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Патент USA US2135499

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Nov. 8, 1938.
o. s. FIELD
2,135,499
RAILWAY TRACK CIRCUIT
Filed June 21, 1935
ATTORNEY
2,135,499
Patented Nov. 8, 1938
‘
STATES PATENT. OFFICE
RAILWAY TRACK CIRCUIT
Oscar S. Field, Rochester; N'. Y., assignor to
General Railway Signal Company, Rochester,
NY.
A Application June 21, 1935," Serial No. 27,737
13 Claims.
(Cl. 246-41)
‘ This invention relates in general to railway
signallingtrack circuits, and more particularly
to. improvements. intrack circuit voltage regulat
ingmeansg
eti
‘
,
j A normally energized track circuit includes a
track relay energized su?iciently when the asso
ciated track section is unoccupied to attract its
varmature by current flowing from a track bat
“ terythrough the track rails in series, but when
a train" shuntj is applied to the track rails, the
increase .in'current at the battery end of the
circuit flowing through the included resistance
must reduce the voltage at the relay end suffi
‘ciently torelease thetra‘ck relay armature. The
ballast between the rails of the track section
however varies considerably in resistance accord
ing ‘to weather conditions, thereby forming an
interrail'shuntwhich may vary the interrail volt
age sufficiently to at times prevent proper track
circuit, operation. In other words, when the
track circuit current is adjusted to provide proper
operation under any one condition of the track
ballast,‘ a'decrease in ballast resistance may de
crease the interrail voltage sufficiently to prevent
25 the attraction of the track relay, armature upon
the removal of a train ‘shunt, or an increase in
ballast resistance may increase the interrail volt
age su?icientlyto producea dangerous condition
30
by preventing the release of the‘armature when
the train shuntis applied.
a‘ 7
It then becomes desirable to employ a means
for maintaining ‘a constant interrail voltage
when thetrack section is unoccupied regardless
of f ballast resistance , changes, but to allow
changes in interrail voltage caused by the appli
cation or removal of a train shunt. In my prior
applicationnse'r. No.’ 25,472 ?led June '7, 1935, I
have provided such a regulating me'anscompris
ing a motor means for actuating a variable re
sistorin ‘series with the track battery, which
motor means is controlled by a relay connected
across the track rails, the control relay being .
more sensitive than the track relay thereby re
sponding to interrail voltage changes which occur
45 in increments or decrements too small to op
erate' the track relay, and being caused by
changes in ballast resistance which occur slowly,
these increments or decrements are compensated
for before they can cumulatively amount to a
change suiiiciently to cause operation of the track
relay. The application of a train shunt in this
arrangement causes a reduction in interrail volt
age which abruptly amounts to a much greater
change than is permitted to occur in response
55 to ballast resistance changes, and consequently
the motor driven‘ variable resistor does not start
to compensate for this abrupt decrease in volt
age before the armature of the control relay has
been operatedrb‘eyond its position taken in re
sponse to decrements in ballast resistance, and
the armature of the control relay in this ex
treme position is ‘arranged to prevent operation
of the _motor driven variable resistor while a
train shunt exists across the track rails.
The increased reliability of detecting a train 10'
shunt provided by, the above regulating means
however is dependent upon the proper operation
of certain apparatus employed. In other words,
theoperation of the motor driven variable re
sistor to prevent an increase in ballast resist
ance, from increasing the interrail voltage to a
value preventing reliable release of the track
relay armature ‘is dependent upon the proper
response of thelcontrol relay to this increased
voltage, which response may be prevented by
an open Winding, loose connection or the like.
Likewise, the, compensation for an increase in
interrail voltage caused by an increase in ballast
resistance even when properly detected by the
control relay is dependent on the proper opera
tion of the motordriven variable resistor which
operation may be prevented by a failure of the
motor windings, mechanical driving means or
the like. Consequently, it will be clear that when
a track circuit regulating means is relied upon
to provide proper track circuit operation by auto
matically changing the characteristics of a track
circuit in response to ballast resistance changes,
a failure of the apparatus employed in this regu
lating means may under certain conditions result 35
in an unsafe condition.
This application is an improvement upon the
invention disclosed in my prior application Ser.
No. 25,472 ?led June 7,1935, and no claim is
made in this application to subject matter shown
and claimed in said prior application.
' In view of the ‘above and other considerations,
, it is proposed in accordance with the present
invention 'to' provide‘ an improved means for
maintaining a constant voltage between the rails
of a track section when unoccupied by a train
regardless of changes in interrail ballast resist
ance, and for allowing changes in interrail volt
age caused by the application or removal of a
train shunt. It is further proposed to provide 50
means in such a track-circuit voltage regulat
ing means operating in response to the failure
of any of the apparatusemployed to effect regu
lation to provide and to retain a condition in
the track circuit which results in restricted but 55
2
2,135,499
safe train operation until the cause of such fail
ure has been corrected.
