US2168817A

US2168817A - Railway signaling

Info

Publication number: US2168817A
Application number: US74257A
Authority: US
Inventors: George R Pflasterer
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1936-04-14
Filing date: 1936-04-14
Publication date: 1939-08-08
Anticipated expiration: 1956-08-08

Description

Aug 8, 1939- G. R. PFLASTERER 2,168,817

v v RAILWAY SIGNALING Filed April 14, 1956 2 Sheets-Sheetl l INVENTOR Georgellar'zemn m BYQ/KM H15 ATTORN EY Aug. 8; 1939.

G. R. PFLASTERER 2,168,817

RAILWAY SIGNALING 2 Sheets-Sheet 2 Filed April 14, 1936 Rezzwd Palapized elayf.

c' Y* l? 5TH 6TH L HIS ATTORNEY Patented Aug. 8, 1939 RAILWAY SIGNALING.

George R. Pllasterer, Swissvale,.Pa., assigner to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania e Application Api-i1 14, 193e, serial No'. 74,257

25 Claims.

My invention relates to railway signaling, and particularly to signaling involving wayside signals for stretches of. single track over which traffic moves in both directions.

5 A feature of my invention is the provision of novel and improved apparatus whereby, when the stretch is occupied by a train, the signals governing trafc following such train willprovide a three-block, four-indication, system of signaling but whereby the signals governing trailic opposing suchtrain will all display the stop indication.

The apparatus provided by this invention is an improvement on that shown and claimed in an application of Henry S. Young, Serial No.

66,002, filed February 27, 1936, for Railway signaling.

I will describe one form of apparatus embodying my invention, and will then point out th novel features thereof in claims.

In the accompanying drawings, Figs. 1A and 1B are diagrammatic views which, when placed end to end in the order named, illustrate `oneform of railway signaling system embodying my invention. f

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

Referring tothe drawings, the reference characters 'I and 8 designate the rails of a stretch of railway track over which traic normally moves in both directions, which track is provided with two passing sidings PI and P2. The stretch of track between these two sidings is divided by means of insulated joints 9 into a plurality of successive track sections W'-X, X-Y, and YZ.

As here shown, each track `section is divided into at least two subsections IT, 2T, 3T, 4T, etc.

Each subsection is provided with a track circuit comprising a track battery I0 connected across the rails at one end of the subsection, and a track relay, designated by the reference character TR with a prex the same as the numerical prefix in the reference character of the associated subsection, connected across the rails adjacent the otherend of the subsection.`

Eastbound traffic, that is, vtrailicv frornleft to right overvthe stretch of track shown inthe drawings, is controlled by trackway signals II,

I3, I5, and Il, located at points W, X, Y, and Z,

respectively. I shall termthe signals II and I 'I headblock signals and the signals I 3 and I 5 intermediate signals.y y y Y These signals each comprise an upper unit and a lower unit L. As here shown, each `upper unit U includes a red and yellow as Well as a green lamp and each lower unit L includes a single yellow lamp. i

Each signal is controlled by a polarized direct current relay and by a neutral direct current relay designated by the reference characters H 5 and J, respectively, each with a prefix the same as the reference character of the associated signal.

Each relay H is directly connected to a pair of li-ne conductors each of which extends to the l0 signal next in advance v'and each of which includes a front contact of each of the associated track relays. i

-E-ach relay J- is directly connected to the output terminals of an asymmetricunit designated 15 by the reference character Q with a prefix the same -as the reference character of the associated signal.

The input terminals of each asymmetric unit Q are connected, by means of front neutral contacts 20 of-the associated relay H, to the same pair of conductors to which ytherelay H is connected, and are connected by means of back neutral contacts of the associated relay H, to the pair of conductors through a transformer and resistor designated by the reference characters M and F, respectively, each with a prefix the same as the reference character of the associated signal.

It will be seen, therefore, that when the relays H are energized, the associated relay J `also will be energized butthat the` relays J may beenergized independently ofthe energization of the associated relay H.

As will be explained more in detail hereinafter, each pair of Aconductors is at times supplied with 35 direct current and at other times supplied with alternating current. i The high impedance of the direct current relays H will prevent the iiow of alternating current in these relays so that ythe relays H will not respond when the line con- 40 ductors are supplied with alternating current. The resistors F will prevent theexcessive flow of direct current in the primary windings of the transformers M.

Associated with each intermediate signal and 45 controlled by the associated relay J, as well as thetrack relay for the subsection immediately in advance of the signal, is a. directional stick relay designated by the reference character S` with a prefix the same as the reference character of 50 the. associated signal. i

yThe relays H, J, and S control the energy supplied to the line conductors for the control of the relays H and` J associated with the signal next in rear in such a manner that such conductors will be supplied with direct current of normal polarity or with direct current of reverse polarity or with alternating current or with no current, depending upon traffic conditions in advance.

