US1810096A - Railway traffic controlling apparatus - Google Patents

Description

June 16, 1931. H. A. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed May 5, 1926 INVENTOR H'H l allacc,

WQ'RW l||l flllllII-IIIIIIIL Patented June 16, 1931' HERBF T A. W'AIJLACE, 0F EDGEVIOOD, PENNSYLVANIA, ASSIGNGR TO THE UNION S'WITCH 8c SIGNAL COMPANY, OF SWISSVA'LE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA RAILWAY TRAFFIC CONTROLLING APPARATUS Original application filed. May 5, 1926, Serial No. 106,871. Divided. and this application filed. August 5,

1929. Serial ternating current is normally supplied to the rails, but that under certain conditions periodically interrupted current'is supplied to the rails, the characteristic of the periodic interruptions being controlled in accordance with traffic conditions.

The present application is a division of my co-pending application, Serial No. 106,871, filed May 5, 1926, for railway traffic control ling apparatus. v

I will describe oneform of trackway apparatus embodying my invention, and will then point out the novel features thereof in claims. f I

The accompanying drawing is a diagram-.

r1 matic view illustrating one form of trackway apparatus embodying my invention as applied to two parallel tracks connected by crossovers.

Referring to the drawing, the reference characters d and e designate two parallel railway tracks along which traffic normally moves in the direction indicated by the arrows. Track e is divided into two track sections GH and H-J by means of insulated joints 2. The portion of track (Z which is opposite sections G-H and HJ is insulated from the rest of track (Z by insulated joints 2 to form a track section EF. Section G-H is connected with section EF by means of a crossover designated in general by the reference character 9, the switchesof which are operated by means not shown in the drawing and forming no part of the present invention. A circuit controller designated by the reference character VV is controlled. in accordance with the positions of the switches which connect the crossover g with the two track sections. The position of the switches of crossover 9 for which the circuit controller W is closed is indicated'in the wiring diagram by letters inclosed by circles which are in turn designated by the reference character W For example, on the left-hand side of the sheet close to relay Z are two contacts on circuit controller W The upper one of these contacts is indicated by acircle inclosing the letter R, and the lower contact is indicated by a circle containing the letter N. These symbols mean that the lower or normal contact N is closed when the switches of crossover 9 are in their normal positions, that is, when these switches are in such positions that traflic can proceed on track 6 through section G-H. When the switches of this crossover occupy their reversepositions, however, to

permit traffic to move from section G H into section'E-F over the crossover 'g, the other or reverse contact designated by the reference character R is closed.

In similar manner a crossover 7L connects section EF with section H-J, and the switches of this crossover control a circuit controller W. The contacts of this circuit controller are designated on the drawing by symbols similar to those just explained in con nectionwith the circuit controller W It will. be noticed that certain of'the contacts of circuit controllers W and W are marked GR. This means that the contacts so designated are closed when the associated switches are in the reverse position, and re main closed when the. switch moves away from the reverse position toward the normal position until the switch is vpast the center or C position. In similarv manner contacts marked CNtare closed when the switch is in the center position, the normal position or any position between these two. k

- Current is at times supplied to the rails of each section of tracks d'and' e by means of a transformer designated by the reference character T with an appropriate distinguish relay designated by the reference character 10c R with an exponent corresponding to the location and connected across the rails adjacent the entrance end of the section.

Traffic entering stretch (Z is governed by a trackway signal TE, and traflic entering stretch e is governed by a similar trackway signal r. As shown in the drawing each of these signals 1 is located adjacent the entrance end of the stretch of track which it governs, and comprises a semaphore arm capable of assuming three positions to indicate proceed, caution or stop, but this particular location and form are not essential to my invention. In actual practice the signals 7' will usually be controlled manually from a remote point such as an interlocking cabin so that they normally indicate stop but can be caused to indicate caution or proceed when the operator in the cabin wishes to permit traffic to enter the stretch of track governed by these signals. WVhen a train passes the signal, the indication of the signal immediately changes to stop. Associated With-each of the trackway signals r is a circuit con troller designated by the reference character U with the same exponent asthat applied to the signal, and arran ed to be closed only when the signal gives a proceed or caution indication.