Other objects, purposes and characteristic fea
tures of the present invention will be apparent
as the description thereof progresses, during
which reference will be made to the single ?gure
16 is provided on one leg of the, magnetic core
of relay C which is connected in series with a
winding [1 on one leg of the magnetic core of re
lay K, and windings l6 and I‘! thus arranged in
series are connected across the track rails l as
shown. A second winding I8 is provided around
of drawing which shows in a diagrammatic and
the other leg of the core of relay C and con
conventional manner the present invention ap
nected in series with a second winding l3 wound
around'the other leg of thecore of relay K, and .
plied to a typical form of a railway track circuit.
In the accompanying drawing, a section of
track rails I is shown as electrically insulated
likewise windings l8 and I!) are connected across
the track rails I. The windings I 6 and I8 are
from the adjacent track by insulating joints 12/ "s01 arranged on the core of relay C that‘ the in-,
to form a conventional insulated track’ section.~ A terrail potential causes current to ?ow there
center-tapped track battery B is connected'acros's
15 the right hand end of this track section, that is,
the extreme (+) terminal of battery B is con
nected through a variable resistor R to the right
through which produces cumulative ?ux values
which normally provide an upward tractive 15'
force on a pivoted armature 20 associated there
with, but the windings Hand [9 on relay K are
hand end of the lower track rail (I, while the so arranged that vthis same current normally pro~
extreme (—) terminal is connected through a‘ duces opposing ?ux values in the core thus pro
20 manually variable resistor 3, such as usually
ducing substantially no tractive force on a simi
employed in track circuits, to. the right hand end
lar, pivoted armature 22 associatedtherewith,
of the upper rail 1. A primary+secondary track
relay combination such asshown in my. prior ap
A lower compression spring 24 isj'arranged to
exert'an upward biasing force on armature 20
plication Ser. No.‘ 711,397, ‘filed Feb. ,15, 1934,
which is adjusted by a screw 25 to substantially
25 is shown associated with the left hand end I of
oppose the normal gravitational bias on arma-‘
this track section, this arrangement being illus
trated as a means forprovidlng improved track
circuit operation although it" is =under'stoodthat
a single track relay .mayof course'be employed
30
in the usual manner."
‘
r
'
In this primary-secondary relay combination,
the magnetomotive" force required to attract the
armature of a primary track relay PTfrom its re
leased position issupplied by the normal track
35 circuit current ?owing through all of its wind
ings, but after thearmature of relay PT has been
25
ture 20, and an upper spring 26 is also provided
to exert a downward biasing force on armature
20 which is adjustable by a screw 21‘ toequally
oppose a predetermined upward magnetic at
traction of the armature 20. The track circuit 30
is adjusted by positioning the manually variable’ ‘
resistor 3 so that an interrail voltage exists when
the track section is unoccupied which is found
to provide reliable track circuit operation, and
this interrail voltage provides a de?nite upward 35
attracted, a secondary relay'ST (which ‘controls
attraction of the armature 20 of the control re
lay C, which upward attraction obviously has a ,
signal circuits and the like by contacts such as
l) is picked up through a front contact 4, there
energization of the track relay combination at
40 by substituting a substantially equivalent re
sistor 5 for a portion of the winding of relay PT
by a make-before-break contact 6, thus reducing
the magnetomotive force'o'ifrelayv PT to a value
just su?icient to reliably retain its armature in
45 an' attracted position. '.In this manner,v a track
relay combination may be arranged to drop away
at nearly the same interrailvolta'ge that is suf
?cient to cause its picking up, and consequently
it will be clear that when the interrail voltage
50 of the track section is maintained at a'valueper
mitting proper picking up of the combination, a
rather slight reduction in interrailvoltage can
cause its release in response to a, train shunt.
A means for operating the variable resistor R
55 at the right hand end of the track, section has
herein been illustrated as a conventional perma
nent magnet direct current motor including an
armature A‘ and a'permanent magnet III, or of
course any other suitable motor means could be
60 employed, such, as a series or shunt ?eld direct
current motor, the permanent magnet ?eld- being
considered preferably inview- of saving, the en
ergy required to magnetize an ‘electro-magnetic
?eld.
The armature A of , this'motor' is illus
substantially constant relation to the degree of
the other end of the track section. ‘
The downward biasing force of, spring 26 is
then adjusted by screw 21 so that the upward
magnetic attraction of armature 20 produced by
this ‘normal interrail voltage is balanced by the
biasing. force of spring 26 so that amovable con
45
tact 28 attached to the armature 20 by an insu
lating block 29 is positioned midway between a
pivoted front contact 30 and a pivoted back con
tact..3l. The pivoted contactsv 30 and 3| are each
biased inwardly ‘by compression springs 32 and
50
33 respectively to contact with inner ?xed con
tacts 34 and 35 respectively, this contacting force
being adjustable by screws 36 for varyingthe
biasing‘ force of springs 32 and 33. A movable
contact ?nger 39 is attached to the armature 22 55
of relay K by insulating connectingy'meansllo,
and the armature 22, being normally released as
previoulydescribed, engages the movable con
tactj39 with a back ?xed contact 4|.
