US1194116A - Railway signaling - Google Patents

Description

H. D. ABERNETHY.

RAILWAY SiGNALiNG.

APPLICATION FILED JUNE 24, 1915.

l 1 94, 1 1 6 v Patented Aug. 8, 1916.

4 SHEETS-SHEET I.

OPERA 7:50 B Y S/G/VA L 6 9 H. D. ABERNETHY. RAILWAY SIGNALING.

APPLICATION FILED JUNE 24. I915.

1 1 94:, 1. 1 6 Patented Aug. 8, 1916.

4 SHEETS-SHEET 2.

OPERATED BY SIGNAL 6 {L INVENTOR H. D. ABERNETHY.

RAILWAY SIGNALING.

APPLICATION man JUNE 24.1915.

Patented Au". 8, 1916.

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H. D. ABERNETHY.

RAlLWAY'SIGNALING.

' APPLICATION FILED JUNE 24. 1915. 1,194,1 16. Patented Aug. 8,1916.

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slaMaL 5' INVENTOR O ERATED 5v S/GNA 1. 8 5

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'. tion or HARRY D. ABERNETHY, OF CLEVELAND, OHIO.

RAILWAY SIGNALING.

Application filed June 24, 1915.

To all whom it may concern:

Be it known that I, HARRY D. ABERNETHY, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Railway Signaling, of which the following is a specification. I

My invention relates to railway signaling, and more particularly to signaling for single track stretches over which trains move in both directions, such for example as stretches of single track between passing sidings.

I will describe two forms of railway signaling systems embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figures 1 and 1 when placed together end to end, constitute a diagrammatic View showing one form of railway signaling system embodying my invention. The left hand end of Fig. 1 should be placed adjacent to the right hand end of Fig. 1. Figs. 2 and 2 when placed together end to end constitute a view similar to Figs. 1 and 1 but showingamodification of the system shown therein. The left hand end of Fig. 2 should be placed adjacent to the right hand end of Fig. 2.

Similar reference characters refer to similar parts in each of the views.

Referring first to Figs. 1 and 1 I have here shown a stretch of single track AB between two passing sidings C and D, and also a portion of the next adjacent single track stretch extending to the left from the siding C. Traffic through the stretch A-B from east to west is governed by signals S S and S located at intervals through the stretch, and traflic through the stretch in the opposite direction is similarly governed by signals S S and S located at intervals through the stretch. Signals S and S guard the entrances to siding C, and signal S similarly guards one entrance to siding D, while signals S and S are located in the stretch extending to the west of siding C and correspond to signals S and S in stretch AB. Each signal is adapted to give three indications, viz., stop, caution and clear; as here shown each signal is of the semaphore type capable of three positions, viz., stop or horizontal, cauand clear or Each Specification of Letters Patent.

Patented Aug. 8, 1916.

Serial No. 36,070.

signal is controlled by a caution indication circuit and a clear indication circuit as will hereinafter appear.

The stretch AB is divided by insulated joints 3 into several successive sections AE, E F, and F-B, and as here shown a pair of opposing signals is located near the junction of each two adjacent sections, but I do not wish to limit myself to this particular location of the signals. The sections AE, etc., are provided with track circuits including track relays for control of the signals; as here shown each section is provided with but one such circuit, comprising the rails of the section, a track battery 6 connected with the rails near one end of the section, and a track relay connected with the rails near the other end of the section and designated by the letter T with an exponent corresponding to that of the adjacent signal governing traffic through the section.

