US904116A

US904116A - Railway block-signaling system.

Info

Publication number: US904116A
Application number: US36692407A
Authority: US
Inventors: Harry M Coulter
Original assignee: Individual
Current assignee: Individual
Priority date: 1907-04-08
Filing date: 1907-04-08
Publication date: 1908-11-17
Anticipated expiration: 1925-11-17

Description

H. M. GOULTER. RAILWAY BLOCK SIGNALING SYSTEM.

Patented Nov. 17, 1908.

- 4 SHEETS-SHEET 1.

APPLIUATION FILED APR. 8, 1907.

n4: NORRIS PETERS cm, WASHINGTON, n. c.

H. M. GOULTER. RAILWAY BLOGK SIGNALING SYSTEM. APPLICATION rum) APR. 8, 1907.

904,1 1 6. Patented Nov. 17, 1908.

(\2 4 SHEETS-SHEET 3. IP

L1 N i f H. M. GOULTER.

RAILWAY-BLOCK SIGNALING SYSTEM.

Patented Nov. 17, 1908.

4 SHEETS-SHEET 4.

rap-

I f6 77 Gay/Zia)" UNITED STATES PATENT OFFICE.

HARRY M. GOULTER, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO ALFRED STROMBERG, OF CHICAGO, ILLINOIS.

RAILWAY BLOCK-SIGNALING SYSTEM.

To all whom it may concern:

Be it known that I, HARRY M. COULTER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Railway Block-Signaling Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

The invention upon which I desire to se cure Letters Patent is in general an improvement upon the railway block signaling system described and claimed in United States Letters Patent No. 794,784.- granted to me on July 18th, 1905.

The improvements which constitute my present invention are directed toward the simplification and increased efficiency of the system set forth in my earlier patent.

The system of the present application dispenses with the need of ground return circuits; it eliminates many of the sources of current supply which are shown in my earlier application; it provides means for maintaining the display or actuation of the cab signals until they are restored to their normal condition by a positive act upon the part of a trainman; the form of stationary and moving track contacts is improved, and the circuits are improved in various respects which will more fully appear from the following detailed description.

I have illustrated in Figure 1 of the accompanying drawings the track and signaling circuits of my invention; Fig. 2 illustrates the circuits and mechanism placed upon a locomotive and adapted to cooperate with the signaling circuit shown in Fig. 1; Fig. 3 illustrates a modification of the track and controlling relay circuits; Fig. 4 shows diagrammatically the placement of the moving contacts upon the engine tender; Fig. 5 shows in side elevation the track contacts and their supports, and Fig. 6 is an enlarged view of one of the track contacts.

As an aid in understanding the circuit drawings, it may be said at the outset that the preferred embodiment of my invention comprises a signaling device carried by and upon a locomotive, these devices responding to the flow of electrical currents. hen a current of one strength flows through the Patented Nov. 17, 1908.

Serial No. 366,924.

rents of differing strength flow. through the set of apparatus. vided into a series of blocks. contacts are placed along the side of each block of the track in such a manner as to make electrical connection with cooperating contacts carried by the locomotive. The track and signal controlling circuits cooperate to establish circuits leading from the track contacts, the character of the circuit leading from any set of track contacts corresponding with the condition of traflic in the nearby blocks of the track. Each block of the track is equipped with a track circuit which includes the winding of a controlling relay. The controlling relays determine the character, as, for example, the amount of re sistance in the circuits leading from the track contacts situated in the neighboring blocks.

With this preliminary explanation and reference to Fig. 1, it will be understood that the series of blocks lettered A, B, C, D and E are each equipped with a source of current, as, for example, a battery of

gravity cells

11, 11. One of these gravity batteries is connected in bridge across the two rails at one end of each block. Near the other end of each block the controlling relays are connected with the two rails as shown. These cont-rolling relays are designated by the nu meral 13 to which a letter corresponding with the associated block is appended. It will be seen that current flows normally from the positive pole of the track battery through one rail from one end of the block to the other, thence through the winding of the associated controlling relay, (these relays being lettered 13 13, 13, etc), and back through the other track of the pair and thence to the negative pole of the track battery. The controlling relays are, therefore, normally energized and maintain their armatures in the attracted position shown in Fig. 1 of the drawings.

