Apparatus for Calling any desired Station on a Telegraphic or Telephonic Line.
Year: 1894

page_text: COMPLETE EUIFICATION.
[Communicated from abroad by FRANZ TRINKS, Technical Director of Grimme,
Natalis & Co., Brunswick, Germany, Engineer.]
Apparatus for Calling any desired Station on a Telegraphic or
Telephonic Line.
I CHARLES BRADBURY, of 249 High Holborn, London, W.C. Agent, 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 call signal apparatus whereby any number of stations on
an electric telegraphic or telephonic circuit are put in communication in such
manner that each station can call any one of the other stations by means of an
audible signal without actuating the audible signals at the other stations.
This object is attained by providing at each station an apparatus composed of
three instruments, namely firstly; a clockwork mechanism serving as a starting
apparatus, that is liable to be set in motion by every electric current that is sent
through the line wire in signalling, but the motion of which, when only ordinary
telegraphing currents of very short duration are passed, is arrested before it can be
made to actuate a second clockwork apparatus which puts the call signal into
action, this being only possible when a current of a certain duration is sent, and
this call signal apparatus contains a controlling device whereby the operator at a
certain station can determine that the call signal shall only be put in action at the
particular station with which he desires to communicate.
The above two apparatus are actuated by electric currents both from the main
circuit and from a local circuit, and there is a third apparatus consisting of a
commutator device whereby the connections of the starting apparatus and the call
signal apparatus with these two circuits are reversed at certain points of their
action.
I will proceed to describe the construction of these several apparatus and their
mode of operation with reference to the accompanying drawings, in which
Fig. 1 shews a front elevation of the three instruments combined.
Fig. 2 shews an end view of the call signal apparatus and section of the
commutator.
Fig. 3 an end view of the starting apparatus.
Figs. 4 and 5 shew diagrams of the electrical connections and their mode of
action.
Figs. 6, 7, 8, 9 and 10 shew details of the arrangement and mode of action of the
apparatus.
A is the starting instrument and A is the call signal instrument, while U is the
commutator.
The instruments A and A° are both contained within the same framing P¹; each
instrument is actuated by a separate clockwork driven either by spring action as
shewn, or by weights. The main spindle g and 2° of each instrument is made to
perform a complete revolution by the clockwork when released by the locking
device H and Ho, unless it is stopped by.certain other stopping devices. The speed
of rotation is controlled by a flyer on the clockwork.
The system of telegraphic signalling on the main circuit on which these apparatus
are used, may either be that in which an ordinarily closed circuit is momentarily
interrupted for sending signals or that in which an open circuit is momentarily

page_text: closed for that purpose. In the arrangement shewn, the first named system is
assumed to be employed.
Each instrument has an electromagnet e and e°. When no signalling is being
effected the continuously acting current passes through the coils of the electro-
magnet e and attracts the armature aº.
In order that the armature a of the magnet e may also be attracted under the
above conditions so as to prevent useless movement in the instrument A, there is
provided a local battery at each station, the current from which flows through e.
Both currents pass through the commutator U which is so arranged that it can
connect each circuit alternately either with the coils of e or with those of e°.
Figs. 4 and 5 shew diagrammatically the two opposite connections, Fig. 1
shewing the main circuit connected to e° and the local circuit connected to e.
If by means of the switch K Fig. 4 the closed main circuit be interrupted, the
electromagnet e will cease to attract its armature a", which will consequently drop.
This armature is fixed on a lever C° turning on a fixed pivot at 60 Fig. 1 and
pivotted at its free end to a rod do the upper end of which is pivotted to a lever Do
turning on an axis at º and having a finger k° (shewn dotted in Fig. 1) which by
the downward motion of do and D° presses upward the finger 1° of the double
locking catch Ho, (which may be of any known construction) thereby disengaging
the latter from the clockwork. In addition a locking device R° carried by d° is
also moved out of engagement with the clockwork, the arm Zo being thereby made
to slide off the pin n° and thus causing the arm yº to move back and release an
arm on the axis of the flyer of the clockwork, so that the apparatus A° is now set
in motion thereby.
The lever c is connected by means of the joint so Fig. 3 with a lever F° which
has its fulcrum at hº, and is connected at p° to the rod Jo the upper end of which is
connected to the elbow lever og pivotted at . The arm go embraces with its
forked end the grooved boss of a disc So sliding loose upon the axis qº. This disc
is acted upon by a spiral spring f which tends to bring it back into a certain
position of rest after it has been turned on its axis. This position is determined by
by a pin a* which bears against a stop V projecting from the side of the framing P¹,
to which stop the one end of the spring fo is also attached.
