US2287144A - Railway signaling system - Google Patents

Description

June 23, 1942. c. E. STAPLES RAILWAY SIGNALING SYSTEM Filed Feb. 3, 1940 ea or Steady Aneryy.

BY 4 h'" 62 baudmwa ms ATTORNEY Patented June 23, 1942 @FKQE RAILWAY SIGNALING SYSTEM Crawford E. Staples, Wilkinsburg, Pa, assignor to The Union Switch & Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application February 3, 1940, Serial No. 317,161

2 Glaims.

It has heretofore been proposed to provide means operable in the event an insulated joint separating two track sections is defective to establish a lockout circuit to supply steady uncoded energy to the section inthe rear of the defective joint 50 that this energy will feed over the defective joint and maintain the track relay of the section in advance of the defective joint constantly energized to thereby cause the signal controlled by that track relay to display its most restrictive indication.

One means for accomplishing this result is shown in an application of Howard A. Thompson, filed May 28, 1938, Serial No. 210,743, for Railway trafiic controlling apparatus, now U. S. Patent 2,213,420, granted Sept. 3, 1940. Another means for accomplishing this result is shown in an application of Ralph R. Kemmerer, filed June 30, 1939, Serial No. 282,185, for Railway.

signaling system, now U. S. Letters Patent 2,215,- 904, granted Sept. 24, 1940, while still another means for accomplishing this result is shown in an application of Leslie R. Allison and Frank H. Nicholson, filed February 24, 1940, Serial No. 320,654, for Railway signaling system, now U. S. Patent 2,235,134, granted Mar. 18, 1941.

It is an object of my invention to provide an improved railway signaling system incorporating a lockout circuit, the system being arranged so that it is non-cascading in operation, and being also arranged so that less equipment is required than is necessary in the systems heretofore known.

A further object of the invention is to provide a railway signaling system incorporating an improved non-cascading lockout circuit.

Other objects of my invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawing.

I shall describe one form of railway signaling system embodying my invention and shall then point out the novel features thereof in claims.

In the drawing, the single figure is a diagram showing a railway signaling system embodying my invention.

Referring to the drawing, there is shown therein a stretch of railway track having track rails I and 2 over which trafiic normally moves in the direction indicated by the arrow, that is, from left to right. The rails of the track stretch are separated by insulated joints 3 into the customary successive track sections, and the rails of each of these sections form a part of a track circuit of the usual character.

The particular track stretch which is represented in the drawing is intended for use in a railway system employing electric current for propulsion purposes, and for this reason alternating current track circuit energy is used together with impedance bonds 4 of the customary form which conduct the propulsion current around each pair of insulated rail joints. As the description proceeds, however, it will be apparent that the apparatus of this invention is equally well suited for use on a steam road in which the application of either direct or alternating current track circuit energy for control of the signals may be employed. In such an application the impedance bonds 1 would, of course, be omitted.

In the diagram comprising the drawing, one complete track section, which is identified as section I2T, and parts of two other sections identified as sections HT and IET, are shown. Each of these track sections has located at the entrance end thereof a signal for governing movement of trains in the track stretch, the

signal for section l2'I being identified as 28.

The signal illustrated is of the familiar color light type having a green or proceed lamp G, a yellow or causticn lamp Y, and a red or stop lamp R. It should be understood, however, that the invention is not restricted to the use of a signal of this type and that any appropriate kind of signal may be employed.

The rails of each track section form a part of a track circuit to which coded alternating current signal control energy is supplied at the exit or leaving end from the secondary of a track transformer designated TT with a prefix corresponding to that of the associated track section. The circuits for supplying current from the secondary windings of the track transformers include the usual current limiting reactors 6. The energy supplied to the track circuits is supplied from any suitable source, and may be distributed throughout the track stretch by a transmission line, not shown. In the drawing, the terminals BX and CX designate the terminals of such power supply source, and it will be assumed that the energy supplied from the source is alternating current with a frequency of 100 cycles per second.

Each of the signal locations has associated therewith a suitable source of direct current, such as a primary or storage battery, not shown, the terminals of which are designated in the drawing by the reference characters B and C.

The particular signaling system shown in the drawing is of the three indication variety, and it makes use of track circuit energy coded at two different frequencies. This coded energy is provided by code transmitters CT which interrupt the supply circuits of the associated track transformers a definite number of times a minute according to tramc or other conditions ahead. In the form shown, each code transmitter CT is provided with two circuit making and breaking contacts 15 and 180 which are continuously-actuated by a motor or other suitable mechanism at two different speeds. For purposes of illustration it will be assumed that these speeds are such as to respectively provide 15 and I80 energy impulses per minute which are separated by periods of equal duration in which no energy is supplied.

Each of the track circuits includes a code following track relay designated TR. together with an appropriate prefix. The track relay is located at the entrance end of the track section and may be of any suitable type. As shown, the relay is of the direct current type having its winding connected to the track rails of the associated track section through a suitable resonant unit RU shown diagrammatically in the drawing.

The resonant units RU each comprise a transformer, a capacitor and a reactor so arranged and proportioned as to freely pass the lflil cycle coded signal control energy, but so as not to pass propulsion current of a different frequency. Each resonant unit includes, in addition, a rectifier which converts into direct current the alternating current which is supplied through the unit.

