Improvements in Telephonic Installations.
Year: 1894

page_text: Date of Application, 4th Aug., 1894-Accepted, 3rd Aug.,
1895
COMPLETE SPECIFICATION.
Improvements in Telephonic Installations.
GEORG RITTER of Markt No. 2 Stuttgart Germany, Telegraph Inspector,
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 :-
The object of this invention is an installation wherein all the manipulations
required for connecting or disconnecting the subscribers of a telephonic network
can be effected by the insertion or withdrawal of a plug switch.
In the accompanying drawings
Fig. 1 shows such an installation wherein a multiple plug switch is used in a
single line, with an arrangement of double cords.
Fig. 2 is a plug switch for answering a calling subscriber.
Fig. 3 is a plug switch for connecting the called for subscriber.
Figs. 4 and 5 are modifications of the plugs shown in Figs. 2 and 3.
Fig. 6 shows the circuit when the invention is applied to commutators frames or
chests operated by a single cord arrangement.
Fig. 7 shows the direction of the current or circuit for double lines.
For the purpose of this invention the play switch is so constructed that by its
means, besides the required connections for establishing or breaking off a commu-
nication between two subscribers of a telephonic installation, call bells can be
operated, fallen closing valves can be raised, and so far as appears desirable the
subscribers' circuits can be broken.
This installation which will answer as well for the single as for the multiple
switches of single or double lines with a single or double cord arrangement will
now be described in connection with a multiple switch for a single or double line
with a double cord arrangement.
With reference to Fig. 1. 2 are two subscribers circuits which pass through
the terminals or contacts or and the coil W' of the respective electro-magnets
of the annunciator in order to be connected to earth.
For making pairs of plug switches I, II, II are used one of which serves for
answering the call of a subscriber, while the second s² is always used for connecting
the called for subscriber.
The plugs (Fig. 2) consists of the contact making and breaking core 1, and the
collar 2 both of which are insulated from one another and are firmly connected in
any suitable manner to the switch handle inade of insulated material. Upon the
latter are further mounted the three fixed metallic rings 3, 4 and 5 as well as an
adjustable bush 6 by means of which the three fixed rings are electrically connected
together. The spiral spring 7 is fixed in any suitable manner to the bush 6 and has
With the
a tendency to constantly pull the latter back into its position of rest.
plug are connected the following circuits: The connecting circuit to the plug
which passes at the same time through the coils of the electro-magnet e of the
closing device c by the aid of the core 1. and of the ring 3; the circuit to the
switchmans telephone by the aid of the ring 5. a circuit which leads through
the ring 4 to the coils of the auxiliary electro-magnet of the closing device and
to the test battery p and lastly a circuit directly leading through the collar
the same pole of the test battery p as the last mentioned circuit.
to
The plugs (see Fig. 3) has a cylindrical contact making and breaking tube 9 in
the axis of which is arranged, so as to be insulated from the said core, the test rod

page_text: or core 8; the collar 10 has exactly the same shape as that of the plug & abov
described; these three are insulated one from the other and are fixed to the plu
handle made of insulated material. Upon the latter are also fixed three metalli
rings 11, 12 and 13 while a collar, the inuer periphery of which is recessed, i
adjustably mounted thereon and is constantly held back in its position of rest by a
spiral spring 15. The following circuits are connected to the plug switch the
connecting circuit leading to the electro-magnet e' of the closing
device and hence to the plug switch through the ring 13 and by means of the
or circuit breaking
bush 14 through the ring 11 .e. the tube 9; the circuit to the telephone of the
switchman through the test rod 8, the circuit to the test battery through the collar 10
and lastly the circuit to one pole of the call battery r
The other pole of the latter battery as well as that part of the telephone which is
through the ring 12
not connected to the plug switches are connected to earth (see Fig. 1). From the
pole of the test battery which is furthest from the plug switches start circuits
passing around the auxiliary electro-magnet of the annunciator and leading to
the contact rings of the subscribers circuits where they end and are
insulated the last mentioned pole of the test battery is moreover connected to the
side of the telephone t which is connected to earth.
