US543591A

US543591A - Railway signaling system

Info

Publication number: US543591A
Authority: US
Publication date: 1895-07-30
Anticipated expiration: 1912-07-30

Description

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T. B. DIXON. RAILWAY SIGNALING SYSTEM. No. 543,591. Patented July 30, 1895.

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RAILWAY SIGNALING SYSTEM.

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RAILWAY slGNALING SYSTEM.

Nb. 543,591. Patented July 30,1895.

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- RAILWAY SIGNALINK} SYSTEM.

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RAILWAY SIGNALING SYSTEM.

No. 545,591. PatentdJIiIy so, 1895.

WITNESSES.

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T. B. DIXON.

RAILWAY SIGNALING SYSTEM.

No. 543,591. Patented July 30, 1895.

WITNESSES. AWN

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T. B. DIXON. J A RAILWAY SIGNALING SYSTEM. No. 543,591. Patented July 30, 1895.

PATENT Fries."-v

THOMAS BULLITTDIXON, OF HENDERSON, KENTUGKY.

RAILWAY SIGNALING SYSTEM.

SPECIFICATION forming part of Letters Patent No. 543,591, dated July 30, 1895. Application filed November 1'7, 1 892. Serial No,452,358. (No model.)

To all whom it may concern:

Be it known that I, THOMAS BULLITT DIXON, a citizen of the United States, residing at Henderson, in the county of Henderson and State of Kentucky, haveinvented certain new and useful Improvements in Railway Signaling Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates, generally, to automatic railway signal systems, and particularly to improvements in automatic electrically-operated block-signal systems; and it consists in the novel disposition and arrangement of the signals and in the novel and improved arrangement of the circuits for accomphshing the results hereinafter specified. In asystem of automatic block-signals it is desirable that the arrangement of signals besuch that no possible train-movement can be made in which the train-making it will not be fully protected by signals, and also that in certain situations the direction in which a train enters a block shall be indicated by the signals. It is also desirable to have the signals automatically controlled-in such a mannor that station operators will have the power, Without interfering with the operation of the automatic signal controlling apparatus, to set any of the signals to danger, so as to block any desired section of road against trains which may be approaching or leaving their stations, and thereby retain such trains at any desired point, the automatic feature of the system remaining undisturbed, however, so that, while an operator may have the power to set a signal or series of signals to danger at any time, he can have no power to set them to safety when atrain is under their protection. It is further desirable that an automatic block system shall be continuous, not only where the line of road is unbroken by branch tracks, but where itis broken by branch tracks of any kind whatsoever, and that its operation shall be such that when a train passes from a main track to a branch track or from one main track to another by a crossover the maintrack signals will indicate danger until the train shall have passed completely from the main track and beyond their protection,

and also that when a trainshall be on a branch track it must be held there by the main-track block-signals being at danger should it happen that another train is within the block that the train standing on the branch track must enter when it shall pass onto the main track. It is still further desirable that when a train shall pass from one track to another, as from any branch track onto the main track or from one main track to another by a crossover-track, it shall set the main-track signals, under whose protection it is to proceed, to danger before it shall pass onto the main track, thereby making it impossible for a train ever to be on any portion of track unprotected by signals.

In an automatic block system it is further desirable that all of the apparatus which serves to-automatically control the signals shall be automatically returned to its normal position after the train operating it shall have passed out of the block governed by it, whether that train shall have passed out of the block at the same end at which it entered 'trical connections so that any accident to the circuits by which they are rendered inoperative shall of itself cause the signals to go to danger, if at safety, or shall make it impossible to restore the signals to safety, if at danger, until the circuits shall have been placed in working order; third, to prevent false indications due to crossing of the wires; fourth, to render the system economical in the use of battery power and in the number of wires required to operate it; fifth, to render it impossible for a signal to be returned to safety until the train which first set it to danger shall have passed completely beyond its protection; sixth, to prevent confusion and misunderstanding owing to trains which are moving in opposite directions entering the same block from opposite ends at the same instant; seventh, to so arrange all the signalcircuits that any signal or series of signals may be operated by the station operator or other qualified person for the purpose of stopping or holding trains, but so that the automatic operation of the signals can in no way be interfered with thereby, thus making it impossible for any mistake of the operator to lead to the display of a false signal. These objects are attained in the system of signals herein described,and illustrated in the drawings which accompany and form a part of this application, in which the same reference letters and numerals indicate the same or corresponding parts, and in which- Figure 1 shows my system of signals applied to a short section of a single-track railway and provides for travel in both directions over this track. It also shows an application of the system to a single-point siding. Figs. 2 and 3, which are to be regarded as one continuous drawing, the track and wires at the top of Fig. 2 and the bottom of Fig. 3 matching, show my system of signals applied to a double-point siding which has a great amount of traffie passing over it, the situation being that common at stations. Fig. at shows my system of signals applied to a section of a double-track railway, travel ordinarily being in only one direction on each track. Figs. 5 and 6 show the arrangement of signals and circuits for double-track crossovers, Fig. 5 being the arrangement best adapted to crossover-tracks which are of sufficient length to permit of placing the trackinstrument wholly between the two parallel tracks, while Fig. 6 is the arrangement best adapted to situations where the tracks are too close together to permit of placing a trackinstrument on the crossover-track. Fig. 7'is an enlarged view of the centralportion of Fig. 6. Fig. 8 shows a modified method of operating the front relays and signals. Fig.9 shows an arrangement for controlling the front relays and signals by means of circuits analogous to those employed in the differential systems of duplex telegraphy, two line conductors being by this means dispensed with. Fig. 10 shows a modified arrangement for con-. trolling special siding-signals. Fig. 11 is a diagram of a track with two sidings branching from it very near together and facing in the same direction. Fig. 12 shows a siding provided with a crossover to the main track, the crossovertrack being too short to permit of placing a track-instrument upon it. Fig. 13 shows a side track which is of such length that it is desirable to have it provided with a signal system of its own separate from the main track. Fig. 14. shows a modified method of operating the dotted'line or clearing circuits.