The track relay I2TR. has associated therewith auxiliary relays i2FSA, [2H and I2J, while each of the other signals in the track stretch has associated therewith equipment corresponding to that associated with signal I2S.

Referring to the drawing, contact 15 of the track relay I2TR controls the supply of current to the primary winding 20 of the decoding transformer I2DT, while contacts I6 and I! control the supply of current to windings of relays IZFSA and HE.

As shown in the drawing, contact l when released engages a contact which is connected to one end terminal of the transformer primary winding 20, while contact l5 when picked up engages a contact which is connected to the other end terminal of the winding 26. The center terminal of the winding 20 is connected to terminal C of the source of direct current, and, accordingly, when contact l5 of relay I2TR is picked up and released, the two end portions of the transformer primary winding 20 are alternately energized with the result that current is induced in the transformer secondary windings 2| and 22.

The contact iii of track relay IZTR. is connected to the center terminal of the transformer secondary winding 2|, while one end terminal of the winding 21 is connected to one terminal of the pick-up winding 24 of relay IZFSA. The other terminal of the winding 24 is connected to a contact which is engaged by track relay contact l6 when contact It is in its released position.

Contact I6 when picked up engages a contact which is connected to contact 25 of relay IZFSA, while contact 25 when pickde up engages a contact which is connected to one terminal of the winding of relay IZH, the other terminal of which is connected to an end terminal of the transformer secondary winding 2|.

The relay IZFSA has a holding winding 21 one terminal of which is constantly connected to terminal C of the source of current, while the other terminal of the winding 21 is connected to contact 23 of relay IZFSA. Contact 28 when picked up engages a contact which is connected to contact 29 of relay [2H, while contact 29 when released engages a contact which is connected to a contact which is engaged by track relay contact H when contact I? is picked up.

The secondary winding 22 of decoding transformer IZDT is connected to the resonant unit I2RUA from which current is supplied to the winding of the relay l2J. The resonant unit IZRUA is similar in construction to the unit i2RU, and the elements of the unit are arranged and proportioned so that the unit will transmit sufficient current to the winding of relay IN to maintain the contact of relay I2J picked up when the frequency of the current induced in the transformer secondary winding 22 is that which is present when the track relay I2TR is responding to energy of the I code frequency. The unit I'ZRUA is also arranged and proportioned so that when the track relay IZTR is responding to energy of any other code frequency, such as 75 code frequency, insufficient energy is supplied to the winding of relay l2J to maintain the contact of that relay picked up.

The relay iZI-I is of a type the contacts of which are slow in releasing with the result that the relay contacts when picked up remain picked up during the intervals between the supply of impulses of energy to the relay winding, while the contacts also remain picked up during momentary interruptions in the supply of impulses of energy to the relay winding, such as occur when the code supplied to the track relay is changed from one frequency to another. In addition, the contacts of relay I2H when picked up remain picked up until after the contacts of relay IZFSA become released when the supply of energy to the windings of these relays is discontinued as a result of cessation of code following operation of the track relay.

The relay I2I-I and the transformer l2DT are selected and proportioned so that the contacts of the relay, when released, will not become picked up on the supply of one impulse of energy from the transformer secondary winding 2| to the relay winding, but will become picked up on the supply of two or more of these impulses in rapid succession, such as occur when code following operation of the track relay is initiated.

The auxiliary relays IZFSA and IZH cooperate to control the supply of energy to the primary winding 32 of track transformer H'IT, and to also control the circuits of the lamps of signal I2S in the manner hereinbefore explained in detail.

The equipment is shown in the drawing in the condition which it assumes when the track sections |2T and I3T are vacant, at which time the equipment associated with section |3T operates in the manner hereinafter described in detail in connection with section I2T to supply en ergy of the 180 code frequency to the track transformer I2TT, while this energy feeds to the track relay IZTR to produce code following operation of the contacts thereof.

As a result of movement of the track relay contact l5 between its released and picked-up positions, the end portions of the transformer primary winding 28 are alternately energized and current is induced in the secondary windings 2| and 22 of the transformer IZDT.

On each movement of the track relay contact I6 to its released position, the circuit is established to supply an impulse of energy from the left-hand end portion of the transformer secondary Winding 2| to the winding 24 of relay IEFSA. This circuit is traced from the center terminal of the transformer secondary winding 2! through back contact [6 of track relay IZTR, and winding 24 of relay IZFSA to the left-hand end ter1ninal of the secondary winding 2 I.

As a result of the supply of impulses of energy to the winding 24 of relay IZFSA, the contacts of this relay are maintained picked up and contact 25 establishes the circuit for supplying energy to the winding of relay EEH when the track relay contacts are in their picked-up position. Accordingly, when contact it engages its front contact energy is supplied to the winding of re lay 12H from the right-hand end portion of the transformer secondary winding 2i over the circuit which is traced from the center terminal of the transformer winding 2i through front contact 13 of track relay lZTR, front contact 25 of relay I'ZFSA, and winding of relay l'ZH to an end terminal of the winding 2 i.