P
It may
be further mentioned that the annunciator f as well as the closing device e
are made of magnetic material so that they can be drawn back into a vertical and
closed position by the magnetic force developed from time to time in the auxiliary
coils or eª.
The connection between the two subscribers is carried out in the following
manner.
Assuming that subscriber No. 1 for instance desires to speak to subscriber No. 2
the armature a of the annunciator will be attracted in consequence of the current
sent by the first subscriber to the office and the hook g will be raised thus allowing
the annunciator f to drop freely down. The switchman now introduces a plug s
(in the case illustrated in Fig. 1, one of the pair 1) which is ready at hand into the
contact while at the same time pushing the bush 6 (Fig. 2) over the rings 3, 4
and 5, whereby the following actions take place; The contact between the collar
and the ring à causes the current from the test battery p to flow through the
auxiliary coils whereby the annunciator is raised; this current passing further
through the telephone and the rings 5, thence proceeding to the ring 4 through
the bush 6 and returning through the auxiliary coils of the contact valve e to the
battery p whereby the closing device e which is down or open when not in use is
attracted; furthermore the telephone t is connected with the circuit of the
calling subscriber through the rings 5 and 3 and by the aid of the bush or sleeve 6
so that the switchman can speak with the said subscriber.
the subscriber to be called has been received (in this case No. 2) the bush 6 is first
After the number of
released whereby the telephone is disconnected and the current passing through
the auxiliary coils of the closing device e is broken, whereupon the test rod 8 of
the plugs (of the pin 1) is brought into contact with the ring of the called for
subscriber.
Should the circuit of the latter be engaged, the pole of the test battery
which is furthest from the plug switches bears through the bush 10 of the inserted
plugs against the rings 2 of the circuit and a current passes from the contact
ring to the telephone and by the aid of the circuit connecting the latter with the
test battery on to the other pole thereof whereby the switchman hears a crepitating
noise in the telephone. But if on the contrary the circuit is disengaged this
noise is not heard and the plug is inserted through the contact rings into the
contact, while the bush 14 (Fig. 3) is pushed on in order to establish a connection
between the rings 11, and 12 and to cause the circuit of the subscriber called for
to be suitably connected to the call battery so that a call bell may summon the
last subscriber to the telephone. The circuit remains broken for the switchman 5
and hence for the calling subscriber until the former pushes the bush 14 forward.
By releasing the same the connection to the rear is re-established by the automatic

page_text: When the
withdrawal of the bush 14, and that with the call battery is broken.
conversation is ended one of the two communicants produces, by means of a call
bell the magnetic excitement of the coils e' of the closing device or flap whereby
the armature dis attracted, the hook n is raised and the device c is free to drop, after
which the plug (of the I pair) is removed.
The plugs shewn in Figs. 2 and 3 may be so far modified in their construction as
circumstances may require, and may have no part of their handle connected with
the circuits.
For this purpose the plugs are constructed as shewn in Figs. 4 and 5 wherein the
rings 3, 4 and 5 which in the above described arrangement were mounted on the
switch handle are now mounted on the front part of the plug in the place of
the contact pin or core. To facilitate comparison the parts which fulfill the same
purpose are marked in Figs. 4 and 5 with the same figures as in Figs. 2 and 3
Fig. 4 corresponding to the plug s¹. When in use the latter is inserted in the
contact until the sleeve 16 hears against the flange of the plug handle, in this
position the pawl which assumes the form of a spring 6 consisting of three parts
connects by means of this spring 6 the rings 3, 4 and 5, whereby the telephone t of
the switchman is intercalated in the subscribers' circuit and the closing device c is
attached moreover the ring 2 which is brought into play in lieu of the collar 2
completes the plug switch circuit and causes the annunciator to be attached.