Associated with each track relay R is a stick relay designated by the reference character Z with. the same exponent as that applied to the track relay. Referring particularly to stick relay Z this relay is provided with a pick-up circuit which may be traced from terminal a of'a suitable source of current, through back contact 94 of track relay R wires 95 and 96, circuit controller U controlled by signal r gwires 97 and 98, winding of relay Z and wire 99 to terminal 2') of the same source of current. This circuit is closed only if relay R becomes de-energized when signal r indicates proceed or caution. But if the de-energization of relay R results from the entrance of a: train into section GH, signal r goes to stop as soon as the train passes the signal, thereby opening circuit controller U and interrupting the pickup circuit just traced. The relay Z having become energized, is maintained in its energized condition over a stick circuit which passes from terminal-a, through back contact 9% of relay R wires 95 and 100, front-conta ct 101 of relay Z wires 102 and 98, winding ofrelay Z and wire 99 to terminal 6. Relay Z having once been energized, therefore, is maintainedin its energized condition as long as relay- R remains de-energized.

Stick relay Z is provided with one pick-up circuit which may be traced from terminal a, through back contact 83 of relay R wires 83 and 84, circuit controller U wires and 86, windingof relay Z and wire 87 to terminal 6. The relay isalso provided with a second pick-up circuit which may be traced from terminal a, through a reverse contact on circuit controller wire 91, front contact 92 of relay Z wires 93, and 86, Wind ing of relay Z and wire 87 to terminal 0. Relay Z therefore becomes energized if a. train enters section EF with signal W at proceed, or if relay Z becomes energized due to the entrance of a train into section G-ll when the switches of crossover g' are reversed to permit this train to run into section E-F. Having once been energized, relay Z is maintained in its energized condition as long as relay R is tie-energized, by virtue of a stick circuit which passes from terminal a, through back contact 83 of relay R wires 83 and 88, front contact 89 of relay Z wires 90 and 86, winding of relay Z and wire 87 to terminal b.

if a train enters section HJ from section Gl-l with the switches of crossover g in their normal positions and relay Z energized, the de-energization of relay R com pletes a pick-up circuit for relay Z which circuit is from terminal a, through back contact 103 of relay R wires 10% and 111, a normal contact N on circuit controller W wire 112, front contact 118 of relay Z wires 11%, 108 and 109, winding of relay Z and wire 110 to terminal Z). If a train enters section H-J with relay Z energized and the switches of cross-over h reversed, as is the case when the train enters the section from section EF over the crossover, relay R becomes; ale-energized and relay R becomes energized by a circuit which passes from terminal. a, through back contact 103 of track relay R wire 10-l, a reverse. contact R on circuit controller-WV, wire 105,- front contact 106 of relay Z wires 107, 108 and 109, winding of relay Z and wire 110 back to terminal Z) thereby picking up relay Z Having once been energized overeither of the pick-up circuits just traced, relay Z is subsequently held in its energized condition as long as relay R remains de-energized, the stick circuit being from terminal a, through back contact 108 of track relay R wires 104, 111 and 115, front contact 116 of relay Z Wires 116 and 109, winding of relay Z and wire 110 to terminal 3).

