US2168816A - Railway signaling - Google Patents

Description

Aug. 8, 1939 H. a um 2,168,816

RAILWAY S IGNALING Original Filed Feb. 27, 1936 3 Sheets-Sheet i dlDR CL l 5mg INVENTOR Henry S. Ybung HIS ATTORNEY Aug. 8, 1939- H s, YOUNG 2,168,816

RAILWAY S IGNALING 'ori inal Filed Feb. 27, 1936 3 Sheets-Sheet 2 INVENTOR Henry S. l/oulzy.

HIS ATI'ORNEY g- 1939 H. s. YOUNG ,16

RAILWAY SIGNALING Original Filed Feb. 27, 1936 3 Sheets-Sheet s INVENTOR Henry S. Ybuzzy.

HIS ATTQRNEY Patented Aug. 8, 1939 UNITED STATES PA'E'NT GEHQE.

RAILWAY SIGNALING Application February 27, 1936, Serial No. 66,002 Renewed May 28, 1938 22 Claims.

My invention relates to railway signaling, and particularly to signaling involving wayside signals located along a trackway for governing the passage of trains.

A feature of my invention is the provision of novel and improved apparatus which requires but two line control wires or conductors for establishing a distinctive control for each of three sections in the rear of an occupied section. Each distinctive control is effective to cause a corresponding aspect of the associated wayside signal, whereby there is produced a three-block, fourindication, system of signaling. Another feature of my invention is the provision of apparatus, utilizing asymmetric units, for controlling wayside signals in such a manner as to prevent the display of a less restrictive indication in the event such asymmetric units fail to function properly.

I will describe several forms of apparatus embodying my invention, and will then point out the 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 one form of apparatus embodying my invention. Figs. 2 and 3 are diagrammatic views illustrating modifications of a portion of the apparatus shown in Fig. A and each also embodying my inven- 30' tion.

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

Referring first to Figs. 1A and 1B, the reference characters 8 and 9 designate the rails of a stretch of railway track along which traffic normally moves in the direction indicated by the arrows. These rails are divided by insulated joints 14 into a plurality of track sections or blocks W-X, XY, and Y-Z.

Each track section is divided by insulated joints l4 into at least two subsections IT, 2T, 3T, tT, etc. Each subsection is provided with a track circuit which includes a track battery 15 connected across the rails at one end of the sub- 45 section and a track relay, designated by the reference character TR with a prefix the same as the numerical prefix in the reference character of the associated subsection, connected across the rails at the other end of the subsection.

To govern the passage of trains through the stretch of railway, a wayside signal, designated by the reference character S with a suitable distinguishing prefix, is provided for each track section. Each of these signals comprises a top unit T and a lower unit L, These units may take any one of several forms of signal mechanisms such as searchlight, semaphore, color light, or position light. As here shown, each top unit is a color light signal comprising a green, a yellow, and a red lamp; and each lower unit is a color light signal comprising a green and a red lamp.

Each signal is provided with a pair of polarized line control relays designated by the reference characters HR and DR, respectively, each with a prefix the same as the prefix in the reference character of the associated signal.

The relays HR and DR of each signal are connected across the conductors of a two-wire line circuit extending to the signal next in advance. Each relay HR is provided with a shunt including an asymmetric unit A2, while each relay DR is provided with a shunt including an asymmetric unit A3. The units A2 and A3 are oppositely disposed so that current of one polarity but not the other is forced to flow through relay HR, while current of the second polarity but not the first is forced to flow through relay DR. In the arrangement shown herein, relay HR is provided with an additional asymmetric unit A which freely passes the current which is forced by unit A2 to flow through relay HR, but opposes the passage of the flow of current of the other polarity in relay HR. Relay DR is similarly provided with an additional unit Al which freely passes current that is forced by unit A3 to fiow through the relay DR, but opposes the passage of current of the other polarity.