As a result of the supply of impulses of energy to the winding of relay i2H, the contacts of this relay are maintained picked up and contact 29 interrupts the circuit of the holding Winding 2! of relay IZFEJA with the result that engagement of contact ll of the track relay HZTR. with its front contact does not afiect the supply of energy to the winding 27 of relay IEFSA.

Since the contacts of the track relay lETR are responding to energy of the 18!) code frequency, "the frequency of the current induced in secondary winding 22 of transformer IEDT is such that it is freely passed by the resonant unit IZRUA, and this unit supplies sufiicient current to the winding of relay IZiJ to maintain the contact of that relay picked up.

As contact 35 of relay lZH is picked up and as contact 35 of relay HZJ is also picked up, the circuit for supplying energy to the green or procceed lamp G of signal I28 is complete, and is traced from terminal B of the source of current through front contact 34 of relay 021-1, and front contact 35 of relay I2Ji to one terminal of the lamp G, the other terminal of which is connected to terminal C of the source of current.

At this time, as the contacts of relays IZFSA and IZI-I are picked up, the circuit for supplying energy of the 180 code frequency to the track transformer l I'I'T is complete, and is traced from terminal BX of the source of signal current through front contact 36 of relay IZH, contact EBB of code transmitter I2CT, and front contact 33 of relay IEFSA to one terminal of the transformer primary winding 39, the other terminal of which is connected to terminal CX of the source of signal control energy.

Operation of the equipment on movement of a train in the normal direction of traffic When a train moving in the normal direction of traffic enters section I2T it shunts the track relay 12TH, with the result that the contacts of this relay thereafter remain in their released position, and energy is not induced in the secondary windings 2| and 22 of transformer 'IEDT, while contact "of the track relay interrupts the circuit through which energy is at times supplied to the holding winding 27 of relay IZFSA.

As energy is no longer induced in secondary winding 2 I, impulses of energy are no longer supplied to the winding 24 of relay IZFSA, and as contact I6 of track relay |2TR is in its released position thecircuit of the Winding of relay I2H is interrupted. As a result the contacts of the relay IZFSA and l2I-I become released. At this time as contact ll of the track relay IZTR is released, the circuit of the holding winding 2? of relay I'ZFSA interrupted and cannot be established during release ofthecontacts of relays tQFSA and IZH.

In addition, as current is not induced in secondar winding 22 of transformer liiDT, energy is no longer supplied to the winding of relay iZJ, and the contact-oi that relay becomes released.

On release of contact 38 of relay iiZ'FSA, the circuit for supplying energy of the Hill code frequency to the track transformer HTI is interrupted, while on release of contact .35 of relay IZH the circuit for supplying energy of the 15 code frequency to the track transformer HTT is established. This circuit is traced from terminal BX of the source of signal control current through back contact 36 of relay I'ZH, contact ll) of code transmitter l2CT, and back contact d8 of relay IZFSA to one terminal of the winding 39 of transformer H'IT, the other terminal of which is connected 'toterminal OX of the source of signal control current.

In addition, on release of the contacts of relay IZH, contact 35 interrupts the previously traced circuit for illuminating the green lamp G, and establishes the circuit to illuminate the red or stop lamp R of signal I28. This circuit is traced from terminal B of the source of current through back contact 34 of relay I2H to one terminal of the red lamp R, the other terminal of which is connected to terminal C of the source of current.

As the train proceeds through the track stretch and enters section I3'I, the track relay for that section is shunted and the equipment associated therewith operates in the manner described in detail in connection with section IZT to condition the signal for section lST to display its red or stop indication, while the energy supplied to the rails of section I2T is changed from Hill code frequency to 15 code frequency,

As long as any portion of the train remains in section lZT, the track relay [2TB continues to be shunted, but when the rear of the train vacates section I2T, the impulses of energy supplied by track transformer I-Z'IT to the track rails of section IZT feed to the track relay 12TH and produce code following operation of the contacts thereof.

On initial movement of the track relay contact I5 from the released to the picked-up position there is a change in energization of the primary winding 28 of transformer IZDT, and an impulse of energy is induced in secondary winding 2!. At this time, however, since contact 16 of the track relay is in its picked-up position, the circuit of the winding 24 of relay IZFSA is interrupted, while as contact 25 of relay l2FSA is released the circuit of the winding of relay [21-1 is interrupted. Accordingly, energy is not supplied from secondary winding 2| of transformer I2DT to the winding of either of the relays IEFSA and 12H on the first picked-up period of the track relay contacts.

In addition, at this time, as contact 28 of relay I2FSA is released the circuit of the holding winding 21 of the relay is interrupted, and energ is not supplied to this winding at this time.

On movement of the track relay contacts to their released position following their initial movement to the picked-up position, there is another change in energization of the primary winding 28 of transformer IZDT, and another impulse of energy is induced in secondary winding 2|. At this time, as contact IE of the track relay is in its released position, the circuit for supplying energy from the transformer secondary Winding 21 to the winding 24 of relay IZFSA is complete, and hence an impulse of energy is supplied to the winding 24 of relay IZFSA and the relay contacts become picked up.