0
The disc So carries on its inner face a half clutch, the other half of which is
fixed on the spindle 7°. By the before mentioned descent of the armature aº, the
disc So is slid inward on the spindle q° so as to cause the half clutches to become
engaged, whereby the disc is caused to follow the rotary motion of the spindle qº.
If after such commencement of motion, the line circuit be at once closed again
at K Fig. 4, so as to cause the armature a° to be attracted again, the consequent
upward movement of do will cause 2° to slide upward on the pin n° again and yo will
again stop the rotation of the arm and consequently of the clockwork. The
double locking catch H° can however not become engaged again, as this can only
take place when 9° has performed complete revolution.
The locking catch R can however be prevented from arresting the clockwork
of A° for a certain time after leaving the position of rest determined by H°; this
is effected by a stop device E° d* Fig. 1 as follows. E is a slide having a slot
with which it slides vertically over two fixed guide pins, and which is pressed
downwards by the two armed lever d* having spring action; the lower end of the
slide on the other hand is pressed upward by a cam (not shewn) on the spindle qº
when this begins to rotate, so that such upward motion causes the lever arm 2° to
be pressed down upon the pin n°, and in thus preventing the arm 2° of R° from
coming in contact with that pin, it also prevents the arm y° from stopping the
motion of x. At the same time the lever F" rod Jo and lever, in being moved
upward by the attracted armature, will withdraw the disc So from engagement with
the spindle 9º, so that the spring will bring the disc back into its position of rest
as at Fig. 3.
The above described action is repeated every time the line circuit is interrupted
and then immediately closed again for sending a telegraph signal; the locking

page_text: device Ko serves, when not prevented by the lever to stop during the operation
of telegrapbing, any useless motion of the clockwork mechanism.
I will now consider a telegraphic circuit having say five stations, and assume
that an operator at station I desires to call station III, for which purpose he places
the sliding contact E, Figs. 1, 2, 4, 5, to be presently explained, upon the vulcanite
strip of disc D which corresponds to station III.
If now the line circuit be interrupted for a sufficient length of time by the
contact K Fig. 4, the starting instrument A° will be set in motion as above
described, carrying the disc S° round with the spindle °. When this motion has
continued a certain length of time in the direction of the arrow Fig. 1, a notch po
on the disc So is brought into the highest position, in which a tooth m" on a lever h
pivotted at m* can drop into it, thereby stopping the disc S" in this position, as
shewn at Fig. 7. During the above motion, the stud a* of So will have come in
contact with the tail Cx of a lever C° and in .pressing the tail outwards, will cause
the lever Co to press a contact spring K° connected with the local battery circuit,
away from a contact as shewn at Fig. 7, thus breaking the local circuit, and
thereby rendering the electromagnet e of instrument A inoperative.
The armature a consequently drops, and the lever c carrying it, turning on its
pivot b draws down the rod d. This rod has at its upper part two slots d* and ex
of which ex serves to guide the rod in sliding over a fixed pin f, while d* carries in
it the arm g of the two armed lever g h mounted on an axis i, so that g being drawn
down by d, the arm his raised.
On the axis is also fixed a finger (shewn in dotted lines in Fig. 1) which
engages with the finger of the locking catch H, of any suitable known construction
for locking the clockwork. When in a state of rest, a tooth m on the arm / rests
upon a shallow notch o in .the periphery of the disc S. The notch o is only just
deep enough to hold the lever g h and thereby the fingers kl in such a position
relatively to each other that the locking catch H can engage with the clockwork.
From what has been stated it will be seen that by the downward motion of d aud g
the finger will be raised so as to lift the locking catch H out of gear, and thus
allow the clockwork to be set in motion. By this motion, firstly the starting
apparatus A° is. brought to rest again, and secondly the commutator U is reversed.
These operations are effected as follows:
The pin Figs. 1 and 2 on the toothed wheel u strikes against the lever Y pivotted
at which in being lifted raises the lever h° and its tooth m" thereby withdrawing
the latter from the notch p°, so that the clockwork of A° can now continue its
motion until it arrives at its position of rest determined by the locking catch H°;
during this motion the locking device R° is rendered inoperative by the action of
the device E° d* ° as before explained. The stud 0° on the disc So, Fig. 1, in
revolving with the latter, is brought in contact with a fixed incline u° whereby S°
is pushed back so as to be disengaged from the clutch, whereupon S° will be at
once brought back to its position of rest by the spring fo.
to
. A wiper P on the spindle g of the apparatus A is made by the rotation of
press downwards the lever z pivotted at px, thereby reversing the position of the
commutator U so that it now establishes the connections of the two circuits as at
Fig. 5, whereby the electromagnet eo is included in the local circuit, and the
electromagnet e is included in the main circuit.