When releasing the plug the spiral spring 7 draws the same back automatically a
sufficient distance to the rear to leave the ring 3 in contact with the spring 6 and
thereby with the subscribers' circuit, there is moreover formed a circuit between
the ring 2 and the ring h. Fig. 5 corresponds to the plug switch when the latter
is inserted as far as possible into the contact the foremost contact of spring 14
touching the ring 12. while the other two contacts of the said spring 14 bear upon
the insulated part of the plug core; a call bell current starts from the ring 12 and
passes through the spring 14 on its way to the subscriber's circuit.
The ring 10 is connected to the plug ring h. When the plug switch is released,
the spring 15 withdraws it automatically with the ring 11 is connected with the
third contact of the spring 14, the call bell current being now broken.
To test whether the line is engaged or not the plug ring his brought in contact
with the test rod 8.
Should the above described installation be applied to switch frames or cabinets
actuated by a single cord arrangement, only one plug of the construction shewn in
Figs. 3 or 5 would be required with the only difference that the metallic sleeve 18
at the lower end of the plug handle is connected through the ring 11 or 13, with
the plug switch or subscriber's circuit.
The diagram of Fig. 6 illustrates one of these arrangements, 11 12 are two
subscriber's circuits which pass through the contact or and through the coils w¹
of the electro-magnet of the corresponding annunciator in order to be led to earth.
To make the necessary connections, the plugs I, II, are used and form the ends of
the subscriber's circuits, bearing on the springs by means of the metal rings 18.
These springs rest upon terminals which are connected to earth. The springs b
can be depressed by the plug so as to release them from earth and allow them to
bear against the terminals t, 2 connected with the attendant's telephone t whereby
the latter is connected to the circuit of the depressed plug. Upon the underside of
the spring and insulated therefrom is arranged a contact plate which when
depressed comes to bear against the terminals p', m', p², m².
As the terminals, p³, are connected to the pole of the test battery which is
facing the plug, and the terminals m, m' are connected with the other pule of the
same battery while passing through the additional coil w² of the corresponding
magnet of the annunciator as soon as the spring is depressed the additional
coil w² is excited and attracts the valve or annunciator /.
To connect two subscribers the following manipulation takes place: As soon as
the annunciator of the subscribers circuit falls, the corresponding plug I is
depressed, whereby the earth connection o' is released while on the contrary the

page_text: terminals pm are placed by the small contact plate below the spring in circuit
with the additional coils w² and the test battery p, the valve being raised. At
the same time the telephone t of the attendant, is intercalated in the subscriber's
circuit through the contact plate t¹, the spring band the metal ring 18 and the
caller is communicated with. After the latter has indicated the subscriber with
whom he requires to be put in communication, his circuit is tested to find out if it
is not engaged by forming a contact between the test pin of the plug and the plug
ring.
Should the subscriber's circuit 12 (in this case that of the required subscriber)
be in use, the pole of the test battery p facing the plug will be connected to the
sheath of the circuit 2 through the ring 10 of the inserted plug and a current
will pass from the ring in contact h² through the telephone and through the circuit
connecting the same to the test battery on to the other pole of the latter, so that
the attendant hears a grating noise in the telephone. But if on the contrary the
circuit is free as shown in the figure this noise is not heard.
The plug is now inserted into the corresponding contact whereby the call is
heard by the subscriber required to be connected. Against the attendant i.e. the
calling subscriber. The circuit is broken between the attendant and the calling
subscriber so long as the former presses the ring 14 forward, but when this ring is
released the connection is automatically established in a rearward direction through
the return of the ring 14 whilst the connection with the call battery is broken.
When the conversation is ended one of the communicants, causes the annunciator f
of the calling subscriber to fall by reason of. its additional coils being without
current, whereupon the attendant severs the connection by withdrawing the
plug I.