Associated with each stick relay Z is a coding device designated by the reference character K with a suitable exponent. Each coding device K comprises two magnetsS and 9, and a pivoted armature 4-9 biased to a central position but arranged to be attracted by one or the other of the magnets. Carried by the armature 49 are movable contacts 11 and 14-, which swing to one side or the other, depending upon which of the magnets 8 or 9 is attracting the armature. Referring. particularly to coding device K the circuit for this device is from terminal a,.thro ugh front contactll? of relay Z, a: rectifier 10, magnets -8 and 9 of device K to terminal I). The device K isintended to the device is de-energized.

operate on direct current, and since the source of energy, the terminals ofwhich are a and b, is a source of alternating current, the rectifier 10 is included in the circuit for the coding device to change the alternating current supplied thereto'to unidirectional current. It will be seen that contact 1111 is arranged to short circuit magnet 9, and that contact 1111 is arranged to short circuit magnet 8. The contacts are so arranged that when the coding. device is de-energized, contact 11-11 is closed. If, therefore, the operating circuit for device K becomes closed, current will be supplied to magnet 8, but will be shunted around magnet 9 by contact 1111 Armature 49 will, therefore, be attracted by magnet 8 to open contact 1111 and close contact 11-11 Current will then be supplied to magnet 9, and magnet 8 will be short-circuited. The magnets 8 and 9 are arranged to be slow acting, so that an interval of time will elapse before the increasing flux in magnet 9 will overcome the decreasing flux inmagnet 8 to a suflicient degree to again reverse armature 49. At the expiration of this time interval, armature 49 will swing backtoward magnet 9, so that contact 1111 will be open, and contact 1111 will be closed. Another time interval will elapse before armature 49 is again reversed. It follows that when the operating circuit for device K is closed, the armature 49 will oscillate, so that the contacts controlled by this armature are operated intermittently. The contacts 1414 and 14-14 are so adjusted that they are both closed when When the device becomes energized, however, these contacts are opened alternately. The parts are so arranged, as indicated by the unequal shunting bands on the magnets 8 and 9, that when the device K is operated, contact 1414 is closed for a larger proportion of each cycle that is contact 14 14 For example, assuming that a complete cycle of operation ofthe device requires one second, the contacts may be so arranged that contact 14-14 is closed.

for two-thirds of a second, and contact 1414 is closed for one-third of a second.

, As shown in the drawing, relays R and R are energized, the switches of crossovers g and h are in their normal positions and signals T and TE are indicating stop. A. cir-. cuit, is therefore closed from terminal a, through front contact 118 of relay R wire 119, a CN contact of circuit controller W wire 183, a CN contact on circuit controller 1V wire 120, contact 1414 of coding device K wire 121, and primary 4 of track transformer T to terminal 1). Current is therefore supplied to the rails of section EF by transformer T Relay R is energized, so that relay Z is de-energized. The circuit for coding device K is open at front contact 117 of relay Z so that the coding device is de-energized and contact 1414" is continuously closed. It follows that the current supplied to the track rails of section EF, under theseconditions, is uninterrupted. The circuit for transformer T may be traced from terminal a, through front contact 122 of relay R wire 123, a CN contact on circuit controller W wire 124, contact 14-14 of coding device K wire 125, and primary 4 of transformer '1 to terminal 6. The current thus supplied to the rails of section H-J energizes relay R so that relay Z is de-energized and device K is also de-energized. Contact 1414 of this coding device is therefore continuously closed and the current supplied to the section HJ is uninterrupted. Another circuit is closed from terminal a, through front contact 1220f relay R wire 123, a CN contact on circuit controller W wire 126, a CN contact on circuit controller wire 127, cont-act 1414 of coding device K ,wires 128 and 129, front contact 130 of relay R wire 131, a CN contact on circuit controller W wire 132, and primary 4 of transformer T back to' terminal I). It will be seen that this circuit is closed only when the switches for both crossovers g and h occupy their normal'positions and when both relays R and R are energized. The current thus supplied to section GH by transformer T energizes relay R Relay Z is therefore de-energized and coding device K is also de-energized. Contact 1414 of relay K is therefore continuously closed and the current supplied to the rails of section GH is uninterrupted.

