US2274283A - Railway signal system - Google Patents

Description

H. A. THOMPSON RAILWAY SIGNAL SYSTEM Filed April 17, 1940 Febf24, 1942.

Patented Feb. 24, 1942 2,274,283 RAILWAY SIGNAL SYSTEM Howard A. Thompson, Edgewood, Pa., assignor lto The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Appiication April 17, 1940, serial No. 330,122

(c1. 24e-3s) 12 Claims.

My invention relates to a railway signaling system, and particularly to improved means for extending the control of the signals to provide increased braking distance without` increasing the distance between adjacent signals.

It is an object offthis invention to provide an x improved signaling system employing the standard coded `signaling apparatus together with means to employ steady or uncoded energy for detecting the presence of a train in an overlap section.

A further object of the invention is to provide` lan improved signaling system arranged to insure that there is always an unoccupied space` ofat least a minimum distance in advance of the point at which the stop or most restrictiveindication is given toa following train. l

Another object of the invention is to provide an improved signaling system which operates to provide two different proceed indications, and( which makes it possible to obtain substantially the same close spacing of trains as is obtained where signaling systems capable of displaying a larger number of different proceed indications are employed.

A further object of the invention is to provide an improved signaling system having block sections divided into two track sections, and arranged so that there is always at least one such track section which is vacant in advance of the point at which a stop or the most restrictive indication is given tc a following train. n'

Other objects of the invention and features of* shown. These have four track sections which are designated AIIT, BIIT, AI2T and BI2T, while portions of two other block sections are shown and are designated Bl 0T and AIST.

Each block section has at the entrance end thereof a wayside signal designated S together novelty will be apparent from the following dei scription taken in connection with the accomif panying` drawing. v

I shall describe one form of improved signaling systemembodying my invention and shall then `point out lthe novel featuresthereof in claims.

`In the drawing, Fig. 1 is a diagram of a stretch of railroad track equipped with signaling appa- Aratus embodying my invention, and

Figs. Zand 3 are diagrams showing the types of energy suppliedv to successive track circuits `under different conditions of track occupancy.

Referring `to Fig.' 1 of the drawingthere is shown thereina stretch of railway track having `track rails I and 2 over' which trai-lic normally moves in the directionu indicated by the arrow,

lthat is, from left to right.

The rails of thetrack stretch are divided by yellow or-caution lamp Y, and a red with a prex corresponding to that of the block section with which the signal is associated. -As shown the signals are of the familiar color light type each having a green or clearlamp G, a or stop lamp R. l

It is to be understood that the invention is not limited to a system employing wayside signals of this type, but that any appropriate type of signals may be employed. Similarly the invention is not limited to' use on track stretches employing wayside signals, and is peculiarly applicable to track stretches in which cab signals only are employed., Y

vThe track rails of each of the track sections form a part of a track circuit to which alternating current is supplied at the exit end of the section from `the secondary windings of a track transformer TT. The circuits of the transformer secondary windings include the usual current limiting reactors 6.

The alternating current employed in the track circuits may be supplied from any suitable source, and may be distributed throughout the track stretch by a transmission line, not shown. The terminals of the source of alternating current are designated BX and CX in the drawing, while it will be assumed that the alternatingcurrent has a frequency of 100 cycles per second.

Each of the track sections has at the entrance end thereof a code following track relay TR having a winding receiving energy from the rails of the section through a resonant rectifier unit RU.

The resonant rectier units RU each comprise a transformer, a reactorand a capacitor arranged and proportioned so as to freely pass 100 cycle alternating current energy, and so as not to pass energy of a different frequency. Each of the resonant units includes, -in addition, a rectifier which converts into direct current the alternatingtcurrent energy which is supplied through the uni The track section at the rearward or entrance end of each block section has an auxiliary or second track relay TRA having a winding which is connected in series` with the winding of the code following or first track relayA TR. i

The code following track relay TR for the sec- .,tion at the entrance end of .each block section has associated therewith decoding means comprising a decoding transformer DT and auxiliary relays H and J.

The decoding means is not a part of this invention and any suitable apparatus may be employed for this purpose. The decoding means illustrated is shown and claimed in application Serial No. 210,744, of Frank H. Nicholson and Leslie R. Allison, filed May 28, 1938, for Railway traffic controlling apparatus.