In the drawings I have indicated by different kinds of lines the diiferent classes of circuits used in my system. The full lines represent local circuits, which lie entirely within the signal-stations to which they belong and which directly control the home and distant signals. The dashed lines repre sent line-circuits, which extend from signalstation to signal-station and the function of which is to control the special front signals, to be hereinafter mentioned, and to set signals in front of a train to protect it in front. In other words, their function is to control the front signals. The dotted lines likewise represent line-circuits extending from signalstation to signaLstation, their object being to clear signals in rear of a train when the train has passed under the protection of other signals in advance.

I have designed this system of signals to be operated by a circuit-breaker or track-instrument of my invention, which forms the subject-matter of an application for Letters Patent filed November 17, 1892, Serial No. 452,356. I do not confine myself, however, to the use of any particular track-instrument, my system being adapted to be operated by any track-instrument which will operate signals differently, according to the direction in which a train passes over the track-instrument, which is capable of operating, simultaneously, two or more circuits, either normally open or normally closed, or both, and which is adapted to close a normally-open circuit for an instant only immediately after the passage of the train. The location of this trackinstrument at each signal-station Ihave indi cated by two short parallel lines placed just outside the rails, which represent the rail-levers by which the track-instrument is operated. Near these two parallellineslhavediagrammatically represented the various con tact-points of the track-instrument in positions best adapted to permit of diagrammatic illustration of their action, without regard to their actual positionsin the mechanism of the track-instrument and without attempting to show the means by which they are operated; but in order to operate my system it is not essential that the contact-points herein shown as being a part of the track-instrument shall be mechanically a part of the track-instrument, since they might be located at a distance from the track-instrument and operated indirectly by it in any suitable manner. For instance, they might be operated by an electromagnet the circuit of which is controlled by the track-instrument, or by fluidpressure devices, or by compressed air, any means of this sort being substantially, though not actually, a part of the track-instrument; and what has just been said in relation to the track-instrument contact-points applies with equal force to the switch-instrument contact-points, to be hereinafter mentioned.

The signals which I propose to use in this system and which are indicated in the diagrams by electromagnets placed by the' side of the track, with their poles facing in the directions in which the signals which they represent should face, are of my invention and form the subject-matter of an application for Letters Patent filed July 28, 1892, Serial ICC No. 441,480. In these signals the'signalarm or blade is arranged to'be moved into the danger position by a weight when the circuit around'a controlling-magnet is broken, the signal arm being returned to position by suitable means when the controlling-magnet is again energized by the completion of the circuit around it. It is this controlling-magnet which in the diagrams is used as a representation of the signal itself, and in the description of the operation of the system it is to be understood that when the circuit of a signal-magnet is broken that signal is placed at danger and that when the circuit is closed the signal is restored to safety.

It is obvious that it is not essential to the operation of my system that this particular signal be used or that a signal which when at safety is in a closed circuit be used, since, as will be seen hereinafter, the compound relay or governor, as I prefer to call it, which directly controls the circuits is as easily adapted to close as to break a circuit by the fall or rise of its armature, since all electrical signals are controlled by a breaking or completion of a circuit around the electromagnet.

In the diagrams I have shown the Various circuits controlled by a relay or governor having, except in certain situations to be hereinafter mentioned, a number of sets of contact-points adapted to be operated by the movements of'the armature of the said relay or governor, the different sets of contact points being insulated and adapted each to control a different circuit. This governor is of my invention and forms the subject-matter of. an application for Letters Patent filed November 17, 1892, Serial No. 452,357, where it is more fully described. As stated in the specification of this relay, certain of the contact-points are continuity-preserving contact-points, so that separate adjustment of the various sets of contact-points is possible and so that it is possible to cause an armature contact-point when thearmature falls or rises to make contact with one contact-point before breaking contact with the other contact-point. I do-not confine myself to the use of this particular relay or governor, since the system will Work equally well with other instruments fulfilling the condition of having the contact-points adjustable and capable of preserving the continuity in the manner above stated; orI may use a number of sepai rate relays placed in the same circuit, some continuity preserving contact-points, in this case the construction of the front relays being'the same as of the governors. The front relays of Fig. 9 differ from those of the other figures in being polarized relays; The function and operation of all of these relays will be apparent hereinafter.