I will now assume that signal W is moved to the proceed position and that a train moving from left to right passes along track d. When this train enterssection E-F, relay R will become de-energized, and the pickup circuit for relay Z through circuitwcontroller U will be closed, thereby energizing this relay. The closing of front contact 117 of this relay will energize coding device K so that contact 1414 of device K will be operated intermittently. The circuit for primary 4 of transformer T will therefore be periodically interrupted so that current will be supplied to section E--F in accord ance with the proceed code. The signal a will move to the stop indication as soon as thetrain enters the section, but relay Z will be held, energized by its stick circuit so that the proceed code will be supplied to the train as it moves through the section. When the train leaves section E F, relay will pick up,breaking the stick circuit for relay Z and de-energizing this relay. Device K will therefore become de-energized, and the interruptions of the current supplied to section EF will cease. tion to the right ofpoint F, relayR will be de-energized so that current will flow from With the train in the secterminal a, through back contact 118 of relay R wire 13 1, a GN contact on circuit controller Vi wire 185, a UN contact on circuit controller VJ, wire 136, contact 14 -1 1 of device K wire 121, and primary 4 of transformer to terminal I). If, now, a second train enters section EF, passing signal 0' at proceed, relay Z will again be picked up, and will be held up by its stick circuit after signal 1 is returned to its stop inclication. The energization of device K resulting from the closing of contact 117 of relay Z will cause the circuit just traced for primary 1 of transformer T to be periodically interrupted at contact 1 11 1 so that current will then be supplied to section IL -l in accordance with the caution code.

I will now assume that the switches of crossover 72, are reversed so that traf ic is permitted to move fromsection EF into section HJ. All R contacts and GR contacts on circuit controller V1 will therefore be closed, and all f contacts and CN contacts on this circuit controller will be open. Current will then flow from terminal a, through a CR contact on circuit controller VV wires 137 and 136, contact 1414 of device K wire 121, and primary 4 of transformer T back to terminal 2). Current will also be supplied to transformer T over a circuit which may be traced from terminal a through a CR contact on circuit controller wires 139, 1aand 1 11, con tact 1l-14; of relay K wire 125, and primary 1 of transform-er T to terminal 6. If now a train enters section llll passing signal W at proceed, relay Z will become energizedas before and device K will operate to interrupt the supply of current to the primary 4 of transformer T in accordance with the caution code. The train will therefore be supplied with the caution code from transformer T as far as the crossover 71,. When the train proceeds over the crossover it, and enters section HJ, it will shunt relay R and this will close the pick-up circuit for re lay Z so that the coding device K will be set into operation. lhe operation of the device K will interrupt the currentsupplied to transformer T in accordance with the caution code. It follows that when the switches of crossover h are reversed to permit a train movement from point E to point J, a cantion indication will be received on board a train passing along this route irrespective of the condition of the track relays connected with the rails to the right points If and J.

I will neXt assume all the switches are normal, that relays R and R are energized, that signal 1* indicates proceed, and that a train moving in the direction of the arrow passes this signal moving along the track 6. The de-energization of relay R will complete thepick-up circuit for relay Z which will thereupon become energized and will complete its stick circuit over its own front contact 101 and back contact 9 1 of relay R The closing of front contact 11'? of relay FI wi l energize the coding device K so that co tact i l-1 of this device will periodically interrupt the circuit hereinbefore traced for primary l of transformer T Current will therefore be supplied to the rails of sec tion Gl-l in accordance with the proceed code. VJ hen the train enters section J, the de-energization of relay R will complete a pick-up circuit for relay Z over an N contact on circuit controller W and front contact 113 of relay 'Z Relay Z will there fore become energized, "and will be maintained in its energized condition, as long as relay R is deenergized,v by virtue of its stick circuit including front contact 116 of the relay Z and back contact 103 of relay R Device K will therefore be energized, and contact 1-11-l of this relay will operate to periodically interrupt the supply of current to the primary 1 of transformer T in accordance with the proceed code. Under these conditions, therefore, when the train is in section G-l-l it will be supplied with the proceed code from transformer T and when the train is in section H J it will be supplied with the proceed code from transformer T When the train is in section HJ, so that relay R is Clo-energized, front contact 130 of this relay will be open and back contact 130 of this relay will beclosed, so that current will flow from terminal a, through back contact 130 of relay R wire 131, a SN contact on circuit controller W wire 132-, and primary 4 of transformer T to terminal Z). A following train entering section G'l-l, under these conditions, will therefore be supplied With uninterrupted alternating current, and so it will therefore receive a stop indication. 7