Each signal is provided with a device, designated by the reference character CT with a prefix the same as the prefix in the reference character of the associated signal, for converting into alternating current direct current supplied from a customary source. The devices CT are here shown diagrammatically and may be the wellknown current coding relays. Since the particular form of coding relay is not involved in my invention, it will be sufiicient to state that each relay CT, when energized, is caused to move its contacts between the front and back points a fixed and definite number of times per minute. Each coding relay has its contacts connected, in the form of a pole changer, to the terminals B and C of the source of direct current at the associated signal so that when the coding relay is operating, the line circuit for the signal next in rear may be supplied with alternating current having a definite frequency. Each coding relay CT is controlled by the relays HR and DR of the associated signal in such a manner that the alternator or coding relay operates only when the associated signal is displaying the two less re strictive indications, that is, when the signal is displaying the proceed at normal speed indication, or the approach next signal at medium Speed indication.

Each signal is provided with a transfer relay designated by the reference character PC with a prefix the same as the prefix in the reference character of the associated signal. Each relay PC is controlled by the associated HR and DR relays and connects the line circuit for the signal next in rear, either with the pole-changing contacts of the associated coding relay CT to supply alternating current to that line circuit, or with contacts of the associated HR and DR relays to supply direct current to that line circuit.

Each of the color light signals herein shown is controlled by the associated relays HR and DR in the following manner: When both relays are deenergized (see signal I3S), the red lamp R of the top unit T is lighted by a circuit which passes from terminal B of a suitable source of direct current energy through back point of contact I6 of relay ISDR, back point I! of relay IEHR, and lamp R to terminal C of the same source of energy; and the red lamp R of the lower unit L is lighted by a circuit which passes from terminal B through back point of contact I8 of relay I3DR and lamp R to terminal C. Signal I3S, therefore, displays a red light over a red light to indicate stop. When relay HR is energized and relay DR is deenergized (see signal IZS), the yellow lamp Y of the top unit T is lighted by a circuit which passes from terminal B through back point of contact I9 of relay IZDR, front point of contact 2!! of relay IZHR, and lamp Y to terminal C; the red lamp R of the lower unit L is lighted by a circuit which passes from terminal B over back point of contact 2i of relay I2DR and lamp R to terminal C. Signal IES, therefore, displays a yellow light above a red light to indicate approach next signal prepared to stop. When relay HR is deenergized and relay DR is energized (see signal IIS), the yellow lamp Y of the top unit T is lighted by a circuit which passes from terminal B through front point of contact 22 of relay I IDR, normal polar contact 23-44 of relay IIDR, back point of contact 25 of relay I !HR, and lamp Y to terminal C; and the green lamp G of the lower unit L is lighted by a circuit which passes from terminal B through front point of contact 25 of relay IIDR, normal polar contact 2'IZ8 of relay I IDR, back point of contact 29 of relay I IHR, and lamp G to terminal 0. Signal IIS, therefore, displays a yellow light above a green light to indicate approach next signal at medium speed. When both relays HR and DR are energized (see signal IGS), the green lamp G of the top unit T is lighted by a circuit which passes from terminal B through front point of contact 3I of relay IUDR, normal polar contact 32-33 of relay IODR, front point of contact 34 of relay lBHR, normal polar contact 35-36 of relay IGHR, and lamp G to terminal C; and the red lamp R of the lower unit L is lighted by a circuit which passes from terminal B through front point of contact 31 of relay IEIDR, normal polar contact 38-39 of relay IBDR, front point of contact 40 of relay IOHR, and lamp R to terminal C. Signal IDS, therefore, displays a green light over a red light to indicate proceed at normal speed.

As shown in the drawings, the section immediately to the right of point Z is occupied by a train K, so that the line circuit for that section is opened with the result both relays I3HR and I3DR are deenergized.

When both relays I3HR and I3DR are deenergize d, relay I2HR is energized by direct current of one relative polarity over a circuit which passes from terminal B, at signal I38, through back point of contact 42 of relay I3DR, back point of contact 43 of relay I3HR, back point of contact 44 of relay I3PC, front contact 45 of track relay BTR, front contact 45 of track relay 5TR, asymmetric unit A3, relay IZHR, asymmetric unit A, front contact 4? of track relay 5T, front contact 48 of track relay GTR, back point of contact 49 of relay I3PC, back point of contact 50 of relay ISHR, and back point of contact 5! of relay I3DR to terminal C.