' In describing .the op'erationof the present in
vention, it will ?rst be considered that the resist
ance of the ballast between therails l increases
s'othat the interrail leakage current decreases.
This decreases the current ?owing through resist
65 trated as connected through a suitable reduction
gearing means comprising a worm. gear H at
ances>3 and R and slightly reduces the voltage
tached to the shaft of armature A and driving
terrail voltage of: the track circuit and likewise
the energization of windings l6 and I8 of relay
a sector gear l2 attached to theshaft of an arm
I43 arranged to contact in a suitable manner with
70 various portions of the resistance-wire R.
A means for controlling the energization and
the direction of current'in the armature A is
40
drop therethrough which obviously raises the in
C. ' The relay C is adjusted to respond to a much
smaller change in interrail voltage than can pos
sibly causeoperation of the primary-secondary
track relay combination; and consequently this
provided by a control relay C, and a check relay gradual decrease in interrail leakage current soon
K is also provided to check the continuity of causes a su?icient increase in interrail voltage to
75 the windings of the control‘relay C. A winding upset the rather delicate balance on the armature
65
2,135,499
20' and operate ‘the movable contact 28'into en
gagement with the’ pivoted front contact 30. The
biasing, forcei on‘the pivoted ‘contact 30 exerted
by spring? 32 however is adjusted so that the en
gagement of the movable contact 28 therewith
caused by this slight increase in interrail voltage -
does not havesu?icient force to disengage front
contact‘30 from the fixed? contact 34.
‘
A circuit is now completed for applying one
polarityfof energization to the armature A which
maybe (traced from the‘ (+) or extreme right
hand terminal of battery B, through the pivoted
front contact 30 engaged by the movable contact
28',‘ and upwardly through armature A to the cen
15 ter terminal of battery B. This upward direction
of current through armature A is in a‘ proper
direction to cause rotation of the resistor arm I4
in a clockwise direction which shunts out a small
er portion of the resistance wire R through a cir
20 cuit including the movable contact 39 of relay K
engaging the ?xed back contact 4| and the ?xed
restore thenormally adjusted interrail voltage,
thereby restoring the balance of the forces acting
on armature 20 of-the control relay C and again
positioning the movable contact 28 midway be
tween the front and back contacts 30 and 3|.
This operation of the control relay C and the
motor driven variable resistor also continues in~
termittently as long as the ballast resistance con
tinues to decrease, thereby maintaining the inter
rail voltage substantially constant except for the
small changes necessary to cause release of the
armature 20 of the control relay,vwhich as de
scribed is much smaller than can possibly cause
the release of the track relay means.
It is of course understood that a regulating 15
means of the present type should not operate
when a 'train is occupying the associated track
section, as such operation might compensate for
the reduction in interrail voltage effected by the
train shunt and prevent the release of the track
relay, thereby defeating the purpose of the track
back‘ contact 34 engaged by the pivoted front
circuit. In thepresent arrangement, the entrance
contact 30' of relay C. In this manner, the resist
ance in series with the track battery to the track
rails is increased by one direction of operation of
the armature A, which continues until the inter
rail voltage has been reduced to its normally ad
of a train into the associated track section shunts
the track rails I to cause an abnormal increase in
justed value, thereby restoring the energization of
the control relay C to a value which balances the
30 forces on armature 20 and positions the movable
contact 278 midway between ‘the front and back
contacts 30 and'3l.
35
3
'
'
~ "The above operation of the control relay C and
the motor driven variable resistor obviously con
tinues in an intermittent manner as long as the
ballast resistance continues? to increase, ‘thereby
maintaining a substantially constant interrail
voltage,-the only change in the interrail voltage
beingthat which 'is required to cause an unbal
40 ance of theiforces on armature 20, which as pre
viously described is'much smaller than the change
required‘ to cause operation of the track relay
means;
‘
-
Now considering that the resistance of the com
45 paratively dry ballast decreases, it will be clear
that an increased ballast leakage current occurs
which ?ows'through the increased resistance in
serted into the track circuit by the variable resis~
tor R. 3A slight reduction in the interrail poten
50 tial thenv occurs which reduces the energization of
windings I6 and I8 of relay C to again upset the
rather delicate balance of forces acting on arma
ture 29 and in this case cause the movable con
tact 28 to engage the pivoted back contact 3|.
Likewise, the movable contact 28 does not engage
‘the pivoted back contact 3I with sufficient force
to overcome the biasing. force of spring 33 so that
the pivoted back contact 3| is not disengaged
from the ?xed contact 35. This completes a cir
cuit for applying a different polarity of energiza
tion to armature A which may be traced from the
center tap of battery B, downwardly through ar
mature .A, through movable contact 28 of relay C
engaging the pivoted back contact 3|, and
65 through ?xed contact 35 to the (—) or extreme
left hand terminal of battery B. y‘
In this‘ case, current flows downwardly through‘
armature'A thereby causing a reverse direction of
rotation which moves" the variable resistor arm I 4
in a counter-clockwise direction to shunt out a
greater portion of the resistance wire R.
