US2607002A - Coded signaling apparatus - Google Patents

Description

Aug. 12, 1952 c. w. FAILOR CODED SIGNALING APPARATUS Filed June 20, 1946 2 SHEETS SHEET 1 INVENT R lzwr'les W (ZJZOP.

III

HIS ATTORNEY C. W. FAILOR CODED SIGNALING APPARATUS Adg. 12, 1952 2 SHEETS-SHEET 2 Filed June 20, 1946 INVENTOR D Em. uE. E z 9 6 08 ATTORNEY Patented Aug. 12, 1952 CODED SIGNALING APPARATUS Charles W. Failcr, Forest Hills, Pa assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application June 20, 1946, Serial No. 618,026

My invention relates to coded railway signaling apparatus and particularly to improved means for preventing improper supply of energy to a code following relay. r

In some types of coded signaling systems, as for example, a coded track: circuit signaling system, a transmitting relay is located at one end of a pair of conductors and has contacts which are operated between two positions in one of which they connect the winding of a code following relay across the conductors and in the other of which they connect a source of energy across the conductors.

The contacts of the transmitting relay are normally adjusted so that on movement of the relay movable contacts between their two positions, the circuits established in one position of the relay contacts are interrupted before the circuits established in the other position of the relay contacts are established.

If the transmitter relay contacts are out of adjustment, the circuits controlled in both'positions of the relay contacts may be established simultaneously during movement of the relay con-- tacts between their two positions and energy from the source may be supplied through the transmitter relay contacts to the winding of the code following relay and may pick up its contacts, while the supply of energy from the source to the wind ing of the code following relay may be interrupted when the contacts of the transmitter relay complete their movement. If energy is supplied from the source to the winding of the code following relay over the transmitter relay. contacts, the contacts of the code following relay will pick up and release and will cause energization of the code detecting relay governed thereby even though coded energy is not being supplied over the cone ductors to the code following relay.

An object of this invention is to provide improved means governed by the contacts of a transmitting relay for alternately connecting a source of energy and. the winding of a code fol- 6 Claims. (01. 246-48) of the movable contacts short-circuits the track battery and overlapping of the fixed contacts associated with-the other one of the movable contacts short-circuits the code following relay,

Another object of the invention is to provide improved means of the type described which employs two movable contacts of the transmitting relay which are connected together permanently and which control circuits arranged so that in one position of the transmitting relay contacts a code following relay is connected across the track rails and so that in the other position of the transmitting relay a source of energy is connected across the track rails independently of the winding of the code following relay. i

A further object'of the invention is to provide improved means of the type described which employs a first transmitting relay which has contacts movable between a first and a second position and governs a second transmitting relay to cause its contacts to occupy corresponding positions, and having circuits including two movable contacts of the second transmitting relay which are connected permanently together and meetfective in one position to connect a code following relay across the track rails and effective in the other position provided a contact of the first transmitting relay is in the corresponding position to connect a source of energy across the track rails independently of the winding of the code following relay.

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

I shall describe two forms of coded signaling apparatus embodying my invention and shall then point out the novel features thereof in claims.

In practicing my invention I provide a transmitting relay together with means for recurrently moving the relay contacts between their two positions. Two movable contacts of this relay are permanently connected in series and whenrboth movable contacts are in one position establish a circuit to connect a code following relay across the rails of a track section, while when both movable contacts are in their other position they establish a circuit independent of the winding of the code following relay to connect a source of energy across the track rails. These circuits are arranged so that, if one movable contact simultaneously engages both of the associated stationary contacts, the winding of thecode following relay will be short-circuited and so that, if the other movable contact simultaneously engages both of its associated stationary contacts, the source of energy is short-circuited to thereby prevent improper supply of energy from the source to the code following relay in the event that either of the contacts of the transmitting relay is defective.

In a modification, the transmitting relay is governed by an associated transmitting relay which also controls the circuit for connecting the source of energy across the track rails so that a short time interval is provided between the instant of interruption of the supply of energy from the source and the instant at which the circuit for connecting the code following relay across the track rails is completed.

In the drawings, Fig. l is a diagram of a section of railway track equipped with coded track circuit apparatus embodying this invention, and

Fig. 2 is a diagram of a section of railway track equipped with a modified form of coded track circuit apparatus embodying my invention.

Similarly reference characters refer to similar elements in each of the two views.

Referring to Fig. 1 of the drawings, there is shown therein a section of railroad track through which traffic normally moves in the direction indicated by the arrow, that is, from left to right. The locomotives which are operated in this track stretch are equipped with cab signal apparatus responsive to flow of coded alternating current energy in the track rails. The construction and operation or the locomotive cab signal apparatus is not a part of this invention and this equipment may be arranged as shown in Letters Patent of the United States No. 1,986,679, issued January l; .1935 to Lloyd V. Lewis for Railway Trafiic Controlling Apparatus.

