US1086752A - Block-signal system. - Google Patents

Description

J. BURKE.

BLOCK SIGNAL SYSTEM.

APPLIOATIONIILED JUNE 28, 1911.

1,086,752, Patented Feb. 10, 191i 3 SHEETS-SHEET 1.

J. BURKE.

BLOC-K SIGNAL SYSTEM.

APPLICATION FILED JUNE 28, 1911.

Patented Feb. 10, 1914.

J. BURKE.

BLOCK SIGNAL SYSTEM.

APPLICATION FILED JUNE 28, 1911.

1,086,752, Patented Feb. 10, 1914.

3 SHEETS-SHEET 3. Q

Fig: '7,

WIT/258858 q; Q U q; INVENTOR M Br ATTORNEYS the above character by means of simple, iPl-- being caused by current being turned on by "UNITED STATES @ENT OFFICE.

JAMES BURKE, OF ERIE, PENNSYLVANIA, ASSIGNOB, TO GENERAL RAILWAY SIGNAL COMPANY, A CORPORATION OF NEW YORK.

BLOCK-SIGNAL SYSTEM.

To all whom it may concern:

Be it known that I, J AMES BURKE, a citizen of the United States, residing at Erie, in the county of Erie and State of Pennsylvania, have invented certain new and useful Improvements in Block-Signal Systems, of which the following is a full, clear, and exact specification.

This invention relates to block signal systems in which the propulsion current is alternating in character and in which the signal current is also alternating, but is made of different frequency from that of the propulsion current.

The present invention relates particularly to such relationship of the relay motor to the block sections and the introduction of and proper relationship of means for affecting the phase of the currents supplied to the relay motor so as to be properly responsive to its signal current and unresponsive or immune to the propulsion current so as to secure proper operation and prevent improper operation of the signals.

The object of my invention is to insure the proper operation of signals in a system of expensive apparatus, and which avoids com plexity in the relationship and connections of the various devices.

In some systems of operating railway signals, it is customary to have the signal arm brought to a clear position by an electric signal motor. the operation of said motor means of a relay, operated by a relay motor. The railway is divided into segregated blocks. Across the two rails, forming a block of the, railway, is connected a. single phase relay supply, generally at one end of the block, and across the same rails, generally at the other end of the bloclgisconnected the relay motor, which by rotation in say a clockwise direction, will close the contacts of the relay by the operation of the motor relay against gravity, thereby turning the actuating signal current upon the signal motor, and thus bringing the signal arm into 1 a position indicating clear. Now when a train enters the block the two rails are joined together by the wheels and axle and the relay supply short-circuited, bringing Specification of Letters Patent.

Application filed June 28, 1911.

Patented Feb. 10,1914.

Serial No. 635,885.

the supply of the signal motor and letting the signal drop to the danger position. After the train leaves the block the relay supply again resumes normal voltage between the rails, actuating the relay motor and closing the signal motor supply ci :uit, when the signal motor again brings th signal to clear position.

It can readily happen that a small part of the propulsion current going through the rails gets into the relay motor, and can by actuating the same, hold the clear when there is a train in the blocl; and the relay supply short circuited. Such a condition might cause disastrous accidents. If however, the relay motoris-immune to the propulsion current of, say cycle, and a frequency is adopted for the relay supply on the rails which willoperate the relay motor, for example cycle, then no false signal can be caused by the propulsion current getting into the relay motor. Again, if it is desiredto have the relay close some other contact to operate some other signal, for example, this can be accomplished by substituting instead of the cycle relay supply, a supply that would operate the relay motor in the opposite direction, for example, 10 cycle.

The system can be readily understood from the accompanying drawings.

Figure 1 is a (.liagrannnatic arrangement showing one block of a railway, the relay motor, the signal motor and signal arm, and the accompanying circuits. Fig. 2 shows a diagrammatic arrangement of the relay motor together with auxiliary resistances and reactant-es which are preferably contained within tht= motor casing, and are so assumed in the illustration of the relay motor in Fig. 1; Figs. 3, 4 and 5 illustrate the relative phase values resulting in the operation of the device with various frcqucncics, as will he better understood in connection with the descriplionof each of these figures; Fig. (3 is a modification.of the arrangement of circuits for the operation of the relay motor; Figs. 7 and 8 show rail ay signal systems embodying my invention; and Fig. 5 is a detailed view illustrating independent magnctic circuit-s for reactances.

