US901379A - Electric-railway system. - Google Patents

Description

w. ROBINSON. ELECTRIC RAILWAY SYSTEM.

APPLICATION TILED AUG. 18, 1907.

Patented Oct. 20, 1908;

2 BHEETS-BHEET 1.

THE NORRIS PETERS ca, WASHINGTON, a. c

W. ROBINSON.

ELECTRIC RAILWAY SYSTEM. APPLICATION FILED AUG. 13, 1907.

Patented 00t.20, 1908.

2 SHEETS-SHEET 2.

I INVENTOR- ruz umzms PETERS co. wAsn-mmou, 21c.

WILLIAM ROBINSON, OF BROOKLYN, NEW YORK.

ELECTRIC-RAILWAY SYSTEM.

Specification of Letters Patent..

Patented Oct. 20, 1908.

Application filed August 13, 1907. Serial No. 388,292.

' To all whom it may concern:

Be it known that 1, WILLIAM ROBINSON, a citizen of the United States, residing in Brooklyn, in the county of Kings and State of New York, have invented a new and Improved Electric-Railway System, of which the following is a specification.

My invention comprises an electric railway safety system in which the third rail or working contact conductor is divided into sections insulated from one another and nor mally disconnected from the source of working current.

fy invention embodies improvements in this connection hereinafter explained.

The nature of my invention will be understood from the description which follows, reference being had to the accompanying drawings, which form a part of this specification, in which Figure 1 is a diagram showing the circuit instruments and signals in elevation, partly in section, illustrating the use of the direct current in applying my invention to a rail road track; Fig. 2 is a vertical section through the line at, :r Fig. 1; and Fig. 3 is a diagram illustrating the application of my invention where both the direct and the alter nating currents are utilized.

A and O, represent the service or traction rails of a railroad track, in which the rail A is continuous and serves as a return for the cur rent of the generators D and F connected thereto, while the rail O is divided into sections a, l), c, d, e, insulated from each other as shown atf, g, h, i.

B represents a working or contact conductor or third rail divided into sections k, Z, m, a, 0, insulated from each other as shown at D represents a high potential or workingcurrent electric generator and E a feeder proceeding therefrom, while F represents another electric generator of lower potential current, and G a feeder proceeding therefrom. The generators D and F, respectively, have one terminal connected by branch conductors t, u, to the return rail A. The working current feeder E is normally disconnected from the third rail sections Z, m, a, as illustrated at the open contacts 1, 1; 2', 2. The lower potential feeder G however, is normally connected in multiple to the track sections b, c, d, preferably near one end of said sections, by the Wires 3, 4, 5. At the opposite ends of said sections the respective track relay magnets, 6, 7, 8, have one terminal connected to said respective track sections by the wires 9, 10, 11, and

their opposite terminals connected to the re- .turn rail A to the generator F, completing the relay circuits.

Referring now specifically to Fig. 1: The track relays 6, 7, 8, attracting their armatures 15, 16, 17, keep the secondary circuits 18, 19, 20, normally closed. Thus the secondary circuit 18, for instance, including the magnets 21 and 22, is normally closed at 23 by the relay 6 attracting its armature 15, whereby said magnets 21 and 22 are normally energized and attract their respective armatures. The magnet 21 attracting its armature 24 keeps the circuit 25 of the solenoid 26 normally open at the contact points 27, while the magnet 22 keeps the similar circuit 28 of the solenoid 29 normally closed at the contact points 30. In like manner the secondary magnets 31 and 32, being normally on closed circuit, the magnet 32 attracting its armature 33 keeps the circuit 25 r of the solenoid 26 on normally closed circuit at the contact points 34. In like manner also, the secondary circuit 19 being normally closed at 35 the magnet 36 thereln attracts its armature 37, thus keeping the circuit 28 of the solenoid 29 normally on open circuit at the contact points 38, while the magnet 39 attracting its armature 40 keeps the circuit 41 of the solenoid 42 normally closed at the contact points 43. Thus each solenoid. circuit has two switches, one of which is normally open and the other normally closed.

The solenoids 26, 29 and 42 are used to directly control the propulsion current switches o, 44, 45, for connecting the heavy working current from the feeder E to the working or third rail sections Z, m, n, and disconnecting the same therefrom. These solenoids or propulsion current switch magnets, therefore, are much heavier and more powerful than any of the other magnets heretofore described.

