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Патент USA US2136620

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Nev. 15, 1938.
GJV. KING
2,136,620
TELEPHONE SYSTEM
Filed June 21, 1935
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INVENTOR
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'Filed June 21, 1935
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Nov. 15, 1938.
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2,136,620
TELEPHONE SYSTEM‘
Filed June 21, 1935
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Nov. 15, 1938.‘
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G. V. KING
TELEPHONE SYSTEM
Filed June 21, 1935
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Filed June 21. ‘1935
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Nov. 15, 193.
G. V. KING
2,136,620
TELEPHONE SYSTEM
Filed June 21, 1935
ll Sheets-Sheet 7
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Nov. 15, 1938.
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Filed June 21, 1935
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TELEPHONE SYSTEM
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Nov.’ 15, 1938.
G v, KING
2,136,620
TELEPHONE SYSTEM
Filed June'2l, 1935
11 Sheets-sheaf, 9
INVENTOR
BY
G. l/. KING
waeem'w
ATTORNEY
Nov. 15, 1938.
G. v. KING
2,136,520
TELEPHONE SYSTEM
Filed June 21, 1935
‘ll Sheets-Sheet 10
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A 7' TORNE V
Nov. 15, 1938.
a. v. KING
2,136,620
TELEPHONE SYSTEM
Filed Juné 21, 1955
ll Sheets-Sheet ll
xvi W3
INVENTOR
By
a. l/. K/‘NG
696M
A T TOR/V5 V
Patented Nov. 15, 1938
2,136,626
UNlTED STATES PATENT OFFICE
2,136,620
TELEPHONE SYSTEM
Gerald V. King, Chatham,'N. J., assignor to Bell
Telephone Laboratories Incorporated, New
York, N. Y., a corporation of New York
Application June 21, 1935, Serial No. 27,675
9 Claims. (Cl. 179——18)
This invention relates to telephone systems arrangement between lines, links, and switching
and particularly to systems involving the use of
automatic equipment for establishing conversa
tional connections.
The object of the invention is to improve small
automatic telephone systems, such as satellite
systems, by performing the various local and in
terof?ce switching connections with a unitary
and compact arrangement of switch structure
10* and circuits.
units contemplated by the invention.
'
Before discussing the details of operation, at
tention is directed to Fig. 12. In this layout of
three cross-bar switching ‘units, identi?ed as
frames 1, 2 and 3, twenty ‘lines are shown, ten
on frame 1 and ten on frame 2.
Ordinarily,
each frame iscapable of holding ?ve links, each
of which can be connected to any two lines on
different horizontal levels through the appropri
ate cross-points. On the other hand, if the ca- ,
pacity of the exchange is greater than ten lines,
say twenty lines, and the traflic originating from
A feature of the invention is the use of a cross
bar switch unit per group of local lines which
combines in a single structure the functions of
a line ?nder and a connector in relation to a
155 group of links common to all switching units.
said lines does not warrant the use of more than
?ve links, the additional ten lines can be located
Each switch unit is provided with horizontal line
on a second frame, as for instance on frame 2,
contacts and vertical link contacts coordinated in
and the ?ve links accessible to frame 1 can be
relation to each other into one cross-point Where
by the operation of one horizontal and one ver
extended so as to be available to the additional
ten lines on frame 2. In this manner, the num
20. tical magnet in the proper combination closes
ber of lines which can be included in one ex
' said contacts or cross-point of a calling line
29,
through an allotted link, and the operation of
another horizontal and vertical magnet in proper
combination closes the de?ning cross-point of
the called line or outgoing trunk through said
allotted link. All the lines in each switching ,
unit are accessible to one end of all the common
links when calling and all the lines and trunks
are accessible to the other end of said links when
30 said lines or trunks are called.
Another feature of the invention resides in the
allocation of a plurality of cross-points on one
or more of said switch units for the use of out
going trunks which may extend to a main central
35, office and which may be reached by a calling
subscriber by dialing a predetermined digit which‘
serves to extend his connection to the trunk
cross-point level and to the operated cross-points
of an idle trunk in that level.
40
The nature of the invention will be more clear
ly understood from the following description of
one embodiment thereof and of possible modi?
cations thereto with reference to the accompany
45
ing drawings in which;
Figs. 1 to 10, inclusive, when arranged as shown
in Fig. 13, disclose a number of link circuits ac
cessible to groups of subscribers’ lines and trunks
shown in Figs. 2 and 6 for the purpose of com
50 pleting connections between said lines or between
change unit limited to ?ve links can be extended,
in groups of ten, almost inde?nitely, although the
circuits of the present invention, being designed
primarily for application in rural districts, limits
the total number of lines to a maximum of ?fty
lines, that is ?ve switching units of ten lines each.
Moreover, while the number of lines can be
increased with respect to a de?nite number of
links, conversely, my invention makes it possible
to increase the number of links with respect to
a de?nite number of lines. If, for instance, the
quantity of tra?ic which originates in an ex
change of twenty lines is greater than that which
can be handled successfully by five links and two
additional links are needed, said links may be
accommodated on a separate or third switching
unit to one half of whose horizontal cross-points
may be multipled the lines from the ?rst switch
ing unit and to the other half the lines from the
second switching" unit with the two links extend 40
ing‘to both halves of the third switching unit.
In Fig. 12, an exchange of twenty lines is illus
trated as needing seven links to handle the tra?ic
successfully. Consequently a third switching
.unit is supplied, frame 3, to the left half of 45
whose horizontal cross-points the lines appearing
on frame 1 are extended and to the right half of
whose horizontal cross-points the lines appearing
on frame 2 are extended and the two additional
links, namely, links 6 and ‘7 are extended to both
said lines and trunks;
' halves of frame 3. Obviously, if ten links were
Fig. 11, arranged below Fig. 10, as shown in needed to serve the twenty lines, then a fourth
Fig. 13‘, is the timing, ringing and alarm circuit switching unit would be required and the third
and fourth switching units could be arranged so
which serves all links;
Fig. 12 is a diagrammatic presentation of the that the lines appearing on frame 1 would ex 55
2
2,136,620
tend clear across frame 3 and the lines appearing
on frame 2 would extend clear across frame 4
with the ?ve additional links accessible to each
of the twenty lines through frames 3 and 4.
Inasmuch as the preferred embodiment of this
invention is disclosed with respect to its appli
cation to a rural telephone system in which a
plurality of telephone stations may be located in
the same pair of line conductors, as for instance,
10 ?ve stations on the tip and ?ve stations on the
ring, and which makes it necessary to provide
“code” ringing to identify each station and to
seven links are provided for twenty lines, an ad
ditional frame (frame 3) is split in two and the
two additional links accommodated thereon as
already described.
