US792963A - Railroad-signal. - Google Patents

Description

PATENTED JUNE 20, 1905.

A. M. BULLARD. RAILROAD SIGNAL.

APPLICATION FILED MAY 8, 1903.

3 SHEETS-SHEET l.

f g I fix: 51 1 1:

3 rwemtoz Wifmau PATENTED JUNE 20, 1905.

A. M. BULLARD.

RAILROAD SIGNAL.

APPLIGATION FILED MAY s, 1903.

3 SHEETSSHEET 3.

Q in

Q/Vi messes UNITED STATES Patented June 20, 1905'.

PATENT ()FFICE.

ALBERT M. BULLARD, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR TO AMERICAN SIGNAL COMPANY, A CORPORATlON OF MAINE.

RAILROAD-SIGNAL.

SPECIFICATION forming part of Letters Patent No. 792,963, dated June 20, 1905.

Application filed May s. 1903. Serial No. 156,274.

1'0 00% whom, it may concern:

Be it known that l, ALBERT M. BULLARD, a citizen of the United States, residing at Somerville, Middlesex county, State of Massachusetts,have invented certain new and useful Improvements in Railroad-Signals, of which the following is a specification.

This invention relates to railway-signals, and has for its object to improve and simplify the construction and arrangement of parts and to insure a proper operation of the signals under all conditions; and to these ends the invention consists in the various features of construction and combination of parts arranged and operating in a manner substantially as hereinafter described and producing the results stated.

Referring to the accompanying drawings, Figure 1 is a diagrammatic illustration of a preferred embodimentof my invention. Figs. 2, 3, 4, and 5 are similar diagrams illustrating modifications in the circuits. Figs. 6 and 7 are diagrams showing ways of applying the invention to double and single track railways. Fig. 8 is a vertical section showing a preferred construction of the so-called rheopalm.

The presentinvention is applicable to man-y and various methods or systems of signaling, and especially to those in which a train bridges or short-circuits the rails which are connected to the signaling devices so that they are operated by the passing train, and it is more particularly applicable to what are generally known as cab signaling systems.

The invention will be described and illustrated as applied to a cab signaling system, it being understood that it may be adapted to other systems by those skilled in the art without departing from the general spirit of the invention. So, also, the preferred arrangement of devices and various arrangements of circuits involving somewhat different modes of operation will be described to show the applicability of the broad features of the invention; but it is to be understood that the invention is not limited to the specific details of construction and arrangement set forth, and Where specific terms are used in the specification they are used in an illustrative sense and are intended to embrace all proper equivalents. With this general statement some of the more distinguishing characteristics of the invention will be pointed out and specific illustrations of the use or embodiment of the broad features of the invention will be described.

One of the distinguishing features of the invention is found in the fact that the system of signaling does not operate on margins of current strength or changes in electromotive force or other similar variations of direct current; but the operation of the system and the devices embodied therein depends upon the inherent difference in character between direct currents and fluctuating currents,and the parts are so arranged and combined that the safetysignal cannot be displayed except under the action of a fluctuating current, and the system involves the use of a current-varying or current-fluctuating device. This device is so constructed and arranged that it periodically varies the resistance of an operating-circuit in such a manner as to produce therein a fluctuating current, and the signaling devices included in that circuit are so constructed and arranged that they are operative to produce the safety-signals only when they are properly affected by such fluctuating current, and the failure to produce such a current and to so operate the signals fails to produce a safety signal and displays a danger signal or signals. It may be stated here that by safety or danger signals are included any form of signals, visible or audible or otherwise, and when any particular one is specified it is to be understood as including all proper equivalents. In order to carry out this general mode of operation and to provide means for producing a current-Varying or current-fluctuating device, there is shown what may be properly termed a rheopalm in contradistinction to a rheotome in that it is a device to produce fluctuations rather than actual breaks or interruptions in a stream or current, although it is to be understood that a rheotome may also be used for the operation of this system. This device is connected in the circuit to be controlled and controls the signaling devices,