My signal system is of the class known as block-signal systems, in which the road is divided into a number of sections known asblocks, within which, under ordinary circumstances, only one train is allowed at a time. If the road be a single-track, requiring provisio n'for trains running in'both directions over it, there are signals at each end of every block, facing so as to be seen by the engineer of a train approaching that. block. If the road be a double-track road, travel being ordinarily in one direction only over each track, there is needfor signals only at the end of each block which a train will first approach on enteringthat block, On single-track roads a train must be protected in front from trains going in the opposite direction and in rear from trains going in the same direction, while on double-track roads only the latter protec-,

tion is required.

On asingle-track road or on any section of road where traffic is in both directions over it blocks in front of a train are termed front blocks and blocks in rear of a train are termed rear blocks, because of the manner in which the signals of those blocks are operated. On double-track roads there are no front signals, except at crossovers, and hence no frontblocks.

Fig. 1 shows diagrammatically a section of a single-track railway comprising three signal-stations A, B, and O, the track between Aand B and B and O constituting in each case a block. In this figure, A is shown as the beginning of the line, and traffic of the kind and character to require protection and control by block-signals is not supposed to extend beyond it, the signal-circuits being modified accordingly. The track is supposed to extend indefinitely beyond station 0, being divided into blocks in the same manner that the section of track from A to C is divided.

At O is shown a single-point siding with suitable signal connections therefor, as will be hereinafter described.

Sidings, such as shown at C, will be located at intervals along the track to permit of trains passing. They will usually be located at the point of division between two blocks, though not necessarily at every point of division between two blocks. The signals of the system must be sooperated, however, that when a train enters the section of track intermediate meeting another train at a point where they Thus in Fig, 1 the signals of cannot pass.

the section of track between signal-stations A and O are so operated that a'train entering the block A B at A sets signals at A to protect itself in rear from trains following, and it likewise sets signals in front, not only at 13, but also at C, to protect itself from trains moving in the opposite direction. A train entering the block B G at 0 sets signals at stations 0,15, and A in a similar manner. A train entering at either end of the section of track A 0 therefore closes that section of track to trains going in the opposite direction until it shall have passed out of the said section again.

If the onlysignal-stations within the section of track between two sidin gs or passing-points be at the ends of the section, then a train entering at one end of this section must not only close this section to trains going in the other direction, but also closethe section to trains going in the sanie direction and retain the section so closed until the train shall have passed out of the section again. It is not convenient o1 economical, however, under ordinary circumstances, to have sidin gs on the main track at distances less than several miles apart, while it suitable signal arrangements be provided trains may, and it is desirable that they should, be permitted to follow each other at much shorter distances than the usual distance between sidings on the main line.

On most roads it is necessary, in order to increase to a maximum the amount of traffic possible, with due regard to safety, and to accommodate peculiar conditions of traflic, to permit trains going in the same direction, as, for instance, two sections of the same train, to follow each other at a much shorter distance than the practicable length of that section of track which must be closed to trains going in the other direction. For this reason the section of track between two sidin gs and passingpoints should usually be divided into two or more blocks, except where sidin gs are quite close together, each block having at its entrance signals which are set to danger as the train passes them, while the signals at the entrance of the rear block next behind are returned to safety as soon as the train has passed completely out of that block, thus perniittin g a second train to follow the first at the distance of a block. This feature is illustrated in Fig. 1 and the subsequent figures.

In Fig.1 the section of track from A to C is divided,as previously stated, into two blocks viz., theblock from A to B and the block from B to C. Aswill be hereinafter described, when a train has passed from block A B to block B C the rear signals at B for the direction from A to O are set to danger, while the rear signals at A, previously at danger, are returned to safety, thus permitting a train to enter the block A B at A while the first train is in the block B C, but, as willbe hereinafter explained, maintaining closed the front block B U at O to all trains from C until all trains from A have left the section of track A C; but in order to permit reverse movements of trains at any point within the section of track between A and C it is essential that the front signals at B set bya train at A for the direction from A to 0 shall be restored to safety after the train shall have passed entirelyinto the block B G, and, consequently, beyond their protection, and the same is true for all other block-sections comprising a part of my system for a single track or for any track on which trains ordinarily move in both directions. Therefore when a train shall have passed from block A B into block B C the block A B will be clear for the train to again enter it in the direction from B to A-i. a, in the direction opposite to the original direction-provided no second train shall have ontered the block A B at A. In case a second train shall have entered at Athe frontsignals atB willindicate danger, having been setor maintained at danger by the second train which entered at A.

The section of track fromA to C and the other similar sections of track may be termed signal-divisions. A signal division-may be defined as a section of track which, when a train enters it at one end, is closed by signals to trains going in the,direction oppositeto that of the train first named until the first train shall have passed completely out of said division. Such a signal-division may include only one block or it may include a. number of blocks, according to the arrangement of the signal-circuits. It will usually have at each end a siding.

In the drawings, contact-points, governors, relays, and signals for the direction from A to C are on the right side of the track and for the direction from C to A are on the left side of the track.