Under such circumstances,
when a subscriber, such as subscriber 624, initi
ates a call and the selecting magnet 2I2, on the
main frame for the horizontal level of the calling
line is operated, it also becomes necessary to
operate the selecting magnet for the same level
on the additional frame since the idle link to be 10
selected and attached to the calling line may be
either in the main frame or the auxiliary frame.
tween a station on one line and a station on an
In the drawings, Fig. 4 represents the auxiliary
frame, while its selecting magnets 306 to 3I0 are
shown on Fig. 3 and of which selecting magnet 15
309‘controls the continuation, on the auxiliary
frame, of the level controlled by selecting mag
other line, (2) a connection between two stations
net 2I2 on the main frame.
on the same line and (3) a connection between a
relay I04 operates, it completes a circuit which
extends from ground through its contacts, con 20
ductor I06, conductor GIT right contacts of mag
net 2I2, conductor 2I8, right winding of selective
magnet 309 to battery and ground. Magnet 309
operates and then extends its operating ground
make it possible for one station to call another
station on the same line, the more detailed de
15 scription of this invention will include the opera
tions required to (1) establish a connection be
20 station and an outgoing trunk, three of which
occupy the ?rst three horizontal cross-points,
respectively, on frame 1 and the left half of
frame 3.
It must be understood, however, that the in
Consequently when
25 vention herein set forth and claimed is not limited
through its right contacts, conductor 3II,_top 25
to any such arrangement but can be readily ap
plied by any one skilled in the art to an exchange
having individual lines or to any other arrange
ment of lines and stations that suggest themselves
30 by the character of the service to be rendered as,
for instance, two or four party line service or
outer contacts of relay 208, winding of relay 2I9
to battery and ground. Relay 2I9 operates and
completes a circuit for relay I008, which circuit
single party service.
When any one of the group of subscribers in
the group shown in Fig. 6, say subscriber 624,
36 initiates a call, line relay B00 is operated over a
circuit extending from grounded battery through
the left winding of said relay, outer contacts of
cut-off relay 60I, the subscriber’s line loop, inner
contacts of relay 60I, right winding of relay 600
40 to ground. Relay 600 operates and completes a
circuit for selective magnet 2I2 which extends
from ground through the contacts of relay 600,
left back contacts of relay 602, conductor 633,
upper No. 4 contact-set of relay 206, conductor
2I4, right winding of selective magnet 2I2, con
ductor 2I5, lower normal contacts of relay 20B,
conductor 2I6, left contacts of relay I02, right
outer contacts of relay I03, right contacts of re
lay IOI, to battery and ground. Magnet 2I2 op
60 erates and locks in a circuit completed from op
erating ground as traced to its left winding,
through its left front contacts, left back contacts
of selective magnets 2II, 2I0 and 209, conductor
2", winding of relay I02, right inner contacts of
55 relay I03, right contacts of relay IN, to battery
and ground. Relay I02 operates in the locking
circuit of magnet 2I2, closes an obvious circuit
for slow-operate relay I04 over its right front
‘contacts and opens the operating circuit of mag
60 net 2I2 at its left contacts.
In the usual construction of the cross-bar
switch, the so-called “100 point” switch prefer
extends from ground on the left contacts of relay
2I9, conductor 224, left normal contacts of link 30
make-busy key ‘III, left back contacts of relay
‘H01, (if the ?rst link is idle), conductor ‘H2, No.
8 contact-set of relay I0I51, winding of relay
I008, to battery and ground. Relay I008 operates
and, through its right sets of contacts, connects
ground to conductors 3I2 and 3I3 respectively,
the former of which extends to the operating
winding of the holding magnet 3001 on the cross
bar frame 1 while the latter extends to the op
erating winding of the holding magnet ‘1001 on 40
the lower cross-bar frame 2.
Inasmuch as the
calling line 624 appears in the upper frame and
the origination of the call therefrom has resulted
in the operation of relay 2 I9, the circuit of hold
ing magnet 3001 of the ?rst link, if idle, is com 45
pleted over conductor 3| 2, winding of magnet
3001, conductor 320, right contacts of relay' 2I9
to battery and ground. Magnet 3001 operates,
looks from battery through its lower winding and
contacts, conductor 3I5, right back contact of 50
relay IOI0, conductor IOI6 to ground over the
No. 2 contacts of relay IOI5’ and, since hori
zontal selecting magnet 2I2 is also operated, the
combination of the operated selecting magnet 2I2
and the operated holding magnet 3001 serves to 55
operate contact-set 3| 4 on the ?rst link and there
by extend conductors 609, SH and (H2 of the
calling line 624 to the ?rst link.
As soon as
cross-point 3I4 is operated, then, by virtue of
succeeding operations in the link which result in 60
the operation of relay I0I51, as described herein
after, a circuit is completed for relay 602 which
extends from ground and battery, through the
right winding of said relay, conductor 6I2, third
ably has one selecting magnet for ten horizontal
cross-points, thus making it possible to provide
65 ?ve links to the frame, each link having one I' set of contacts on cross-point 3I4, conductor 65
“calling” cross-point and one “called” cross
IOI6, to ground on the No. 2 contact-set of relay
point; that is, one set of contacts through which I0I51. Relay 602 operates and performs func
the link gains access to the calling line and an
tions described hereinafter.
other set of contacts through which it gains ac
If the calling line had been located on frame 2,
70 cess to the called line. However, where the link and in the corresponding fourth horizontal posi
capacity is greater than ?ve, and other switch tion on the frame as line 624 is located on frame
frames have to be provided to accommodate ad
1, say line 634 (not shown), with its extension to
ditional links, the number of frames is, of course, the fourth horizontal position on the right of
determined by the number of links. Where, as in frame 3, then after the operation of the proper
the case being illustrated according to Fig. 12, selecting magnet on frame 2, instead of closing 75
3.
2,136,620
the circuit of holding magnet 3001, the circuit
of holding magnet ‘I001 on frame 2 would have
been completed from ground and battery
through the right contacts of relay 606, con
ductor 628, upper winding of holding magnet
T601, conductor 3 I3, right inner contacts of‘ relay
H108 to ground. In this way, only the holding
magnet of the ‘chosen link in the frame in which
the calling line belongs is operated.
10
Before proceeding with the further operations
Should the ?rst link be busy, this condition
causes the mechanical locking of relay ‘H01 in
the
manner
described
hereinafter,
and
the
ground connected to conductor 224 is advanced
over the left front contact of relay ‘H01, back
contact of relay ‘H02 of the second link, if idle,
ing line, it is necessary to observe those circuit
operations which, prior to this connection, take
the No. 8 contact-set of relay I0I52 of said link,
to the winding of the start relay corresponding 10
to relay I003 in said second link. Further, if the
second link is also busy and, therefore, relay ‘H02
is mechanically locked in an operated position,
place to insure that, in the event that more than
the ground on conductor 224 is advanced over the
which follow the connection of a link to the call
15 one line calls at the same time, links, if avail
able, are connected to each of said lines in a de?~
nite order of preference and only after each link
has been connected; to a line.
Suppose that subscriber 624, whose line ac
cording to Fig. 12, is located on cross-bar frame
1 and on the fourth level thereof and that sub~
scriber 63L whose line appears on cross-bar
frame 2 and on the ?rst level thereof, simultane
ously initiate calls by removing their respective
25 receivers off their hooks, line 624 will cause the
operation of line relay 600 as already described
while line 63H will cause the operation of line re~
lay ?IZ by the closure of an obvious circuit simi
lar to that for line relay 600.