If through any accident one of the rails of a given block becomes broken, the electrical circuit through the associated controlling relay is opened, and the interruption in the flow of current causes the relay armatures to fall back to their abnormal position. So also the presence of a car truck on the two rails of any one block causes the winding of the associated controlling relay to be short-circuited on account of the low resistance of the circuit afforded through the The railroad track is di- Suitable track wheels and car axles, and this condition also will cause the controlling relay to be deenergized.

Before attempting to trace the signaling circuits, it may be well to state that Fig. 1 shows a single track railroad equipped with circuits for block signaling in both directions,that is to say, the presence of a car truck as indicated in dotted lines in block C, will cause the display of suitable signals in both directions. The track contacts at the far side of the track, as shown in Fig. 1, are used in signaling trains coming from the right, While the contacts shown at the near side of the track are used in signaling a train coming from the left. The track contacts for each block are located in pairs and form the terminals of circuits in which suitable resistances are connected. The signal controlling relays determine the resistance in each of the signaling circuits in a manner depending upon the condition of the trafiic in the associated block. The drawing shows each block equipped with three pairs of track contacts on either side of the track and lettered respectively to correspond with the designation of the block itself. Thus the outgoing contacts of block E at the far side of the track are lettered e, 6, while the return contacts are lettered e 6 On the near side of the track the out-going contacts for block E are lettered e 6 while the return contacts are lettered e 6 I have designated the various parts which are directly associated with each controlling relay with a numeral to which is subjoined a letter corresponding with the designation of the block whose track circuit controls the operation of the controlling relay. Thus the armatures of the controlling relay are lettered respectively 14 and 15, 14 and 15, etc. The front contacts with which the armatures numbered 15 normally make connection, each bear the numeral 16. The associated back contacts are numbered 17. Each of the armatures bearing the number 14 is provided with two back contacts munbered respectively 18 and 19. Connected with the armatures 15 I have shown resistances numbered 20 and 21 While another resistance 22 is connected in a circuit between the front contact 16 and the common return wire R.

Each pair of track contacts constitute under normal conditions the terminals of a high resistance circuit,for example, a circuit may be traced from any one of the track contacts 6 through the wire which leads by way of the resistance 20 to the armature 15, thence through the front contact 16 and the resistance 22 to the common return wire R and thence back through the wire e to the return track contact 6 It will be noted that this circuit contains two resistance coils, the resistance of which may be made alike or different and of an alnoi'lnt appropriate to the actuation of the instrumentalities hereinafter to be described.

If due to a break in the track circuit of the block C or due to the presence of a truck upon the track in block C the controlling relay 13 becomes deenergized, then the armatures 14 and 15 will fall back into the abnormal positions indicated by the dotted lines. Such a deenergization of the controlling relay reduces the resistance of the circuit just traced as will be made apparent by following the circuit from the track contacts e by way of the resistance 20 to the armature 15, thence by way of the back contact 17, the common return wire R and the return wire 6" to the return contacts 6 This circuit now contains only one resistance, namely, that lettered 20. Thus, it will be seen that the presence of a truck in the block C changes the signaling circuit which terminates in the contacts 0, c from its normal condition into a condition in which the resistance of this circuit is reduced.

Since the locomotive is equipped with instrumentalities differentially affected by the resistance of the circuit terminating in the track contacts, it will be apparent that a locomotive when coming from the right and reaching block E may receive a signal to indicate that there is an obstruction or a break in the second block in advance,-that is, block C.

If the train approaching from the right enters block D and establishes connection through the track contacts d, al it will find a circuit in which both resistances have been cut out. This will be made apparent by tracing the circuit from the contacts cl through the wire leading to the contact 19 and thence through the armature 14, the armature 15, the back contact 17, the common return wire R and the return wire cl to the track contact al The instrumentalities on the locomotive are adapted to respond differentially to this second reduction in the resistance of the signaling circuit, providing the engineer with. a distinctive signal to apprise him of the fact that there is an obstruction or break in the next succeeding block.

It will be unnecessary to trace these circuits for each of the blocks, for they are in all respects duplicated over and over again for each of the blocks of the system. The circuits are such that under normal conditions the controlling relay for each block establishes a circuit of high resistance terminating in the track contacts two blocks distant. Upon the deenergization of any controlling relay, the track contacts two blocks distant are provided with a circuit of decreased resistance, while the track contacts in the next adjoining block are provided with a circuit of still lower resistance.