As hereinafter explained the relays H and J cooperate to control the circuits of the lamps of the associated wayside signal, while the relay H and the track relay TRA cooperate to control the supply of `energy to the rails of the adjacent section in the rear. In addition, the relay H controls a circuit for at times short circuiting the winding of the auxiliary track relay TRA.

The signaling system shown in the drawing makes use of track circuit energy coded at two different frequencies. This coded energy is provided by code transmitters CT having two circuit making and breaking contacts 'I5 and ISB which are-continuously actuated 'by a motor or other suitable apparatus. The rate of operation of these contacts is such as to provide '75 and 180 energy impulses per minute which are separated by periods of equal duration during which no energy is supplied.

The track relay TR of the track section at the entrance end of leach block section has associated therewith a source of direct current, such as a primary or storage battery, not shown, the terminals of which are designated B and C in the drawing.

The equipment is shown in Fig. 1 in the condition which it assumes when the track stretch is Vacant. At this time the equipment, not shown, associated with section AIST operates, as hereinafter explained in connection with the equipment associated with section AI2T, to supply energyof the 180 code frequency through the track transformer BIZTT to the rails of section BI'ZTy with the result that the relay BIZTR responds to coded energy.

During the released periods of the contact 2B of track relay BIZTR the circuit 'for supplying energy to the primary winding of track transformer AIZTT is established, while this circuit is interrupted during the picked-up periods of the track relay contact so that the energy supplied to the transformer AIZTT is coded or interrupted -at the same frequency as the energy which is supplied tothe track relay BI ZTR.

Energy supplied to the rails of section AI2T feeds through the resonant rectifier unit AI2RU to the winding of relayAI2TR and produces code following operation of the relay contacts. cording-ly contact 2I of relay AI'ETR alternately establishes the'circuits for energizing the upper and lower portions of the primary Winding 22 of the `decoding transformer AIZDT, while as a result of this energization of the two portions of the primary winding 22 current is induced in thesecondary windings 23 and 24. The Contact 25 recties the current supplied from the winding 24 to the winding of the relay AIIfH with the result that the contacts of the relay AI2H are picked up.

As the track relay AIZ'IR is responding to energy of the 180 code frequency, ythe frequency of the energy inducedj in the winding 23 is such that it is freely passed by `the resonant rectifier unit,Al2R UAfand suici'ent y.energy is supplied to the winding of relay AI2J to pick up the contact of this relay.

As contact 2l of relay AI2H is picked up, a circuit is established shunting the winding of the second track relay AIETRA with the result that the winding of this relay is not energized at this time and its contact 28 remains released.

As the contact 29 of relay AI2H and the contact 30 of relay AI2J are picked up, the circuit of the green or clear lamp G of signal I2S is established, while as contact 32 of relay AIZH is picked up,` the circuit for supplying energy of the code frequency to the track transformer BI ITT is established.

On the supply of energy of 180 code frequency to the track relay BI ITR this relay operates in the same manner as relay BIZTR to repeat the supply of energy of this code frequency to the rails of section AIIT. On the supply of energy of the 180 code frequency to the track relay AI ITR the equipment associated with this relay operates in the manner explained in detail in connection with section AI2T to condition the signal I IS to display its green o-r clear indication, while energy of the 180 code frequency is supplied to the rails of section BIOT.

Operation of equipment on passage of a train through the track stretch When a train moving in the normal direction of traffic Ienters section AIIT, the track relay AI ITR is shunted and ceases to follow code with the result that energy is no longer supplied through the decoding transformer AI IDT to the windings of relays AI IH and AI IJ and the contacts of these relays become released.

As a result of release of contact 29 of relay AI IH, the circuit of the green or clear lamp G of signal IIS is interrupted, while the circuit of the red or stop lamp R is established. On release of the contact 32 of relay AI IH the circuit for supplying energy of the 180 code frequency to the rails of section BIOT is interrupted, while as contact 28 of the second track relay AI ITRA is released, the circuit for supplying energy of the '75 code frequency to the rails of section BIOT is also interrupted with the result that no energy is supplied to the rails of section BIIlT.

On release of Contact 2'I of the relay AI IH the circuit shunting the winding of the second track relay AI ITRA is interrupted, but as the rails of section AI IT are shunted at this time, energy is not supplied to the winding of relay AI ITRA and the contacts of this relay remain released.