It will be recalled that the operation of relay
690 resulted in the operation of horizontal se
lecting magnets H2 and 309 controlling those
36
operations already described, the ?rst link, if idle,
becomes attached, therefore, to line 624.
cross-points on the link frames to which the line
I524 is extended. In a similar manner, the oper
ation of relay EH2 causes the operation of hori
zontal selecting magnets 601 and 306 of those
cross-points in the link frames to which line 63I
extends. Accordingly, when relay 6I2 operates,
a circuit is completed which extends from. ground
left front contact of relay ‘H02 to the armature 15
of relay "H03 (not shown) in the third link and
from thence either over the back contact of this
relay, if the link is idle or over the front contact
if the link is busy, to the contacts of relay ‘H04
(not shown) of the fourth link; the circuit path
being extended over an operated relay ‘H0 in
each busy link until an idle one is found, after
which operations will take place similar to those
already described. Should all links be busy at
the time a subscriber initiates a call, relay ‘H0
in each link will be locked in an operated posi
tion, whereupon a circuit is completed which ex
tends from ground on the right front contacts
of each relay ‘I'Iil up to and including relay ‘H07
of the seventh link, conductor 80I, winding of
relay N16, to ground and battery. Relay I00 op~
erates and closes an obvious circuit for relay IOI
which operates and opens the battery connec
tion to the operating circuits of the horizontal
selecting magnets, thus making it impossible to
operate any of them if no link is available. Re
lay IOI further completes a circuit which extends
from ground through its left contacts, conductor
I07, winding of magnets 1091-1097 in parallel, to
Each of these magnets op
erates and unlocks its companion relay 1 I 014097.
on the contacts of relay BI2, left normal contacts ' battery and ground.
of relay 6M, conductor BIS, No. I contact set of
relay 603, right winding of selective magnet 60?,
left normal contacts of relay 605, conductor EIE,
So long as each of the ‘links is busy, then, inas
much as relay I008 in each of said links releases
conductor 2I6, left contacts of relay I02, right
immediately after the horizontal selecting mag
45 outer contacts of relay I03, right contacts of re
nets are operated, as more completely described
lay IilI, to battery and ground. It will be re
called that the circuit of horizontal selecting
magnet 2 I2 was similarly completed to conductor
2m and thence to battery and ground on the
50 back contacts of relay IOI. Assuming that the
circuit of each of the selective magnets 2I2 and
hereinafter, each of the separate make-busy re
lays ‘HUI-‘Hi17 will remain operated over a path
till is closed simultaneously then, when. magnet
60'! operates, a circuit path is partially completed
for selective magnet 306 which extends from
55 ground and ‘battery through its left winding, con
which, for relay H01, extends from ground and
battery through its right winding, conductor ‘I08,
left contacts of relay I006, No. 2 contact-set of
relay “M51 to ground; relay I0I5l in each of the
busy links having been operated as described
hereinafter. On the other hand, as soon as a
link becomes idle, relay I0I51 releases, the cor
responding make-busy relay ‘II 01 releases and the
‘
ductor 3 I1, right contacts'of magnet 601, conduc
tor GI'I, conductor Ill?, to the contact of relay
I64. However, each of the selecting magnets 2I2
and Gill, on operating, closes a locking path
60 through their respective left windings and front
contacts, the left back contacts of the selecting
magnet immediately ahead of them, in prefer‘
ence, to conductor 2|‘! and thence to battery and
ground on the back contacts of relay IOI through
link is made available for service.
65 the winding of relay I02. Inasmuch as the oper
tion that said subscriber has started the call at
the same time as the subscriber on line 624, and
assuming that, due to the preferential arrange
ment of line 624 ahead of line 63 I, a link has been
connected to line 624, it will be recalled that the:
horizontal selecting magnets 601 and 306, cor 70
responding to the position of line 63I on the
link frames, could not remain operated once the
locking circuit‘ of magnet Bill was opened by the
ation'of magnet 212, which is ahead of magnet
5431, by opening its back contacts breaks the lock
ing path of magnet 691, only magnet 2I2 whose
locking path is not broken, can lock. Hence,
70 when relay I02 operates as before described, the
operating circuit of magnets 60'! and 2I2 is
opened at its back contacts and since magnet
75
2 I2 is now locked and magnet 60] is not, magnet
Bill releases and further opens the previously de
scribed path for magnet 306.
In virtue of the
Also, when a
link becomes idle and its make-busy relay H0
releases, the circuit of relay I06 is broken, caus
ing the release of relay ml, the consequent re
lease of all locking magnets 'IEl91—'I097 and the
restoration of battery to the start circuit of the
horizontal selecting magnets.
Returning, now, to the allotment of an idle
link to the subscriber on line 63I on the assump
operation of magnet 3I2.
However, as soon as
the link is allotted to line 624 and relay 602 has 16
4
2,136,620
ductor GIZ, whereupon line relay 600 releases and
paths to the various relays shown in Figs. 5 and
9, as explained hereinafter; (5) over its No. 5
contact-set, ground is connected to conductor
I02I which, over the right middle contacts of
opens the locking circuit of horizontal selecting
relay 9| I, extends as conductor M4 to resistance
operated, cut-01f relay 00I operates over a circuit
completed through the right locking contact of
relay 602 to a previously traced ground on con~
magnet 2I2 the release of which, in turn, opens
the locking circuit of the corresponding selecting
magnet 309 on the third link frame. Once the
locking circuit of the horizontal magnet 2I2 is
10. opened, relay I02 releases and restores the op
erating and locking battery for all of the hori
zontal selecting magnets. The horizontal magnet
60? and also consequently, horizontal magnet 306
can now operate and lock and cause the allot
I5. ment of an idle link to line 63L
Having shown how each one of two idle links
may be connected to each one of two calling lines
on which calls are initiated simultaneously, the
operations which follow the connection of the
?rst link to a line on which a subscriher’s sta
tion, say station 624, is located, will now be de
scribed. It will be assumed that the subscriber
II32, contacts of relay II2I, left winding of relay
I I2I to battery and ground. Relay I I2I operates
over this self-interrupted circuit and induces cur
rents at each interruption in the closed inductive
path extending from ground through the right 10
winding of relay II2I, right winding of coil II3I
to ground. Inasmuch as the left winding of said
coil comprises an element in the circuit of relays
I M2 and IOI3, which circuit extends over the
subscriber’s loop, said interruptions are repeated 15
over said loop as “dial tone” which is heard by
the subscriber as an instruction that he may pro
ceed to dial the wanted number; (6) over the No.