On picking up of the contacts of relay I2FSA contact 43 interrupts the circuit for supplying energy of the 75 code frequency to the track transformer TI, and establishes the lookout circuit for supplying steady uncoded energy to the transformer ET. This circuit is traced from terminal BX of the source of signal control current through back contact 36 of relay I2H, and front contact (ill of relay HFSA to primary winding 39 of transformer HT'I'.

As a result of picking up of the contacts of relay IQFSA contact 25 establishes the circuit of the winding of relay IZH so that on the next or second picked-up period of the track relay contacts an impulse of energy is supplied'from the transformer secondary winding 2i to the winding of rela liiH. However, as explained above, the contacts of the relay IZI-I do not become picked up on the supply of the first impulse of energy to the relay winding, and the contacts of relay IZI-I remain released at this time.

At this time as the contacts of relay IZFSA are picked up and the contacts of relay 12H are released, an impulse of energy is supplied to the holding winding 21 of relay IZFSA over the circuit which is traced from terminal B of the source of direct current through front contact i? of track relay IETR, back contact 29 of relay i2H, front contact 28 of relay IZFSA, and winding 2? to terminal C of the source of current. Energization of the holding winding 2? at this time aids in maintaining the contacts of the relay lQFSA picked up and assures that the lockout circuit will be maintained until it is interrupted b picking up of the contacts of relay I2H.

On thenext or second released period of the track relay contacts another impulse of energy is supplied to the winding 24 of relay I2FSA, and the contacts of this relay are maintained picked up so that on the next or third picked-up period of the track relay contacts another impulse of energy is supplied to the winding of relay 12H.

At the time the second impulse of energy is supplied to the winding of relay IZH, the flux developed in the relay core as a result of the supply of the first impulse of energy to the relay winding will not have completely died out, and the second impulse of energy supplied to the relay winding will cause the flux in the relay core to build up to a value high enough to cause the relay contacts to become picked up.

On picking up of the contacts of relay [2H, contact 29 interrupts the previously traced circuit for supplying energy to the holding winding 21 of relay IZFSA, while contact 36 of relay 12H interrupts the previously traced lockout or steady energy supply circuit for supplying steady energy to the track transformer H'IT.

On picking up of contact 36 of relay [2H, the circuit for supplying energy of the I code frequency to the track transformer l ITT is complete, and is traced from terminal BX of the source of signal control cur-rent through front contact 36 of relay l2I-I, contact I80 of code transmitter IZCT, and front contact 38 of relay EZFSA to one terminal of the primary winding 39, the other terminal of which is connected to terminal CX of the source of signal control current.

At this time as the track relay IZTR is responding to energy of the 15 code frequency, the frequency of the current induced in the secondary winding 22 of transformer I'ZDT is such that it is not freely passed by the resonant unit IZRUA, and too little current is supplied to the winding of relay |2J to pick up the contact of this relay. Accordingly, on picking up of the contact 34 of relay [2H the circuit of the red lamp R is interrupted, and the circuit for lighting the yellow lamp Y is established, and is traced from terminal B of the source of current through front contact 34 of relay 12H, back contact 35 of relay I2J, and lamp Y to terminal C of the source of current.

When the train has advanced far enough in the track stretch to vacate section I3T, the equipment associated therewith operates in the manner described in detail in connection with the equipment associated with section I2T to supply energy of the l8il code frequency to the transformer IETT. On this change in the frequency of the energy supplied to the rails of section 121, and thus to the track relay IZTR, the track relay contacts operate at a higher speed, and the windings of the relays IZFSA and WE are maintained energized, while the resonant unit IZRUA supplies sufiicient energy to the winding of relay IZJ to pick up the contact of this relay.

On picking up of contact 35 of relay I 2J the circuit of the yellow lam Y is interrupted, while the circuit of the green lamp G is established, and is traced from terminal B of the source of current through front contact 34 of relay I2H, front contact 35 of relay I2J, and lamp G to terminal C of the source of current.

On this change in the rate of operation of the track relay contacts, the windings of relays EEFSA and lZI-l are maintained energized, and the contacts of these relays are maintained picked up, and maintain the circuit for supplying energy of the I80 code frequency to the track transformer HTT.

Operation of equipment in the event an insulated joint breaks down as a Tesuit of passage of a train For purposes of illustration it will be assumed that the track stretch is vacant so that energy of the I80 code frequency is supplied to the rails of section I2T, that a train moving in the normal direction of traffic passes through the track stretch, and that an insulated joint 3 separating sections HT and I2T breaks down as a result of passage of a train.

In electrified territory because of the wellknown operation of the impedance bonds 4, breaking down of one insulated joint has the same effect as breaking down of both insulated joints in steam propulsion territory, and permits the impulses of current supplied to the section in the rear of the defective joint to feed to the track relay of the section in advance of the defective joint.

When the train under consideration enters the section I2T it shunts the track relay IZTR and the equipment associated therewith operates in the manner heretofore explained in detail to condition the signal |2S to display its red or stop indication, while energy of the i5 code frequency is supplied to the track transformer l ITT.