Associated with each signal is a suitable source of direct current, the terminals of which are designated by the reference characters B and C.

Each signal is provided With a transformer, designated by the reference character N with a prefix the same as the reference character of the associated signal. a primary Winding I9 and a secondary Winding 20. The secondary Winding 20 is at times connected to the line conductors extending in rear of the signal with which such transformer is associated so that, when alternating current is supplied to primary Winding I9, the relay J for the signal next in rear will become energized.

For supplying alternating current to the primary winding I9 of the transformers N, each signal is provided with a device for converting direct current into alternating current and designated by the reference character A with a prefix the same as the reference character of the associated signal. As here shown, each device A is the well-known tuned reed alternator. Referring to alternator I3A, for example, the reference character 2| designates a reed which is caused to vibrate between terminals 22 and 23 by a control winding 24. In the deenergized condition, reed 2| does not connect with either terminal 22 or terminal 23 but does connect with a terminal 25. When, energy is supplied to alternator |3A, winding 24 will attract reed 2| causing it to connect with terminal 23 and to move away from terminal 25causing winding 24 to become deenergized. Upon the deenergization of winding 24, lthe resilience ofreed 2| will cause it to move away from terminal 23 and to connect with terminal 22 as Well as with terminal 25. The circuit for winding 24 will then be completed so that reed 2| againwill go through the cycle of operationjust described. Winding 24, therefore, will be repeatedly energized and deenergized as long as energy is supplied to its control circuit. When reed 2| connects with terminal 23, current will be supplied vto the right-hand portion of primary windingIS of transformer |3N, and when reed 2| connects with terminal 22, current will then be supplied in the opposite direction to the lefthand portion of primary winding I9. Alternating current, therefore, will be induced in secondary winding 20 of transformer I3N as long as alternator |3A is operating.

The alternator A for each of the other signals functions to supply alternating current to the associated transformer N in a manner similar to that described for alternator |3A.

Under normal conditions, that is, With the stretch unoccupied, each relay H is energized in the normal direction and, therefore, each relay J also is energized. Relay I IH, for example, is energized in the normal direction by a circuit which passes over a path from terminal B of the direct current source at signal I3. through front point of contact 26 of relay |3H, front contact 21 of relay ZTR, front contact 28 of relay ITR, relay IIH, front contact 29 of relay ITR, front contact 30 of relay 2TR, and front point of contact 3| of relay |3H to terminal C of the same source of energy. Relay IIJ also is energized over a circuit which passes over the same path as just described for relay IIH except that front points of

contacts

32 and 33 of relay IIH and relay IIJ are substituted for relay I IH.

Each transformer N includes When the relays H are energized in the normal direction and the associated relay J also is energized, the green lamp G of the upper unit U of the associated signal is energized to cause the display of a green light to indicate proceed at normal speed. For example, the green lamp G of the upper unit U of signal is energized by a circuit which passes over a path from terminal B through front point of contact 34 of relay I IJ, front contact 35 of relay IIH, normal polar contact 36-31 of relay IIH, and lamp G to terminal C.

Each signal, therefore, under normal conditions, has its control relays H and J energized in such a manner as to cause the signal to display the normal proceed indication.

I shall now assume that an eastbound train, that is, a train traveling from left to right, enters section W-X so that relay ITR becomes released to cause the deenergization oi relays IIH and IIJ.

When relay IIJ becomes deenergized, the red lamp R of the upper unit U of signal Will be energized by a circuit which passes over a path from terminal VB through back point of contact 34 of relay IIJ and lamp R to terminal C. Signal II, therefore, will display a red light to indicate stop.

When the train enters section X-Y so that relay 3TR becomes released, relays |3H and |3J will become deenergized. Relay |3J, however, due to its slow releasing characteristic, will not release immediately. In the meantime, a pickup circuit will be established for directional stick relay |3S. This circuit maybe traced from terminal B through back contact 40 of relay 3TR, front point of contact 4| of relay |3J, and relay |3S to terminal C. When relay I3S becomes picked up, a stick circuit will be closed over a path which passes from terminal B through back contact 40 of relay STR, front contact 42 of relay |3S, and relay I3S to terminal C. When relay |3J does become released, a second stick circuit will be established so that relay I3S will be maintained in its picked up condition as long as relay I3J remains in its released condition, that is, as long as the train occupies section X-Y. The second stick circuit passes over a path from terminal B through back point of contact 4| of relay |3J, front contact 42 of relay S, and relay I3S to terminal C.

