US1623023A - Absolute-permissive-block train-control system - Google Patents

Description

-1 623,025 March 29, 1927. w w WENHOLZ ABSOLUTE PERMISSIVE BLOCK TRAIN CONTROL SYSTEM Filed March 14, 1925 2 Sheets-Sheet 1 2 Sheets-Sheet 2 MTTORNEY wmxw. w. wENHLz Filed March 14,1925

March 29 1927.

ABSOLUTE PERMISSIVE BLOCK TRAIN CONTROL SYSTEM Patented Mar. 29, 1927.

UNITED STATES,

wanna w. wannonz, or'aocnns'rnn, Haw-roan, Assrenon. 'ro cmnu.

srezmr. comma-or nocnas'rna, NEW You 1 1,623,023 PATENT arms.

RAILWAY ansonurn-rnnnrssm-nnocx mam-coarser. srsrmn Application and 1mm .14, ms. Serial llo. 15,504.

This invention relates to train control systems of the continuous inductive type, and more particularly to trackwa apparatus for such systems for governing t e movement of trains in accordance with the signal restrictions imposed by wayside signals of the absolute permissive t In train control systems of the continuous inductive ty e in which occu ied block protection is a orded by detectlng by suitable car-carried apparatus the flow of current in the usual track circuit ahead of a thin, it is necessary that current be applied across the rails at the exit end of a block or track section for the particular direction in which the train is moving at a particular time; this being true for single track roads where trains run in both directions over the same track as well as in double track systems where trains run in one direction only.

'Ihain control systems of the general type mentioned may be said to be classified into two groups, namely, (1) the two-position type in which the train is governed solely by the presence and absence respectively of current flowing in the usual track circuit flowing down one rail and back through the other, such as shown in the prior application of Wenholz, Serial No. 704,749, filed April 7, 1924; and (2) three-position systems in which the train is verned in-accordance with the presence an phase relation of two different currents flowing res ectively in the usual track circuit ahead of t e train and in a simplex circuit comprising the two rails in multiple, such as is shown in the application of Howe and Bushnell, Serial No. 653,898, filed July 26, 1923. Since the control of the currents applied to the exit end of the block for both of these typesor groups of systems is very much the same, the present applicationwill for convenience be confined to a'system of the two-position t pe.

In railway signaling systems of t e ab solute permissive type as ordinarily installed each block consists of two insulated track sections in which the source of trackway energy is applied at the joining ends of these sections, and one specific feature of the present invention resides in the provision of means for applying track circuit ener for train control purposes to the track ra ls on one side or the other of such intermediate point in a blpck when such train control ourinvention reside in t rent is required of the train without the provision of additional line wires.

Other objects-and urposes of the present In describing the invention in detail referones will be made drawing in which Fig. 1 illustrates many of the essential parts of the trackwa apparatus from one pass ng sidin to anot missive bloc signal system having train control trackway apparatus embodying the prelsent invention superimposed thereon; an

Fig. 2 shows in detail the circuit arrangement and a paratus for one com lete block and the ad acent ends of two other blocks. Referring to the drawin s, an effort has been made to simplify the escription of the present invention by illustrating all of the westbound control apparatus and signals above the track and illustratin the east bound apparatus below the trac that is, illustrating the ap aratus and signals which govern a certaln the right hand side of the track whenv facing in that direction, and also by ap lying reference characters to the various dhvices which speak for themselves.

to the accompanying Generally speaking, the block si a1 sys-- tem as shown s of the type common y known as an absolute permissive block system and is shown and described in detail in the prior patent to Wight, Serial Number 1,294,736, February 18, 1919, so that for the pur se of explaining the present invention on y a brief description of the system itself will be necessary.

