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Патент USA US2126211

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Aug, 9, 1938.
‘
N. D. PRESTON
2,126,211
CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS
Filed Aug. 24, 1935
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Aug. i9, 1938.
N. 0.. PRESTON
’ 2,126,211
CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS
E'iled Aug. 24, 1955
5 Sheets-‘Sheet 2
wZVEEZR 2
. '
Aug» 9, 1938,
N. D. PRESTON
2,126,211
CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS
Filed Aug. 24, 1955
m
_______f\n-1
1.
,
5 Sheets-Sheet 3
‘Aug. 9, 1938.
N. D. PRESTON
2,126,211
_ CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS
Flled Aug 24, 1935
5 Sheets-Sheet 5
Patented Aug. 9, 1938
2,125,211]
A UNITED STATES
PATENT OFFICE ‘
2,126,211
CENTRALIZED TRAFFIC CONTROLLING
SYSTEM FOR RAILROADS
Neil D. Preston, Rochester, N. Y., assignor to Gen
eral Railway Signal Company, Rochester,
. Application August 24, 1935, Serial No. 37,743
‘
5>
‘
9 Claims.
gized and the S line conductor is permanently “
particularly pertains to the communication part
of such systems‘.
station of the series in order to form a closed
In railroad traffic controlling‘ systems the traf~
?c is controlled from a control of?ce usually lo
cated at a central point with respect to outlying
?eld stations, the‘?eld stations being connected
to the control. office by means of the communi
cation system. The location of trains and'the
condition of the traffic controlling devices at re
mote locations (outlying ?eld stations) are indi
cated to the attendant at the control of?ce by
means of indications transmitted to the control
This in
vention is particularly useful in a system which
is called upon to carry out a large number of
controls and indications during a short time.
A single dispatcher can handle the traffic over
2Q a large section of track so that it is desirable that’
15 o?ce over the communication system.
the code combinations be capable of transmission
at such a high rate of speed that the accumula
tion of stored controls and indications is avoided.
The switches and signals distributed through
25 out the territory and those located relatively
near oradjacent each other, together with the
apparatus provided to govern these switches and
signals, are conveniently referred to as compris
ing a ?eld station. The communication system is
30 provided to interconnect the control o?ice with
the several ?eld stations and it is so organized’
that complete control and supervision of the var
ious switch and signal devices at the remote sta
tions are obtained by the operator. 7 Such a traf
35
(01. 1}’7’7-353)
This invention relates to centralized traf?c
controlling systems for railroads and it more
?c controlling system is supplemented by the‘
usual automatic block signal system and other
local means ordinarily provided to guard against
unsafe train movements, improper operation of
track switches or the like.
In accordance with the present invention the
communication system comprises three line wires
‘ extending from the control of?ce through the
several ?eld stations in series. These three line
wires are referred to in this disclosure as the
45 S line, which is the stepping line and the A and
B lines which are the return "line conductors.
The S line, in addition to being used for ‘con
trolling the stepping operations, is used for the
transmission of controls by means of' polar im
pulses from the control o-?ice to the ?eld sta
tions. The S line also is used in combination
with the A and B lines for the transmission of
indications from the ?eld stations to the con
trol office.
" ‘
‘
All three line conductors are; normally deener~
connected to the B- line conductor at the last
circuit path for starting the impulsing opera
tions over the S line from thelcontrol oftlce. The 5
A line conductor is normally disconnected from
the S and B line conductors at the last station of
the series, but is arranged to be ‘connected to
the B line conductor at any station,'having new
indications to transmit, for the purpose of ini
tiating the system from the ?eld station.
The line circuits are so arranged that any ?eld
station‘in the series may so'control the line cir
cuits .that the current in the A line, the B line,
or both the A and B lines builds up at different
rates of time, these rates being provided by the
transmitting ?eld station inserting or removing
inductances from the A line, or the B line or both
the A and B lines.
‘
.
‘
It is fundamental that the inclusion of an in
ductance in an electric circuit prevents current
from rising in this circuit to its maximum value
instantly, that is, a certain lapse of time is re-
quired before Ohm’s law; I=‘E/R. holds unless
the effects of self-induction be eliminated or neu
tralized. The time constant is numerically equal‘
to L/R- and is the time‘ required for the current
to rise to approximately 63% of its Ohm’s law
value. For example, when potential is applied to
a circuit containing one Ohm resistance and one
henry inductance it takes approximately one
second for the current to build up to the above
value.
Advantage is taken of the above mentioned
phenomenon to provide for the selective trans 35
mission of indications from a ?eld station to
the control o?ice in a centralized traffic con
trolling system. The detailed method of trans
mitting indications by the fast or slow building
up of current in the A andB return line’ conduc- ‘
tors of the system will be explained later in th
speci?cation.
‘
'
Since the system is of the coded duplex type,
it is operated through cycles, during each of
which transmission of controls and/or the trans
mission of indications may occur. When con
trols are transmitted, a station selective code is
?rst applied to the line for selecting the par
ticular station with which communication is de
sired and‘then the controls are transmitted to
that station. Similarly when indications are
transmitted, the particular ?eld station trans
mitting such indications ?rst transmits a sta
tion registering code for registering this station‘
in the control office and then the indications are 55,
2,126,211
2
transmitted from this station to the control
o?ice.
'
For the transmission of controls a predeter
mined number of impulses of selected polarities
are applied to the S line for operating the appa
ratus in the control of?ce and at the ?eld sta
tions through cycles of operation irrespective of
the character of the impulses. The distinctive
character (polarity) of the impulses determines
10 the particular station to be selected and the par
in detail, those parts having similar features and
functions are designated in the different ?gures
by like reference characters, generally made dis
tinctive either by the use of distinctive exponents
representative of their location or by the use of U!
suitable preceding numerals representative of the
order of their operation and in which
Fig. 1 illustrates the line circuit arrangement
for the control of?ce and two ?eld stations of a
system embodying the present invention, includ
ticular controls to be transmitted to the selected ' ing only the apparatus most closely associated
station.
.
For the transmission of indications means are‘
provided for energizing the S line during each
15 impulse period by way of lines A and B and caus
ing current to build up slowly or quickly in the A
line alone, in the B line alone, or in both the A
and B lines, for creating four code characters,
any one of which may be selected at each step
of the system for the transmission of indications.
During the energizing'period of the S line circuit,
with the return path established as above men
tioned, it is deenergized at the end of each im
pulse period for causing the stepping apparatus
25 in the of?ce and at the ?eld stations to take their
steps.
'
"
‘
For convenience in describing the operation in
this system the energized or impulse periodsof
the S line circuit will be referred to as the “on”
30 periods, and the deenergized or time spaces be-‘
tween impulses of the S line circuit will be ‘re
ferred to as the “off” periods.
.
A system’ arranged in this manner materiall
increases the capacity for'thev transmission‘ of in
35 dications over the capacity of the system for the
transmission of controls. This is desirable in a
centralized trai?c controlling system.‘ since ‘it
has been found in practice that the number of
indications desired for supplying the" proper in
formation to‘ the operator is greater than the
number of controls necessary.
'
‘
In the present embodiment all line conductors
are normally deenergized. At the start of a con
trol cycle of operations the S line circuit is en
45 ergized with a (+) impulse for conditioning the
various relays of the system in order that the
system may be properly responsive to the follow
ing impulses of the cycle. vThis ?rst energization
of the S line circuit is slightly longer than the‘
other energized periods and is conveniently re
ferred to as the conditioning “on” period.
At the start of a cycle of operations for the‘
transmission of indications, the S line circuit is
energized during the conditioning “on” perod of
the system with a (—) impulse-after which the
stepping operations take place at the control‘
o?ice and the transmitting ?eld station in syn
chronism.
with the line circuits.
Figs. 2A and 2B illustrate the apparatus and
circuit arrangement employed at the control of
?ce for providing means whereby an operator 15
may govern the switches and signals throughout
an extensive territory and whereby indications
may be received from the various ?eld stations
throughout such territory.
Fig. 3 illustrates the apparatus and circuit ar
providing control of a single track switch and for
transmitting indications to the control o?ice in
accordance with the present invention.
Fig. 4 illustrates a modi?cation of the indica 25
tion receiving circuits in the control o?ice; and
Fig. 5 shows in detail the control circuits and
apparatus for controlling relays CD and [LC
shown in Fig. 2A.
When tracing, the circuits, Fig. 2B should be 30
placed below Fig. 2A and Fig. 3 should be placed
to the right of Fig. 2A, with correspondingly
numbered lines in alinement.
ber of “0?5”'and “on” periods determined by the
number of stepping relays inthe bank which in
turn is governed by the size of the system. Dur
ing a duplex cycle the S line is energized during
the conditioning period with a (+) impulse the
same as for a control cycle.
,
'
'
»
'
‘
-Other objects and advantages of the present
invention will be hereinafter set forth, in the
speci?cation and claims and iurther‘details will,
be better understood by referring to the accom
panying drawings which illustrate one method
and one modi?cation for carrying out the inven
tion by way of example.v
Thev drawings illustrate in a diagrammatic
manner the apparatus and circuits employed;v
75 and for convenience in describing the invention
'
For the purpose of simplifying the illustration
and facilitating in the explanation, various parts 35
and circuits have been diagrammatically shown
and certain conventional illustrations have been
employed. The drawings have been made more
with the purpose of making it easy to understand
the operation of the invention than with the idea
of illustrating the speci?c construction and ar
rangement that would preferably be employed in
practice.
The symbols (+) and (—) are employed to in
dicate the positive and negative terminals respec
tively of suitable batteries or other sources of
current and the circuits with which these sym
bols are used always have current ?owing in the
same direction. The symbols (3+) and (B—)
are employed to indicate the positive and nega
tive terminals respectively of a suitable battery
or other source of current having an intermedi
ate tap (CN) ; and the circuits with which these
symbols are used may have current ?owing in one
direction or the other depending upon whether
the terminal (B+) or (B-—) is used in combina
tion With tap (CN).
General description
The conditioning period is followed'by a num60
20
rangements employed at atypical ?eld station for
The three wire line circuit which connects the
control o?ice with the ?eld stations is indicated
in schematic form in. Fig. 1, This ?gure shows
that all three line conductors are normally de
energized.
'
It is to be understood that the system may be
extended to include as many ?eld stations as de
sired; but for convenience in describing the pres
ent invention only a ?rst and‘a last ?eld station
have been illustrated. The S line is connected in
series with the line relays at all ?eld stations in 70
cluding the last'station where this line is perma
nently tied to the B line. The S line includes a
neutral line relay F in the control of?ce and a
three position biased-to-neutral polarized line re
lay F (with suitable exponent) at each ?eld ist'a 75
2,126,211‘
tion.: In the control o?ice the A line is connected
to the (—) terminal of line battery LB by Way of
back contact I5 of starting relay S'I'Ryand the
B line is connected to the (+) terminal of bat—
tery LB by way of back contact ill, of relay STR.
This applies a potential to the A and B line con
ductors so that these conductors may be ener
giiz‘ed by connecting them together at an initiat
ing ?eld station.
10
'
By referring to Fig. 1 it will be noted that in
ductance units AL1 and AL2 are included in the
A line circuit by the picking up of relays PLA1 or
PLA2 respectively, with these inductance units
being short~circuited when the associated relays
is
are not picked up. Inductance units BL1 and BL2
are likewise inserted in or‘ removed from the B
line‘conductor by the picked up or dropped away
condition of the associated PLB relays. As above
‘ mentioned, indications are transmitted by iii
20 cluding these inductance units in or excluding
them from the associated return line conductors.