Taking up the diagrams in detail and beginning at signal-station Ain Fig. 1, and y are the track-rails; a, the track-instrument at station A. a isthe home-signal at the entrance of the block, and a is a special front signal in a circuit separate from that of signal a the function of which circuit will be hereinafter described. a is the governor, previouslymentioned, which controls the various circuits and from which they radiate. ca are normally-closed circuit contact-points of the track-instrument a for direction from A to C. 1 is a closed-circuit battery, the circuit of which runs from the positive pole of the battery through the contact-points ca of track'instrument a to 2, where it branches, one branch going to the third contact-point of the governor a, thence through the coils of the governor-magnet if the armature of the governor be up to 3, and thence back to the negative pole of the battery. The other branch from 2 goes to the coils of signal-magnet a thence through the contact-points of relay to" and through the second contact of governor a to 3, and so back to battery.

'VVhen a train passes over track-instrument a in the direction from A to O the contactpoints co, are separated, breaking the fullline circuit, and thereby causing the armagether.

ture of governor a to drop, at the same time, as previously explained, setting signal a to danger. It will be noted, however, that at station A both branches of the full-line circuit pass through the contact-points of the governor, the one through the third contact of the governor and the other through .the second contaot,so that the full-line circuit remains open when, after the passage of the train, the contact-points ca are brought to- The full-line circuit can then .be again completed only by the raising of the armature of governor a, which is the function of the dotted-line circuits, but which is not done until either afterthe train has passed station E or has reversed its direction and passed over track-instrument a in the direction from C to A. It will be noticed that at station E and the other signal-stations where there are signals for both directions the branch of the full-line circuit which passes through the coils of the governor-magnet is broken in two places bythe fall of the governor-armature-viz., at the second and fourth governor-contacts. This is necessary to prer vent the completion of a false connection through the contact points of the governor on the opposite side of the track, which, if completed, would render the circuits inoperative.

Omitting for the present description of both dotted-line and dashed-line circuits at station A, and proceeding to station E, b is the track-instrument.- b and b are respectively distant and home signals for station B, and b the specialjfront signal. Signals b and b are in the same full-line circuit, and must therefore indicate the same at all times. They correspond exactly to the distant and home signals now used almost universally in signaling systems, automatic and otherwise, the function of the distant signal being to caution the engineer of an approaching train as tothe conditionof the home-signal, and thus' give him an opportunity, should the distant signal indicate danger, to bring his train under control, so that he may not run by the home-signalshonld it still indicate danger when he reaches it.

The full-line circuits of station E are the same as at station A, except that the branch which contains the governor-lilagnet passes through two contacts of .the governor, as previously stated. There is also another branch of the full line circuit which'runs from the contactpoints cb through signal b, and.

thence to signal 19 where it connects with the full-line circuit leading from b to relay b.

v This full-line branch has the efiect of placing signals 1) and b in multiple, which is usually the best method of connecting the two signals. Under some circumstances, however,

ment. These contact-points are connected to the dotted-line circuit leading back to the governormagnet of station A, which circuit is therefore normally open, and theirobject is to close this circuit when the train passes over the track-instrument. Since these contact-points are. brought together by the passing of the first wheel ofthe train over the track-instrument, if nothing were'interposed to prevent', the dotted-line circuit would be completed when the first wheel passed over the track-instrument and the signal a would be returned to safety; but at the time the first wheel passes over the track-instrumentthe main portion of the train is still in the block A B, and itis desirable that the signal a shall not be restored to safety until the train shall have completely passed over the track-instrument and out of the block A B, which the signal a. protects. line circuit from being completed while the train is passing over the trackinstrumenh'I employ the normally-closed contact-points ab, which are likewise part of the track-instrument and are operated by the depression of the rail-levers. They are separated by the depression of the rail-levers an instant before contact-points 0b are brought together and remain separated so long as the train is passing over the track-instrument, being closed again when the train has passed an instant before contact ob is broken, thus closing for an instant the dotted-line circuit. The means .by which the contact-points are operated to effect this result is fully described in the specification of my track-instrument referred to above. I

Before following out the dotted-line circuits it is necessary to consider one peculiarity in the adjustment of. the set of contact-points next to the magnet in each of the governors, this set of contact-points being the one to which the dotted-line circuit is connected.

The armature contact-point is adapted to make contact with two contact-pointswith one' when the armature is attracted to the magnet and with the other when the armature is down or away from the poles of the magnet. These c0ntact-points are continuity-preserving contact-points and follow the movements of the armature to some extent, and the adjustment is such that contact is made with .be hereinafter described, through the rail to 7, thence'to 8, to 9, to 10 at station A, through the magnet-coils of the governor to 11, to a dotted-circuit return-wire at 12, over the re-. turn-wire to 13, thence to 14: at one end of an To prevent the dottedinsulated section of the right hand rail, through the rail to 15, and thence to the positive pole of the battery. When the circuit is completed through the coils of the magnet of governor a the armature is attracted and rises, thereby closing the full-line circuits and restoring signal (1, to safety. The completion of the f ull-line circuits re-establishes the flow of the electric current from battery 1 through the coils of governor a and keeps the magnet energized after the dotted-line circuit is broken, this circuit being complete for only a very short time.

In making connections for the full-line and dotted-line batteries the poles of the batteries should be so connected with their circuits that during the instant when currents from both batteries are flowing through the coils of the governor-magnet both currents will flow in the same direction, so as not to neutralize each other.