1f relay RF is (lo-energized when a train passes signal 1 at proceed, the entrance of the train into section will energize device K as before, and current will be supplied from terminal a through back contact 122 of relay R wire 148, a CN contact on circuit controller W wiresl lt) and 144, a 0N Contact on circuit controller W wire 1 15, contact 1-f14 of device 1 wires 128 and 129, front contact 130 of relay R wire 131, a CN contact of circuit controller Vi wire 132, and primary 4: of transformer T to terminal Z). Under these conditions current will be supplied to the rails or section Gl-l in accordance with the caution code. VJhen the train enters section l-lJ, the deenergization of relay R will operate to energize device l? as explained hereinbefore. Current will then flow from terminal a, through back contact 122 of relay R wire L13, a UN contact on circuit controller W wires 1410 and 1 11, contact 14714? of device K wire 125, andprimary e of transformer '1 to cvi terminal 6. Current will therefore be supplied to the rails of section H-J in accordance with the caution code. \Vhen relay R is de-energized, therefore, a train passing along track a will receive current in accordance with the caution code throughout; sections GH and I-IJ. If a following train should enter section GH with the first train still in section HJ, so that relay B is deenergized, the circuit for transformer T would be closed through hack contact 180 of relay R directly to terminal a, so that uninterrupted current would be supplied to section G-H and the following train would receive a stop indication.

I will next assume that the switches of crossover g are reversed to permit a movement of trafiic from section G-I-l into section EF. Circuit controller W will then be reversed so that the R and CR contacts of this circuit controller are closed. If, now, a train enters section (Fr-H, passing sig nal W at proceed relay H will become de-energized so that relay Z willbecomeenergized,

and this will energize device K as explained hereinbefore. The circuit for transformer T under these conditions, is from terminal a, through a CR contact on circuit controller W wires 146 and 145, contact 14--14 of device 'K wires 128 and 148, front contact 149 of relay R a CR contact on circuit controller lV Wires 150 and 132, and primary 4 of transformer T to terminal Z). Current will therefore be supplied to the rails of section GH in accorcL ance with the caution code. became energized; it closed a pick-up circuit for relay Z and the energization of the latter relay caused device K to be set into'operation. This continues after relay Z opens, because of the stick circuit for relay Z which becomes closed when the train enters section of contact 14-14 of device K will periodi-' cally interrupt the circuit for transformer. T, which circuit passes from terminal a, through a CR contact of circuit con troller W Wires 188 and 135, a UN contact on circuit controller W wire 136, contact 1414 of device 'K wire 121, and primary 4 of transformer T to terminal I). The rails of section'EF will therefore be supplied with current in accordance with the caution code, so that when the train enters this section it will receive a caution indication. It should be pointed out that when the train enters section EF, thereby de-energizing relay R the circuit previously traced for primary 4 of transformer T over front contact 149 of relay R becomes opened. and another circuitfor this primary is closed, from terminal a, through wire 147, back contact 149 of relay R a CR contact on cir cuit controller W wires '150 and 132, and

When relay Z9 A following train entering section G-H would therefore be supplied with uninterrupted alternating current and would receive a stop indication.