The A and B line conductors are connected in
series with message relays MA and MB in the
control office; and during the transmission of in
25 dications, the sequential order in which these
message relays are picked up determines the par
ticular indication which is to be received, it‘being
understood that this sequential order is deter»
mined at the transmitting ?eld station by includ
ing the inductance in the associated line or ex
cluding it from this line.
Control office equipment-The control o?ice
(see Figs. 2A and 213) includes a control machine
having a group of control levers for each ?eld
35 station, a miniature track layout corresponding
to the track layout in the ?eld and various indi~
3.
determining relays will be successively energized
during successive cycles in a predetermined order
in accordance with their relative location in the
code determining bank of relays.
An indication change relay ICH (see Fig‘. 5) 5
and an indication code relay iLC are associated
with the bank of storing relays SR and code
determining relays CD for they purpose of provid
ing initiation of the communication system when
a change in condition takes place at any ?eld 10
station or in the control of?ce of the system.
This indication change relay ICH and indication
code ‘relay iCL, together with the storing relays
SR and the code determining relays CD are vasso
ciated with a code stick relay LCS and are so
interlocked with this relay LCS that the picking
up of a CD relay or the ILC relay is prevented
during an operating cycle. The circuits of this
interlocking bank of storing and code determining
relays are shown conventionally by dotted- lines 20
in Fig. 2A and shown in detail in Fig. 5 in the
present disclosure.
. The same means of providing this interlocking
arrangement of the code determining and code
indication relays is also disclosed in applicant’s
prior application Ser. No. 711,383, ?led February
15, 1934, and in the corresponding Canadian
Patent No. 364,307, dated February 2, 1937. For
the purpose of understanding the present inven
tion it is only necessary to ‘understand that relay 30
CD is picked up during a cycle for the transmis
sion of controls to the associated ?eld station,
as well as being picked up during a duplex cycle
when controls are transmitted to the associated
station and indications are transmitted from this
station or some other station during the same
catinglamps or equivalent devices, together with
apparatus and circuits to accomplish the desired
cycle. The relay CD is for instance picked up
by relay SR, and relay SR (see Fig. 5) is picked
operation of the system.
.
up by the depression of push button STB, result
That part of the control o?ice illustrated shows ing in the closure of a pick-up circuit including
40
more particularly the portion of the control ma
this push button contact. Relay SR will then be
chine which is typical of the apparatus associated stuck up through a stick circuit including back
with a single ?eld station having a track switch, ‘contact 2! of the particular relay CD directly
a cross-over or the like, together with the gen
45 eral transmitting apparatus employed for all ?eld
Similarly one‘ or more signal control levers are
associated with this relay SR. With a particular
relay SR energized, and upon restoration of the 45
system to its normal inactive condition, a pick-up
circuit for the relay CD including the back con
tact ‘iii of relay SA, the back contact ‘ll of relay
LCS and the front contact 13 of the relay SR
is closed. With the relay CD energized and its
front contact 26 closed the starting relay STR
also provided, but for convenience these levers
is energized thereby starting the system into
have been omitted since the control of a track
operation. It may be pointed out that the relay
SR which was originally stuck up through a stick
circuit including the back contact 2i of the relay
CD is now stuck up by a stick circuit including
the front contact 2! of relay CD and the back
contact 75 of the relay LCS. Initiation of the
system into a cycle of operation. causes the relay
SA to assume its energized position thereby clos 60
ing a stick circuit for the relay CD including the
stick contact "M of this relay CD and also includ
stations.
‘This apparatus for one track switch comprises
a switch machine control lever SML, a self-restor
ing starting button S'I'B, a miniature track switch
50 its and a track occupancy indicating lamp OS.
switch by lever SML is typical of the control of
55 other types of tra?ic controlling devices.
The movement of lever SML from one extreme
position to the other, followed by the actuation
of button STB results in the normal or reverse
operation of the track switch corresponding to
60 this lever located at the ?eld station correspond
ing to this button. The momentary actuation of
button STB is stored by a storing relay SR (see
Fig. 5) which in turn picks up the associated code
determining relay CD for the associated station.
65 It will be understood that there is a storing relay
and a code determining relay for each starting
button representing a ?eld station. These relays
are so interlocked that irrespective of the number
of storing relays simultaneously picked up in
70 response to the simultaneous or rapid actuation
_ of corresponding starting buttons, only one code
ing the Winding of a series relay LCS. The relays
CD and LCS are therefore stuck up in series in
a stick circuit which is maintained throughout
the cycle of operation of the system. The pick
ing up of the relay LCS as, just explained there
fore results in the opening of the stick circuit for
relay SR and in the deenergization of the relay
SR.
As pointed’ out hereinafter the system is ini-i
70
determining relay for a particular station can
tiated into operation by any one of the ?eld sta~
be energized during any one particular cycle of
tions bypthe picking up of a relay PLA (see Fig. 1)
having an exponent corresponding to that sta
tion. The picking up. of such relay PLA connects 75
operation.
If several storing relays are ener
75 gized. at the same time their corresponding code‘
2,126,211
the A line and the B line together at that station
through the upper winding of a lock-out relay LO.
Since the battery LB is normally connected across
the line wires A and B the closure of the circuit
portion through the upper winding of the lock
out relay LO results in the picking up of this
relay L0 in series with the relays MA and MB in
the control o?ice (see Figs. 1, 2A and 5). Re
ferring now to Fig. 5 it will be noted that the
10 picking up of the relays MA and MB closes their
respective contacts BI and 60, thereby closing
a pick-up circuit for the indication change relay
ICH including these contacts 60 and 6! and in
cluding back contact 10 of the relay SA, this of
course being on the assumption that the system
is then at rest and the relay SA is in its de
energized condition. With the indication change
relay ICH energized a stick circuit including
the stick contact 16 of this relay and including
, _ the back contact 15 of the relay LCS is closed.
With the indication change relay lCI-I energized
by its stick circuit, and assuming that all of the
relays SR are in their deenergized condition, a
pick-up circuit for the indication code relay ILC
including contacts 10, ‘H, T3 and ‘I1 is closed.
With this relay ILC once picked up it is stuck
- up through a stick circuit including its stick con
tact 18, the winding of the relay LCS and the
front contact 1B of the relay SA included in series.
30 The relay ICI-I is of course deenergized when its
stick circuit is broken by the opening of con
tact 15 of relay LCS. The relay ILC isof course
deenergized at the end of the indication cycle
upon restoration of the relay SA to its normal
deenergized condition. When a particular relay
CD is energized the front contacts 36, 48, 52 and
53 connect certain control levers to the system
to cause the application of a polarity code to
the line circuits to control particular apparatus
in the ?eld in accordance with the positions as
sumed by these control levers. If, on the other
hand, the indication code relay ILC is energized
its contacts 34, 42, 43 and 44 result in the appli
cation of a phantom code to the stepping circuit
which code has a polarity characteristic such as
not to select any ?eld station, but to cause op
eration of the stepping relays to enable a particu
lar ?eld station to send an indication code to the
control of?ce.
The control o?ice includes, in addition to the
line relay F above mentioned, a neutral quick
acting line repeating relay FP and a neutral slow
acting line repeating relay SA. Relay FP repeats
each energization of relay F and relay SA is
picked up at the beginning of each cycle, remains
up throughout the cycle and is dropped at the
end of the cycle. Relay SA has such character
istics that its pick up time is relatively long com
pared to the pick up time of neutral relays such
as relay FP, but its pick up time is relatively
short as compared with its drop away time. The
drop away time of relay SA is of su?icient dura
tion to maintain its contacts in their picked up
positions between successive impulses applied to
Code sending relays PC and NC are for the
purpose of providing the proper polarity of ener
gization of the S line circuit during the transmis
sion of the control impulses. With relay PC ener
gized and relay NC deenergized, (+) potential is
applied to line S from battery LB; and when relay
NC is energized with relay PC deenergized, (—)
potential is applied to the S line circuit. For
convenience in the description it will be assumed
that (+) potential applied to line S positions the
contacts of the polar line relays at the ?eld sta
tions to the right, and (—) potential applied to
line S positions these contacts to the left.
Starting relay STR is for the purpose of initiat
ing the system into a cycle of operations in re 15
sponse to a control start, when relay CD picks
up, or for an indication start when relay ILC
picks up. Since relay CD is picked up during a
duplex cycle, relay STR is operated to start the
system irrespective of the type of cycle which
follows.
>
Message receiving relays MA and MB are pro
vided to receive the messages from a transmitting
?eld station and these relays in turn control
message receiving repeating relays MAP and MBP 25.
for registering or storing the received indications
for a period of time suflicient to operate the
selected indication receiving relay.
A timing check relay TC is provided for meas
uring off a predetermined period of time, this 30.
time being ?xed by the adjustment of timing in
ductance unit TL to cause relay TC to pick up
when energized in approximately the same time
that relay F in the S line circuit picks up when
no limiting inductance is in either the A or the B
line conductors. The purpose of this timing
check relay will be explained more in detail later.
For the purpose of illustrating station registra
tion, two pilot relays [PT and 2PT are shown in
Fig. 2B, these relays being controlled on the ?rst ,1
step. It will be understood that similar addi
tional pilot relays may be provided for the second
step and so on until a su?icient number of codes
for vstation registration have been provided as
required by the size of the system. These pilot 4.5
relays are of the two position polar magnetic
stick type, although it is to be understood that
any suitable arrangement of pilot relays may be
employed for selecting station relay ST. Indica
tion receiving relays IIR. and HR are provided for
storing the indications as received by the MAP
and MBP relays at the various steps of the cycle.
These two indication receiving relays are shown
as being selected on the second step of the cycle
and it will be understood that additional similar
relays may be provided for additional steps to ac
commodate the total number of indications to be
received during the cycle.
Indication lamps, such as the track occupancy
lamp OS, are provided to illustrate the manner
in which indication conditions at a particular
?eld station are displayed in accordance with the
present invention.
Field station equipment-The ?eld station il
lustrated in Fig. 3 is typical of all stations of the 65
system and may be adapted for use at the ?rst,
bank of stepping relays including relays IV, 2V second, or any other location by merely altering
and 3V together with the half-step relay VP. . certain code jumpers to arrange for the desired
This bank of stepping relays is for the purpose of codes. For convenience in the description this
marking off the successive steps of each cycle. ?eld station has been speci?cally illustrated as
being the ?rst station of the series by reason of
An impulse controlling relay E is jointly con
the S line circuit as repeated by relay FP.
Associated with the line repeating relays is a
trolled by the stepping relays and the half-step
the distinctive exponents employed.
relay and is for the purpose of energizing and
deenergizing the S line circuit for providing the
A turnout track is illustrated as connected to
a main track by means of a track switch TS1.
75, “on” and “oft” periods of the cycle.
This track switch is operated from one extreme
‘ 2,126,211‘
locked position to the other‘by means of switch
machine
SM1.
‘
.Y.
a‘
‘
.1
.
'
~
_.