and in the present instance the rheopalm is connected in the track-circuit and may be properly indicated by the term track device. The designation rheo palm has been adopted by me as a new term particularly appropriate to my invention. It is taken from the Greek noun Waco-Q, a stream, and palmos, a fluctuation or pulsation. This word seems to indicate accurately the effect upon the test ing-current of the operating device thus designated as a rheopalmthat is, a device to change the current from a direct continuous currentto a fluctuating current. The fluctuations may be varied in cl1aracter-that is, the current may be varied in such a manner that the fluctuations or periodic variations are rhythmical and could be expressed by a succession of curves approximating sine waves or the fluctuations or periodic variations may be sudden impulses and could be represented by the square-cornered wave characterizing the abrupt rise from or drop in value to zero, which is commonly known as pulsating current, where the current consists of sudden distinct impulses or rushes of current in contradistinction to an undulatory current. The term fluctuating current as used in the claims herein is intended to embrace all such fluctuations or periodic variations in the direct current as the gradual rising and falling current or the abrupt pulsating current wherein the current may fall to zero. I

The signal-controlling devices which in the present instance are designed to be used in the cab may vary in details of construction and arrangement, but preferably are of an electromagnetic nature and are capable of discriminating between direct currents and fluctuating or pulsating currents, and the signals are connected to be controlled by these signalcontrolling devices, and these devices may be operative or may be rendered inoperative, as the case may be, by the character of the currents supplied to themthat is to say, these devices may be operative under the influence of direct currents and inoperative in response to fluctuating or pulsating currents, or they may be operative to fluctuating or pulsating currents and inoperative to direct currents, the latter being preferable and the one which is described and illustrated herein.

So far it will be seen that the system is one in which varying or pulsating currents are produced under certain conditions and the signals are controlled not by changes in current strength or in electromotive force, but by changes in the character or nature of the current sent to the signal-controlling device, and in this way the disadvantages of depending upon changes in current strength or in electromotive force are avoided. in this system nothing but a fluctuating or pulsating current will hold the signal at safety, and nothing but the rheopalm or current-fluctuating device can operate the signal-controlling devices, and this is so located and arranged that if this device does not properly operate the proper current is not produced and the signals are set at danger. In other words, every other condition than that in which a fluctuating or pulsating current is produced in the circuits will cause the display of a danger-signal, and the safety-signal can only be displayed when the rheopalm or currentvarying device is properly operated, and this can only be operated when all the parts of the system are in operative condition, and any accidental derangement of the systemsuch, forinstance, as might produce a short circuit otherwise than by the car or the opening of the circuit or the accidental introduction of resistance in a circuitwill prevent the operation of the rheopalm and result in the non-operation of the safety-signal devices.

Referring now to the drawings, and more particularly to Fig. 1, the variouscircui'ts are indicated in lines of different character, and in this figure J represents one of the rails of a track, which is shown as a continuous rail or electrically-continuous rail and constitutes what may be termed the re'tu rn-rail, while I represents the insulated rail-sections of the blocks, and M represents the locomotive or car embodying means for sh ort-circui-ting the rails shown as the wheels and axle. H is a third rail or contact device which is connected electrically with'the insulated rail-section at one end thereof and is adapted to be electrically connected to the signal-operating devices on the train by any suitable meansas,