When the line wires are energized with current of this relative polarity the relay IZDR is not energized since the asymmetric unit AI prevents flow of current of this relative polarity in the winding of the relay lZDR. The contacts of relay IZDR, therefore, remain released.

When relay IZHR is energized and relay IZDR is deenergized by current of the opposite relative polarity, relay iI DR is energized over a circuit which passes from terminal B at signal I2 through front point of contact 53 of relay IZHR, back point of contact 54 of relay IZPC, front contact 55 of relay lTR, front contact 56 of relay 3TB, asymmetric unit A2, relay IIDR, asymmetric unit AI, front contact 51 of relay 3TR, front contact 58 of relay 4TR, back point of contact 59 of relay I2PC, and front point of contact 69 of relay I ZHR to terminal C.

When the line wires are energized with current of this relative polarity the relay III-IR is not energized since the asymmetric unit A prevents flow of current of this relative polarity in the winding of the relay. The contacts of the relay I IHR, therefore, remain released.

When relay I IHR is deenergized and relay I IDR is energized, both relays IIPC and IICT are en ergized over a circuit which passes from terminal B through normal polar contact 63-64 of relay IIDR, front contact 55 of relay I I DR, back point of contact 66 of relay I EHR, and thence over two paths, one of which passes through transfer relay IIPC to terminal C and the other of which passes through coding relay II CT to terminal C. When both relays IIPC and II CT are energized, both relays IBI-IR and IQDR are energized by alternating current supplied over the line circuit for section WX. That is, this line circuit is connected by front contacts 68 and 69 of relay IIPC to contacts 15 and H of coding relay IICT so that the line circuit is alternately supplied with current of one polarity and then the other polarity.

When the line wires of the section W--X are supplied with current of one relative polarity, by the coding relay I ICT, the winding of relay IllHR is energized, while the asymmetric unit AI prevents fiow of this current in the winding of relay HlDR. Similarly when the line wires are supplied with current of the other relative polarity the winding of the relay IllDR is energized, while the asymmetric unit A prevents flow of this current in the winding of the relay IOHR.

On subsequent reversal of the polarity of the current supplied by the coding relay I I CT to the line wires of the section WX, the winding of relay IElHR is again energized, while the winding of relay IUDR is no longer energized,

The contacts of the relays IOHR and IDDR do not release instantaneously on the interruption of the supply of current to the windings of these relays, and the reversals in the polarity of the current supplied by the coding relay l ICT are so rapid that the relays IUHR and IODR bridge over the periods in which their windings are not energized, with the result that when the line wires are supplied with alternating current by the coding relay IICT, the contacts of the relays [DI-1R and IUDR. are maintained picked up.

When both relays llll-IR and IUDR are energized, transfer relay lllPC and coding relay IOCT are both energized so that the line circuit for the signal (not shown) next in rear of signal "is is supplied with alternating current to provide a proceed indication at that signal. The circuit for the energization of relay IOPC and relay IOCT may be traced from terminal B through normal polar contacts 1213 of relay IDDR, front contact 14 of relay IUDR, normal polar contact 15l6 of relay IBHR, front point of contact 11 of relay IDHR, and thence over two paths, one through relay IUPC to terminal C, and the other through relay NOT to terminal C.