As has been seen, certain sections of the track-rails are insulated from the rest of the track, the insulation being indicated in the diagrams by breaks in the line of rails, and these insulated sections of track form a portion of the system of electrical circuits. The left-hand rail has two of these insulated sec tions, one on each side of the track-instrument, with a central section containing the track-instrument. The right-hand rail has one insulated section, the ends of which match the extreme ends of the insulated sections of the left-hand rail. The purpose of these insulated sections is to prevent the clearing of signals in rear of a train when its stops over the track-instrument with the rail-levers between two trucks-21 a, with no wheel on them. Under these circumstances the effect on the track-instrument contact-points is the same as though the train has completely passed, and, without special means to prevent, the sig nals would be returned to safety by the completion of the dotted circuit through the contact-points ab and of), or their corresponding contact-points at other stations. The insulated sections of track prevent this by short-circuiting the dotted-line circuit through the wheels and axles of a car. For instance, supposing a train from A at station 13 to stop over the track-instrument b in such a position as to permit the rail-levers to rise between the wheels, then the contact-points are operated as though the train had left the block A B and the dotted-line circuit is for an instant completed, since the contact-points c?) are brought together an instant before contact-poinst oh'are separated; but some car of the train will then be on the insulated section of track between A and B, which insulated section is somewhat longer than a car and is placed as close as possible to the track-instrument, and the dotted-line circuit will be short-circuited between the points 7 and 14, thus preventing the magnet of governor a from being energized so long as the car stands on the insulated section.

\Vhere it is desired to arrange the system to work under what is known as the permissive block system, these insulated sections may be united into one insulated section extending throughout the block, as shown in Figs. 2 and 3, in the block lying-between the points of the double-point siding.

I have described thus fully the object and operation of the insulated sections of track in order that their function in the operation of the system may be apparent. ever, properly a part of the track-instrument and have been so described in the description of my track-instrument. In the application for my track-instrument I have also described a purely mechanical arrangement for accomplishing substantially the same result that the said insulated rail-sections accomplish, and which may be employed in this system; but in general I prefer the insulated railsections, and have therefore confined myself thereto in the drawings which form a part of this application.

Passing on to station 0, the full-line-circuit connections for the direction from A to C are the same as at station B. The dotted line circuit is slightly changed to provide for the clearing of signals when a train passes from the main line to the siding. Since when a. train passes onto the siding the effect on the signal-circuits, so far as the setting of signals to safety is concerned,should he the same as if the train had passed on into the block beyond 0, it is suificientto place a track-instrument d on the siding beyond the fouling-point and connect its contact-points cd and ad in multiple withthe contact-points so that the effect on the signals is the same whether contact oc'or ad is closed. Insulated sections of track are used on the siding to prevent the clearing of the signals in case the train does not pass completely over the track-instrument.

It should be noted that the insulated sections of track may serve the same purpose as the dotted-line circuit normally-closed contact-points-such as ch or cc-by short-circuiting the battery through the wheels of a car instead of breaking the circuit. Shortcircuiting the battery, however, has a very deleterious effect on it, and for this reason the contact-points 0b, 650., are employed to reduce so far as possible the necessity of shortcircuiting the battery.

For the direction from C to A the full-line circuits-at O are the same as on the right side of the track, except that the normally-closed contact-points 0d" of track-instrument (Z are placed-in series with the contactpoints cc" of track-instrument 0, so that the same signals are set to danger in the division A C whether a train enters the division from beyond O or from the siding at C; but, as will be seen, a train entering the division from the siding sets the signals to danger when thefirst wheels of the train pass over the siding track-instrument, and, consequently, be-

They are, howfore it reaches the main track. The dottedline circuits are the same as at B on the right.

hand side of the track. At B the connections are the same on both sides of the track. A, since it is the terminus of the line and there are no signals to set to danger, the

only circuits necessary are the dotted-line elearing-circuits.

' siderations: Suppose that two trains enter the division A O, one at A and the other at O, at the same instant. Then the train at A, passing over the track-instrument a, sets the signal a to danger as. a rear signal, and at the same time, by means of the dashed-line circuits, in a manner to be hereinafter described, sets to danger signals and c at C, also b and b at BL The train at C will likewise set to danger signals 0 and c at 0,1) and b at B, and a at A; but if the trains enter the division simultaneously, or nearly so, the engineer of each train will see the home-signal of that station at which he then is set to danger, and will yet suppose that it is his own train which has set the signal as a rear signal, whereas the signal may have been set as a front signal by the train at the other end of the division. In this way, if there were no intermediate signal-station B, the trains might come into collision. This confusion of signals I avoid by the use of the special front signals, which are setonly by trains moving in the direction opposite to that of the trains which they are to warn. Thus atrain enterin the division at A sets to dan er si nal a a g M, does not change the condition of signal a and sets to danger signals 0 c and c at O and b b and b at B. In like manner a train entering at 0 sets to danger only signals 0 and c at C, while it sets signals a and a at A and b, 12 and b at B. Therefore if the engineer of a train entering the division A O at A should see not only signal a but also signal a go to danger he is thereby warned that at the same instant a train is also entering the division at O, and confusion is thereby rendered impossible.