llcfcrring to Fig. 1, the two rails forming a block are indicated as 1, which may be the current in the relay motor to practically connected to adjacent blocks by well known zero and permitting the relay contact to drop back to an. open position, interrupting formsof inductive bonds, for the purpose of maintaining the electrical continuity of the rails for the propulsion current, and

without material opposition to the flow of the propulsion current, while separating the blocks for signal purposes, as indicated at 2, showing diagrammatically the inductive bonds at each end of the block. The source of the propulsion current is indicated at A as a single phase source supplying current to a trolley wire or third rail B. The power current passes from the trolley line or third rail through the circuits of the propelling motor or motors through the car wheels and returns to t e source A through the rails. The conductors 3 carry the single phase supply from the source C for operating the relay motors, at a voltage suitable for transmission of the energy, and this is stepped down by means of transformer indicated at 4 to a relatively low voltage for connecting across the rails of the block 1, and in series with the supply to the rails is the limiting resistance indicated at 5, for

the purpose of limiting the current when the two rails are short circuited by a train in the block. Across the rails at the other end of the block, is connected the selective relay motor, indicated at 6, which shows a motor case containing the relay motor and auxiliary apparatus associated with its operation, and which is shown in detail In the diagram Fig. 2, and all of which is included between the connecting wires 7 and 8. On the relay motor is shown pinion 9 geared to gear 10, which gear carries contactors l1 and 12 at the end of an arm 13, which is Weighted to bring it to neutral position as shown. If motor is rotated clockwise, the arm 13 will move toward the contacts 14 and 15 until contactor 11 joins the contacts 14 and 15, thus completing circuit for operating the si nal motor 16, which in this instance is s own operated from the signal supply wires 3, and which by means of pinion 17 and gear 18 operates the semaphore or signal arm 19, bringing it into clear position as shown by the dotted line indication of the arm. The contacts 2Q and '21 are for the purpose of clos ing the circuit by the operation of the relay motor, in the reverse direction, and may be in the operating circuit of another signal, or some other device.

The operation is as follows: Assuming the propulsion supply as 25 cycles and a signal supply of 60 cycles. When the signal supply is first applied on conductors 3, if no train is in the block 1, the 60 cycle current from transformer 4 passes over the rails into the relay motor system 6, by conductors 7 and 8, and the motor starts revolving in a clockwise direction, and by means of pinion 9 and gear 10, moves the arm 13 away from its gravity position toward the contacts 14 and 15, bridging them by contactor 11, which closes the signal 7 relay motor motor circuit from supply 3 through signal motor 16, operating said motor, and by means of pinion 17 and gear 18 brings the semaphore arm 19 from horizontal position up to clear position, as shown by the dotted line at 19. Now if a train enters the block 1, as is indicated by the two wheels and axles 22, the said wheels and axles short circuit the relay supply, bringing the current in the relay motor nearly to zero, and the arm 13 falls away by gravity to'its gravity position, opening the signal motor circuit at 14- and 15, then the semaphore arm 19 drops to its horizontal position by gravity to the position shown in full lines, where it rests on a stop, thus showing dai'iger. \Vheu the train leaves the block the operation of the signal is repeated as first described, bringing the semaphore arm to clear position, Now if the relay motor 6 would also operate on the 25 cycle propulsion current,as has been the case with motors heretofore available, and some of this propulsion current would get into the relay motor 6, it-would operate the relay motor and show the semaphore clear when a train would be in the block, or if the 60 cycle supply'currcnt was holding the signal clear and some 25 cycle propulsion current was also passing through, then the cutting oil of the G0 cycle supply, by a train entering the block, would not release the signal and bring it to danger, as the cycle pro pulsion current would continue to hold it clear. But by the use of a motor selective as to frequency and immune to the 25 cycle propulsion current, used for this illustratlon, the 25 cycle propulsion.current becomes harmless to the signaling. and the operation of the signal system is as safe as if no 25 cycle current was getting mixed up with the system.

If the relay motor should be supplied with current from a circuit of lower t'requency than that of the propulsion current.

that is, if supplied with say ten cycles. the will then operate in the OPPO- site direction and bring arm 13 toward contacts Q0 and 21, closing said contacts by contactor 12, the closing of which contacts may be utilized if desired for the operation of another device, as will be more fully under stood from the following dcscriptioi'i.

The relay motor (3 may be arranged so that instead of being immune to the 25 cycle propulsion current, it will operate under it, but in the reverse direction from that which the GO cycle signal supply will operate it, should the conditions require it.

The application to a signal system is but one use of the selective motor. I wish it understood, however, that it may be used for any service Where selective operation by definite frequencies is desired.