When the train advances in the track stretch far enough for the rear end thereof to be located in advance of the track relay IZTR, the impulses of energy supllied to the rails of section HT feed over the defective insulated joint 3 to the winding of relay IZTR, but because of the shuntin action of the wheels and axles of vehicles forming the train too little current is supplied to the winding of the track relay IZTR, to pick up the contacts thereof until the train has advanced some distance beyond the point of connection of the winding of relay I'Z'IR with the track rails of the section I2T. When the train has advanced this far sufficient energy will be supplied to the winding of relay IZTR, as a result of the impulses of energy feeding over the defective joint 3 to pick up the contacts of relay IZTR and code following opera tion of the relay contacts will result.

On the first movement of the track relay contacts to their pickedu o position, there is a change in the energization of primary winding 2!) of transformer I2DT, as explained above, so

that impulses of energy are induced in the secondary windings 2| and 22. At this time, however, energy is not supplied to the Winding of relay 12H since contact 25 of relay IZFSA is released, while the circuit of the winding 24 of relay IEFSA is not complete since contact l6 of track relay I Z'IR is picked up.

Accordingly, on this first movement of the track relay contacts to their picked-up position, the contacts of the relays IZFSA and ME remain released.

On the first off period following the first on period in the code feeding over the defective joint, the contacts of the track relay IZTR become released and there is another change in the energization of transformer primary winding 25 so that another impulse of energy is induced in the secondary win-dings 2i and 22. On release of the track relay contacts, contact I E completes the previously traced circuit for supplying an impulse of energy from the secondary winding 2| to the winding 24 of relay IZFSA and the contacts of relay iEFSA become picked up.

As a result of picking up of the contacts of relay IZFSA, contact 45 interrupts the circuit for supplying energy of the '55 code frequency to the track transformer HTT, and establishes the steady energy or lockout circuit for supplying steady uncodecl energy to the transformer l ITT.

In addition, as a result of the picking up of the contacts of relay iBFSA, contact 28 partially establishes the circuit for supplying energy to the holding winding 2? of relay IZFSA, this circuit being completed on subsequent picking up of the track relay contact it, while contact as of relay IZFSA establishes the circuit for supplying energy to the winding of relay l2I-I.

As the result of the supply of steady energy to the transformer l ITT through the steady energy or lockout circuit, energy feeding over the defective joint picks up the contacts of track relay IZTR, and another impulse of energy is induced in secondary windings 2i and 22 of transformer lZDT. In addition, as a result of the picking up of the track relay contacts, contact I! completes the circuit for supplying energy to the holding winding 2? of relay I2FSA, this circuit being complete at this time since contact 29 of relay lZH is released-and contact 28 of relay IZFSA is picked up.

On picking up of the track relay contacts, contact i5 establishes the circuit for supplying energy from the transformer secondary winding 2| to the winding of relay 12H and an impulse of energy is supplied to the winding of relay IZH. However, as pointed out above, the relay IZH and the transformer IZDT are selected and proportioned so that the contacts of this relay do not become picked up on the supply of one impulse of energy to the relay winding, and hence the contacts of this relay remain released, and contact 29 maintains the circuit for supplying energy to the holding winding 2'! of relay HEFSA, while contact 38 of relay iZH maintains the steady energy or lockout circuit for supplying steady uncoded energy to the track transformer HTT.

As the lockout circuit for supplying steady energy to the track transformer HTT is maintained, steady energy feeds over the defective joint and holds the contacts of the track relay lZTR constantly picked up with the result that there are no further changes in energization of the primary winding 28 of transformer IZDT. Accordingly, no further impulses of energy are induced in secondary windings 2i and 22, and energy is not supplied to the Winding of relay 12H even though contact 25 of relay |2FSA and contact E6 of track relay i2TR are both picked up. The contacts of relay IEH therefore remain released and contact 36 maintains the lookout circuit, While contact 29 maintains the circuit of the holding winding 2'! of relay IZFSA, and contact 34 maintains the circuit of the red or stop lamp R of signal 128.

As a result of the supply of steady energy to the transformer IITT, the contacts of the track relay for section HT are maintained constantly picked up, and the signal for that section is conditioned to display its red or stop indication, but as hereinafter explained in detail, the equipment associated with the track relay for section T will operate to supply energy of the 15 code frequency to the adjacent section in the rear.

Operation of the equipment if an insulated joint breaks down when the strewn is vacant For purposes of illustration it will be assumed that an insulated joint 3 separating sections HT and lZ'I' breaks down at a time when the track stretch is vacant, at which time energy of the iSi! code frequency is supplied to the rails of section IZT.

As the relay QETR is assumed to be responding to energy of the Mid code frequency, the contacts of all of the auxiliary relays associated with relay EZ'IR are picked up, and energy of the ISO code frequency is supplied to the rails of section HT, while the signal l2S is conditioned to display its green or proceed indication.

If at the time the insulated joint separating sections HT and IZT breaks down the impulses of energy supplied to section T are out of step with those supplied to the rails of section IZT, the impulses of energy supplied to the rails of section I IT, and feeding over the defective insulated joint to the relay IZTR, will fill in the off periods in the code supplied to the section IZ'I', with the result that the contacts of the relay IZTR will be maintained picked up all or substantially all of the time.