,The stretch of track between the two passing sidings PS and PS is divided in the usual way into a number of trackway sections, which have been designated A, B, C, etc. Each of these track sections is provided with the usual track battery shown, and a track relay T having an exponent correspondin to the section-in which the track relay is located. Trains travel over lrection of movement on v of trains in opposite directions into the single track section between the sidings, and are of the type called absolute or starting signals. These absolute signals are made distinguishable from the other intermediate ermissive signals by having square ended blades, as shown, or by the arrangement of marker lights.

Adjacent each of these signals is a home relay. The home relays which govern westbound signals have the referencecharacters HW applied thereto, and the home relays which govern east-bound signals have the reference characters HE applied thereto, and the exponents applied to each of these reference characters correspond to the number of the signal which this relay controls directly. I Each end of each of the track sections illustrated must at some time or other, depending on trafiic conditions and the direction of movement of trafiic, have alternating current impressed across the rails, and for this purpose transformers P have been illustrated. The transformer governing west-bound traflic having exponents aw,

bw", etc applied thereto and the transformer governing east-bound traific have exponents ae, *be, etc-., applied thereto. These exponents correspond to the section in which the transformer is located and the .relay but have a limiting resistance connected in series therewith. This limiting resistance is provided so that the secondary wind-in of the transformer does not efiectively shunt, so to speak, the track relay ofthat section.

Referring particularly to Fig. 1, it should be noted that the home relay HW for the signal Z is controlled by a line circuit (from which certain contacts have been omitted in Fig. 1 but have been shown in Fig. 2) including the front contact 10 of the home relay HW, front contact 11 of the track relay T, front contact 12 of the'track relay three-position home relays may be enermaaoas T so that this home relay 8 is de-ener gized whenever home relay HVV is de-energized, this also being true of the home relays HW and HW with respect to the home relay next to the left. In the same way, the 7 home relay HE is controlled by front contact 14 of track relay T, front contact 15 of track relay T and front contact 16 of home relay HE so that the home relay HE is de-energized whenever the home relay HE is de-energized, the same thing being true of home relays HE" and HF? with respect to corresponding home relays.

From the foregoing it will readily appear that, as far as the i1 ustration in Fig. 1 of the drawings is concerned,a train entering the section of track from the passing siding PS will cause all of the home relays HW, HW" and HW" to assume the de-energized position and will cause only the home relay bIE of the various east-b0 nd home relays HE to be de-energized. It hould be noted at this time, that the circuits for energizing the various home relays begin at either the positive or negative terminal of the battery as indicated. by the reference character B i- (B plus or minus) and terminate at a common return wire G connected to the other side of such battery, so that, these ized to indicate normal and reverse dependmg on .the polarity of the current applied thereto. Each of these home relays directy controls the signaladjacent to which it is located, and causes this signal to assume the clear position when the relay is energized to its normal position, causes the signal to assume the caution position when the relay assumes the dotted reversed position and causes it to assume the danger position when the corresponding-home relay is de-energized. In other words, when an east-bound train enters a section between the passing sidings all of the west-bound signals will assume their danger position, whereasthe east-bound signals will not change from the clear to danger position until the train passes such signal. In'order to permit two trains to pass through the section one behind the other, and be properly protected by signal indications and train control, that is, in order to cause the signal of the first block in the rear of an occupied block to manifest caution conditions and the signals of all blocks in the rear thereof to indicate clear, it is necessary to provide supplemental means for picking up the east-bound home relays in the rear of such east-bound train; and for this purpose the line circuits heretofore traced are modified as more clearlv shown in Fig. 2 of the drawings, this modife cation including 'a stick relay which i picked up as the train approaches the con trol point at which it is located and which relay is' again dropped when the train' has 1 passed entirely out of the block (comprising two track sections) governing this si 7 al as more particularly explained hereinafter. These stick relays have been designated SE and SW, where E and W correspond-to the direction of movement during which such relays are at times energized, and have an exponent applied thereto which corresponds to the signal adjacent to which such stick relay is located.