Switch machine SM1 is operated by a switch
machine control relay‘SlVfRl of the “two lposition
polar magnetic stick type governed from the. con
trol of?ce through the medium of the communi
cation system herein disclosed. Relay SMR1 con;
trols the operation of'the switch machine by
energizing ‘its normal or reverse operating wires
10 from a local source of‘ current, it being assumed
that the switch machine is operated to ‘its normal
relays 1V1, 2V11and 3V1with the associated half-.
step relay .VP1,. arranged to operate in synchro-‘
nism with the corresponding relays in the control
o?ice. l_ The detailed circuits for the stepping and .
h'alfj-step relays in the control of?ce and at the
?eld station have not been shown, it being con
sidered .su?icient to merely point out in the fol
lowing‘ description ‘when these-lrelaysare ener
gized and deenergized during the “01f” and “on”
periods of a cycle.
The detailed circuits for op
erating thesestepping relay banks may be the
10
locked position when the polar contacts of relay
sameas .disclosed in applicant’s prior application
SMR1 are actuated to'the right‘; and when these
Ser. No. 711,383.
contacts are actuated to the left, the switch ma‘
For the‘ purpose of illustrating the selection of
a. station. for the transmission of controls, relay
SOl has been shown; but it will‘ be understood 15
15 chine is operated to its reverse locked position.
It will be understood that this control preferably
includes suitable approach locking means and
such other automatic signalling circuits as are
usually employed but which are not shown‘in the
20 present disclosure for the sake of simplicity.
. ‘
that any , suitable station, selecting arrangement
maybe employediwithout departing from the
spirit of the present invention. A?eld change
relay CH1 is provided to register a change in any
Suitable signals are associated‘ with‘ track‘ of the traffic controlling devices at the'station 20
switch TS1 for governingtra?ic ‘thereove‘r and
areiprovided with automatic signalling'mea‘n‘s in
‘so that the system will be initiated for thetrans
mission of_ new indications. The detailed cir
terrelatin'g‘ this tra?ic over‘the track switch with a cuit for. controlling this relay has not been shown
since it isimmaterial to an understanding of the
ling ‘devices ‘as may be associated‘ therewith. present invention. It need only be mentioned 25
These signals are likewise governed from-the that relay CH1, normally energized, is dropped in
response to‘ajchange in condition of a device at
control of?ce through the medium ‘of the com
25 such other sections of track and traffic control
30
munication’ system in’ any ‘suitable manner ‘by the station which requires the transmission of
control relays operatedrfrom the control oiiice‘lin‘ indications during a_ succeeding cycle and this
a similar manner disclosedlin connection with
switch machine control relaySMRJ; all of which
has been omitted from‘the present disclosure in
order to simplify the drawings‘ and description.
35 A‘ detector track section having a normally
closed track circuit with the usual track relay
T1 and a suitable track battery ‘are also‘ asso
ciated with the track switch for indicating the
passing of trains. It will be understood that
ceeding change in a traffic device. ’
‘
-. For the purpose of illustrating the manner of
determining when this ?eld station is to trans
mit its new indications, lockout relay L01 is em 35
ployed. When relay L01 is picked up during a
cycle of operations to permit the ?eld station
suitable indicating means are provided in con—
to transmit, the A line indication transmitting
relay PLAl and the B line indication transmitting
nection'with the track switch and the ‘switch ma
relay PLB1 are governed in accordance with the
code jumpers and the indication contacts for this
chine for indicating the locked or unlocke‘dcon
dition- of this apparatus, this portion of; the
system “likewise being omitted from the present
disclosure.
9i
"
“9
-
e
‘ ‘For‘the purpose of indicating how indications
are transmitted by conditioning the A line at
each step of the system, track relay T1 is shown
50
change relay is resensitized or picked up during 30
this cycle in readiness for its response to a suc
with its‘contact picked up andVan‘ explanation
will be given of the-m‘ariner‘in which the picked
station, so that the A and B line conductors are
distinctively conditioned for registering this sta
tion in the control ‘office and for transmitting the
various “indications
45
Inductanceunits AL1 and BL1 are included in
and excluded from the A and B line conductors
respectively-‘by the operation of‘the PLA1 and
PLBl relays.- . By referring vto the dotted rectane
up or dropped away condition of the track relay
gle in ‘the upper right hand portion of Fig. 3 50
is transmittedi‘to the‘contr'ol oi‘?ce by' the ,fast or
slowbuilding up of’ current in the A line‘ con;
it will be seen that similar inductance units are
controlled by similar PLA and PLB relays at‘the
ductor.
other stations ‘ associated with the ‘ system.
For indicating‘) how‘ indications “ are
transmitted over“ the B’lihe‘ conductor‘ at the
. i A resistance‘, B1_ is‘ employed togcompensate for
same step, signal repeating relay M1 is shown
the di?erent locations of the?eld stations during
the functioning ‘of the lookout .feature of the
system. ‘In other words, the ?eld station at the
with ‘its contact in its dropped away-position.
It will‘ be explained how the position-bf this-‘rel
lay ‘is transmitted to the control o?‘ice ‘by-‘the
60 quick or slow‘building‘ up of current invtheB
line conductor at the same step ‘that indications
are transmitted over the A line conductor.“
end of the ‘line ‘needs no such resistance; but at
each station nearer the control o?ice a higher
resistanceis provided so that approximatelythe 60
same current’ from line battery LB in the control
o?ice flows through the lower winding of lockout
The communication part of thesystem includes
the‘ previously‘mentio‘ned- line relay F1 and its
relayirrespective of the particular station which
quick acting “repeating relay-FPl; Slow acting
is transmitting.
relay SA1 is for a purpose similar to that ex
_
v’
-
H
>
“
plained in connection with relay SA in the con
Relays FE“ and SA1 have character
It is believed that‘the nature ‘of the invention,
its advantages and» characteristic features will
best be understood with further description be~
istics similar to the corresponding relays in the
ing set forth fromrthe‘ standpoint of operation.
70 control oi?ce; but in order to prevent unneces
sary stepping operations at stations not selected,
the circuit arrangement of‘ these relays is differ
ent from the corresponding control relays as will
be later pointed out.
i 1
a
The .‘?eld station includes a bank of‘ stepping
'
‘
‘Operation
‘
r‘
‘
70
‘ The'system of the present invention is nor
mally in a condition of rest from whichit may be
initiated into a-l‘cy‘cle of operations either from
the control office or from~any one‘ of the?eld
stations when; there are newhbontrols or‘ new
6
2,126,211‘
indications respectively ready ‘to be vtransmitted.
If new controls for several‘different ?eld stations
are ready for transmission at substantially ‘the
same time, they are transmitted on separate
cycles, one station for each cycle. Similarly, if
several ?eld stations have indications ready for
transmission at the ‘same time, they are trans
mitted from ‘such ?eld ‘stations to the control
office, one station for each ‘cycle.
It may happen that there are new controls and
M1
new indications ready to be transmitted at the
same time, ‘and in such instances controls are
transmitted to a selected ?eld station simultane
ously with the transmission of indications from
the same or some other ?eld station during the
same cycle.
Irrespective of whether a cycle is to be for the
transmission of controls and/or the transmis
sion of indications, a predetermined number of
29 impulses are placed upon the S line circuit to
accomplish the step-by-step operation of the step
ping relay banks. These impulses are time spaced,
that is, they follow each other at de?nite time
intervals. Conditioning takes place during the
period of time that the S line circuit is deenerg
ized between impulses (“off” periods). In other
words, during the “off” periods, the desired con
trol and message relays are selected; and during
the succeeding “on” periods, the selected circuits
30 are energized in accordance with the particular
code combination applied to the line during these
“on” periods.
'
When a cycle is initiated for the transmission
of controls, the character of the impulses placed
upon the S line circuit is determined in accord
ance with the station to be selected and the con
trols to be transmitted, as set up by the code
jumpers and the control levers for that particular
station. During a cycle of operation initiated for
the transmission of indications alone, the char
acter of the impulses placed upon the S line cir
cuit is such that no station will be selected, but
these impulses merely cause the step-by-step
operation of the control o?ice stepping relay bank
and the particular ?eld station which is trans
45
mitting. A series of impulses which selects no
station for an outbound call is referred to as a
phantom code.
-
When a cycle of operations is initiated from a
?eld station for the transmission of indications,
the plurality of impulses placed upon the S line in
the control office to cause the step-by-step opera
tion are returned to the control o?‘ice by way of
. one or the other of the A or B line conductors or
the A and B line conductors in multiple, with the
55
rate at which current is allowed to build up in
the A and B line conductors determining the in
dications which are to be transmitted.
Normal at rest c'onditions.—-Although the sys
60 tem may be initiated from the ?eld stations, the
three wire line circuits are normally deenergized.
In order to provide a means for initiating the sys
tem from a ?eld station, the normally deenerg
ized A-—B line circuit is energized ‘m a manner
which will be later pointed out. The remaining
65 circuits of the system’ are likewise normally de
energized, with a few exceptions.
For example, the track circuit associated with
track switch TS1 is preferably of the closed cir
cuit type so that relayT1 is normally picked up.
70
Also, the ?eld change relay OH1 is normally ener
gized over a circuit not shown.
.
Manual»start—With'the system in a condition
of rest, it- may be manually initiated into a cycle
75. for the transmission of controls. Whenever such
a cycle
desired the operator ?rst positions the
control levers for the ?eld station which he de
sires'to select-and then actuates the starting but
tonivSTB associated with the station.
‘ Forithe purpose of considering the operation of ti
the present systemit will be assumed that lever
SML=of Fig. 2A is positioned to the right for
operating the track switch of Fig. 3 to its normal
locked position and that the starting button
STB is actuated to start the cycle of operations. 10
The actuation of button STB causes relay CD to
be picked up and stuck up until the end of the
cycle which is initiated by the picking up of relay
CD.
A circuit is now closed for picking up relay
STR which extends from (+), front contact 26
of relay CD and winding of relay STR. to (—) . A
circuit is now closed for picking up relay PC
which extends from (+), back contacts 39, 38
and 31 of relays 3V, 2V and IV respectively, front 20
contact 36 ofrelay CD, winding of relay PC and
front contact 33 of relay STR, to (—).
The picking up of relay PC applies the ?rst
conditioning impulse to the S line circuit (which
in this event is positive) over a circuit which may
be traced from the (+) terminal of battery LB,
front contact I2 of relay PC, back contact l3 of
relay NC, winding of relay F, back contact 32 of
relay E, S line conductor l8, winding of relay F1,
through the line relays at other stations, wind 30
ing of relay F2 at the last station, back contact
304 of relay PLB2 at the last station, back con
tact 204 of relay PLB1 at the ?rst station, B line
conductor l9, winding of relay MB, front con
tacts l4 and I5 of relay STR, back contact I6 of
relay NC and front contact 25 of relay PC to
the (—) terminal of battery LB. It will be noted
that the A line conductor is not energized at this
time because of the open front contact on the
SA2 relay at the last station, which relay is not 40
yet picked up.
In response to this energization of the S line cir
cuit, relay F in the control of?ce is picked up and
the line relays at the ?eld stations, including re
lay Fl, actuate their polar contacts to the right.
The picking up of relay F closes a circuit at
its front contact 40 for energizing relay FP. Con
tact 200 of relay F1 in its right hand position
closes a circuit for picking up relay FP1, which cir
cuit extends through back contact 20I of relay
SAl.
