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Патент USA US2135548

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Nov. 8, 1938.
J. E. WILLING
2,135,548
' TRACK CIRCUIT FOR RAILROADS
Filed June 14, 1934
h, ATTORNEY
2,135,548
Patented Nov. 8, 1938
UNITED STATES PATENT OFFICE
2,135,548
TRACK CIRCUIT FOR RAILROADS
Joseph E. Willing, Rochester, N. Y... assignor to
General Railway Signal Company, Rochester,
N. Y.
Application June 14, 1934, Serial No. 730,646
5
15
30
40
12 Claims. (Cl. 246-41)
This invention relates in general to track cir
track shunt due to track ballast and a rapid
cuits such asused in railway signalling practice change in track shunt due to’ train occupancy.
and has more particular reference to means for
Further objects, purposes and characteristic
increasing the e?iciency ofshunting and dis
features of the invention will appear as the de
criminating between a shunt provided by a train scription, progresses, reference being made to the
in the track section and a shunt due to ballast
accompanying drawing which shows by way of
conditions.
example one ' form that the invention may
In railway operation it is quite essential that assume.
the track relay connected across the track section
The single ?gure diagrammatically illustrates
at one end of a signalling block be su?iciently
one form of the present invention applied to a
energized. when the block is unoccupied to pick single stretch of track.
up and hold up with certainty. It is likewise
Apparatus-A section of railway track includ
essential that the occupancy of the track section ing rails I is shown separated from the adjacent
willeffectively shunt the relay so that it will be track sections by insulated joints 2. A track
positively released. For examplain the usual battery B and a limiting resistance D are shown
track circuit if the normal holding current is connected to the track rails at the right hand end
too high, shunting may not be effective to drop of the illustrated track section. The primary
the relay and if the normal holding current is
winding of a transformer TR is included in
so lowthat shunting will bemore positive, then series with the circuit extending from the lower
it is possible that at times the holding current track rail‘ to the track battery, the secondary of
may be insu?icient to hold the relay in its picked this transformer being connected to a relay G
up 7 position when the track section is not
which is for the purpose of including and exclud
occupied.-'
ing resistance Hfrom the track circuit for lock
Taking the above into consideration. it will be ingv relay A, as will be later described.
seenthat the usual variation in ballast resistance
Relay A is normally energized and when it
encountered in practice, due primarily to changes drops to close its normally open back contact,
in weather’conditions, ~may operate to interfere resistance 0 is removed from the track circuit.
with the proper operationiof the track relay un
The limiting resistor D is adjustable in order to
less some means is‘ provided for discriminating regulate the current ?ow from battery B to the
between changesdue to ballast leakage and track track rails for the most efficient operation.
occupancy.
Track relay T is shown connected across the
As the ballast resistance increases, the leak
track rails at the left end of the illustrated track
age current between the rails decreases so that
section. As typical of the control exercised by
the voltage across the terminals of ‘ the‘ track
the track relay, a semaphore signal SG is illus
relayconnected to the track circuit increases. trated and it will be understood that any suitable
Conversely as the ballast resistance decreases, type of signal may be used, of which SG is merely
ballast leakage» increases and the terminal volt
a typical example.
age'at the relay terminals decreases. Unless proNormal conditi0ns.—With the circuit in its
vision is‘ made for regulating» the current ?ow normal condition as illustrated in the ?gure,
through the relay this current will vary over a track relay T is normally picked up over a circuit
considerable’ range and'possibly cover a range at’
times which-will prevent proper response of the
relay- under occupied and unoccupied conditions
Mi
of the track section.‘
,
It-is'proposed in- accordance with this invention
to providemeans- associated with the circuit of
a track section for detecting changes due to track
occupancy’ and unoccupancy and changes due to
leakage currents caused by variation in ballast
resistance-between the rails of the track. In
accordance with the present invention it is also
proposed toimproverthe shunting ei?ciency of the
track circuitand for thispurpose a discriminat
ing arrangement is included in the track circuit
55;
which~>discriminates between aslow change in’
5
1O
25
30,
35'
extending from the (+) terminal of battery B,
primary winding of transformer TR, lower track
rail, winding of relay T, upper track rail, resist~
ances D and C in series to the (—) terminal of
battery B. The current ?ow in this circuit main 45
tains relay T in its picked up condition. A cir
cuit in‘shunt of relay T and the primary winding
of transformer TR includes the winding of relay
A and resistance H in series.
