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Патент USA US2124846

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Julyze, 193s.
D. F. DE LONG
2,124,846 l
CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS
Filed Sept. ll, 1935
BUS.
CoOnT‘rñolce
FLA.IG.
6 Sheets-Sheet 2
July 26, 1938.
D. F. DE LONG
2,124,846
CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS
Filed sept. 11, 1935
6 Sheets-Sheet 3 .
E
July 26, 1938.
D. F. DE LQNG'
l 2,124,846
CENTRALIZED TRAFFIC CONTROLLING -SYSTEM FOR RAILROADS ’
'Fired sept. 11, 1935
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D,` F, DE LONG
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CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS
Filed Sept. ll, 1955
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July_26, 1938.
D. F. DE LONG
2,124,846
CENTRALIZED TRAFFIC CONTROLLINGv SYSTEM FOR RAILROADS
Fivled Sep'fw, l1, 1935
6 Sheets-Sheet 6
.:oP_antîeau@
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ATTORNEY
Patented July 26, 1938
UNITED STATES PATENT OFFICE
2,124,846 .
CENTRALIZED TRAFFIO CONTROLLING SYS
TEM FOR RAILROADS
Darrol F. De Long, Rochester, N. Y., assignor to
General Railway Signal Company, Rochester,
N. Y.
Application September 11, 1935, Serial No. 40,114
9 Claims. (Cl. 177-353)
This invention relates to centralized traffic con
trolling systems for railroads, and it more par
ticularly pertains to the communication part of
such systems.
5
By means of the centralized traflic controlling
system contemplated by the present invention,
a central control ofñce is placed in communication
with a number of outlying field stations in such
a way that controls may be transmitted to these
10 field stations for governing the operation of
traino controlling devices located at the various
stations. Likewise, the conditions of the various
trañic controlling devices at each station are
transmitted from each station to the control ofi-ice
to advise the operator of the location of trains
and the condition of the traffic controlling de
vices, such conditions being transmitted as indi
cations.
The present invention more particularly relates
to a centralized tra?ilc controlling system wherein
the supervision of the traiiic governing devices
and the indication of their conditions are accom
L.)
plished over a communication system comprising
two line circuits, namely, a control line circuit
and an indication line circuit. The present in
vention is more particularly directed to a trafñc
controlling system in which a repeater station is
provided when the distance between cer-tain of
the ñeld stations and the control office is `such
Si) that it is impractical to transmit impulses between
i; f)
main line or at some location between the oñice
and the end of the line. It will also be obvious
that laterals may be branched oiî the above
mentioned laterals by means of the repeater ar
rangement disclosed, all within the scope of the
present invention.
Another object of the present invention is the
provision of a repeating circuit so arranged that
the system will operate at its desired speed with
out the need of increasing the size of the line
conductors or providing line voltages beyond a
reasonable value. As a result of the repeating arf
rangement provided in the present invention, in
stallation costs of a centralized trailic controlling
system are reduced because it is possibleV to keep ‘
the size of the line battery and the line conduc
tors down to a minimum. In other words the
present circuit arrangement is so arranged that
when the economical limit of line wire size is
reached and the economical limit of battery size 20
is reached, the line circuit will be arranged to
repeat into another line circuit for the trans
mission of controls and indications, with this
process repeated asvoften as required.
Another object of the present invention is the
provision of a circuit arrangement >for directly
repeating impulses from a primary control line
circuit in straight time cascade into asecondary
control line circuitf
Y YAnother object of the „present invention is the so
the control oflice and these certain field stations
without the use of undesirably high line voltages
.provision of a storage> arrangement in _the _re
and/or unduly large line conductors, because
from a distant ñeld station during a _particular
cycle of `operations leave the field stations on one
half-step of the stepping mechanism and 4arrive
of the length of the line circuits.
An important feature of the present invention
is a storage and repeater arrangement, whereby
it is possible to store indications from a distant
station in the repeater station during one half
step of the stepping mechanisms and repeat the
stored indications from the repeater station to
the oñice during the next half-step. of the stepping
mechanisms.
In accordance with another feature of the
present invention it is possible to operate one or
more laterals or branches extending from the
main line of the communication system without
the necessity of looping the line circuits of such
laterals in series with the main lline circuit, with
the consequent need of high voltage and/or large
line conductors. It will be obvious from the
Ydescription which follows that the .repeater sta
tion as disclosed in the present invention may be
installed at the locations where such laterals
.branch off from the main line, irrespective of
Cn Ul whether this branch is made at the end of the
peater station whereby indications transmitted
at the control oñice on the >following ¿half-step
when only Yone repeater station >*is employed.
When two repeater stations are employed, indi
cations transmitted from a ñeld station beyond
the second repeater station leave such field sta 40
tion on one half-step of the stepping mechanism
and arrive at the control office on the second
half-step following. This arrangement of storage
and repeater station is so organized that irrespec
tive _of the number of` repeater stations employed,
the length of the operating cycle for anygiven
capacity remains the same, or in other words,
the'number of steps necessary for the stepping
mechanisms for the control oñice and Athe Iield
stations between the control office and the ñrst 50
repeater station remain the same irrespective of
Athe use of one or more repeater stations.
Other objectsVpurposes and characteristic fea
tures of the present invention will bein partpob
vious >`from the accompanying drawings and in 55
2,124,846
2
part pointed out as the description of the in
vention progresses.
The system of the present invention is an im
provement over the repeater system disclosed in
the prior application of W. D. Halles, Ser. No.
33,826, ñled July 30, 1935, Patent No. 2,097,789
dated November 2, 1937.
In describing the invention in detail reference
will be made to the accompanying drawings, in
10 which like reference characters designate corre
ation of the system especially since the operating
and stick circuits of the FC relay are not shown
in the present disclosure.
Control oûïce equipment-The control orñce
equipment includes a neutral line relay F which
repeats the impulses applied to the control line
circuit, comprising control line conductor CL and
control return conductor CR, from battery CB'.
Neutral line repeating relays FP and ZFP repeat
the impulses applied to relay F and since these
sponding parts, in which distinctive exponents
are used at different locations and in which:
Fig. 1 is a diagrammatic illustration of the lay
out of a system to which the present invention
is particularly applicable.
Figs. lA and 1B illustrate in a diagrammatic
and conventional manner the circuit arrangement
at the control ofiice end of the communication
system.
Fig. 2 illustrates in a diagrammatic and con
ventional manner the circuit arrangement at a
iield station located between the control office
20
and the repeater station.
Fig. 3 illustrates in a diagrammatic and con
ventional manner the circuit organization at the
repeater station.
Fig. 4 illustrates in a diagrammatic and con
ventional manner the circuit arrangement of a
30
ñeld station located beyond the repeater station.
Fig. 5 is a typical indication code table which
will be used in explaining the operation of the
present system.
f
In following the circuits of the present inven
tion Figs. 1A, 1B, 2, 3 and 4 should be placed to
gether in the order named with correspondingly
identified lines in alignment.
For the purpose of simplifying the illustrations
and facilitating in the explanation, the various
parts and circuits constituting the embodiment of
40 the invention have been shown diagrammatically
and certain conventional illustrations have been
employed, the drawings having been made more
with the purpose of making it easier to under
stand the processes and mode of operation than
45
with the idea of illustrating the speciñc construc
tion and arrangement of parts that would be em
ployed in practice. Thus the various relays and
their contacts are illustrated in a conventional
manner and symbols are used to indicate con
nections to the terminals of batteries or other
sources of electric current instead of showing all
of the wiring connections to these terminals.
The symbols (-1-) and (_) are employed to in
dicate the positive and negative terminals re
55 spectively of suitable batteries or other sources oi.'
current and the circuits with which these sym
bols are used always have current iiowing in the
same direction, that is from (-1-) to (_). The
symbols (B+) and (B~) are employed to indi
60 cate the positive and negative terminals respec
tively of a battery or other source of direct cur
rent having a mid-tap (CN) and the circuits with
.which these symbols are used may have current
ilowing in one direction or another depending
upon whether the circuit is connected to (B+)
or (B-).
In the lower right hand portion of Fig. 1B re
lay FC is blocked in, in dotted lines. This is the
same FC relay which is illustrated in the upper
portion of Fig. 1A and in order to simplify the
circuit connections from contact 9| of relay 2SA
`through contact 99 of relay FC to contact 92 of re
lay ZFP, the location of relay FC has been indi
cated in two places. It is believed however that
this will not be confusing in following the oper
relays are of the quick acting type they follow
the operations of relay F with minimum delay.
Slow acting line repeating relays SA and 2SA are
for the purpose of defining the bounds of each
operating cycle, that is these relays are picked up
at the beginning of each cycle, remain up
throughout the impulsing of the cycle and are
dropped at the end of the cycle.
Cycle determining relay C and code determin
ing relay CD are picked up in response to thev
actuation of button SB at the beginning of a.l
cycle, during which controls are transmitted.
The detailed circuits for controlling the operation
of relays C and CD are not shown since they are
immaterial for an understanding of the present 253
'invention and may be arranged as shown in de
tail in the prior patent to T. J. Judge and C. S.
Bushnell Patent No. 2,082,544 dated June 1, 1937.
Field cycle determining relay FC remains down
during a control cycle but is picked up during a
duplex cycle or a cycle for the transmission of
indications alone. The circuit arrangement of
relay FC is likewise omitted from the present
drawings for the sake of simplicity, but this relay
may be controlled in the same manner as dis
35
closed in the above mentioned application Ser.
No. 640,062.
Code sending relays PC and NC are for the pur
pose of applying (-1-) and (_) impulses respec
tively to the control line circuit during a cycle of
operations. Relays MB and MF are for the purpose of receiving indications during an operating
cycle over the primary indication line circuit,
comprising indication line conductor IL and in
dication return conductor IR.
A suitable step-by-step relay bank is employed
including relays VP, IV, 2V and LV. Relay IV,
2V and LV pick up during the de-energized> or
“off” periods of theimpulses in the control line
circuit and relay VP shifts its position during the »
energized or “on” periods of the impulses in the
control line circuit. When the stepping relays
are picked up they are stuck up until the end of
the cycle. Half step relay VP is picked up and
dropped during alternate “on” periods of the
cycle, all of which will be pointed out in detail.
Control line impulsing relay E controls the appli
cation of the impulses to the primary control
line circuit by opening and closing the energizing
circuit of the PC and NC relays at the proper
times as determined by the response of the step
ping relay bank in the control office to the im
pulses applied to the line.