for instance, a shoe F. Connected between the insulated rail-section and the return-rail is the rheopalm or track device D, and while this may be variously constructed it consists in the presentinstance of an electromagnetic device of the so-called iron-clad form, (shown more particularly in Fig. 8,) in which there is a tube D, closed at one end and formingone pole and having a central core D forming the other pole, and this core is shown as being surrounded by a copper tube D and this is surrounded, as shown in Fig. 1, by a number of convolutions of the conductor (Z, bridging the insulated and return rails. The armature D is arranged so as to short-circuit the winding of the rheopalm, and, as indicated in Fig. 1, the armature is in a short circuit d, which is normally open. The operation of this rheopalm may be briefly described at this point, and it will be seen that when for any reason the circuit d is closed the armature D is operated, and this closes the short circuit cl, short-circuiting the winding of the rheopalm, and thus deenergizing the same, and the armature is thereupon released, assuming its normal position and breaking the short circuit d, which will again cause the rheopalm to be energized, again operating the armature to close the short circuit, and these operations are automatically repeated, thereby alternately introducing and removing resistance in and from the circuit, which produces variations in the current traversing the circuit, changing it into a fluctuating current the value of which never drops to zero. The rate of fluctuation may be regulated in a variety of ways, as by the adjustment of the armature with relation to the poles of the rheopalm, adjustment of the contact (Z of the short circuit cl, by varying the thickness and proportions of the iron forming the electromagnet-circuit, by varying the thickness and weight of the armature, by varying the retractive force exerted upon the armature, by varying the number of convolutions of the exciting-coils. In these ways the naturally high periodicity of a rheopalm or rheotome may be reduced. The preferable way of accomplishing this is indicated in Fig. 8, wherein the core D may be said to be surrounded with. a single convolution of thick copper D which forms upon the core a closed secondary winding of extremely low resistance. This has been shown in practice to greatly reduce the rate of fluctuation produced by the rheopalm, as the magnetism in a device so constructed increases and diminishes very slowly, because of the reaction from the induced currents that circulate through the single convolution of copper. The effect of this gradual building up and falling off in magnetism is that the action of the armature is very sluggish, insuring the production of well-defined fluctuating currents. It is evident that, while the preferred construction has been shown, any electromagnetic device which converts direct currents into fluctuating or pulsating currents will render the system operative, and while it is preferable to have a low rate of pulsation when the flashing safety-light or signal is used in the manner hereinafter described it is not necessary to do so.

In Fig. 1,-E represents a source of electromotive force, conveniently referred to as a battery. A, B, and C represent relays, in this particular figure A being a quick-acting relay, B being defined as a sluggish open-circuit relay, and U a sluggish direct-current 'relay. G, Y, R, and W represent signals,

indicated in the present instance as lamps of different colors, and R and Yrepresent audible signals, as bells, although other forms of signals can be used. Relay B is designated an open-circuit relay, because of its function of indicating by the release of its armature the existence of an open circuit in either the cab-circuit or the track-circuit.

What may be termed the cab-circuit includes a battery E, the conductor 6, the slug gish open-circuit relay B, conductor 9, the safety-lamp G, the contact g, the portion f of the shoe, and the conductor 6. This cabcircuit is normally closed, and the safety-signal, as lamp G, is normally illuminated and.

may be termed a normally operative cabcircuit signal. Should this closed circuit be broken, the armature bof the relay B, which is connected to the conductor 7/, is released from its front stop and closes the contact 7/ of the circuit 1 through the visual and audible signals Y Y, (shown in shunt relation to each other,) and these indicate the accidental opening of the cab-circuit and may be termed steady open-circuit signals. For convenience the lamp Y may give a yellow light, the extinguishment of which indicates at once that something is wrong. So, too, under these conditions the safety-lamp G would be extinguished, and this lamp may for convenience give a green light and be an additional warning that there is local cab trouble. Should the battery fail to produce its normal current, the lamp G would be dimmed or extinguished, which would alone indicate trouble, as the signals Y Y might not be operated on the closure of the local circuit g. It is one of the features of the system that some visual signal,

as a lamp, is always displayed so long as the battery is in working condition.

What is properly defined as the testingcircuit includes the battery E, the conductor e, the shoe F, the third rail or conductor H, the conductor a, insulated rail-section I, the conductor (1 of the rheopalm D, the return-rail J, locomotive M, conductor 6 quickacting relay A, conductor a, open-circuit relay B, and conductor 4 to battery. This assumes that the locomotive has arrived at the testing-point and the shoe F has made contact with the third rail H and the local cabcircuit is broken at the contact g.