`When the train advances far enough in the track stretch to enter section BIIT, the relay BIITR is shunted, and its contact 2!) remains in its released position so that steady uncoded energy is supplied to the rails of section AIIT.

As long as any portion of the train remains in section AIIT, the track relays AIITR and AIITRA are shunted with the result that no energy is supplied to the rails of section BIOT. When the rear of the train Vacates section AIIT, steady energy supplied over contact 2D of track relay BI ITR feeds through the resonant rectifier unit AI IRU to the windings of the track relays AI'ITR. and AIITRA in series, and the contacts of these relays become picked up.

On picking up of contacts 2| and 25 of relay AI ITR an impulse of energy is supplied through the decoding transformer AI IDT to the winding of the relay AI IH, but this relay and the decoding transformer are proportioned so that relay contacts will not become picked up on'the supply of one impulse of energy to the relay winding. yAccordingly, the relay contacts remain released, and contact 2'I continues to interrupt the circuit shunting the winding of the second track vrelay AI I TRA so that the winding of relay AIITRA is energized by current supplied through the resonant rectifier unit AI IRU.

As a result of picking up of contact 28 of relay AIITRA, the circuit for supplying energy vof the 75 code frequency to the rails of section BIDT is established, and the signal next in the rear of signal IIS is conditioned to display its approach or caution indication instead of its stop indication.

When the train advances into section AI2T, the track `relay AI2TR is shunted and the contacts of relays AIZH and AI-ZJ become released, while the contacts of the second track relay AIZIRA remain released, as explained in detail in connection withsection AIIT. vThe signal I2S accordingly is conditioned to display its vstop indication, while the supply of energy to the rails of section BI IT is cut off.

As no energy is supplied to the rails of section BI IT, the contact 20 of track relay BI ITR remains released after the train vacates section BIIT, and the supply of steady energy to the rails of section AI IT is maintained so that the signal IIS continues to display its stop indication, while energy of the '75 code frequency continues tok be supplied to the rails of the adjacent section in the rear.

When the train advances into section'BIZT, the track relay BIZTR is shunted and its contact 20 establishes the circuit to supply steady energy to the rails of section AIZT. When the train vacates section Al2T, the steady energy feeds to the track relays AIZTR and AIZTRA, and on picking up of the contact 28 of relay AIZTRA the circuit for supplying energy ,of the '75 code frequency to' the rails of section BI IT is established. This energyl produces code following operation kof the track relay BI ITB. with the result that the energy supplied to the rails `of section AIIT is changed from steady energy f to energy of 75 code frequency.

On the supplyof coded energy to the rails of section AI IT this energy feeds through the resonant rectifier unit AI I RU andproduces code `following operation of the track relays AIITR and AI ITRA. i

Since steady energy is supplied to the ,track relays AIITR and `AIITRA prior to the time 4that coded energy `is supplied to these relays,

the contacts of the relays are in -their pickedup positions at the time the supplyof coded energy to these `relays is initiated. Accordingly,

on the supply of coded energy tov these relays their contacts remain picked up until the-first off period in the code, whereupon theA contacts of the relays become released. On the first movementof the contacts Aof the relay AIITR to their released positions an impulse of energy is supplied to the winding of relay AIIH from the decoding transformer AI IDT, but, as pointed out above, the contacts ofthe relay AI IH will not become picked up on the supply of a single impulse of energy t0 the relay winding. The

I contacts of relay AIIH, therefore, remain re-v leased on the first movement of the contacts of track relay AIITR to their released position. Another impulse of energy is supplied to the winding of relay AI IH on the first movement of the track relay contacts to their picked-up position, and on the supply of this impulse of energy to the winding of the relay AI IH the relay contacts become picked up.

On the first off interval in the code supplied to the relays AI ITRl and AI ITRA the contact 28 of the relay AIITRA becomes released and interrupts the circuit for supplying energy of the '75 code frequency to the rails of section BIUT.

On the first on period following the first off period in the code supplied to the relays AI ITR and AI ITRA contact 28 of relay AI ITRA may lbecome picked up again, but at this time contact 32 of relay AIIH also becomes picked up and interrupts the circuit for supplying energy of the 75 code frequency to the track transformer BIUTT so that picking up of the contact 28 of relay AI I TRA is without result.