When, as shown in Fig. 1, a single track is wire a to the track contacts a provided with the block signaling circuits in order to signal trains running in both directions, the track contacts a and a b and 79 etc., are likewise made the terminals of circuits whose resistance is controlled by the controlling relays numbered 13. Thus, for example, under normal conditions, a circuit may be traced from the track contacts a through the wire leading by way of the resistance 21 to the armature 15 and thence through the contact 16, the resistance 22, the common return wire R and the return This circuit, it will be noted contains the two resistances 21 and 22. WVhen the presence of a car or train on the track which constitutes block C causes a deenergization of the controlling relay. 13, one of these two resistances is cut out of the signaling circuit which leads from the track terminals at the near side of block A, for upon tracing the circuit from the contacts a it will be seen that current has now to flow only through the resistance 21, the armature 143, the back contact 17 the common return wire R and the return wire a in order to reach the contacts a If, therefore, a train is standing or moving in block C, any other train approaching from the left and making electrical connection with the contacts a a will be provided with a signaling circuit of lower resistance than would be the case if block C were clear. The train approaching from the left may proceed under reduced speed into the block D, where if the train or obstruction has not been removed from the block C, a signaling circuit of still lower resistance will be provided for actuation of the signaling device located upon the moving train. This will be made apparent by tracing the path of current from the track contacts Z1 through the wire which leads to the back contact 18 and thence through the armature 14, the armature 15 contact 17 the common return wire R and the return wire Z) to the track contacts 6 In this last signaling circuit there are no special resistances whatever. It will be seen, there fore, that my invention provides signaling circuits and electromagnetic mechanism, such that the presence of a truck in any block or a break of the track in any block will cause a certain reduction in the resistance of signaling circuits running in both directions and terminating in track contacts two blocks distant, while at the same time the deenergization of the signal controlling relay will establish circuits of still lower resistance terminating in the track contacts of the next block in both directions.

I have already referred-to the fact that the instrumentalities carried upon the moving locomotive are adapted to respond differentially in accordance with the condition of the signaling circuit terminating in the track contacts with which the locomotive circuit makes electrical connection. The 10- comotive circuit and apparatus is shown dia grammatically in Fig. 2. It consists essentally of three signal relays, each numbered 25 and provided respectively with indices t, is and .9 corresponding with the respective purposes of the signal relays, the first of which controls the test signal, the second, the caution signal, and the third, the stop signal. The corresponding parts of these three relays are similarly numbered, but in each case provided with an index corresponding with the function of the relay with which it is associated. Each relay is provided with an armature numbered 26 adapted upon attraction to make connection with the associated front contact 27. Each relay armature controls an electrical circuit through an associated signal lamp 28 and a signal bell 29. The test lamp may conveniently have a globe of one color,-for example, white, while the caution lamp and full stop lamp may be colored blue and red respectively. In like manner the signal bells may be provided with gongs of different tones or may be made to ring in charac teristically different ways.

As indicated in the dra ring, the retracting springs of the three signal relays are placed under different tensions in order to make the relay differentially responsive to currents of difiering strength. This differ ence in the adjustment of the relays may be augmented by providing them with windings of different resistances and numbers of turns. The adjustment is such that the flow of a small current through all of the relay windings will energize the relay 25 sufficiently to cause the attraction of the armature 26; but the armatures 26 and 26 will not be attracted. It is, in fact, preferable to make the adjustment of the caution and full stop relays such that their armatures will not be retained in the attracted position even though they be brought into such position during the flow of current suiiicient to cause the attraction of the armature of the test relay 25K in a similar manner the adjustment of the full stop relay '25 is made such that it will notbe actuated by a current of intermediate strength which is, how .ver, strong enough to cause the actuation of the caution relay 25 It is only tee flow of a current of maximum strength which will suflice to actuate the armature of the full stop relay.