This
‘rotation of the armature A continues until the
variable ‘resistor arm I4 is moved in a counter
clockwise direction to‘a position which decreases
75 the resistance of the track circuit su??ciently to
the current ?owing through resistances R and 3, 25
thereby providing an abnormal voltage drop
which reduces the energization of windings I6
and I8 of the control relay C to a much greater
degree than the rather slight reduction in ener
gization permitted by the regulator in response to 30
an increase in ballast leakage current.
This greater degree of reduction in the ener
gization of windings I6 and I8 caused by the
train shunt greatly reduces the normal magnetic
attraction of armature 20, thus allowing the 35
force of spring 26 to exert a downward force
on the pivoted back contact 3I through the
movable contact 28 which overcomes the force
of spring 33 and disengages the pivoted back
contact 3| from the ?xed contact 35.
The en
40
er'gizing circuit for armature A is thus opened at
contacts 3I—-35 which prevents operation of the
motor driven variable‘resistor to restore the nor
mal interrail voltage, and consequently the ar
mature 20 of relay C remains in its extreme 45
lower position and the interrail voltage remains
at a reduced value which releases the track re
lay combination as long as the train shunt exists
on the track section.
The present system then differentiates be 50
tween a reduction in interrail voltage due to in
creased ballast leakage current from a reduction
due to a train shunt in a manner to prevent the
operation of the motor driven variable resistor as
long as the train shunt exists on the track cir 55
cuit. In other words, the application of a train
shunt causes a reduction in interrail voltage
which abruptly amounts to a much greater
change than is permitted to occur in response
to ballast'resistance changes, and consequently 60
the motor driven variable resistor does not start
to'compensate for this abrupt decrease in volt
age before the armature of the control relay C
has been operated downwardly with a force suf
?cient to disengage contact 3| from contact 35 65
and prevent energization of the armature A.
It will now be clear that when the apparatus
of the present system thus far described is op
erating properly, a constant voltage is main
tained between the rails of the track section 70
whenunoccupied by a train regardless of changes
in interrail ballast’ resistance, but a reduction in
interrail voltage is permitted which occurs ab
ruptly such as caused by the application of a
train shunt. The present system also maintains 75
2,135,499
.the interrail voltage at the proper adjusted value
regardless of gradual changes in the terminal
voltage of the track battery B such as may be
caused by improper charging, abnormal loads or
the like. In other words, the adjustment of the
biasing forcesof springs 24 and 26 on the arma
ture 20 provides a de?nite standard unaffected
by variable conditions of the track circuit, to
' which standard the interrail voltage or the en
-10 ergizationof .vvindings l6 and I8 is related, there
by permitting any gradual change in interrail
voltage regardless of vits cause to effect opera
tionof the regulating means. It‘ is further ob
vious that this ‘de?nite standard to which the
interrail voltage is related also determines a ?xed
point at which the action of the regulating means
is ‘stopped, thereby preventing the “hunting” or
overrunning operation which is inherent to some
regulator-operation.
.
'
>
'
t
" In the present system, any change in interrail
voltage results in a corresponding change in cur
rent in windings l1 and I 9 of the check relay
K,.but such current changes do not affect the
normal released position of armature 22. In
25 other words, the windings I‘! and I9 being in
parallel circuits will receive equal‘current values,
and being oppositely arranged will produce neu
tralizing flux values regardless of the interrail
voltage as long as these parallel circuits which
30 include windings .l6 and I8 of relay C are in
tact.
However, considering now that either winding
IE or winding I8 of relay C becomes open cir
cuited, such as by a broken wire or loose con
35 nection, thereby reducing the flux value in the
control relay C to such an extent that the arma
ture 2B is released in the same manner as dur
ing the application of a train shunt, that is, the
movable contact 28 is operated downwardly and
40 may be operated with suflicient force to disen
gage contact M from contact 35. Under this
condition, either winding l8 or l6 alone could
notiproperly detect a change in ballast resist
ance in a manner to cause operation of the mo
45 tor driven variable resistor and compensate
therefor. Consequently, a continued increase in
ballast resistance might cumulatively amount to
an increase in interrail voltage which would'be
suf?cient to prevent reliable detection'of a train
50, shunt by the track relay'combination.
~In~the present'arrangement, however, the fail
ure-of‘ either winding IE or l8 of the control
relay C at the same time de-energizes ‘the asso
ciated winding‘ I‘! or 19 of the check relay K
so that the flux produced by the Winding remain
ing energized is no longer opposed by the ?ux
of the other winding, thereby picking up arma
ture 22 of relay K. The picking up'of arma
ture 22 opens the circuit shunting out a portion
60 of the resistance wire Rjby disengaging the mov
able contact 39 from the ?xed back contact 4|,
thereby inserting the total value of resistance
B into the track'circuit which reduces the track
circuit current to a value precluding the possi
65 bility of a failure of the track relay combination
to respond to-a train shunt.
