signals, the combination of a transmitter
comprising a pair of gear-wheels forming the terminals of a circuit and having
their teeth engaged, one of said wheels having an incomplete number of teeth,
whereby one or more breaks are made in the circuit, means for rotating said
gear-wheels, and a receiver adapted to respond to the current-impulses impressed
on the circuit by said transmitter.
7. In a system for transmitting signals, the combination of a transmitter com-
prising a gear-train including a pair of intermeshing gear-wheels which form
the terminals of an electric circuit, one of said gear-wheels having less than its
full complement of teeth, whereby one or more breaks are made in said circuit,
and a gear-wheel included in the train on the same arbor with the last said
gear and having teeth opposite the place or places where the latter lacks teeth,
and lacking teeth opposite the place or places where the latter has teeth, means
for driving said gear-train, and a receiver adapted to respond to the current-
impulses impressed on the circuit by said transmitter.
8. In a system for transmitting signals, the combination of a transmitter com-
prising a gear-train including a pair of intermeshing gears which form the ter-
minals of a circuit and are constructed to impress a series of current-changes on
said circuit, a spring or equivalent for driving said gears, an actuator connected
with said spring and adapted to start the train in motion, and a switch adapted
to maintain the circuit complete during the manipulation of said actuator, and
a receiver adapted to respond to the current-impulses impressed on the circuit
by said transmitter.
9. In a system for transmitting signals, the combination of a transmitting
apparatus adapted to transmit a number of different signals, a receiver adapted
to receive said signals, an alarm, and an alarm-circuit controlling apparatus,
with provision for adjustment to cause or permit the sounding of any of said
signals, or to exclude all of said signals, at the option of the receiving attendant,
said controlling apparatus being under the joint control of the receiver and the
transmitting apparatus.
10. In a system for transmitting signals, the combination of a transmitting
apparatus adapted to transmit a number of different signals, an alarm, and a
receiver adapted to receive said signals, with an alarm-circuit controlling
apparatus consisting of two co-operating elements, one responsive to all the
signals sent by the transmitter, and the other under control of the receiver and
adjustable to cause the alarm to be affected by any one or none of the signals,
at the will of the receiving attendant.
11. In a system for transmitting signals, the combination of a transmitting
apparatus adapted to transmit a number of different signals, a receiver adapted
to receive said signals, an alarm, an alarm-controlling device responding to the
transmitting apparatus, and a controller therefor governed by the receiver and
adjustable to cause or permit the operation of the alarm-controlling device for
some of the signals received and not for others, at the will of the receiving
attendant.
Dated this 1st day of July 1899.
Haseltine, Lake & Co.,
EDWARD DAVIS,
45, Southampton Buildings, London, W.C., Agents for the Applicant.