When relay I3S is picked up, alternator I3A will be energized over front contact 43 of relay |3S so that-alternating current energy will be induced in secondary winding 20 of transformer When both relays I3J and I3H are released and relay |3S is picked up, signal I3, of course, will indicate stop, and the line conductors for the section W-X will be supplied with alternating current so that primary winding 44 of transformer IIM will become energized when the train vacates section W-X. The circuit for transformer IM passes over a path from one terminal of secondary winding 20 of transformer IBN through front contact 45 of relay |3S, back point of contact 46 of relay |3J, back point of contact 26 of relay I 3H, front contact 21 of relay 2TR, front contact 28 of relay ITR, primary winding 44, resistor IIF, front contact 29 of relay ITR, front contact 30 of relay 2TR, back point of contact 3| of. relay ISH, back point of contact 4l of relay |3J, and front contact 48 of relay |3S to the other terminal of secondary winding 20 of trnsformer |3N. When primary Winding 44 of rent, current will be induced in secondary wind-y ing 49 so that relay IIJ will become energized over' anl easily traced circuit which includes the

back pointsof contacts

32 and 33 of relay II H.

When relay IIJ is energized and relay IIH is deenergized; the yellow lamp Y of the upper unit U of signal II will be energized so that that signal Will display a single yellow light to indicatefapproach nextvsignal prepared to stop. The circuit for lamp Y may be traced from terminal B through `front 'point of contact 34 of relay. I IJ backpoint of contact 50 of relay II and lamp'Yto terminal C,

When the train departs from section X-Y and enters section Y'-'Z, both relays I5H and I5J will become deenergized and relay I5S will become energized. Signal I5, therefore, will indicate stop and the line conductors for the section X-Y will be supplied with alternating current by alternator I5A in a manner similar to that just described for section W--X so that relay I 3J will become energized to cause signal I3 to display a single yellow light to indicate approach next signal prepared to stop.

When relay I3J becomes energized, relay I 3S will become released so that energy will be disconnected from alternator I3A, and the line conductors for the section W-X Will be supplied with direct current in the reverse direction so that relay I IH will become energized in that direction. The circuit for relay IIH may be traced from terminal Bat signal I3, through front point of contact 41 of Vrelay I3J, back point of contact 3l I of relay I3H, front contact 30 of relay ZTR, front contact y29 voi relayr I TR, relay II H, frontcontact 28 of relay ITR, front contact 2'I of relay 2TH, back point of contact 26 of relay I3H, and front point of contact 46 of relay I3J to terminal C.

With relay IIH energized inthe reverse direction, relay IIJ also will become energized over iront points of

contacts

32 and 33 of relay IIH, so that the yellow lamps Y of both the upper and .lower units of signal II will be energized to r` cause signal II to display a yellow light above a yellow light to indicate -approach next signal at medium speed. The circuit.- for the lamp Y of the upper unit U of signal I I may be traced from terminal'B through front point of contact 34 of relay IIJ, front point of contact 5U of relay I IH, reverse polar contactI-SZ of relay IIH, and .lamp Y to terminal C; andthe circuit for the lamp Y ofthe lowervunit L may be traced from terminal B through front point of'contact 34 of relay IIJ, front contact of relay III-I, reverse polar contact SI5-53 of relay IIH, and lamp Y to terminal C.

When the train departs from section Y--Z and enters the section immediately to the right of location Z, both relays I'IH and I'IJ will become deenergized.` Signal I'I, therefore, will indicate stop, alternator I'IA will be energized overthe back contact '54 of relay I 'IJ, and the'line conductors for the section Y-Z will be supplied with alternating current4 energy so that relay I5J will he energized over an easily traced circuit to cause signal I5 to display a single yellow light to indicate approach next signal prepared to stop.

When relay I5J becomes energized, relay IES will become released and relay I 3H will become energized in the reverse direction over Va circuit similar to that described for the reverse energization o1" relay IIHA so that signal I3 will'be causedto display a yellow light above a yellow light to indicate approach 'next signal at medium When relay I3H is energized, relay II H will be energized in the normal direction over the previously traced normal circuit, and relay I IJ, similarly,-will be'energized over its previously traced normal circuit. y

' When relay II is energized in the normal direction, relay yI IJ also will be energized so that the green lamp `Gr of signal II will be energized over its previously traced circuit to ycause signal II to display the normal proceed indication.