Signals a and a and the others like them, are really separate signals, but since they are always together they may be mounted as separate signal-blades in the same signal-box or on the same signal-pole, and in my application'for Letters Patent for electric railwaysignals, Serial No. 441,480, I have shown how these two signals may be combined'in this manner., Itwill be evident that it is not essential in order to avoid confusion that the regular home-signals, as well as the special front signals, should be set as front signals;

but, as will be seen,no objection exists to operating the home-signals as front signals, and in my signal above referred to, in which both blades are within one case,it is essential that both blades be operated as front signals, and I have therefore shown the circuits so arranged that both signals are set as front signals; but ifit should be founddesirable aslight change in the connections is all that is required to have only the special front signal operated as a front signal. This may be'accomplished by making the front relay break the circuit of only the distant or caution signal, as b',without affecting the circuit of the home-signal, since it is evident that the same distant signal answers equally well for both rear and front signals. In my description of the signal referred to I have described how the front relays may be combined with the gov erning-magnets of the special front signals by providing the armatures of those magnets with contact-points. \Vhere my signal is used in connection with this system I considerthis double use of the governing-magnet very desirable, since it reduces the number of electromagnets required.

. The three most importantclasses of signals used in my system-via, distant, home, and, special front-should be distinguished in some way from each other by the color, position, or

form of the blade, so that they may not be mistaken for each other. The function of the distant signal is purely cautionary, while home and special front signals are properly danger signals, except where trains are run underwhat is known as the permissiveblock system, where these siguals likewise become cautionary, but indicate the necessity of great caution; but even in the permissive-block system the special front sig- IOO nalsshould be held to indicate danger at 1 through the first contact of the governor a to signalb, thence through the magnet of relay b"to the first armature-contact of governor I), through that contact if the arma ture be up to signal-magnet c thence to the magnetof relay 0", and thence by returnwire to battery 16. The lower contact-point of thefirst contact of governor b is likewise IIO connected to the return-wire at 17. It will be seen that when a train passes over track-instrumenta in the direction from A to 0, break ing contact 0 a and causing the armature of governor a to fall, this dashed-line circuit is broken, setting to danger signals b and c and allowing the armatures of

relays

5 and and 0" to fall, thereby breaking the signalcircuits which pass through their contactpoints, and setting to danger signals 12 ,1), 0, andcibut nota'iifectiugthegovernors. \Vhen the train has passed on to B, thus causing the armature of governor Z) to fall, and has raised the armature of governor a, a dashed -line circuit is completed from battery 16, through the first contact of governor a to signal I), through the magnet coils of relay 11"", through the first contact of governorb to 17, and thence by return-wire back to battery. The other dashed-line circuit runs from battery 18 at station 0 through the first contact of governor c to signal thence through the inagnet-coi1s of relay 1) through the first contact of governor b' to signal (L3, through the magnet-coils of relay a" to a return-wire, and thence back to battery 18. The lower first-contact point of governor b is connected to the return-wire at '19. The operation of this circuit is the same as that of the circuit of battery 16.

At station 0 there is still another dashedline circuit-battery 20, the circuit. or which passes through the first contact of governor 0. Another dashed-line circuit passes through signal 0, signal (1, and relaymagnet 0. Both of these circuits properly belong to the block beyond 0 and correspond exactly to the dashed-line circuits at station A. The signal (1 is a special siding-signal, the object of which is to warn the engineer of a train on the siding if there is a train on the block beyond O and coming toward 0.

In Figs. 2 and 3, which, as previously explained, are to be regarded as one continuous diagram, I have shown an application of my system to a double-point siding of such length and importance as to require the most conr plete signal system. The siding is of medium length and is provided with an arrangement of signals designed to fully provide for every possible train movement; but, as will be hereinafter described, the arrangement of signals here shown may be modified, as required, in order to accord better with the length of the siding, the trafiic of the road,

and other conditions that will be mentioned, where these conditions differ from those presupposed here. In these figures a: and y are the rails of the main track, at and y the rails of the siding, F and I signahstations at the two ends of the siding, and E and K advancesignal stations at either end, the purpose of which is to stop switching between stations F and I when a train reaches either of the advancc-stations or to stop an approaching train at the advance-station should a train be approaching it from the siding-stations. The sections of track between stations E and F and I and K constitute each a division for the direction approaching the siding, but only a block for the other direction, leaving between them a division F I. The circuits at E and K do not depart from the ordinary except for a change in the signal-circuits at station E, which does not affect the operation of the signals, and which will be hereinafter de scribed. At stations F and I and in the block between F and I there are some diffen ences in the circuits, due to the peculiar conditions there existing, which will be nowconsidered. These differences are principally in the full-line circuits, which here are not local circuits, but connect stations F and Lthough there are one or two slight changes in the dotted-line circuits.