Referring now more articularl to F g. 2 of the drawings in w ich the b ock comprising track section C and D, and the adacent ends of two other track sections and associated apparatus has been 1llu strated,-1t should be noted that all of the signals are at clear and that each of the track'transformers P shown are not connected to an alternating current source of su ply, this, because one or the other of the pairs of contacts controlling the energizing circuits for these transformers is open i The incomplete line circuit, shown in heavy lines in Fig. 1, for energizing the home rela HW heretofore traced in connection with home relay .HW of Fig. 1 is completely shown in Fig. 2 in heavy lines and includes the following contacts :,-oontact 10 having in multi le therewith a contact 13 operated by t e stickrelay SW back contact 20 of the stick relay SE, and the contactsll and 12 of the-track relays T and T respectivel heretofore mentioned in connection with this circuit. Similar cirilllitS may be traced for the other home re- Operatiom-It is believed sutlicient for a clear understanding of the system to consider the movement of a train through several blocks in one direction only, and note the changes in the relays and signals and when train control current is applied to and removed from the various track transformers, from which it is readily appreciated how other trains equipped for continuous inductive train control are restricted in their movement.

Let us assume that a train is moving from in its retracted position the west-bound home repeater relay or intermediate relay HRW and. the home relay HW for reasons heretofore given, assume their retracted position.

Dropping of the homerelay HW also completes a circuit for energizing the transformer P which circuit includes the front contact 21 of the home relay HW and front contact 22 of the home relay HE in series.

7 Dropping 'of the west-bound repeater relay HRW causes the completion'of a circuit for I energizing the transformer P- which circuit includes a back neutral contact 24: of this relay HRW, a polar contact 25.0f the eastbound repeater polar neutral relay HRE, a neutral contact 26 of the same relay in series. In a similar way energy is applied to the transformer P through aback contact 21' of west-bound home-relay HW and a front contact 22 of the east-bound home relaiy1 HE in series, and so on all the way throug I assing the single track section to the next siding. .So that, each of the trans v ormers illustrated in Fig. 2 which govern the movement of traflic from left to right is energized.

If now the train in question, moving from left to right, enters the track section C, the

.track relay T assumes its de-ener zed posirelay SE once ener ized a stick circuit is completed which inc udes the back contact 31 of the home relay HE and the front contact 32 of the stick relay SE, so that, this relay is stuck up so long as the home relay HE is in its retracted position.

Each of the signals also includes a pole changer switch PC which assumes the normal position illustrated during the clear and caution position of the signal, but assumes the dotted position when the corres nding signal is in the danger osition, so t at, the pole changer switch P8 now assumes the dotted position since the signal Z assumes the danger position. With this pole chan r switch PC reversed and the stick relay E energized, negative energy is applied to the line wire (see Fig. 1) controlling the next home relay HE in the rear (and also the repeater relay connected to this line wire, not shown) through contact 17 of the stick relay SE, so that these relays are energized to the reverse position! With the home relay HE energized to the reverse position the signal Z assumes the caution position. As the rear end of the train leaves the section B the track relay T" again assumes its energized position thereby re-energizing the line relay HW. Since the home relay HE is still -de-energized current is incidentally applied to the track transformer P" as is obvious from Fi .2 of the drawing. This application, 0 current permitting west-bound movement while a train is moving eastward is harmless, because it 00-- curs only when the track section to which it tained is already open. Dropping of contact 15 de-energizes the home repeater relay HRE connected to the other line wire, so that alternating current sourceof supply is cut off of thetransformer P" so that the 4 track section C isno longer provided with alternating current andtherefore does not permit unrestricted east-bound movement of a train in the rear of the train in questlon, and dropping of contact 35 of thetrack relay T" closes abreak in the pickup circuit for the stick relay SW but this clrcult can not be completed because the signal Z has long previously assumed its danger position, so that the net result of passing into section is the de-energization of the transformer P".