Summing up thus far, it will be seen that when an eastboundv train that has passed through the stretch occupies the section to the right of .location signal I1 will display a red light to indi,- cate stop and the line conductors for the section Y-Z will be supplied with alternating current, signal I 5 will display a yellow light to indicate approach next signal prepared to stop and the line conductors for the section X-Y will be suppliedwith direct current in the reverse direction, signal I3 Will display a yellow light above a yellow light to indicate approach next signal at medium speed and the line conductors for the section W-X will `be supplied with direct current in the normal direction, and signal II will display a green light to indicate proceed at normal speed.

l It will be noted that relays H are provided with a retained neutral characteristic, that is, the front neutral contacts of these relays do not open during pole changing periods. This feature prevents tumble-down of the signal circuits tothe rearduring these periods." For example, when the train vacates the section to the right of location Z and haspassed a predetermined'point (not shown) inadvance of the other end of the passingsi'ding P2, relay I3H, which has previously been energized in the reverse direction, will then become energized in the normal direction to cause signal I3 to then display the normal proceed indication. Since, however, the front points of contacts v26 and 3| of relay- I3H do not become open during such pole changing periods, the energization of the line circuit for the section W-X will not be disturbed. l v

It will be noted also that the relays J 'are pro# vided with a slow releasing characteristic so that these relays will not become released during the time their controly circuits are beingtransferred from the back points to the front points'of the associated relay H, ,This feature prevents a momentary flash of the Vred lamp of the associated signal since such lamps are controlled by a back contact Vof the relays J and will become energized Whenever the associated relay J is released.

With all the signals and associated apparatus in the normal condition as shown in the drawings, I shall next assume that a westbound train, that is, a train moving from right to left enters section Y-Z so that relay STR becomes released to open the control circuits for the relays ISH and I5J. With both relaysv ISH and 'I5J released, signal I5 will indicate stop and the line circuits for the section vX`Y will become deenergized to cause bothrelays, I 3H and Y`I3Jfto become deenergized.A With both relays I3H and I3J deenergized, signal I3 will indicate stop and the line circuits for `the section W-X will become deenergized to cause bothrelays IIH and IIJ to become deenergized so that signal II will indicate stop. It will be seen, therefore, that all signals governing movements towards the Westbound train will indicate stop. The directional stick relays IS and IBS cannot become picked up as the westbound train proceeds through the stretch since pickup circuits for the directional stick relays can become closed only if the associated relay J is picked up.

For governing westbound movements in the stretch between the passing sidings PI and P2 I provide headblock signals I2 and I8 and intermediate signals I4 and I6. Although, in order to simplify the drawings, I have not shown full and complete circuits and control apparatus for the westbound signals, it is understood that these signals and associated apparatus will function in all respects in a manner similar to that described for the eastbound signals. In connecting up the westbound signals, only one additional line conductor will be required since one line conductor of the pair for eastbound signals may be used as a common conductor for both eastbound and westbound Signals.

In order to illustrate how one alternator A and associated transformer N may be utilized for each pair of signals, I have shown the directional stick relays I4S and IBS for the intermediate signals I4 and I6, respectively, and the signal control relays I2J and I8J lor the headblock signals I2 and I8, respectively. For example, it will be apparent that alternator I3A may be energized either over front contact 43 of relay I3S or front contact 55 of relay I4S. It will also be apparent that when relay I4S is energized so that its

front contacts

55, 5S, and 51 are closed, alternating current may be supplied to wires 58 and 59, which are here shown as a portion of the conductors extending to the rear of signal I4 for the control of signal I6.

In a similar manner, it will be obvious how alternating current may be supplied to the conductors extending to the rear of the headblock signals. For example, when relay IBJ is deenergized so that

back contacts

60, 6I, and 62 are closed, alternator IIA will become energized so that

wires

63 and 64, which are here shown as a portion of the conductors extending to the rear of signal I8, will be supplied with alternating current.

Although I have shown only two pairs of intermediate signals located between the ends of the passing sidings, it is understood that more or less than two pairs of intermediate signals may be provided if desired. Furthermore, each pair of signals may be staggered or may be located directly opposite one another as shown in the drawings.

From the foregoing -description of the apparatus embodying my invention, it is apparent that I have provided a three-block, four-indication, system of absolute permissive block signaling wherein only three line conductors are required and wherein, although alternating current is required, no commercial source of alternating current need be available. My system is economical in current consumption for the operation of the alternators A, since these alternators are required to operate only when the stretch is occupied by a train.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track provided with a track circuit including a track relay, a polarized relay for said section, means governed by traffic conditions in advance of said section for reversibly energizing said polarized relay, a neutral relay for said section which becomes energized whenever said polarized relay is energized, means governed by other tranic conditions in advance of said section for energizing said neutral relay independently of the energization of said polarized relay, a directional relay for said section governed by said neutral relay and by said track relay, and a signal control circuit governed by saiddirectional relay.