'
. I
normally‘: increasing, the ‘interrail. voltage. ~ In
otherwords, the check relay K prevents any dan
gerous condition from obtaining in the track cir
cuit due to a, failure ,ofyeither- winding I6 or
winding l8 of the controlrelay C by causing’ the
insertion of a maximumvresistance value which
may result in a_.condition~r>providing more re
stricted train: movements, but which obviates the
possibility of afailure’of the-track relay combi
nation tov detect the presence of ‘a train in a track
section. In this connectionit should be'noted
that the windings [Be-l1; and l8—|9‘ are indi
vidually connectedto the track circuit lead-in
Wires, so that a single break cannot open both
pairs of windings unless the break occurs in the 15
track
circuit itself.
> I,
>
-
g
'
'
a
g
It may now be seen that although the arma
ture of- relay K is attractedin'response to the
de-energization of one or the other of the wind
ings l6 and I8 of relay C, it will not be ‘at 20
tracted, in response to the’ de-energization of
both windings. The two windings l6 and I8
however~havei~ no portion of their energizing
circuits'in common which is not a part. of the
track circuit, and consequently it is very re-,»
mote that both ofthese windings could become
de-energized simultaneously and leave the track
circuit intact. However, if one of ‘the windings
of relayC fails‘ andpicks up relay K, it may
be advisable to mechanically retain the armature
22 in its picked up position in order to guard
against its subsequent release by the‘ failure of
the remaining winding of relay C before the‘ de
fective one hasbeen replaced.
'
-
.
A manually'releasable latch 44 may be pro
vided for this purposeiwhich is biased by a spring
45 to retain the armature 22 in an attracted
position thereby holding contacts 39,-“ open.‘
In usingthis vlatch arrangement in the ‘present
system, it, is assumedthat-incaseiof a failure 40
of a windingof relayC, the ‘track relay com
bination will either,be“ immediately released or
will not pick up upon the departure of'a train
from the track section,_and consequently, at
tentionvwill be called to. thefact that an abnor
mal condition exists at this track section, there
by allowing vthe defective circuit to bev corrected
andv the system restored to itsproper operating
condition by manually releasing the latch 44.
A meanscis also provided in the present sys
tem for preventinga dangerous condition from
erly reduce theinterrail voltage. in; response to I
a decrease in ballast leakage current or the like.
For example, considering that-an‘ increase in
the interrail voltage occurs, due for example to
an increase in ballast resistance, the armature
20 of the control relay C is moved upwardly into
engagement with ‘the pivoted front contact '30 60
thereby normally operating'the motor driven re
sistance to -a position compensating for this
voltage .increase, but however, if the variable
resistor does not respond forsome reasons such
as a failure of a. motor Winding or the like, the 65
increase in interrail voltage might cumulatively
It will likewise be clear that in the event- the
failure of either winding "5 or l8 of the con
amount to a value which would prevent proper
trol relay C does not result in‘the disengage
However, before the interrail voltage has
reachedgsuch a value, the armature 20 of the
control relay C is attracted upwardly, with suffi
ment of the pivoted back contact 3| from the
?xed contact 35 to prevent operation of the ar
mature A, a dangerous condition would result
from the following operation of the motor driven
variable resistor to decrease the resistance in
sertedinto the track circuitfthereby also ab
50
obtaining in thetrack circuit due to a'failure
of the'motorl drivenvariable resistance to prop
tracrk circuit operation.
,
cient force to overcome the force of spring .32
and disengage the pivoted front contact 30'from
the ?xed contact 34, thereby. opening the circuit
shunting out a portion of the resistance wire R.
5
2,135,499
In: this manner, the total value of resistance R
is inserted into the track circuit in the same
in voltage before the armature of the control re
manner as during the attraction of armature
22 of the check relay K, thus resulting in an
response to a decrease in ballast resistance.
‘ abnormally low interrail voltage which may pro
lay has been operated beyond its position taken in
The
control relay in this position is arranged to open
the control circuit for the motor driven variable
resistor, thereby preventing compensation for the
reduction in interrail voltage caused by the train
vide a restricted traf?c condition by releasing
the track relay combination, but which prevents
an abnormally high interrail voltage from ob
shunt, and of course the armature remains in this
10, taining which would. prevent the detection of a ' position until the train departs from the track
train shunt.
I
section to restore the system to its normal condi
.
It is also considered expedient to provide a
means for mechanically retaining this circuit
open at contacts 30-—-34 when a failure of the
motor driven variable resistor occurs, as other
15 wise a subsequent train shunt would reduce the
tion.
10
.