The commutator U Figs. 1 and 2. consists firstly of a U shaped support Fu
having centres fu carrying the commutator disc Su, and having on one side an
upward extension d u carrying the contacts h u with the posts gu arranged in a
circular arc. Secondly the commutator disc Su carries the contacts iu with
posts u, which contacts move over the contacts hu and have copper springs mu
which on the turning of Su, make contact already before the contact dises huiu
touch each other. All the contacts and posts are insulated from Su.
Thirdly. There are connecting pieces a u, bu, the forked upper ends of which
are attached to the disc S u and which have slots at their lower ends into which
take the ends respectively of the tail cu of the armature lever C, and of the lever,

page_text: which, as before stated, is pressed downward by the wiper P and is drawn upward
by a spring a. The slots in a ubu are of such a length, that it is only the downward
motion of the lever cu and z that can be imparted to the disc Su, as the levers
can move freely in an upward direction in the slots. Thus owing to these slotted
connections the lever z can move the disc S u independently of any motion of the
lever cu, as on the sinking of the armature lever c, c u will rise up in its slot, and
allow Su perfect freedom of motion.
The electromagnet e has, as before stated, been put in the main circuit by the
reversal of the commutator, but the circuit is still interrupted, notwithstanding
that the spring contact K° has been closed again by the resumption of the
position of rest of A° for the reason to be presently explained.
The disc S fixed on the spindle g has, in addition to the notch whose depth is
only sufficient to bring the locking catch H into action, as before explained, a
second deeper notch p. When the tooth m of lever h drops into this notch, a
copper plate carried by an insulating block n on the end of lever h will drop into
contact with the studs D* introduced into the shunt circuit of the signal bell, so
that when this is done this circuit is closed, and the signal bell L would thus be
sounded.
A stop however tends to prevent the engagement of the tooth m with the
notch p; this stop is carried by a two armed lever F which is pivotted at 9*. The
arms of this lever lies in the path of a stud m* on the rod d, so that the downward
motion of this rod in depressing the arms against the action of a spring m*,
causes the stop r to move backwards away from m, while if s is free, the spring n*
will move forward. This can however not prevent the engagement of the
tooth m with the notch o, because in this position of the disc, the wiper t on the
spindle q pushes the lever F backward, as shewn at Figs. 1 and 6. It is of course
not possible for the tooth m to pass into the notch p so long as no current excites
the electromagnet e. The stop is in this case in the position shewn at Fig. 8.
On the other hand the tooth cannot fall into notch p on closing the circuit at the
time when the notch is advancing towards it, because in that case the stop has
time to advance under the tooth m and thus to hold it up while the notch p is
passing underneath it, as shewn at Fig. 10.
If however the closing of the electromagnet circuit is effected at the same
moment when the notch p has arrived immediately beneath the tooth m, this can
fall into it, because the distance which the tooth has to pass through is shorter
than that which the stop r has to pass through, and because on the rising of
rod d the lever g can at once rise in the slot d* while the lever F must follow the
entire upward movement of d, so that the stop will only arrive against the side
of the tooth m after this has descended into the notch p as shewn at Fig. 9, and
the circuit of the call bell being thus closed, the latter will be sounded.
If now the notch p be arranged in a different position on the disc S at each
station, relatively to the position of the notch o, it will be seen from the foregoing
that it will be possible for each station to stop the starting apparatus and to
actuate the call signal of any other station if it can close the main circuit at the
same moment at which the notch p of the station to be called arrives beneath the
tooth m.
This is rendered possible by the controlling disc D which is fixed on the same
spindle g as the disc S. Into this disc which is of conducting material, there are
let in concentric segmental strips of vulcanite of varying lengths, as shewn
at Figs. 4, 5, 6 and 8 to 10. The commencements of all the strips lie in one and
the same radial line, corresponding to the position of the notch o which is the
same in all instruments, while the positions of the other ends of the strips
correspond with the several positions of the notches.p. The controlling disc D,
in rotating, slides between two sliding contacts E that are interpolated in the
circuit as indicated at Figs. 4 and 5 and that can be moved in a radial direction
and whose conducting connection through the disc D is interrupted so long as they
rest upon the vulcanite strips, as shewn at Fig. 5..