Signals S and S are the end signals or the absolute signals governing tratlic into the stretch A-B from sidings D and C respectively, whereas signals S S, S and S are intermediate signals provided for the purpose of properly spacing trains moving in the same direction through the stretch. Signal S is controlled by two relays R and 7 the former being a difierential relay comprising two coils 1 and 2'. The 45 or caution indication circuit for signal S is from battery 4 through wire 5, front contact 6 of relay R wires 7 and 8, controlling mechanism of signal S wire 9, contact 10 of re lay R wires 16 and 11 to battery 41; it will be seen that this circuit can be closed only when the front contacts of relay R are closed. The 90 or clear'indication circuit for signal S is the same as the caution circuit just traced up to and including wire 7, then through wire 13, contact 14 of relay r wire 15, controlling mechanism of signal S wire 9, contact 10 and wires 11 and 1G to battery 4; it will be seen that this circuit can be closed only when the front contacts of relay R and the contact of relay 0 are closed. Relay R is therefore the caution indication relay and relay 7 the clear indication relay, for signal S 1 Signal S is similarly controlled by relays R and r corresponding to relays R and r Signals S S and S are controlled respectively by signal relays R B and R, each of which relays is of the polarized type. The 45 or caution indication circuit for signal S is from battery 17, through wires 18 and 19, front contact 20 of relay It, wire 21, controlling mechanism of signal S, wire 22, front contact 23 of relay It, wire 24. to battery 17; it will be seen, therefore, that the caution indication circuit of signal S will be closed whenever relay R is energized regardless of the direction of the flow of current through the coils of this relay. The 90 or clear indication circuit for signal S is the same as the caution circuit just traced up to and including contact 20 of relay R, then through wire 25, polarized contact 26 of relay It, wire 27, controlling mechanism for signal S, then as before to battery 17; it will be seen, therefore, that the clear indication circuit for signal S is closed only when relay R is energized in such direction that contact 26 swings to the left. The circuits for signals S and S are similar to those just traced for signal S. The caution indication circuit for signal S is controlled by relay R and the clear indication circuit for this signal is controlled by relay r, these circuits being similar to the corresponding circuits for signal 8 The control of relays R R R, R and W will be explained hereinafter.

1 will first explain the control and operation of the end signals 8 and S during the passage of a train through the stretch A B, and will later take up the control and operation of the intermediate signals S 3*, S and S. Relays R and R as has been hereinbefore pointed out, are differential relays each comprising two coils 1 and 2. Coil 1 of each of these relays is a local coil, the circuit for this coil of relay B being from battery H through wires 28 and 29, contact 30 of track relay T wire 31, contact 82 of track relay T wire 38, relay coil 1, and wires 34-, 85 and 36 to battery H The circuit for coil 1 of relay R is similarly energz'ized from battery H and controlled by track relays T and T Coil 2 of each relay R and R is a line coil, and these coils are both included in series in a line which may be energized from either battery H or H Normally, that is, when no train is between points J and G, the ends of this line are connected with the positive terminals of bat teries H and H so that no current then flows therein. This line isfrom the positive terminal of battery H through wires 11, 12 and 1-3, front contact 89 of track relay T wire 14;, back contact of a relay K wire 4C0, coil 2 of relay R wire 47, back contact 48 of relay K wire 49, back contact 50 of relay M wires 51 and 52, front contact 53 of track relay T wire 37, front contact 54;

of relay T", wire 38, front contact 55 of track relay T wire 56, front contact 57 of relay (30, back contact 61 of relay K wire 62, coil 2 of relay R wire (53, back contact 64 of relay K wire 65, front contact 10 of track relay T and wire 28 to positive terminal of battery H The negative terminals of batteries H and H are, of course, connected with the common wire 0. It will be seen, therefore, that when no train is between points J and Cr there is no current flowing in coil 2 of either relay R or R If new a train moving from east to west passes point C it denergizes track relay T thereby disconnecting wire (55 from the positive terminal of battery H and connecting it with the negative terminal of this battery through wires 66 and 36. Current then flows from battery 1'1 through the relay coils 2,'and the direction of this current in relay R is such that it opposes the effect of current in coil 1 of this relay, so that this- A relay opens, thereby causing signal S to change to the stop position, thus preventing the entrance of a train into the stretch A- B moving from east to west. The opening of track relay T opens the circuit for coil 1 of relay R but the current in coil 2 of this relay serves to hold the front contacts of this relay closed, so that signal S remains'in the clear 13051131011.

I will assume that the characteristics of relays R and R are as follows, based on the pick-up current or voltage as unity: Pick up:'1.00. Release:.et0. Coils 1 each have .80 pick up of relay. Coils 2 alone each have 1.20 pick up of relay. Coils 2 in series each have .60 pick up of relay. Then when coils 2 are energized in series as above, the condition 1n relay 1s follows: Coil 1:.80.