If at the time the insulated joint separating sections HT and |2T breaks down the impulses of coded energy supplied to the rails of section I IT are substantially in step with those supplied to the rails of section IZT, they will soon become out of step. This will be true because the codes for the two sections are generated by different code transmitters and these code transmitters are operated by separate motors. These motors will not operate at exactly the same speed, and if at the time the joint breaks down the impulses of code are in step, they will soon become out of step because of the difference in the speed of the motors driving the code transmitters. When the impulses of code become out of step, there will be an increase in the duration of the picked-up periods of the track relay contacts due to the increase in the portion of the total time during which energy is supplied to the relay winding.

In consequence of the lengthened picked-up periods of the contacts of the track relay IZ'I'R, the contact 16 of track relay IZTR. will not engage its back contact, or will engage it for such short time intervals, that energization of the winding 24 of relay IZFSA is reduced below the value effective to maintain the relay contacts picked up.

On release of the contacts of relay IZFSA, contact 38 interrupts the circuit for supplying energy of the I80 code frequency to the track transformer HTT, and establishes a circuit to supply steady energy to the transformer H'I'I. This circuit is traced from terminal BX of the source of signal control current through front contact 36 of relay IZH, and back contact 38 of relay IZFSA to one terminal of the primary winding 39 of transformer HTT.

On the supply of steady energy to the transformer HT'I, steady energy is supplied to the rails of section HT and feeds over the defective joint to the track relay I2TR and maintains the track relay contacts constantly picked up.

As the contacts of track relay IZTR are picked up all or subbstantially all of the time by the scrambled code supplied thereto prior to the release of the contacts of relay IZFSA, and are constantly picked up by the steady energy supplied to the relay winding after the release of the contacts of relay IZFSA, little or no change occurs in the energization of the primary winding 2 9 of transformer IZDT, and hence very weak impulses of energy or none at all are induced in secondary winding 25. Accordingly, even though contact I6 of the track relay IZTR is picked up to establish the circuit for supplying energy from the winding 2! to the winding of relay IZI-I, no current or very weak impulses of current are supplied to the winding of relay iZH, and after a time interval the contacts of the relay l2I-I become released.

It is to be observed that the contacts of the relay IZH remain picked up until after the contacts of the relay IZFSA become released because of the slow release characteristic of the relay IZI-I.

On the release of the contacts of relay IZI-I, contact 34 interrupts the circuit of the green lamp G, and establishes a circuit for illuminating the red or stop lamp R.

In addition, on release of the contacts of relay 52H, contact 36 interrupts the previously traced circuit for supplying steady energy to the track transformer HTT, and engages its back contact to complete the circuit for supplying energy of the code frequency to the transformer IITT.

On the supply of energy of the 15 code frequency to the transformer HTT, energy of this frequency is supplied to the track rails of section II T, and feeds over the defective joint where it combines with the energy of I code frequency supplied by track transformer I2TT.

As a result of the supply of energy of the two code frequencies to the track relay IZTR, the relay contacts are picked up most of the time, but a time will quickly be reached when the relationship of the two codes is such that the contacts of the track relay will become released, thereby producing a change in the energization of primary winding 20 of transformer IZDT with the result that an impulse of energy is induced in secondary windingg 2|. In addition, on release of the track relay contacts, contact l6 establishes the circuit for supplying energy from the secondary winding 2| to the winding 24 of relay IZFSA, and the contacts of relay IZFSA become picked up.

As a result of picking up of the contacts of track relay IZFSA, contact 40 interrupts the circuit for supplying energy of the 15 code fre-' quency to the track transformer HTT, and. establishes the lockout or steady energy supply circuit for supplying steady uncoded energy to the transformer HTT. This steady energy will feed over the defective joint to the track relay IZTR and cause the track relay contacts to again become picked up, while on picking up of the contacts of the track relay IZTR, contact I! completes the circuit for supplying energy to the holding winding 2'! of relay IZFSA. This circuit is complete at this time since the contacts of relay IZH are released and the contacts of relay IZFSA are picked up, while on the supply of energy to the holding winding 21, the contacts of relay IZFSA are thereafter constantly picked up to maintain the steady energy or lookout circuit.

In addition, on the supply of steady energy to the track relay IZTR, the relay contacts are constantly picked up so that there is thereafter no further change in the energization of primary winding 29 of relay lZDT.

On the movement of the track relay contacts to their picked-up position as the result of the supply of steady energy over the lookout circuit, there is a change in the energization of primary winding 20 and energy is induced in the secondary winding, while contact l6 of the track relay establishes the circuit for supplying an impulse of energy to the winding of relay IZH. However, as previously pointed out, the characteristics of the relay IZI-I are such that the relay contacts when released will not become picked up on the supply of a single impulse of energy to the relay winding, and hence the relay contacts remain released at this time and maintain the lookout or steady energy circuit, and also maintain the circuit for supplying energy to the holding winding 21 of relay IZFSA.

Operation of the equipment when steady energy is supplied to a track: relay by means other than the lockout ,circuit controlied by that relay also makes it possible to employ steady energy to discontinue operation of highway traffic signals or for other purposes.