It will be observed that I take from the feeder G currents of three different degrees of strength or efhciency in the different cir cuits and magnets utilizing the same. Thus in the branch conductors 3, 4, 5, furnishing current to the track relays 6, 7, 8, I insert heavy resistances 46, since said relays require but a light operative current.

The magnets in the circuits 47, 18, 19 and 20 require to be stronger than the track relays controlling said circuits since the magnets in said circuits 47, 18, 800., control the circuits of the much heavier solenoids 26, 29, 42, which latter must have the greater strength required to control the opening and closing of the heavy working circuits from the feeder E, in view of the necessarily long gap in said switches 'l), 44, 45. Accordingly in said circuits 47, 18, 19, 860., connected to the feeder G at the points 48, I insertthe resistances 49, which are considerably lower than the resistances 46. In like manner I insert much lighter resistances 50, in the circuits 25, 28 and 41 of the heavy solenoids 26, 29, 42. The latter circuits have one terminal connected to the feeder G, as shown at 51, and the other terminal to the return rail A, as shown at 52. Thus we obtain from a single source of supply, or from a single feeder, a low strength current for the track relays, an intermediate current for the sec ondary or intermediate magnets, and a much stronger tertiary current for the heavier work of the solenoids in directly controlling the Working circuit.

53 represents a car or train provided with a driving motor 54, a controller 55 and contact brushes or collecting shoes 56 and 56 preferably at opposite ends of said car or train, and making running contact with the third rail B. The motor 54 has one terminal connected electrically to the car axle by the wire 57 and the other terminal to the controller 55 by the wire 58. The contact shoes 56 and 56 are connected to the controller by the wire 59, as shown.

The operation is as follows, assuming the train to be running from left to right, as in dicated by the arrow y; When the car or train enters upon the track section or block c, for instance, as shown, the wheels and axles short circuit the current from the relay ma net 7 which, thus denergized, releases its armature 16, thus opening the circuit 19 through the magnets 36 and 39 at the con tact points 35. The deenergizing of the magnet 36, releasing its armature 37, closes the circuit of the solenoid 29 at the contact points 38. The circuit through said solenoid is thus completed since its circuit is normally closed at the contact points 30, as described. Said solenoid 29 now actuates the switch 44, closing circuit between the contacts 60, 60, and thus connecting the working feeder E to the contact section m through the wires 61, 62, as shown, whereby the car or train 53 is supplied with working current as long as it is on the section or block a. The deenergizing of the magnet 39 as described, opens the contacts 43 in the circuit of the solenoid 42 at the beginning of the section (1 to the rear of the section 0 occupied by the car 53, consequently a following train approaching from the section a loses current the instant it enters upon the section d by drifting or etherwise, since the presence of the train on the section 0, controlling and automatically opening the switch 40 in the circuit of the solenoid '42, renders the admission of working current to the contact section at impossible. Furthermore, when the switch 45 is in its normal position, as shown, it makes connection between the contact points 63, 64, thus making electrical connection between the track return A and the contact or third rail section it through the conductors 65, 66, thus a train entering upon the section (Z with its controller closed, while a forward train occupies the section 0, is not only deprived of working current but circuit is closed upon its motors through said conductors 65, 66 and switch 45. It will be observed however, that upon entering the section or block (1, while the circuit is closed at 63, 64, between the return A and the section it, as described, the head of the train making electrical connection between the section a and return A, through its motors, closes the motor circuit of the train upon itself while the train is still picking up current from the preceding working section 0, through its rear collecting shoes or brushes 56*. I therefore insert a suitable resistance or impedance in the connection between the rail return A and the working section n, in the branch 65 or 66, preferably in the former, as shown at 67, since the opening of the circuit at 45, between the contacts 63, 64, will throw the impedance 67 entirely out of circuit, thus permitting the main circuit to be closed at 2, 2, without interference from said impedance. It will be understood that any desired amount or character of resistance or impedance, in any suitable form, may be inserted in this situation, thus protecting the motors and giving the train its initial stopping impulse in overcoming this resistance or impedance, when the motors are constructed and arranged to be converted into generators.

In Fig. 1 the resistance 67 is illustrated as consisting of a series of incandescent and arc lamps; at 68 as consisting of incandescent lamps; at 69 as embodying a suitable ohmic resistance 69 and an inductive resistance 69. A rheostat 70 is introduced by which greater or less resistance or im edance, as required, may be included in the ranch 71. In Fig. 3 an equivalent impedance, more fully de scribed hereinafter, is illustrated by choking coils 72.