On picking up of the contact 32 of relay AI IH the circuit for supplying energy of the 180 code frequency to the rails of section BIIJT is established, while as a result .of picking up of contact 21 of relay AI IH the circuit shunting the windingof the second track relay AI ITRA is established, and the contact of this relay becomes released if it has become picked up.

In addition, on picking up of the contacts of relay AI IH contact 29 interrupts the circuit of the red or stop lamp R and establishes the circuit of the yellow or caution lamp Y of signal I IS.

From the foregoing it will be seen that when a train enters a block section, the signal for that section is caused to display its red or stop indication, and that when the train vacates the block section, the signal continues to display its red or stop indication until the train vacates the rearward track section of the adjacent block section in advance.

Thus, it will be seen that the signal HS is conditioned to display its stop indication when a train enters section A! IT, and that the signal continues to display its stop indication until'the train has advanced far enough in the track stretch to vacate section AIZT, that is, the rear- Ward track section of the block section next in advance of that with which the signal IIS is associated.

Similarly, when the train advances far enough in the track stretch to clear section AI3T, the equipment associated with section AIZT operates as described above to condition the signal I2S to display its yellow or caution indication, while the energy supplied to the rails of section BIITis changed from75 to 180 code frequency. On this change inthe frequency of the code supplied to the rails of section BI IT the track relay BI ITB. repeats the supply of energy of the higher code frequency to the railsy of section AI IT. On the supply of energy of the 180 code frequency to the relay AIIlTR its contacts operate at the higher speed and sufficient energy is supplied through the resonant rectifier unit AI IRUA to pick up the contact of the relay AMJ, while on i picking up of the .contact 30 the signal IIS is conditioned to display its green or clear indication instead of its yellow or caution indication.

Figs. 2 and 3 of the drawing are diagrams showing the condition of the signals and the types of energy supplied to the track circuits of a track stretch Linder different conditions of track occupancy.

When the track stretch is vacant, coded energy, which may be considered to be energy of a first character, is supplied to the track circuits of the various :track portions in :the :track stretch, .and the'signa'ls for the 'varioushlocksections are conditioned to display theirgreen or clear indications, while-energy of'thischaracter is operative tocondition the cab signal apparatus on a locomotive traversing theztrack stretch to display a proceed indication.

' Asis* shown4 in Fig. 2, when a train is present in the forward track section of a block section, steady energy, which may be considered to be energy of ia second character, is supplied to the rails, ofthe rearward track sectionv of the same block section with, the result that the signal for that. block section is conditioned to display its stopjor mostcrestrictive indicatiomwhile, energy ofi the iirstcharacter,l that is, codedV energy', but ofjthei5 code frequency, is1supplied to the track sections` of the adjacent block section in rthe rear with". the result that the signal for that block section display its yellow or caution indication.

Under the condition of track occupancy illustrated in Fig. 2 a second or followingl train will receive a restrictive indication at the entrance to the block section next in the rear of that in which the first train is located. At this time there are three unoccupied track sections in the rear of the fi-rsttrain, these three track sections being the twosections of the block governed by the signal |25, and the rearward one of the sections of the block governed by the signal |3S. Under these K conditions, therefore, the second or following train has a distance equal to at least one and a half block sections in which to stop after passing a signal displaying a restrictive indication.

Fig. 3 is a diagram showing the condition of the apparatus when a train is present in the rearward track section of a block section. Under this condition the signal at the entrance to the occupied block displays its stop indication and no energy is supplied to the forward track section o-f the adjacent block section in the rear, While steady energy is supplied to the rails of the rearward track section of that block section with theresult that the signal for the block section next in the rear of the occupied block section also displays its stop indication. Energy of the 75 code frequency is supplied to the rails of the track sections of the second block section in the rear ofthe occupied block section, and the signal for that section is conditioned to display its y caution indication, while energy of the 180 code frequency is supplied to the sections in the rear.

It will be. seen that under the condition of track occupancy illustrated in Fig. 3, a second or following train will receive a restrictive proceed indication at the entrance to the second block section in the rear of the occupied block,-

and that at this time there are two full block sections or four track sections in the rear of the rst train which are unoccupied.