2. In combination, a section of railway track provided with a track circuit including a track relay, a polarized relay for said section, means governed by traflic conditions in advance of said section for reversibly energizing said polarized relay, a neutral relay for said section which becomes energized whenever said polarized relay is energized, means governed by other traffic conditions in advance of said section for energizing said neutral relay independently of the energization of said polarized relay, a normally deenergized stick relay for governing a signal control circuit, a pickup circuit for said stick rel-ay including a back contact of said track relay and a front contact of said neutral relay, a stick circuit for said stick relay including a back contact of said track relay and a front contact of said stick relay, and another stick circuit for said stick relay including its own front contact and a back contact of said neutral relay.

3. In combination, a section of railway track provided with a track circuit including a track relay, a pair of conductors each including a front contact of said track relay, means governed in accordance with traic conditions in advance of said section for supplying said pair of conductors with direct current of one polarity or with direct current of the other polarity or with alternating current, a direct current polarized relay connected to said conductors, an asymmetric unit connected directly to said conductors over front contacts of said polarized relay or connected1 through a transformer to said conductors over back contacts of said polarized relay, a direct current neutral relay connected to said asymmetric unit, and a signal for said section controlled by said polarized and neutral relays.

4. In combination, a section of railway track provided with -a track circuit including a track relay, a pair of conductors each including a front contact of said track relay, means governed in accordance with trafc conditions in advance of said section for supplying said conductors with direct current of one polarity or with direct current of the other polarity or with alternating current, a direct current polarized relay connected to said conductors, an asymmetric unit connected directly to said conductors over front contacts of said polarized relay or connected through a transformer to said conductors over back contacts of said polarized relay, a direct current relay connected to said asymmetric unit, a signal for said section including a iirst unit comprising a green and a red as well as a yellow lamp .and a second unit comprising another yellow lamp, a circuit for said green lamp including a front contact of said neutral relay as well as a front neutral and a normal polar contact both of said polarized relay, a circuit for said red lamp including a back contact of said neutral relay, a circuit for the yellow lamp of the first unit including a front contact of said neutral relay and a back contact of said polarized relay, anoth-er circuit for said yellow lamp including a front contact of said neutral relay and a front neutral as well as a reverse polar contact both of said polarized relay, and a circuit for s-aid other yellow lamp including a. front contact of said neutral relay as well as a front neutral and a reverse polar contact back of said polarized relay.

5. In combination, a forward section and a rear section of railway track, a rst relay and a second relay, means governed in accordance with traiiic conditions in advance of said forward section for energizing said rst and second relays simultaneously or for energizing said second relay only, a directional relay controlled bysaid second relay and by traflic conditions in the forward section, a circuit governed by said directional relay when both said first and said second relays are deenergized,4 another circuit governed by said second relay` when said first relay is deenergized, still another circuit controlled by said rst relay, and traiic governing means for the rear section governed by said three circuits.

6. In combination, a section of railway track, a polarized relay for said section, a neutral relay for said section, means including a directional relay controlled by traiiic conditions in advance of said section for energizing said polarized relay in the normal direction and for simultaneously energizing said n-eutral relay or for energizing said polarized relay in the reverse direction and for simultaneously energizing said neutral relay or for energizing said neutral relay only or for -deenergizing said neutral relay, and a signal for .said section controlled by said two relays and capable of displaying a stop indication when said neutral relay is deenergized or a restrictive proceed indication when said neutral relay only is energized or one or the other of two different andsuccessively less restrictive proceed indica- -tions according as said polarized relay is energized in the normal or reverse direction respectively provided said neutral relay also is energized.

7. In combination, a stretch of railway track having a forward and a rear signal associated 'therewith veach governing traffic in the same direction and each capable of assuming a condition toindicate stop, approach, approach medium, or proceed, means effective only when the forward Vsignal is in condition to indicate approach mediy-run or proceed and the stretch between said signals is unoccupied for causing the rear signal to assume the condition to indicate proceed, means effective only when the forward signal is in condition to indicate approach and the stretch between said signals is unoccupied for causing the vrear signal to assume the condition to indicate approach medium, a normally deenergized relay, means vfor energizing said relay when a train passes the forward signal provided said forward signal is then in condition to indicate-approach, approach medium or proceed, means eifective a predetermined time interval after such train passes the forward signal for causing that signal to assume the condition to indicate stop, means then effective'to hold said relay energized, and means effective only when said relay is energized and the Vstretch between said signals is unoccuzpied, for causing the rear signal to assume the ncondition to indicate approach. .17.5

3.1m A combinatio`n, a stretch of railway track fective when the stretch between said signals is 5 unoccupied for causing the rear signal to assume the condition to indicate proceed provided the forward signal is then in condition to indicate either approach medium or proceed and for causing the rear signal to assume the condition to in- 1 dicate approach medium provided the forward signal is then in condition to indicate approach, directional means which becomes energized when a train passes the forward signal provided that signal is then in condition to' indicate approach, 1 approach medium or proceed, means for causing said forward signal to assume the condition to indicate stop a predetermined time interval after such train passes the forward signal, means then effective to hold said directional means energized, and means eilective only when said directional means is energized and the stretch between said signals is unoccupied for causing the rear signal to assume the condition to indicate approach.