It will be seen that by the means described a trainoccupying a section or blockwillprotect itself automatically from rear end collisions by compelling a following train to keep approximately the length of a section or block to its rear. It will be noted also that when a following train enters upon the section or block d as described, its wheels and axles short circuit current from the relay 8, which, releasing its armature 17 opens the circuit 20 at the contact points 73. It will be understood that the circuit 20 has precisely the same connections and adjuncts, and operates in the same manner, as the circuits 18 and 19 described. Thus a train stalled on the section (1 by the presence of a train on the section 0 protects itself automatically from rear end collision by arresting any train following it, at the entrance of the section 0. When the car or train 53 has moved forward to the section b, passing off the sec tion 0, the relay 7 is instantly energized by the removal of its short circuit, thus restoring the circuits connected with the section or block (Z to their normal condition and there by permitting the slowed or stalled train at the entrance of the section d to receive work ing current and proceed.

From the foregoing description it will be understood that a long series of trains may follow each other under close headway, in which case each train, however many there may be, will automatically protect itself against the too near approach of the next following train.

In Fig. 1 is illustrated an electro pneumatic or fluid pressure system of signals controlled by electro-magnets, the signal system operating automatically and simultaneously with the railway system, the latter controlling also the signal system, which adds additional safety and efficiency to the railway system as such. In this case the semaphore signal is kept normally in the safety or inclined position shown at by means of compressed air or other fluid, admitted to the cylinder 76 from the gas or air tank T, through the pipes 77. The admission of air to said cylinder is controlled by the valve 7 8, and this valve is controlled by the electro magnet 79. When said magnet is magnetized it opens said valve, admitting air to the cylinder and thus holds said signal in the inclined or safety position as its normal position, as shown at 75. When, however, a rain enters upon the section 0, for instance, short circuiting the track relay 7, as described, the latter opens the signal circuit at 35, thus demagnetizing the signal magnet of the signal 80. The spring 81 now closes the valve 78 and opens the exhaust at 82, thus permitting the escape of the air or gas from the cylinder'7 6. The signal blade thus released is now thrown into the horizontal position representing danger or caution, by its counter-weight 83 as indicated by the horizontal blade 84 of said signal 80.

It will be observed that the signal-controlling magnets 79, res ectively, receive current in multiple from t e feeder G through the branch conductors 85, 86, 87 in each of which is inserted the resistance 88, adjusted to give said magnets the re uisite strength to control the operation of t 1e signals. It is pointed out also that said signal magnets 79, respectively, have their opposite terminals connected in multiple to the respective circuits 18, 19 and 20 by the wires 89. Thus, when the circuit 19, for instance, is opened at 35, by the demagnetization of the relay 7, not only does this open circuit through the magnets 36 and 39, as heretofore described, but it also opens circuit through the signal magnet 79 connected to said circuit 19, thus closing the air valve 78, and opening the exhaust 82, thus allowing the counterweight 83 to swing the signal into a horizontal or danger position, as shown. These signals may be placed in any desired position relatively to the sections or blocks which they are designed to protect and may be of any suitable construction,a nd arranged to overlap or occupy any desired position relatively to each other, and may be used for block or station signaling or for any other purpose.

It is conceivable that under some conditions when a train is on a section a wandering current of high potential might reach the track relay 7, for instance, and close circuit at 35, thus interfering with the proper action of the secondary magnets 36, 39 and the signal magnets 79 under control of said relay. To obviate this possibility I introduce the magnet 90 in the working circuit 62 so that when working current passes over said circuit 62 said magnet 90 becomes magnetized and, attracting its armature 91, opens circuit at 92 in the circuit 19, that is, in the circuit of the secondary magnets 36, 39 and of the signal magnet 79, thus producing the same results as when said circuit is opened at 35 by the demagnetization of the relay 7. Manifestly, therefore, while a train occupies the section or and is using Working current it is immaterial whether the relay 7 is or is not magnetized, since the secondary circuit 19, which it controls, is necessarily opened at 92. When however the train opens its controller thus cutting off working current the circuit 19 is, of course, closed at 92 and opened at 35 by the track relay 7 releasing its armature as described. Nevertheless if the magnet 90 and its armature were omitted and a wandering current should magnetize the relay 7, as described, said relay attracting its armature 16 and thus closing the circuit 19 at 35 would, as will be seen, magnetize the magnet 36 which, attracting its armature, would open, at 38, the circuit of the solenoid 44, which latter would thus cut off the feeder E from the section m, and, of course, the wandering current, from said relay 7. It is evident, then, that even in this case, any accidental interference with the regular working of the system could only be momentary.