The track rails l and 2 of the track section shown in the drawings are separated from the rails of the adjoining sections by insulated joints 3. A code following track relay TR is connected across the section rails at the left-hand or entrance end of the section and is operated by coded energy supplied over the section rails from the right-hand or exit end of the section. The track relay-TR controls a repeater relay TM, and it also controls an impulse relay IR which causes impulses of feed back energy to be supplied to the rails at the entrance end of the stretch.

An approach relay AR is located at the exit end of the section and the winding of this relay is connected across the section rails when the contacts of the transmitter relay CTM are released.

As shown, the track section is vacant and relay AR is released so energy is supplied over front contact iii of a continuously operating code transmitter CT and back contact 1 I of relay AR to the transmitter relay CTM and its contacts are picked up. The energy which is supplied to relay CTM is supplied from a suitable local source, such as a storage battery, not shown, the terminals of which are designated B and C in the drawings.

As the contacts of relay CTM are picked up, the track battery TB is connected across the section rails over the circuit which istraced from the positive terminal of the battery through the secondary winding of the track transformer T1, and over front contacts 14 and 15 of relay CTM in series to track rail i, while the negative terminal of the battery is connected directly to track rail 2. At this time, as the contacts of relay CTM are picked up, the circuit of the winding of relay AR is open at contact 15 of relay CTM so the relay AR remains released and its contact I I maintains thecircuit of the relay CTM.

The energy supplied from battery TB to the section rails feeds over the track rails and over back contact I6 of relay IR to the winding of the track relay TR and picks up its contact to interrupt the circuits of relays TM and IR so that they are released.

After a short time interval contact it of code transmitter CT interrupts the circuit of the relay CTM and its contacts release to interrupt the circuit traced above for connecting the track battery and the secondary winding of the track transformer across the track rails while the winding of relay AR is connected across the track rails over the circuit which is traced from track rail 1 through the winding of relay AR, and back contacts 15 and I4 of relay CTM in series to track rail 2.

When the supply of energy from battery TB to the section rails is cut oil, the track relay TR releases and energy is supplied over its 'back contact 8 to relay TM, and prior to picking up of relay TM, is supplied to relay IR over the branch circuit which includes back contact 19 of relay TM. The energy supplied to relay IR prior to pickingupof relay TM picks up the contact of relay IR, while the relay IR is snubbed by a rectifier so that the relay contact remains picked up for a short time interval subsequent to interruption of the relay circuit. When relay IR picks up, energy is supplied from the impulse battery IB through the winding of track relay TR in the wrong direction to pick up the relay contact.

The track relay 'IR and the approach relay AR are of the polar biased neutral type, the contacts of which-pick up when and only when energy flows through the relay winding in aselected direction as indicated by the arrow on the relay. As explained in Letters Patent of the United States No. 2,286,002, issued June 9, 1942 to Frank H. Nicholson for Railway Signaling System, this arrangement for supplying energy from battery IB through the winding of relay TR. protects this relay against improper energization in the event the front and back contacts of relay IR overlap, and also protects the relay TR against operation by energy inductively discharged from the track circuit on interruption of the circuit of the battery IB.

When relay IR picks up and connects battery IB across the section rails, energy from the battery is supplied over the section rails and over back contacts l4 and [5 of relay CTM to the winding of relay AR and picks up the contacts of the. relay AR. On release of relay IR, the supply of energy from the battery IE to the relay AR is cut off and relay AR releases and closes its back contact I l in the circuit of relay CTM so that energy is supplied to relay CTM during the next closed period of contact H] of the code transmitter CT.

The contact ill of the code transmitter CT continuously operates between its two positions at a predetermined rate, such as 75 or times a minute so it is closed shortly alter release of relay AR. Accordingly, energy is supplied to re lay CTM and its contacts pick up to interrupt the circuit of relay AR and connect the track battery and the secondary winding of the track transformer TT across the section rails with the result that energy from the battery feeds to the track relay TR and picks up its contact i8. When the track relay TR icks up, the supply of energy to relay TM is interrupted and its contacts release. A resistance is connected acrossthe terminals of the winding of relay TM and, .on interruption of the 'supply'of energy to the relay winding, delays release of. the relay contacts slightly to compensate for the delay in picking up. of the relay contacts on the supply of energy to the. relay winding and thereby substantially;'equalizes the picked-up andreleased periods ofithe contacts of the relay 'IM.:,

After a short interval, contact I of the code transmitter CT interruptsthe circuit. of the relay CTM and its contacts release to cut off the'supply of energy from battery TB torelay TR and the contact of relay TR releases to establish the circuits of relays TM and IR so that the contact of relayIR picks up to cause an impulse of energy to be supplied from battery IE to the relay AR.