The direct-current sluggish relay C is included in a local circuit including the battery E, conductor a, conductor 0, lever O, which is weighted or under spring tension, so that it normally rests on the stop 0 and carries a contact 0 adapted to connect with contact a on the armature a, which is connected to the conductor 5.

The danger-signals R and R (shown as visual and audible signals) are in a branch local circuit 0', controlled by the armature c of the relay 0. There is also provided a flashing safety-lamp W, which is in a branch local circuit including the conductor w, which includes a circuit-breaker w, in this instance connected to and insulated from the armature c and operated thereby, and this circuit terminates in a contact 10 and is adapted to make contact with a contact a of the armature a. It may be stated here that the danger-lamp gives a red light when illu minated and the flashing safety-lamp WV gives a white light. The relay C may be of any construction to produce the sluggish effect and is shown as similar to the rheopalm D. This relay may properly be delined as a discriminating-relay in that it discriminates between direct and fluctuating or pulsating currents and is so constructed as-not to be operloo ' A l V ative under the latter currents, but only operative when its coils are traversed by direct continuous currents.

Assuming that the conditions are such as to make a proper test through the testing-circuit and the shoe F has made contact with the third rail H and closed the circuit, the rheopalm D will operate to convert the direct current from the battery E into a fluctuating current, and this fluctuating current will operate :the quick-acting relay A so as to cause its armature a to vibrate in response to the variations produced in its magnetic field. The reciprocating movement of the armature at alternately closes and opens the two sets of contacts (0 20 and a 0 controlling, respectively, the two local circuits. This results in the production and maintenance of a regular flashing in the flashing safety-lamp W, which in itself constitutes asafety-signal- Nothing can produce the regular flashing of this lamp but the track-rheopalm, and unless this operates properly the lamp W will not flash, but it will continue to flash as long as the testingcircuit is closed. The movement of the armature (4 also controls the local circuit, including the discriminating-relay C, and, as before intimated, this is a sluggish relay and of such construction that its armature 0 will not be operated by the pulsating current, but the relay will attract its armature only when energized by a direct steady current, and willrelease its attracted armature should current of any character but a direct current traverse its windings. It will thus be seen that the fluctuating current produced by the rheopalm will not operate the relay C or the dangersignals R R, and if the contacts a 0 are firmly closed and a direct current flows steadily through the relay C its armature is operated, closing the circuit through the danger-signals and at the same time breaking the circuit of the flashing safety-lamp'W. The weighted or biased lever O is so constructed'and arranged that when it is tapped or struck by the armature a in its rapid oscillations it yields promptly to such tapping and greatly lessens the length of time the contacts a and 0 are together, and consequently aids in decreasing the chance that the sluggish relay C will operate. The rapidly-fluctuating currents, which affect the quick-acting relay A and produce the results indicated, practically have no effect on the sluggish relay B, which is normally energized to hold its armature against its front stop, as it is so constructed that so long as sufficient current of any character traverses its windings it will hold the armature b in its normal position. As before stated, the functions of this relay B are to release its armature when too little current flows to effectually operate the rest of the apparatus, including the testing-circuit, and to give notice of the entire cessation of current in the testing-circuit and in the cab-circuit.

It will thus be seen that in this system there are several cab-signals indicating various conditions of the circuit, and they may be summarized as follows: First, there is a steady safety-lamp (green) which is constantly illuminated as long as the electric circuit in the cab is in proper condition and. when the shoe is not in contact with the third rail; second, there is a steady visual and audible signalY Y (yellow) to indicate an open circuit in the track-circuit or the testing-circuit or in the cab-circuit; third, there is a flashing lamp (white) in the local circuit to indicate safety in a positive and assuring manner when the testing-circuit is complete and in operative condition; fourth, there is a steady visual and audible signal R R (red) to indicate danger when the rails are short-circuited, as by a train on the block being tested, which would short-circuit the rheopalm and prevent the conversion of the direct currents into fluctuating currents.