At the same time this circuit extends
through back contacts 202 and 201 of relays L01
and S01 respectively and winding of relay SA1 to
(—) for energizing relay SA1. '
It will be understood'that the line repeating
relays, including the slow acting relays, at the
other stations along the line are picked up sub
stantially in synchronism with corresponding re
lays at the ?rst station illustrated in Fig. 3. When
relaySA2 at the end ?eld station closes its front
contact 306 (illustrated in the dotted rectangle in
the upper right hand portion of Fig. 3), the A line
conductor is connected in multiple with the B
line conductor so that current returns to the con
trol'o?ice over these two conductors in parallel. 65
When the B line conductor was energized at
the beginning of this conditioning “on” period
over the above described circuit, relay MB was
picked up and when the A line conductor is
energized a little later in the “on” period, relay
MA is picked up. It will be noted that front
contacts l4 and I5 of relay STR in the control
o?ice connect the A and B line conductors in
multiple at the control of?ce end of the circuit.
’ The picking up of relay MB closes a circuit for
O
2,126,211:
‘picking up‘relay MAP at this time, which circuit
extends from (+), front contact 50 of relay MB,
back contact 5| of relay MA and winding of
relay MAP to (—). Relay MAP closes a stick
circuit for itself which extends from (+), back
contact 55 of relay E, front contact 54 and wind~
ing of relay MAP, to (—). Since the‘ channel
selecting circuits (see Fig. 23) to which the (3+)
and (13-) contacts on the MAP relay connect.
are not yet selected, this. operation of. relay MAP
is of no effect. When relay‘ E; is picked up to
mark the end of this conditioning “on” period
(as will be later described), the above described
stick circuit for relay MAP is opened at back
16: contact 55 and this relay is deenergized, before
relay IV is picked up to make the selection of the
?rst channel circuit.
‘During the conditioning “on,” period, relay SA
in the control oflice is energized over a circuit
20 completed at front contact 4| of relay FP.‘ Dur
ing this period, relay SA1 at the station is ener
gized over the above described circuit including
contact 209 of relay F1 and also at front contact
298 of relay FPl.
‘
Polarity selection of stepping impu‘Zses.—When
the system is initiated by the picking up of relay
STR due to a manual start condition, the ?rst
impulse placed upon the S line circuit is positive
in character by reason of- the picking up of relay
PC as previously described. This. application of
energy to the S line circuit causes various relay
operations, a portion of which have been de
scribed, while that portion of the relay opera
tions relating to the half-step relay and the
stepping relays will be pointed out later.
It will be assumed for the present that after
a predetermined time the S line circuit is de
energized by the picking up‘ of relay E. This
deenergization of line S results in the energi
40 zation of the ?rst steppingrelay IV. The pick
ing up of relay IV opens back contact 31 in
cluded in the above described pick up circuit for
relay PC and closes front contact 37, which will
again energize relay PC during this “off” period
over the previously described circuit from (+)
which now ‘extends through front contact 31 of
relay IV, front contact 48 of relay CD, code
jumper ?ll in its full line position, winding of
relay PC and front contact 33 of relay STR, to
iii)“ (m). This picking up of relay PC determines
that the character of the next impulse will be
(+) and the line circuit is energized in the same
manner as described for the conditioning (+)
impulse.
'
In the event that code jumper 41 is connected
in its dotted line position, then the circuit through
front contact 48 of relay CD is effective to pick
up relay NC which, by means of its contacts l3
and it being picked up and contacts 12 and 25
(30 of relay PC being dropped, reverses the connec
tion of battery LB to the line circuits so that
line S is energized with a (—) impulse. Such
control of relays- PC and NC upon the picking up
of relay IV occurs during the ?rst “off” period,
that is, during the deenergized condition of the
stepping line circuit following the initiating “on”
period.
,
After the ?rst impulse has beenconnected to
the control line circuit for a predetermined pe
riod of time, the line is again deenergized by the
picking up of relay E. Such deenergizaticn of
the S_ line causes the second step to be taken by
picking up» relay 2V. Relay 2V closes a circuit
for picking up relay NC which extends from
‘ (+),‘ba‘ck contact 39 of relay 3V, front contact
7
38 of relay 2V, front contact 52 of relay CD,
jumper 49 in its full line position, winding of
relay NC and front contact 33 of relay STR, to
(—-). It will be obvious that relay PC would be
picked up on this step in the event. that code
jumper 49 is connected in its dotted line position.
The code which is selected for the third step
in the present embodiment is determined by the
position of lever SML. With this lever in its
right hand position as. shown, relay PC is ener 10
gized on the third step over a circuit extend
ing from (+), front contact 39 of relay 3V, front
contact 53 of relay CD, contact of lever SML in
its right hand position, winding of relay PC and
front contact 33 ‘of relay STR, to (—). This
p-redetermines that a (+) impulse is applied to
line S during the third “on” period. In the event
that lever SML is in its left hand‘ dotted position,
then relay NC would be picked up to apply a (—)
impulse to line S during the third “on” period.
20
This operation occurs on each step so that re
lays PC and NC are selectively energized in ac
cordance with the particular code which, is to
be transmitted for each step. During the ?rst
part of each operating cycle, these relays are 25
energized during the station selecting steps of
the stepping relay bank in accordance with the
character of the code for the station desired
to be selected. During the remaining steps of
the cycle these two relays are selectively ener
gized in accordance with the positions of the
control levers associated with the selected station.
It will be understood that additional levers for
the control of signals or the like may be pro
vided and selected through additional contacts ..
on relay CD for selectively energizing the PC and
NC relays during additional steps (not shown)
of the cycle.
From the above it will be seen that the impulses
applied to line S always begin with a (+) im 40
pulse for a cycle initiated from the control o?‘lce,
while the following impulses are (+) or (—)
dependent upon the code jumpers and control
levers rendered effective by the particular code
determining relay‘ which is picked up for that
cycle. Also this polarity determination is ac
complished by the two code sending relays PC
and NC selectively energized at the ‘several steps,
with the changes in selection occurring while
the S line is deenergized.
Impulsing and stepping operations-irrespec
tive of the particular polarity with which stepping
line S is energized, relay F in the of?ce is picked
up and the F relays at the various ?eld stations,
are actuated either to their right or left hand .
positions for picking up their associated FP re
lays. For example, the closure of contact 209
of relay F1‘ in either its right'or left hand position
closes a circuit through back contact 2M of
relay SAl for picking up relay FPI. The ?eld
station stepping circuits in the present embodi
ment are so arranged that stepping is discon~
tinued at ?eld stations not selected. This is
determined by relays L01 and S01 (of Fig. 3, for
example), either one, the other or both of which
will be picked up as long as this station remains
in active communication with the line circuit.
This feature will be more speci?cally pointed out
later, but for the present it is to be noted that
relay FPl' acts as a repeater of relay F1 as long 70
as either front contact 202 of relay L01 or front
contact 20'! of relay S01 is closed. Therefore it
Will be assumed that relay FP1 of Fig. 3 repeats
all of the impulses applied to the line circuit
during this assumed cycle of operations. This is 75
2,126,211
8
because relay S01 at this particular ?eld station
will be picked up throughout the cycle in a man
ner to be later described.
As above mentioned the detailed circuits for
CI
operating the step and half-step relays are not
shown in this disclosure, it being considered suf
?cient to merely point out when these relays are
energized and deenergized. At the beginning of
the transmitting part of the cycle, marked off by
10 the picking up of relay SA in the control of?ce and
similar relays at the ?eld stations, the half-step
relays including relay VP in the of?ce of relay VP1
at the illustrated ?eld station, are picked up for
preparing the stepping relay circuits for the ?rst
step, which step is taken during the next “off”
period. In brief, the half -step relays VP and VP1
are picked up and dropped alternately and in
synchronism by the successive energizations of
the stepping line circuit and the stepping relays
are picked up in succession for each successive
deenergization of the stepping line circuit. This
means that the VP relays ?rst pick up during the
conditioning “on” period, then drop during the
?rst “on” period, are again picked up' during the
second “on” period and dropped during the third
“on” period. Since three steps are assumed in the
present embodiment, the VP relays remain de
energized after dropping during the third “on”
period. Likewise, the IV relays pick up during
the ?rst “off” period (following the conditioning
“on” period), the 2V relays pick up during the
second “off” period and the 3V relays pick up
during the third “off” period, with these relays
being stuck up until the end of the cycle.
When relay VP is picked up during the condi
tioning “on” period, a circuit is closed for pick
ing up relay E which extends from (+), front
contact 90 of relay MA, front contact 9| of relay
MB, front contact 92 of relay VP, back contacts
40 93, 94 and 95 of relays IV, 2V and 3V respective
ly and winding of relay E, to (—) . Relay E
closes a stick circuit for itself by way of its front
contact 96, front contact 9'! of relay SA and over
the remainder of the previously described circuit
to the winding of relay E. It will thus be seen
that the energization of relay E to mark the end
of an “on” period is dependent upon the energiza
tion of both the A and B line conductors which
causes relays MA and MB both to be picked up.
In response to the picking up of relay IV during
the ?rst “off” period, the above described pick up
and stick circuits for relay E are opened at back
contact 93 of relay IV which allows relay E to
drop. It will be obvious that the opening of back
contact 32 of relay E terminates the conditioning
“on” period by deenergizing the S line circuit, and
likewise the closure of this back contact when
relay E drops terminates the ?rst “off” period by
energizing the S line circuit.
When relay VP is dropped in response to the
?rst impulse, relay E is picked up over the above
described pick up circuit which now includes back
contact 92 of relay VP and front contact 93 of re
lay lV. Relay E again closes its previously de
scribed stick circuit.
'
When relay 2V picks up in response to the sec
ond “off” period, the above described circuit for
relay E is interrupted at back contact 94 which
allows this relay to drop and again energize the S
relay 2V. Relay E deenergizes the S line circuit
at back contact 32 and closes its above described
stick circuit.
When relay 3V picks up in response to this
third deenergization of the S line circuit, the
circuit of relay E is opened at back contact 95,
allowing relay E to drop and again energize the
S line circuit.
When relay VP drops in response to the third
impulse, relay E is energized over the above de 10
scribed circuit which now includes back contact
92 of relay VP and front contact 95 of relay 3V.
Relay E opens back contact 32 for deenergizing
the S line circuit and again closes its stick circuit.
Since there are no more stepping relays the 15
above described stick circuit for relay E is main
tained complete for a comparatively long interval
of time which maintains the S line circuit de
energized for a sui?cient period of, time to drop
the SA relays to mark the end of the cycle.
The dropping of relay SA deenergizes the stick
circuits for the stepping relay bank which al
lows the stepping relays to be released. The open
ing of front contact 91 of relay SA deenergizes
the stick circuit for relay E which allows this
relay to be released. The opening of front con
tact 10 of relay SA (see Fig. 5) opens the stick cir
cuit for relay CD including winding of relay LCS
in series. Similarly, the dropping of the SA relays
at the field stations deenergizes the holding stick
circuits for the stepping relays at the station at
which these relays have been operating during
this cycle. It will be understood that relay CD is
deenergized by the dropping of relay SA and this
relay in turn deenergizes relay STR and the cir
20
25.
30
35
cuits leading to the PC and NC relays are like
wise opened by the dropping of relay CD.
It will be understood that relays MA and MB
are picked up and dropped substantially in syn
chronism with relay F during a control cycle and 40
since these relays are dropped at substantially
the same time and picked up at substantially the
same time, the circuits are not completed for en
ergizing repeating relays MAP and MBP. The
energization of these repeating relays will be ex 45
plained in connection with an indication cycle.