For purposes of illustration it will be assumed that an insulated joint 3 separating sections IZT and I3T breaks down as a result of passage of a train, and that the equipment associated with section IST operates in the manner described in detail in connection with section IZT to first supply energy of code frequency to the rails of section I2T, and to thereafter establish the lockout circuit controlled thereby to supply steady energy to the rails of section IZT.

As explained above, when any part of the train is present in section IZT, the track relay IZTR. is shunted, while when the train enters section IST the track relay for that section is shunted and the equipment controlled thereby operates to supply energy of the 15 code frequency to the track transformer IZTT.

As soon as the train vacates section IZT, the energy of 75 code frequency supplied to the transformer lZT-T, and by it to the rails of section IZT, will feed to the track relay IZTR and effect code following operation of the contacts thereof.

At this time impulses of energy of the 15 code requency supplied to the rails of section I2T will also feed over the defective joint to the rails of section l3T, but a short time interval will elapse before the train will have advanced far enough in the track stretch for the energy feeding over the defective insulated joint to effect operation of the track relay for section IST to establish the lookout circuit to supply steady uncoded energy to the rails of section IZT, and, accordingly, the track relay IZTR, will respond to energy of the 15 pulse frequency during this time interval.

On the supply of coded energy to the track relay IZTR, the contacts of the relay IZFSA become picked up on the first released period of the track relay contacts, as explained above, while the contacts of the relay 12H become picked up on the third picked-up period of the track relay contacts. When the contacts of the relays IZFSA and 125 are picked up, the circuit for supplying the energy of I80 code frequency to the track transformer HTT is complete, while the circuit for illuminating the yellow or caution lamp Y of signal IZS is established.

When the train has advanced some distance in section EST the impulses of energy feeding over the defective icint from section EIZT cause o;oeration of ti U aok relay for section i3T to establish the lockout circuit so that steady uncoded energy is supplied to the rails of section lZT. This energy feeds to the track relay IQTR and maintains the relay contacts constantly picked up.

When the contacts of track relay IETR are constantly picked up, the circuit of the winding 24 of relay I2FSA is interrupted, while thereafter no changes occur in energization of the transformer primary winding 2%), so that energy is not supplied from the transformer secondary winding 2! to the winding of relay lEH. Accordingly, the contacts of the relays E2FSA and 62H become released.

However, because of the slow release characteristic of the relay [2H, the contacts of this relay remain picked up until after the contacts of the relay SZFSA become released. This eliminates all possibility that energy will be supplied to the holding winding 2? of relay EZFSA at this time, since contact 23 of relay IZFSA interrupts the circuit of the holding winding before contact 29 of relay lZH becomes released to establish the circuit.

As the holding Winding 2? of relay lEFSA is not energized, the contacts of relay 1 EFSA become released and remain released, and as the contacts of relay EZl-I are also released, the circuit for supplying energy of the code frequency to the track transformer l iTT is established, while contact 3d of relay EZH establishes the circuit for illuminating the red or stop lamp R of signal we.

From the foregoing it will be seen that when an insulated joint separating two track sections breaks down. as a result of passage of a train, and the equipment associated with the section in advance of the joint operates to establish the lookout circuit to supply energy to the section i the rear of the defective joint, that the ecu nent associated with the track relay of the secti I in the rear of the defective joint will be condition d to cause the for that section to display its stop indication, and that the supply of steady energy to the section further in the rear will not be repeated, but on the contrary, coded energy will be supplied to such section further in the rear.

The system provided by this invention is adapted for use in track stretches which include intersections with highways since this sysern makes it. possible to employ steady energy to discontinue operation of a highway crossing signal without interfering with operation of the signals controlling movement of trains through the track stretch.

The system provided by this invention is arranged so that when steady energy is supplied to a track relay by any means other than the lockout circuit controlled by the track relay of the adjacent section in advance, or by the track relay to which the steady energy is supplied, the signal controlled by the track relay to which the steady energy is supplied will be conditioned to display its stop indication, while energy of the '75 code frequency will be supplied to the rails of the adjacent section in the rear.

Steady energy may be supplied to a track relay where back contact coding is employed at a cut section in a tra k circuit. Such a cut section may be required oecause of the length of signal block, or it may be installed to aid in the control of a highway crossing signal. One form of apparatus for providing back contact coding at a cut section is shown. in an application of B. Shields and Herman (3+. Blosser, Serial No. 275,146, filed May 23, 1939, for Railway traffic controlling apparatus, now U. S. Letters Patent 2,211,174, granted Aug. 13, 1M0.

Likewise, steady energy may be employed in a track circuit to control a highway crossing signal, as explained in the application of R. R. Kemmerer identified above.

For purposes of illustration it will be assumed that the section I2T is divided into two parts, that back contact coding equipment is located at the cut section, and that the equipment at the cut section operates when the forward portion of the track section is unoccupied to repeat to the rearward portion of the track section energy of the same code frequency as is supplied to the rails of the forward portion of the track section. The cut section facilities also operate when the forward portion of the track section is occupied to supply steady uncoded energy to the rails of the rearward portion of the section.