While the general mode of operation of the apparatus is largely apparent from what is stated above, it will appear that when the shoe is not on the third rail, as in testing, the green safety-lamp G is illuminated and assures the continuity of the cab-circuit. When the shoe contacts with the third rail, this green safetylamp is extinguished, and if the block being tested is free and everything is in proper condition the rheopalm will operate and the white flashing safety-lamp W will indicate safety. Should there be danger ahead, as a train in the tested block, the safety-lamp W will cease to flash and the red lamp R and audible signal R will give the danger-signal. This is caused by the short-circuiting of the rheopalm D by the train ahead, thus preventing the rheopalrn from changing the direct into fluctuating current, and the direct current from the battery flows through the closed circuit, producing the results above indicated, and the danger-signal continues in evidence until the tested block is free. Thus as soon, for instance, as a train moves out of the tested block the rheopalm, being no longer short-circuited, operates'to produce the fluctuating current to indicate safety by the regular flashing of the white safety-lamp W. It will be noted further that the danger-signal is practically three fold. in case of danger the white lamp W will not flash, and in practice this lamp is a most conspicuous danger-signal and is preferably placed directly before the engineer, who knows that unless the safetylamp operates to flash in the proper way there is danger ahead. In addition to this failure of the flashing lamp danger is indicated by the red danger-lamp and audible signal. Furthermore, should the testing-circuit be opened or become inoperative the relay B will be deenergized and the yellow danger-lamp Y and audible signal Y will at once indicate that the circuits are not in operative condition. It will further be seen that there is only one condition of safety and that depends entirely upon the circuits being in complete and operative condition and upon the operation of the rheopalm, which acts positively to change the nature of the testing-current from direct to fluctuating current, and no other de- Vice or'combination of devices of the system can do this, and this cannot be done unless all the parts are in operative condition and the tracks are free.

- Having thus described the principle of operation of the system whereby the cab-signals are operated and controlled by characteristic changes in the nature of the current used for testing, which changes are effected by a device located at the distant end of the tested block and operative only under safe conditions in all respects, it is obvious that many variations in the means of the practical application of this principle are possible and some are briefly indicated in the drawings.

In Fig. 2 a modification of the cab-circuits is shown in which the sluggish relay C is introduced into a series relation with the main testing-circuit and is therefore directly subjected to the pulsations of the testing-circuit. The quick-acting relay A performs but one functiom-that is, flashing the safety-lamp W. The back contact of the armature 0 of the relay C is included in the local circuit through the lamp W and will cause the latter to be extinguished when the armature is attracted in response to direct currents under danger conditions.

In the circuits indicated in Fig. 3 a saving in apparatus is effected by the combinations of the functions of the relays A and B into one relay AB, and the circuits are so arranged that the front contact of the armature (6 controls the flashing lamp W and the back contact of the relay controls the open-circuit signals Y Y. The combined relay AB in this case is quick-acting. To aid in insuring a back contact of high resistance during safety oscillations of the armature a, and hence the non-operation of the signals Y Y, a yielding contact-lever O is preferably added, as shown, the operations of which will be understood. The sluggish relay C when operated by direct currents actuates the danger-signals B R by its front contact and extinguishes the safety flashing signal W by breaking the circuit of said lamp at its back contact. In this arrangement when the shoe is off the third rail the relay AB draws up and holds its armature as long as the shoe-lever is in contact with the contact-point g of the cab-circuit g; but when the shoe is on the rail this contact is broken and contact is closed at g through the safety-signal W.

In Fig. 1 another variation is shown wherein the flashing safety-signal IV is placed directly in series with the testing-circuit and is operated by the pulsations of the testing-circuit during safety conditions. When danger or short-circuit conditions exist, the sluggish relay C, which is also directly in the testingcircuit, attracts its armature c and operates the danger-signals R R by closing the circuit at its front contact and the circuit-breaker w short-circuits and suppresses the safety-signal W.