Resistance CRS is a charging resistance for
`precliarging the indication line circuit extending
`from the oflice to the repeater station, to apply a
charging current at the beginning of each inter
val devoted to the transmission of indications.
Although not shown in the present drawings,
it will be understood that the control oilice is
provided with a suitable control machine which
includes a miniature track diagram representative
of the actual track layout in the ñeld. Certain
control levers and buttons which are manually
operable to obtain the desired control are in
3
2,124,846
cluded in the control machine, switch machine
lever >SML and starting button SB being typical
of such devices. It Willbe understood that- a
starting button is provided for each group of con
trol levers and is associated with a particular field
station, so that the positioning of the control
levers for a particular station results in the trans
mission of controls to that station following the
operation of the associated starting button. Sta
tion selection is provided by the particular CD
relay which is picked up in response to the oper
ation of a particular starting button, by connect
ing the PC and NC relays to the channel circuits
selected by the stepping relay bank by means of
code jumpers connected in various combinations
for providing station selecting codes.
For the purpose of illustrating how the recep
tion of indications on the MB and MF relays in
the control office store these indications for the
20 purpose of station registration and indicating
registration, pilot relays IPB, IPF and ZPB are
shown in Fig. lA. Station relays IST and 5ST
are illustrated as being typical of the registration
of a transmitting iield station in the control
25 office by the'selection and operation of one of
these station relays during a cycle of operations.
Indication storing relay IRF is illustrated to
show how an indication received from station
No. 5 is transferred from the message receiving
30 relay MIF during a cycle of operations when sta
tion No. 5 is‘selected. Relay IRF is of the polar
magnetic stick type, that is its contacts are oper
ated to the right and left when (B-) and (B-|-)
respectively are connected to its winding by way
35 of contact 96 of relay MF. It will be understood
that there are other indication storing relays
for receiving other indications from station No.
5 and from other stations in the system, but itis
believed that the illustration of relay IRF and
an explanation of its operation will be suñicient
for an understanding ofthe present invention.
Repeater station equipment-It is assumed
(see Fig. 1) that the present system comprises a
control ofiice connected to a repeater station by
means of primary control and indication line
circuits and that there are four field stations con
nected to these line circuits between the control
oiiice and the repeater station. It is also as
sumed that there are four field stations con
nected to the secondary control and indication
line circuits which extend beyond the repeater
station.
,
The repeater station (illustrated in Fig. 3) in
cludes a biased to neutral polar line relay F3 and a
neutral quick
relays repeat
mary control
The (-1-) and
-the repeating of indications, these relays repeat
ing the operations of line relay FN3 as will be
described in detail. Lock-out relay LO3 func
tions to provide a lock-out operation so that field
stations located in the primary section of the
communication system may obtain access to the
primary line circuits for the purpose of trans
mitting their indications in preference to the
repeater station. 'I'he detailed lock-out feature
will be described later.
10
Resistance CRS3 corresponds to resistance
CRS in the control oñice andis for a similar pur
pose, that is the. secondary indication line cir
cuit is precharged over a circuit including this
resistor to apply a charging current at the be
ginning of each interval devoted to the transmis
sion of indications. Indication battery IB(1 cor
responds to indication battery IB in the control
oiiice and it will be understood that these bat
teries are for the purpose of energizing the sec
tion and indication codes transmitted from a
iield station in the secondary section during one
half step of an operating cycle and transmit the "
corresponding codes to the control oñ‘ice during
a following half-step of an operating cycle.
Resistance I R3 is a compensating resistance for
compensating for the lower winding of relay
LO=3 which is removed from the primary indica
tion line circuit after the lock-out period of a
cycle. Resistance 2R3 is a compensating resist
ance to compensate for the value of resistance
of the primary indication line circuit which is
disconnected when the repeater station is trans
mitting. It will be understood that when the
repeater station is located at the end of the pri
mary section, as illustrated in Fig, 1, resistance
2R3 is not required and the terminals to which
it is connected are strapped by a jumper and the i
resistance removed. On the other hand, if the
repeater station is located at a point in the pri
mary section With field stations connected farther
out from the control office, then resistance 2R3
is provided, the value of which is determined by
the resistance of the indication line circuit which
is disconnected when the repeater station is
transmitting.
Field station equipment-A field station (see
acting line relay IFS. These line
the impulses applied to the pri
line circuit in the control ofñce.
(_) impulses applied to the pri
ment of Fig. 2 is the same as the circuit arrange
mary control line circuit and received by relay
F3 effect the operation of relays FC3 and NC3
are provided in accordance with the figure num
Fig. 2) located in the primary section is similar .
to a field station (see Fig. 4) located in the sec
ondary section.
Therefore the circuit arrange
ment of Fig. 4 except that reference characters
respectively to apply corresponding polar im
ber and adiil’erent connection of the station iden
pulses to the secondary control line circuit, com
prising control line conductor CL1 and control
return conductor CR1 extending to the ñeld sta
tions beyond the repeater station. The impulses
in the primary control line circuit and the im
tifying code jumpers is-provided at each station.
pulses repeated into the secondary control line
20
ondary and primary indication line circuits re
spectively for the transmission of indications.
Relays MB3 and MP3 correspond to relays MB
and MIF in the control oiiice- and are for the=purpose of receiving indications transmitted from a
field station in the secondary section. These
indication receiving relays receive the registra
These field stations each include a biased-to-neu
tral polar line relay F and line repeating relays
FP, SA and SB (with distinctive exponents),
which relays operate in a similar manner to cor
Slow acting relays S3, SA3 and SB3 are for the
purpose of marking the bounds of cycles of oper
ation, the detailed operation of these relays being
responding `relays in the control oiiice, except
that the line relay is a polar relay for receiving
the polar impulses in the control line circuit.
Relay SB (with distinctive exponent) corresponds
to relay 2SA in the control oilice except, as in
dicated in the field- station drawings, this relay
is not of the slow acting type.
explained later.
Relays FP3 and 2FP3 operate during a cycleffor
relaysvIV.. 2V, LV, and the associated half step 75
circuit are repeated (irrespective of their polar
ity) by neutral line relays IF3 and FN3 respec
tively.
Each field stationincludes a bank ofv stepping
2,124,846
4
relay VP, (with distinctive exponents) operating
substantially in synchronism with corresponding
(Il
relays in the control oiñce, in response to im
pulses applied to the control line circuits. The
detailed circuit arrangement for operating the
stepping relay banks and the line repeater re
lays have not been shown since they may be the
saine as for corresponding relays in the control
oflice.
It is thus believed obvious that the line
repeating relays and the stepping relays operate
in response to the operations of relays FP2 and
F124 by means of circuits which are not shown but
merely indicated by dotted line connections 265
and 465.
Relays PB and PF (with distinctive exponents)
are controlled locally in accordance with the local
jumper connections and the positions of local
relay contacts. YThese relays function to condi
tion the indication line circuits in accordance
with indications to be transmitted during the
different periods of a cycle as will be pointed out
in detail.
-
Lock-out relays L02 and L04 are picked up in
response to» a ñeld start condition at the asso
ciated station and they function to close the pri
mary indication line circuit or the secondary in
dication line circuit respectively, for initiating a
cycle of operations for the transmission of indi
cations from the associated station. It will be
30 understood that lock-out relay L02 locks out
more distant ñeld stations in the primary section
and lock-out relay L04 locks out more distant
field stations in the secondary section, so that
these more distant stations are ineffective to
35 obtain access to the communication system dur
ing a cycle of operations for the transmission of
their indications when the illustrated stations
have use of the line circuits.
Resistance units IR2 and IR4 are compensating
40 resistances for compensating for the resistance
of the lower winding of the associated L0 relay
which is removed from the indication line circuit
after the lock-out period. Resistance ~units 2R2
and 2R4 are compensating resistances to compen
45 sate for the value of resistance in the associated
indication line circuit which is disconnected when
a particular ñeld station is transmitting. When
the iield station of Fig. 2 is transmitting, primary
indication line conductor IL is connected to re
50 turn line conductor IR by way of resistance 2R21,
which resistance is of the proper value to com
pensate for the resistance of the primary indi
cation line circuit which would be completed at
the end station of a series of ñeld stations con
55 nected to the primary indication line circuit.
Likewise, when the ñeld station of Fig. 4 is trans
mitting, the secondary indication line conductor
IL1 is connected to return conductor IR1 by Way
of resistance 2R4, which resistance is of the
60 proper value to compensate for the resistance of
the secondary indication line circuit which would
be completed at the end station of a series of
ñeld stations connected to the secondary indi
cation line circuit.
Track switches TS2 and T84 are illustrated as
being controlled by switch machines SM2 and
SM4 in response to the operation of switch ma
chine relays SMR2 and SMRA. VThe occupied
and unoccupied conditions of the illustrated
track sections are repeated by track relays T2
and 'I'4 in the usual manner.
The control of the signals 'at the illustrated
stations has not been shown, since the control of
the switch machine may be considered typical of
75 the manner in which additional steps of the
cycle function to control signals in response to
additional impulses. Change relays CH2 and
CH4 are normally energized and are dropped
(circuits not shown) in response to a change in
condition at the associated ñeld station, for ini
tiating the system into a cycle of operations for
the transmission of indications.
The station selection portion of the system is
not illustrated since this feature is immaterial
for an understanding of the present invention. 10
Station selection may be provided as explained in
detail in above mentionedv Patent No. 2,082,544.
It need only be mentioned here that station re
lays S02 and S04 are picked up at the beginning
of a control or duplex cycle and remain up after
the station selection steps of a cycle at the as~
sociated station only when controls are to be
transmitted to this associated station.
General operation
20
For convenience in describing the operation of
this system the control line circuit and the indi
cation line circuit (see Fig. 1) extending from
the control oñice to the repeater station will be
referred to as the primary control line circuit and
the primary indication line circuit respectively.
The control line circuit and the indication line
circuit extending from the repeater station to
the distant ñeld stations will be referred to as the
secondary control line circuit and the secondary 30
indication line circuit respectively. It will be
understood that the number of field stations in
cluded in the primary and secondary line circuits
may be varied to suit operating conditions but
the arrangement illustrated in Fig. l is typical. 35
The repeater station of the present invention
repeats or retransmits the controls to the sec
ondary section in straight time cascade, while the
indications from the secondary section are trans
mitted to the repeater station on one half-step
of a cycle of operations and then repeated or
retransmitted to the control office on the following
half-step. In other words an indication from
any iield station in the secondary section leaves
the transmitting field station on one half-step
and arrives at the control oiîice on the following
half-step.