As long as the section is vacant, the equipment continues to operateas described and as'a result of movement of the contacts of relay TM energy is supplied through the decoding transformer DT to the relay H and its contacts are picked up. The relay H may be employed-for any suitable purpose, such as to control a signal, not shown, for governing movement of traflic in the stretch. Likewise, movement of the contacts of the relay AR causes energy to be supplied through the decoding transformer ADT to relay AH and its contacts arepicked up with the result that its contact 20 short-circuits the primary winding of the track transformer TI. The relay AH is provided with other contacts which control circuits which may be employed for any appropriate purpose. 7

When a train enters the section, the track rails are shunted and energy supplied from battery TB ceases to operate relay TR and it remains released sorelay TM is steadily picked up while relay IR remains released and does not supply energy from battery IE to the section rails. Accordingly, relay AR remains released andits contact II maintains the circuit of relay CTM and relay CTM continues to be operated by the.

code transmitter CT.

is no longer supplied through the decoding transformer DT to relay H and its contacts release. Similarly, when relay AR remains released, energy is not supplied through transformer ADT to relay AH and its contacts release so that contact 20 establishes the circuit for supplying alternating current energy to the primary winding of track transformer TT froma source the terminals of which are designated BX and CK. Accordingly, during the pick-up periods of the relay CTM, alternating current energy is supplied from the secondary winding of the track transformer T1 to the section, rails and operates the locomotive cab signal equipment.

When the section is vacated, energy supplied from battery TB to the section rails again operates the track relay TR while relay IR again operates to supply energy from battery IE to the relay AR. As a result of operationfof relay TR the relay H picks up, and as a result of operation of relay AR the relay AH picks up to interrupt the supply of energy to the primary winding of transformer TT and to short-circuit this winding.

This equipment is arranged so that if the contacts of relay CTM are out of I adjustment,

with the result that either of the movable contacts I4 and I5 engages its front and its back points of contact simultaneously, energy will'not be supplied from'battery TB or from the track transformer TT to the relay AR.

6 tTsIf contact I4engages its front and backpoint's of contact simultaneously,'the track battery and the secondary windingof the transformer TT are short-circuited over the circuit which is traced from the positive terminal of the battery through the transformer, secondary winding, and" thence to the negative terminal of the battery through front and, back points of contact of contact. I4, which are assumed to overlap orengage. the battery and transformer are short-circuited,- en,- ergy will not be supplied to relay AR regardless of the position of contact I5, and there is. no danger that the contacts of relay AR will be picked up and released because of the supply of energy to the relay winding from the battery'I'B or the transformer I g If contact I5 engages its front and back points of contact simultaneously, the winding of relay AR is short-circuited through the contact I5, as is obvious-from the drawing, and the relay AR will not be operated by energy supplied from battery TB or the transformer TT. I v

If the contacts I4 and I5 are out ofadjustment so that front contact I4 and back contact I5 engage simultaneously, energy may be supplied from the battery TB and the transformer TT through the winding of relay AR to the track rails. However, the energy supplied from the battery flows through the winding of relay AR in the wrong direction to pick up the relay contacts. The alternating current energy supplied from transformer TT to the winding of relay AR is of relatively high frequency, and the contacts of relay AR may not operate rapidly enough to respond to' this energy, but if they do, the rate of operation of the contacts is so high that too.

little energy is supplied through the decoding transformer ADT to relay AH to pick up the relay contacts or to maintain them packed up.

Accordingly, relay AH is released under thesev conditions.

.If the contacts I4 and I5 are out of adjustment so that back contact I4 and front contact I 5 engage simultaneously, the back rails I and 2 are short-circuited and the relay AR isv certainv to' remain released. The circuit of the relay AR is arranged so that energy inductively discharged from the track circuit on interruption of the circuit of the track battery will not, pick up the contacts of the relay AR. When the contacts of relay CTM are picked up, the battery TB is connected across the track rails with the positive terminal of the battery connected to track rail I so that energy flows from the battery to track rail I, thence to trackv rail 2 and the negative terminal of the battery through the winding of track relay TR, on through the wheels and axles of a vehicle. if the section is occupied. Because of the inductance of the track circuit, an impulse of energy is in duced in the trackcircuit when the supply of energy from the battery to the track rails is interrupted by opening of front contacts I4 and.

I 5 of relay CTM, and, on closing of back contacts I4 and I5 of relay CTM, this energy is supplied to the. winding of relay AR. The energy supplied at this time flows in the same direction as that supplied from the battery, and therefore flows from track rail I to track rail 2, over back contacts I4 and I5 of relay CTM and through the winding of relay AR from right to leftto track rail I. This impulse of energy, therefore, flows through the winding of relay AR in the wrong direction to pick up the relay contacts. so. there is .no possibility that the relay contacts will be improperly picked :up by the energy inductively discharged from the track circuit.