It will be noted that the polar contacts of relays HR and DR do not ordinarily change their positions. That is, as long as the associated asymmetric units function properly, the relays HR, and DR will maintain their normal polar contacts closed when energized. However, if, for example, the asymmetric units at signal lZS should become deranged so that relay IZDR should become energized by the current which is energizing relay IZI-IR, the neutral contacts of relay IEHR would become picked up and the polar contacts of relay lZDR would immediately assume their reverse position since such current is of reverse polarity with respect to relay IZDR. The picking up of the neutral contacts and the reversal of the polar contacts of relay IZDR would light the yellow lamp Y of the top unit T of signal IZS by a circuit which passes from terminal B through front point of contact l9 of relay lilDR, reverse polar contact 8l!8l, and lamp Y to terminal C; and would light also the red lamp R of the lower unit L over a circuit which passes from terminal B through front point of contact 2! of relay liDR, reverse polar contact 82-83, and lamp R to terminal 0. The signal iZS, therefore, would continue to display a yellow light over a red light and would be prevented from displaying a less restrictive indication even though relays l2I-IR and IZDR. are both energized. Similarly, if the asymmetric units at signal HS should become deranged so that relay iii-IR should become energized by the current which is energizing relay HDR, the neutral contacts of relay HHR would become picked up and the polar contacts of relay HHR. would immediately reverse their position. The picking up of the neutral contacts and the reversal of the polar contacts of relay HHR would light the yellow lamp Y of the top unit T at signal HS by a circuit which passes from terminal B through front point of contact 22 of relay HDR, normal polar contact 23-44 of relay HDR, front point of contact 25 of relay Ill-IR, reverse polar contact 8485 of relay l lHR, and'lamp Y to terminal C; and the red lamp R of the lower unit L would be lighted by a circuit which passes from terminal B through front point of contact 26 of relay I IDR, normal polar contact 21-28 of relay l IDR, front point of contact 29 of relay HHR, and lamp R to terminal C. The signal HS would display a yellow light over a red light instead of a yellow light over a green light; that is, a more restrictive indication, even though relays IIHR and DR are both energized.

It will be noted that if relay III-IR should become energized by current of such polarity as is required to energize relay HDR, the circuit for the energization of relay PC and relay I ICT will become opened by the reversal of polar contact 86 of relay HHR so that the line circuit for the signal 40S will be supplied with direct current of such polarity as will pick up relay HJHR. The signal IBS, therefore, will display a more restrictive indication, that is, a yellow light over a green light instead of a green light over a red light.

Referring next to Fig. 2, the reference character P with a suitable distinguishing prefix designates an alternating current transfer relay which may be used at each signal instead of the transfer relay PC shown in Figs. 1A and 1B.

With the modification shown in Fig. 2, the coding relay CT at each signal is replaced by a source of alternating current the terminals of which are designated by the reference characters BX and CX. The source of alternating current, for example, may be any convenient commercial supply.

It will be apparent that the relays P0 operate in a manner similar to that described for the relays PC shown in Figs. 1A and 1B. That is, when the relays P0 are energized, the line circuits for the signals next in rear are supplied with alternating current and when the relays P0 are deenergized, such line circuits are supplied with direct current of one polarity or another depending upon traffic conditions in advance.

For example, at signal HS, the transfer relay HPO may be energized by a circuit which passes from terminal BX through normal polar contact 9E9l of relay HDR, front contact 92 of relay HDR, back point of contact 93 of relay HHR, and relay MP0 to terminal CX. When relay MP0 is energized, the line circuit for the control of relays lElI-IR, and IBDR is connected to alternating current by the front points of contacts 94 and 95 of relay HPO so that signal its will display the proceed at normal speed indication. When relays IOHR and IGDR are both energized, the relay lllPO is energized by a circuit which passes from terminal BX through normal polar contact 94l95 of relay HlDR, front contact 96 of relay IUDR, normal polar contact 9'l98 of relay IGHR, front point of contact 99 of relay IElHR, and relay IllPO to terminal CX. When relay [@PO is energized, the line circuit for the signal next in rear is supplied with alternating current energy overthe front points of contacts H19 and ill! of relay PO so that such signal is caused to display the proceed at normal speed indication. 1

It will be apparent that with the modification shown in Fig. 2, if the alternating current source of energy should fail, the system will continue to function as a two-block, three-indication sys-' tem, to keep traffic moving. For example, if the alternating current source should fail at signal HS, the relay HPO would become released so that direct current energy of the polarity effective to energize relay IGDR would be supplied to the line circuit for the signal l 08.

Although I have shown in Fig. 2 a portion of the apparatus associated with signals IDS and HS only, it is understood that this modification may be applied to each signal shown in Figs. 1A and 1B, and that when the system is modified as illustratcd in Fig. 2, the signaling system operates in a manner similar to that described for the system shown in Figs. 1A and 1B except where shown and described otherwise. In other words, my invention comprises a signaling system which may convert its supply of alternating current from the usual source of direct current at each signal, or which may receive its supply of alternating current from a source separate and distinct from its usual direct current source of energy.