From the above it will be obvious that a iield
station in the secondary section cannot register
a pulse in the control ofñce during the i'lrst “off”
period or iirst half-stepof a cycle. It will be
pointed out during the detailed description of the
operation of the.4 system that practical use is
made of this inability to transmit from the sec
ondary section into the control oilice during the
ñrst “off” period, so that no loss of station or
indication capacity will result for those stations
connected to the secondary section, by deliber
ately assigning the station registration codes for
all stations in the secondary section to start 01T 60
with a non-pulse on the iirst half-step.
As noted in Fig. 1, and for convenience in
describing the operation of the system, a -|- digit
of a code is one which impulses or closes the indi
cation line circuit, While a _ digit of a code is a
non-pulse or one which leaves the indication line
circuit open. It will be observed that the ñrst
code digit of all the stations in the secondary
section begin with -.
In accordance with the
above discussion and as will be later pointed out, 70
it will be apparent that this - digit (non-pulse)
eiîects the registration of this digit for stations in
the secondary section during the first “off” period
without the actual transmission of any code digit
75
from the repeater station to the control office.
2,124,846
In the event that any one of the field stations
connected to the secondary line circuit (secondary
section of Fig. 1) has new indicationsto transmit
to the control office, the transmitting ñeld station
transmits these indications to the repeater station
where they are received on the MB3 and MF3
relays during one half-step of the operating cycle
and retransmitted to the control oifice in accord
ance with the condition kof the MB3 and MF3 relays
during a succeeding half-step oi" the cycle.
The 1ock-out feature at the repeater station
functions the same as at an ordinary field station.
The repeater station is inferior to all stations
connected to theprimary line circuit (primary
section of Fig. 1), which are located nearer the
control office, and the repeater` station is superior
to all ñeld stations more distant from the control
ofñce. The lock-out feature at the ñeld stations
is of the geographic lock-out type, that is a ñeld
station in the secondary section nearer the re
peater rstation is superior to more distant field
stations connected to the secondary line circuits
and a ñeld station in the primary section nearer
the control oiîice is superior to vmore distant sta
tions ~in that section.
One or more repeater stations may be used as
required and if more than one repeater station is
used in the system the controls are repeated inthe
same manner as illustrated in the accompanying
drawings Without any storage feature, While the
indications are first received at the repeater sta
tion associated with the line section to which the
transmitting ñeld station is connected during one
half-step of the stepping mechanisms associated
= with this section, with the received indications
retransmitted from the repeater station into the
.next section during a following half-step of the
stepping mechanisms and this is repeated as Ymany
times as there lare repeater stations in the system.
The line circuits of a selector system such as
disclosed in the above mentioned Patent No.
2,682,544 comprise a control line circuit, including
control line conductor CL control return conduc
tor CR, and an indication line circuit including
indication line conductor IL and indication return
conductor IR. VThese two line circuits correspond
to the control line circuit, including conductors l0
and i2, and the indication line circuit including
conductors l 4 and l5 of the above mentioned prior
application. In a system of this character the
control line conductor CL is connected .to the
control return conductor CR at the repeater sta
tion associated with the primary line circuit, with
the line relays of any field station` Orstations
Si :i between the repeater station and the control
cnice, as well as the line relay at the control oiîice
and at the repeater station connected in series
with the primary control line wire.
The primary control Yline circuit is energized
with positive and negative impulses from a control
line battery in the control oñice for the purpose of
transmitting controls and `for the purpose of caus
ing the synchronous step-by-step operation at the
5
extends to all _of the ñeld stations connected to the
primary line circuits and normally includes a back
contact, such as back contact 256 of relay LO2 of
Fig. 2, at any station located between the oi'lice
and the repeater station. In the present embodi
ment the primaryindication line conductor ter
minates _at front Contact_¿ßâß of relay LO3 at the
repeater station.
When a particular ñeld station is transmitting,
the look-out relay at that station vis picked up 10
thereby rendering the open or closed conductive
condition ,or the primary indication line circuit
with which the transmitting station is associated
dependent upon the control of either a relay simi
lar to relay PF2 or FB2 of Fig. 2 in accordance 15
withkwhether the primary control line circuit is
energized or cle-energized. It will be understood
>¿hat the above discussion assumes that the trans
mitting _ñeld station is connected to the line
circuits associated with the primary section.
20
A similar condition exists with regard to the
secondary section, that is the secondary control
line circuit includes line relays at the field stations
of this section, with the secondary control line
conductor CL1 permanently connected to the 25
secondary return lline conductor CB1 at the end
station. The lock-out arrangement and the con
ditioning of the secondary indication line circuit
.by the PB4 and PF4 relays associated with the
secondary indication line circuit is similar to the
operation of corresponding relays associated with
the primary indication line circuit, with the sec
ondary indication line circuitl normally open at
the last station.
Detailed operation
Normal conditions-With the system in its
normal condition as indicated in the accompany
ing drawings, the primary control line circuit and
the secondary control line circuit are both de .40
energized. The primary indication line circuit
and the secondaryindicationline circuit are both
normally open. All relays in the control oflice
and at the lrepeater station are normally de-ener
gized. .All relays at the ñeld stations (Figs. 2 and
4) are likewise normally de-energized, with the
exception `of the track relays T2 and T4 which are
illustrated in their picked up conditions since it is
assumed that the associated track sections are
unoccupied. Change relays CI-I2 and CI-I4 are
normally energized and are likewise shown in 5,0
.their picked up conditions since it is assumed that
no ñeld start has been initiated.
For convenience in describing the operations
which follow, the energized or impulse periods of
the control line circuits will be referred to as
f_‘on” periods, while the de-energized periods be
tween impulses Will be referred to as “off” periods.
The system will be described as stepping through
cycles each comprising a conditioning “on” pe 60
riod, a first “ofi”> period, a first “on” period, a
second.“oiî” period, a second “on” period and a
third (clearing out) “oif’ïperiod vThese ñve dis
control cnice and at the primary stations, as will tin'ctive periods (exclusive of the clearing out pe
be later explained.
riod), of an operating cycle are illustrated in the
The primary indication line circuit is ,energized - code tablepf Fig. 5 and will be referred to later
from an indication line battery in thecontrol in describing the transmission of codes from sta
oilice, having included therein at the control office, tions-in the-primary and secondarysections.
message receiving relays MF and MB which are
lJlfamtal start-It will ñrst be assumed that the
controlled through front and yback contacts re
operator in the control oiiice desires to move 70
spectively of relays FP and 2F13, as well asA through track switch T84 at the field station illustrated in
contacts of relays PC and NC, .to include these Fig.; llirom'its normal locked position to its re
message receiving relays in thel indication line
circuit at the properintervals of the operating
cycle. The primary indication line `conductor
verse locked position. It willbe assumed that
therillustrated ñeld station responds lto a code
combination of (-1-) and (-) Onthe lñrst two 7.5
2,124,846
6
steps of the operating cycle. It will also be as
sumed that the track switch is operated to its
reverse position in response to a (_) impulse on
the third step of the cycle.
With the system in its normal condition the
actuation of starting button SB in the control
ofûce is eiîective to pick up relays C and CD for
initiating a control cycle. Since the detailed cir
cuit arrangement for controlling the C and CD
relays is immaterial for an understanding of the
present invention it has been omitted from the~
present disclosure, but this circuit arrangement
may be the same as disclosed in the above men
tioned application Ser. No. 640,062. It will be
understood that only one CD relay can be picked
up at any one time and only at the time the sys
tem is in its normal condition.
The picking up of relays CD and C closes a
circuit for picking up relay PC which extends
from (-1-), (Figs. 1A and 1B) back contact 38 of
relay E, conductor I0, front contact 4| of relay C
back contacts 43 and 44 of relays 2V and |V re
spectively, conductor 45, front contact 46 of relay
CD, code jumper 5, PC bus 41 and winding of
25 relay PC to (_).
11n/pulsing and stepping operations-_The pick
ing up of relay PC energizes the primary control
line circuit with a (-1-) impulse to mark the be
ginning of the conditioning “on” period. this
30 impulse circuit extends from the (-1-) terminal
of battery CB, front contact 5| of relay PC, back
contact 54 of relay NC, winding of relay F, pri
mary control line conductor CL, winding of relay
F2, primary control line conductor CL, windings
of relays F3 and |F3, primary control return con
ductor CR, back contact 50 of relay NC and front
contact 53 of relay PC to the (_) terminal of
battery CB.
This energization of the primary control line
40 lcircuit picks up relay F in the control oñice and
positions the polar contacts of relay F2 (and sim
ilar line relays at any other stations connected to
the primary control line circuit) to the right.
Relay F3 at the repeater station likewise positions
its polar contact 381 to the right and relay IF3 is
picked up. Relay F closes an obvious circuit at
its front Contact 61 for picking up relay FP, re
lay FP closes an obvious circuit at its front con
tact 68 for picking up relay EFP, relay l2FP closes
50 an obvious circuit at its front contact 69 for pick
ing up relay SA and relay SA closes an obvious
circuit at its front contact 10 for picking up relay
2SA.
Relay F2 closes an obvious circuit at contact
55 261 in its right hand dotted position for picking
up relay FP2. The following impulses which are
applied to the control line circuit effect the inter
mittent operation of relays F2 and FP2 which, by
means of circuits not shown in Fig. 2, control the
60
operations of the relays SA2, SB2, VP2, |V2,
2V2 and LV2, but since these operations are simi
lar to corresponding operations at the ñeld sta
tion of Fig. 4, which will be pointed out later, it
is believed unnecessary to complicate the dis
65 closure by including the detailed circuits of the
above mentioned relays at the primary station
(Fig. 2).
Relay F3 closes an obvious pick-'up circuit for
relay PC3 at contact 361 in its right hand dotted
70 position. Relay PC3 closes an obvious circuit at
its front contact 366 for picking up relay S3 and
Relay S3 closes a circuit for picking up relay SB3,
which extends from (-1-), front contact 310 of
relay S3, back contact 38| of relay LO3 and Wind
ing of relay SB3 to (_).