Coil 2 .60 in opposition. The difference is .20 which is less than the releasing value so that the relay opens. In relay R the conditions are as follows: Coil 1:.00. Coil 2 .60. The sum is .60 which is greater than the release value so the relay remains closed.

When the train enters section BF it opens track relay T, has continuing to hold open the circuit for coil 1 of relay R The shifting of contact 55 from its front to its back contact opens thecircuit for coil .2 of relay It, so that the contacts of this relay then open, allowing signal S to move to the stop position. During the early part of this movement of signal S that is, while circuit controller 68 operated by this signal is still lay M wire 72 and common wire 0 to battery H Coil l of relay K is constantly energized, the circuit being from positive terminal of battery H through wires 28, 73, 74 and 75, coil 1 of relay K wire 70,

back contact 71 of relay M wires 72, 76,

and 36 to battery H The characteristics of relay K (and of the corresponding relay K are the same as those of relays R and R hence the conditions in this relay are as follows: Coil 1:.80 pick up. Coil 2:.60 pick up. The total is 1.40 pick up, so the relay (K closes. When the circuit controller 68 opens it opens the circuit including coils 2 of relays K and R but relay K remains closed because of the .80 current in its coil 1, and relay B does not pick up because the current in its coil 1 is only .80 of the pick up value.

When the train leaves section B-F and enters section FE, the o'peningor track relay T causes signal S to change to the stop position for reasons which will be pointed out hereinafter. The closure of track relay T closes the following circuit through coil2 of relay R from battery H through wires 28 and 77, contact 7 8 of relay T Wire 7 9, front contact 61 of relay K (which is now closed), Wire 62, coil 2 of relay R wire 63, front contact 64, wires 80, 35 and 36 to battery H The closure of track relay T also closes the local circuit for coil 1 of relay R so that both coils are now energized and in such directions as to assist each other. The condition in this relay is then 1.20+.80=2.00 pick up, hence the relay closes and signal S therefore moves to caution. This signal does not move to the clear position because the clear relay r was previously opened and remains open by reason of means which will be explained hereinafter.

When the train enters section EA, the opening of track relay T causes current to flow in coil 1 of relay M and coil 2 of relay M in series, the circuit being from positive terminal of battery HP, through wires 28, 73 and 81, contact 82 of relay K wire 83, coil 1 of relay M wire 84, circuit controller 85 (closed when the switch into siding D is normal), wire 86, contact 55, wire 38, contact 54, wire 37, back contact 53, wires 87 and 87 contact 88 (closed when signal S is in stop position), wire 89, contact 90, wire 91, coil 2 of relay M wire 92 and common wire 0 to battery H Relays M and M are so de signed that when coil 1 of M and coil 2 of M are in series the current flowing in each is 1.20 of the pick up value, hence each of these relays closes. The closure of relay M opens at contact 71 the circuit for coil 1 of relay K and the circuit for coil 2 being already open this relay opens. The opening of relay K opens at contact 82 the circult for relays M and M hence relay M opens. Coil 2- of relay M is now energized by current from battery H flowing through 28, 28 28 40, 65, 64, 63, coil 2 of relay R 62, 61, 60, 59, 58, 57, 56 and 55, then through the line circuit as before hence if relay M opens while relay M is closing and opening 1t again becomes picked up. As the train passes on into section AJ it opens track relay T and later allows track relay T to close, so that the line circuit then includes in series the coils 2 of relays R and R and coil 1 of relay M This circuit is the same as before from the positive terminal of bat tery H up to and including contact 53 of relay T then through wires 52 and 93, circuit controller 94 (closed when the switch leading into siding C is normal), wire 95, coil 1, wire 96, contact 50 (which is already closed), then through 49, 48 and 47, coil 2 of relay R 46, 45, 44, back contact 39 of re lay T and common wire 0 to battery H Although the normal circuit of coil 1 of relay R is now open at contact 131 of relay T yet this coil is now energized because relay M closes a shunt around contact 131; the circuit for this coil is now from battery 1:1 through wires 41, 42, 122 and 123, contact 124, wires 125, 126 and l27, contact 128, wire 129, coil 1, wire 130 to battery H The current in coil 2 of relay R now flows in such direction as to assist coil 1, but owing to the resistance of coil 1 of relay M the current in coil 2 of relay R is reduced to .30, so that the condition in relay R is .80+.30:1.10. This relay therefore then closes, so that signal S returns to the clear position. In relay R the current in coil 2 opposes that in coil 1, so that the condition is .80.30:.50, which is above the release point so this relay remains closed. As the train passes out of section AJ, track relay T closes thereby restoring the line circuit to its original condition. Helay M now opens, and since relays R and R are both closed they remain closed by virtue of their local coils 1, 1.