With this explanation it will be readily understood how the locomotive circuit cooperates with the signaling circuits of Fig. 1 to furnish the engineer with signals by means of which he may determine the condition of the track either one or two blocks ahead. A suitable source of current, as, forin circuit with the main windings oi the signal relays, the terminals of this circuit being in the form of contact rails G and H which are mechanically attached to but electrically insulated from the tender of the engine, as best illustrated in Fig. 4. These contact ails are placed at such a height and in such position that they will register with the pairs of track contacts 0 and 0 (Z and (Z etc., while the locomotive is passing such contacts. The pairs of track contacts may conveniently be located a quarter of a mile apart, and if the blocks are a mile long, there will be four or five pairs of track contacts to a block. II" we consider a train approaching from the right and reaching olock E under normal conditions, the moving contacts G and H will make electrical connections respectively with the track con tacts e and 6 It will be remembered that under normal conditions the signaling circuit terminating in these track contacts was one containing two special resistances 20 and 22". It will be only a limited current which the storage battery L will be able to force through this signaling circuit and the main windings of the signal relays 25. The adjustments are made such, however, that this small current will cause the attraction of the armature of the test relay, causing the momentary illumination of the test lamp 2S and a stroke of the test bell 29, the current for the operation of these signaling devices being supplied through an appropriate circuit from the local battery M. The current which the battery L forces through this normal signaling circuit of high resistance is, however, insufficient to cause the actuation of the armatures of either the caution or the full stop signal relays. The engineer is, therefore, provided with a test signal which is repeated four or live times, or as shown in the drawings, three times during the passage of each block. If there is a train or a broken rail in block C, when the approaching train reaches block E there will be a corresponding change in the resistance of the signaling circuit which terminates in the

track contacts

6, 6 due to the deenergization of the controlling relay 13, as previously explained. The deenergizati on of this relay serving, as it does, to cut out part of the resistance in the signaling circuit which terminates in block E, the connection of the contact rails G and H with the track contacts 0 and 0 will cause the flow of a current of intermediate strength through the main windings of the signal relays located upon the moving train. This current, as previously explained, will be sufficient to actuate not only the test relay 25 but also the caution relay 25. The adjustments are made such, however, that even this current of intermediate strength will not be sutlicient to cause an actuation of the full stop relay 25 The battery L is able to cause the flow of a current of sutficient strength to actuate all three of the signal relays only when both resistances have been cut out of the signaling circuits. When, therefore, the moving train reaches the block D, a signaling circuit of very low re sistance will be provided in case the controlling relay 13 is still deenergized due to the presence of a car or train in the block C. In such case the armatures of all three of the signal. relays will be attracted to cause the actuation of their respective signal lamps and bells. The engineer will, of course, understand the repeated actuation of the test lamp and bell to mean that the block signaling system is in perfect operation.

Any defect in the system will either cause the flow of a large current when connection is made with the track contacts or will result in the flow of no current whatever. In the first case the engineerwill bring his engine under control or to a full. stop, just as though there were a train standing in an adjacent block. If, on the contrary he notes the failure of the test signal upon the passage of the pairs of track contacts, he will understand that there is some defect in the signaling system and that it cannot be relied upon. He will in this case also bring his train under control and proceed in such manner as to avoid danger of collision or derailment. The engineer will understand also that in the normal operation of the system he will receive not only the test signal but also a caution signal whenever he brings his train into a position two blocks distant from a train moving or standing upon the same track. He will, therefore, proceed with his train under control until. upon the passage of another set of track contacts, the absence of the caution signal indicates to him that the obstruction upon the second block in advance has been removed. In such event he may proceed again at full speed. If, however, the caution signal continues to be displayed whenever he passes a set of track contacts, he will continue to keep his train under control, and it upon passing into the next block the actuation of the stop signal relay shows that there is a train or a break of the rail in the next block in advance, he will bring his train to a full stop before passing into the next succeeding block of track.

It will be unnecessary to explain in detail that when a single track is blocked in both directions, as indicated in Fig. 1, the signaling mechanism will be actuated to indicate the approach of another train head on, the signals in this case being actuated in the engine cabs of both trains. It will be understood furthermore than when one train follows another in either direction, the block signallng system Wlll serve to lndicate to the engineer of the second train whenever the first train is less than three blocks in advance of the following train.

In order to make certain that the engineer will recognize and act in accordance with the display of the caution and full stop signals, I have shown in F 2 an auxiliary winding numbered 30 upon the cores of the relays 25 and 25 These auxiliary windings are respectively included in circuits containing normally closed spring switches numbered 31, armatures 32 and armature contacts 33. The

auxiliary armatures

32 and 32 are preferably adjusted so as to be attracted and released only when the main armatures of the same relays are attracted and released.