The picking up of relay PC3 applies a (-1-) im
pulse to the secondary control line circuit over a
‘circuit extending from the (-1-) terminal of bat
tery CB1, front contact 35| of relay P03, back
contact 354 of relay NC3, winding of relay FN3,
secondary control line conductor CL1 (and in
cluding other line relays at any other stations
connected to the secondary control line circuit) ,
Winding of relay F4, secondary control return
'conductor CRl, back contact 350 of relay NC3 and
front contact 353 of relay PC3 to the (_) termi
nal of battery CB1.
Relay FN3 is picked up in response to the en
ergization of the secondary control line circuit
and relay F4 actuates its polar contacts to the i
right. It will be understood that the line relays
at the field stations interposed between the re
peater station and the field station of Fig. 4 op
erate in response to the impulses applied to the
secondary control line circuit, but since it is be
lieved unnecessary to show the circuits of these
stations, only brief mention will be made of
their operation later in the description.
At the ñeld station of Fig. 4 the actuation of
Contact 451 of relay F4 to the right closes an
obvious pick-up circuit for relay FP4. Although
the detailed circuits are not shown in Fig. 4,
in accordance with the operation of the system,
disclosed in the above mentioned application Ser.
N0, 640,062, the conditioning (-1-) impulse ap 30
plied to the secondary control line effects the
pick-up of the station relays at a portion of the
ñeld stations, such as relays S04 of Fig. 4. Thus,
due to the actuation of contact 4|4 of relay F4
to the right it will be assumed that relay SO4
is picked up and remains in its picked up condi
tion in response to the station selecting impulses
applied to the line circuits for selecting the sta
tion illustrated in Fig. 4, so that the first control
impulse following station selection will be eiTec 40
tive at the station illustrated in Fig. 4, due to
closed front contact 4|5 of relay S04.
As above mentioned, the detailed circuits for
controlling relays SA4, S134, VP4, |V4, 2V4 and
LV4 at the field station illustrated in Fig. 4 have 45
been omitted since this control may be effected
in the same manner disclosed in the above men
tioned application Ser. No. 640,062 and indicated
by dotted line 4‘65.
The energization of the primary and secondary 50
control line circuits as above described is effec
tive to provide the conditioning “on” period of
the cycle. During this “on” period, relay VP
in the control oñice is picked up over a circuit eX
tending from (-1-), front contact 1| of relay SA, 55
front contact 12 of relay 2FP, conductor i2, back
contacts 85 and 13 of relays 2V and iV respec
tively and winding of relay VP to (_). Relay
VP closes a ñrst stick circuit for itself extend
ing from (-1-), front contact 1| of relay SA, con 60
ductor | |, front contact 14 of relay VP, back con
tacts 85 and 13 of relays 2V and IV respectively
and winding of relay VP to (_). The picking
up of relay 2SA (which picks up a little later
than relay VP) closes an energizing circuit for
relay E which extends from (-1-), front contact
90 of relay 2SA, conductor |3, back contacts 3|
and 32 of relays 2V and IV respectively, front
contact 33 of relay VP, conductor |4 and winding
70
of relay E to (_).
The picking up of relay E opens the energiz
ing circuit of relay PC at back contact 38, relay
PC drops and opens the primary control line cir
cuit to mark the end of the conditioning “on”
period and the beginning of the ñrst “off” period. 75
2,124,846
This drops relays F, FP yand ZFP in the control
oñice. Relays F3, IF3 and PC3 at the repeater
station are de-energized, the dropping vof relay
P03 de-energizing the secondary control line vcire`
‘Si cuit which is effective to drop relays F4 .and kFP‘1
at the ñeld station. Relay FN3 is likewise dee
energized in response to the de-energization of
the secondary control line circuit, but since this
relay is ineiîective during a control cycle its op
eration will not further be mentioned during the
description of the co-ntrol cycle operation. It
need only be mentioned that relay FN3 responds
to the impulses applied to the secondary control
line circuit.
.
„
The dropping of relay ZFP in the control otlice
closes a circuit for .picking up relay IV which ,ex
tends from (-1-), front co-ntact l5 of relay SA,
back contact 16 of relay 2FP, conductor i5, iront
contact 11 of relay VP, back contact 18 of relay
2V and winding of relay _IV to (_). Relay IV
closes a stick circuit for itself extending from
(-1-), front contact 15 of relay SA, conductor I6,
front contact 19 and Winding ci relay IV to (_).
This stick circuit for relay IV is maintained en
ergized until relay SA-> is dropped at the vend oi
the cycle. It Will be obvious that relays 2V and
LV, when picked up, close similar stick circuits
for themselves at their front contacts 83 and
84 respectively and it will not be necessary to
30
point out the closure of these stick circuits again
during the operation of the system, since they
are likewise maintained energized until the end
of the cycle.
The picking up of relayIV opens the iirst stick
35 circuit of relay VP at back contact 13, but prior
to this a second stick circuit is closed for relay
VP which extends from (-1-), front contact 1I
of relay SA, back Contact 12 of relay EFP, con
ductor I1, front contact 86 and Winding of relay
40 VP to (_).
The picking up of relay IV de-energizes relay
E at back contact 32 and the dropping of relay
E picks up relay NC over a circuit extending from
(-1-), back contact 38 of relay E, conductor H33,
front contact 4! of relay C, back contact 43 of
relay 2V, front contact 44 of relay IV, conductor
55, iront contact 51 of relay CD, code jumper
6, NC bus 48 and winding of relay NC to (_).
The primary control line circuit is now ener
gized with a (_) impulsev to mark the end of
the first “off” period and the beginning of the
ñrst “on” period. This circuit extends from bat
tery CB, through back contacts 5I and 53 of re
lay PC and front contacts 58 and 54 of relay
NC, which contacts reverse the connection of the
battery applied to the primary control line cir
cuit from that previously pointed out.
The (_) energization of the primary control
line circuit effects the picking up of relays F,
FP and ZFP in the control office, positioning of
the polar contacts of relay F3 at the repeater
station to the left, the picking up of relay IF3
and the picking up of relay N03 over an obvious
circuit closed at contact 361 of relay F3 in its left
hand dotted position. With relay N03 picked up
and relay P03 down, the secondary control line
circuit is energized with a (_) impulse over a
circuit Which includes contacts 35i and,353 of
relay PC3 and contacts 356 and 354- of relay NO3
70 in positions reversed from that previously de
scribed.
The .picking up of relay 2FP in the control
oiiice drops relay VP because its iirst stick cir
cuit is open at back Contact 13 of relay IV and
75 its second stick circuit is open at back contact
7
12 of relay 2FP. The droppin-gef relay VP closes
a circuit for picking up relay E which extends
from (-1-), front contact 98 of relay 2SA, con
ductor I3, back contact 3l Yof relay 2V, front con
tact 32 of relay IV, back contact 33 of relay VP,
conductor I4 and Winding of relay E to (_).
The picking up of relay E de-energizes the
above traced circuit for relay NC, which drops
and de-energizes the primary control line circuit
to mark the end of the ñrst “on” period and the l0
beginning of the second “oiî” period. Relays F,
FP and 2FP are dropped and relay 2V is picked
up over a circuit extending from (-1-), front con
tact 15 of relay SA, back contact 16 of relay
2FP, conductor I5, back Contact 11 of relay VP, 15
front contact 82 of relay IV and Winding of re
lay 2V to (_). The picking up of relay 2V de
energizes relay E at open back contact 3I and
the dropping of relay E energizes relay NC, which
in turn energizes the primary control line circuit 20
to mark the end of the second "oiF’ period and
the beginning of the second “on” period.
Relays F, FP, and 2F12V .are pi-cked up in response
to the energization ofthe primary control line
circuit at the beginning of the second “on” pe 25
riod.
Relay VP is picked up over a circuit ex
tending from (-1-), front contact 1I of relay
SA, front contact 12 of relay 2FP, conductor I2,
front contact 85 of relay 2V and Winding of re
lay VP to (_). Relay VP again completes and 30
prepares its stick circuits which are believed to be
obvious and unnecessary to be pointed out again.
The picking up of relay VP energizes relay E over
.a circuit extending from (-1-), front contact 90
of relay 2SA, conductor I3, front contacts 3| and 35
33 of relays 2V and VP respectively, conductor I4
and winding of relay E to (_).
The picking up of relay E de-energizes relay
NC at back contact 38 and relay NC drops to de
energize the primary control line circuit to mark 40
the end of the second “on” period and the begin
ning of the third or clearing out “01T” period.
Relays F, FP and 2FP are dropped .and relay
LV is picked up over a circuit extending from
(-1-), front contact 15 of relay SA, back contact 45
16 of relay ZFP, conductor I5, front contacts 11
and 18 of relays VP and 2V respectively and
winding of relay LV to (_).
, The picking up of relay LV does not change
the circuit condition of relay E and it remains 50
up, the PC and NC relays remain down and the
primary control line circuit remains de-ener
gized so that relay 2FP remains down for a
suiliciently long period to drop relays SA and
2SA for clearing out the circuits. The dropping 55
of relays SA and 2SA de-energize relays E, VP,
IV, 2V and LV by the opening of front contacts
90, 1I and 15. 'I'he dropping of relay SA also
de-energizes relays CD and C by circuits not
shown in the present disclosure.
60
When relay 2V was picked up during the sec
ond “oiï” period as above described, its contact
43 shifted the energizing circuit from conductor
56 to 6I, which extends this circuit through
front contact 62 of relay CD, lever SML in its left 65
hand dotted line position (reverse) and NC bus
48 to the Winding of relay NC. This is eiïective
to apply a,(_) impulse to the control line cir
cuit during the second “on” period. It Will be
understood that lever SML in its full line (nor
mal) position would energize relay PC instead of
relay NC, so that the Vswitch control impulse
would be (-1-) instead of (_).
i
Referring to the ñeld station illustrated in Fig.
4,. it will be .recalled that the (-1-) and (_) im 75
2,124,846
8
pulses applied to the primary control line circuit
are repeated into the secondary control line cir
cuit by the operations of relays PC3 and NC3
respectively at the repeater station. It will be
understood that the conditioning and the ñrst
impulses, which were assumed to be (-1-) and
(_) because of the connections of jumpers 5
and 6 in the control office, were effective to select
the station illustrated in Fig. 4 by maintaining
relay S04 in its energized condition.
After the stationis selected the next impulse
(second “on”), which was (_) applied to the
secondary control line circuit in response to the
(_) impulse applied to the primary control line
circuit (because lever SML was assumed to be in
its reverse position), positions contact 414 of re
lay F4 to the left.