Considering, first, the full-line circuits and beginning at station F on the right-hand side of the track, one circuit begins at the positive pole of battery 30, runs through the normallyclosed contact-points cf 10 the fifth contact of governor f, thence, if the governor-armature be up, through the coils of the governormagnet to 31, thence through the third governor-contact to the negative pole-of battery 30. This circuit, it will be seen, is the ordinary local fullline circuit without the branches for the signals f and f of station F, which are in a circuit, the battery of which is at station I, but which passes through the fourth contact of governor f, so that these signals are set to danger by the fall of the armature off. 'Leavingforthe moment this last circuit and taking up the full-line circuit on the left side of the track at station F, it runs from the positive pole of battery 30 through normally-closed contact'points of of track -instrument f, through normallyclosed contact-points cg" of the siding-track instrument 9 to 32, where it divides, one branch going to the fourth contact of governor f, thence through the coils of the governor-magnet to 33, and through the second governor-contact to 34. The other branch runs from 32 to 35, where it again divides, one branch going through signal'f to 36. The other branch from 35 runs to 37, thence, in Fig. 3, to 38, where itdivides, one branch going through signal 1', which, though operated by a full-line circuit, is really a special front signal, thence to 39,where it again joins the other branch from 38, which branch will be hereinafter described, thence to 40, to all, in Fig. 2, and thence through the second contact of governorf to 36. The two branches at 36 unite over a common return-wire, which runs through the contact of relay f and through the third contact of governorf to 34, where it unites with the first-mentioned branch of the full-line circuit over a common returnwire to the negative pole of battery 30. The remaining branch of this circuit runs from 38, in Fig. 3, to 42, where it divides, one branch containing signal F, the other branch containing signal t the two branches uniting at 43, thus placing signals '5 and i in multiple, and running through the fourth contact of governor t'" to 39, where it unites with the other branch from 38, aspreviously mentioned. So far as the actual connections are concerned, these circuits just described are in effect the ordinary signal-circuits, such as the circuits shown at station K, but with three distant-sig- ,-nals i tiandt, instead of one, all connected Signals f and false indicate great caution rather than'absolute danger.

The full-line circuits of station I are similar to those of station F, that circuit of sta- "tion F previously mentioned as running track between the points of the siding.

through. the second contact of governor f, which, being part of a circuit corresponding exactly to the circuit just described, as starting on the left side of the track at station F. Signals f,f ,f t and 2' correspond, respectively, to signals 5", i t ,f and f Signals g and h are special siding-signals, placed each at one end of the siding and differing'in no respect in function from signal (1' at station 0, in Fig. 1, the only difference in their con-' nections being that both g and h are each in a separate circuit having its own battery and passing through a contact of a governor at the opposite end of the siding from the signal which it controls, a plan which, if de; sired, may be adopted for signal at.

The dotted-line circuits at stations F and I are only slightly different from those at stationO, the diiterences being caused by the fact that the entire length of the rails between stations Fand I constitute insulated sections of track and form a part of the dotted-line circuits. Taking the circuit at station F, it runs from battery 44 through the normallyclosed contact-points cf to 45, thence to 4.6 at

one end of an insulated section of the'lefthand rail, thence to 4:7, to 48, to 49, at station E, to 50, to the third contact of governor 6', through that contact, if the armature bedown, to the governor-magnet coils,'thence to 51, to 52, at station F, to 53 at one end of an insulated section of the right-hand rail, to 54, to the normally-open contact-points of, to 55 and back to battery. A branch runs from contact-points of to 56 on the left-hand siding-rail, the part to which this Wire isconnected being in electrical connection with the right-hand rail of the main other branch runs from the negative pole of the battery to the normally-open contact points of and then to the magnet'of governor f, being also connected at 60 .With the leftshould the train stop over the track-instrumentf, battery 4-1 will be short-circuited between the rails of that portion'of the main track between the siding-points at the instant its circuit is completed through the closing of contact of an instant before contact 0 is broken,.and clearing of the signals will thus be prevented. Contact points 0g of the track-instrument g are placed in multiple withcontact-points of of track-instrument f by a wire leading fro m 55 through contact 0g to 57, through the siding-rail to 58, and thence to 59. v

The dotted-line circuit-connections of station I are the same as those of station F.

At station E is shown a modification of the signal-circuits by which the home and distant signals are placed in series instead of in multiple, as is the case at the other stations, an

arrangement that may be of advantage under some circumstances. The circuit runs from battery 21 through the normally-closed contact-points cc of track-instrument e, to the third contact of governor e, thence through the coils of the magnet of governor e to 22, where it divides, one branch going to signals 6 and e and to the upper contact-point of relay 6', thence through the armature contact-point to the second contact of the governor and. back V to battery. The other branch from 22 goes to the lower contact-point of relay' 6'. This relay c has two continuity-preserving contact-points engaging with one armature contact-point,'the adjustment being such that when the armature rises or falls contact is made with one contact-point before contact with the other is broken. The operation of this circuit is the same as that of the other full-line circuits where the signals are in multiple. The branch from 22 to the lower contact-point of relay e is to prevent the magneteircuit'of governor e. from being broken by the fall of the armature .of relay 6, which would make it impossible for the signals to be returned to safety by the com pletion of the circuit through the magnetcoils of relay e Before referring to Figs. 4, 5, 6, and 7, which show my system ofsignals applied to a doubletrack railway, I will describe the operation .of the system when applied to a single-track railway.

(Shown in the figures already described.) The operation of the double-track signals will be described separately.