Referring now to Fig. 3, the reference character Q designates in general an alternator which may be substituted for the current coding relay CT. As here shown, alternator Q is of the well-known tuned reed type having an elastic member I03 which is caused to vibrate between terminals I04 and I05 by a control winding I06. In the deenergized condition, member I03 does not connect with either terminal I04 or I05 but does connect with a terminal I01. When energy is supplied to alternator Q, winding I 06 will attract member I03 causing it to connect with terminal I05 and to move away from terminal I01, causing winding I06 to become deenergized. Upon the deenergization of winding I00, the resilience of member I03 will cause it to move away from terminal I05 and to connect with terminal I04 as well as with terminal I01. The circuit for winding I00 being then again completed through terminal I01, winding I00 will again attract member I03 causing the cycle of operation just described to be repeated. Winding I05 will then be repeatedly energized and deenergized as long as energy is supplied to its control circuit.

When member I03 connects with terminal I05, current is supplied to the right-hand portion of the primary winding I08 of a transformer F, and when member I03 connects with terminal I04, current is supplied in the opposite direction to the left-hand portion of primary winding I08 of transformer T. Alternating current, therefore, is induced in the secondary Winding I09 of transformer F.

The secondary winding I09 is connected to the line circuit for the section next in rear over front contacts of the relay PC, and winding I06 of alternator Q is controlled by the associated relays HR and DR in a manner similar to that described for the coding relay CT. That is, alternator Q operates to supply alternating current to the line circuit for the section next in rear whenever the associated relay DR is energized provided the associated relay HR. is decnergized or is energized by current of the proper polarity. In other words,

, the alternator Q functions to supply alternating current in a manner similar to that described for coding relay CT and, if desired, may be substituted for relay CT at any or all of the signals shown in Figs. 1A and 1B. For example, the alternator Q may be substituted for the relay IOCT at signal ms in Fig. 1A by connecting secondary I09 of transformer F to wires H0 and III and by connecting member I03 to wire H2 and winding I06 to terminal C.

From the foregoing description, it will be apparent that I have provided a simple and reliable system of three-block, four-indication, signaling utilizing asymmetric units for securing the different proceed indications over two line wires wherein the signals of the system are prevented from displaying a less restrictive indication, and in some cases are caused to display a more restrictive indication, in the event of a failure of the asymmetric units to function properly. Furthermore, in the event of failure of the alternating current source of energy in the modification utilizing a separate source of alternating current, my system continues to operate as a two-block, threeindication, system.

Although I have herein shown and described only a few forms 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, a pair of conductors for said section governed by trafiic conditions in said section, two signal control relays receiving energy from said conductors, means including asymmetric units for causing said two relays to assume one condition when said conductors are supplied with direct current and for causing said two relays to assume a different condition when said conductors are supplied with alternating current, a source of alternating cur rent and a source of direct current, and another relay controlled by said source of alternating current for connecting said conductors with said direct current source when said alternating current is absent.

2. In combination, a section of railway track, a pair of conductors for said section governed by traffic conditions in said section, two signal control relays receiving energy from said conductors, means including asymmetric units for causing said two relays to assume one condition when said conductors are supplied with direct current and for causing said two relays to assume a different condition when said conductors are supplied with alternating current, a source of alternating current and a source of direct current, and another relay controlled by said source of alternating current as Well as by traffic conditions in advance of said section for connecting said direct current source or said alternating current source with said conductors.

3. In combination, a section of railway track, a pair of conductors for said section governed by traiiic conditions in said section, two signal control relays receiving energy from said conductors, means including asymmetric units for causing said two relays to assume one condition when said conductors are supplied with direct current and for causing said two relays to assume a difierent condition when said conductors are supplied with alternating current, a source of alternating current and a source of direct current, and another relay controlled in accordance with traflic conditions in advance of said section for connecting said conductors either with said direct current source or said alternating current source but not both simultaneously.

4. In combination, a section of railway track, a pair of conductors for said section controlled by traiiic conditions in said section, means for reversibly supplying current to said conductors, two polarized relays connected to said conductors, asymmetric units associated with said relays for permitting current of one polarity but not of the other to pass through one relay and for permitting current of the second polarity but not of the first to pass through the other relay, a signal for said section capable of displaying a plurality of proceed aspects, circuit means including neutral and polar contacts of said relays for controlling the different aspects of said signal, and means including polar contacts of said relays for preventing the display of a less reaicasic strictive aspect by said signal in, the event said asymmetric units fail to function properly.