This closes a circuit for ener
gizing relay SMR4 extending from (CN), winding
of relay SMR4, front contact 416 of relay 2V4,
20 front contact 415 of relay S04 and contact 414
of relay F4 in its left hand dotted position to
(B_) . This positions contact 450 of relay SMR4
to its left hand dotted position for controlling
the operation of the switch machine SM4 for ac
25 tuating track switch TS4 to its reverse locked
position.
It will be apparent that a (-1-) impulse received
at the field station of Fig. 4 during the second
“on” period would position contact 4l4 of relay
30 F4 to the right, which would energize relay SMR4
in the opposite direction for positioning Contact
450 to the right for operating the switch machine
and track switch to its normal locked position.
It will be understood that relays F2, FP2, F4
35 and FP4 which follow the impulses in the pri
fmary and secondary control line circuits remain
de-energized at the end of the cycle for dropping
relays SA2, S133, SA4, SB4, the stepping relays at
the associated stations and relays S02 and S04.
40 Likewise relays S3 and SB3 at the repeater sta
tion are dropped during the clearing out period
because contacts 365 and 356 of relays NC3 and
P03 respectively remain in their dropped away
positions for a comparatively long interval of
45 time when the primary control line circuit is de
energized at the end of the cycle.
Indications
It will be pointed out in the description which
50 follows how the system is initiated from the field
station of Fig. 4 which is-located in the secondary
section and how indications Aare transmitted from
this station, received at the repeater station and
retransmitted to the control office. Although
55 the circuits of a primary ñeld station (Fig. 2)
are shown somewhat in detail it is believed un
necessary to describe the initiation of the sys
tem and the transmission of indications from
this station, since this portion of the operation
60 of the system is immaterial to an understanding
of the present invention and furthermore this
operation has been clearly described in the above
mentioned prior application 640,062. Also, it is
believed that the transmission of indications from
65 the Fig. 4 station by the conditioning of the
PB4 and PF4 relays and the reception of these
indications by the MB3 and MF3 relays at the
repeater station are suiiiciently analogous to» the
transmission of indications by the PB2 and P132
70 relays of Fig. 2 and thereception of these indi
cations on the MB and MF relays in -the con
trol oñice. It will be pointed out in the descrip
tion which follows how the indications which
75 are received and stored by the MF3 and MB3
relays at the repeater station are transmitted to
the control oñice.
Automatic start-«Assuming the system to be
in its normal condition when a change in condi
tion occurs at the ñeld station illustrated in Fig.
4, relay CH4 is dropped in response to such a
change in condition. This closes a circuit for
picking up relay L04 which extends from (-1-),
back contact 401 of relay FP4, back contact 438
of relay SB4, back contact 453 of relay SA4, 10
upper winding of relay L04 and back contact 454
of relay CI-I4 to (_). Relay L04 establishes a
substitute cir-cuit to (_) at its front contact 455
which bridges back contact 454 of relay CH4.
The secondary indication line circuit is ener
gized, in response to the picking up of relay L04,
over a circuit extending from the (-1-) terminal of
battery IB1 (Fig. 3), upper winding of relay MF3,
back contact 352 or" relay IF3, back contact 396
of relay SB3, secondary indication line IL1, front 20
contact 456 of relay L04, back contact 412 of re
lay SB4» lower Winding of relay L04, resistance
2R4 and secondary indication line return con
ductor IR1 to the (_) terminal of battery IBl.
Relay M133 is picked up over the above de 25
scribed circuit and a circuit is closed for picking
up relay L03 which extends from (-1-) , back con
tact 310 of relay S3, back contact 388 of relay
IF3, front -contact 381 of relay MF3, back contact
358 of relay SA3 and upper winding of relay L03 30
to (_).
The picking up of relay L03 energizes the pri
mary indication line circuit over a circuit which
may be traced from the (-1-) terminal of battery
IB (Fig. 1B), lower winding of relay MB, back 35
contact 9| of relay 2SA, primary indication line
conductor IL, back contact 256 of relay L02, indi
cation line conductor IL, front Icontact 356 of
relay L03, back contact 312 of relay SB3, back
contact 315 of relay FP3, lower winding of relay -
L03, resistance 2R3 and secondary indication re
turn conductor IR to the (_) terminal of bat
tery IB.
The closing of the primary indication line cir
cuit picks up relay MB which in turn closes a cir 45
cuit for picking up relay FC at its front contact
34. The pick-up and stick circuits for relay FC
have been omitted from the drawings for the
sake of simplicity, since the detailed operation of
this relay is immaterial for an understanding of
the present invention, it being understood that
the circuits for controlling relay FC can be the
same as disclosed in the above mentioned appli
cation Ser. No. 640,062.
Relay NC is energized, in response to the pick
ing up of relay FC, over a circuit extending from
(-1-), back contact 38 of relay E, conductor I0,
back contact 4| of relay C, front contact 35 of re
lay FC, NC bus 48 and winding of relay NC to
(_). The energization of relay NC applies a 60
conditioning (_) impulse to the primary control
line circuit over the previously described circuit
including front contacts 5D and 54 of relay NC.
It will be assumed that this is a cycle for the
transmission of indications alone (not a duplex
cycle), so that relay C remains down and relay
FC remains picked up for intermittently energiz
ing relay NC by the intermittent operation of
contact 38 of relay E as previously described.
This provides a series of (_) impulses applied to
the primary control line circuit and these im
pulses eiîect the operation of the line relay, the
line repeater relays, the stepping relays and relay
E in the same manner as described in connection
with a control cycle.
75
2,124,846
It is believed unnecessary to point out in detail
how the step-by-step operations in the control
oiîice and at the field stations are effected, since
these operations are the same as already described
in connection with a control cycle, with the above
mentioned exception that the primary control line
circuit is energized with a series of (_) impulses.
This positions the polar contacts of relay F3 at
the repeater station to the left for each impulse,
10 which picks up relay NO3 to repeat a series of
(_) impulses into the secondary control line
circuit.
Relays F3, |F3, NO3, S3 and FN3 all operate in
response to this series of (_) impulses in the
Since relay L03
is picked up during this indication cycle, relay
SA3 is energized in response to the picking up of
relay FN3 over a circuit extending from (+),
front contact 382 of relay L03, front contact 38d
15 manner previously explained.
n of relay FN3 and winding of relay SA3 to (_).
Relay SA3 being slow acting remains up during
the impulsing operations until relay FN3 is
dropped at the end of the cycle for a suniciently
long period to effect the dropping of relay SA3.
Relay FP3 is picked up during the conditioning
“on” period over a circuit extending from (-|-),
front contact 352 of relay L03, front contact 383
of relay FN3, front contact 385 of relay’SA3 and
winding of relay FP3 to (_). Since contacts 382
30' and 385 of relays L03 and SA3 respectively re
main up during this cycle, the intermittent oper
ation of relay FN3 is repeated by relay FP3 be
cause of the intermittent opening and closure of
front contact 383.
Relay MP3 repeats the operations of relay FP3
35.
by contact 318 intermittently opening the ener
gizing circuit for relay 2FP3 which extends from
(-l-), front contact 382 of relay L03 and front
contact 318 of relay FP3 to the winding of relay
2FP3. Relay SB3 is picked up» during the condi
40 tioning “on” period over a circuit extending from
9
the stations in the primary section, but since
this is assumed to be a cycle for the transmis
sion of indications alone these impulses are in
effective to select a primary station for controls.
Likewise, since theseprimary impulses repeat a
series of similar (_) impulses in the secondary
line circuit no station in the secondary section
is selected for controls.
It will be recalled that relay MF3 at the re
peater station Was picked up in response to the
energization of the secondary indication line cir
cuit to initiate the cycle. Relay MF3 is main
tained energized by current flowing over the sec
ondary indication line circuit in series with its
lower Winding until the secondary indication line
circuit is opened at the transmitting ñeld sta
tion by the opening of back contact 412 of relay
SB4. The closure of front contact 412 is in
effective to close the secondary indication line
circuit because the circuit through front con
tact 513 of relay FP4 is open at front contact
699 of relay PF1. Thus relay MF3 is dropped
»during the conditioning “on” period in prepara
tion for its energization or de-energization dur
ing succeeding “on” periods for the reception
of “on” indications from the transmitting ñeld
station.
When relay L03 at the repeater station is
picked up in response to the operation of relay
MF3, it is maintained energized by way of its 30
lower Winding until relay SA3 is picked up to
complete a stick circuit for relay L03 whichv ex
tends from (-1-), front contact 368 of relay L03,
front contact 358 of relay SA3 and upper winding
of relay L03 to (_). Relay L04 at the trans
mitting station is stuck up after the operation
of relay SA4 over a circuit extending from (-1-),
front contact 468'01’ relay L04, front contact
453 of relay SA4, upper winding and front con
tact I155 of relay L04 to (_). The lock-out opl
erations in the primary and secondary sections
will be described later.
(-}-), front contact 385 of relay 2FP3, front contact
3S! of relay L03 and winding of relay SB3 to
(_). Relay SB3 is stuck up throughout this cycle
over a circuit extending from (-l~), front contact
45 31€ of relay SA3, front contact 314 and winding
of relay S133 to (_).
Relay MB in the control oñ‘ice, which was
picked up to initiate the cycle, remains ener
gized over the above described circuit including
the primary indication line circuit, by way ofits
non-pluse in the indication line circuit and a -l
symbol refers to a pulse in the indication line
lower winding and when relay 2SA is pickedfup
during the conditioning “on” period a stick circuit
is completed for relay MB which extends from
(-|-), front contact 66 of relay 2SA, front con
circuit. It will likewise be noted that the regis
tration codes associated with the stations in the
primary section begin with a -{-.
In the ydescription which follows it will be ex
55 tact 5B of relay EFP, front contact 64 and upper
plained how four digitsof code are received in
the control ofñce with only three digits of code
transmitted from station No. 5 in the secondary
section. Referring to the upper left hand por
tion of the typical indication code table of Fig.
5, it will be assumed that code No. 5, which is
associated with station No. 5, is received in the
control oñice in response to station No. 5 initi
ating an indication cycle. Referring to the
lower right hand section of Fig. 5 it will be ob
served that station No. 5 transmits only two
.digits of station registration code With the third
digit (2nd 01T) being used for the transmission
winding of relay MB to (_). This stick circuit
is effective until relay 2FP is dropped during the
ñrst “off” period, when relay MB is de-energized
because the primary indication line circuit is not
60 closed during this period and because the above
described stick circuit is open at front contact
of relay ZFP.