The operation of the apparatus during the passage of a train from J to G moving toward the east would be in all respects similar to the operation just described during the passage of a west-bound train.

I will now explain the control and operation of the intermediate signals S S S and S, and the control of the clear indication relays r and r for the end signals. As the train moving toward the west enters section 13-]? it opens track relay T and this in turn opens a circuit including relays r and R in series. This circuit is from battery 4 through wire 5, contact 154. wire 155, relay 1*, wire 97, pole-changer P wire 99, relay R wires 100 and 101, common wire 0, wire 102, pole-changer P wire 103, to battery 4. Signal S was previously placed in the stop position by means which will appear when the corresponding signal S is considered, hence pole-changer P was reversed so that the current flowing in the circuit just traced was in such direction that relay a was holding signal S in the caution position. This relay now opens so thatsignal S changes to stop. The opening of relay 7' has no effect on signal S be cause this signal was placed at stop by the opening of relay R as has been hereinbefore explained. As the train passes into section FE, the opening of track relay T opens the circuit for relay R, which circuit is from battery 104: through wires 105 and 106, contact 107, wire 108, relay R, wires 109 and 110 to battery 104. The opening of relay R causes signal S to go to stop, and also opens a circuit including relays r and R in series, which circuit is from battery 10 1 through wires 105, 106 and 111, contact 112, wire 113, relay r wire 114:, pole changer P", wire 116, relay R vires 117, 101, O and 118, pole-changer P and wire 11.0 to battery 101. The opening of relay R places signal S at" stop. Signal S now changes to caution owing to the closure of relay R as hereinbeforc explained, and signal 8, which had previously changed to. caution, now changesto clear as will here inafter appear in considering the corresponding signal S. 7 As soon as relay R closes, the circuit including battery 1, and relays r and R is closed; relay It then closes, and owing to the fact that signal S is clear this relay is energized in'such direction as to cause signal S to move to the clear position. The resistance relay R is however such that the current in relay 7 is insutlicient to cause the latter relay to close, hence signal S moves only to the caution position. As the train passes into section EA it opens track relay T thereby opening a circuit including relays r and R, which circuit is from battery 156, through wires 1.57 and 158, contact 159, wire 160, relay r wire 161, front contact 162, wires 163 and 161, relay R wires 165, 166, O and 167, front contact 168, wire 169 to battery 156. The opening of relay causes signal S to change to stop indication, but the opening of relay 7' has no offeet because relay R is already open. The opening of track relay T by the entrance of the train into section F-A also places signal S at stop, the circuit for relay R for this signal. being from battery H through wires 11, 170 and 171, contact 172, wire 173, contact 17 41, wire 175, pole-changer P wires 17 6 and 191 contact 192, wire 193, relay R wires 19 1 and 151, pole-changer P wires 190 and 18a to battery H It should be noted. at this point that during the passage of an eastbound train, signal S changes to caution when the train passes point A because relay K which is then closed forms a shunt around contact 172 of track relay T E for westbound movements is that if this were not done, two trains moving in opposite directions might meet nose to nose at point 11; this would not be a serious matterhowever, because signals S and S would both be at stop and the trains would have previously received caution signals at S and respectively.