When, therefore, suflicient current flows through the signal relays to attract the armature 26, the auxiliary armature 32 will also be attracted to close a circuit through the auxiliary winding 30 and the normally closed spring switch 31 Current flowing through. this auxiliary winding will maintain the energization of the caution signal relay, even after the contacts G and H have broken circuit with the track contacts. The caution signal lamp and bell will continue, therefore, to be actuated until the engineer positively recognizes them and restores them to their normal condition by depressing the key 31 to open the circuit of the auxiliary winding 30 whereupon both armatures of the caution signal relay will be released and restored to their normal position, thereby opening the local circuit of the caution signal lamp and bell. In like manner the at traction of the armature 26 clue to the [low of a heavy current through the relay 25 will cause the closure of the circuit through the auxiliary winding 30 the flow of current through this circuit being maintained until the engineer recognizes the stop signal and depresses the spring switch 31 to open the circuit of the auxiliary winding of the full stop signal relay. This auxiliary equipment of the caution and full stop signal relays transforms them into what may be termed locking relays which upon actuation continue to act until unlocked and thus restored to their normal condition by the actuation of the associated buttons or switches. By virtue of this equipment there can be no excuse for the failure of an engineer to understand and appreciate the signals provided for the safe conduct of his train.

In order to test the engine equipment, I preferably provide a testing circuit which may be operated by the engineer before commencing a run or at any other time when he finds it desirable so to do. This testing circuit consists essentially of a resistance varying device connected with the moving contacts G and H. This is shown in Fig. 2 in the form of acircuit leading to a switch arm 32. This switch arm may be swung into a position to make electrical connection with any one of the

contacts

33, 34 or 35. The resistance 36 connected between the contact 33 and the moving contact G is equal to the normal resistance of the signaling circuits previously traced on Fig. 1- The resistance 3'? is equal to that of the signaling circuit in which the resistance 22 has been cut out by the denergization of the controlling relay. The resistance of the wire 38 which leads from the contact 35 is equal to that of the signaling circuit in which both of the resistances have been cut out. The resistance of this circuit is practically negligible, for when both of the resistances are cut out, the circuit is practically short-circuited.

In order to test the condition of the signaling devices 28 and 29, the signal relays 25", 25 and 25 and the circuits local to the engine cab, the engineer swings the switch arm 32 successively into connection with the

contacts

33, 34 and 35. When the switch arm makes connection with the contact 33, current will flow in the cab circuit in the same manner and with the same strength as it would when the moving contacts make connection with a pair of track contacts which form the terminals of a signaling circuit in its normal high resistance condition. Under these circumstances the apparatus should be actuated to cause the operation of the test signal alone. hen the switch arm 32 is brought into connection with the contact 34, both the test and caution signals should be displayed. \Vhen the switch arm 32 is brought into connection with contact 35, all of the signaling devices should be actuated in the same manner as when the engineer receives the full stop signal when running upon the road. If for any reason the signaling" devices do not operate in this manner when tested by means of this auxiliary test circuit, the engineer will be apprised of the fact that something is wrong, and the defect may be located and remedied.

In Figs. 5 and 6 I have illustrated in some detail the preferred form of the track contacts already referred to. These contacts take the form of brushes of steel bristles 4O embedded in a suitable back 41. The si naling circuits previously described terminate in the bristles of these brushes. Above each brush is mounted a protecting board or cover 42, and rubber cloth or other suitable flexible material is fastened around the edges of the cover 42 so as to protect the steel brush from rain, sleet or snow- The rubber cloth is, however, flexible, so that when the projecting contact rails attached to the locomotive tender approach the brush, the rubber cloth will be deflected, as indicated in dotted lines in Fig. 6, to permit the passage of the contact bar G or H as the case may be. After the passage of the contact bars, the rubber cloth will spring back into its normal position, as shown in the full lines. In Fig. 5 I have indicated the I-beam frame of a locomotive tender in dotted lines at 44. So also I have indicated in dotted lines the contact bars G and H in the posi tlon which they assume while passing under track contact brushes 40. The brush con tacts are suitably insulated at 45 from the fork-shaped support 46. This support is riveted or otherwise attached to an iron post 47, this post being simply a piece of pipe, to the upper end of which a cap 48 is screwed and the lower end of which is screwed into a suitable base plate 49, this plate being bolted in turn to a pair of

extended railroad ties

50, 50. This manner of constructing the contact-making devices may be reversed by attaching the elongated steel brushes to the sides of the locomotive tender while suitable posts along the right of way support contact bars like those which I have shown upon the locomotive tender. In either case the flexibility of the bristles of the brushes will permit considerable sidewise movement or displacement and still in sure the making of good electrical connection.