With relays MAP and MBP deenergized at each
step of the control cycle the executing circuits
shown in Fig. 2B are effective to position pilot
relays IPT and 2PT to the left because the ener
gizing circuits for these pilot relays extends from
(B—) at back contacts of relays MAP and MBP.
With the contacts of relays [PT and 2PT both
positioned to the left no station relay is selected.
In other Words, a combination of quick energiza 55
tion of the A and B line conductors during the
station registration steps of the cycle corresponds
to a phantom code and results in the selection of
no station relay. After the station selection steps
are taken, then with no station relay picked up 60
the following steps are ineffective to energize any
of the indication receiving relays because of the
open front contacts on the station relays.
It is to be understood that these circuit con
nections may be extended for as many steps as 65
desired, with alternate “off” periods picking up
additional stepping relays and alternate “on” pe
riods shifting the BP relays in a manner similar
to that already described.
The stepping relay banks at all of the ?eld 70
line circuit which was deenergized when relay E '
stations are substantially identical with the one
opened its back contact 32.
c
When relay VP picks up in response to the sec
ond impulse, relay E is again energized over the
above described circuit which now includes front
75. contact 92 of relay VP and front contact 94 of
illustrated in Fig. 3. The operation of the ?eld
station stepping relay bank is effected by the
intermittent operation of relay FP1 in a manner
which is indicated by the connection through 75
2,126,211
back contact‘ 2090f relay FP1, front contact 209
9,
Since the picking up of relay S01 registers the
of relay SA1 and the dotted line leading to the ‘ fact that a (+) impulse was transmitted during '
stepping‘ relay bank. As above pointed out the
the conditioning “on” period, the stepping relays
intermittent operation‘ of a relay» FP1 (and similar ‘
at the station illustrated in Fig. 3 complete their
operations, While at those stations not to be se- '
5n relays at other stations) is dependent; upon relays L01 and S01. Therefore after relay 8A1
tions where both the L0 and SO“ relays are de
energized, are not operated with the result- that
1 0% "the stepping operationatlv these stations does‘not‘
take place.
Stationv selection for controlsz-ll‘he applica~
tion of a predetermined‘ number of impulses of
selected'polarities to the S line‘circuit to comprise
1 5kja cycle of operations has been explained in detail.
For the transmission of controls the first" impulse
is alwayspositive in character, with thefollowing
impulses positive or negative in accordance with
the particular code jumpers and control levers
2 Ouwhich are effective for the cycle. Referring to
Figs. 1 and 3 it will‘be obvious that‘ these impulses
are received at all of the ?eld stations since the
?eld station line relays are all‘ included in the
elected, the stepping relay- operation is discon
tinued when the SO relays at‘ those stations drop
out to effect the opening of‘ the FP relay circuits
at front contacts similar to ‘261" of the various
S0
relays.
'
'
'
‘
At the station illustrated in Fig. 3; relay ‘FP1
lay VP1 is picked up during the conditioning “on”
period over a circuit which is not shown.
As pointed out above the character of the ?rst
impulse (following the conditioning “on” period) ,20
is determined in accordance with the position of
jumper 4‘! in the control of?'ce. With this jumper
connected as shown in Fig. 2A, a (+) impulse is
stepping‘ line circuit. However, for convenience
describing the operation of‘ station selection
applied to the stepping line circuit which posi~
reference will be made to Fig. 3 which illustrates
a typical ?eld'station somewhat in'detail and
whichfor convenience-is considered the first’ sta.
stick circuit for relay so1 which extends from
2 5111111“
tion of the series.
305.: The ?rst (+) impulse in'the stepping line actu~
ates the'polar contacts of relay F1 to the right.
The closureof contact 200. closes a pick up circuit
for relay FTI which‘ extends from (+), contact
200. in itslright hand dotted position, back‘ con
3 5'-,,tact ZUI of relay SA1 and winding of relay FP1,
to (—). The closure of contact 290‘ also estab
lishes a pick up circuit for relay-SA1 which ex
tends throughback contacts 262 and'Zill of? relays
L01 and‘: S01, respectively, in series.‘ The closure
4Or~of front contact 208 of relay FP1‘ establishes a
direct energizing circuit for relay SAI‘ and since
it is‘assumed that the ‘station illustrated in Fig. 3
is the station to be selected‘duri‘ng this cycle; relay
FP1 williintermittently. close its front contact 286
45;;for maintaining relay 3A.1 picked up throughout
the cycle.. It is to‘be understood that the ?rst
impulse (conditioning “on” impulse) is somewhat
longer thantheremaining impulses ofv the cycle
so that relay SA.1 and‘other similar relays at other‘
50, stations have time to pick up during the time that
the stepping line circuitis energized.
Duringthe conditioning “on” period,trelay S01
is energized over. a circuit extending. from.(+),
back contact 21!! of relay SAI, back contacts 2|2‘,
55%;; Band 2 llliofirelays 3V1, 2V and W1 respectively,
contact 2“ of relay F1 in its right hand dotted
position andwinding‘of relay S01,‘ to (‘—> . Relay
S01 connects (+) by way of its front contact
M5 to the above described. circuit independent
6050f‘ back contact 210“ of relay SA1, which. main
tains relay S01 energized after the picking up of
relay. SAL It will be understood that similar cir
cuits are established at all other ?eld stations for
picking up the associated SO relays and that the
(5)Msame operations take place at these other vstations
“ with‘ exceptio-nsrlater to‘ be explained.
It the conditioning impulse is‘ (—) for reasons
to-be later explained, the polar contacts of relay
F1 are positioned to the left which prevents the
ouenergization of relay S01, since the above de
scribed pick up circuit is open with contact 2H
in.1 its- left‘ hand dotted position, and since the
pickup circuitvof relay S01 is‘interrupted after
contact 2"] of: relay SA1‘is shifted from its back
7 5 .- ‘t‘o itstfront position”
10.,
repeats the operations of‘ relay F1 by means of a
circuit which extends from (+), contact 2'65] of
relay F1 in either of its dotted line positions, back
contact 202 of relay L01, front contact 267 of
relay S01, and winding of‘relay FP1, to (-—) . Re
tions relay F1 to the right and closes a selecting 25
(+), front» contact 215 of'relay SO1 back con
tacts 2|2 and 2| 3 of relays 3V1 and 2V1 respec
tively, front contact 2l4‘of relay IV1; co'de jumper
2H5 in its full, line position, contact Z‘ll of relay 30“
F1 in its rig-ht‘ hand‘? dotted position and winding
of relay S01, to (—).
If 'code jumper “is connected in its dotted line
position, then a (—) impulse is applied to the
stepping line because this position of the ?rst code 35
jumper effects the energization of relay NC in»
stead of relay PC, which is effective to actuate
the contacts of relay F1 to their left hand dotted
positions. With contact 2“ of relay F1‘ in its
left hand dotted position, then the circuit leading
through the contacts of the stepping relays to
jumper H6 is not completed‘to the winding of
relay S01 so that this relay is dropped in response
to a code combination comprising a ?rst (—)
impulse.
Similarly, with the ?rst impulse (+) at those 45
stations with code jumpers similar to 2“; ar
ranged as shown by the dotted line connection of
this code jumper, the circuits to the SO relays
are incomplete so that they are dropped out.
The opening of a contact similar to contact 201
of those stations which fail to be selected discon
nects the circuit leading to the relays similar to
FP1 so that stepping does not occur at such sta
tions.
,
During the “off” period following the ?rst 55
“on” period, stepping relay 2V1 is picked up and
the polar contacts of relay F1 are restored to
their neutral positions. This deenergizes relay
FP1 and since relay S01 remained picked up dur»
ing the ?rst “on” period'a stick circuit is now
completed for this‘ relay which extends from
(+), front contact 2l5 of relay S01, front con
tact 2H] of relay SA1, back contact Eii'i of relay
FF1 and winding of relay S01, to- (—).
Upon the application of the next impulse which
follows the picking up of‘relays 2V and 2V1, relay ‘
F1 is positioned to the left because this impulse is
(—) as determined by code jumper 49 in the con
trol oilice being connected to‘the NC bus which
70
leads to relay NC. This'(‘—) impulse establishes
the selecting circuit for relay SO1 which extends
from (+) , front contact 2l5 of relay S01, back
contact 2l2 of relay 3V1, front contact 2K3 of
relay 2V1, code jumper 222 in its full line posi 75
10
2,126,211
tion, contact 2| I of relay F1 in its left hand dotted
position and winding of relay S01, to (—).
From the above it will be apparent that relay
S01 at the station to be selected is energized by
means of its selecting circuit including code
jumpers H6 and 222 and contact 2“ of relay F1
in either a right or a left hand dotted position
during the impulse or “on” periods of the station
selecting portion of the cycle. Make-before
10 break contact 2!! of relay F1 establishes a stick
circuit for relay SO1 during the “off” periods,
which extends from (+), front contact N5 of
relay S01, front contact 2 IU of relay SA1, contact
2| I of relay F1 in its neutral position and winding
of relay S01, to (-—). Contact 2“ in its neutral
position is in multiple with back contact 2H of
relay FP1 so that the stick circuit for relay S01
is established immediately upon the opening of
the selecting circuit by contact 2H and before
relay FPl is deenergized to close its back con
tact 2".
In brief there are a plurality of code determin
ing means in the control oflice each including a
code determining relay and a set of code jumpers,
only one of which relays may be effective to de
termine the character of the impulses of any
particular cycle. During the ?rst part of the
cycle the station selecting relays (such as relay
S01) at each ?eld station are selected in accord
30 ance with the positions of the code jumpers
which are effective for that cycle of operations.
At each ?eld station a different combination of
code jumper connections is provided so that each
station requires the reception of a distinctive
code in order that this station may be selected
and this code is determined in accordance with
the positions of the corresponding group of code
jumpers in the control oflice.
With the use of two separate code jumpers in
the o?ice and at each station as illustrated, four
different code combinations are possible, three of
which may be employed for station selection with
the fourth used for the phantom station code
call. It is obvious that the code call for the sta
tion illustrated in Fig. 3 is (+) (-—) because code
jumpers 2 l6 and 222 at the station are connected
for relay S01 to be maintained in its energized
position in response to a (+) and a (—) impulse
on the ?rst and the second steps, respectively,
which positions contact 2H of relay F1 to the
right and to the left in response to these ?rst two
60
This energization of relay SMR.1 positions its
polar contact 224 to the right for applying energy
to the normal operating winding of switch ma
chine SM1 for operating the track switch to its
normal locked position.
In the event that lever SML is in its left hand
dotted position, then a (—> impulse is applied to
the stepping line for actuating the contacts of
relay F1 to the left, thus closing a circuit for
energizing relay SMR1 by way of its lower wind 10
ing, which extends from (+), front contact 2l5
of relay S01, front contact 2i2 of relay 3V1,
contact 2“ of relay F1 in its left hand dotted
position, front contact 2!!! of relay 3V1 and lower
winding of relay SMR1, to (—). Since the con 15
nection to the lower winding of relay SMR1 is
in opposition to the upper winding, contact 224
is actuated to its left hand dotted position for
applying energy to the reverse operating winding
of switch machine SMl which operates the track 20
switch to its reverse locked position.