As the train leaves section F-E it allows track relay T* to close, so that relay R closes causing signal S to move to the caution position. The closure ofrelay R closes the circuit from battery 10% through relay 7 and relay Pifland owing to the fact that signal S is now. clear a shunt is closed around relay R which shunt comprises wire 198, contact 199, wire 200, circuit controller 133, resistance 13 1 and wire 135. The shunt was not closed until relay R closed hence the current in relay R was suilicient to close thisrrelay, and owing to contact 202, wire 136, circuit controller 137,

ing to this shunt being closed the current in relay r is now sufficient to close this relay so that signal S moves to the clear position. The shunt just traced was not closed until relay 1t became closed, henceit did not interfere with the closing of relay R But the current which flows in relay R after the shunt closes is suflicient to hold this relay closed. As the train proceeds into section AJ, it opens track relay T and allows track relay to close, thereby causing the closure of relay R as has been hereinbeiore explained. The line circuit includ ing relays R and r is now closed, but owing to the fa ct thatrelay X new opens, for reasons explained hereinafter, thecontaets of which constitute a pole-changer in the circuit of relay R the latter relay is energized in such direction that signal 8 moves only to the caution position. This movement of signal S reverses pole-changer P therebyreversing relay R so that signal S then moves to the clear position. Relay 9 closes becauses the shunt around relay R (which corresponds to the shunt around. relay R hereinbefore explained) is closed, hence signal S changes to the clear position.

The opening of track relay T opens at contact 1 18 the circuit of relay R which controls signal 5, so that this signal moves to danger as the train enters section AJ. The circuit for relay R is from battery H through wires 1411 and 1 12, contact 143, wire 14A, contact 145, wire 1&6, pole-changerl wire 147, contact 148, wire 149, relay R wires 150 and 151, pole- changer P wires 152 and 153 to battery H When the train proceeds to a certain point beyond the siding O, relay X will close as hereinafter explained, and since the contacts of this relay constitute a polechanger for relay R the latter Will then reverse so that signal S will move to the clear position. The operation of the intermediate signals S S S and S during the passage of an east-bound train through the stretch AB is similar in all respects to their operation during the passage of awestbound train.

It now remains to explain the control and operation of the relays X and X and to explain the control exerted upon the signals by these relays, but before doing so the desired operation of the signals affected by these relays will be briefly stated. When a train moving toward the west enters section G-B, it causes signal S to change to stop as has hereinbefore been explained, and this causes signal S to change to caution be cause the relay R for the latter signal is controlled by pole-changer P operated by signal S (The circuit for relay R is similar to that for relay R traced hereinbefore). In addition, it is desired that signal S should also be placed at caution when the train enters GB, and held there while the train occupies any part of the stretch from G to The reason for this is as follows: While a west-bound train is in stretch AB, if an east-bound train should pass signal S at clear the latter train would be justified in approaching signal S at high speed expecting to find this latter signal at clear or caution. If in the meantime the west-bound train has passed point E it has caused signal S to change to stop and the east-bound train would then be unexpectedly confronted with a stop signal. To avoid this surprise, it is preferable to cause signal S to indicate caution as soon as a. west-bound train enters section GB; but in order to permit following movements without interruption or delay, the control of signal S should also be such that this signal changes to caution when an east-bound train passes signal S and to clear when the train passes signal S This control is effected by relays X and X, the