In Fig. 5 the circuits are very similar to Fig. 1, except that a spring-recovered lever O has been added to the open-circuit relay B. Normally currents from battery E do not 'sufliciently energize the relay B to cause its armature to overcome the retractile force of the bias lever 0 but when an abnormal current flows through the relay B the armature b presses the bias lever 0 into its back contact and actuates a signal Z in the branch circuit e. The movement of the lever suppresses the safety-signal W and the ordinary danger-signals R R, the circuits of the relay C and of safety-signal WV being broken at the front contact of the lever 0 In Figs. 6 and 7 is illustrated diagrammatically the use of the invention applied to double and single track roads, some of the circuits being omitted for clearness and enough being shown to indicate the general arrangement and operation of the devices. In Fig. 6the inward and outward tracks comprise one complete block 2 and 5, the beginning of a block 3 and 6, and end of a block 1 and 4, and at each engine M M M are shown a battery and a discriminating-relay G, and the various circuits of the rheopalms and other parts of the system are clearly indicated and need no extended description, it being suflicient to say that the signals in engine, M in dicate danger, while those of engines M M indicate safety.

In Fig. 7 is illustrated one application of the invention to a single-track railway where the arrangement is somewhat complicated in order to protect trains moving in opposite directions and where it is necessary that a rheopalm should be connected across each end of a block and some means must be provided whereby the rheopalm at the end near where the test is made shall not be operated to affect signals on the engine at or nearthat end. Various ways of accomplishing this can be utilized and, without limiting the invention in any respect, one way is indicated in the drawings, which consists in polarizing the rheopalms, as by permanent magnets P, so that the rheopalms will respond only to currents in the proper direction. .As indicated, there is a regular alternation from block to block of the polarity of the rheopalms, of the arrangements of the insulated rail-joints, and of the connections of the third rail to the rail end adjoining said joints, as clearly indicated.

While it is unnecessary to describe in detail all the circuits indicated, as they will be understood by those skilled in the art by what has already been described, we may consider the circuits in relation to the engines M and M where the latter is in the block that the former is testing, and therefore causes a danger-signal to be displayed in the cab of the latter, because the wheels of engine M are short-circuiting both the distant rheopalm D and the near polarized rheopalm D, included in the branch of the testing-circuit. The rheopalm D is short-circuited by the wheels of the engine M. The testing-circuit may be traced from the positive terminal of the battery E to the shoe F and third rail H, thence to rail I, through the short-circuiting wheels of engine M, back over rail J ,Wl16lS of engine M, discriminating device C to battery. As no operative current-varying rheopalm is included in either branch of this testing-circuit, the discriminating-relay C displays a danger signal. This changes to safety when engine M moves out of the block 3, when the polarized rheopalm D being no longer short-circuited by the wheels of engine M and being operative to positive current, will produce pulsating current in the testing-circuit, which causes the discriminating device 0 to set the signals to safety. The near rheopalm D, being negatively p0- larized, will not respond to the positive current now energizing it in a branch circuit. Thus in neither condition will the near rheopalm D operate. Rheopalm I) does not shunt back to the battery E enough direct cu rrent to interfere with the proper operation of the discriminating device nor does even very heavy leakage from rail to rail do so as long as such leakage does not become, in effect. so heavy as to constitute a short circuit. Engines M and M are shown as simultaneously testing the same block (N o. 2) from opposite directions,and this is indicated in both engines by the display of the special signals Z Z, which are dependent for their operation upon the series connection of the batteries of both engines with the resultant increase of voltage and cu rrent. The path of this abnormal current is from the positive side of the battery E of engine'M, the shoe F, the rail 1 Wheels of engine M through and operating the special signal Z (which is so adjusted as not to be operated by normal current,) the discriminating device G (which is rendered temporarily functionless by the operation of signal Z the negativeterminal of battery E positive terminal, the shoe F the rail 1' to the wheels of engine M, through and operating the special signal Z and through the now functionless discriminating device C back to the negative terminal of battery E. In addition to this circuit there are subsidiary or branch circuits emanating from each battery and including the near and distant rheopalms from each direction; but the resistance of the abovetraced circuit over which current passes at the doubled voltage is so much lower than said I subsidiary circuits that the testing-rheopalms are not operated, It is therefore merely as an added precaution that the special signals Z and Z are made to completely suppress the safety-signal functions of the discriminatingrelays C and C One way of doing this is illustrated in diagram Fig. 5, above referred to, wherein relay B cooperates with signal Z to attain the desired result; but other equivalent ways may be used.