In a similar manner additional steps may be
provided for transmitting additional controls to
the illustrated ?eld station for governing the
signals or such other controls as may be nec
essary.
25
End of control cycZe.—Fo1lowing the applica
tion of the last impulse to the S line circuit, relay
E is maintained energized for a period of time
which is sufficiently long to allow relay SA to 30.
restore its contacts to their normal positions.
This is due to relay E opening the stepping line
circuit at back contact 32 for a comparatively
long interval of time. Relay SA1 at the illus
trated ?eld station and other similar relays at 35
other stations are likewise restored to their nor
mal positions.
Upon the opening of the front
contacts of the SA relays in the control o?ice
and in the ?eld stations the stick circuits for the
stepping relay banks are deenergized which al
lows these relays to restore to normal. It has
previously been explained how the other relays
in the control o?ice are deenergized at the end
of the cycle. Relay S01 at the selected ?eld sta
tion is deenergized because contact 2“ of relay 45
F1 is in its neutral position and front contact 2l2
of relay 3V1 is open.
Transmission of indications.—Although this
system is of the coded duplex type and indica
tions may be transmitted from any station to 50
the control of?ce during the same cycle that con
impulses.
trols are transmitted to the same or some other
The succeeding impulses will now be effective
to govern the control relays of the selected station
only. Upon the picking up of relay 3V1 in re
sponse to the third impulse, relay S01 is main
ating cycle before considering the duplex feature 55
of the system.
station, it is convenient to ?rst explain the trans
mission of indications alone on a separate oper
tained energized throughout the remainder of
There may be trains in various portions of the
the cycle at the station illustrated in Fig. 3 over
a circuit extending from (+), front contact 2l5
territory under the supervision of the operator
of relay S01, front contact 2|2 of relay 3V1 and
winding of relay S0, to (—~).
Transmission of controls-Upon the reception
.of the third impulse (following the third time
space), relay SMR1 is energized for actuating
its polar contact 224 to the right or to the left
depending upon the character of the impulse.
With lever SML in the control office in the posi
tion shown, a (+) impulse is applied to the step
ping line circuit which actuates the contacts of
70 relay F1 to the right for closing an energizing cir
cuit for relay SMR1 which extends from (+),
front contact 215 of relay S01, front contact 2l2
of relay 3V1, contact 2“ of relay F1 in its right
hand dotted position, front contact 2H3 of relay
3V1 and upper winding of relay SMR1, to (—).
and these trains may enter or leave track sections
at two or more points in the territory at sub 60
stantially the same time. Likewise the switches
and signals at the various locations may be oper
ated in such a way by the operator that several
of these tra?ic controlling devices assume new
conditions at substantially the same time. It 65
will thus be evident that when two or more ?eld
stations have new indications to communicate
to the control oflice at the same time, some means
must be provided to permit only one of these
stations to transmit at a time to avoid the trans 70
mission of false indications.
The manner in which ?eld stations are allowed
to transmit only one at a time in a predetermined
order will be explained in connection with the
the lockout feature, this feature being included 75
2,126,211f
in lithe description following _the description of
1'11
relay PLB2 atthe end station, 'winding of relay F2,‘
winding of relay Fl, S line conductor l8,‘back- contact 32 of relay E, winding of relay F,‘ front con
station; assuming that ‘such station is the only tact iii of relay NC and'back contact 25 of relay
It will be
5 :one ‘having new lindicationssito transmit at the .PC to the (—) terminal of battery LB.
noted that the A line conductor extending to ‘the
beginning of , the ‘cycle. 1
Automatic start.,-—Referring to Fig. 3, a change other stations is open atthis time‘ at back-‘contact
in thevconditionrof ‘the detector track section or ' 203 of relay PLA1 and at'front contact 2316 of relay
a change inrcondition of other trainer controlling SA1.
In response to this (—) impulse, relays F1, F‘Pl, 10
10 lzdevices‘at'the‘ station may ‘occur at any time, but
forconv'enience in'describing the operationof SA1 and similar relays at the other stations are
this portion‘of the system it will be assumed that picked up and when relay 'SA1‘ closes ‘its front
relay T1,, (or some other relay whichcontrols the contact 266 and relay SA2 closes its front contact
transmission of indications) shifts its position at the end station, the A and B line conductors
(including all of the stations) are connectedin. 15
15 v‘to effect‘ the deenergization of change‘ relay CH1.
The ‘droppingof relay CH1 closes a circuit for multiple to the S line conductor.
In response to this ?rst impulse, relay VP in
picking up relay ‘PLAl which extends from (+),
back contacts 225rand 226 of relays SA1 and FPI the control of?ce is picked up to close the pre
the operation of the system with respectto the
transmission of indications, from a single ?eld
respectively, back‘contact 221- ofrrelay CH1, back
20 acontacts 228, 229 and 230 of relays W1, 2V1 and
3V1 respectivelyand ‘‘winding of relay PLAl, to
(—).
The-closingpf fronticontact 203 of relay PIAI
establishes aicircuit for energizing the A—-Biline
25 {which extends from the (-\-) terminal of battery
LB‘in the control ‘Of?CG, back contact it of relay
STR, winding ‘ofirelay MB, B'line conductor l3,‘
resistance R1‘, back contact 205 of relay SAI,
lower winding of relay L01, front contact 203 of
30 zirelaypPLAl,~A~,-line conductor l1, winding of relay
MAand'back contact l5 ofzrelay'sTR tothe (-)
terminal'ofg'battery LB. Current flowing over
this-circuit “energizes relays ‘MA and MB in the
control oin'ceandin :‘responseto the energization
35 {of these two relays, relay ‘ILC ‘is picked up by
means‘rofra circuit not shown in detail in Fig l,
butiwhich‘has been shownrin Fig. 5 and extends
through "back COIltEClTETU =of relayjSA‘and front
contacts :60 ,andi?lsof relays MB and MA respec
40 tively to: the winding of relay‘ iCH. With relay
[CH ‘once picked up it 'is' stuck up through a
stick circuit including its stick contact “16' and
back contact '15 -1of. relay LCS; Also with’ relay
lCH energized aigpick-up circuit ‘for relay iLC
,yis
closed=throughfront contact ‘ll of relay ECH,
45
this’ on ‘the assumption that the ‘system is at
rest and-back contact ‘.10 of. relay SA, is closed
and that: noneof thexrelays such'as relay SR are
‘energized.
50
,
'
i, ~ The picking r-uprof: irelayrILC closes ‘an ener~
gizing :circuit for relay'STR at ‘front contact "l2.
Relay‘STR closes aspick-up “circuit for relay NC
which extends from.(+), backcontacts 39, 3B
and r3l=of relays 3V,‘ 2V and IV respectively, ‘front
55 ;contact- 34‘ of relayf-ILC, winding oil-relay NC and
frontcontact "33 of' relay STR, to (—~) .. ' It will
be noted that the switching of contacts M and E5
of irelay-S'I'R: from their backto their front
points deenergizes‘the -A—-B‘line circuit and con
60 inectsv these'two line conductors together.
In response to the picking up of relay NC the
S line conductor is energized witha (—) (condi
tioning) impulse, with‘the ‘return path for the
current extending by way of the A—B line con
jductors in multiple.‘ This circuit extends from
the ,(+) terminalof battery LB,-Yback contact I2
of relay PC, front contact 16 ‘of relay NC, front
contacts VH‘: "and M ‘of: relay STR "through the
windings =of :relays MA and MB, A and B line
70 {conductors I1 and 1‘I9 in multiple, front contact
65
203Jof>relay’PLA1,line (lower) winding of relay
L01, back ‘contact 205' of relay-SA1, resistance R1,
back contact2?4uof relay PLB1, over the B line
conductor throughthe'other stations, to the end
75 :stationhndthence by way of-rbackicontact 334‘ of
viously described ‘circuit for energizing ‘relay E,
which in turn marks the end of the condition
20
ing “on” period by, deenergizing the line circuits.
The system now steps through a cycle as‘before
except in this case relay NC is energized through
out the cycle because of front contacts 42, ‘43 and
it being closed instead of contacts‘48‘, 52,: and 53. 25
This energization of relay NC causes the follow
ing impulses of the cycle to be negative in char
acter.
The above described circuit for energizing the
A—B line conductors for initiating the system
from the ?eld station includes the line winding
of relay LO1 which causes this relay to pick up
and close a stick circuit for its local winding
(after relay SA1 has picked up) extending from
(+), front contact 231 of relay SAT, front con 35
tact 232 and local winding of relay L01, to (—).
Relay L01 establishes the energizing circuit for
relay FPI at its front contact 7202 so ‘that step
ping will be effective at this station during this
cycle.
40
Relay L01 connects (+) by way of its front
contact 233 to bus 235 at this transmitting :?eld
station, so that energy may be extended by
way of the contacts of the relays which are to
control indications, such as relays T1, M1 and the 45
like, for energizing the PLA1 and PLB1 relays
during this cycle in .a manner which will be
later described. Since this is assumed to bev a
cycle for the transmission of indications alone,
it will be understood that none of the SO relays 50
will be picked up, because relay F‘1 (and similar
relays at other stations) actuated its polar con
tact 2! l to the left which is ineffective to estab
lish a pick up circuit for relay S01.
Registration of a field station.-At the particu
lar station having indications to transmit, lock
out relay L01 is picked up and by virtue of its
closed front contact 202 permits the operation of
the stepping relay bank at this station in re—
sponse to the impulses in the S line circuit as 60
repeated by relay FPl. It will be recalled that
relay VP1 is picked up during the conditioning
“on” period and stepping rela‘ys lVl, 2V1 and
3V1 are picked up during the ?rst, second and
third “01f” periods respectively.
When relay FP1 closes its make-before-break
front contact 226 the stick circuit of relay PLA1
is completed to (+) at back contact 225 of relay
SA1. After a comparatively long interval of
time, relay 8A1 is picked up to open back con 70
tact 225 which de-energizes relay PLAl. It will
be understood that the sequential operation of
the MA and MB relays (if such operation takes
place) during the conditioning “on” period .is
ineffective to transmit an indication because the ‘I
12
2,126,211
?rst stepping relay is not picked up until the
time space following this “on” period.
When relay IV1 is picked up during the ?rst
“off” period, indication code transmitting relays
PLA1 and PLB1 are conditioned in accordance
with the particular indication code to be trans
mitted. This conditioning of the PLA1 and PLBl
relays is determined at this step in accordance
with the positions of code jumpers 265 and 266
of Fig. 3.
For example, with code jumper 265 in its full
line position no connection is established between
the (+) terminal of the battery (which is con
nected to bus 234) and the winding of relay PLA1.
With code jumper 266 in its full line position a
connection is established from (+) on bus 234,
code jumper 266, front contact 261 of relay IV1,
back contacts 268 and 269 of relays 2V1 and 3V1
20
respectively and winding of relay PLB1, to (—).
This energization of relay PLB1 is maintained
throughout the ?rst “on” period so that induc
tance BL1 is inserted in the B line conductor
because of open back contact 204.
Since relay PLAl is de~energized, inductance
IO CR AL1 in the A line conductor is short-circuited
by a circuit extending from A line conductor I'I,
back contact 203 of relay PLA1 and front con
tact 206 of relay SA1 to the opposite terminal
of inductance AL1. This effects the compara
30 tively quick energization of the A line conductor
and the comparatively slow energization of the B
line conductor at the beginning of the ?rst “on”
period which results in relay MA and relay F
picking up their contacts before relay MB picks
up its contacts.