The magnet 90 is put in derived circuit from the conductor 62, and a considerable resistance 93 is included in this derived circuit in order to reduce the current through said magnet to the requisite operative strength. A slight resistance 94 is put in the circuit 62 around said magnet, in order to prevent a dead short circuit of the same.

Similar switch magnets 90, controlling switches as described, are included in the working circuits between the various working sections and the working current feeder E.

Referring now to Fig. 3: This figure illustrates the application of my invention when the alternating current is used for propulsion purposes and to operate the intermediate or auxiliary magnets. One traction rail and the contact conductors are divided into sections or blocks, the relays 6, 7, 8, being under control of direct current from the generator F, all operating as already described. It is not necessary therefore to here further describe this part of the invention.

H represents a high potential alternating current generator from which proceed the leaders 95, 96, to which are connected the primaries of the step down transformers 97, 98, 99, 100 by the wires 101, 102; 103, 104; 105, 106; 107, 108. Each of said transformers has two secondaries. The secondaries 109, 110, 111 of said transformers, respectively, have one leg 112, connected to said traction rail sections 5, c, d, and their opposite legs 114, respectively, connected to the contact or third rail sections Z, m, n, all as shown. Each leg 112 of said secondaries contains a switch as shown at 113, 128, 130, normally closed, while the opposite legs 114 contain switches 115, 129, 131 normally open. These secondaries furnish working or proulsion current to the traveling motors.

ach transformer contains an additional or auxiliary secondary, 116, furnishing current to the intermediate circuits 117, 118, 119, which circuits, respectively, are under control of the relays 6, 7 and 8. Each of these circuits contains two magnets, 121, 122; 123, 124; 125, 126. The secondaries 116 deliver a current much stronger than that operating the relays 6, 7, 8, in order to control the somewhat lengthy throw of the switches included in the heavier circuits of the propulsion current. At the same time this intermediate current is low enough to be controlled directly by said relay magnets, and toavoid all danger from contact with said intermediate circuits.

It will be noted that the intermediate circuits 117 118, 119 are kept normally closed respectively by the normally energized relays 6, 7, 8, by which means the magnets 121,

contact points 135.

122; 123, 124; 125, 126 are kept normally energized. Thus the switches 113 128, 130, in one leg of the respective working current secondaries are kept normally closed, while the switches 115, 129, 131, in the other leg of said secondaries are normally open.

It will be understood that the magnets 121, 122, for instance, control the switches in the working circuits of difi erent sections or blocks.

The operation is as follows: When the car or train 53 enters upon the section or block m, for instance, it short circuits the current from the relay 7, which, releasing its armature 16 opens the circuit 118 at the contacts 35 through the magnets 123, 124. The magnet 123 thus releasing its armature 129 closes the circuit of the secondary 110 at the This, it will be seen, closes circuit between the working secondary 110, and the working section 717., thus furnishing working current to the car or train 53 when its controller is closed, since the switch 128 is already normally closed. The deenergizing of the magnet 124, as described, opens circuit at the contacts 136 in the leg 112 of the secondary 111, thus preventing working current from reaching the section or block (1 as long as said magnet 124 is deenergized, that is, as long as there is a car or train on the block 0. It is evident therefore that a train entering upon said block (1 from the left is instantly deprived of working current and cannot proceed until the train 53 clears the block 6. Nevertheless, the train entering the block d short circuits the current from the relay 8, thus opening the circuit 119 through the magnets 125 and 126. The magnet 125 thus releasing its armature 131 closes circuit at the contacts 137, thus closing circuit between the working or contact section it and the traction rail section (1, and thus closing the motor circuit upon itself of the train entering upon said section or block d. To prevent the motors, when suitably constructed and arranged to be converted into generators, from being thus put in a dead short circuit I introduce the impedance 72 between the contacts at 131 and 136, that is, between the working section a and the traction rail section (1. This impedance may in this case be in the form of a choking coil as shown, or in any suitable form.

It may be here pointed out that the demagnetization of the magnet 126 opens the circuit furnishing working current to the block 6, as already described in connection with the block (1. Thus the train entering upon said block 61, although itself deprived of working current, as described, yet cuts off working current from the block 6, thus protecting itself from rear end collision.