6 contact-set of relay I0I51 a circuit is completed
over the left outer contacts of relay I009 and con ,20
ductor I 023 through the left winding of relay I I00
to battery and ground, which relay functions
624 wishes to establish a connection with another
are described hereinafter; (7) over its No. ‘I con
subscriber’s station, say station 63I whose line,
according to Fig. 12, is located on the ?rst hori
zontal level of frame 2 and that, in order to es
tablish said connection, subscriber 624 dials the
number 319. The ?rst two digits of this number
identify the position of the line on the frame
on which it is located while the last digit identi
?es the ringing code assigned to station 63L
When the cross-point 3I4 is closed, a circuit is
completed for relays IOI2, IOI3 and IOI4 over
the line loop which may be traced from ground
tact-set, relay I0I51 closes a partial path for
relay IOII which extends from battery through 25
and battery through the winding of relay IOI2,
bottom outer back contacts of relay IO0I, bottom
outer contacts of relay I000, conductor IOIl, sec
ond contact from the top of cross-point 3I4, con
ductor 6II, loop of subscriber’s line 024, con
40 ductor 609, top contact of cross-point 3“, con
ductor 3I6, top outer back contacts of relay I000,
top outer contacts of relay IO0I, winding of relay
IOI3, conductor IOI8, left normal contacts of
relay III I, left normal contacts of relay 906, con
ductor 9I5, left winding of transformer I I3I to
ground. Relays IOI2 and IOI3 operate closing
obvious parallel circuits to the winding of relay
i0“ which operates. Relay IOI4 causes the op
eration of relay I0I51 which, on operating con
nects: (1) ground through its No. I contact-set
to conductor IOI9 which extends to the No. I
contact-set of relay I0I52 of the second link and
‘ from thence through corresponding contact sets
of relay I0I53~I0I57 of all'the seven links, from
the last relay of which, that is relay I0I57, it ex
tends by way of conductor 800, to the winding
of register I05 which, on the other side of its
winding, is connected to battery and ground. If,
when the ?rst link is taken into use, as above
described, and relay I 0 I 51 operates, the remaining
six links are busy, each of their corresponding
relays IOI5 is operated and the circuit to register
I 05. is completed to indicate an all-busy condition
of the links; (2) through its No. 2 contact-set,
~ relay I0I51 connects ground to conductor IOI6
which completes previously described circuits to
the right winding of relay 602 and to the locking
winding of holding magnet 3001; (3) over its
No. 3 contact-set relay I0II‘i1 extends ground
through the bottom inner back contacts of relay
IBIH and thence to the No. 4 contact of relay
i009; (4) over its No. 4 contact-set ground is
connected to conductor I020 and, through the
bottom outer contacts of relay I002, to conductor
' I020, both of which conductors provide locking
the winding of said relay, conductor I022, right
outer contacts of relay III I, conductor 9I3, No. ‘I
contact-set of relay I0I51, normal contacts of
relay IOII to conductor I02I.
The manner in
which conductor I02I is completed to ground will 30
become evident hereinafter from a consideration
of the operation of the miscellaneous signaling
circuits in Fig. 11, which begins to function as
soon as relay I I00 operates at the time ground is
connected to conductor I023; (8) over its No. 8 36
contact-set, relay I0I51 opens the previously de
scribed circuit of relay I008, causing said relay to
release. In releasing, relay I008 disconnects
ground from conductors 3I2 and 3I3 and, since
the holding magnet 3001 is now locked through 40
its lower winding, ground on these respective con
ductors is no longer necessary while over its left
contacts relay I008 completes a circuit for the
link make-busy relay ‘H01 which extends from
grounded battery through the right winding of 46
said relay, conductor ‘I08, left contacts of relay
I008, No. 2 contact-set of relay I0I51 to ground.
Relay ‘H01 is now held operated as long as the
link is busy.
Relay II00, on operating, looks over the right 60
winding and right inner contacts to ground on
conductor 9M, causes ground to be connected to
locking conductor I I33 which extends to various
parts of the circuit of Fig. 11, and further com
pletes a circuit for relay Hill which extends 65
from. ground on the left outer contacts of relay
H00, contacts of relay II03, winding of relay
Relay IIOI oper
IIOI to battery and ground.
ates and closes an obvious circuit for relay II02
which causes it to operate and to further close 60
an obvious circuit for relay H03. Relay II02
further completes a circuit for relay II I6 extend
ing from ground through its right contacts, con
ductor I I38, normal contacts of relay I I I6, wind 65
ing of relay III6, resistance H34 to battery and,
in parallel therewith through the left outer back
contacts of relay III5, resistance H35 to bat
tery. It will be observed that the winding of
relay III5 is short-circuited by the operating
ground for relay III6 by the connection of said
ground to one side of its winding at its left outer
back contacts and to the other side of its wind
ing at the normal contacts of relay III6. Relay
III6 operates, locks to ground on conductor H33 75
5
2,136,620
and maintains the short circuit for the winding
.of relay IH5 through its front contacts.
In the meanwhile, the operation of relay H03
opens the circuit of relay IIIlI which, after an
extending over a previously traced path to. the
relay H02 which releases after an interval and
left inner front contacts of relay I I M, then, when
said relay releases, the short circuit is removed
in turn, opening the circuit of relay H03 which
and relay III3 operates over a circuit which
also releases after an interval and» reestablishes
extends from grounded battery, resistance IM'I,
the circuit for relay HOI to repeat the cycle of
left inner front contacts of relay I I I8 to ground
Relay
H02, on releasing, further disconnects ground
from the left terminal of relay III5 at the left
outer back contact of said relay, after which
said relay operates in a circuit which extends
from ground and battery, resistance H35, wind
ing of relay Hi5, front contacts of relay HIE to
ground on conductor H33. Relay IH5 operates
and establishes a circuit for relay III‘I extend
ing from ground on its right outer contacts, left
inner normal contacts of relay III'I, winding of
relay I I I1, resistance I I3‘! to battery and ground.
Relay HIT operates and establishes a short cir
cuit for the winding of relay HM by connecting
ground on conductor H33 through its left inner
contacts to the left terminal of the winding of
said relay, ground having been already con
nected to its other terminal in a path extending
from ground on the right outer contacts of relay
HI5, right outer back contacts of relay IIM to
the right side of its winding.
On the next operation of relay H02 ground
is again connected to conductor II 38 and since
relay I I I5 is operated, said ground is extended to
20
25
30
resistance H34 thereby short-circuiting relay
I I I0 and causing it to release. Relay I I I5, how
ever, does not release since it is now held in an‘
operated position by the ground on conductor
H38 extended through the normal contacts of
relay HIE. On the subsequent release of relay
40 H02 and the removal of ground from conductor
H38, relay IH5 releases, the short-circuiting
ground for relay HM is disconnected and this
relay now operates in a circuit extending from
ground and battery ‘through resistance H36,
45 winding of relay I I I4, left inner contacts of relay
III] to ground on conductor H33.
Upon the next operation of relay H02, relay
IH6 operates again over a previously described
path, locks as before and again short—circuits
60 the winding of relay HI5.
When relay
releases, relay III5 operates in parallel with
relay HIS and establishes a short circuit for
relay III'I which circuit may be traced from
ground on the right outer contacts of relay II I5,
55 right front contacts of relay HM, resistance
H31. Relay III'I releases and completes a cir
cuit for relay HI8 which may be traced from
ground and battery, resistance H40, winding of
relay IH8, left inner normal contacts of relay
60 III8, left middle contacts of relay HI'I, left
inner front contacts of relay IIM to ground.
_ Relay III8 operates and establishes a short cir
cuit for relay H3 by connecting ground on con
ductor I I33 through its left inner front contacts
65 to the left terminal of the winding of relay I I I3
while ground is connected to the right terminal
of its winding through its own right back con
tacts, through the left middle contacts of relay
III‘! as already traced.