Under normal or
dry ballast conditions current through this shunt
circuit is effective to maintain relay A in its
picked up position. This circuit may be traced
from the (+) terminal of battery B, resistance
H, winding of relay A, resistances D and CV in
series to the (-) terminal of battery B.
2
2,135,548
Ballast changes-A decrease in resistance be
tween the rails of the track due to the ballast
conditions changing (by increasing the shunt
path between these rails) tends to reduce the cur
rent flow through the shunt path including relay
A because of the increased potential drop across
the circuit including the primary winding of
transformer TR and relay T, which drop reduces
the potential drop across the'circuit including
relay A and resistance H.
tain the circuit in condition for greatest train
shunting efficiency.
.
'
Itwill also be noted that relay G, transformer
TR. and resistance l-I provide the lockout of re
lay A on instantaneous shunt and that these ele—. '
merits remove the lookout of relay A on quick re
moval of the shunt, thus making the locking out
and the removal of the locking out functions re
sponsive to train shunt but not responsive to
changes in ballast resistance caused by Weather 10
Consequently when the leakage current due .to . conditions. It will be understood that the lock
‘out of relay A due to track occupancy is the re-.
an impaired ballast condition increases'to a pre
determined value, relay A is suf?ciently shunted
to drop its armature. The closure of back contact
15 3 of relay A short circuits resistance C which re
moves this resistance from the circuit leading to
the track rails so that more current flows through
the track rails and relay T in series. The effect
is, therefore, to increase the current ?ow through
relay T when the ballast shunt reaches a value
which causes relay A to drop. As ballast condi
moval of resistance H by the operation of relay G
to give relay A morecurrent so that it will re
main in its picked up position.
Under the worst ballast conditions, when relay -
A has dropped its’ contact 3 and removed resistor
C from the ‘circuit, then the entrance of a train
into the track section causes relay G to operate
contact 4 to its left hand dotted position which re
moves resistorll from the circuit including the
winding of relay A.- This increases the shunt
tions improve, a point will be reached where the
ballast resistance is increased to such a value that across track relay T as before which assists in
dropping this relay but under this condition relay
the effective shunting effect of relay A is dimin
25 ished to the point which will allow relay A to pick 7 A remains down because it is effectively shunted 25'
up and again insert resistance C in the track cir
cuit for placing the circuits in the conditions
illustrated in the ?gure.
signal' circuits of signal vSG or for any other pur
‘ Track oceupancy.-Assuming that ballast con
pose required by the usual practice in connection
30 ditions are such that relay A is picked up, the
entrance of a train into the illustrated track
section causes a sudden increase of current
through the primary winding of transformer TR
due to the sudden shunting of relay T.
This sud
by the'train.
‘
'
Contact 5 of relay T may be used to control the
with track relay circuits.
'
Summary-With the track-conditions normal '
(high resistance shunt due to a dry track), the
track relay T is maintained energized as long as
the track is unoccupied by means of current flow
35 den rush of current through the primary wind
ing of the transformer sets up a potential across
ing from battery B through resistors C and D and
the primary winding of the transformer. in series.
the secondary winding, including the winding of
'When a train enters the track under this condi-,
the mag-stick polar relay G, in such a direction
tion. the low resistance shunt placed across the‘
that relay G operates its polar contact 4 to the _ track rails causes an increase of current ‘?ow
It will be understood that although this in
duced current in the secondary winding of the
transformer is only momentary it is of sufficient
through resistors C and D and the primary wind
ing of transformer TR. Due 'to the shunting
duration to operate the contact of relay G.