Having thus specifically described the preferred embodiment of the invention and illustrated various applications of the same, it will be understood that the invention is not limited to the details set forth, as other arrangements, constructions, and connections can be made which will embody the principles of the invention, and these can be varied to adapt the invention to various uses under various conditions.

I claim 1. In asignaling apparatus, adirect continuous-current circuit, means for changing said direct continuous current to fluctuating current, and signal devices distinct from said changing means operated by said changed current, substantially as described.

2. In asignaling apparatus, adirect continuous-current circuit, means for changing said direct continuous current to fluctuating current, signal devices operated by said direct continuous current, and other signal devices operated by said changed current, substantially as described.

3. In asignaling apparatus, adirect continuous-current circuit, means for changing said direct continuous current to fluctuating current, means for discriminating between direct and fluctuating current, and signal devices operated by said changed current, substantially as described.

4. Inasignalingapparatus, adirect continuous-current circuit, means for changing said direct continuous current to fluctuating current, means for discriminating between direct and fluctuating current, signal devices operated by said direct continuous current, and other signal devices operated by said changed current, substantially as described.

5. In a signaling apparatus, the combination with the track, and a direct continuouscurrent circuit adapted to be connected therewith, of means connected With the track for changing said direct continuous current to fluctuating current, and signal devices distinct from said changing means operated by said changed current, substantially as described.

6. In a signaling apparatus, the combination with the track, and a direct continuouscurrent circuit adapted to be connected therewith, of means connected with the track for changing said direct continuous current to fluctuating current, means for discriminating between direct and fluctuating current, signal devices operated by'changed' current, and

other signal devices operated by direct continuous current, substantially as described.

7. In a signaling'apparatus, the combina- ""tion with the track, and a direct continuousing means operated by said changed current,

substantially as described.

8. In a'signaling apparatus, the combination with the track, and a direct continuouscurrent circuit connected therewith, of means for changing said direct continuous current to fluctuating current, means for discriminating between direct and fluctuating current, a flashing signal device operated by said changed current, and other signal devices operated by direct current, substantially as described.

9. In a railway-signal, the combination With the track, and circuits adapted to be connected therewith, of a safety-signal operated by fluctuating current, a danger-signal operated by direct continuous current, means for controlling the circuits including said signals, and means for changing direct to fluctuating current, substantially as described.

10. In a railway-signal system, the combi-' nation With a track section or block, of circuits adapted to be connected to the track, a safety-signal operated by fluctuating current, a danger-signal operated bydirect continuous current, means for controlling the circuits including said signals, means for connecting said circuits to the block at or near one end thereof, and means located at the distant end of the block for changing direct current to fluctuating current, substantially as described.

11. In a railway-signal, the combination with a track-section, and a direct continuous- -current circuit, of means for connecting said circuit to the track-section for testing the circuit, means located at or near one end of said track-section for changing said direct current to fluctuating current, and a safety-signal device operated by said changed current, substantially as described;

12. In a railway-signal, the combination With a track-section, of signal-circuits, means for connecting said signal-circuits to the tracksection, signals controlled by said circuits, said signals respectively being controlled by direct current and by fluctuating current, means connected with said circuits for discriminating between direct and fluctuating current and for controlling the circuits including said signals, and means connecting with the track-section for changing direct current to fluctuating current, substantially as described.