Since with the signaling system provided by this invention the braking distance in advance of the signal displaying a restrictive indication is always equal to at least one and a half blocks, theblocks can be somewhat shorter than would otherwise be necessary to provide adequate braking distance with the result that relatively close spacing of trains running under clear conditions is obtained.

In addition, it will be seen that there is always at least one unoccupied track section in advance of av signal Vdisplaying a stop or the most restrictive indication. As shown in Fig; 2, when a train isiin theforward trackzsectionA of a block section,

there is onevacanttrack section in advance of the first-signal .displaying eastop indication, while as vshownin Fig.A 3, whenthe train is in the rearward track section of a-block section, there are two signals in the rear vof `the train which display stop indications, and there are two unoccupied track sections in advance of the vfirst signal displaying a stop indication. This unoccupied space'in advance ofa signal displaying a stop indication provides afactor of safety and prevents collisionsif for any reason a second or following train shouldA run past the stop signal.

The unoccupied track section in advance of the point at which a stop indication is given to a second orfollowing train `is particularly valuable in signaling systems employing cab signals only.

In the usual system having cab signals only the, stop. indication is not received on the locomotive-of a-second or following train until the locomotive is present in an occupied section. In such a system ifthe rst train stops with the rear end thereof adjacent the entrance end of aseotion, a second or following train may not have distance enough in which tofstop afterreceiving the stop` indication.

The cab signal 4apparatus which isadapted to be employed on locomotives operating in track stretches equipped with signaling apparatus embodying this invention is larranged to respond to codedY alternating. current energy, that is, to energyofthe rst character to provide proceed indications, while the apparatus responds; to steady uncoded alternating current, that is, to energy of the second character, or to the absence of energy to providea` stop indication.

Inthe system provided by this invention there is. alwaysY at leastone track section in the rear of a train to which steady uncoded energy is supplied with the result that. the cab signal apparatus on a second or following train will be conditioned toA provide the stop indication at a point atleast one. track section behind the rst train. This gives the engineer of the secondor following train noticethathe is approaching an occupiedv section before the locomotive actually enters the track section in which the first train is located.

It will be seen thatthesystem provided bythis invention employsrenergy of a rst character, that is, energy of the normal code frequencies, in the track circuits to control the Signals, while it employs energy of adifferent or second character, that is, steady energy, in the track circuit vof an overlap portion to extend the control of the sig? nals. While the use of steady energy in the overlap portion has been shown, any distinctive form offenergy may be employed for this purpose.

Similarly, although the invention has been described in connection with a signaling system employing coded and steady alternating current in the track circuits thereof to provide the two characters of energy required in the system, the invention is not limited to the use of this combination of characters of energy. Instead direct current, either steady or coded, may be employed in the track circuits of the various track portions, while the two polarities of direct current may be employed to provide different proceed indications or to distinguish between train detecting energy in an overlap portion and signal control energy. Likewise, it is contemplated that the necessary two characters of energy may be obtained'by employing a combination of alternating and direct current, or by employing energy coded at distinctive frequencies.

track rails over which tralc moves inv a given direction, the rails having insulated joints therein to divide the track stretch into a plurality of successive block sections, the rails of each of the block sections being divided by insulated joints into a forward and a rearward portion, the forward portion of`each block section having an,

electroresponsive device having a winding' receiving energy over the rails of said portion, each such device being operative when and only `when supplied with energy of a first character to effect the supply of energy of said first character to the l rails of the rearward portion of the same block section and operative when not energized to` effect the supply of energy of a second character to the rails of said rearward portion, the rearward portion of each of said block sections having electroresponsive means receiving energy from the rails of said portion, said means being operative when and only when supplied with energy of either the rst or the second character to effect the supply of energy of the iirs't character to the rails of the forward portion of the adjoining block section in the rear and' being operative when not energized to continuously cut the spirit and scope f off the supply of energy to the rails of said for`.

ward portion of the adjoining block section in the rear, and trafc governing means for each of said block sections selectively controlled by the electroresponsive means associated with the rearward portion of said block section in accordance with the character of the energy supplied to the said means.