. As a result of the supply of energy from the track battery TB to the track rails, a charge may .be built up in the track ballast so that the ballast and the track rails together in effect form a storage battery from which energy may be supplied to the winding of the relay AR when the relay winding is'c'onne'cted across the track rails. However, the voltage of the energy supplied from this source to the relay AR is relatively low and although this energy flows through the winding of relay AR in the proper direction to pick up the contacts of relay AR, insufficient energy flows through the winding of relay AR to pick up the relay contacts, and the relay contactswill not be picked "up improperly by energy supplied from this source.

It willbe seen, therefore, that the track battery and track transformer and the relay AR are alternately connected across the section rails by contacts of the transmitter relay CTM, but that the connections governed by the contacts of the relay CTM are arranged so that, in the event the contacts of relay CTM are out of adjustment, there is no possibility that the relay AR will be operated by energy from the battery TB or the transformer TT so as to improperly energize the relay AR. Similarly, the various parts of the track circuit are arranged so that the contacts of relay AR will not be improperly picked up by energy'inductively discharged from the track circuit or by energy stored in the track circuit. Accordingly, the relay AH is certain to remain released unless the relay AR is being operated by coded energy supplied over the section rails and the relay AH, therefore, reliably indicates whether the section is occupied or not.

The arrangement provided by thisinvention is also adapted for use in track sections where feed-back energy of both polarities is employed and Fig. 2 is a diagram showing this modification. The apparatus of Fig. 2 is generally similar to that shown in Fig. 1 but differs therefrom in that two code following approach relays are provided at the exit end of the section. These relays are designated ARN and ARR and are of the biased polar type, like relay TR, but are arranged so that they respond to feed-back energy of opposite polarities. In addition, a repeater relay CTMM is provided for the transmitter relay CTM to provide an open circuit interval following interruption .of the circuit of the track battery TB and thus prevent operation of either of the approach relays byenergy inductively discharged from the track circuit.

At the entrance end of the section, a pole changing relay PC governs the polarity of the energy supplied from the battery IE to the track rails, while a repeater relay IM is provided for the. impulse relay IR to provide an open circuit interval following interruption of the. circuit of the batteryIB and thus prevent operation of the track relay by energy inductively discharged from the track circuit. The relay PC may be controlled in any suitable manner, not shown, as, for example, by traihc conditions in the section tothe left of the section shown.

The apparatus of Fig. 2 is shown in the condition which it assumes when the track stretch is vacant and an impulse of energy is'being supplied from' the track battery to the track relay. At this time contact of the code transmitter CT is closed and supplies energy to the transmitter relay CTM and "its contacts are picked up with the result that energy is supplied over its front contact :25, back contact 26. of relay ARR, and back contact2] of relay ARN to relay CTMM and its contacts :are picked up. As relays CTM and CTMM are picked up, the track battery TB and track transformer TT are connected across the track rails over the circuit which is traced from the positive terminal of the battery through the secondary winding of transformer 'IT, over front contact 38 of relay CTM, and front contacts 3| and 32 of relay CTMM in series to track rail I, while the negative terminal of the battery is connected directly to track rail 2.

The energy supplied from battery TB to the track rails is supplied to the winding of track relay TR over the circuit which is traced from track rail 1 through the track relay winding from left to right, back contact 35 of relay IR, and back contacts 36 and 31 of relay IM in series to track rail 2. The energy supplied to the track relay TR picks up its contact I8 to interrupt the circuit of relay TM and of relays IR and IM and these relays are released.

After a short time interval th contact 19 of code transmitter CT opens and opens the circuit of relay CTM and its contacts release so that contact 25 interrupts the circuit of relay CTMM while contact 38 interrupts the circuit of the battery TB and of the track transformer TT. The relay CTM is snubbed by a rectifier and resist: ance so release of the relay contacts is delayed slightly after interruption of the circuit of the relay winding to compensate for the pick-up time of the relay and thus equalize the pickedup and released times of the relay contacts. The relay CTMM is also snubbed by a rectifierand a resistor so the contacts of this relay do not release for a short period after the supply of energy to the'relay winding is interrupted by release of contact 25 of relay CTM.

In the period between release of relays CTM and CTMM the track rails are short-circuited over the circuit which is traced from track rail I over front contacts 32 and 3! of relay CTMM in series and back contact 30 of relay CTM to track rail 2. This short-circuiting of the track rails discharges energy stored in the track ballast and also dissipates the energy impulse induced in the track circuit on interruption of the circuit of the track battery and prevents this energy impulse from being supplied to the relays ARN and ARR. Where only one approach relay is employed, as in Fig. 1, the equipment can be arranged so that the impulse of energy inductively discharged from the track circuit is of the wrong polarity to operate the approach relay, but where two approach relays, which are responsive to energy of opposite polarities are employed, this method of protecting the approach relays cannot be employed and the time interval provided by the relay CTMM is provided for this purpose.