If the train 53 should become stalled, or for any other reason it is desired to bring other trains up from the left or rear, to and including the block 0 the hand switch 138 is closed on the contact 140, thus vitalizing the magnet 124 and cutting out the magnet 123, and the switch 16. This allows the approaching train from the rear to receive working current on the block 0 as well as on the block d. Thus any derangement on the block a need not interfere with the regular operation of trains elsewhere than on that block. Again, if workmen have occasion to work on. the block 0 or its connections the switch 138 may be closed on the contact 141, thus bringing both magnets 124 and 123 into circuit. The latter opens the main working circuit at 135, thus preventing the accession of working current to the contact section m or any part of the block 0.

When it is desired for any reason to prevent the accession of working current to the contact section n, for instance, this may be done by opening the switch 142 in the leg 112 of the secondary 111. Closing said switch upon the contact 143 makes electrical connection between the contact section n and its return d, thus closingthe motor circuit upon itself of any train entering upon the block d. In order, however, to prevent a dead short circuit of the train motors I insert the resistance or impedance 144 between the contact point 143 and the leg 114 of the secondary 11]., thus presenting a resisting or braking force against the approach of such train.

It will be understood that, if preferred, a direct current may be used to vitalize the circuits 117, 118, 119, and their magnets, instead of the alternating current, as illustrated in the corresponding circuits 47, 18 and 19 in Fig. 1, which receive direct current from the feeder G.

Among the advantages of using the alternating current, especially for propulsion purposes, in the manner described, may

be named the following: The range of the working current is confined within the length of a working section or block, which may be a mile more or less in length. It does not have to travel over many miles of feed wire, third rail and return between the power house and location of application; consequently, there can be no appreciable leakage of current. The resistance of the circuit also becomes merely nominal, resulte ing in a very low voltage being required, ap proximately, say, 250 volts, to drive the heaviest train. Furthermore electrolytic action on water and gas pipes is eliminated, and any derangement or loss of current in one block does not necessarily disturb or affect the proper action or use of other sections or blocks. It is also noted that in case of life or for other cause any block may be instantly killed by turning a switch connected with that block without disabling or killing any other block.

It will be understood that magnets adapted for operation by the alternating current are to be used in this system where the use of the alternating current is described, although the specific construction of such magnets is not herein described.

It is evident that my system described may be used in connection with overhead trolley, elevated, surface, slotted roadway, or other systems, and under any conditions where applicable and still be within the spirit, purpose and scope of my invention.

I do not herein claim broadly, in an electric railway system, a sectional working conductor, a working current feeder normally disconnected therefrom, means for connecting the same thereto, or a traction rail divided into sections, said sections constituting returns for the working current, since I describe and claim combinations including these in my co-pending application Serial No. 256,322, filed April 18, 1905.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In an electric railway system embodying a sectional working or contact conductor, a source of working current supply normally disconnected from said working sections, a car or train, means actuated thereby for connecting said current supply to the working sections occupied by said car or train, means under control of said car or train on one sec tion or block for opening circuit in the feed connection furnishing current to a different working section or block, and means for antomatically making direct electrical connection between said last named working section and its return, said electrical connection including a substantial impedance.

2. In an electric railway system having sectional contact or working conductors, a source of working current supply normally disconnected from said working sections, means for automatically connecting said current supply to said respective sections and disconnecting the same therefrom, a car or train, means under controlthereof for automatically preventing the delivery of working current to a working section adjacent to the section or block occupied by said car or train, a second or following car or train provided with a motor circuit, and means 1n cluding an impedance connected with said adjacent section or block for causing the motor circuit of said second car or train to be closed upon itself through said impedance, on the entrance of said train upon said adj acent section or block.

3. In an electric railway system comprising a sectional working or contact conductor, a source of working current supply normally disconnected from said sections, a plurality of automatic switches for connecting said current supply operatively to said respective working sections and disconnecting the same pendent motor-driven car or train, means, in-

therefrom, one of said switches, connected to each block, being normally open, a car or train operating to close the same on entering upon the section or block with which said switch is connected, another switch connected to a different section or block and nor mally closed, said train operating to simultaneously open the latter switch on entering upon said first named section or block, another car or train provided with a motor circuit, and means, including an impedance, for causing said train, on entering upon said difierent block, to close circuit between the working or contact section thereof and its return, said train thus closing its own motor circuit upon itself, through said impedance.