2. In a railway signaling system, in combination, a stretch of railway track having a pair of track rails over which traffic moves in a given direction, the rails having insulated joints therein to divide the track stretch' into a plurality of successive block sections, the rails of each of the block sections having insulated joints therein to divide the section into a forwardand a rearward portion, the rearward portion of each block section having electroresponsive means having a winding receiving energy over the rails of said portion, each such means being operative when and only when supplied with energy of either a iirst or a second character to supply energy of the rst character to the rails of the forward portion of the adjacent block section in the rear, said means being operative when not energized to continuously cut oi the supply of energy to the rails of such forward portion, the forward portion of each block section having electroresponsive means having a winding receiving energy over the rails of said forward portion, each such means associated with a forwardportion being operative when and only when supplied with energy of the vfirst character to effect the supply of energy of the first character to the rails of the rearward portionA of the same block section and being operative when not energized to effect the supply of energy of the second character to the rails of the rearward portion of the same block section, whereby energy of the e energy supplied to said means.`

5 first characterA is supplied to the rails ofthe rearward portion of each block section when andk only when the forward portion of said block section and the rearward portion of the adjacent block section in advance are. both unoccupied, and whereby at all other times energy of the second character is supplied tothe rails of such rearward portion, and vtraiiic governing means for each of said block sections selectively controlled by the electroresponsive means associated with therearward portion of said block section in accordance with the character of the 3. In a railway signaling system, in combination, a stretch ofrailway track having a pair of track rails over rwhich traflic moves in a given direction, the rails of said stretch having insulatedjoints therein to divide the track stretch into a plurality of successive block sections, the

rails of each of said block sections having insulated joints therein to divide the section into a forward and a rearward portion, the rearward portion of each of said block sections having electroresponsive means having a winding receiving energy over the rails of said portion, said means being operative when deenergized to continuously cut off the supply of energyto therails of the forward portion of the adjoining section in the rear, said means being operative when energized with energy of a rst type to effect the supply of energy of a second type to the rails of the forward portion of the adjoiningv section in the rear and being operative when energized with energy of said second type or of al third type to effect the supply of energy of the third type to the rails ofthe forward portion of the adjoining section in the rear, the forward portion of each block section having electroresponsive means having a winding receivingenergy over the rails of said forward portion, each such means being operative when supplied with energy of the second or third types to effect the supply of energy of the same type to the rails of the rearward portion of the same block section and being operative when not energized to effect the supply of energy of the first type to the rails of the rearward portion of the sameblock section, each of the block sections having at` the entrance end 4thereof a signal governing traffic in said section, thesignal for each section being selectively controlled by the electroresponsive means for the rearward portion of the said section in accordance with the type of current supplied to the said means. y

4. In a signaling system'for a stretch of railwaytrack, in combination, a pair of conductors divided into block sections, the conductors of each block section being divided into a forward portion and a rearward portion, the conductors of each portion being governed by traffic conditions `in such portion, the rearward portion of each of said block sections having electroresponsive the rear and being operative when not energized to lcontinuously cut oi the supply of energy to the vconductors of suchforward portion, the forwardportiongof each block section having electroresponsive means having a windingvreceiving each such means associated with a forward portion being operativewhen and only when supplied vwith energyl of .the first character to effect. the supply of energy of the first character to the conductors forthe rearward portion of the same block section andfbeing operative when not ener gized to effect the supply of energy of thesecond character to Athe conductors of the rearward .portion of the-same block section, whereby the conductors of the rearward portion of each block section are supplied with energy of the first character when and only when the forward portion ofthe same block sectionV and the rearward .portion of the adjacent block section in advance are both unoccupied and whereby at all other times energy of 'the'second character is supplied to the conductors of such rearward portion, and trac governing means for each of said block sections selectively controlled by the electroresponsive means of the rearward-.portion'of such sectionin accordance withthe character of the energy supplied to such means.

5; In a railway signaling system ofthe type lhaving traiic governing means selectively responsive" to different charactersv of energy, in combination, a stretch of railroad'track having a pair of track rails over which traic moves in a given direction, the rails .of the stretch being divided by insulated joints into -a pluralityy of successive block sections, the .rails of eachv of said block sections being' divided by insulated joints intofa forward land a rearward portion, the rearward portion of each'block section having electroresponsive means having a winding receiving energy over the rails of said portion, each such means being operative when and only when supplied with energy 'of either a first or a second character to supply energy of the first character tothe rails of theforward portion of the adjacent block section in the rear, said means being operative when not lenergized to continuously cut off the supply of energy tothe rails of theforward .portion of the adjacent section in the rear, the forward portion of each block section having electroresponsive' means having a winding receiving energy'over the rails of said forward portion, each suchmeans associated with aforward portion being operative when and .only when'supplied with'energy'of the first character to eiTect the supply of energy of thev first character tothe rails of the rearward portion ofthe same block section and being operative whennot energized to effect the supply of energy Yof the second character to the rails of the rearward portion of the same block section, whereby energy of the first character is supplied to the rails of the rearward vportion of each block section when andv only when the forward portion of said block section and the rearward portion of the adjacentv block section in advance are both unoccupied andA whereby at allother times energy of the second character is supplied to the rails of such rearward portion.