page_text: When no station requires to call another one, the contacts E must of course be
in such a position that on any rotation of D their conducting connection will not
be interrupted by any of the strips so as not to interrupt the line current, i.e. they
must be in contact either with the central portion or with the outer periphery of
the disc.
In practice, the strip corresponding to a particular station is omitted from the
disc at that station, as this does not require to operate its own call.
Assuming now that station I requires to call station III then at station I
the sliding contacts E are moved by any suitable means by hand on to the
commencing edge of strip 11, as at Fig. 4. The starter A° of all the instruments
having been set in motion by sending a current of a certain duration, the spring
contact K will have been moved by lever c° so as to break the circuit of electro-
magnet of calling apparatus A of each station (Fig. 7) so that all these
apparatus are now set in motion by their clockwork, causing the commutators U
to reverse the connections of the main and looal circuits as described. The current
of the main circuit will however be immediately afterwards interrupted, because
the insulating strip 11 of station I will have been brought between the two
contacts E. In consequence hereof the armatures a cannot be attracted, and the
notches p' and p" of stations I and II, will move past the teeth m of the levers h,
these being held up by the lowered rod d as at Fig. 8. The apparatus of
stations I and II will consequently regain their position of rest without the call
signal being actuated.
The rotation of the discs D continues until the end of strip at station I has
passed from between the contacts E. At this moment the main circuit will
consequently be closed and the armatures a at all the stations will be attracted.
At this same moment also the notch pl¹ of station III will have arrived below its
tooth m and this will consequently fall into it, as before described, as shewn
at Fig. 9, and the call signal will be sounded at that station. The stop rat
etation III will in moving forward, butt against the side of tooth m, as before
stated at stations IV and V however, as the notches p and p are still
advancing towards the teeth m, which rest on the peripheries of the disc D, the
stops will have time to advance below the teeth as at Fig. 10 and to hold them
up by the time the notches arrive beneath them, so that the levers h being
prevented from falling, the call signals of these stations will not be sounded, and
the discs will continue to revolve until the apparatus resume their positions of rest
determined by the locking catches H.
After the signal has been sounded at station III, the attendant has to raise
the lever h so as to stop the call bell, and the discs S and D will then continue
their motion until they also arrive in the position of rest.
The commutators U will also have to be brought back to their position of rest
by means of the levers cu on the closing of the main circuit.
As before stated the drawings shew the arrangement for signalling by the
breaking of a closed circuit; in applying the invention to the system of signalling
by the momentary closing of a open circuit, it is only necessary to arrange the
electro magnets in the reverse position relatively to the fulcra 66° that is to say,
to make the levers c and co two armed, and to modify the contact K in a
corresponding manner.
The alterations in the starting apparatus A° which are necessary for this purpose
are shewn at Fig. 11. The fulcrum 6° of lever co is put on the side of the electro-
magnet opposite to that shewn at Fig. 1, and the lever is provided with a tail c
having an adjustable weight G. The lever is otherwise connected with the
apparatus by means of the rods d° and Jo in precisely the same manner as
before.
Thus, the circuit being broken in the state of rest, no current passes through
the electro-magnet eo, and the armature aº is consequently drawn down, as shewn,
by the weighted tail of the lever co this being then made to control the parts of

page_text: the apparatus A° in precisely the same manner as is the case when it is in the
position with the armature attracted as at Fig. 1.
When the circuit is closed for signalling, the armature a is attracted, and the
lever co then sets the apparatus in action in the same manner as is the case when
the circuit is broken in the arrangement at Fig. 1. In precisely the same manner
the fulcrum of lever e in apparatus A is shifted over to the other side of the
electromagnet and the tail cu is weighted instead of the lever c itself so as to hold
the lever in the position shewn at Fig. 1 but with the armature removed from the
electromagnet e when the main circuit is broken, and the apparatus is in a position
of rest.
The only other alteration required in the apparatus is that the lever C* C° of
apparatus A°, instead of pressing the spring contact K° away from its contact piece,
when actuated by the disc So, is made to press it against its contact piece, this being
arranged on the side thereof opposite that shewn at Fig. 1.