5. In combination, a section of railway track, a pair of conductors for said section controlled by traffic conditions in said section, means for reversibly supplying current to said conductors, two polarized relays connected to said conductors, asymmetric units associated with said relays for permitting current of one polarity but not of the other to pass through one relay and for permitting current of the second polarity but not of the first to pass through the other relay, a signal for said section capable of displaying a plurality of proceedaspects, circuit means including, neutral and polar contacts of said relays for controlling the different aspects of said signal, and means including polar contacts of said relays for causing the display of a more restrictive aspect by said signal in the event said asymmetric units fail to function properly.

6. In combination, a section of railway track, a pair of conductors for said section controlled by trafiic conditions in said section, means for reversibly supplying current to said conductors, two polarized relays connected to said conductors, asymmetric units associated with said relays for permitting current of one polarity but not of the other to passthrough one relay and for permitting current of the second polarity but not of the first to pass through the other relay, signal means for said section controlled by said relays, and means including neutral and polar contacts of said relays for controlling the supply I of current to the conductors for the section next in rear.

7. In combination, a section of railway track, a pair of conductors for said section controlled by trafiic conditions in said section, means for reversibly supplying current to said conductors, two polarized relays connected to said conductors, asymmetric units associated with said relays for permitting current of one polarity but not of the other to pass through one relay and for permitting current of the second polarity but not of the first to pass through the other relay, signal means for said section controlled by said relays, other signal means controlled by another pair of conductors, and means including polar contacts of said relays for controlling the supply of current to said other conductors whereby if said asymmetric units fail to function properly said other conductors are supplied with current of such character as to cause said other signal means to display a more restrictive indication.

8. A railway signal system comprising a stretch of railway track divided into blocks, a pair of conductors for each block controlled by trafiic conditions in that block, two relays for each block and each relay receiving energy from the associated conductors, asymmetric units associated with the relays for each block for permitting current of one polarity but not of the other to pass through one relay and for permittingcurrent of the second polarity but not of the first to pass through the other relay, means for supplying current of one polarity or current of the other polarity or alternating current to each pair, of conductors in accordance with traffic conditions in advance of the associated block; and a signal for each block controlled by the relays for that sectionand arranged to have a first aspect when both relays are deenergized, a second aspect when one relay is energized, a third aspect when the other relay is energized, and a fourth aspect when both relays are energized. V v

9. In combination, a section of railway track, a pair of conductors for said section governed by traffic conditions in said section, a si al controlled by said conductors and arranged to display its leastrestrictive aspect when said conductors are supplied with alternating current, a source of direct current, a device operative when energized toconvert direct current to alternating current, and means governed by traffic conditions in advance of said section for supplying current to energize said device and for connecting said device to said conductors thereby supplying the conductors with alternating current.

10. In combination, a section of railway track, a first relay and a second relay each having neutral and polar contacts, means effective to deenergize both relays when saidsection is occupied, means effective when said section is unoccupied for energizing only the first relay in the normal direction or only the second relay in the normal direction or both relays in the normal direction in accordance with trafiic conditions in advance of said section, a signal for said section including a first unit comprising a stop and a caution as well as a proceed lamp and a second unit comprising a stop and a proceed lamp, a circuit for the stop lamp of the first unit including a back contact of both relays, a circuit for the stop lamp of the second unit including a back contact of said second relay, a circuit for the caution lamp of the first unit including a front contact of said first relay and a back contact of said second relay, another circuit for said caution lamp including a back contact of said first relay as well as a front contact and a normal polar contact of said second relay, a circuit for the proceed lamp of said second unit including a back contact of said first relay as well as a front contact and a normal polar contact of said second relay, and a circuit for the proceed lamp of said first unit including a front contact and a normal polar contact of said first relay as well as a front contact and a normal polar contact of said second relay.