6. In a railway signaling system of the type having traffic governing means selectively responsive to different characters of energy supplied to the rails of a track stretch, in combination, a stretch of railway track having a pair of track rails over which traffic normally moves in a given direction, the rails of said'stretch being divided by insulated joints into a plurality of'. successive block sections, the rails of each of the said sections being divided by insulated jointsv into a forward and a rearward portion, the rea-rw-ard portion of eachkblock section having a-n electroresponsive device having'. yawinding redill ceiving energy over 'the rails of saidtportomeach such means being operative when and only when supplied with lcodedor uncoded energy to supply coded energy to therails of the forward portion of 'the adjoining section in the rear, each such means being operative when not energized to continuously cut off the supply of energy tothe rails of such forward portion, the forward portion of each block section having electroresponsive means having a winding receiving energy over the rails of said forward portion, each such means associated with a forward portion being operative when and only when supplied with coded energy to effect the supply of coded energy to the rails of the rearward portion of the same block section and being operative when not supplied with energy to effect the supply of uncoded energy to the rails of the said rearward portion.

'7. In a railway signaling system, in combination, a stretch of railway track having a pair of track rails over which traic moves Ain a given direction, the rails of the stretch being divided by insulated joints into a plurality of successive block sections, the rails of each of said block sections being divided by insulated joints into a forward and a rearward portion, the rearward portion of each block section each hav-ing a rst and a second track relay each having a Winding receiving energy over the rails ofthe said portion, each of said second track relays controlling means operative when and only when uncoded energy is supplied to said relay winding to establish a circuit to supply coded energy to the rails of the forward portion of the adjoiningl block section in the rear, each of said rst track relays controlling means operative when and only when coded energy is supplied Vto the relay winding to render the associated second track relay nonresponsive to coded energyand to establish a circuit to also supply coded energy to the rails of the forward portion ofthe adjoining block section in the rear, the forward portion of each block section having a track relay having a winding receiving energy over the rails ofsuch portion, each such forward portion track relay being operative on. the supply of coded energy thereto to effect the supply of coded energy to theY rails of the rearward portion of the same block section and being operative when not energized to effect the supply of uncoded energy to the rails of the rearward portion of. the same blocksection, and traffic governing means for. each Vblock section selectively controlled by the rst track relay of the .rearward portion of said block section.

V8. In a railway signaling system of the type having trafc governing means selectively responsive to diner-ent characters of energy supplied to the rai-ls o'f`a track stretch, in combination, a stretch of railway ltrack -having a pair of track rails over which traino normally moves in a given direction, the rails of said stretch being divided by insulated joints into a .plurality of successive Vblock sections, the rails of each, of theA block sections being divided by insulated jointsY into a forward and a rearward portion, the rearward portion ofeach block section each having a first and av second track relay each having a winding receiving energy over the rails of thesaid portion,` each of said second track relays controlling means operative when and only when uncoded energyis supplied to said relay winding to establish a circuit to supply wpcoded energy to the rails of the forward portion of the adjoining block section in the rear, each of said first track relays controlling means yoperative when and only when coded energy is supplied to the relay winding to render the associated second track relay non-responsive to coded `energy and to establish acircuit to also supply coded energy `to the rails of the forward portion of the adjoining block section in the rear, the

`forward portionof each block section having a track relay having a winding receiving energy over the rails of such section, each such forward portion track relaybeing operative on the supply of coded energy thereto to effect the supply of coded energy to the rails of the rearward portion of the same block section and being operative when not energized to effect the supply of uncoded energy to the rails of the rearward portion of the same block section.