9. In combination, a stretch of railway track having a forward and a rear signal each governing traffic in the same direction and each capable of assuming a condition to indicate stop, approach, approach medium or proceed, a pair of conductors for the rear signal governed by traffic conditions in the stretch between said signals, means for supplying said conductors with current of one character to cause the rear signal to assume the condition to indicate proceed when the forward signal is then in condition to indicate proceed or approach medium and for supplying said conductors with current-of another character to cause the rear signal to assume the condition to indicate approach medium when the forward signal is in condition to indicateapproach, directional means which means become energized when a train passes the forward signal provided that signal is then in condition to indicate approach, approach medium or proceed, means for causing the forward signal to assume the condition to indicate stop a predetermined time interval after such train passes theforward signal, means effective thereafterto hold said directional means energized, and means effective when said directional means is energized to supply said con- 5 ductors with current of still a different character to cause the rear signal to assume the condition `to indicate approach.

10. In combination, a stretch of railway track, a pair of conductors, directional means automatically controlled by the direction of traino in said stretch, means including said directional means for successively supplying said conductors with three different forms of energy when and only when a train moves through said stretch in one 6 direction, a signal for said stretch governing traffic moving in said one direction and capable of displaying three distinctive proceed indications, and cntrol means selectively responsive to said three forms of energy for governing the three in- 6 dications of said signal.

11. In combination, a stretch of railway track, a pair of conductors, directional means automatically controlled by the direction of trafc in said stretch, means including said directional 7 means for successively supplying said pair of conductors with three different forms of current respectively when a train moves through said stretch in one direction but for disconnecting energy from said conductors when a train moves through said stretch in the opposite direction, a signal for said stretch governing trafc moving in said one direction and capable of displaying a stop indication and three successively less restrictive proceed indications, and control means selectively responsive to the deenergized condition and the three energized conditions of said pair of conductors for governing the four indications of said signal.

l2. In combination, a stretch of railway track, a pair of conductors, directional means automatically controlled by the direction of traffic in said stretch, means including said directional means for supplying said pair of conductors successively with alternating current, with direct current of one polarity and with direct current of the other polarity when a train moves through said stretch in one direction but for disconnecting energy from said conductors when a train moves through said stretch in the opposite direction, a signal for said stretch governing traiic moving in said one direction and capable oi displaying a stop indication and three successively less restrictive proceed indications, and control means selectively responsive to the deenergized condition and the three energized conditions of said pair of conductors for governing the four indications of said signal.

13. A railway signal system for a stretch of railway track over which trafc moves in either direction comprising, signals at spaced intervals along said stretch for governing the movement of trains in both directions, each said signal capable of displaying a stop indication and three successively less restrictive proceed indications, a pair of conductors for each signal, control means for each signal receiving energy from the associated conductors and capable of assuming four distinctive conditions to control the four indcations according as such conductors are deenergized or energized with three different characters of current respectively, directional means automatically controlled by the direction or traffic in said stretch, and means including said directional means effective when a train moves through said stretch in one direction to energize each pair of conductors for the signals governing trafiic in said one direction with said three different characters of current successively but for deenergizing each pair of conductors for the signals governing trac in the opposite direction.

14. In combination, a stretch of railway track over which trafiic moves in either direction, said track stretch being divided into a plurality of successive block sections each having a Signal governing movement of trains therein in one direction, each block section having associated therewith a pair of conductors and a fast acting relay governed by traiiic conditions in said section, each of said sections having associated therewith a slow acting relay energized from the conductors for such section, each of said sections having associated therewith an alternating current supply device for converting direct current into alternating current and for supplying said alternating current to a circuit through which said current may be supplied to the conductors of the adjacent block section in the rear, each of said sections having associated therewith a directional relay controlled jointly by the associated fast and slow acting relays and controlling the circuit for supplying direct current to said alternating current supply device, each of said sections having means energized from the conductors for said section and controlling the supply of direct current to the conductors of the adjacent block section in the rear, each of said block sections also having control means associated therewith and controlling the signal for such section, said control means being energized from the conductors for such section and being selectively responsive to alternating and to direct current supplied to said conductors.