For telephonic lines, the current impulses sent through the line wire in speaking
are too weak to put the calling apparatus into action, and consequently the
starter A and commutator U are unnecessary and are dispensed with, as are also
the levers Y and Z of apparatus A and the electromagnet e of the apparatus A is
then simply connected to the line wire, so that when the ordinary electro-magnetic
call apparatus of a telephone is put in action, at the calling station, after setting the
contact lever E of disc D of the apparatus at that station in the proper position a
current is passed along the line and is made to actuate the call apparatus at the
particular station which it is desired to call, in the manner hereinbefore
described.
Having now 7. particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, 1 declare that what 1
claim is:-
1. In apparatus for calling any station on a telegraphic or telephonic circuit, an
electromagnetic device, operating in combination with a clockwork mechanism and
a call signal in such manner that a change of electrical condition produced in the
said circuit of greater duration than that for ordinary signalling, effects the
breaking of a local circuit whereby the said electromagnet becomes inoperative and
by the motion of its armature starts the clockwork, which actuates a contact disc
so as at a certain point of its revolution to make a contact and causes a current to
be sent through the main circuit which brings into operation the call signal at the
desired station, substantially as described.
2. In call signal apparatus such as is referred to in the first claim the use of a
starting apparatus such as A° wherein an electro-magnetic device operates in
combination with a disc So actuated by clockwork and a contact device Ko on the
circuit of the call signal apparatus A in such manner, that on a change of electrical
condition of a certain duration in the main circuit, the said disc operates the
contact so as to break the said circuit and start the call signal apparatus in motion,
while if the said change of the electrical condition be of shorter duration the said
disc So is disconnected from the clockwork and is brought back to its position
of rest before it can actuate the contact, so that the call signal apparatus is not
operated, substantially as described.
3. In call signal apparatus such as is referred to in the first claim the combination
with an electro magnetic apparatus, of a disc S operated by clockwork mechanism,
a contact lever h controlled by the said disc and a call signal circuit controlled by
the said contact lever, these parts being so arranged that on the breaking of the
circuit of the electromagnet, the said disc is set in motion and allows the contact
lever to close the call signal circuit so as to operate the signal, if at the same
moment that a notch on the disc S is brought underneath a tooth m on the contact
lever the electromagnet circuit is closed again, while if such closing of the
electromagnet circuit is effected before or after the notch of the disc comes into the

page_text: said position, the contact lever will be prevented from making contact, and
the disc will continue to revolve until it comes to a point of rest, substantially as
described.
4. In call signal apparatus such as is referred to in the third claim, the use of
a contact disc D made to revolve together with the notched disc S and so arranged
with a series of contacts differently situated relatively to the said notch p on the o
disc, and, operating in combination with an adjustable sliding spring contact on
the electro magnet circuit, in such manner that according as the sliding contact is
adjusted so as to make contact with the one or other of the disc contacts, the
electromagnet circuit will be closed either at the moment when the said notch is
under the tooth of the contact lever, or before or after that moment substantially
as described.
5. In call sigual apparatus such as is referred to in the third and fourth claims,
the use of a stop device r so arranged and actuated by the armature of the electro-
magnet, that when the circuit of the latter is closed before the moment when the
notch p of the disc arrives below the tooth m of the contact lever, the armature
causes the stop to be brought beneath the tooth of the lever, and thus prevents
the tooth from entering the notch when this passes underneath it, substantially as
described.
6. In combination with a call signal apparatus such as referred to in the first
and second claims, the use of a commutator such as U so arranged in connection
with the main circuit and with the local circuit that in one position of its moving
contacts it puts the electromagnet circuit of the starting apparatus A° in connection
with the main circuit, and the electromagnet circuit of the call signal apparatus in
connection with the local circuit, while in another position it reverses these
connections, the moving contacts of the commutator begin brought into the first
named position by a lever acted upon by the disc spindle g of the call signal
apparatus, when this comes into the position of rest, while the contacts are brought
into the last named position by the lever c of the electromagnet armature when the
circuit is broken, substantially as described.
7. In call signal apparatus, the use of starting mechanism A° arranged and
operating substantially as described with reference to Figs. 1, 3 and 7 of the
drawings.
8. In call signal apparatus, the use of starting apparatus A constructed and
operating substantially as described with reference to Figs. 1, 2, 4 5 6 8 9 and 10
of the drawings.
9. In call signal apparatus the use of a commutator apparatus constructed and
operating substantially as described with reference to Figs. 1, 4 and 5 of the
drawings.
Dated this 27th day of T1001
ABEL & IMRAY,
Agents for the Applicant.