13. In a railway-signal, a cab-circuit including a source of direct continuous electric current, a track-section, and connections between the cab-circuit and'traclt-section, a normally operative safety-signal in said cab-circuit, a normally open cab-signal circuit, a safety linecircuit signal, a danger line-circuit signal, and means for rendering said safety line-circuit signal inoperative When said danger-signal is operated, substantially as described.

14. In a railway-signal, a cab-circuitincluding a source of electric energy, a track-section, means for connecting said circuit to said tracksection, a safety-signal operated by fluctuati ng current, a danger-signal operated by direct continuous current, means connected to said cab-circuit for discriminating between direct and fluctuating current, and means connected to the track-section for changing direct current to fluctuating current, substantially as described.

15. In a railway-signal, the combination with a track-section,-of a cab-circuit including a source of electric energy, a normally operative safety-signal, a normally open cab-circuit signal, a track danger-signal and a track safety-signal, and means for connecting said circuit to the track-section, substantially as described.

16. In a railway-signal, the combination With a track-section, of a cab-circuit including a source of electric energy, a normally operative cab-circuit signal, a steady open circuitsignal, a steady danger signal, a flashing safety-signal and circuits including electromagnetic'devices for controlling said signals, and means for connecting said cab-circuit to the track-section, substantially as described.

17. In a railway-signal, the combination With a track-section, of means for changing direct current to fluctuating current, a signaling-circuit adapted to be connected to said track-section, a safety-signal operated by fluctuating current, a danger-signal operated by direct continuous current, a relay in said circuit controlling normally open local circuits including said danger and safety signals, and means for closing said safety and danger circuits depending upon the character of the current supplied to the same, substantially as described.

18. In a railway-signal, the combination With atrack-section, of a signal-circuit including safety and danger signals operated, respectively by fluctuating or pulsating current and direct continuous current, and means connected to the track-section for changing direct into fluctuating or pulsating current, said means comprising an electromagnetic device the coils of Which are connected in the circuit, the core being surrounded With a closed secondary Winding and the armature of Which is connected in the circuit and arranged to shortcircuit the coils, substantially as described.

19. The combination of electrically-controllable railway-traflic-controlling apparatus differentially responsive to different current characteristics and means for supplying elec- IIO ing a number of current characteristics including a periodic variation, such means for supplying electricity being governable by movement of a railway-vehicle along the railwayline and being in controlling relation to the traffic-controlling apparatus through suitable conductive means including a conductor common to the different current characteristics.

21. Thecombination of'electrically-controllable railway signal-indicating apparatus differentially responsive to different current characteristics and means for supplying electricity having a number of current characteristics including a periodic variation, the signal-indicating apparatus being in controllable relation to the means for supplying electricity through suitable current-transmitting means including a conductor common to the different current characteristics.

22. The combination of electrically-controllable railway signal-indicating apparatus differentially responsive to ditferent current characteristics, and means for supplying electricity having a number of current characteristics including a periodic variation, such means for supplying electricity being governable by movement of a railway-vehicle along the railway-line and being in controlling relation to the signal indicating apparatus through suit-able current-transmitting means including a conductor common to the dilferent current characteristics.

23. Electrically controllable railway-traffic-controlling apparatus selectively responsive to a current characteristic consisting in a periodic variation to perform one operation and also controllable by electric current to perform another operation, and means for producing the current of periodic characteristic and the current for efiecting the second operation of the trailic cont-rolling apparatus, such apparatus being controllable by the current-producing means through suitable current-transmitting means including a conductor common to the current of periodic characteristic and the current for effecting the second operation.

24. The combination of electrically-controllable railway-traflic-controlling apparatus, a rail-circuit in controlling relation to the traftic-controlling apparatus, and means for sup plying to the controlling rail-circuit electricity having a number of current characteristics including a periodic variation, the traflic-controlling apparatus being differentially responsive to each of such current characteristics.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

ALBERT M. BULLARD;

Witn esses:

SUMNER RoBINsoN, FREDERIC L. HULL.

Images