In Fig. 3 I have illustrated a modification of the track circuit which is particularly well adapted for use upon tracks which are laid in damp ground or where the ballast is such as to retain considerable moisture with the attendant danger of short-circuiting the two rails of the track. In Fig. 3 I have shown a single block of a railway in which, however, each of the rails is frequently divided by insulating joints I. Each of the insulated sections of the block is provided. with a track circuit comprising a battery 11 and a track relay 60. I have shown at 153* a controlling relay having functions corresponding with those of the controlling relays shown in Fig. 1, this controlling relay being provided with an energizing circuit leading from the battery 62 through the winding of the relay 13*. The current flowing in this circuit serves normally to energize the relay 13*, but whenever any one of the sections of the block shown in Fig. 3 is shortcircuited, the associated track relay 60 will be deenergized, thereby permitting the retraction of its armature to open the circuit which leads from the winding of the controlling relay 18 to the battery 62. Upon deenergization, therefore, of any one of the track relays, there will be a corresponding denergization of the controlling relay 13 for the same block. The operation of the system will, therefore, correspond with that previously explained in connection with Fig. 1. The advantage of this arrangement in certain cases will be apparent to those skilled in the art. Since each of the insulated sec tions of a given block is comparatively short, there will be little opportunity for leakage of current from one rail to another and by the use of a low voltage battery, it will be easily possible to control satisfactorily the operation of the track relays. By the use of this arrangement, the lengths of the blocks as determined for signaling purposes, will not be limited by the distance through which it will be possible sufiiciently to insulate the rails from one another.

It will be apparent that many modifications of my invention may be made without departing from the spirit thereof, and I do not, therefore, wish to be limited to the precise disclosure herein contained. The scope of what I claim as my invention is indicated solely in the following claims for which I desire to secure Letters Patent:

1. In a railroad block signaling system, the combination with a series of blocks, of a controlling relay for each block, a normally closed track circuit in which each controlling relay is connected, a source of current in said track circuit whereby the electrical connection of the two rails of a block causes the deenergization of the associated controlling relay, suitable track contacts placed in each block, a signaling circuit extending from each controlling relay to the track contacts in the second block in each direction, two resistances normally included in each signaling circuit, switch mechanism adapted to cut one of the resistances out of the signaling circuit upon the deiinergizationof the controlling relay, switch mechanism adapted to short circuit the signaling circuit terminating in the next block in each direction upon the deenergization of the associated controlling relay, three signal relays carried by a locomotive, said signal relays being differentially adjusted, each to respond to currents of different strength, a source of current carried by the locomotive, said relays and said source of current being connected in a circuit terminating in moving contacts adapted to register and make electrical connection with the track contacts, a local sig nal circuit for each of said signal relays, an electric signaling device in each of said local circuits, a supplemental winding on one or more signal relays, each winding being included in circuit with a pair of normally open switch contacts controlled by the associated relay and adapted to be closed upon the energization thereof to maintain the attraction of the relay armature, and a normally closed manual switch in circuit with the supplemental winding or windings.

2. In a railway block signaling system, the combination with a series of blocks, of a controlling relay for each block, a normally closed track circuit in which said con trolling relay is connected, a source of current in said track circuit whereby the electrical connection of the two rails of a block causes the denergization of the associated v controlling relay, a signaling circuit extending from each controlling relay to the track contacts in the second block in each direction, two resistances normally included in each signaling circuit, swlitch mechanism adapted to cut one of the resistances out of the signaling circuit upon the deenergization of the controlling relay, switch mechanism adapted to short-circuit the signaling circuit terminating in the next block in each direction upon the denergization of the associated controlling relay, and a source of current and suitable differentially responsive signaling mechanism carried on a moving train and adapted to make electrical connection with said track contacts.