With front contact 5I of relay MA closed
before back contact 50 of relay MB is opened
a circuit is established for picking up relay MBP.
With relay MBP picked up during the ?rst “on”
40 period, it is stuck up until relay E picks up to
mark the end of this “on” period over a circuit
extending from (+), back contact 55 of relay E,
front contact 56 and winding of relay MBP, to
(—). Therefore relay MBP will be maintained in
its energized position after relay M'B opens its
back contact 50.
During this “on” period a circuit is established
for energizing relay 2PT which positions its polar
contacts to the right, which circuit extends from
(B+) , front contact I00 of relay MBP, front con
tact IOI of relay MB, back contacts I02 and I03
of relays 3V and 2V respectively, front contact
I04 of relay IV and winding of relay 2PT, to
(CN).
It will be obvious that the above illustrates one
choice of the two indications transmitted during
the ?rst impulse period. The other choice of the
two indications is transmitted when jumpers 265
and 266 are in their dotted line positions. In this
event relay PLA1 is energized over a circuit ex
tending from (+) on bus 234, jumper 265, front
contact 228 of relay IV1, back contacts 229 and
230 of relays 2V1 and 3V1 respectively and Wind
ing of relay PLA1, to (—). Since jumper 266
in its dotted line position is ineffective to com
plete the circuit to relay PLB1, the effect of this
arrangement of the code jumpers is to quickly
energize the B line conductor and to slowly ener
gize the A line conductor. This causes relay MB
to pick up before relay MA and to close a cir
cuit for picking up relay MAP which extends
from (+), front contact 50 of relay MB, back
contact 5| of relay MA and winding of relay
75 MAP, to (—). Relay MAP sticks itself over the
circuit described in connection with the sticking
of relay MBP.
In response to this code combination relay
MAP energizes relay I PT in such a direction that
its contacts are positioned to the right over a
circuit extending from (3+), front contact I 05
of relay MAP, front contact I06 of relay MA,
back contacts I01 and I08 of relays 3V and 2V
respectively, front contact I09 of relay IV and
winding of relay IPT, to (ON). In this instance 10v
relay MBP is not picked up so that (B—) is con
nected to the winding of relay 2PT for position
ing its polar contacts to their left hand dotted
positions.
'
In the previously assumed case (jumpers 265 15
and 266 of Fig. 3 in their full line positions)
relay I PT positions its polar contacts to the left
because the above described circuit to the wind—
ing of relay IPT extends from (B—) at back con
tact I 05 of relay MAP.
20'
With the contacts of relay IPT positioned to
the left and the contacts of relay 2PT positioned
to the right, a circuit is closed for energizing
station relay ST when the second step is taken
and which extends from (+), front contact I I0‘ 25'
of relay 2V, contact III of relay IPT in its left
hand position, contact II2 of relay 2PT in its
right hand position and winding of relay ST,
to (—).
In the above explanation it has been pointed 301
out that relay IPT operates its polar contacts
to the left in response to the quick building up
of current in the A line conductor because relay
MAP remains ole-energized due to the fact that
relay MA picks up before relay MB. Also that
relay IPT operates its polar contacts to the right
in response to a slow building up of current in
the A line conductor because relay MAP picks
up due to relay MB picking up before relay MA.
It has also been pointed out that relay 2PT
positions its polar contacts to the left in response
to the quick building up of current in the B line
conductor because relay MBP remains de-ener
gized due to the fact that relay MB picks up
before relay MA. Also that relay 2PT positions
its polar contacts to the right in response to the
slow building up of current in the B line conduc
tor because relay MBP picks up due to the fact
that relay MA picks up before relay MB.
From the above it will be observed that a
?rst code combination is transmitted by causing
the current to quickly build up in both the A
and B line conductors so that relays MA and MB
are picked up at approximately the, same time
to prevent the picking up of either relay MAP
or MBP, which results in relays IPT and 2PT
positioning their polar contacts to the left.
A second code combination is transmitted by
causing current to quickly build up in line A and
slowly build up in line B for positioning the polar 60
contacts of relay IPT to» the left and the polar
contacts of relay 2PT to the right.
A third combination is transmitted by causing
current to slowly build up in line A and quickly
build up in line B for positioning the polar con 65
tacts of relay IPT to the right and the polar con
tacts of relay 2PT to the left.
A fourth combination is transmitted by caus
ing the current to slowly build up in both the A
and B line conductors so that both relays MAP 70
and MBP will be picked up over a circuit extend
ing from (+), front contact II3 of relay TC,
back contact II 4 of relay F and back contacts 50
and 5| of relays MB and MA respectively to the
windings of relays MBP and MAP respectively.
2,126,211
With‘both relays MBP and MAP picked up the
_ ‘polar contacts of relays IPT and ZPT are posi
tioned to the right.
"
Relay TC‘ is provided to enable the last men
tioned combination to be used, this relay func
tioning to close its front contact H3 in a ?xed
period of time after relay PC closes its front con
“tact ‘30"‘(or relay NC closes its front contact 3|)
for energizing the S line circuit. This time is
adjusted to be approximately the same as the
time it takes‘relay F to pick up with no limiting
inductance in the return line circuit, compris
ing either line A or line B. This adjustment is
is
made by adjusting inductance TL ‘to permit relay
TO to pick up in this ?xed time. The result of
this is that relay TC‘ will pick up in response to
the beginning of an “on” period in‘ its usual
time; but when limiting inductance is included
in both the A and‘ B line conductors, all three
relays F, MA and MB will be comparatively slow
in picking up. Therefore the above described
circuit is‘ completed for both relays MAP and
MBP.
Transmission of indications-After thus hav
ing registered in the control office the particular
?eld station which has indications to transmit,
by picking up relay ST, for example, the remain
ing steps of the cycle are employed for the trans
mission of these indications from the registered
30 station.
‘ For example, with track relay T1 energized as
after the second step is taken so that the A
line is quickly energized for quickly picking up
relay MA. Since relay M1 is de-energized, re
lay PLB1 is picked up over a circuit including
This inserts in
ductance BL1 ‘into the B line circuit which causes
the B. line conductor to be slowly energized so
40 that ‘relay MB will ‘be picked up after relay MA
is picked up for'completing a circuit for pick
ing up relay MBP.
Since relay MAP is not picked up, (B—) is
connected through back contact I05, front con
tact I06‘ of relay MA, back contact .I0'I of relay
3V, front contact I'08 of relay 2V, front contact
II5 of, relay ST and winding of relay IIR, to
(CN). This positions the polar contact of relay
IIR to the right which is ‘effective to de-ener
I03 of relay 2V and front contact I I6 of relay ,
ST ‘for positioning the polar contact of relay 21R
to the right;
It’ will be understood that local circuits may
be‘ controlled by relay HR for indicating the con
dition of' the‘ signals at the station as repeated
by relay‘Mll 'It will likewise be evident that ad
ditional indication storing relays may be pro
vided for‘selection ‘on ‘additional steps of the
cycle for receiving additional indications from
‘the registered station.
‘ During a cycle of operations for the transmis
sion of indications, relay CH1 at the transmit
ting station is restored to its picked up position 15
byf'means of a circuit arrangement which is not
shown so that it is in readiness to register any
other change that may occur at that ?eld sta
tion'.
' End ‘of indication cycle-The step-by-step
operations of the system and the impulsing of
the‘ S line circuit during an indication cycle are
similar torthose operations already explained in
connection with a control cycle.- The S line cir
cuit is opened for acomparatively‘ long time in 25
terval after the last impulse is transmitted in
a manner which has previously been explained in
connection with a control cycle and which is ef
fective to restore the system to normal.‘ The
result of dropping of the relay SAHde-energizes
30.
relay STR and disconnects the channel select
ing circuits from relay NC at the front con
tacts of vrelay ILC.
Lockout‘ between ?eld stations.--As previously
mentioned it‘ ‘may happen that changes occur at
35
a plurality _of ?eld stations at the same time or
in rapid succession so that more than one ?eld
station will havenew indications to transmit at
the beginning of a cycle.
In order to prevent 40
more than one (station actively associating it
self ‘with the communication system during any
particular cycle, lockout means are provided at
section is unoccupied.
each station which are effective to select that
station nearest the control oflice having new in 45
dications to transmit at the beginning of a cycle.
Assuming that a change occurs at the ?eld sta
tion illustrated in Fig. 3, which station is as
sumed to be the one nearest the control office,
the de-energization of change relay CH1 closes
its back contact 221 for effecting the energiza» 50
With relay MBP picked up, (B+) is connected
by way of front contacts I00 and ml of relays
MBP and MB respectively, back contact I02 of
tion of relay PLA1 as previously described so
that the normally de-energized A—B line is en
ergized to start a cycle ofoperations. It has
50 gize lamp OS as an indication that the track
relay 3V, front contact I03 of relay ‘2V and front
contact I16 of relay ST to the winding of relay
previously been mntioned that relay L01 is picked
being slowly energized ‘for picking up relay MAP
as previously described. Relay MAP connects
up when the cycle is initiated from this ?eld sta
tion, and that relays F1, FF1 and SA1 are picked
up in response to the conditioning impulse. The
closure of front contacts HI and 232 of relays SA1
and Lollrespectively, complete the stick circuit 60
for relay LO1 before the pick up circuit includ
ing the-line winding of relay L01 is opened at
‘(B+) by way of its front contact I05 and over‘
back‘contact 205 of relay SA1.
the previously described circuit to the winding of
relay IIR ‘for positioning the polar contact of this
At other stations farther out the line, the pick
ing up of the FP relays opens the pick up circuits 65
of the associated PLA ‘relays at back contacts
similar to back contact 226 of relay FP1, so that
21R. ‘ This positions the polar contact of relay
21R to the left. 1
co
the winding of relay 21R by way of front contact
dropping‘ of ‘ relay ILC in the control office‘ as a
indicated in Fig. 3, relay PLA1 is not picked up
back contact 231‘ of relay M1.
13
‘
Relay T1 will be de-energized when the asso
ciated’ track section is occupied for picking up
relay PLA1 whichresults in the A line conductor
relay to its left hand dotted position which en
ergizes lamp OS as an indication that the asso
ciated track section is occupied.
In the event that relay M1 is picked up when
the second step is taken, then relay PLB1 is de
energized to ‘quickly energize line conductor 13
‘ for picking up relay MB to prevent the energiza
tion ‘of relay MBP. Therefore (B—) through
back“ contact I00‘ of relay MBP is connected to
'
the PLA relays at these other stations are pre
vented from ‘picking up over circuits including
back contacts similar to 22'Iof change relays at
these other stations. Shortly after the picking
up of the FP relays, the SA relays are picked up
so that no other ?eld station can pick up its
PLAj relayduring this cycle because of open back
70
14
2,126,211
contacts on the SA relays similar to back contact
225 of relay SA1.
'
In other words, the last chance that a change
at a ?eld station has for actively associating it
self with the communication system ends when
the FP relay at such a station is picked up.
This means that the PLA relay (with suitable
exponent) of a transmitting station must be en
ergized for a sufficient period of time prior to
.10 the picking up of the contacts of the SA relay
to allow the line winding of'the associated LO
relay to be energized over the A_—B line circuit
for picking up its contacts so that it may be
stuck up after the picking up of the SA relay.