70
the winding of relay III3 is held short-circuited
by ground through its right back contact and
interval, releases, in turn opening the circuit of
10 operations ofrelays HOI, H02 and H03.
15
relay HI5, relay IIM'releases. Further, since
When relay H02 operates again, relay HIS
releases in the manner already described and,
when it releases, relay III5 also releases. Inas~
much as relay HM is held through the normal
contacts of relay HH and the right outer con
75 tacts of relay III5, then, with the release of
on conductor H33.
‘
10
Thus, after relay H02 has operated and re
leased four consecutive times, relays III3 and
III8 are operated and locked while the two pre
vious pairs of counting relays, namely HI5 and
HI6, HM and HH are released.
15
In the same Way it can be shown that after
eight consecutive operations and releases of relay
H02, relays III2 and HI9 will be operated and
locked; that after twelve consecutive operations,
relays I I i0 and H20 will be operated and locked, 20
that after twenty-four consecutive operations,
relays H09 and H05 will be operated and locked,
and that after forty-eight consecutive opera~
tions relays H09 and H05 will be released. In
all ‘cases, all preceding pairs of counting relays 25
will be ,released.
'
'
Thus in the circuit of Fig. 11, six pairs of
counting relays are provided which function to
count time through the operating cycle of relays
IIOI, H02 and H03, which cycle can be made as 30
long or as short as desired by appropriate means.
During the interval that a link is connected to
the calling line the counting relay circuit of
Fig. 11 provides the proper intervals for giving
the appropriate signals usually given when calls 35
are not completed in a given/length of time and
further provides for operating the ?ve ringing
relays .I I22-I I26,.inclusive, in the proper inter
val called for by the ringing code of each of ?ve
stations located ‘on each of the line conductors. 40'
Inasmuch as code ringing is well established in
the art and can be carried out by any Well-known
means which provides for the closure of the ring
ing circuit path in accordance with the code
called for by the Wanted station, it is not thought 45
necessary tounduly lengthen this speci?cation
by the detailed description of all the functions of
the circuit shown in Fig. 11 except in so far as
they are necessary to. a complete disclosure and
understanding of the operation of the link cir
cuit and the manner in which it is used to estab~
lish a talking connection between two stations.
60
Returning, now, to the operation of the link
circuit and the fact that the calling station has
been given dial tone, let it be assumed that the 55
subscriber does not dial for the time interval
measured from the instant relay H02 operates
to the time that relay II I0 operates. If the link
has not released during this interval, which
means among other things, that the subscriber 60
has not dialed, a circuit is completed over a pre
viously described path to conductor I02I and
thence over the inner right back contact of relay
H20 and the left front contact of relay HIO as
soon as the timing circuit has‘advanced to oper 65
ate relay HIO. Relay IOH operates, locks over
conductor I022, outer back contact of relay 9I I,
conductor 9I3, No. 1 contacts of relay I0I51 to
ground at its left front contacts and, over its
right contacts, extends the winding of relay IOI0 70
to conductor I024. When the timing circuit has
advanced, in the manner previously described, to
the point where relay H09 is operated and relay
H05 is released, ground is connected to conduc
tor‘ I024 over a path which extends through the 75
6
2,136,620‘
left front contacts of relay H09 and right con~
tacts of relay II05, causing the operation of
relay IOI0 which locks to ground over conductor
I022, right outer contacts of relay 9! I, conductor
9I3, No. ‘I’ contact-set of relay I0I51, left con
tacts of relay IOI I, ground. Relay IOI0 discon
nects ground from conductor 3I5 over which
holding magnet 3001 has locked. Magnet 3001
releases and frees the subscriber’s line at the
10 cross-bar contact-set 3I4. The restoration of
the link equipment to normal thereafter is the
same as that which will‘ be described subsequently
for the disconnection of a completed connection.
Now if the subscriber 024 still has his receiver
15 off the hook after the link is freed, or if the line
is crossed, the line relay 600 will reoperate over
the line loop since, with the release ‘of the cross
bar point, ground is disconnected from conductor
6 I2 causing the cut-off relay 60I to release, there~
201 by again connecting relay 600 over the line. Re
lay 602 being slow-release, does not release imme
diately and before it can release, the reoperation
of relay 600 will cause it to remain locked, which
condition will prevent the reconnection of the
25 ground to conductor 609 and thereby prevent the
seizure of another link during the time that the
line is locked out of service.
Assuming, however, that the subscriber does
not delay dialing until the operation of relay I0l0
but that, on hearing dial tone, proceeds to dial
the tens digit 3, then on the interruption of the
line which follows the ?rst pulse, relays IOI2 and
IOI3 release, but relay IOI4, being slow to release,
remains operated during pulse interruptions. A
circuit, therefore, is completed which extends
from ground on the left back contacts of relay
IOI3, left inner contacts of relay IOI4, conductor
I025, winding of relay 905 to battery and ground.
Relay 905 operates and closes an obvious circuit
40 for relay 904 which also operates. Another cir
cuit is also completed which extends from ground
through the No. 4 contact-set of relay I0I51, con
ductor I020, lower back contacts of relay I002,
conductor I026, backcontact of No. 4 contact-set
I of relay 9I0, conductor 9I6, right back contacts
of relay IOI3, conductor I021, left back contacts
of relay 90I, contacts of relay 902, winding of
relay 903 to battery and ground. Relay 903 op
erates and the ground through the left back con
. tacts of relay 90I is now extended through the left
inner contacts of relay 903 to one side of the
right winding of relay 90I, the other side of which
is also connected to ground through the left front
contacts of relay 994. Relay 903 further com
pletes a circuit for relay 50I which extends from
ground through the right front contacts of relay
903, left back contacts of relay 900, conductor 9I'I,
winding of relay 50I to battery and ground. Re
lay 50I operates but performs no useful function
60 at this time.
When relay IOI3 reoperates on the closure of
the line after the interruption thereof by the ?rst
pulse, the circuit which caused the operation of
relay 903 is opened while neither relays 905 nor
65 904 release during the pulse interruption since
both of them have slow releasing characteristics.
Moreover, and due to the fact that relay 904 does
not release, relay 903 does not release either, but
holds in a circuit which extends from ground
70 through the left front contacts of relay 904, right
winding of relay 90!, left inner contacts of relay
903, contacts of relay 902, winding of relay 903 to
battery and ground. Relay 90I operates in this
locking circuit and, on operating, extends ground
75 to conductor 9 I8 which looks relay 50I through its
top inner contacts, closes an obvious circuit for
relay 900 through the left winding of said relay,
causing the operation of said relay which further
locks over its right winding and right outer con
tact to ground on the left front contacts of relay
904.
When the line is opened again by the inter~
ruption of the second pulse and relay IOI3 conse
quently releases, the ground previously traced
through the right back contacts of relay I 0I3,
left armature of relay 90I to conductor I021, is
now extended over the left front contacts and left
winding of relay 90I, winding of relay 902 to bat
tery and ground, causing relay 902 to operate,
whereupon relay 903 releases and relays 90I and j
902 hold in the circuit of relay 902 just traced.