3. In a railroad block signaling system, the combination with a series of blocks, of a controlling relay for each block, a normally closed track circuit in which each controlling relay is connected, a source of current in said track circuit whereby the electrical connection of the two rails of a block causes the deenergization of the associated controlling relay, suitable track contacts placed in each block, a signaling circuit extending from each controlling relay to the track contacts in the second block to the rear, two resistances normally included in each signaling circuit, swjitch mechanism adapted to cut one of the resistances out of the signaling circuit upon the deenergization of the controlling relay, switch mechanism adapted to short circuit the signaling circuit terminating in the next block to the rear upon the deenergization of the associated controlling relay, three signal relays carried by a locomotive, said signal relays being differentially adjusted, each to respondto currents of different strength, a source of current carried by the locomotive, said relays and said source of current being connected in a circuit terminating in moving contacts adapted to register and make electrical connection with the track contacts, a local signal circuit for each of said signal relays, an electric signaling device in each of said local circuits, a supplemental winding on one or more signal relays, each winding being included in circuit with a pair of normally open switch contacts controlled by the associated relay and adapted to be closed upon the energization thereof to maintain the attraction of the relay armature, and a normally closed manual switch in circuit with the supplemental winding or windings.

4. In a railway block signaling system, the combination with a series of blocks, of a controlling relay for each block, a normally closed track circuit in which said controlling relay is connected, a source of current in said track circuit whereby the electrical connection of the two rails of a block causes the deenergization of the associated controlling ielay, a signaling circuit extending from each controlling relay to the track contacts in the second block to the rear, two resistances normally included in each signaling circuit, switch mechanism adapted to cut one of the resistances out of the signaling circuit upon the deenergization of the controlling relay, switch mechanism adapted to short-circuit the signaling circuit terminating in the next block to the rear upon the deenergization of the associated controlling relay, and source of current and suitable dili'erentially responsive signaling mechanism carried on a moving train and adapted to make electrical connection ith said track contacts.

5. In a rail 'ay block signaling system, the combination with a series of blocks, of a controlling relay for each block, a normally closed track circuit in which said controlling relay is connected, a source of current in said track circuit whereby the breaking of a ail or short-circuiting of the two rails of a block will cause the deenergization of the associated controlling relay, a signaling circuit extending from each controlling relay to suitable terminals in the second block to the rear, two resistances normally included in each signaling circuit, switch mechanism operated by each controlling relay to cut one of the resistances out of the associated signaling circuit, switch mechanism operated y each controlling relay to cut the other resistance out of the signaling circuit ter minating in the next block to the rear, and suitable electrical signaling crevices differ entially responsive to currents of different strength and adapted for connection with the terminals of the signaling circuits.

6. In a railway block signaling system, the combination with a se-ies of blocks, a signaling circuit extending from each block to the second block in each direction, a resistance normally included in each signaling circuit, suitable mechanism controlled in its operation by the condition of or upon the track which constitutes the associated block and adapted upon actuation to reduce the resistance of the signaling circuits extending from the associated block and terminating in the second block in each direction and to reduce still further the resistance of the signaling circuits terminating in the next adjacent block in each direction, and electrical signaling devices adapted for connec tion with the terminals of the signaling circuits.

7. In a railway block signaling system, the combination with a series of blocks, a signaling circuit extending from each block to the second block in each direction, a resistance normally included in each signaling circuit, suitable mechanism controlled in its operation by the condition of or upon the track which constitutes the associated block and adapted upon actuation to reduce the resistance of the signaling circuits extending from the associated block and terminating in the second block in each direction and to reduce still further the resistance or" the naling circuits terminating in the next adjacent block 11] each direct1on, a plurality of signal relays differentially responsive to currents of diiterent strength, and a source of current having a circuit adapted for connection with the terminals of said signaling circuits, and electrical signaling devices connected in local circuits controlled by the signal relays.

8. In a railway block signaling system, the combination with a series of blocks, a signaling circuit extending from each block to the second block in each direction, a resistance normally included in each signaling circuit, suitable mechanism controlled in its operation by the condition of or upon the track which constitutes the associated block and adapted upon actuation to reduce the resistance of the signaling circuits extending from the associated block and terminating in the second block in each direction and to reduce still further the resistance of the signaling circuits terminating in the next adjacent block in each direction, a plurality of signal relays diiterentially responsive to currents of different strength, and a source of current having a circuit adapted for connection with the terminals of said signaling circuits, electrical signaling devices connected in local circuits controlled by the signal relays, and a supplemental winding on certain of the signal relays, each supplen'iental winding being included in a local circuit containing normally open switch contacts controlled by the associated relay and a normally closed manual switch.