I will next assumethat the switches of both cross-overs g and h are reversed to permit movements of traflic from section GH through crossover 9 into section EF, and thence through crossover 77. into section I'l -J. If, now,-a train moving in the direction of the arrow passes signal 74* at proceed, the de-energization of relay R willpick up relay Z and so will set device K into operation. The operation of this device will therefore interrupt the current supplied to primary 4 oftransformer T over CR-contact of circuit'controller VV contact 14l4 of device K and front contact 149 of relay R and current will be supplied to the rails of section G-H in accordance with the caution code. The closing of relay Z has also caused relay Z to become energized, and this has caused device K to be set into operation as before. The operation of contact 1414 of this device will interruptthe circuit for primary 4 of transformer T which circuit passes over a CR contact of circuit controller W so that current will be supplied to the rails of section EF in accordance with the caution code. When the train, moving through crossover it enters section HJ,.

contact on circuit controller W and front contact 106 of relay Z so that relay Z will become energized and will then be maintained in its energized condition by its stick circuit. Device K will therefore be energized and will operate to periodically interrupt the current supplied to primary 4 of transformer T in accordance with the caution code. It should be pointedout that when the switches of both crossovers g and 71, are reversed, a train traversing the route which is then set up will'be supplied with current in accordance with the caution code irrespective of the condition of energization of relays R and R If a train passes either of the signals W or W when the signal indicates stop, the corre sponding stick relay Z will not become energized,because the pick-up circuit for each stick relay includes a contact U which is closed only when the signal indicates proceed. If the stick relays do not pickup, the coding relays will not become energized, and if the coding relays do not become energized, the'current supplied to the trackway will not be interrupted in accordance with one of the codes. It follows that if a train passes one of the signals which is not indicating proceed, the train will be supplied with uninterrupted alternating current throughout the stretch,

and cannot receive a caution or a proceed indicatlon.

WVhen a train is proceeding over one of the crossovers g and h, it is necessary to supply current to the rails occupied by the train. In the form of my inventionhere shown, this is accomplished by dividing each ofthe crossovers adjacent its center with insulated joints 155. Referring for example to crossover g, therails 1 and 1. of the lowerportion of the crossover are connected by means of conductors 151 and-152 attached-to the rails adjacent the insulated joints 155 with rails 1 and 1 respectivelyof section GH. Insulated joints 153 are also inserted in the rails 1 and l of section GH immediately to the left of the points of connection of conductors 151 and 152, anda small impedance 154 is. shunted a round each insulated oint 153. It willbe plain therefore that when current is being supplied to the railsof section GH from transformer T5, the potential drop in theimpedance 154 is effectiveto force a current through the conductors 151 and 152 to the rails of the lower part of crossover 9. As soon as the train moving from left to right passes the insulated joints 155, current will besupplied to the train'from transformer T The arrangementof parts for supplying cur Ifentto a train traversing crossover h is similar to the parts just described for crossover g.

Although I have herein shown and de scribed only one form ofapparatus embodying my invention, itis understood that various changes and modifications may be made therein within the scope of the appended claims without departin from the spirit and scope of my invention.

Having thus described my invention, what I claim is: V

1. Railway traffic controlling apparatus comprising a stretch of railway track, a coding device controlled by trafiic conditions, and comprising twonormally closed contacts arranged at times to be operated intermittently so that the contacts are open for different intervals of time, asource of energy, and means for connecting said source with the rails of the stretch over a selected one of said contacts.

2. Railway traffic controlling apparatus comprising a stretch of railway track, I a

transformer having its secondary connected with the rails of the stretch, a repeater relay controlled in accordance with traffic conditions, a coding device controlled by traffic conditions and comprising two normally closed contacts arranged to be opened intermittently when the coding device is operated so that the contacts are closed for different proportions of a given interval oftime, a circuit for the primaryof said transformer including a front contact of said repeater relay and one contact of said coding device, and a second circuit for said primary including a back contact of said repeater relay and the remaining contact of said coding device.

3. In combination, a stretch of railway track, a signal for governing traffic through said stretch, coding means effective when set into operation to supply interrupted alternating current to the rails of the stretch and means effective when a train enters said stretch provided said signal is in a predetermined position to set said coding meansinto operation.