4. I11 an electric railway system, a working or contact conductor formed in sections separated or insulated from one another, a traction rail formed in corresponding sections separated or insulated from one another, a working current feeder normally disconnected from said working sections, but having one terminal arranged for connection thereto, the opposite terminal being normally connected to the respective sections of said traction rail, a car or train, means under control thereof for connecting said working current feeder to said respective working sections on the entrance of said car or train upon said sections, the respective sections of said traction rail comprising returns for the working current feeders connected thereto, means under con trol of said train for preventing the accession of working current to a different working section or block, a second electrically propelled car or train, and means, including an impedance, connected with said last named section or block, for causing said car or train, en entering thereupon, to establish direct electrical connection between the working section of said last named block and its return, and thus to close its own motor circuit upon itself through said impedance.

5. In an electric railway system, a working or contact conductor formed in sections separated or insulated from one another, a traction rail formed in corresponding sections separated or insulated from one another, a working current feeder normally disconnected from said working sections, but having one terminal arranged for connection thereto, the opposite terminals being normally connected to the respective sections of said traction rail, a car or train, means actuated or controlled by an independent current under control of said car or train, for connecting said working current feeder to said respective working sections when said car or train enters thereupon, the respective sections of said traction rail forming returns for the working current connected to the respective working or contact sections, an indeeluding an impedance, for closing circuit, through said impedance, between the work ing or contact section of a different block from that occupied by said first named train, and its traction railreturn, whereby said independent train, on entering upon said different section or block, will be caused to close its own motor circuit upon itself while said first named block is occupied by said first named train.

6. In an electric railway system comprising asectional working or contact conductor, a high voltage alternating current generator, leaders therefrom, transformers having their primaries connected thereto, the secondaries thereof, respectively, having one terminal arranged for connection to the working sections, but normally disconnected therefrom, and the opposite terminal normally connected to the return for the working current, a car or train, means actuated thereby for connecting said secondaries operatively to said working sections upon the entrance of said cargor train thereupon, means under control of a car or train on one block for opening the circuit in the secondary feeder arranged to supply current to a difierent block or section, and means, including an im edance, connected with said last named bloc for closing circuit between the working current section of said block and its return.

7. In an electric railway system embracing a controlling circuit exterior to the movable train circuit, and including a lurality of electro-magnets, a current supp y therefor, and an automatic switch for opening and closing circuit through said magnets, the combination therewith of a hand switch, arranged to cut out said automatic switch, thus removing said magnets from control thereof.

8. In an electric railway system, the combination with a controlling circuit comprising a plurality of electro-magnets, a current supply therefor, and an automatic switch for opening and closing circuit throu h said magnets, of a hand switch arranged to cut out said automatic switch and one of said magnets, thus killing the latter and removing the other magnet from control of said automatic switch.

9. The combination with an electric railway system comprising a sectional working or contact conductor, means for furnishing current thereto, and a return therefor, of

means for automatically closing and opening circuit directly between said working sections and their return, and an im edance included in and forming a part of sai circuit.-

10. The combination With an electric railway system comprising a sectional working or contact conductor, means for furnishing current thereto, and a return therefor, of means including a substantial impedance and a hand switch for closing and opening circuit, through said impedance, between said working sections and their return.

11. The combination, in an electric railway comprising a sectional working or con tact conductor, means for furnishing working current thereto, and a returntherefor, of an impedance, a hand switch arranged to open the main working circuit and to close circuit through said impedance between a section of said working conductor and its return.

12. In an electric railway system, sectional closed rail circuits, an alternating current generator, leaders therefrom, step down transformers connected thereto, their secondaries furnishing working current, a working or contact conductor formed in sections separated or insulated from one another, one of the traction rails formed in cor responding sections separated or insulated from one another, the secondaries of said transformers being normally disconnected from said working or contact sections but having one terminal arranged for connection thereto, the opposite terminals of said secondaries, respectively, being normally connected to the respective sections of said traction rail, means for connecting said secondaries to said respective Working sections when a car or train enters upon said closed circuit sections, the respective sections of the traction rail forming returns for the secondaries of the transformers connected thereto, an impedance, a car or train on one section or block, and means, under control thereof, for preventing the accession of workin current to a different working section or bloc and means for closing circuit through said impedance, between the working section of the latter block and its traction rail return.

WILLIAM ROBINSON. WVitnesses:

SYLVANO E. PARSONS, GEORGE E. MASTERS.

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