When the supply of energy from battery TB is cut off, the track relay TR releases and energy is supplied over its back contact 18 to relay TM, and is also supplied over back contact 19 of relay TM to relay IR, and, in addition, over back contact 39 of relay IR to relay IM. The supply of energy to relays IR and IM is cut off as soon-as relay TM picks up but the apparatus is arranged so the relays IR and IM will be picked up by the energy supplied thereto prior to picking up of relay I'M. After relay IR picks up, energy is supplied to relay IM over the front contact 39 of relay IR so the relay IM will remain picked up as long as relay IR is picked up. The relay When relays IR and IM are both picked up,

the battery IB is connected across the track rails so as to supply energy of normal or reverse polarity according as the contacts of relay PC are picked up or released. As shown, the contacts of relay PC are picked up and when relays IR and IM are both picked up, the positive terminal of battery IB is connected over front contact 40 of relay PC, front contact 4| of relay IR and front contacts 3'! and 3-6 of relay IM in series to track rail I, while the negative terminal of the batteryis connected over/front contact 42 of relay PC to track'rail 2. The energy supplied from battery IE to the track rails is supplied to relays ARN and ARR in series over the circuit which is traced from track rail I through the winding of' relay ARN from left to right, over back contacts 32 and 3| of relay CTMM in series, and through the winding of relay ARR from left to right to track rail 2. l

The energy supplied from battery 13 when relay PC is picked up is of the polarity eifective to pick up the contacts of relay ARN but not relay.

ARR. When relay ARN picks up, its contact 21 interrupts the circuit of relay CTMM to insure that relay CTMM remains released and maintains the circuit of the relays ARN and ARR. As relay CTMM cannot pick up when relay ARN or relay ARR is picked up there is no possibility that relay ARN or ARR, when picked up, will be released as a result of picking up of relay CTMM. Accordingly, if foreign current is present and picks up one of the relaysARN or ARR, the relay will be steadily picked up and will not cause energy to be supplied through the associated decoding transformer, as would occur if the relay were recurrently released because of picking up of relay CTMM. The relays ARN and ARR, therefore, will not operate as code following relays if foreign current is present and the relays AHN and AHR will both be released.

When relay ARN or ARR is picked up, the circuit of the relay CTM is not affected and it continues to be operated by the code transmitter CT. However, picking up of relay CTM does not affect the circuit of the relays ARN and ARR, and picking up of relay CTM with relay CTMM released does not result in the supply of energy from the track battery TB or the track transformer to the section rails.

Returning to the equipment at the entrance end of the section, the relay IR releases after a short interval and its contact 4| interrupts the circuit of battery IB and its contact 39 interrupts the circuit of relay IM, but the snub for relay IM delays release of its contacts for a short interval. After release of relay IR, but before release of relay IM, the track rails are shortcircuited over the circuit which is traced from track rail l over front contacts 36 and 31 of relay IM in series and back contact 4| of relay IR to track rail 2. The short-circuiting of the track rails discharges energy stored in the track ballast and it dissipates the impulse of energy inductively discharged from the track circuit on interruption of the supply of the circuit of battery IB and thus prevents picking up of the contact of relay 10 TR by this energy. Where the energy supplied from battery IB tothe section rails is always of the same polarity, the arrangement shown in Fig. 1 may be employed to prevent picking up of the track relay by energy inductively discharged from the track circuit, but where the energy supplied frombattery IB is at times of one polarity and at other times of the other polarity, the arrangement shown in Fig. 2 mustbe employed.

The relay IM releases shortly after reIayIIR and interrupts the circuit traced above for shortcircuiting the track rails and establishes the previously traced circuit for connecting the track relay TR across the track rails.:

- When the supply of energy from battery 13 is cut off, the relay ARN releases and its back contact 21 is closed to permit energy to be supplied to relay CTMM. 1

On subsequent closing of contact I0 of the code transmitter CT,,.energy is supplied to relay CTM, and prior to picking up of relay CTM, is also supplied torelay CTMM over back contact 25 of relay CTM so that relay CTMM will pick up concurrently with relay CTM. When relay CTM picks up, its contact 25 establishes a circuit for energizing relay CTMM to keep it picked up as long as relay CTM is picked up. When relays CTM and CTMM are picked up, energyis again supplied from the battery TB over the section rails to relay TR and its contact I8 is picked up to release relay TM, while the equipment thereafter operates as previously described,

As a result of operation of relay TM energy is supplied through the decoding transformerDT to the relay H and its contacts are picked up. Similarly, as a result of operation of relay ARN energy is supplied through the transformer NDT to relay AHN and its contacts are picked up. with the result that, the primary winding of transformer TT is, short-circuited over the circuit which includes back contact 45 of relay AI-IR and front contact of relay AHN.