control and operation of which are as follows: Relays X and X are of a dilferential type, each comprising two coils 1 and 2. Coil 2 of each relay is provided with a. local circuit which is normally closed, this circuit for relay X being from battery H through wires 41, 17 0 and 171, contact 17 2, Wire 173, contact 174, wire 175, pole-changer P wire 176, back contact 177, wire 178, circuit controller 179, wires 180 and 181, coil 2, wires 182, 183, and 184 to battery H The circuit for coil 2 of relay X is similar and is controlled by circuit controller 185, contact 186, pole-changer P", and relays T and T. The current thus flowing in each of these coils is suliicient to pick up the relay. When a westbound train enters section GB it causes 1 signal S to move to stop 'as has been hereinbefore explained, thus reversing polechanger P and this operation of the polechanger opens the circuit just traced for coil 2 of relay X But the movement of the pole-changer also closes a circuit including the two coils 1 of relays X and X in series, which circuit is from battery H through wires 141 and 142, contact 143, wire 144, contact 145, wire 146, pole-changer P wire 147, contact 186, wire 187, circuit controller 185, Wire 188, coil 1 of relay X wire 189, coil 1 of relay X wire 180, circuit controller 179, wire 178, contact 177, pole-changer P (which is now reversed), wires 190, and 184, battery H wires 41, 170 and 171, contact 172, wire 173, contact 174, wire 175, polechanger P wire 151, pole- changer P wires 152 and 153 to battery H Relay X therefore remains closed, and relay X is so designed that the combined voltages of batteries H and H in coil 1 neutralizes the effect of current from battery H in coil 2 so that this relay opens. The contacts of relay X constitute a pole-changer in the circuit of relay R, in exactly the same manner as do the contacts of relay X in the circuit of relay R as hereinbefore explained, hence relay R reverses and signal S changes to caution. No change occurs as far as relays X and X are concerned until the train passes point E; at this time the opening of track relay T opens the series circuit just traced for coils 1, but it also places signal S at stop as hereinbefore explained, and the circuit controller 185 operated by this signal opens the local circuit for coil 2 of relay X so that this latter relay does not close. The opening of the series circuit also causes relay X to open, and this relay continues to be held open by circuit controller 179 of signal S when the train passes the latter signal. As the train passes signal S the opening of track relay T holds open the circuits for both coils of relay X so that latter relay causes signal S to indicate caution. As the train passes point J it continues to hold signal S at stop which signal, through its circuit controller 17 9, holds relay X open. As the train passes signal S, the opening of track relay T places signals S and S at stop, and signal S changes to caution. The consequent closure of circuit controller 1.7 9 closes the local circuit for coil 2 of relay X, which relay then closes thus causing signal S to move to clear position. At this time, signal S also changes to clear position, so that when the train passes signal 8, allowing relay T to close, the local coil of relay X becomes closed so that this relay closes. Relays X and X are then in the same conditions as shown in the drawing. During the passage of an east-bound train, relay X is opened when the train approaches the stretch to the left of siding C, thus placing signal S at caution, but relay X does not open hence signal 8 remains at clear. The operation of relays X and X is simi lar during an east-bound movement to that just explained for a west-bound movement, hence no further explanation is necessary.

Referring now to Fig. 2,, the apparatus here shown is similar to that shown in Fig. 1 except that I have provided additional means for so controlling the intermediate signals that as a train approaches the stretch in either direction both intermediate signals governing traflic in the opposite direction are placed at stop. To accomplish this I provide for each intermediate signal a relay designated by reference character Z with the same exponent as that of the reference character for the corresponding signal. Each of these relays Z to Z is similar in structure and characteristics to relays R and R The caution and clear indication circuits for each signal are controlled by the corresponding relay Z, these circuits being the same as in Fig. 1 except for the inclusion of contact 204 in each circuit. Coil 1 of each relay Z is constantly energized by a local circuit as is obvious from an inspection of the drawing, and the coils 2 of all of the additional relays Z are included in series in the line circuit comprising wires 37 and 38. The operation is as follows: When a train moving toward the west passes point G it causes the flow of current through the coils 2 of all relays Z, the action of relays R and B being the same as before. The relative directions of the currents in coils 1 and 2 of relays Z and Z are such that these relays remain closed, but the relative directions of the currents in the two coils of relays Z and Z are such that these relays open, thus placing signals S and S at stop. Relays Z' and Z remain open, and signals S and S therefore remain at stop, until the train enters section E-A at which time current flows from battery I-I through coils 2 of relays Z and of relay M in the reverse direction. This current is so weakened by the resistance of coil 2 of relay M that it does not cause relays Z and Z to open, but it is suflicient to cause relays Z and Z to close, its efiect being added to that of the currents in coils 1 of the latter relays. When a train moves toward the east, the operation will be similar, that is, relays Z? and Z will be opened to place signals S and S at stop, and will later be closed as the train is about to leave the stretch A-B. The operation of the system shown in Fig. 2 is in all other respects similar to that of the system shown in Fig. 1.