15. In combination, a stretch of railway track over which trafic moves in either direction, said track stretch being divided into a plurality of successive block sections each having a signal governing movement of trains therein in one direction, each block section having associated therewith a fast acting relay governed by traffic conditions in said section and a pair of conductors governed by said fast acting relay, each oi said sections having associated therewith a slow acting relay energized from the conductors for such section, each of said sections having associated therewith an alternating current supply device for converting direct current into alternating current and for supplying said alternating current to acircuit through which said current may be supplied to the conductors of the adjacent block section in the rear, each of said sections having associated therewith a directional relay controlled jointly bythe associated fast and slow acting relays and controlling the circuit for supplying direct current to said alternating current supply device, each of said sections having means energized from the conductors for said section and controlling the supply of direct current to the conductors of the adjacent block section in the rear, each of said block sections also having control means associated therewith and controlling the signal for such section, said control means being energized from the conductors for such section and being selectively responsive to alternating and to direct current supplied to said conductors.

16. In combination, a stretch of railway track over which traic moves in either direction, said track stretch being divided into a plurality of successive block sections each having a signal governing movement of trains therein in one direction, each block section having associated therewith a pair of conductors and a fast acting relay governed by traffic conditions in said section, each of said sections having associated therewith a slow acting relay energized from the conductors for such section, each of said sections having associated therewith an alternating current supply device for converting direct current into alternating current and for supplying said alternating current to a circuit through which said current may be supplied to the conductors of the adjacent block section in the rear, each of said sections having associated therewith a directional relay controlled jointly by the associated fast and slow acting relays and controlling the circuit for supplying direct current to said alternating current supply device, said directional relay also controlling the circuit through which alternating current is supplied from said supply device to the conductors of the adjacent block section in the rear, each of said sections having means energized from the conductors for said section and controlling the supply of direct current to the conductors of the adjacent block section in the rear, each of said block sections also having control means associated therewith and controlling the signai for such section, said control means being energized from 'the conductors for such section and 'being selectively responsive Vto alternating and `having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each or" .said sections having associated therewith a rst and a second control device energized from the conductors for the section and controlling the signal forsuch section, said first controldevice being responsive to the supply of direct current to said conductors and said second control device being responsive to the supply of alternating current to said conductors, each .signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a 'circuit through which alternating current may be supplied to the conductors of the adjacent block section in the rear, each section having va directional relay controlled jointly .by the fast acting relay and one of the control devices for the signal for such section, the directional relay controlling the circuit for supplying directeurrent to the associated alternating current supply mechanism, the second control device being operative when energized to condition the signal to display a restrictive proceed indication, the rst control device being operative alone when energized to condition the signal to display its normal proceedy indication, the second control device controlling a 'circuit for supplying direct current to the conductors of the adjacent block section in the rear. f

18. In combination, a stretch of railway track over which trafiic moves in either direction, said track stretch being divided into a plurality of successive block sections each having a pair of conductors and a fast acting relay governed by traffic conditions in said section, each section having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said sections having associatedtherewith a first and a second control ,device energized from the conductors for the section and controlling the signal for such section, said iirst control device being responsive to the supply of direct current to said conductors and said second control device being responsive to the supply of alternating current to said conductors, each signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit through which alternating current may be supplied to the conductors of the adjacent block section in the rear, each section havinga directional relay controlled jointly by the fast acting relay and one of the control devices for the signal for such section, said one of the control devicesf and the directional relay jointly controlling the circuit for supplying direct current to the alternating current supply mechanism for such section, the second control device being operative when energized to condition the signal to disp-lay a restrictive proceed indication, the iirst control device being operative alone when energized to condition the signal to display its normal proceed indication, the second control device controlling a circuit for supplying direct current to the conductors of the adjacent block section in the rear.

19. In combination, a stretch of railway track over which traffic moves in either direction, said track stretch being divided into a plurality of successive block sections each havinga pair of conductors and a fast acting relay governed by traiiic conditions in said section, each section having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a rst and a second control device energized from the conductors for the section and controlling the signal for such section, said rst control device being responsive to the supply of direct current to said conductors and said second control device being responsive to the supply of alternating current to said conductors, each signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit through whichalternating current may be supplied to the conductors of the adjacent block section in the rear, each section having a directional relay controlled jointly by the fast acting relay and one of the control devices for the signal for such section, the directional relay controlling the circuit for supplying direct current to the alternating current supply mechanism for such section, said irst and second control devices and the directional relay jointly controlling the circuit for supplying direct current to the supplyk mechanism for said section, the second control device being operative when energized to condition the signal to display a restrictive proceed indication, the first control device being operative alone when energized to condition the signal-to display its normal proceed indication, the second control device controlling a circuit for supplying direct cur rent to the conductors of the adjacent block section in the rear.