With relay 993 released, a circuit is completed for
relay 502 which extends from ground on the
right back contacts of relay 903, conductor 9I9,
top outer contacts of relay 50I, winding of relay
502 to battery and ground. Relay 592 operates
and completes I a circuit which
extends
from
ground through the right outer front contacts
of relay 905, conductor 92!, top outer contacts
of relay 502, conductor 5I9, normal contacts of
relay 909, winding of relay 909, resistance 922, to
battery and ground. Relay 909 operates while re
lay 908 remains short-circuited by ground on the
battery side of its winding extended thereto over
conductor 5I9. On the reoperation of relay !0I3 30
following the closure of the line on the termina
tion of the second pulse, the holding circuit for
relays SM and 902 is opened causing said relays
to release, but relay 900 being locked to ground
on the contacts of relay 904, which relay does not -
release during the transmission of the pulses
of a digit, remains locked, whereupon relay 50I
is released by the opening of the contacts of
relay SM and relay 502 is locked in a circuit
which extends from ground and battery through 40
the winding of relay 502, top inner contacts of
said relay, conductor 5I8, left outer back con
tacts of relay 903, right inner contacts of relay 900
to ground on the left front contacts of relay 904.
On the release of relay I9I3 when the line is
opened by the interruption of the third pulse, relay
903 operates again as it did for the interruption
of the ?rst pulse, and since relay 900 is operated
at this time, a circuit is completed for relay 503
which extends from ground through the right
front contacts of relay 903, left front contacts‘
of relay 900, conductor 920, top middle contacts
of relay 502, winding of relay 503 to battery and
ground. Relay 503 operates. On the reopera
tion of the relay IOI 3 when the line is closed after
the third pulse, relay 90I operates while relay 992
does not as before described. However, since the
third pulse is the last of the series of pulses for
the ?rst digit 3, no more pulses will be forthcom
ing for the interval required by the subscriber to 60
wind up the dial, an interval sufficiently long to
cause the release of relays 904 and 905. However,
due to the operation of relay 9!“ prior to the re
lease of relays 905 and 904, relay 502 is released,
whereupon the short circuit to the battery side of 65
the winding of relay 903 is removed and this relay
now operates in parallel with relay 909 in a cir
cuit which extends from ground and battery
through resistance 924, winding of relay 908, front
contacts of relay 009, to ground on conductor 923.
When relay 908 operates and, as soon thereafter
as relay 905 releases, a circuit is completed for
relay 906 which extends from ground and bat
tery through the left winding of relay 9%, left
front contacts of relay 908 to ground on the right 76
7
2,136,620
outer back contacts of relay 905. Relay 906 o-p-.
crates and locks over'its right winding and right
inner contacts. to ground on conductor 923.
Now,
due to the operation of relay 905 and the prior
release of relay 905, relay 503 does not release be
cause of a holding circuit which extends from bat
tery through its winding and top inner contacts,
conductor 520, left outer contacts of relay 995,
left inner contacts of relay 996, conductor 925,
10' bottom outer contacts of each of the relays 5H3,
BIZ and 5| I, to ground.
A circuitis now com
pleted ‘for relay 5I2 which extends from ground
von the left back contacts of relay 996, right middle
contacts of relay 906, right outer back contacts
15 of relay 90'I, conductor 92%, bottom middle con»
tacts of relay 503, top winding of relay 5B2, to
battery and ground.‘ Relay 5I2 operates over its
top winding and locks over‘its lower winding and
bottom inner contacts to ground on conductor 923.
20 The operation of relay 5I2 registers the tens digit
3 and unlocks relay 593 which releases.
The subscriber now dials the second or units
digit which, under our assumption is the digit 1.
When relay I 0 I it releases on the line interruption,
relays 904 and 905 operate as before described
and the previously traced pulsing ground causes
the operation of relay ‘903, after which a pre
viously described circuit path is completed for
operating relay 50I which further looks over con
80 ductor 9“! to ground on the right middle con
tacts of relay 90L When relay 995 operates at
the beginning of the pulse a shunting circuit is
completed for relay 909~which extends from
ground on the right outer front contacts of relay
905, left outer contacts of relay 99%, right front
contacts of relay 909, to resistance 922. Relay
909 releases but relay 903 continues to hold
through the right normal contacts of relay 909 to
ground, as traced, on the right outer front con“
tacts of relay 995. ‘On the reoperation of relay
IOI3, at the termination of the pulse, relay 99i
operates in series with relay 903 followed ‘by the
operation of relay 909 and, after an interval, re
lays 905 and. 994 release, causing the release of
46 relays Bill and 903 after which relay 5!“ re»
leases. Further, with the release of relay 995, the
holding circuit for relay- 909 is broken and this >
relay releases. Thereupon, a circuit is completed
for relay 901 which extends from ground and bat
50 tery through the winding of said relay, right out
relay 506, conductor 52I, No. I contact-set of ‘re
lay 9I0, right outer front contacts. of relay 991,
right middle contacts of relay 900 to ground on
the left back contacts of relay 994. Another cir
cuit is also completed for relay 5i 5 which extends
from ground and battery through the lower wind
ing of relay 5I5, No. 0 contact-set of. relay 5%
to ground as traced on conductor 52%. Both of
these relays operate and then look over their re
spective top windings. and top inner contacts to 10
ground on conductor 923.
The reason why, in the case of any units digit
higher than 1, it is necessary to operate one or
more of the four relays 5I4-5I'I is the fact that,
for each digit including 1, a record of the digit 15
must be preserved for the future operation of the
proper selecting magnet in the link for reaching
the wanted line. Each of the ?rst two digits of
the Wanted number represents a speci?c func
tion which must be performed to reach the 20
wanted line. Referring to Fig. 12, it is evident
that the ?rst, or tens digit, represents the particu
lar link frame on which the wanted line termi
nates. Since the invention‘ can accommodate a
maximum of ?fty lines with ten lines to the frame, 25
it is obvious that the lines on the ?rst frame will
have a tens digit which will identify the frame,
and inasmuch as the digit 1 is not used as the
tens digit, all the lines located on the ?rst frame
will have a digit 2 for the tens digit while those 30
on the second frame will have a digit 3. I have
chosen to illustrate my invention as adapted to
twenty lines, spread over two frames with an
additional “split” frame to accommodate two
more links that could not be accommodated on 55
the ?rst two frames, so that the lines terminating
on the ?rst frame all have a 2 as a tens digit
and those terminating on the second frame have
a 3 as a tens digit. In other groups of ten lines
each were to be added to the of?ce up to a maxi— 40
mum of ?fty lines, then each of these groups
would have a 4, a 5 and a 6, respectively, as the
tens digit.
.
'
Hence, so far as the operation of the invention
is concerned, the tens digit is used to identify the 45
frame on which the wanted line is located, and
this fact is recorded on the operation of one or
more of the three relays 5“ to 5I3, inclusive, by
the connection of ground to‘ one of the ?ve con
ductors that identify each of the frames accom
er contacts of relay 909, left back contacts of re» modating a group of ten lines. Since the illus
lay 908, right outer back contacts of‘ relay 935 to ' tration of the operation of the invention has been
ground. Relay 9-01 operates and locks to ground limited to twenty lines, ten on each frame, only
two of these conductors, namely 522 and 523,
on conductor 923.