On the approach of a train. the contacts of relay PC may be released by means not shown, thereby changing the polarity of the energy supplied from battery IB. After release of relay PC the positive terminal of battery '13 is connected over back contact 42 of relay PC to track rail 2, While during the picked-up periods of r'elaysIR and 1M the negative terminal of the battery is connected over back contact All of relay PC, front contact 4| of relay IR, and front contacts Hand 36 of relay IMin series to track rail I. The energy supplied -from battery IB at this time flows from rail 2 through the winding of relayARR from right to left, over back contacts 3| and 32 of relay CTMM in series, and through the winding of relay ARN from right to left to track rail I. This energy, therefore, is effective to operate relay ARR but not relay ARN, and as a result the relay AHR is picked up while relay AHN releases. After relay AI-IR picks up, the primary winding of transformer TT is short-circuited over front contact 45 of relay AHR, while they operation of the equipment is otherwise unchanged.

When the train enters the track section shown, the track relay TR is shunted and remains released and establishes the circuit of the relay TM so that its contacts are steadily picked up and energy is no longer supplied to relay H and it releases while contact IQ of relay TM interrupts the circuits of the relays IR and IM and they remain released so that energy is no longer supplied from battery IE to the section rails and relaysARN and ARR both remain released. Accordingly, relay AHR, releases and relay AI-IN remains released and energy is. supplied over back contact 46 of relay AHN and back contact 4-5. of relay AHR to the. primary winding of track transformer 'IT. so. that during subsequent picked-up periods of the relays CTM and CTMM alternating current energy, is. supplied from the transformer secondary winding to. the track rails to operatethe cab signal apparatus on the locomotive in the track section.

When the section is vacated, energy frombattery TB again feeds to track relay TR and picks up its contact [8 and relay TM release so that on subsequent release of relay 'IBenergy is supplied over back contact if of relay TM to relays IR and IM'and they pick up to. supply energy from battery IE to the section rails. This energy picks up one or the other-oi the relays ARN or ARR, depending on the polarity of the energy, with the result that one of the relays AHN or AHR. picks up to. cut off the supply of energy to transformer TT and to short-circuit the transformer primary winding. Similarly, as a result ofoperation of the track relay TR, the relay I-I picks up and the equipment is again substantially in the condition in which it is shown in the drawings.

This equipment is arranged so that defects in the contacts. of relays CTM, and CTMM, or abnormal operation of these contacts, cannot result in objectionable supply of energy from the battery TB. or the transformer IT to the relays ARN and ARR, or in picking up of either of the relays ARN or ARR by the energy inductively discharged from the track circuit on interruption of the circuit of the track battery.

If the front and backpoints of contact or" movable contact 38 of relay CTM engage simultaneously, the track battery TB and the primary winding of the track transformer T1 are shortcircuited and. energy will not be, supplied to. the relays ARN and ARR even if'the contacts of relay CTMM are released.

If front contact 30 of relay CTM is closed and contacts 31 and 3-2 of relay CTMM are released, energy cannot be supplied from the battery TB and the transformer TT to the relays ARN and ARR since the circuit of the battery and transformer is open at front contact 3| of relay CTMM.

If movable contact 3| of relay CTMM engages its front and back contacts simultaneously, a

circuit will be established from battery TB and,

transformer TT through the winding of relay ARR. during the picked-up periods of contact 38 of relay CTNL, At such times energy may be supplied from the positive terminal of the battery TB through the secondary winding of trans.- former TT, over front. contact 38 of relay CTM, through. front and back points. of contact of con.- tact 3i or relay CTMM, which. are assumed to engage simultaneously, and through the. winding of relay ARR from leftto right to the negative terminal of the battery. The energy supplied. from the battery to the winding of. relay ARR. flows through the relay winding in the wrong direction to pick up the relay contacts so they remain released and. this supply of energy to relay ARR cannot produce an objectionable result. If energy is supplied from transformer IT to relay ARR, over the circuit traced above, the. relay contacts, if they operate. at all, will operate so rapidly that insufiiciently energy will be supplied through the transformer EDT to r'elay AHR to pick up its contacts.

Under the conditions stated namely, when the front and back contacts of contact 3;! engage simultaneously, if back contact 32 is closed, energy may be supplied from battery: TBv and transformer T1 through the winding of relay ARN to the track circuit. This will also be true if the contacts of relay CTMM' are out or adjustment so that front, contact 3i and back contact 32 engage simultaneously. At. such times the positive terminal of the battery TB is connected through the secondary winding of trans-V former TT, over front contact 33 of relay CTM, front ccntact 3;! back contact 3-2 of relay CTMM, and through the windingof relay ARN from right to left to track rail l, while the negative terminal of the battery is connected to track rail 2. The energy supplied from the battery through the winding of relay ARN flowsthrough the relay winding in the wrong direction to pick up the relay contacts and there is no danger that relay ARN will be operated improperly. As explained above, energyirom thetransformer TT may be supplied through the winding otrelay ARN but cannot cause energizationof relay Ali-1N.