Contactr4 actuated to its left hand dotted posi
vtakes place in track relay T, regulator relay Aand
40 left.
45 tion short, circuits resistance H which decreases
the resistance of the shunt path across the track
circuit by removing this resistance. This de
crease in the shunt resistance has the effect of
increasing the sensitivity of relay T to the train
50
shunt.
}
'
When'the train leaves the illustrated track sec
tion, the sudden removal ‘of the shunt across track
relay T causes 'a sudden decrease in current
through the primary winding of transformer TR
which induces a potential in its secondary wind
ing opposite to that previously described, which is
eifective to operate contact 4 of relay G to" the
right. This removes the short circuit from re
sistor H which places the circuits in the condition
60 shown in the drawing.
'
Since relay G is of the polar type and since it is
energized by an impulse of current quickly gen
erated in the secondary winding of the trans
former,
it will be understood that the response of'
65
its ‘contact 4 is substantially faster than the re.
sponseof contact 5 of relay T, both when the track
section becomes occupied and when'it becomes
unoccupied.
I
'
‘
.
40"
effect of the train a reduction in current flow
resistor
H;
'
‘
r
'
'
y
a
This sudden increase in current through the
primary of the transformer operates contact 4 of
relay G to the left which removes resistor H from
the circuit‘ by short circuiting it. This causes a
further increase in current flow through resistors
C and D and a" further reduction in current flow 50
through relay T (because of the increased shunt
conductance) ‘as well as an increase in current
?ow'through the winding of relay A. All of this
is eifective to accomplish the release of relay T.
Whenthe train leaves the track section under
this condition the current ?ow through resistances
C and D is suddenly reduced which is accom
panied by a sudden reduction of current’ flow '
through the primary of transformer‘TR as well
7 as an increase in current ?ow through the wind
ing of relay A and through the winding of relay
'T.
This
sudden reduction
in
current
607'
flow
through the‘ transformer winding is effective to
operate contact 4 of relay G to the right which
inserts resistance H in the circuit for further re
ducing the current ?ow through resistances C and
D and the winding of relay A, while the current
flow through relay T is further increased'
When the rails of the track are slowly shunted
From the above description it will be noted
that relay A acts as a potential relay which cuts
out resistance C when track ballast resistance is
low and cuts resistance C back in the circuit when
the ballast resistance increases to a predeter
due to the ballast ‘conductance changing in re 70
sponse to wet weather conditions, the current
through resistances C and D and the primary
mined cut-over point, which is effective to main?
flow through relays T and A and resistorH‘ until 755:
windingof transformer TB is slowly increased.
This condition effects a reduction in ' current
2,1 85,648
a point is reached where'relay A drops its-back
contact to» shortcircuit resistance C. This re-'
What I claim is:1. An automatic voltage regulator for a track
moves resistance C from: the circuit, effecting a
circuit comprising; a source of current connect
ed'to the rails of a track; a resistor in the con-.
nection/between said source and said rails; a
slight sudden increase in current through resis
tor Dandv the primary winding of transformer
TR" aswell as through thewindings of relays T
and A ‘and the resistor H.- This'slight increase
in» current is not sufficient to cause the opera
tion of relay G.
10
When a train enters the track section under
this condition, a'sudden and large increase of’
current ?ow takes place through resistor D and
theprimary- winding of transformer TR While a
reduction in current flow takes- place through
15 the winding of relays T and A and resistor H.