'
are used and connected to such parts of the cir
Now if the units digit of the wanted subscrib
er’s number had been any other digit than the cuit as are controlled over these conductors; the
digit 1, say the digit 6, then six pulses would have remaining three being bracketed and labeled “to
been dialed and would have resulted in the opera— other frames as required.” Since, in the call
tion of relay 506 by circuit operations similar to being illustrated, the wanted subscriber is located
60 those described for the hundreds digit 3. When, on the second frame and therefore involves the
digit 3 as the ?rst digit, the relay operated on the
in
crates
this on
assumed
the second
series pulse,
of six ground
pulses, relay
is connected
5512
tens digit 3 was relay 5I2 to make conductor
to resistance 922 over a path extending from the 523 effective at the proper time.
The relationship between the operation of the
right outer front contacts of relay 905, conduc
relays 5| I--5I2 and each of the tens digit which
tor 92!, top outer contacts of relay 592, conduc
may be used in an exchange having ?fty lines,‘
tor 5l9, right front contacts. of relay 908 to re
sistance 922. This causes relay 999 to be shunted ten lines to the frame is as follows:
50
55
60
65
and released, causing relay 908 to be held locally
so long as relay 905 remains operated; that is,
until all the six pulses of the digit are received,
at which time it releases and completes the op
erating circuit of relay 901, already described.
A circuit is now completed for relay 5M which
‘extends from ground and battery through the
753 lower winding of relay 5M, No. 3 contact-set of
Digit
Relays operated
70
8
2,136,620
The seconds or units digit of the subscriber’s
line is that which identi?es the horizontal level
in the frame on which the line terminates, and
this fact is recorded in the four register relays
5I4 to 5H, inclusive, in order to eventually pre
pare a circuit for operating the horizontal magnet
involved for reaching the wanted line. These
relays are operated or non-operated in particu
lar combinations by the operated relay in the
10 group of relays 50I to 5I0 which is responsive to
the digit dialed. In the case of the call being used
to illustrate the operation of the invention and
which has the digit 1 as its units digit, none of
these relays was operated following the operation
15 of relay 50I. If the wanted line had had the
digit 6, as assumed for detailing the function of
relays 5“ to 5I'I, then relays 5M and 5I5 would
have been operated as described.
The relation
ship between the units digit dialed and the
20 relays operated is as follows:
Digit
Relays operated
be held over its No. 8 contact-set to ground on
conductor 923 in preparation for making the busy
test of the wanted line as explained hereinafter.
The operation of relay 9I0 further causes a cir
cuit to be completed which extends from ground
on the left outer back contacts of relay 9| I, No 2
contacts of relay 9I0, conductor 928, right wind
ing of relay I00'I1, conductor I028, left contacts of
relay I03, right back contacts of relay I02, bat
tery and ground. Relay I00‘!1 operates and com 10
pletes a locking path extending from ground on
conductor 928, left winding of relay I00'I1 and
left inner front contacts, conductor I029, Wind
ing of relay I03, right back contacts of relay I02,
to battery and ground. Relay I03 operates in this 15
locking circuit, opens the operating circuit of re
lay I00‘!1 at the left contacts of relay I03 and also
the operating circuit of relay I001 in every link.
The locking circuit of each of said relays is like
wise opened by the operation of relay I00'I1 since
said locking circuit is controlled over conductor
I030 which extends over the back contacts of each
of relays I001 in a chain arrangement, so that
once relay I001 of one link is locked, correspond
ing relays in other links cannot operate, thereby
looking out other links which may be seeking
access to the frame containing the wanted line.
Relay I00'I1, on operating, closes an obvious
circuit for relay I006 which, on operating, causes
a circuit to be completed for relay 9II extending
Returning, now, to the number being dialed by
station 624; that is number 3I9, and remembering
that the dialing of the units digit 1 resulted in
the non-operation of the relays 5M to 5“, as well
as the release of relays 908 and 909 and also the
release of relay 50I, the subscriber is now ready
to dial the last or the ringing digit 9. Each of
the pulses of the digit causes the operation of re
40 lays 900, MI, 902 and 903 in the manner de
scribed, followed by the successive operation and
release of relays 50I-509. It will be recalled,
however, that during the dialing of the units digit
and as a result of the operation of relay 905 at the
beginning of the digit and its release at the end
of the digit, relays 908 and 909 were released.
However, when the second pulse has been received
and relay 502 has operated in consequence, a
previously described circuit path is closed for re
lay 909, causing said relay to operate. When
relay 502 releases, relay 908 is operated in para
llel with relay 909, as before described. On the
ninth or last pulse, relay 509 is operated and held
over its locking contacts to ground on conductor
520 so long as the pulsing relay 903 remains op
erated. However, at termination of the pulse, the
release of relay 905 causes a circuit to be closed
extending from ground through the right outer
back contacts of relay 905, left front contacts of
relay 908, left outer contacts of relay 901, left
winding of relay 9I0 to battery and ground. Re
lay 9I0 operates, locks over its right winding and
No. 4 front contacts, conductor I026, bottom outer
contacts of relay I002 to ground on the No. 4 con
tact-set of relay I0I51,, and extends ground over
its No. 5 contacts to the right winding of relay
90I, causing the pulsing relays 900, 90I, 902 and
903 to hold after the release of relay 904 follow
70 ing the termination of the last pulse of the ring
ing digit. With relays 903 and 900 remaining op
erated, relay 509, instead of releasing as it would
have done if it had operated on a 9 units digit,
remains locked to ground on the N0. 5 contacts of
relay 9I0. Relay 9I0 further causes relay 904 to
from ground through the right outer contacts of
relay I906, conductor I03I, winding of relay 9| I,
to battery and ground. Relay 9“ operates and
looks over its right inner front contacts to ground
on conductor I020. In the meanwhile, the oper
ation of relay I0011 causes the connection of
ground to conductor I032 which extends to the
top armature of relay 5“. Inasmuch as relay
5I2 has been operated for the tens digit 3, said
ground is extended to complete a circuit over the 40
top back contact of relay 5II, top outer front
contacts of relay 5l2, top inner back contacts of
relay 5I3, conductor 523, winding of relay 605 to
battery and ground; winding of relay 604 to bat
tery and ground and winding of relay 603 to bat 45
tery and ground. Relay 603 operates and opens
the path of each horizontal selecting magnet on
the second frame, each of which extends back to
a corresponding line relay of a subscriber’s line on
this frame; relay 604 operates and extends the 50
operating winding of each of said magnets to
each of the ten conductors extending to the con
tacts of relays 5I4-5I1, while relay 505, over its
left front contacts, connects ground and battery
to each of the operating windings of said hori 55
zontal magnets while over its right inner con
tacts it extends ground to conductor 62I which is
connected to the operating windings of all link
holding magnets 10 I 1-1017.