15 It will be assumed that relay CH1 at the ?rst
?eld station is de-energized and shortly after the
closure of its back contact 221 the corresponding
relay at the second station also becomes de-en
ergized. Relay PLA1 at the ?rst station is picked
up and shortly thereafter the PLA relay at the
second station is picked up. Upon the closure of
front contact 2ll3of relay PLA1 at the ?rst sta
tion the A—B line circuit is energized to pick
up relays MA and MB in the control o?ice for
initiating the cycle in the manner previously de
scribed.
‘
It will be recalled that the closure of front
contacts 60 and BI of relays MB and MA re
spectively effects the energization of relay ILC
picking up relay STR to initiate the cycle.
.39 for
Relay NC is now energized so that a (—) im
pulse is applied to the S line circuit, the return
path being by way of the A andB line con
ductors in multiple. Since the line windings of
feeCl the lockout relays are included in the A line con
' ductor and since the A line conductor is open
from the ?rst station outward (at back contact
293 of relay PLAl), the lockout relays at the
other stations‘ (beyond the ?rst station) cannot
get energy through their line windings, which
results in these lockout relays becoming de-en
ergized before the SA relays pick up to close the
64.9
above described stick circuits.
7
At the ?rst, station however, the energization
of the S. line in .the control of?ce causes relays
F1, FP1 and SA1 to pick up in sequence for com
pleting the above described stick circuit for relay
LO1 before its pick up circuit is de-energized.
The picking up of relay SA1 at the ?rst station
and the picking up of the SA relays at the other
*‘ stations (including relay SA2 shown in the dotted
rectangle in the upper right hand portion of Fig.
3) completes the continuity of the A line
conductor.
At the second station which is assumed to have
‘ its CH relay dropped and its PLA relay picked
its geographic location.
Irrespective of whether
such changes occur sequentially as above as
sumed or whether they occur simultaneously, the
station nearest the control o?ice will obtain en
ergy through a front contact similar to 203 of
relay PLA1 for energizing its lockout relay so that
at the end of the conditioning period relay LO1
will be stuck up and remain up for the remain
der of the cycle, while at the station farther out
the line the lockout relay is not picked up and the
PLA relay is dropped to remove the associated
inductance from the A line circuit at this station.
Although the lookout feature has been ex
plained with reference to‘ the ?rst station having
preference over the second station it will be
understood that similar conditions may exist be
tween various combinations of stations in the
system. It is believed, however, that the above .20
explanation is sufficient for an understanding of
all such combinations, remembering that in each
case the station nearest the control o?ice which
picks up its PLA relay before the picking up of
the ET relays, has preference over other stations. 25
Two way transmission.—1t has been pointed
out that control and indication cycles may each
occur separately or simultaneously. The opera
tions for control and indication cycles alone have
been described and it will now be pointed out 30
how the system functions when controls and in
dications are transmitted during the same cycle.
An actuation of the starting button in the con
trol o?ice through the medium of relay SR re
sults in the picking up of the CD relay during
the time that the system is at rest and during
any time up to the end of the period marked off
by the picking up of relay SA in the control office.
This circuit for relay CD is shown in Fig. 5 of
the present disclosure and is also disclosed in the 4,0
above mentioned application Ser. No. ‘711,383.
In other words, if a ?eld station has initiated the
system which results in the picking up of relays
ILC, STR, NC,v F, FP and SA, all as described in
connection with an indication cycle, the control 45
of?ce may pick up a CD relay during this period ‘
and before relay SA is picked up because the
pick up circuits of the CD relays extend through
back contacts of relay SA.
After relay SA ispicked up due to a ?eld sta
tion initiating a cycle, then the control office
must wait until the next condition of rest of the
system (relay SA de-energized) before it can pick
up a CD relay for the transmission of controls.
In this connection it will be understood that
relay ILC‘ cannot be picked up when the storing “
up,,the F, FP and SA relays are also energized
relay SR which is actuated in response to the
because the S line circuit through this station
is complete. At the second station the picking
up of the SA relay drops the associated PLA
operation of a starting button STB is in its ener
‘ relay because of open back contact similar to
225 and since the line winding of the lockout
relay at this stationpwas not energized, the lock
out relay remains down during this cycle. It will
be understood that relay PLA1 at the ?rst sta
tion is also'dropped when relay SA1 opens its
back contact 225 so that relay PLAl may be con
7,5,
that a change was recorded at the second station,
but the ?rst ?eld station is superior by reason of
ditioned upon the succeeding steps‘ of the cycle
for conditioning the A line circuit to form this
portion of the indication code. The dropping of
relay PLA1 at the ?rst station does not drop the
associated lockout relay because of its previously
described stick circuit.
In brief, the ?rst ?eld station recorded a
change in condition prior to, or at the same time
gized position because energy is supplied to the
winding of relay ILC through a back contact 13 60
of the storing relay (see Fig. 5).
Recalling that a ?eld station can energize its
lockout relay any time up to the picking up of its
associated SA relay, it will be seen that a ?eld
station may be in condition to transmit its indi 65
cations during the same cycle that the control
o?ice transmits controls because relay CD can be
picked up during the initiating period of a cycle
initiated from a ?eld station. In this connection
it will be noted that when the ?eld station in
itiates the cycle in advance of a control o?ice
start, resulting in relay ILC being picked up and
stuck up over a circuit including a front contact
T0 of relay SA (see Fig. 5), then no CD relay can
be picked up because their pick up circuits in- 7.5M
2,126,211
clude this back contact 70 on relay SA as pre
viously mentioned. This is necessary because
when relay ILC is stuck up for a particular cycle
it causes a phantom code comprising a series of
(~) impulses to be transmitted.
‘ With relay CD picked up and a ?eld station
having its lockout relay picked up atthe start of
a‘particular cycle, the ?rst impulse of the cycle is
(+) determined as previously described. This
110
("+) impulselpicks up all of the SO relays and
determines‘ that stepping at all stations will be
started. The character of the impulses applied
to‘ theS line, as determined by the particular CD
relay which is picked up, selects the required
station by dropping out the SO relays at the sta
tions not to be selected in the manner previously
described. Since the lockout relay at a particu
lar station is assumed to be picked up, stepping
will continue at this station in the event that it
20 is not the selected station for controls because of
the closure of a front contact such as front con
tact 202 of the lookout relay.
The resulting cycle ‘of operations is thus the
same, insofar as the transmission of impulses over
“ the S line for the selection of a station iscon
cerned, ‘ as was previously described in connection
with ‘a control cycle alone. Similarly the result
ing operations of the cycle, insofar as the condi
tioning of the A and B line conductors is con
cerned, is the same as‘descri'bed for a cycle dur
ing which indications alone were transmitted. It
is believed that the above brief explanation is suf
?cient to clearly indicate that, since the trans
mission of controlsand the transmission of in
dications are effected by the separate and dis
tinct ‘conditioning of the-line circuits, these trans
missionsmay be combined and brought about dur
ing a single cycle of operations.
“ Description of‘modi?cation.—'1‘he modi?cation
do shown in abbreviated form in. Fig. 4 indicates a
second method for detecting’ (in the control office)
the time lag in the building up of current in the A
and‘ B'lines due to the inclusion of the inductance
units ‘such as AL,1 and IBL.1 in these line conductors.
In this modification the pilot relays (correspond
ing to relays IPT and ZPT of Fig. 2B) are neutral
typerelays instead of the magnetic stick type.
These relays are deenergized at the beginning of
acycle when relay SA is picked up and their stick
circuits are prepared when relay lV picks up.
These pilot relays IPT and 2PT are energized
by the inductive impulses in the secondary wind
ings of transformers, the primaries‘ of which are
included in the A and B line circuits. These sec
=ondary transformer windings include recti?ers
in the circuits leading to the ‘channel‘selecting
arrangement through ‘which therpilot relays are
selected, so thatthese relays'may be picked up
or, not as determined by the indication trans;
mitted from‘ the ?eld station.
‘ ‘
Local primary windings of the transformers are
included ‘in a local circuit in the control office
connected across the stepping line and the A~—B
lines. This local circuit is designed to contain re—
65 sistance andv inductance of values corresponding
to theresistance and inductance of the line cir. cults, so that when the inductance units such‘ as
AL1 and’BL1 at a transmitting station are short
circuited, current will build up in these local pri
‘ mary windings at the same rate (or at a slightly
lesser rate)‘ ‘than in the primary windings includ
ed‘in the line circuits.‘
When inductance unit ALl, for example, is in~
eluded-‘in lineA, current through the local primary
winding of the transformer associated with this
15
line builds up quicker than the current through
the line primary winding of this transformer,
thus producing a magnetic ?ux for causing an
induced current to flow in the secondary winding
of this transformer in series with the recti?er for
energizing relay IPT.’ The recti?er is employed
so that an exact balance between the line primary
winding and the local winding of the transformer
is not necessary, it being assumed that the surge
of current produced in the secondary winding of
this transformer will be of suflicient intensity
and duration to energize a quick acting neutral
type relay.
To describe the operation of the modi?cation
disclosed in Fig. 4 somewhat more in detail it will
be assumed that the ?eld station illustrated in Fig.
3 initiates the system into a cycle of operations by
energizing the A—-B line conductors for picking
up relays MA and MB in the control office as pre
viously described. In this connection it will be
apparent that the MA and MB relays are for
purpose of initiating the system from a transmit
ting ?eld station and are not used for receiving
indications. It will further be assumed that the
?eld station illustrated in Fig. 3 transmits its
indications in the manner previously described
. and it will be explained how the circuit modifica
tion of Fig. 4 functions to receive these indications.
With this explanation of the manner in which
pilot relays IPT and 2PT are distinctively con 30
ditioned, it will be obvious how the indication re
ceiving relays associated with the station which
is registered in the oihce are likewise conditioned
on the next step of the cycle as selected by the
second stepping relay. It is therefore believed 35
unnecessary to include the indication receiving
relays in the Fig‘. 4 disclosure, since their opera
tion may be understood from the pilot relay op
eration.
When relay E closes its back contact 32 to mark 40
the beginning of the ?rst “on” period, an energiz~
ing circuit is completed from one side of the line
battery, back contact 32 of relay E‘, balancing
resistance RS, local primary windings LPB and ‘
LPA of the transformers in series and front con
tact l5 of relay STR to the other side of the line
45
battery. The constants of the circuit including
these local primary windings and resistance RB
are such that current builds up through these
windings at the same (or at a slightly lesser) rate
that current builds up in line primary windings
PB and PA of these transformers when induct
ance units AL1 and BL1 of the transmitting sta
tion are short-circuited.
Since the transmission of this indication as
sumes relay PLB picked up (as previously de
scribed), inductance BL1 is included in the B line
conductor but inductance AL1 is short-circuited
out of the A line conductor. This means that
current will build up through line primary wind
ing PA and local primary winding LPA at ap
proximately the same rate and since these wind
ings are oppositely wound the effect on second“
55
60
ary winding SAT is neutralized so that no cur
rent is induced in this secondary winding. There
fore no current flows through recti?er RA to
pilot relay lPT which results in this relay re
maining deenergized.
Current builds up in the 13 line conductor at a
slower rate than in the A lineconductor so that 70
the current builds up through‘ the line primary
winding PB at a substantially lower rate than it
builds up through the local primary winding LPB.
Therefore these currents are not neutralized be
cause the current through winding LPB reaches
75
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