. The control relay in the present system is also
provided with a check contact means which is
operated and mechanically retained in response
to the occurrence of an abnormally high interrail 15
energization of the control relay 0 to a degree ‘ voltage, and in the present system, this contact is
allowing contact 30 to again engage contact 34, arranged to remove a shunt around a portion of
thereby defeating the purpose of this check con
tact arrangement. Consequently, a similar man
ually releasable latch 48 has been provided which
is biased by a spring 49 to retain the pivoted
front contact 30 inits upper position, thereby
mechanically holding contacts 30-34 open.
Likewise it is considered that this abnormally
25 low track circuit current will either immediately
release the track relay combination or prevent
its picking up when the track section becomes
unoccupied,‘thereby calling attention to the fact
that an abnormal. condition exists and allowing
the cause of the failure of the motor driven
variable resistorto be corrected and the system
restored to normal by the manual release of the
latch 48.
,
~
A track circuit regulating means has thus been
‘provided wherein a simple and e?icient perma
nent magnet motor means has been employed
the variable resistor, but obviously a separate re
sistor could be provided in the track circuit for
this purpose. In other words, a check means is 20
provided which responds to an excessive interrail
voltage such as may be caused by a failure of the
motor driven variable resistor to properly increase
the track circuit resistance, and this check means
is arranged to prevent an unsafe track circuit 25
condition by inserting an increased resistance
value.
-
‘
vThe check relay is provided to likewise prevent
an unsafe track circuit condition from arising due
to a failure of a winding of the control relay, that 30
is this check relay as previously mentioned does
not normally attract its armature, but in the
event one of the windings of the control relay
fails or becomes open, the armature of the check
relay is attracted and mechanically retained 35
which also removes a shunt around a portion of
to operate a variable resistor included in the ‘ the variable resistor, but likewise a separate re
- track circuit, the operation of this motor being
normally governed by a control relay which is
40 provided with two windings, each winding being
energized by separate parallel circuits connected
across the rails of , the track section and each
circuit including a winding of a check relay.
A change in current in the windings of the con
sistor could also be provided in the track circuit
for this purpose. The check relay thereby pre
vents an abnormally high interrail voltage from
being applied to the track circuit either by un
warranted operation of the motor operated vari
able resistor caused by the reduced magnetism of
the control relay or by an increased ballast re
.trol relay causes a corresponding operation of
sistance which cannot be detected by the im
the control relay armature while the windings
paired sensitivity of the control relay.
of the check relay are so arranged that a change
in current does not affect the check relay arma
ture as long as both the windings of the control
and check relays are intact.
In this manner, the control relay which is more
The above rather speci?c description of one
form of the present invention is given solely by
the way of example, and is not intended, in any
sensitive than the track relay is able to detect
changes in interrail voltage which are too small
to cause operation of the track relay, and the con
trol relay is arranged to accordingly cause opera
tion of the motor driven variable resistor to com
pensate for these small changes in interrail
voltage. Inasmuch as changes in interrail volt
age caused by ballast resistance changes occur
slowly, the motor, driven variable resistor is able
to compensate for the ballast resistance changes
in increments or decrements of interrail voltage
detected by the control relay before they can
cumulatively amount to a change su?‘icient to I
a?ect the track relay.
,
I
The present system thereby maintains a sub
stantially constant interrail voltage while the
track section is unoccupied regardless of ballast
resistance changes, but upon'the entrance of a
70 train into the track section, a reduction in inter
rail voltage occurs which abruptly amounts to a
much greater change than is permitted to occur
in response to ballast resistance changes, and con—'
sequently the motor driven variable resistor does
not start to compensate for this abrupt decrease
manner whatsoever, in a limiting sense.
415
It is to 50
be understood that various modi?cations, adapta
tions and alterations may be applied to meet the
requirements of practice without in vany manner
departing from the spirit or scope of the present
invention except as limited by the appended 55
claims.
What I claim is:—
1. In a track circuit, an insulated track section,
a source of energy for the track section, a re
sistor in series with the source of energy to the 60
track section, a motor driven arm contacting with
various portions of the resistor, a control relay
having two windings connected in multiple across
the track section, a check relay having two oppos
ing windings one in series with one of the wind
65
ings of the control relay and the other in series
with the other winding of said control relay, said
check relay acting to attract its armature when—
ever its two windings are not equally energized, a
circuit connecting the motor driven arm to one 70
extreme end of the resistor through a back con-.
tact'of the check relay and a contact on the con
trol relay, said contact being opened only in re
sponse to current in the windings of the control
relay above a predetermined value, contacts on 75
2,135,499:
6V
thecontrol relay forcontrolling operation of'the. aiicontrolrelay' responsive to~theitrack circuit
motor driven arm in accordance with relatively
' relay preventing operation of the motor driven‘
voltage, a variable resistance in series with the
source supplying voltage across the track rails
of‘ the track circuit and operated to different
positionsbyrth‘e control relay to maintain a sub
arm in responseto current in the windings of,
the control relay below a predetermined value.