The'operation of my system of signals, as applied to a single-track railway, is as follows: Taking first Fig. 1, and suppo'singa train to enter the division A G from A when the rail-levers of the track-instrument are depressed, the contact-points ca are separated, breaking the full-line circuit,thus allowing the armature of governor a to drop and setting to danger signal a as a rear signal to protect the rear of the train from any other train which may desire to follow. The fall of the armature of the governor breaks the dashedline circuit of battery 16, setting to' danger signal 12 causing the armature of relay b"" to drop, therebybreaking the signal-circuits passing through the contact-points of that relay and setting to danger signals b and b ICO IIO

setting to danger signal and causing the armature of relay 0"" to fall, thereby setting to danger signals 0 and 0 The division is thus completely closed to trains desiring to 5 enter it at either 0 or A. Should the train, after entering at A, desire to back out at A again, when in its backward movement it passes over track-instrument a, the dottedline open-circuit contact-points on" will be closed and the contact-points ca separated, and when the train has passed Completely over the track-instrument the contact ca is closed an instant before the contact 0a" is broken, thus completing momentarily a ciri5 cuit from the dotted-line circuit-battery at A through contacts ca and out", and through an insulated section of rail to the magnetcoils of governor a", and thence through the third contact of governor a to 11, and by return-wire to battery; Should the train stop over the track-instrument with the wheels in such a position as to allow the rail-levers to rise and by operating the contact-points complete the circuit momentarily, the battery will be short-circuited by current passing through the wheels and axles from the insulated section on one side of the track to the insulated section on the other side of the track, thus preventing the raising of the armature of governor a until the train has passed completely out of the block A 13. The raising of the armature of governor a completes the dashed-line circuit of battery 16 and restores to safety signals b b b 0 c and c. The raising of the armature likewise completes the full-line signal-circuit at station A, thus restoring to safety signal a Supposing the train to again enter the division A C at A, setting to danger, as before, signals of, b b b 0", c and c, and then to pass on over the division, when it reaches signal-station B, it operates track-instrument b,breaking contacts oh and cl) and closing contact 01). The breaking of contact ob breaks the full-line circuit, setting to danger signals 11 and b and causing the armatures of governor 1) to fall. over the track-instrument the contact 01) is closed an instant before contact 011' is broken, thus completing the dotted-line circuit as follows: from the negative pole of battery 5 through contacts cl) and ob to 6, through the rail to 7, thence to 8, to 9, to in station A, through the magnet-coils of governor a, through the third governor-contact to 11, to 12, and over a return-wire to 13, to 14:,thence through the rail to 15, and to the positive pole of battery 5. The completion of this circuit raises the armature of governor a, thus reestablishing the full-line circuit through the coils of the governor-magnet andretaining the armature up after the dotted-line circuit is broken at contact ob. The raising of the armature completes the circuit of the signal a, also the dashed-line circuit from the negative pole of battery 16, through the first contact of governor a, to signal I), through the mag- When the train has passed net-coils of relay 13" to the first armaturecontact of governor b, thence through the lower first contact-point to 17, and thence by return-wire back to battery. The com plction of this circuit restores to safety signal I) and raises the armature of relay 12"", thereby completing the signal'circuit passing through that relay and restoring to safety signals b and N. The train is thus free to back again after passing station B without having to dis regard any danger-signal. Should the train stop at station B with part of the train still in the block A B, and with the wheels in such a position that the rail-levers of track-instrument 1) may rise, thereby operating the contact-points of the track-instrument, and, since contact 01) is closed an instant before contact 01) is broken, completing the dotted-line circuit momentarily,the battery 5 will be shortcircuited between points '7 and 14, the current passing across the track through the wheels and axles of a car, thus preventing the raising of the armature of governor a. Passing on to station 0, when the train passes over track-hr strument c, it sets to danger signals 0' and c and causes the armature of governor c to fall, thereby breaking the circuit of battery and setting to danger the front signals in the division beyond 0 and completes the dotted-line circuit, thus raising the armature of governor b and restoring to safety signals b, 12 0", c and 0 thus leaving the division A 0 open from end to end. Should the train, instead of passing outof the division at C, enter the siding there, it will pass over sidingtrack instrument d, separating con tact-points cd and closing contact 061', and when the train has passed completely over the track-instrument (1 and so has left the main track clear the contact 061 is closed an instant before contactocl is broken, completing the dotted-line circuit through the coils of the governor-magnet of governor bflas follows: from open circuit-battery at 0 through contact-points co, cd, and 0d, through the right-hand rail-section of the siding and the left-hand rail-section of the main track, and through the dotted circuit-conductor to station B,throngh the magnet of governor b, and through the fourth contact of governor b, the armature of which is down, to the return-conductor, and thence back to battery, thus restoring to safety all signals in the division A 0 yet at danger.

When the train passes from the siding to themain track, it will break the contact ad", which is in series with the contact cc", causing the armature of governor c to fall and setting to danger signals c a, 11 ,12 b, a, and a The operation of the signals for trains going from O to A is in all respects the same as for trains going from A to O.

The necessity for the special front signals will now be seen. WVhen a train enters the division A G at A, it sets to danger signal a thereby protectingits rear and assuring the engineer that the signal-circuits are in work-