Let ius now assume that the train continues its movement in the east-bound direction and enters the tracksectlon E (see F 1g. 2) as it'enters this track section the stack relay SE is picked up and stuck up in a manner as heretofore described in connec-- tion with stick relay SE, and the movement of the signal Z to the danger position causes reversal of the pole changer switch PG. As soon as the rear end of the train leaves the section D, in addition to the fact that home relay HW picks up if there is no other train following the train in question as heretofore vmentioned, the

track relay T again icks up; whereby negativeenergy is app ied to the line circuit including front contact 17 of the stick relay SE, back contact 37 of the stick relay. SW front contact 15 of the track relay T, front contact 14iof the track relay T and the home relay HE in series, so that this home relay HE is energized to. its reversed dotted position and causes the signal Z to assume the caution position.

As soon as this occurs, on the assumption that there is another train in the single track section following the train in question, the transformer P is again. energized, so that, a following train may-detect alternating current in the track rails ahead of it and pro-v oeed unrestricted up to the transformer P By reason of energization of the line wire just mentioned the east-bound home repeateflrelay HRE is also energized, but in this case it is energized by current of reversed polarity, so that, the polarized concontact 15 of the track relay T acaaoas and does not yet re-apply current to the transformer P. i

As the train proceeds through the track section E and finally moves entirely out of this section, the track relay T again picks up, but .this does not effect energization of the home relay HE because the line circuit for this home relay is open at the front 51sec Fig. 1), but when this train has passe out of the section F ;the-.track relay T picks up and completes an energizing circuit for the hpme relay HE, but the current applied to this relay HE is of negative, polarity-for reasons heretofore given, so that, the signal Z assumes only its caution position, Y but this change in the signal Z causes the pole changer switch PC to again !assume its normal position. With this pole changer switch returned to normal by snap action, current of' a positive polarity is re-applied to the line wire fed from this pole changer switch. and in turn the repeater home relay HRE is energized to the normal posi tion; so that if another train is following the train in question and by so doing, deenergizes the repeater relay HRW, current is re-applied to the transformer P so as to permit unrestricted movement of such following train up to this transformer P at least. Also, the picking up of home relay HE to the reverse position, effects closing of contact 22' and re-energization of the transformer P, so that, proceeding on the assumption that a train is approaching from the rear, this train may detect current in the track rails and proceed unrestricted up the signal Z. Also, upon further progress of the train, positive energy is reapplied to the home relay HE which causes the signal Z to assume the normal clear position.

From the foregoing description of the invention it readily appears that the entrance of a train into a single track section causes the application of alternating current to all of the transformers connected to the exit end of the various sections for the particular direction of movement in question. In this case it should be noted that the entrance of a train into the first section is accompanied by the dropping of the track relay T or T, as the case may be, and effects the application of such alternating current to the transformer of the corresponding section. Tn practice, the time necessary to apply the alternating current to the transformer after this relay changes is less than that necessary to effect a speed restriction upon the train. In other words, the train carried mechanism intended to be employed in connection with the trackway apparatus embodying the present invention, is such, thata train may travel for a predetermined period of time or a predetermined distance without being restricted even though no alternating current can be detected in the track rails at the time. Also, as a train passes through the single track section no trackway current can 6 be detected by a train immedlatel in the an of the train in. question in t e same rack circuit, nor can such train detect current in the track circuit of the next block in the rear of a block occupied by a train, so y in that, the net result is restriction of movement of trains in the rear of the first train.

for at least one blockj(two sections) in addition to the block occupied by such train and absolute restriction of movement trains in the opposite direction to that of the train in question in all the blocks ahead of the train in a sin le track section.