This; sudden increase in current through the
transformer operates contact 4 of’ relay G to
the left which short circuits resistor H and re
moves-it from the circuit, thereby causing a fur
20 ther increase in current flow vthrough relay A
as well as a reduction in current ?ow through
the primary winding of transformer TR and the
winding of relay T.‘
When the train leaves the track section, a
25 reduction'in current ?ow takes place through
resistor D and the primary winding of trans
._ former TR as well as an increase in current flow
through the windings'of relays A and T. This
sudden reduction in current flow through the
30 transformer winding operates contact 4 of relay
G- to the right/which inserts resistance H in the
circuit for further reducing the current flow
through resistor D and relay A and for increas
ing the current ?ow through the primary wind
35 ing of transformer TR and the winding of track
relay T.
When the track is occupied, an increase in the
shunt across the rails due to a wet track condition has the effect of applying an additional
5:0 shunt to track relay T and since this relay is
already shunted‘ down by the train this condition
has no noticeablee?ect. Relay A will not drop
under this condition because resistance H is
shunted out and when the train leaves the track
section resistance H is cut into the circuit which
may or may not drop relay A, both of which ap
plies more current to track relay T for causing
it to pick up.
The drying out of the track ballast during
50 track occupancy has no effect on relays T or A
because relay T is effectively shunted by the
train and since this shunt is not noticeably
changed by the drying out of the ballast, relay
A does not change its position. When the train
leaves the track section under this condition re
sistance H is 'cut into circuit which supplies re
lay A with more current so that it will receive
su?icient current to pick up if the track has
60
3
dried out to the cut-over point.
It will be clear from the above description that
this invention provides means whereby there is
a positive discrimination between the track cir
cuit conditions due to track occupancy and due
to ballast leakage and that changes in ballast
65 leakage condition the circuits for more ef?cient
track relay connected across the rails of said
track; a second relay connected in shunt of said
track circuit; said second relay being adapted to
effectively exclude said resistor from said con
nection when the voltage of said track circuit 10,
falls below a predetermined value and to effec
tively include said resistor in said connection
when the voltage of the track circuit increases
above a predetermined value; and auxiliary
means for effectively including a second resistor 15
in and excluding it from said shunt.
2. An automatic voltage regulator for a track
circuit comprising; a source of current connect
ed to the rails of a track; a resistor in the con
nection between said source and said rails; a
.20
track relay connected across the rails of said
track; a second relay connected in shunt of said
track circuit, said second relay being adapted
to effectively exclude said resistor from said con
nection when the voltage of said track circuit 25
falls below a predetermined value and to- effec
tively include said resistor in said connection
when the voltage of the track circuit increases
above a predetermined value; and auxiliary
means for effectively including a second resistor 30
in and excluding it from said shunt, said aux
iliary means responding only to a rapid change
of current flow in said track circuit caused by
the sudden application or removal of a vehicle
shunt.
3. An automatic voltage regulator for track
circuits, comprising, in combination with the
track circuit and a source of current supply for
said track circuit having an adjustable resistance
in series therein, a second resistance connected
in series with said adjustable resistance and the
source of current supply, contact points electri
cally connected between the two resistances and
the‘ current supply, a relay and a third resistance
in series included in multiple with said resistances
and said source, means controlled by said relay
for causing said contact points to effectively in
clude and exclude said second resistance from
said circuit, said relay being responsive to the
slow increase and the slow decrease of the shunt
resistance across said track circuit to control said
contacts. and means responsive to the quick ap
plication and the quick removal of a shunt across
said track circuit for effectively excluding and
including said third resistance whereby the oper
ating and release voltage values of the circuit of
said relay are varied.
4. In combination, a section of railway track,
35
45
50
55
a source of current connected across the rails of
said section, a ?rst relay receiving energy from 60
the rails of said section and responsive to the
steady value of current with which it is supplied,
a second relay, means also receiving energy from
the rails of said section for energizing said second
relay when the value of the current received by 65
shunting of the track relay by the train.
said means is changed due to the entrance of a
The above rather speci?c description of one
form of the present invention has been given
solely by way of illustration and is not intended
train into said section, said means being incapable
of responding to the steady value of such current,
and means controlled by said second relay for de
70
creasing the energization of said ?rst relay.