It will be recalled that relay E is picked'
up throughout each “off” period so that the
65 stick circuit for the upper winding of relay MB
is also opened at back contact 65 of relay E. It
will thus be seen that relay MB acts as a start
relay, after which it is dropped or notV during
the first “off” period as determined by the ?lrst
70 “oit” .indication received in the primary indí
cation line circuit being non-pulse or pulse re
spectively.
The first conditioning (_) impulse applied
to the primary control line circuit eiîects the
75 operation of the line- and line repeater relays at
Transmission of indications from secondary
section-_Referring to the layout of Fig. 1, it
will be observed that the station registration ,
codes of all stations in the secondary section
begin with a _. As indicated by the note in
Fig. l, a _ symbol refers to the condition of a
of an indication from the registered station.
50
It
will also be observed that the second and third
digits of the No. 5 station registration code are 70
transmitted in the first “01T” and first “on”
periods respectively and that these digitsv are re
ceived in the control office in the first “on” and
the second “off” periods respectively. As will
be later pointed out the ñrst digit of the No. 5
15
2,124,846V
1O
station registration code is not transmitted but
is registered during the ñrst “ofi” period of the
cycle to complete the code --|-+ which is asso
tion the second indication line circuit with two
non-pulse conditions and the third repeater sta
tion will condition the third indication line cir
cuit With one non-pulse condition.
These non
ciated with station No. 5.
The same discussion applies to other stations
pulse code elements occur automatically and the
in the secondary section, that is, since the code
transmitting can be used to transmit the code
elements from that station on which there is a
possibility of a pulse condition occurring and
When such pulse code elements do occur they are
relayed on through the repeater stations so as to
arrive at the control oñice upon the right half
for each of these stations begins with a -- it
is not transmitted but in effect it is registered
in the control oiiice during the ñrst “off” period.
T'his is possible since for any given size of regis
tration unit, one-half of the total registration
codes necessarily start off with a _ or non-pulse,
and whether this non-pulse is the result of a de
liberate choice or the result or” the inability of the
15 ñeld station to pulse the indication circuit on the
first half-step is immaterial in-so-far as the
correct registration of the station in the oilice
is concerned.
In other Words, the ?lrst code element for each
of the field stations in the secondary indication
line circuit requires a non-pulse and this non
‘pulse is represented in the code table of Fig. 5
showing the codes transmitted from the repeater
station as indicated by the minuses for the ñrst
“off” period. As the repeater station has not re
ceived a pulse element for distant field stations,
it then transmits for such “ofi” period a non
pulse code element and this non-pulse code ele
ment is transmitted because of the open condi
30 tion of contact 39| of relay MF3 in the same
sense that a non-pulse is transmitted by any of
the relays PF for the ñeld stations shown in
Figs. 2 and 4.
To put ,it still another Way, the non-pulse or
the first code element for each of the neld sta
35
tions in the secondary indication line circuit, re
quires no operation on the part of the ñeld sta
tion or on the part 0i the repeater station. But
the repeater station is effective to produce a
non-pulse condition on this ñrst time period
which is allotted on the primary indication line
circuit for the existence of a code element con
dition, and on the same time period, a code ele
ment is transmitted to the repeater station over
the secondary indication line circuit by a pulse
or an non-pulse condition which can be stored
for transmission on the second time period for
the primary indication line circuit. This ar
rangement provides, that although the actual
effect of a distant ñeld station which is repeated
through a repeater station is delayed a half-step,
such delay does not result in the requirement of
added steps by reason of the manner in which
the station selecting codes are arbitrarily chosen
in accordance with the principles of the present
invention.
From the above it follows that for any given
size of registration unit one-fourth of the total
registration codes start ofi with tWo-non-pulses
and these can be used in a succeeding~ third sec
60 tion with no loss of capacity. likewise one
eighth of the total registration codes (in a sys
tem of the proper size) start off with three non
pulses and these codes can be used in a succeed
ing fourth section with no loss of capacity.
Thus, it is seen that for each of the non-pulse
code elements for the stations beyond a repeater
station, a non-pulse code element condition is
set up in the indication line circuit extending
70
from such repeater station by that particular
repeater station. For example, if there are three
repeater stations, the first repeater station from
the control oiiice will condition the primary in
dication line circuit with three non-pulse con
75 ditions; the second repeater station Will condi
corresponding step periods at the ñeld station
step period because of the intervening non-pulse
code elements having; been automatically im
pressed upon the primary indication line circuit. 15
During an indication cycle, indications are
transmitted from a secondary field station, illus
trated in Fig. 4 for example, to the repeater
station illustrated in Fig. 3 by the conditioning
of the secondary indication line circuit. Relays 20
LO4 and S134 remain picked up at the trans
mitting field station throughout the indication
cyle so that the circuit of the secondary indica
tion line, including front contact 412 of relay
SB‘l, can be opened or closed during both the 25
“on” and “oi‘f’ periods as selected by contact
413 of relay FP4 in accordance with the closed
or open conditions of contacts 499 and 49| of
relays PF4 and PB4 respectively.
During each “off” period in the series of im 30
pulses the (-1-) terminal of indication battery
IB1 (Fig. 3) is connected to secondary indica
tion line conductor ILl through the upper Wind
ing of relay MB3 and current flow in the sec
ondary indication line circuit is dependent upon 35
front contact 49| of relay PB4 being closed.
More speciñcally, relay PB4 is the code trans
mitter for the “off” periods of the impulses in the
secondary line circuit. Assuming jumper 480 at
the transmitting secondary station (illustrated in 40
Fig. 4) to be connected to (-i-) as shown, relay
PB“l is picked up during the conditioning “on”
period over a circuit extending from (-|-) , jumper
48D, back contacts 485 and 486 of relays IV4
and 2V4 respectively, front contact 488 of relay 45
FP1, Winding of relay PB4 and front contact 489
of relay L04 to (-). The picking up of relay
P134 provides one of a choice of two “off” indi
cations.
When relay FP4 is dropped during the ñrst 50
“off” period, relay PB4 is stuck up over a circuit
extending from (-|-), front contact 490 of relay
PE4, back contact 488 of relay FP4, winding of
relay PB4 and front contact 489 of relay LO4
to (_). When relay Fl?4 is picked up during the 55
first “on” period the above described stick cir
cuit is opened and the energization of relay PB4
is dependent upon a circuit extending through
front Contact 485 of relay IV4 for the second
“off” indication, to contact 492 of relay T4, which 80
being open illustrates the alternate choice of an
“oit” indication. Relay PB4 will be de-energized
to transmit this alternate choice “off” indication,
With relay PB4 picked up during the condition
ing “on” period and stuck up throughout the ñrst 65
“oit” period as above described, the secondary
indication line circuit is closed as will be pres
ently pointed out. This indication line circuit
was opened .during the conditioning “on” period
70
when relay SB4 opened its back contact 412.
The lock-out period for maintaining relay
LO4 energized extends from the time of the pick
ing up of relay FP4 and the consequent opening
of its back contact 401 until the picking up of
relay SA4 and the consequent closing of its front 75
2,124,846 '
contact 453, during which period relay L04 isv
dependent for its energization on line current re
ceived from battery IB1, at the repeater station,
through its` lower winding. In the event that
some other station superior to the station of
Fig. 4 (in the event that the Fig. 4 station is not
the station nearest the repeater station) opens
the secondary indication line circuit during this
lock-out period, then of course relay L04 ls
dropped and it cannot be picked up again until
the start of another cycle. With relay L04
maintained picked up during the lock-out period,
then when relay SA4 closes its front contact 453,
relay L04 is stuck up over a` circuit including its
15 upper winding and its front contacts 455 and
468 in series with front Contact 453 of relay SA4.
Thus relay L04 is maintained picked up until
relay SA4 dro-ps at the end of the cycle.
v20
During each “on” period the secondary indi
cation line circuit remains open or is closed
depending upon contact 499 of relay PF4. For
example assuming that code jumper 482 is con
nected to (+) as shown in Fig. 4, relay PF4
is picked up during the ñrst “ofi” period over
95 a circuit exten-ding from (-1-), jumper 482, back
contact 494 of relay 2V4, front contact 496 of re
lay VP4, back contact 491 of relay FP4, winding
of relay PF4 and front contact 489 of relay L04
to (_). When relay FP4 is picked up during
30 the ñrst “on” period, relay PF4 is stuck up over
a` circuit extending from (-|-), front contact 498
of relay PF4, front contact 491 of relay FP4,
winding of relay PF4 and front contact 489 of
relay L04 to (_). The above illustrates one
35 choice of an “on” indication whereby relay PF4
is picked up. The other choice “on” indication
is effected by the de-energization of the circuit
including the Winding of relay PF4 and back
contact 491 of relay FP4. The second choice
40 “on” indication de-energizes relay PF4 in the
second “01T” period so that relay PF4 is »down
throughout the second “on” period.
It will now be explained how the conditioning
of relays PB4 and PF4 eiîect the closing and the
45 opening of the secondary indication line circuit
for transmitting indications to the repeater sta
tion where they are received, stored and retrans
mitted to the office.
From the above discussion of the condition
50 lng of the PB4 and PF4 relays it will be observed
that relay FP4 is positioned during an “off” period
in accordance with the indication it is to trans
mit in the next “on” period, while relay PB4
is positioned during an “on” period in accord
ance with the indication it is to transmit in the
next “off” period. Thus on each step taken by
the step-by-step mechanism at the ñeld station,
relays PF4 and PB4 govern the secondary indi
cation line circuit.
60
As Will be later pointed out an indication code
which is started from the station in the second
ary section during the iirst “off” period is not re
ceived in the control oñice until the next or ñrst
“on” period. Therefore the code digit 2+, illus
trated in the lower right hand section of Fig. 5
as being the ñrst code transmitted from station
No. 5, is received in the control oñice as the sec
ond code digit for station No. 5 as is indicated
70 in the upper left hand portion of the indication
code table of Fig. 5. Therefore code jumper 459
conditions relay PB4 to transmit the second digit
of the code associated with station No. 5. It'will
be later explained how the first digit of the-code,
75 that is a non-pulse, registers itself in the con
trol-cnice to complete the station registration
code.