By looking at ig. 2 of the drawings it will be observed that only two line WINS extend from the signals A and Z to the signals Z and Z, and, as is understood by those skilled in the art of the single trac signaling, these two line wires are employed in the usual absolute permissive block signaling systems, so that, no additional line wires are necessary in accordance with the present invention for ap lying trackway apparatus for train contro of the continuous inductive t pe, to an absolute permissive block sign'a 'ng system of a well known and commercial type such as described in the patent hereto ore mentioned. Also, in accordance with the present invention a great saving of energy is effected because no alternating current is necessary on any of the track transformers P shown except when a train is moving in a section between two assing sidings, and then, only the, trans ormers for the direction of movement in which that particular train is moving are energized.

Havin thus shown and described, rather specifica y, one particular arrangement whereby train control of the continuous in, ductive type may be applied to single track signaling s stems of the absolute rmissive type, it IS esired to be underst that this preferabl SPBClfiOdlSClOSIIIB hasbeen made to convey the 0 rating features of a system embodying t e present invention rather than illustrating the particular circuit arrangement employed in practice and that various 0 anges, modification and additions may be made to adapt the invention to other types of single track signaling or train control systems. For instance, the. same general method of energy saving accomplished by the approach control may be applied to slightly modified absolute-permissive-block signaling systems-employing continuous inductive type train control; also a train control system requiring the presence of both simplex and track phase current in the trackway, commonly known asthreeosi tion system may be applied to the. single train any distance in a stretch traveling in the o posite direction,

track signaling system shown, without departing from the scope of the invention or the idea of means underl the same.

What it is desired to be secured by Letters when there is a train moving over such stretch in a certain direction except the section in the rear of such train of the block occupied by a train and thersections of the block in the rear of such train.

2. In combination, a stretch of railway track divided into blocks, each block comprising twosections divided byan insulated oint, a track relay and a source of direct current connected in series with each sec-' tion arranged so that the direct current sources are located at intermediate points inthe blocks, transformers having the sec-' ondary connected in series with said direct current'sources of energy and in multiple with said track relays, hne circuits connect ing the ends of the blocks, an alternating current transmission line relays located at the junctions of the sections of each block I and controlled in accordance with traflic conditions as manifested by track relays in advance thereof through the medium of said line circuits, said relays having conthe transmission lines tacts for connectm to the transformers ocated at theexit end of a section when a train moves in such stretch of track in a particular direction.

3. In combination, a stretch of railway track divided into control zones, a polar relay at the entrance end to each zone for both directions oftravel which assumes a 'y' manifesting dangerous trailic conditions when there is a tram in that zone or the next zone in advance traveling in the or there is a' ance' 1n such tion governed by that relay, v

a line wire for each of sai relays extending along the zone for governing such rela' accordance with 'traflic conditions a ead, means including said line wire for appl ing alternatingv current to the exit end of the first section of such zone when there is a train moving in that direction in said.

sitior n accordance with trafiic conditions i stretch of track but is not yet occupying the 7 second sectionof the zone in question..

4. Trackway apparatus for automatic train control systems f the continuous inductive t pe comprising incombination, a stretch 0 trackway divided into blocks each constituting two sections divided by an 1nsulating joint; a polar relay at the entrance and to each block for each direction of travel manifesting dan er when the block at the entrance to whic it is located is occupied b a train moving in that direction or any block in the stretch of track in advance thereof is occupied by a train moving in the opposite direction, said relay indicating caution if the next block in advance is occuied by a train moving in the first mentioned direction and indicating clear if all the blocks in advance of such stretch of trackway are clear; a transformer at the exitend of each section for governing the movement of trains for a particular direction of travel; a line wire for each relay extendm along the block at the entrance to whidh such relay is located; means for applying alternating current to the transformer at the exit end of the block when the polar relay at the entrance to the block next in advance indicates clear, and an intermediate relay for each line wire located at an mtermedrate point in the block for applying alternating current to the transformer at the exit end of the first section of a block when the polar relay at the entrance end to the next block' in advance is indicating clear and thesection in advance of such intermediate relay is unoccupied.