On passage of a train through. the track stretch, on entrance of the train into section lET the track relay EETR is shunted, and the contacts of the relays IZFSA and IZI-I are released, while the equipment operates as described above to supply energy of the '75 code frequency to the rails of section HT, and to condition the signal IZS to display its red or stop indication.

When the train enters the forward portion of section I2T the equipment at the cut section operates in the usual manner to discontinue the supply of coded energy to the rearward portion of the track section and to supply steady energy thereto.

As long as any portion of the train remains in the rearward portion of the track section, the track relay 12TH. is shunted and its contacts remain released. As soon as the train vacates the rearward portion of the track section, the steady energy which is supplied to the rails thereof by the cut section apparatus feeds to the track relay and causes the relay contacts to become picked up and remain picked up.

On picking up of the track relay contacts an impulse of energy is induced in secondary winding 2! of the decoding transformer, but at this time contact [6 does not establish the circuit of the winding 24 of relay l2FSA so that the contacts of relay IZF'SA remain released, and, as contact 25 of relay IZFSA is released, the circuit of the winding of relay IZIH is incomplete and the contacts of this relay remain released.

It will be seen, therefore, that on the supply of steady energy to the track relay IZTR. under the conditions outlined, the contacts of the relays I2FSA and 12H remain released, and thereby maintain the circuit for supplying energy of the 15 code frequency to the rails of section HT, while contact 34 of relay 12H maintains the circuit of the red or stop lamp R of signal I 2S.

As the train proceeds through the track stretch and enters the section in advance of the forward portion of the section I2T, the track relay for that section in advance is shunted and energy of the 15 code frequency is supplied to the rails of the forward portion of |2T so that when the train vacates the forward portion of section IZT, the cut section facilities operate in the usual manner to repeat the supply of energy of the 15 cod-e frequency to the rails of the rearward portion of section I2T.

As a result of the supply of coded energy to the track relay IZTR, the contacts of this relay become released to thereby supply an impulse of energy to the winding 2| of relay IZFSA, and on continued code following operation of the track relay contacts energy is supplied to the winding of relay I2H. Accordingly, the contacts of the relays IZFSA and IZI-I become picked up in the manner heretofore described in detail so that the signal I 28 is conditioned to display its yellow or caution indication, while energy of the I80 code frequency is supplied to the track transformer HTT.

Although I have herein shown and described only one form of railway signaling 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 scopeof my invention.

Having thus described my invention, what I claim is:

1. In a coded railway signaling system, in combination, a stretch of railway track having a pair of track rails divided by insulated joints into successive track sections including adjoining forward and rearward sections, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay having a winding receiving energy from the rails of said forward section, a transformer, a first and a second auxiliary relay associated with said track relay, means including a contact of said track re lay for varying the energization of the transformer primary winding in response to code following operation of the track relay, means operative when the track relay contacts are in their released position for supplying energy from the transformer secondary winding to a winding of the first auxiliary relay, a holding circuit operative when the contacts of the track relay and of the first auxiliary relay are picked up for supplying energy to a winding of the auxiliary relay to maintain the contacts of the auxiliary relay picked up, means responsive to continued code following operation of the track relay subsequent to picking up of the contacts of the first auxiliary relay for supplying energy to the winding of the second auxiliary relay, a first supply circuit for supplying coded energy to the rails of said rearward section, said first supply circuit including a back contact of one of said auxiliary relays, a second supply circuit for supplying steady energy to the rails of said rearward section, said second supply circuit being complete when and only when the contacts of the first auxiliary relay are picked up and the contacts of the second auxiliary relay are released, and a third supply circuit established on picking up of the contacts of the second auxiliary relay for supplying coded energy to the rails of said rearward section.

2. In a coded railway signaling system, in combination, a stretch of railway track having a pair of track rails divided by insulated joints into successive track sections including adjoining forward and rearward sections, means for at times supplying coded energy and at other times supplying steady energy to the rails of said forward section, a code following track relay having a winding receiving energy from the rails of said forward section, a transformer, a first and a second auxiliary relay associated with said track relay, means including a contact of said track relay for varying the energization of the transformer primary winding in response to code following operation of the track relay, means operative when the track relay contacts are in their released position for supplying energy from the transformer secondary winding to a winding of the first auxiliary relay, a holding circuit including front contacts of the track relay and of the first auxiliary relay and a back contact of the second auxiliary relay for supplying energy to a winding of the first auxiliary relay to maintain the contacts of said relay picked up, a circuit including front contacts of the track relay and the first auxiliary relay for supplying energy from the transformer secondary winding to the winding of the second auxiliary relay, the transformer and the second auxiliary relay being proportioned so that the relay contacts when released become picked up only after a plurality of impulses of energy have been supplied from the transformer to the relay winding, a first supply circuit for supplying coded energy to the rails of said rearward section, said first supply circuit including a back contact of one of said auxiliary relays, a second supply circuit for supplying steady energy to the rails of said rearward section, said second supply circuit being complete when and only when the contacts of the first auxiliary relay are picked up and. the contacts of the second auxiliary relay are released, and a third supply circuit established on picking up of the contacts of the second auxiliary relay for supplying coded energy to the rails of said rearward section.

CRAWFORD E. STAPLES.

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