When the above described arrangement is applied to switch cases having double
circuits, the current travels in the manner shown in Fig. 7. Instead of an earth
connection there is a return circuit and in order to connect two subscribers the
following manipulation takes place. Should for instance subscriber 1 wish to speak
to subscriber 2, the armature a of the former's annunciator will be attracted in con-
sequence of the call current sent off by him to the office, whereby the anounciator f
is allowed to fall. The attendant now inserts one of the free plugs s¹ (that of
pair in the case shown in Fig. 7) in the contact ring of the to and fro
circuit and pushes at the same time the ring 6 over the rings 3, 4 and 5, (see the
plug of Fig. 2) causing the following actions to take place that is to say: In
consequence of the contact between the ring 2 and the plug ring the circuit
from the test battery to the corresponding coil ³ is closed and the annunciator fis
raised. The circuit from the battery p to the telephone, the ring 5, the ring 4
(by means of the ring 6) and thence back to battery through the coil e² of the
closing device c being now likewise closed, the latter device which was open or
had fallen before is now attracted, moreover the telephone t is connected to the
circuit of the calling subscriber through the rings 5, 3 and 6. After giving out
the number of the subscriber required to be called (No. 2 in the present case) the
ring 6 is first released whereby the telephone t is thrown out of the circuit. The
testing pin 8 of the plug 2 (I pair) is now used to find out if the circuit is free.
Should it be so, the plug o2 is inserted in the ring and the terminal, and the
ring 14 (of the plug shown in Fig. 3) is shifted in order to connect the rings 11
and 12, whereby the circuit of the subscriber required is connected to the call
battery and a bell indicates such occurrence at the telephone. The circuit will
remain broken hetween the attendant and the calling subscriber so long as the
former presses the ring 14 forward but on releasing this ring the rearward con-
nection due to the retrogradation of the ring 14 is automatically established while
the connection with the call battery is severed. Reference must now be made to
an installation suitable for parallel circuits and consisting in the shunts which
when two circuits are connected together from the plugs through the coil w' of the
electro-magnets, being automatically broken during the connection, by the switch n
connected with the annunciator f.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. A telephonic installation wherein all the manipulations necessary for making
and breaking the connections between two subscribers are exclusively carried on by
means of plugs this installation having the following characteristic features: The
connection with the plugs for switching purposes, of devices partly fixed (Figs. 1
and 7) and partly loose (Fig. 6) whereby the switching operations are solely and
simultaneously effected by means of the plug without any previous preparation;
the arrangement of an auxiliary circuit with a battery p wherein one pole of the
latter is connected with a partial shunting through the auxiliary coils e² of the
contact valve, to the metallic plug, collars or rings 2 and 10 as well as to
the switches of the telephone t of the switchman while the other pole is connected
to the last named telephone as well as to the contact rings of the switch contacts
through the auxiliary coils w² of the call valve, in such a manner that according to
the manipulation of the plug required for establishing the connections the fallen
valves are automatically raised: the connection of the binding screw of the
telephone of the switchman which is furthest from the battery p, with the test
rod of the plug 82 serving for the connection of the called for subscriber.
2. The modification of the installation claimed above with the use of plugs
(Figs. 2 and 3) in which devices are mounted on the switch handle whereby are
effected the necessary switching operations for connecting and disconnecting the
telephones of the switchman for raising fallen valves and for producing alarms.
3. A modification of the installation mentioned in Claim with the use of plugs
(Figs. 4 and 5) where the switching mentioned in Claim, 2, are mounted on the
plug core and the contacts consists of several springs.
4. The application of the installation described in Claim 1 to telephonic switch
cases, wherein the contact valve is in a parallel circuit with the call valve of the
connected subscribers and the use of an automatic breaking of the shuut of the
subscriber's circuit containing the call valve.
Dated the 4th day of August 1894.
HUGHES, ELI & HUGHES,
76 Chancery Lane, W.C., Agents for Applicant.