5. A track circuit for a section of railway track
70 in any manner whatsoever in a limiting sense.
It will be obvious that the general principles
herein disclosed may be embodied in many other
. organizationswidely di?erent from that illus
trated without departing from the spirit of the
75 invention as de?ned in the following claims.
including a source of unidirectional current; a
transformer having its primary winding included
directly in said track circuit; a polarity responsive
device included directly in series in the secondary 75
4
2,135,548
winding of said transformer; a track relay ener
' 9-. In combination, a section of railway track, a
gized to an extent. depending upon the value of
current ?owing .in said track circuit; and means
including a contact of said polarity responsive
source of current connected across the railsrof
device actuated, in response toga sudden increase
into said section, and means including a contact 5
in the current in the vprimary winding of said‘
transformer, to a‘ position to decrease the degree
controlled by said device for shunting the rails of
said section when artrain enters the section. '
of energization of said track relay; whereby said
track relay'is also controlled in accordance with
a source of current connected across the rails of
the rate of change in a particular direction of cur
10 rent ?ow in said track circuit.
6. VA track circuit for railroads comprising, a
section of railway track, a source of unidirectional
current connected across the track rails at one
' end of said section, a track relayreceiving energy
15 from the track ‘rails at the other end of said sec
tion, a transformer having its primary winding
nected across the other end of said track; electro
magnetic regulating means connected to the track
current in the track circuit caused by the en
trance of a train into said section for decreasing
the current through said track relay to release its
.
said section, a track relay receiving energy from 10
said rails, a device receiving energy from said
source and responsive to the entry of 'a train in
said section, and a shunting path ‘for the rails of
said section controlled by‘said device. ,
11. In a track circuit; in combination with an 15
insulated stretch of track; a source of current
connected acrossone end and a track relay con
relay energized only by-current induced in the
secondary winding of said transformer, and oper
‘
10. In combination, a section of, railway track,
included in said track circuit; and an auxiliary
20 ated in response to the relatively quick change of
25
said sections, a relay, receiving energy from said
rails, a device responsive to the entry of a train
armature.
_
7. A track circuit for railroads comprising, a
uni-directional source of current and a track re
lay in series, a transformerhaving itsprimary
winding included in, said track circuit, and an
auxiliary relay energized only by current induced
in the secondary winding of said transformer and
causing operation of a contact to a particular
position only when current in one direction is in
duced in said secondary winding by the relatively ‘
. quick change in the current in said track circuit
35 caused by the entrance of a train upon said track
circuit, said contact when operated to said par
ticular position acting to decrease the current
through said track relay to release its armature.
8. In combination, a section of railway track,
a source of current connected across the rails of
said section, signaling apparatus receiving energy
from the rails of said section, a device responsive
to the entry of a train into said section, and a
shunting path for the rails of said section con
'45 trolled by said device.
rails at said one end for automatically increasing
the current supplied to said track when the, volt- ,
age across saidone end due to slow variations in
the inter-rail resistance falls below a particular
value; and impulse actuated means responsive to.
a rapid decreasev in said inter-rail resistance for 25
causing a decrease in the current supplied to said 1
track below that existing immediately after such
rapid decrease in inter-rail resistance occurred,
said impulse actuated means comprising a polar
relay operatedgto one position in response to a 30
rapid increase ininter-rail resistance and to an
other position in=response to a rapid decrease in
inter-rail resistance.
7
'
v
'
12. In a track circuit, a track relay, track rails,
a‘ regulator relay arranged to automatically in 35
crease the energizing current through said track
rails and track relay when the potential across
the track rails adjacent said regulator relay due
to ‘weather conditions on’ said track circuit falls
below a particular value, and an impulse actuated
locking means inductively coupled with said track
circuit so as to be distinctively responsive to the
shunting of said trackrrails by a train for when
assuming ‘one condition preventing a change in
position of said regulator relay.
'
V
JOSEPH E. WILLING.
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