9. In a railway signaling system, in combination, a stretch of railway track having a pair of track rails over which traffic normally moves in a given direction, the rails of said stretch being divided by insulated joints into a plurality of successive block sections, the rails of each of said block sections being divided by insulated joints into a forward and a rearward portion, the rearward portion of each block section each having a first and a second track relay each having a Winding receiving energy over the rails of said rearward portion, each of said second track relays controlling means operative when and only when uncoded energy is supplied to said relayI Asupply coded energy of a second code frequency to the rails of the forward portion of the adjoining block section in the rear, the forward portion of each block section having a track relay having a winding receiving energy over the rails of such portion, each such forward portion track relay being operative on the supply of coded energy of either code frequency thereto to effect the supply of coded energy of the same code frequency to the rails of the rearward portion of the same block section and being operative when not energized to effect the supply of uncoded energy to the rails of the rearward portion of the same block section, and traffic governing means for each block section selectively controlled by the first track relay of the rearward portion of such block section in accordance with the supply of coded energy to said track relay and also in accordance with the code frequency of such energy.

10. In a railway signaling system of the type having trame governing means selectively responsive to energy of different code frequencies supplied to the rails of a track stretch, in combination, a stretch of railway track having a pair of track rails over which traffic normally moves n in a given direction, the rails of said stretchv being divided by insulated joints into a plurality of successive block sections, the rails of each of said block sections being divided by insulated joints into a forward and a rearward portion, the rearward portion of each block section each having a rst and a second track relay each having a winding receiving energy over the rails of the said portion, each of said second track relays controlling means operative when and only when uncoded energy is supplied to said relay winding to establish a circuit to supply coded energy of a first code frequency to the rails of the forward portion ofthe adjoining block section in the rear, each of said first track relays controlling means operative when and only when coded energy is suppliedy to the relay winding to render the associated second track relay nonresponsive to coded energy and to establish a'circuit to supply coded energy of a second code frequency to the rails of .the forward portion of the adjoining block section in the rear, the forward portion of each block section having a track relay having a windingreceiving energy over the rails of such portion, each forward portion trackrelay being operative on the supply thereto of coded energy of either code frequency to effect the supply of coded energy of the same code frequency to the rails of the rearward portion of the same block section and being operative when not energized to effect the supply of uncoded energy to the rails of the rearward portion of the same block section in the rear.

11. In a railway signaling system of the type having traffic governingy means selectively responsive to energy of different code frequencies supplied to the rails of a track stretch, in combination, a stretch of railway track having a pair of track rails over which traffic normally moves in a given direction, the rails of said track stretch being divided by insulated joints into a plurality of successive block sections, the rails of each 0f said block sections being divided by insulated joints into a forward and a rearward portion, the rearward portion of each block section each having a first and. a second track relay each having a winding, the windings of said track relays being connected in series and receiving energy over the rails of such rearward portion, each rst track relay having associated therewith an auxiliary relay and means responsive to operation of the track relay contacts to supply energy to the auxiliary relay winding, each second track relay being operative when its winding is energized to establish a circuit to supply coded energy of a first code frequency to the rails of the forward portion of the adjoining block section in the rear, each auxiliary relay being operative when its winding is energized to establish a` circuit shunting the winding of the associated second track relay and to also establish acircuit to supply coded energy of a second code frequency to the rails of the forward portion of the adjoining block section in the rear the forward portion of each block section having a track relay having a Winding receiving energy over the rails of such portion, each forward portion track relay being operative on the supply thereto of coded energy to effect the supply of coded energy of the same code frequency to the rails of the rearward portion of the same block section and being operative when not energized to effect the supply of uncoded energy to the rails of the rearward portion of the same block jointsinto enforwardv and a rearward portion, the rearward portion of each block section having`v a firstanda second.A track relay each having a.winding receiving. energy over said rearward portion, each rstLtrack relay having an auxiliary relay associated therewith and having means operative on code" following operationv of the track relay to supply energy to the associated auxiliary relay, each secondv track relay being. operative when uncoded energy is supplied there,- to. to establish a first supply circuit to, supply coded. energy of a first code frequency to the railsY of the forward portion of the adjoining block section in the rear, each auxiliary relay being. operative when energized to interrupt the t energy of the same code frequencyv to the rails of the rearward portion of the same block section and being operative when not energized to effect the supply of uncoded energy to the rails of the rearward portion of the same block section.

HOWARD A. THOMPSON.

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