It will be recalled that the secondary indica
tion line circuit was opened during the condi
tioning “on” period by the picking up of relay
S134 and the consequent opening of its back con
tact 412. The dropping of relay 2FP3 at the re
peater station during the first “off” period per
mits current to flow in the secondary indication
line circuit because relay PB4 is picked up 10
throughout this first “01T” period. The circuit for
this current ñow may be traced from the (-1-)
terminal of battery IB1, upper winding of relay
M153, back Contact 391 of relay FN3, back contact
3940i relay FP3, back contact 392 oi’ relay 2FP3,
front contact 399 of relay L03, front contact 396
of relay SB3, secondary indication line conductor
IL1, front contacts 456 and 412 of relays L04 and
SB4 respectively, back contact 413 of relay FP4,
front contact 49H of relay PB4, resistances IR4 20..
and 2R4 in series and indication return conductor
IR1 to the (_) terminal of battery IBl.
This energization of the secondary indication
line picks up relay MB3 to register the first digit
of the »code transmitted from station No. 5 which
is actually the second digit of the station reg-v
istration code. Relay MB3 is maintained picked
up by current in the secondary indication line
circuit until relay lF3 picks up to close a stick
circuit for relay MB3 which extends from (-l-l, 3.(11
front contact 36| of relay BB3, front Contact 390
of relay |F3, front contact 364 and lower wind
ing of relay M133 to (_). Relay MB3 is thus
stuck up throughout the “on” period, following
the “oir” period during which it was picked 35;
up. Relay MB3 is dropped when relay IF3 drops
and opens the above described stick> circuit at
front contact 390.
The picking up of relay FN3 at the repeater
station at the beginning of the ñrst “on” period 40
opens the secondary indication line circuit at
back Contact 391. 'I‘his de-energizes the sec
ondary indication line circuit and when relay
2FP31is-pieked up during the ñrst “on” period
the secondary indication line circuit is again 45
energized because relay PF4 at the ñeld station
is picked up.
' The "energizing circuit for the secondary in
dication line extends from the (-1-) terminal of
battery IBI, upper winding of relay MF3, front
contact 398 of relay FN3, front contact 393 of
relay FPS, front contact 392 of relay 2FP3, front
contact 399 of relay L03, front contact 395 of
relay SBS, secondary indication line conductor
IL1, front contacts 456 and 412 of relays L04 and 55
SB4 respectively, front contact 413’ of relay FP4,
front contact 499 of relay PF4, resistances |R4
and 2R4 in series and indication return conduc
tor IR.l to the (_) terminal of battery IBI. This
eiîects the picking up of relay MF3, which relay
is maintained energized through its upper wind
ing until relay IF3 drops to complete the stick
circuit ‘extending from (-|-), front contact 36|
oi relay SB3, back contact 369 of relay EFS, front
contact 363 and` lower winding of relay MF3
to (_). It will thus be observed that relay MF3
when picked up during an “on” period is stuck
up throughout the following “off” period.
The dropping of relay 2FP3 during the second
“01T” period fails toclose the secondary indica
tion line circuit because of open front contact 49!
of relay'PB‘l. When relay 2FP3 is picked up dur
ing the second “on” period the secondary indica
tion line circuit Ais not closed because of open
front-contact 499fof relay PF4, which relay is down
12
during this “on” period.
2,124,846
It is believed unnec
essary to trace the circuit for the secondary indi
cation line since the energized and de-energized
conditions of this line have been pointed out in
the above typical examples.
Since the secondary indication line circuit is
not energized during the second “off” period,
relay MB3 is dropped during this period when re
lay IF3 drops and opens its front contact 360.
10 Relay MF3 which was picked up during the ñrst
“on”,period is dropped at the end of the second
“ofi” period when relay IF3 picks up and opens
back contact 360.
From the above it will be observed that relay
15 MB3 is selectively responsive during the “ofi”
periods to the energization and de-energization of
the secondary indication line circuit for receiving
either one of a choice ci two distinctive indications,
with the selected choice‘maintained throughout
20 the following “on” period of relay MB3 either
being up or down throughout this “on” period.
Similarly, relay MF3 is selectively responsive dur
ing each “on” period in accordance with one or
another choice of two indications transmitted
25 during each “on” period, with relay Ml.“3 remain
ing up or down throughout the following “off”
period to register the selected indication which
was transmitted and received by this relay.
It will be recalled that relay PB4 was dropped
30 during the first “on’” period after transmitting
the first “off” code digit which was a -1- (pulse).
Relay PB4 is then in condition to be picked up to
transmit an indication during the second “off”
period in accordance with the condition of track
35 relay T4 for example. With relay T4 energized, as
line circuit is dependent upon front contact 39|
of relay MP3. It will be recalled that relay MF3
receives the “on” indications from the station in
the secondary section and since the ñrst “on”
indication has not yet been transmitted to the Ui
repeater station, relay MF3 is down during the
first “off” period and therefore the primary indi
cation line closure cannot be completed. Like
wise relay MB3 which receives “off” indications
from the transmitting station in the secondary
section transmits these “off” indications to the
office during the succeeding “on” periods. There
fore the control ofiice can not complete the clo
sure of the primary indication line circuit dur
ing an indication cycle when indications are be
ing transmitted from a station in the secondary
section.
This means that a _ (non-pulse) will
always be received during the ñrst “off” period
in the control ofûce when a station in the sec
ondary section is transmitting.
20
Relay MB in the control office is therefore the
code receiver for “on” indications transmitted
from the secondary section and relay MF is the
code receiver for “off” indications transmitted
from the secondary section. Relay MB is the code 25
receiver for “01T” indications transmitted from
the primary section and relay MF is the code re
ceiver for “on” indications transmitted from the
primary section. Since these indications trans
mitted from the primary section effect the opera 30
tion of relay MB and MF in the same manner as
the transmission of indications in the secondary
section effect the conditioning of relay MB3 and
MF3 as previously described, it is believed un
necessary to point out how indications are trans
35
mitted from a station in the primary section.
illustrated in Fig. 4, relay PB4 will not be picked
Referring back to the picking up of lock-out
up during the ñrst “on” period. This effects the relay L03 at the repeater station, it will be under
transmission of a -- (non-pulse) code digit dur
stood that the lock-out period for maintaining
ing the second “01T” period. On the other hand, relay L03 energized extends from the time of the 40
if relay T4 is down, then a circuit is completed picking up of relay IF3 and the consequent open
40 through back Contact 492 for picking up relay
ing of its back contact 388 until the picking up of
PB4 during the first “on” period for transmit
relay SA3 and the consequent closure of its front
ting a + (pulse) code digit during the second contact 358, during which period relay L03 is de
“off” period. This is illustrated in the fifth col
pendent for its energization on line current re
umn of the lower right hand section of Fig. 5 by ceived from battery IB in the control oñice and
45 the code digit associated with the second “off”
through its lower winding. In the event that
period being indicated 4.-]- or 0- which are some station in the primary section (which is
the codes transmitted by relay T4 being down or superior to the repeater station) opens the pri~
up respectively.
mary indication line circuit during this lock 50
Transmission 0f indications to control oûice.
out period, then relay LO3 is dropped and it
The above explantion points out how three code cannot be picked up again until the start
digits (see lower right hand section of Fig. 5 table)
of another cycle. With relay L03 maintained
are transmitted from a secondary ñeld station picked up during the lock-out period, then when
during the ñrst “off”, ñrst “on” and second “off” relay SA3 closes its front contact 358, relay L03 55
periods and received at the repeater station dur
is stuck up over a circuit including its upper wind
55 ing the corresponding periods. It will now be eX
ing and its front contact 368 in series with front
plained how these three code digits which Were contact 358 of relay SAS. Thus relay LO3 is main
received and stored on relays MIB3 and MF3 are tained picked up until relay SA3 drops at -the end
retransmitted over the primary indication line of the cycle.
60
`
circuit during the ñrst “on”, second “oiî” and
It will be recalled that the lock-out period for
second “on” periods respectively.
stations in the secondary section extends from the
It will be recalled that the primary indication time that relay FP4 is picked up until the time
line circuit was energized with a start pulse by that relay SA4 is picked up. Since this period
the picking up of relay L03 to initiate the cycle. overlaps the lock-out period of the repeater sta
The primary indication line circuit is de-ener
65 gized during the conditioning “on” period when tion it Will be obvious that a station in the sec
ondary section which initiates the system into an
relay Fl?3 at the repeater station picks up and indication cycle can be ruled out during its lock-`
opens its back contact 315. The closure of front
out period in the event that a station in the pri
contact 312 of relay SB-'f does not energize the mary section takes the line and opens the primary 70
primary indication line circuit because of open indication line circuit back towards the repeater
70
front contact 399 of relay MB3.
During the ñrst “off” period, battery IB (see station.
Recalling that the primary indication line cir
Fig. 1B) is connected to the primary indication cuit cannot be pulsed during the ñrst “off” period
line circuit through the lower winding of relay by a station in the secondary section, this non
75 MB and current flow in the primary indication
2,124,846
pulse or _ code digit effects the dropping of
relay MB during the first “01T” period, which relay
was picked up to initiate the system. With re
lay MB down the ñrst code digit, which is _, is
executed during the ñrst “on” period with iront
contact 8| of relay FP closed. This executing
circuit extends from (B_), back contact 91' of
relay MB, front contact 8l of relay FP, conductor
I8, front contact 31 of relay FC, back contact 55
10 of relay 2V, front contact 58 of relay IV, con
ductor 40 and upper winding of relay IPB to
(B-). Since (B-) is connnected to both termi
nals of the upper winding of relay IPB this relay
remains down to register the first code digit as
15 being _ or non-pulse.
Since it was previously
pointed out that no station in the secondary sec
tion can transmit a -|- or pulse code digit which is
received in the control oilice during the iirst “oli”
period, it will be evident that no station in the
secondary section can pick up relay IPB.
The second code digit is received in the control
oñîce during the ñrst “on” period and is the code
digit which was transmitted 'from the field station
in the secondary section during the iirst “on”
25 period. It will be recalled that this code digit
kpicked up relay MB3 at the repeater station and
maintained it picked up throughout the ñrst “on”
period. The primary indication line circuit is
therefore energized during the ñrst “on” period
30 when relay 2FP picks up and closes its front con
tact 92 and until relay NC drops and opens its
front contact 20. This is because relay MB3 was
maintained in its >picked up .position throughout
the first “on” period so that the primary indica
35 tion line circuit is energized overa circuit extend
ing from the (-|-) terminal of battery IB, lower
winding of relay MF, back contact 22 of relay PC,
front contact 29 of relay NC, front contact 93 of
relay FP, front contact 92 of relay 2FP, front con
tact 99 of relay FC, front contact 9i of relay 2SA,
indication line conductor IL, back contact 256 of
relay L02, indication line conductor IL, front con
tact 356 of relay L03, front contact 312 of relay
SB3, front contact .313 of relay IF3, front contact
399 of relay MB3, resistance units I R3 and 2R3 in
series and indication return conductor IR to the
(_) terminal of battery IB.