11. In combination, a section of railway track, a first relay and a second relay each having neutral and polar contacts, means effective to deenergize both relays when said section is occupied, means effective when said section is unoccupied for energizing only the first relay in the normal direction or only the second relay in the normal direction or both relays in the normal direction in accordance with traffic conditions in advance of said section, a signal for said section including a first unit comprising a stop and a caution as well as a proceed lamp and a second unit comprising a stop and a proceed lamp, circuits for said lamps controlled by said first and second relays whereby said signal iscaused to display a stop and three distinctive proceed indications respectively, an auxilary circuit for the caution lamp of the first unit including a reverse polar contact of said second relay, another auxiliary circuit for said caution lamp including a reverse polar contact of said first relay, and an auxiliary circuit for the stop lamp of said second unit including a reverse polar contact of said second relay, said auxiliary circuit being effective at times to provide a restrictive indication in the event said first and second relays become energized in the reverse direction.

12. In combination, a forward and a rear section of railway track, a first and a second relay each having neutral and polar contacts associated with said forward section, means for energizing only said first relay in the normal direction or only said second relay in the normal direction or both relays in the normal direction according to traflic conditions in advance of said forward section, a pair of conductors for the rear section, an auxiliary relay effective to connect said conductors with a source of alternating current or a source of reversible direct'current according as the auxiliary relay is energized or deenergized respectively, a circuit for said auxiliary relay including a back contact of said first relay as well as a front contact and a normal polar contact of said second relay, and another circuit for said auxiliary relay including a front contact and a normal polar contact of said first relay as well as a front contact and a normal polar contact of said second relay.

13. In combination, a forward and a rear section of railway track, a first and a second relay each having neutral and polar contacts associated with said forward section, means for energizing only said first relay in the normal direction or only said second relay in the normal direction or both relays in the normal direction according to traflic conditions in advance of said forward section, a pair of conductors for the rear section, a device for converting direct current to alternating current, a circuit for supplying said device with direct current including a front contact and a normal polar contact of said first relay as well as a front contact and a normal polar contact of said second relay, another circuit for supplying said device with direct current includ:

track, a control circuit, a source of direct cur.

rent, a device having contacts which are operative when the device is energized to convert direct current into alternating current, means governed by traffic conditions in advance of said,

section for at times connecting said control cir cuit to the contacts of said device and for at such times connecting said device to said source of direct current to thereby energize said device,

whereby said control circuit is supplied at such times with alternating current, and traific governing means for said section receiving energy from said control circuit and responsive uniquely to alternating current.

15. In combination with a section of railway track, a control circuit, a source -of direct current, a device having contacts which are operative when the device is energized to convert direct current into alternating current, means governed by trafiic conditions in advance of said section for at times connecting saidcontrol circuit to the contacts of said device and for at such times conmeeting said device to said source of direct current to thereby energize said device, whereby said control circuit is supplied at such times with alternating current, means also governed by, trafiic conditions in advance of said section for selectively supplying said control circuit with direct current from said source, and trafiic governing means for said section receiving energy from said control circuit and selectively responsive to direct current and alternating current.

16. In combination, a section of railway track, a pair of conductors for said section governed by trafiic conditions in said section, means for supplying said pair of conductors with current in one direction or the other in accordance with traffic conditions in advance of said section, two relays receiving energy from said pair of conductors, asymmetric units associated with said relays for permitting current of one polarity but not of 5 the other supplied from said conductors to pass through one relay and for permitting current of the second polarity but not of the first supplied from said conductors to pass through the other relay, a signal for said section governed by said 10 two relays, said signal being capable of displaying a clear indication and a plurality of different restrictive proceed indications, and means governed by said two relays for causing said signal to display a restrictive proceed indication in the event 15 said asymmetric units fail to function properly.