stantially constant voltage acrosslthe track rails,
contact means on the control relay operated in
slight changes in current in the windings: of the
control relay, and contact means on the control
2. In a track circuit including a track relay
response to an excessive, track circuit voltage,
energized by current flowing from a track battery
a‘ manually releasablelatch means'for holdingv
the contact means in its operated position, and
resistor in series with the track circuit, a power
operated arm contacting with various portions‘ of
the resistor, a control relay having two windings‘
connected in multiple across the track section and,
governing operation of the power operatedarm in
accordance with relatively slight changes in inter
rail voltage, a check relay responsive to the
integrity of the windings of said .control' relay,
and a shunt circuit connecting the power-oper
means controlled by said contact means for in
cluding all of said variable resistance intthe track
10" through the' rails of a track section in series, a
20v ated arm with one end of the resistor through a
contact ofthe checkwrelay and a: contact of the
control ‘relay operated by an‘excessiverinterrail
voltage.
,
1
3. In'a track circuit,
insulated track sec
255 tion, a source of, energy fOI'IthGQtI‘aCK circuit, a
power operated variable resistor in the track cir
cuit, a control relay having windings energized
in accordance with the interrail potentialof the
track circuit and, governing operation of the
3,01 power operated variable resistor, a, check relay
responsive to, the‘ integrity of the control relay
windings, means controlled: by thezcheck relay
for increasing the resistance of the track" circuit
upona failure of the windings of thecontrol
35 relay, and means controlled by thecontrol relay
for increasing the resistance of'the track circuit
upon an excessive interrail potential.
4. In a track circuit: includinga track relay;
means energized by currentlfrom, ajtrack bat-,
tery ?owing through? therails of a track section
in series, a power-actuated variable: resistor in
the track circuit," a control‘ relay controlling the
actuation of the variable resistor-‘in accordance:
with an increase or a decrease, in interrail'ivoltage‘
45 between predetermined limitsof variation, means
on the control relay forlpreventin'g actuation" of’
the variable resistor iniresp‘onse to;a1decrease in
interrail potential, beyond saidzpredetermined"
limits of variation, andmeans .onith'e controli
50 relay for causin'g'a. maximum resistance, to be
inserted into thev track circuit in responseto an
increase in interrail potential beyond's'aid pre-'
determined limits of variation.
5.. Ina track circuitfvoltage regulating means,
5.5 a‘, control relay having an energizing circuit-re
sponsive to the track circuit voltage, a power,
operated regulator means controlled by the con
~
circuit, a power-operated regulator governed by‘
sai'dcontrol relayi soi asito maintain aisubstan
tially constant‘ inter-rail voltage upon vgradual
changes in the resistance of the-track; circuit, a‘
check @relay included in series with said control
relay in such a manner astoYbe actuated upon
a' break in the energizing vcircuit/30f said control:
relay and rendered e?ectiveupon such actuation
for inserting apredetermined resistance insai'd‘
track- circuit, and ‘meansvincludi'ng, a contact of
' ' 251'
said control relay which‘is actuated upon the? '
presence of an excessive voltage across the track‘
circuit‘ for causing said predetermined resistance
torbe inserted in said track circuit, whereby the
failure ofveithe‘r‘said control relay'ci'rcuit or‘ an»
excessive voltage across the track circuit ‘results
301
in" the insertion of a predetermined“resistance in
said track circuit.
~
’
'
9; In» a‘ track'circuit forrailroads, an insulated
track ‘section having > afsource" of energy cone
nected across the rails at one end of the section
and a tracklrelay connected acrossthe rails'ate
the‘ other end of‘v the ‘section; a’ power-operated 40'.
variable- resistor included in" series with, the
source of energy at‘th’e' end-of said track section
at'which said source is located,la<control relay’
having'windings energized-in accordance with
the interirail potential of the’ track» circuit and
effective to govern the‘ power-operation of said
variable resistor so as to; maintain a substan
tially constant inter-rail potential‘ upon gradual
changes in the ballast resistance of the track
circuit, and a check relay‘ arranged to attract itsv 5,0:
armature upon a failure of the- energizing circuit
fo'rr‘th‘e control relay, ‘said check‘ relay being ef-"
fective upon the" attraction of’its armature for
inserting a predeterminedresistance in the track
circuit;
'
55:
1'0'.>I'n a track eircuitfor railroads in 'combin'a?
tionwith an insulated section of track and'a
source of' energy for supplying currentto the
appliedto said track circuit, and means respon
track at one end ‘of the section foren'ergiz'ing a
track relay connected to the track at the oppo 60;
control relay for reducing the voltageapplied to
said track circuit independently of said regulator.
6. In a track circuit voltage regulatingv means,
a control relay responsive to the track circuit
65 voltage, a variable resistor in series, with. the
source supplying: voltage to thetrackcircuit con
trolled by the control relay, a ‘check relay ar
ranged to attract itsarmature upon a ‘failure’ of
the energizing circuitior the. control relay, said’
check relay upon attraction of its armature: in
serting the maximum resistance of said resistor
inythe track circuit, and-a manually releasable
latch means for holding thearmature of-the
check relay in its attracted‘position.