Since the units digit of the wanted subscrib 60
er’s number is 1, and since the impulse of this
digit resulted in the operation and locking of
none of the relays in the group of relays 5I4-5Il
inclusive, a circuit is completed which extends
from ground on the right inner contacts of re 65
lay I00'I1, conductor I033, left outer contacts of
relay 500, bottom outer back contacts of relays
5I4-5I‘I inclusive, conductor 524, No. I contacts
of relay 604, right winding of horizontal select
ing magnet 601, left contacts of relay 605, to bat 70,
tery and ground. Magnet 60‘! operates and pre
pares the horizontal cross-points for contact with
the vertical at the link attached to the cross
point of the calling line. In the meanwhile, the
ground connected to conductor 62I completes a II
9
2,136,620.
circuit through the top winding of. holding- mage
netllllllof the ?rst link, conductor. 102,, left con
tacts of relay I006 to battery and ground.‘v Hold:
ing magnet 'I0I1 operates over its top winding and
then looks over its lower winding and contacts in
a previously‘ described circuit. . Since the circuit
of horizontal selectingnmagnet 601. was ‘closed
ahead of that, of holding magnet 'I0I1 by the fact
that the former circuit is completed, by relay
10 10011 and that of the latter by relay lime which
is slow-operate, the crossepoint contacts, con
trolled by ‘magnet 601 are set‘ for lockingunder
control of magnet 'I0I1 in advance of the opera,
means» noti?ed that the called line is busy and
restores‘ his receiver to the switchhook.
If the, wanted line is not busy, relay GM is
normal, relay I009 does not operate and the cir
cuit of relay I005 is completed as before de
scribed. Relay I005 operates and looks over its
operating path to ground on conductor .929. It
further completes a circuit for operating the
called line cut-off relay 6I3 which extends from
ground through the bottom middle contacts ‘of . 10
relay I005, conductor I039, fourth contact of
cross-point ‘J03, conductor 025, right outer back
contacts of relay 6I4, winding of cut-off relay
tion of said magnet, as required for the proper
M3 to battery and ground. Relay 6I3 operates,
operation of across-bar switch.‘ -
removes the ‘line relay 6I2 from the line and pre 15
vents the subscriber from initiating a call.
As soon as relay I005 is operated, the wanted
line is out throughtto the calling line prepara
tory to the closure of the ringing circuit over a
path hereinafter described.
20
‘It will be recalled that, when the link is seized,
the alarm circuit shown in Fig. 11 begins to func
a
When relay 9H operatesit opens the circuit
of relay I00'I1 which, on releasing, further re
leases relay I000 disconnects ground from con
ductor 023 which latter causes the release, of all
20 relays locked to said conductor including relay
904, connects ground to conductor IOI8 which
extends to the winding of relay [M3 to replace
ground supplied from conductor 9I5, andif the‘
wanted line is idle after testing it in, the manner
25 to be described hereinafterhcompletesa circuit
tion as soon as ground is connected to conductor
I023, and that the pairs of counting relays like
relay I I I5 and IIIO operate and release to count 25
which extends from ground through the i left
off time in the manner described.
inner back contacts of re1ay‘500, conductor 525,
relay III'I operates, ground is connected to con
ductor H39 through the left middle back con
tacts of relay I I I9, right middle back contacts of
left middle contacts of relay 9| I_, right outer cone '
tacts of relay 904, conductor 929, right outer
'30 contacts of relay I009, winding of relay I005, to
battery and ground.
.
»
l
,
‘
V
'
.If the wanted line'is busy, relay 6I4 of said
line is operated and as ‘soon as cross-point, ‘I03 is
operated and before relay 9| I shall have had time
35; to operate and, therefore, remove ground from
conductor 923,,a path is completedfor relay I000v
which extends from ground. and battery through
the winding of saidvrelay, conductor I045, right
inner contacts ‘of relay 904, conductor I039, third
40 contact of cross-point ‘I03, conductor 625, right
outer front contacts of relay 6 I4 to ground. Re
lay I009 operates, locks to ground onthe No. 3
contact-set of relay IllI5l under the control of
As soon as
relay III8, right inner front contacts of relay
III'I, to conductor H39 which further extends
through the‘right middle back contacts of relay
I009, top inner continuity contacts of relay I004,
conductor I036, left inner contacts of relay 9| I,
conductor 930, conductor I031, winding of relay
I004 to battery and ground. Relay I004 operates
and looks over its top inner front contacts, con
ductor I038, to ground through the left outer
back contacts of relay III2 which is normal at
this time.
_
During the period in which relay I004 is oper
ated, the called subscriber’s station is being rung,
40
and this period is measured from the ?rst re
lease of relay H02 to the operation of relay IlI2
on the eighth consecutive release of relay H02, 45
the bottom inner back contacts of relay IO0I,
45 cuts off the operating circuit of relay I005, opens
the circuit of relay I I00 which, however, does not
release at this time because it is held up over
as already described.
another ground to its right winding extending
over conductor II43, bottom inner contacts of
relay i005, No. 1 front contacts of relay I009, to
50
ground through the No. ?lcontacts ‘of‘relay,
I0I51, and completes a busy tone circuit for the
calling line which extends from ground through
the right winding of inductioncoil I:I3I, left
55 inner front contacts of relay. III5, condenser
H44, conductorv H46, No. 6 contacts of relay
I009, top outer back contacts of relay I005, top
ing circuit to the called subscriber’s line and in
theproper ringing code combination determined
by the last digit of the wanted number which, in 50
this case, is determined by the digit 9 and, there
fore, by the operation of relay 509. Inasmuch as
the operation of the invention is being disclosed
with respect to a rural exchange having ?ve sta
tions ‘on the tip conductor of the line and ?ve 55
stations on the ring conductor, the different sta
tions must be rung by a code individual to each
station although the invention is not limited to
outer back contacts of re1ay‘l004, upper winding
The operation {of relay I 004 completes the ring
of relay I002, to ground and,-in parallel there
a‘, plurality of stations on one line or even to a
with through condenser I044, bottom outer cone
single station. Under these circumstances, re 60
lays I I23 to H26 each provide a different ringing
tacts of relay IO0I, bottom outer back contacts
of relay I000, conductor IOI'I‘, second contactfof,
cross-point, 3I4, conductor‘ BI I, subscriber’s loop
624, conductor 609, ?rst contact of cross-point
3I4, conductor 3I6, top outerback contacts of
relay I000, top outer contacts of relay IO0I, con-‘
denser I034, lower winding of relay I002 to bat
tery and ground and, in parallel therewith, bot
tom back contacts of relay I004, bottom outer
70 back contacts of relay I005, No. 5 contacts of
code for each of the ?ve stations on one of the
line conductors and the circuit for operating each
of 1 said ‘relays is controlled in the appropriate
order and for the required length of time by the 65
pairs of counting relays shown in Fig. 11. Inas
much as this part of the circuit is ancillary to
the operation of the invention in that ringing
code relays and the manner of their control are
scriber hears the‘tone which ‘isinterrupted at
regular intervals by the operationand release
well established in the art, it is not deemed 70
necessary to describe the various operating cir~
cuits for the relays H23 to H26 except to men
tion the fact that relay II22 provides a code of
two medium rings per cycle; relay H23 three
of . relay? I I I5 ‘asbeforedescribed.
short rings; relay H24 four short rings; relay 75
relay I009,‘conductor H41, condenser H45, right‘
inner contacts of relay I I I5 to ground. , The sub
He is by this
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