1'7. In combination, a section of railway track,

a pair of conductors for said section governed by trailic conditions in said section, means for supplying said pair of conductors with direct current 20 in one direction or the other or with alternating current in accordance with traffic conditions in advance of said section, two polarized relays receiving energy from said pair of conductors, asymmetric units associated with said relays for 2:; permitting current of one polarity but not of the other supplied from said conductors to pass through one relay and for permitting current of the second polarity but not of the first supplied from said conductors to pass through the other 30 relay, a signal for said section controlled by said two relays, said signal being capable of displaying a clear indication and a plurality of different restrictive proceed indications, and means governed by said two relays for causing said signal 35- to display a restrictive proceed indication in the event said asymmetric units fail to function properly,

18. In combination, a stretch of railway track divided into a plurality of successive block sec- 40 tions, a signal for each section capable of providing a stop indication and a plurality of different proceed indications, each section having a pair of conductors governed by traffic conditions: in said section and electroresponsive means ener-- 45 gized from said; conductors, said electroresponsive means assuming one condition when not energized, a second condition when: supplied only with unidirectional current of one relative polar-- ity, a third condition when supplied only'with 5Q: unidirectional, current of theother relative polarity, and a fourth condition when supplied with alternating current, each section also having? associated therewith a supply device operativei on the supply of j direct current thereto to con- 55'- vert said direct current into alternating current and to supply such alternating current to a" cir-- cuit through which current may-be supplied to the conductors of the adjacent block'section in' the rear, the electroresponsive means for'each 00' section being selectively-operative inaccordance with its condition to control the signalfor' such section, the supply of direct current to the supply device for such section, and the polarityof 'the" unidirectional current supplied to the conductors 65'. of the adjacent block section in the rear.

19. In combination with a section of railway track, a control circuit, a source of direct current,

a supply device having contacts, said supply 'device being operative when and only when said'ml contacts are operated to convert direct current into alternating current which may be supplied to said control circuit, the contacts of said supply device being operated when and only when direct current is supplied to said device,.means con'- 75;.

trolled by traffic conditions in advance of said section for at times supplying direct current to said supply device to thereby effect the supply of alternating current to said control circuit, and trafiic governing means for said section receiving energy from said control circuit and responsive uniquely to alternating current.

20. In combination, a stretch of railway track divided into a plurality of successive block sections, a signal for each section capable of providing a stop indication and a plurality of different proceed indications, each section having a pair of conductors governed by traific conditions in said section, each section also having electroresponsive control means energized from the conductors for such section and controlling the signal for such section, each section having a supply device having contacts, said device being operative only when said contacts are operated to convert direct current into alternating current which may be supplied to the conductors of the adjacent section in the rear, the contacts of said device being operated only when direct current is supplied to said device, the control means for each section assuming one condition when deenergized, a different condition when supplied with direct current and a still dilTerent condition when supplied with alternating current, the control means for each section being selectively operative in accordance with its condition to control the signal for the section with which said control means is associated, to at times effect the supply of direct current to the supply device for such section, and to also control the supply of direct current to the conductors of the adjacent block section in the rear.

21. In combination, a stretch of railway track divided into a plurality of successive block sections, a signal for each section capable of providing a stop indication and a plurality of different proceed indications, each signal having associated therewith electroresponsive control means and controlling the signal, each signal having associated therewith a supply device having contacts, said supply device being operative only when said contacts are operated to convert direct current into alternating current which may be supplied to the electroresponsive means associated with the adjacent signal in the rear, the contacts of said supply device being operated only when direct current is supplied to said device, the control means associated with each signal assuming one condition when deenergized, a different condition when supplied with unidirectional current and a still difierent condition when supplied with alternating current, the control means associated with each signal being selectively operative in accordance with its condition to control the signal with which it is associated, to at times effect the supply of direct current to the supply device associated thereWith and to also control means for supplying unidirectional current to the control means associated with the adjacent signal in the rear.

22. In combination, a section of railway track, a pair of conductors for said section governed by trafiic conditions in said section, means for supplying said pair of conductors with current of one polarity or the other in accordance with traffic conditions in advance of said section, two relays receiving energy from said pair of conductors, asymmetric units associated with said relays for permitting current of one polarity but not of the other supplied from said conductors to pass through the winding of one relay and for permitting current of the other polarity but not of the first supplied from said conductors to flow through the winding of the other relay, a signal for said section governed by said two relays, said signal being capable of displaying a clear indication and a plurality of difierent restrictive proceed indications, and means governed by said two relays and operative in the event said asymmetric units fail to function properly to condition the signal to display a proceed indication at least as restrictive as that which would be displayed if the asymmetric units were functioning properly.

HENRY S YOUNG.

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