Relay MF is picked up over the above described
circuit and is held up by current flowing over the
primary indication line circuit until relay E is
picked up to mark the beginning of the second
“off” period, when a stick circuit is closed for
`relay MF which extends from (-1-), front contact
6B of relay 2SA, front contact 65 of relay E, front
contact 63 and upper winding of relay MF to
(_). When relay E drops to mark the end of the
second “olf” period the stick circuit for relay MF
is maintained complete vat back Contact 69 of relay
4ZFP so that relay MF is not dropped until relay
FP picks up during the second “on” period while
relay E is down. Therefore relay MF is main
tained picked up throughout the second “off”
period to Vexecute the second code digit by means
of `an executing circuit which extends from (B+),
front contaet'96 of relay MF, -back Contact 86 of
relay E?, conductor 9, front Contact 81 of relay
FC, back contact 88 of relay VP, front contact
89 of relay IV, conductor 49 and upper winding
of relay IPF to (B-).
Relay IPF is picked up, and stuck up until the
end of the cycle over its stick circuit which ex
tends irom (-l-), fron-t contact `59 of relay SA,
conductor `112, front contact 5.2 and lower wind
ing'of relay EPF to (_). 'I’he'primary indication
75 `linelcircuit is cle-energized attheïend of the ñrst
13
“on” period by the dropping of relay NC and the
consequent opening of its front contact 2U.
The third code digit to be received in the con
trol oilice is -{- (pulse) in the primary indication
line circuit. This is 'because when relay 2FP
drops during the second “ofi” period to close its
back contact 92, a circuit is closed for energizing
the primary indication line circuit which may be
traced from the (-1-) terminal of battery IB, lower
winding of relay MB, back contacts 23 and 2| of 10
relays PC and NC respectively, back contacts 94
and 92 of relays FP and EFP respectively, front
ccntacts 9S and BI of relays FC and 2SA respec
tively, primary indication line conductor IL, back
Contact 25% of relay L02, indication line conduc
tor IL, front contact 356 of relay L03, front con
tact 312 of relay SBS, back contact 313 of relay
IFB, front Contact SSI of relay MF3, resistance
units I R3 and 2R3 in series and primary indica
tion return conductor IR to the (_) terminal of
battery IB. The primary indication line circuit is
cle-energized when relay NC picks up and opens
the above described circuit at its back contact 2 I.
When the primary indication line circuit is
energized during the second “off” period, relay
MB is picked up and maintained energized by
way of its lower winding until its stick circuit is
closed by the closure of back contact 65 when
relay E drops to mark the end of the second
“oil” period. The picking up of relay 2FP closes
a substitute stick circuit for relay MB at its
iront contact 6I! which is maintained after the
picking up of relay E and until relay ZFP is
dropped during the third “oir” period.
This indication which was received on relay ..
MB in the second “01T” period is executed dur
ing the second “on” period by means of a cir
cuit extending from (B+), front contact 91 of
relay MB, front contact 8| of relay FP, conduc
tor I8, front contact 31 of relay FC, front contact 40
55 of relayZV, conductor 30 and upper winding
of relay EPB to (B-). Relay 2PB is picked up
and closes an obvious stick circuit for itself by
way of its lower winding to (-1-) on conductor 42.
Since the three code digits above described
comprise the station registration code, station
relay 5ST (which corresponds to station No. 5)
is picked up when relay LV is picked up during
the third “01T” period over a circuit extending
from (-i-), front contact 3E of relay LV, con
ductor 26, back contact 24 of relay IPB, front 50
contact 25 of relay IPF, front contact 28 of
relay EPB and winding of relay 5ST to (_).
The transmission of the fourth code digit does
not pulse the primary indication line circuit,
since it was assumed that contact 492 of relay 55
T4 of Fig. 4 is open. It will be recalled that
this fourth code digit was transmitted from the
secondary ñeld station as a _ (non-pulse) be
cause relay PB4 was not up during the íirst “on”
period, which resulted in relay MB3 not being 60
picked up during the second “oir” period. Since
this fourth code digit is retransmitted to the con
trol oiñce during the secondf‘on” period and
since relay MB3 is not picked up during this 65
period, it will be obvious that the primary indi
cation line circuit cannot be energized when the
control oñìce connects relay MF and battery IB
in the primary indication line circuit during the
second “on” period.
70
Therefore relay MF'will remain down in re
spense to this - fourth code digit and when this
code digit is executed it effects the positioning of
-relay IRF to the right by means of a circuit
extending from (B_), back contact St" of relay 75
14
' 2,124,846
MF, back contact 86 of relay FP, conductor 9,
front contact 81 of relay FC, front contact 88 of
relay VP, front contact 98 of relay 2V, conductor
3S, iront contact I9 of relay 5ST and winding
of relay IRF to (CN).
Current iiow in this
circuit positions the polar contact of relay IRF
to the right for displaying the proper indication
that track relay T4 is picked up. It will be ob
vious that the alternate ~fourth code digit is
transmitted when track relay T4 is down, which
finally results in the picking up of relay MF dur
ing the second “on” period so that it is up during
the third “off” period to apply (B+) over the
above described circuit by way of its front con
energy from the secondary indication line circuit
and thus release any lock-out relay in the sec
ondary section that happens to be picked up.
However if relay L03 at the repeater station is
not overruled by a superior station it will remain 5:1
stuck up during the lock-out period by line energy
from the control oflice until its local stick circuit
is established by relay SA3 closing its iront con
tact 358. In case relay L03 of the repeater sta
'tact 95 for positioning the polar contact oi relay
15
IRF to the left.
The above illustrates how the “off” indications
(choice of two) which start from a ñeld station
in the secondary section during one “off” period
are received in the control oflice during the suc
20
ceeding “on” period and executed during the
succeeding “oiî” period. Likewise, examples are
given of the manner in which “on” indications
(choice of two) which leave a ñeld station in
the secondary section during an “on” period are
25 received in the control office during the succeed
ing “off” period and executed during the next
succeeding “on” period.
It is believed that the above examples are suf
iicient to indicate how these code digits are
30
transmitted, stored, retransmitted and executed
for additional steps of a cycle and it will be un
derstood that as many such code digits may be
provided as desired by increasing the number
of steps taken by the stepping relay banks.
35
At the end of the indication cycle the last“off” period is effective to de-energize the SA
and the 2SA relays as well as the VP, the E,
stepping relays and the CD and C relays in the
same manner previously described in connec
tion with a control cycle. Relay FC in the con
trol oflice, which is maintained picked up dur
ing an indication cycle, is likewise de-energized
at the end of the cycle by the dropping of re
lay SA.
Lock-out.---Assuming that a ñeld station in
the secondary section has new indications to
transmit to the control oilice when the system is
in its condition of rest, the field station thus
involved closes the secondary indication line cir
50 cuit and this results in the picking up of relay
45
MF3, followed by the picking up of relay L03 at
the repeater station. The picking up of relay
L03 at the repeater station closes the primary
indication line circuit which picks up relay MB
55 in the control oñice to initiate the operation of
the system.
As a result of this ñeld start the control oñice
applies a conditioning (_) impulse to the pri
mary control line circuit, which (_) impulse is
60 repeated into the secondary control line circuit.
The picking up of relay IF3 in the primary con
trol line circuit opens the pick-up circuit of relay
L03 at back contact 388 and leaves relay L03
stuck up by line energy from the control office
65 over the primary indication line circuit.
In this condition relay L03 at the repeater
station is subject to being locked out or over
ruled by any ñeld station in the primary section
in exactly the same manner as the lock-out be
70 tween individual iield stations of the primary
section.
In the event that relay L03 of the re
peater station is locked out by a superior iield
station (one nearer the control oflice) its release
(since relay IF3 is now picked up during the
75 conditioning period)
will immediately remove
tion is not overruled by a superior station in the
primary section it will maintain energy to the
secondary indication line circuit until after the
lock-out has been eiîected between the individual
stations of the secondary section. Thereafter en
ergy to the secondary indication line circuit is
applied through the pick-up coils of the MB3
and MF3 relays and through the pulsing contacts
of the FN3, FP3 and 2FP3 relays, through front
contact 390 oi1 relay L03 and front contact 396
of relay SB3.
Indication Zine circuit prccharging~--From the
foregoing description it will be observed that the
indication receiving relays MF3 and MB3 at the
repeater station and the indication receiving re
lays MF and MB in the control office are con
nected in the secondary indication line circuit
and the primary indication line circuit respec
tively in such a manner that they are controlled
in accordance with the open or closed condition of
transmitting contacts at the secondary trans
30
mitting station and at the repeater station re
spectively. With such an arrangement it happens
that the sequence of events is such that the
distributed capacity of the indication line circuits
becomes discharged so that the application of
energy to these circuits may result in a temporary
surge of current which is conveniently termed
the charging current. This charging current
ilows irrespective of whether the line circuit is
open or closed at the location from which an
indication is to be received.
It has been found in some instances that the
charging current that ñows into an open circuited
indication line reaches a peak value which is con
siderably greater than the current that normally
flows under the stable conductive condition of the
line circuit and that this charging current surge
lasts for an appreciable length of time. Under
these conditions the message receiving relay in
the indication line circuit, for the purpose of de
tecting the conductive condition of the line, may
be undesirably picked up by the charging current
when such relay was supposed to remain down in
accordance with the open circuit condition of the
line.
During an indication cycle the secondary indi
cation line circuit is impulsed and, in accordance
with the contact arrangement comprising con
tacts 392, 393 and 394 of relays 2FP3 and FP3 of
Fig. 3, a precharge is applied to the secondary
indication line circuit.
During the transfer from one period to an
other, that is from an “on” period to an “oir”
period or vice versa, there is an interval of time
during which the secondary indication line cir
cuit is not energized from battery l'B1 and during
which time the distributed capacity of the sec
ondary indication line circuit may become dis
charged by reason of the closed condition of one
of its controlling contacts at the field station.
This is because the field station apparatus is not
permitted to change the condition of the sec
ondary indication line circuit until after this line
circuit is opened at the repeater station, which is
necessary to provide that the message receiving
55
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