4. In combination, a stretch of railway track, a signal for governing traffic through said stretch, coding means effective when set into operation to supply interrupted alternating current to the rails ofthe stretch, so that the rails are supplied with such current for different proportions of a given interval of time depending upon'trafiic conditions in advance of thestretch, and means effective when a train enters said stretch provided said signal is in a predeterminedposition;to set said. coding means into operation.

5. In combination, a stretch of railway track, a signal for governing trafiic through said Stretch, a switch in said stretch, coding meanscontrolled in accordance with theposition of said switch and effective when setinto operation to supply interrupted alternating current to the rails of the stretch, andmeans effective when atrainenterssaidstretch provided said signal is ina;predetermined positiont-o set said coding means into operation.

6. In combination, a stretch of ;railway track, a switch in said stretch,;a codingde, vice operated when a train enters the stretch, and means controlled by said switch and by saidcoding device for at timessupplyingthe rails of the stretch with periodically interrupted alternating current.

'2'. In combination, a stretch of railway track, a switch in said stretch, means icontrolled in accordance with the position of said switch for supplying alternating curs rent to the rails of said stretch, and means controlled by trafiic conditions for at times periodically interrupting said current.

8. In combination, a stretch .of railway track, a switch in said stretch, means effective when said switch is in one position to supply interrupted alternating currentto the stretch sothat current flows in the rails for one proportion given interva'lof time, and means effective when said switch is in a different position to supply the rails with interrupted alternating current so that current- :flows in the rails for said one proportion or a different proportion of said time interval depending upon traffic conditions.

9. In combination, a stretch of railway track, a switch in said stretch,-two contacts arranged at times to operate intermittently so that the contacts are closed for different proportions of agiven interval of time, means effective when said switch is in .one position to supply current to the rails of-said stretch over one or the other of said contacts dependmg upon traflic condltlons, and means eifective when said switch occupies other positions to supply current to the rails over the remaining contact only. I

10. In combination, a stretch of railway track, a track relay connected with the rails of the stretch, a signal for governing traliic through the stretch, a stick relay controlled by said track relay and said signal, a coding device controlled by said stick relay, means for supplying alternating current to the rails of the stretch, and means controlled by said coding device for at times periodically interrupting the supply of such current.

11. In combination, a stretch of railway track, a track relay connected with the rails of the stretch, a signal for governing traiiic through the stretch, a stick relay, means for energizing said stick relay if said track relay becomes de-energized while said signal displays a predetermined indication, means for subsequently maintaining said stick relay in its energized condition as long as said track relay remains de-energized, a coding device controlled by said stick relay, and means controlled by said coding device for supplying interrupted alternating current to the rails of the stretch.

12. In combination, a section of railway track, containing a switch, and means for supplying the rails of said section with train governing current periodically interrupted in accordance with one code or another depending on trafiic conditions in advance of the section when said switch is in normal position, and for supplying said rails with train governing current periodically interrupted in accordance with only one of said codes regardless of trahic conditions in advance of the section when said switch is in the reverse position.

13. In combination, a section of railway track, containing a switch, and means for supplying the rails of said section with train governing current periodically interrupted in accordance with a proceed code or a caution code depending on traffic conditions in advance of the section when said switch is in the normal position, and for supplying said rails with train governing current periodically interrupted in accordance with the caution code only regardless of trafic conditions in advance of the section when said switch is in the reverse position. i

14:. In combination, a section of railway track containing a switch, a source of alternating current, an electric motor, and means controlled by said motor for periodically conconditions in advanve of the section when said switch is in the reverse position.

15. In combination, a section of railway track containing a switch, a coding device comprising a motor and two contacts operated by said motor in accordance with two difierent codes, a source of alternating current, and means for connecting said source with the rails of said section through one or the other of said contacts according to traiiic conditions in advance of the section when said switch is in the normal position, and for connecting said source with the rails of the section through one of said contacts but not the other regardless of trafiic conditions in advance of the section when said switch is in the reverse position.

In testimony whereof I affix my signature.

HERBERT A. WALLACE.

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