20. In combination, a stretch of railway track over which traiiic moves in either direction, said track stretch being divided into two adjacent block sections including a forward and a rear block section, each of said block sections having a signal governing movement of trains therein in one direction, each Aof said block sections having a pair of kconductors governed by traic conditions in said section, means energized fronjlthe conductors of the forward block sectionforcontrolling the signal for such section and forcontrolling a circuit through which direct current may be supplied to the conductors of the rear block section, the forward section having associated therewith a fast acting relay governed by traic conditions in said forwardA section and a slow acting relay energized from the conductors for such section, the forwardA section also having associated therewith an alternating current, supply device for converting direct current into alternating current and for supplying such alternating current to a circuit through which current may be supplied to the conductors of the rear block section, said forward block section having associated therewith a directional relay controlled jointly by said fast and slow acting relays and controlling the circuit for supplying direct current to said supply device, and means selectively responsive to alternating and direct current supplied to the conductors of the rear section for governing the signal for said rear section.

21. In combination, a stretch of railway track over which traic moves in either direction, said track stretch being divided into a plurality of successive block sections each having a signal governing movement of trains therein in one direction, each of said block sections having a pair of conductors and a fast acting relay governed by traflic conditions in said section, each of said block sections having a pair of control relays energized from the conductors for such section and controlling the signal for such sect1-on, one of said relays being responsive to direct current supplied to said conductors, the other of said relays being responsive to alternating current supplied to said conductors, one of said relays being slow acting, each of said block sections having associated therewith an alternating current supply device for converting direct current into alternating current and for supplying such current to a circuit through which current may be supplied to the conductors of the adjacent block section in the rear, each of said block sections having associated therewith a directional relay controlled jointly by the associated fast acting relay and the slow acting one of the control relays, said directional relay controlling the supply of direct current to the supply device for such block section, and means controlled by one of the control relays for each block section for supplying direct current to the conductors of the adjacent block section in the rear.

22. In combination, a stretch of railway track over which traflic moves in either direction, said track stretch being divided into a plurality of successive block sections each having a signal governing movement of trains therein in one direction, each of said block sections having a pair of conductors and a fast acting relay governed by trafc conditions in said section, each of said block sections having a pair of control relays energized from the conductors for such section and controlling the signal for such section, one of said relays being responsive to direct current supplied to said conductors, the other of said relays being responsive to alternating current supplied to said conductors, one of said relays being slow acting, each of said block sections having associated therewith an alternating current supply device for converting direct current into alternating current and for supplying such current to a circuit through which current may be supplied to the conductors of the adjacent block section in the rear, each of said block sections having associated therewith a directional relay controlled jointly by the associated fast acting relay and the slow acting one of the control relays, said directional relay controlling the supply of direct current to the supply device for such block section, and means controlled by both of the control relays for each block section for supplying direct current to the conductors of the adjacent block section in the rear.

23. In combination, a stretch of railway track over which traiiic moves in either direction, said track stretch being divided into a plurality of successive block sections each having a signal governing movement of trains therein in one direction, each of said block sections having a pair of conductors and a fast acting relay governed by traic conditions in said section, each of said block sections having a pair of control relays energized from the conductors for such section and controlling the signal for such section, one of said relays being responsive to direct current supplied to said conductors, said relay being selectively responsive to the polarity of the current supplied thereto, the other of said relays being responsive to alternating current supplied to said conductors, one of said relays being slow acting, each of said block sections having associated therewith an alternating current supply device for converting direct current into alternating current and for supplying such current to a circuit through which current may be supplied to the conductors of the adjacent block section in the rear, each of said block sections having associated therewith a directional relay controlled jointly by the associated fast acting relay and the slow acting one of the control relays, said directional relay controlling the supply of direct current to the supply device for such block section, and means controlled by both of said control relays for each block section for selectively supplying direct current oi one polarity or the other to the conductors of the adjacent block section in the rear.

24. In combination, a section of railway track provided with a pair of conductors and a fast acting relay governed by trac conditions in said section, means governed by traic conditions in advance of said section for supplying direct and alternating current to said conductors, a first and a second control relay for said section energized from said conductors, said rst control relay being energized whenever said conductors are energized with direct current, said second control relay being energized whenever said conductors are energized with alternating current and whenever said rst control relay is energized, one of said control relays being slow acting, adirectional relay controlled jointly by said fast acting relay and the slow acting one of the control relays, and a signal control circuit controlled by said directional relay.

25. In combination, a section of railway track provided with a pair of conductors and a fast acting relay governed by traflic conditions in said section, means governed by traic conditions in advance of said section for supplying direct and alternating current to said conductors, a nrst and a second control relay energized from said conductors, said first control relay being responsive to the supply of direct current to said conductors, said second control relay being responsive to the supply of alternating current to said conductors, one of said relays being slow acting, a directional relay controlled jointly by said fast acting relay and the slow acting one of said control relays, and a signal control circuit controlled by said directional relay.

GEORGE R. PFLASTERER.