5. Trackway apparatus for automatic train control systems of the continuous 1nductive type comprising in combination, a stretch of track divided into blocks each constituting two sections divided by an msulated joint; a polar relay at the entrance end to each block for each direction of travel manifesting danger when the block at the entrance (to which it is located is occupied by a train moving in that direction or any block in the stretch of track in advance thereof is occupied by a train moving in the opposite direction, said relay indicating caution if the next block in advance is occupied by a train moving in the first mentioned direction and indicating clear if all the blocks in advance of such stretch of trackway are clear; a transformer at the exit end of each section for governing the movement of trains for aparticular direction of travel; a line wire for each relay extending along the block at the entrance to which such relayis located; means governed by the relay at the entrance to one block for under clear traflic conditions of such block applying alternating current to the transformer at the exit end of the block in the rear thereof, and

a supplemental relay at the exit end of the first section of the block in the rear of said one block cdnnected directly to one of the' line wires and for applying alternating current to the transformer at the exit end of said first section when said 'one block is unoccupled. I Trackway apparatus for' automatic train control systems of the continuous 'inductive type 'fcomprising in combination, a stretch of trackway dlvided into blocks each COIlStllZlltlIlg two sections divided by an"insu,-,

lating joint; a polar relay at the entrance 1,

end to each block for each direction of travel governed bytrack relays of the two sections of such block'for manifesting danger when the block at the entrance to which a particular relay is located is occupied by a train moving in that direction or any block in the stretch of track in advance thereof is occupied by a train moving in the opposite direction, said polar relay indicating caution if the next block in advance of such block is occupied by a train moving in the fir;t mentioned direction and indicating clear if all the blocks in advance in such stretch of rent to the transformer at the exit end of the block in the rear thereof, a supplemental rela at the exit end of the first section of the lock in the rear of said one block connected directly to one of the line wires and for applying alternating current to the transformer at the exit end of said first section when both said one block and the second section of the block in the rear thereof are unoccupied.

7. In an automatic train control system of the continuous inductive type, the combination with a track divided into blocks by insulating" joints of which each block is divided into two sections by insulating joints, a transformer for each section having its secondary winding connected across the rails at the exit end of such section, a track relay for each section, a line relay at the entrance end of each block, an ener 'zing circuit for said line relay including a ine wire extending throughout the length of such block and including a contact closed if the next block in advance is unoccupied and also including contacts of the track relays of the first and second section for normal direction of traffic, an intermediate relay located at the junction of two sections of a block connected in multiples with said line relay in a manner to be governed by the track relay of the second section of said block for the normal direc- "tion trafidc but not to be governed by the track' relay of the first section, means forapplying alternatingcurient to the transformer of the last section of. asblock' when the line relay at the entrance to thenext' block 'in advance is energized, and means for applying alternating current to the transformer of the first section when the intermediate relay at the exit-end of such first section is energized.

8. Intrackway apparatus for automatic train control s stem of the continuous. in-

"section, an intermediate relay located at a 'unction of two sections of a block connected in multipleiwith said line relay ina manner to be governed by the track relays of thesec tions of said block inadvance of such junction for the normal direction of traffic but not governed by the'track relays of the sec-- tions in the rear-of such junction, means for applying alternating current to the transformer of the last section, of a block when the line relay at the entrance end to the next block in advance is energized, and means for applying alternating current to. the transformer of the section of the block in the. rear of such junction when the intermediate relay at such junction is energized. v 9. Trackway apparatus for automatic train control systems of the. continuous inductive type comprising in combination, a stretch of track' divided. into blocks each constituting two sections divided by an insulatedjoint' I polar relax at the entrance endto' each block for each irection of travel manifesting danger whengthe block at the entrance to which it is located is occupledoly a train moving in that direction or anybl in the stretch of track in advance thereof is occupied by a train moving in the op osite direction, said relay indicating cautionif the a next block in advance is occupied by a train direction 5 a transformer at the exit end of each section for governin the movement of trains for a particular lrection of travel; a line wire for each polar relay extending along the block at'tbe entrance to which insulating joints of ductivet said polar relay is located; means governed by the-polar relay at the entrance to one bloc for under clear tr aflic conditions of such block applying alternating current to the transformer at the exit end of the second section'of the block in'the rear thereof. and a supplemental relay at the exit end of the first section of the-block in the rear of said one block connected directly to one of the line wires and controlled to apply alternatcurrent to the transformer at-the exit on .of said first section when'said one block and said second section are unoccupied.