If the front and back points of contact of movable contact 312 engage simultaneously, the

winding of relay ARN will be short-circuited and energy will not be supplied through this winding regardless of the position of contact at of relay C'IMM or contact tllcf relay CTM. Ac cordingly, the contacts of relay ARN remain released and will not cause improper energizetion of relay AHN. r

If front contact 32 and back contact iii of relay CTMM engage simultaneously, the relay ARR, will be connected across the track rails,

but the circuit of the battery TB and; of the transformer TT is open at front contact 3;! of relay CTMM and energy will not be supplied from the battery or the transformer to, either the relay ARR or the track circuit and relay ARR remains released, while, the circuit of the winding of relay ARN is open at, back contact 32 of relay CTMM and relay- AR-N remains released.

The equipment at the exit; end of the section is also arranged; so that the;- impulse of energy induced in the track circuit on interruption of the, circuit of the-battery 'IBwill not; be supplied to relay ARN or ARR. and will notoperate their contacts. Energy is supplied from battery '13)?-v to the track rails only when relays- CTM and- CTMlVl are both picked up, and when relay EZ'IIM is picked up its contact 2% establishes: a circuit for relay C'Im so that the contactsof relay CTMM remain picked up as lon as relay CFIM is picked; up. On interruption cfthe circuit of the relay CTM by contact 1a of the code transmitter CT the contacts of relay- CTM release with the, result, thatcontact; Siliinterrupts the circuit or" battery TB and contact. 2-5. interrupts the circuit of the relay CTMM; but, becauseof; the rectifier and resistance snub, connected across the terminals of the winding'of relay CTMM', the

CTM, e: now. f ene y: the. r ck: c r uit ceases and an impulse of energy is induced the track circuit. When contact 3;") of relay CTM engages its. back contact, the contacts of relay relay TR. If movable contact 4| of relay IR,

engages its front and its back points of contact simultaneously, the battery IB will be shortcircuited and energy will not. be supplied from the battery to either thetrack relay or the track circuitand the contact ofthe track relay will remain; released and maintain the circuit of the relay TM so that relay I-I remains released. H

v If front contact 4| and backcontact 35, of relay IR are closed simultaneously, energy will not be supplied from battery IE to relay TR as,

the circuit of relay IR is open at back contact 36 of relay IM, if the contacts of relay IM are picked up, or at front contact 31, if the contacts of relay IM are released. v r v If movable contact 31 of relay IM engages its front and back points of contact simultaneously, the battery IE will be short-circuited when contact 4! of relay IR is picked up and energy will not be supplied from the battery 13 to the relay TR regardlessof the position of contact 36 of relay IM or contact 35 of relay IR.

Similarly, if movable contact 36 of relay IM engages its front and back points of contact simultaneously, the winding of relay TR will be' short-circuited if back contact 35- of relay IR is closed to establish the circuit of this winding. As the winding of the track relay is short-circuited the relay contact is certain to remainreleased.

As was explained in detail above the relays IR and IM cooperate to prevent energization of relay TR by the impulse of energy inductively discharged from the track circuit on interruption of the circuit of the battery 113.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood vthat variouschanges,

,50 the scope of the appended claims without departing from the spirit and scope of my invenand modifications may be made therein within tion.

Having thus described my invention, what I claim is:

1. In combination, a first and a second conductor extending between two spaced locations, and apparatus at one of said locations, at least, for alternately supplying coded energy to said conductors and for receiving coded energy from said conductors comprising a transmitter relay having a'first and a second movable contact which are connected directly together and are moved periodically between a first and a second position substantially in synchronism, a code following relay having one terminal of its winding connected permanently to said first conductor and having a contact biased to a first position and movable to a second position when and only when energy is received from said conductors which flows through the relay winding in the positive to negative direction from said first conductor to said second conductor, a source of direct current energy having its negative terminal permanently connected to said second conductor, said transmitter relay first movable contact being effective according as it is inv itsfirst' or its second position to connect said transmitter relay second movable contact to said second con-' ductor or to the positive :terminalyof said source of direct current, said, transmitter relaysecondmovable contact being effective. accordingas-it is in its first or its second position t connectsaid transmitter relay first movable contact to the other terminal of the winding of said code following relay or to said first conductonand a detector relay responsive to the periodic movefollowing relay ment of the contact of said code between its'two positions.