Although I have herein shown and described only two forms of signaling systems embodying my invention, it is understood that various changes and modifications may be made therein within the scope of theappended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track, signals at opposite ends of the stretch for governing the entrance of trains into the stretch, a relay for the control of each signal each relay comprising two coils, a source of current adjacent each end of the stretch, means for normally energizing one coil of each relay from the adjacent source of current to hold the relay closed, and means controlled by a train approaching one end of the stretch for connecting the two remaining relay coils in series with one of said sources, the currents in the two coils of the relay at the end of the stretch remote from the train being then in such relative directions as to oppose each other whereby that relay opens and the signal controlled there by changes to stop indication, and means controlled at the same time by the said train for opening the circuit of the locally energized coil of the relay at the end of the stretch nearest the train whereby that relay then is held closed by the current in its other coil.

2. In combination, a section of railway track, two signals at opposite ends thereof for governing traffic into the stretch, a polar ized relay for controlling one of said signals and a clear indication relay and a caution indication relay for controlling the other signal, a track circuit for the stretch for controlling said caution indication relay, a line circuit controlled also by said track circuit and including said clear indication relay and said polarized relay and a source of current, a shunt around the polarized relay, said polarized relay being effectively responsive to the current flowing therein when the line circuit is closed irrespective of whether or not the shunt is closed and said clear indication relay being effectively responsive to the current in the line circuit only when the shunt is closed, means for opening said shunt controlled by a train beyond the end 'of the section at which is located the signal controlled by the polarized relay, and a polechanger included in said line circuit and controlled by a train beyond the otherend of the section.

3. In combination, a stretch of railway track, two signals as S and S relays X and X for controlling said two signals respectively, each relay comprising two coils 1 and 2, sources of current H and H for said relays, means for normally energizing coil 2 of each relay from the adjacent source of current whereby each relay is normally closed, means controlled by a train in the rear of either of said signals for disconnect ing coil 2 of the relay for the signal nearest said train from its source of current and for connecting coil 1 of each relay and the two sources of current all in series whereby the relay for the signal nearest the train remains closed because of the current in its coil 1, the current in coil 1 of the other relay being then of such value and in such direction as to counteract the effect of the current in coil 2 thereof whereby the latter relay then opens.

41. In combination, a stretch of railway track, two signals as S and S relays X and X for controlling said two signals re spectively, each relay comprising two coils 1 and 2, means for normally energizing coil 2 of each relay whereby said relays are normally closed, means controlled by a train approaching either signal for deenergizing coil 2 of the relay for the signal nearest the train and energizing coil 1 of both relays, whereby the relay for the signal nearest the train remains closed by virtue of the current in its coil 1, the current in coil 1 of the other relay being then of such value and direction that it counteracts the effect of coil 2 whereby the latter relay opens.

5. In combination, a stretch of railway track, two signals as S and S relays X and X for controlling said two signals respectively, each relay comprising two coils 1 and 2, means for normally energizing coil 2 of each relay whereby said relays are normally closed, and means controlled by a train approaching either of said signals for energizing coil 1 of the relay for the signal farthest from the train with current of such value and direction as to counteract the effect of the current in coil 2 of that relay whereby the relay opens.

6. In combination, a stretch of railway track, signals located at intervals for governing traific in one direction through the stretch, and other signals located atintervals for governing traffic in the other direction through the stretch, a relay for each of said signals each relay comprising two coils 1 and 2, means for constantly energizing coil 1 of each relay, and means controlled by a train approaching the stretch in either direction for energizing coil 2 of each relay in one direction or the other according to the direction of movement of the train, the relay coils being so wound and connected that the two coils of the relays for the signals governing traliic in the direction of movement of the approaching train assist each other to hold such relays closed, and that the two coils of each of the other relays oppose each other whereby the latter relays open.

In testimony whereof I aflix my signature in presence of two witnesses.

HARRY D. ABERNETHY.

Witnesses J. O. BRANCH, G. T. GREENFIELD.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C.

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