75
7
8. In atrack circuit voltage regulating means, 155
a control relay having an energizing ci'rcuit‘ree
sponsive to the. inter-rail voltage of the track:
trol relay for gradually regulating the voltage
60 sive to a break in the energizing circuit of said
70
circuit feed independently of the'voperated posi-v
tion. of said variable resistance;
,
'7. In a track circuit voltage regulating means,
site end of said section, a‘ variable resistor in
series with said source ofenergy, electrically op
erable ‘means for actuating said resistor to vary‘
7 its resistance, a control relay having windings ' '
connected across the track rail'sand-having‘an
armature cooperating with the windings‘ of-said
relay, s'pringmeans for biasing‘ said armature
away from its-attracted position, a frontcontact
closed when the’ windings are energized above a
predetermined value, an operating circuit for said
electrically operable means closed by said front
contact for- actuating’ said variable resistor to in
crease the resistance insaid'track circuit and '
reducethe potentialiacross the ‘windings of said'
control relay so as to returntheir energization,
2,135,499
7
to said predetermined value, another contact op
erated by excessive current in said control relay
by the shunting of the track circuit by a train
for preventing operation of said power means,
such as would occur if the variable resistor fails
and other contact means responsive to a rela
tively quick and large movement of said arma
ture as may be caused by the failure of said
to insert added resistance in the track circuit,
said another contact when operated under such
conditions causing a predetermined resistance to
be inserted in said track circuit independently of
power operating means to insert added resist
ances in said track circuit for permanently pre
said electrically operable means for actuating
venting operation of said power operating means
said variable resistor.
11. In a track circuit for railroads having the
usual track‘relay connected across the rails of an
until such other contact means is manually re
stored.
10
13. In a track circuit for railroads having the
usual track relay and source of current, a var
iable resistor connected in series with the source
of current at the end of the track circuit at
which said source is located, power-operated 15
means for actuating said variable resistor and
having an operating circuit for increasing its re
sistance and another operating circuit for de
insulated track section at one end and having a
source of current connected across the track rails
at the other end of such section, a power-operated
variable resistor included in series with said
source of energy connected to the track rails,
control means responsive to gradual changes in
the inter-rail‘ voltage for governing the power
operation of the variable resistor to increase or
20 decrease the resistance in the track circuit to ob~
tain a substantially uniform inter-rail voltage
creasing its. resistance for regulating the voltage
impressed across the track rails, a control relay 20
having its windings responsive to the voltage ap
with varying ballast leakage conditions, and
plied to the track rails and having an armature
means operated upon the energization of said
control means by an excessive inter-rail voltage
25 such as may exist in the event that the power
as to assume an intermediate neutral position
erated condition until manually restored.
when its windings are energized with a prede 25
termined value of current, two front contacts on
said control relay one of which is opened by a
small movement of said armature fromv a neutral
position and the other of which is opened by a
relatively larger movement of said armature 30
from a neutral position with said one front con
12. In a track circuit for railroads having the
usual track relay and source of current connected
power operating means to cause an increase in
operated resistor fails to respond to said control
means, for including a predetermined resistance
in series with said source of energy independent
ly of the existing condition of said variable re
30 sistor, said means being maintained in its op
across the track rails of an insulated track sec
tion, a variable resistor in series“ with said source
of current at the end of the track circuit at
which said source is located, power operating
means for actuating said resistor to increase or
decrease its resistance, a control relay responsive
to variations in the inter-rail voltage of said
track circuit and having a movable armature,
spring means for biasing said armature towards
its retracted position with such force that such
armature assumes a neutral position for a pre
45 determined inter-rail voltage, means rendered
effective upon the movement of said armature
from its neutral position by an increase or de
crease in inter-rail voltage above or below said
predetermined inter-rail voltage for governing
50
biased to a retracted position with such a force
the operation of said power operating means to
cause either an increase or a decrease in the re
sistance of said resistor as the case may be until
said armature is restored to its neutral position,
contact means responsive to a relatively quick
and large movement of said armature as caused
55
tact governing the operating circuit for said
the resistance of said resistor and said other
front contact eifective when operated for pre 35
venting the operation of said power operating
means, and two back contacts on said control
relay one of which is closed by a small movement
of said armature towards its retracted position
and the other of which is opened by a relatively 40
larger movement of said armature towards a re
tracted position with said one back contact gov:
erning the operating circuit of said power-op
erated means to cause a decrease in the resist
ance of said resistor and the other back contact 45
eifective when operated to prevent the opera
tion of said power-operated means, ‘whereby
gradual changes in the inter-rail potential are
governed by the operation of said variable re
sistor to maintain the inter-rail potential sub
50
stantially constant, and whereby relatively sud
den and large changes in inter-rail potential are
effective to prevent the operation of said vari
able resistor from its last operated position.
OSCAR S. FIELD.
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