, 2. In a coded signaling system,

a first and a second location, a first code following relay at said first location responsive to direct current impulses received over said conductors, a first source, of direct current at said first location for supplying impulses to said conductors during the intervals between the received impulses, said first source having its positive terminal connected to the first conductor, a second code following relay having one terminal connected perma-- nently to said first conductor and a second source ofv direct current having one terminal connected permanently to said second conductor, both atsaid second location, a transmitter relay at said second location having a first and a second -mov-' able contact which are electrically connected to-- gether. permanently and are moved periodically between a first and a second position substantially in synchronism, a circuit including both of said transmitter relay contacts in series for connecting the winding ofsaid second code fol- I lowing relay across said conductors when both of said transmitter relay contacts are in the'irfirst position, a circuit including both of said transmitter relay contacts in series forconnecting'said second source of direct current across said conductors with the positive terminal of said sec-'- ond source connected to said first conductorwhen both of said transmitter relay contacts arein their second position, said second code following relay having a contact biased to a first position and movable therefrom to a second position when and only when current flows in the positiveto negative direction through the relay winding from the terminal which is connected to said first conductor to the terminal which is connected to said second conductor, and a code detecting relayresponsive to code following operation of said second code following relay.

supplying coded energy to said track rails and for receiving coded energy from said track rails,

comprising a first transmitter relay having contacts which are moved between a first and a sec?" ond position, a second transmitter relay havin'g' a first and a second movable contact whichare; electrically connected together and are movable' in combination, a first and a'second conductor extending between 3. In a coded track circuit signaling system, in combination, a section of railway track having a pair of track rails, and apparatus for alternately nately supplying coded energy of. a given relative.

polarity to said track railsandcforreceiving coded energy of either of two polarities from the track rails, comprising a first transmitter relay having contactswhich are moved. between a first and a second position, a second transmitterrelay having 7 a first and a second movable contact which. are electrically connected together and are movable periodically between afirst and a second position. substantially insynchronism, circuit means governed by said first transmitter relay for operatingthe, second transmitter relay to-cause its contacts to occupy their. first or their second. position according as the contacts of the first transmitter relay occupy their first or their secondposition, said first movable contact being effective according as'it is in its first or its second position to connect said secondmovable contact to'one of said track rails directly or through the winding of a first code followingv relay which is-responsive to energy of one polarity only, said. second movable contact beingcefiective according as it is in its second or its first position to connectv said first movable, contact, to the other of said track rails through the winding of a second code following relay or through asourcc of. energy provided a contact of saidfirst transmitter relay is in itsfirst position, said. code following relays eachhaving contacts biased to a released position and movable therefrom to a picked-up position. when and only when energy fiowscthrough the relay winding in a selected direction, the circuits for connecting said code following relays and said. source across the track rails being arranged; so

thatthese relays respond to opposite polarities of energy supplied overthe track circuits and so that theenergy supplied from said source to'the track rails is of the same polarity as that which is efiective to pick up the'contacts of said second codefollowing; relay. 1

5; In a coded track'circuit signaling system, J

in combination, a section-of'railway track having a pair of track rails, and apparatus for alternately supplying-coded energy to said track rails andfor receiving-coded energy from saidtrack rails, comprising afirst transmitter relay having contacts which are moved between a first and a second.

position, a second transmitter relay having a first and a second movable contact which are electrically connected-together and are movable periodically between a'first and a second position substantially in synchronism, circuit meansgovrelay occupy their firstlor their second position,

said first movable. contact being effectiveaccord ing as it is in its first or its second position to connect said second movable contact to one of said track rails directly or through the winding of a code following. relay, said second movable contact being efiective when in its first position to connect said first movable contact to the other of said. track rails through a source of energy provided a contact'of said first transmitter relay is in its first'position and-being effective when in its second position to establish a connection between said first movable contact and said other track rail irrespective of the position of the con-- tacts of said first transmitter relay.

6. In a coded track circuitsignaling system. in combination, a section of railway track having apair oftrack rails; andapparatus for alternately supplying coded energy to said conductors and for receiving coded energy from said con- 25:

ductors, comprising a first transmitter relay having contacts which are moved between a first and a second position; a second transmitter relay having a; first and-a second movable contact which are electrically connected together and are movable periodically between a first and a second posi-- tion substantially in synchronism, circuit means governed by said first transmitter relay for oper-' ating the second transmitter relay to cause its contacts to occupy their first or their second position according as the contacts of the first transmitter relay occupy their first or their second position, acode following relay having the first terminal of its winding connected to one of said track rails, said first movable contact being efiective according as it is in its first orits sec ond position to connect said second movablejcontact to said one track rail or'to the second terminal oi the Winding of said" code following relay, saidsecond movable contact being efiective when in its first positionto connect said first movable contact to the other of said track rails through a source of energy provided a contact of said first transmitter relay isiin its first position, saidsecond rnovable contact being effective when in itssecond position to establish a connection from said. first movable contact to-said other track rail irrespective of the position-of thecon tacts of said first transmitter relay. 1

CHARLES W.FAILOR;

err cannons orrnn Thedollowing-refrences are of record'in the file ot this patent:

UNITED STATES PATENTS

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