9. In an electric signaling system, the combination with three signal relays having main windings serially connected in circuit, said relays being differentially adjusted to respond to currents of different strengths, a supplemental winding for the relays responding to current of intermediate strength, and a supplen'iental winding for the relay responding to current of maximum strength, a local circuit for each of said supplemental windings, each local circuit including a normally closed, manual switch and normally open switch contacts controlled by the associated relay, and suitable signal devices controlled by each of the three relays.

10. In a track contact for a cab signaling system, the combination with a brush having depending metal bristles, of a cover for said brush, suitable flexible material attached to said cover and extending downwardly to protect the sides of said brush as and for the purpose described.

11. In a track signaling system, the combination with a supporting post, of a forklike bracket attached thereto, a pair of con tacts comprising brushes with depending bristles supported by and insulated from the fork-like bracket, acover for each of the brushes, and a curtain of rubber cloth attached to each of the covers and extending downwardly around the sides of the brushes to protect them from the weather, as and for the purpose described.

12. In a railway block signaling system, the combination with a series of blocks comprising a pair of rails insulated from the rails of the next succeeding block, a track circuit including a controlling relay associated with each block, track contacts located in each block, a common return conductor, a signaling circuit including the common conductor and extending from each cont-rolling relay to the track contacts of the second block in each direction, switching mechanism serving upon the actuation of each controlling relay to reduce the resistance of the signaling circuits terminating in the track contacts of the second block in each direction and serving also to reduce still further the resistance of the signaling circuits terminating in the next adjacent block in each direction, and electrically operated signaling mechanism adapted for connection with the track contacts.

13. In a railway block signaling system, the combination with a series of blocks comprising a pair of rails insulated from the rails of the next succeeding block, a track circuit including a controlling relay associated with each block, a common return conductor, a signaling circuit including the common conductor and extending from each controlling relay to the track contacts of the second block to the rear, switching mechanism serving upon the actuation of each controlling relay to reduce the resistance of the signaling circuit terminating in the track contacts of the second block to the rear and serving also to reduce still further the resistance of the signaling circuit terminating in the next adjacent block to the rear, and electrically operated signaling mechanism adapted for connection with the track contacts.

14. In a railway block signaling system, the combination with a series of blocks, of two signal controlling devices, each in a separate block, and two signal conveying paths, each path being adapted to convey signals to a different block, the actuation of the first signal controlling device serving to reduce the'resistance in the first of said paths and to reduce still further the resistance of the second of said paths and the actuation of the second signal controlling device serving to establish a similar low resistance condition in the first of said paths.

15. In a railway block signaling system, the combination with a controlling relay and a circuit therefor, a plurality of insulated sections comprising the rails which constitute a single block, a track relay and circuit for each of the insulated sections, and means whereby the operation of any of the track relays Will operate the controlling relay, such controlling relay adapted by its operation to change the resistance of a signaling circuit associated With said block, said signaling circuit being closed and of difierent resistance for each signaling condition.

16. In an electric signaling system, the combination With a plurality of signal relays connected in a common circuit, said relays being differentially adjusted to respond to currents of different strength a signaling circuit adapted for connection with the circuit in Which said signal relays are connected, means for changing the resistance of the signaling circuit to effect the differential actuation of the signal relays, an auxiliary test circuit connected with the terminals of the common circuit through the signal relays, and means for varying the resistance of the auxiliary test circuit to correspond With the normal variations in the resistance of the signaling circuit as and for the purpose described.

17. In a railway block signaling system, the combination with a series of blocks, of a signaling circuit extending from each block in each direction, a resistance normally included in each signaling circuit, mechanism controlled in its operation by the condition of or upon the track of such block, such mechanism adapted by its actuation to vary the resistance of the signaling circuits extending from such block, and electrical signaling devices adapted for connection With the terminals of the signaling circuits.

In Witness whereof, I hereunto subscribe my name this 5th day of April A. D., 1907.

HARRY M. COULTER.

WVitnesses:

LYNN A. WILLIAMS, FRED WV. KoEHN.