10. Trackway apparatus for automatic tr in control systems of the continuous inconstituting two sections divided by an insulat end 0 pe comprising in combination, a stretch o trackway divided into blocks each joint; a polar relay at the entrance a each block for each direction of, 86

travel governed by-track relays of the two 1 ,sections of such block for manifesting danger when the block at the entrance to which a particular relay is located is occupied by a train moving in that direction or any block stretch of track in advance thereof is occupied by a train movin in the op 0 site direction, said 'olar re ay indicating caution if the next b ock in advance of such block is occupied b strain movin in the first mentioned direction. and in icatin clear if that block and the next block in a vance in such stretch'of trackway are clear and there'is no train in advance moving in o posite direction; a transformer at the exitjend of each section for governin ar relay in advance an the tra relays of the sectionagof the block in question; means governed by the polar.relay at the entrance to one block for under clear .traflic conditions of such block applying alternating current to the transformer at the exit'end of the block in the rear thereof, and a supplemenat the exit end of the first section tal of the" lock' in the rear of said oneblock connected directly to one of the line wires and governed to apply alternatin current to the transformer at the exit en of said first section, when both said one block and I 1 the second sectionof the block in the rear thereof are unoccupied. Y

11. Trackway apparatus, for automatic train control systems'of the continuous inductive type for single track railroads o1 latin vjoints; a track circuit for each section ncluding 'asource" of current and a ided into the movement of a-train for a correspon direction of travel; a line wire for each p0 extending along the block at the entrance to which such relay is located controlledby the polar role of the block next track relay; a transformer at'the'exit end of each section having its secondary wind "ing connected in series with such source of block; a home relay at the entrance end to each block; a circuit for each intermediate relay including a source of energy, a front contact of the home relay at the entrance to the block in advance and a front contact of the track relay of the section immediately ahead of said intermediate relay; a circuit for each home relay energized by the potential drop across the intermediate relay in advance and including a front contact of tlie track relay of the section between such home relay and such intermediate relay; a circuit for energizing the transformer at the exit end of the second section of a block including a front contact of the home relay at the entrance to the block next in advance; and a circuit for energizing the transformer at the exit end of the first section of a block including a front contact of the intermedi-- ate relay 12. Trackway apparatus for automatic train control systems of the continuous in ductive type for single track railroads of the absolute-permissive-block type comprising; a stretch of single track divided into lay; a transformer for each end of each section having its secondary winding connected in series with such source of current or in multiple with such track rela as the case may be; an intermediate relay ocated at the junction of two sections of a block for each direction of movement; a home rela at the entrance end to each block for each irection of movement; a circuit for each intermediate relay includin a source of energy, a front contact of the ome relay at the entrance to the block in advance and a front contact .of the track relay of the section immediately ahead of said intermediate relay; a circuit for each home. relay energized b the potential drop across the intermediate relay in advance and including a front contact of the track relay of the section between such home relay and such intermediate relay; a circuit for energizing the transformer at the exit end of the second section of a block including a front contact of the home relay at the entrance to the next block in advance, and a back contact of the home relay at the exit end of the block in question; and a circuit for energizing the transformer at the exit end of a first section of a block including a front contact of the intermediate relay of such block governin traffic in the corres onding direction and t e back contact of t e intermediate relay of such block governing traffic in an opposite direct1on.-

In testimony whereof I aflix my si ature.

I WALTER W. WE O

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