Fig. 2 shows one arrangement of the selective motor and associated circuits as contained between the wires 7 and 8 of Fig. 1. Referring to Fig. 2, 7 and 8 are the same Wires as shown in Fig. 1, bringing the supply to the relay motor and associated circuit contained within. The rotor of the motor is indicated by 23 and the windings of the motor are indicated at 24 and 25, in this instance being two separate windings illustrated as being placed 90 degrees apart, as in an ordinary 2 phase induction motor, one of the phase windings being indicated at 24 and the other at 25, these twowindings cooperating to operate the rotor of the induction. motor, which rotor is indicated at 23. The two windings of the motor, 24 and 25, if supplied with alternating current with phase displacement between the current in the two windings, will produce a rotating field, thus causing the rotor.23 to operate. Winding 24 is supplied direct from the supply 7 and 8 from the rails; winding 25 is supplied through reactances 26 and 27 and resistances 28 and 29, each preferably adjust-able in any suitable manner, resistance 28 and reactance 26 being connected in series between the supply lines 7 and 8, and

. reactance 27 and resistance 29 being con nected in series between the same supply wires 7 and 8. Winding 25 is connected from the junction of reslstance 28 and reactance 26, indicated at 30 to the junction of reactance 27 and resistance 29, indicated at 31. In series with winding 25 is resistance 32, as shown, preferably adjustable.

The function of the reactances 26 and 27 and the resistances 28, 29 and 32, is to regulatethe phase displacement of winding 25 in reference to winding 24 of the motor.

It will be seen that the reactances 26 and 27 have one magnetic circuit between them,- as thefiuxes are in series and in phase with each other, and the single magnetic circuit can therefore be used, but independent magnetic circuits could of course, also be used, as indicated in Fig. 9.

The action of regulating the phase will be best understood by the diagram Fig. 3.

Referring to Fig. 3, 7 and 8 represent the supply wires as used in Fig. 1 and Fig. 2, which supply the motor winding 24 direct, as shown in Fig. 2, and for reference is assumed to'have a phase value of 0,.as represented by the horizontal dotted line 7 and S. The resistance 28 in series with the reactance 26, and the reactance 27 in series with re' equa *to the resistances 28 and'29. Then a potential will be established between the junction points 30 and 310i phase value, as represented by the dotted line 30, 31, which it will be seen is displaced by a certain angle from the horizontal line 7 and 8, and which in Fig. 3, isapproximately 90 degrees as indicated at 33 in the diagram. Under this condition, with phase winding 24 of the motor connected across 7 and 8, and with Winding 25 across 30 and 31, eliminating modifying influences, the relay motor would have its phases supplied with approximately 9Q degrees phase displacement, but may be modified by resistance 32 of Fig. 2, as will be explained later. Now if the frequency of the supply between 7 and 8 is changed to say 25 cycle, which we have assumed as the propulsion frequency, the resistances 28, 2 9 and 32 remain unchanged, because they are independent of the frequency, but the reactances 26 and 27 are reduced approximately in proportion to the haqmac and the diagram therefore becomes for 25 cycle, as illustrated in Fig. 4. By referring to Fig. 4, it will be seen that the angle 33 is no longer 90 degrees as is the case in Fig. 3, but has become approximately 45 degrees, and the relay motor would, under this condition, have winding 25 lagging 45 degrees behind the phase of winding 24, unless modified by the resistance 32, shown in Fig. The function of the resistance 32 is to modify the phase relations between phases 24 and 25 of the motor. It is known that the phases 24 and 25 have some inherent resistance and reactance, but if the two windings are alike, there would be no phase displacement between them it connected across the same supply mains, and consequently no rotation of the motor. If resistance is added to one phase, say 25, by putting re sistance shown at 32 in Fig. 2 in series with it, then phase 24 would lag behind phase 25, and phase 25 would therefore lead in advance of 24.

Considering the 25 cycle condition when such a resistance for 32 is chosen as to make an angle of advance equal to the angle of lag produced by the reactances 26 and 27, and resistances 28 and 29 as shown in Fig. 4, and the winding 25 is connected with the resist-- ance 32 in series with it across the points 30 and 31 of Fig. 4, as shown in Fig. 2, then the angle of advance cancels the angle of lag, and the two windings 24 and 25 have no phase difference between them and there is no rotation of the relay motor. Thus, if resistance 32 is chosen to make a lead of 45 d mately 45 d rees, makings net lag in the I phase of 25 o the motor, equal to 90 degrees have the following tabulation .as shown in diagram Fig. 5, making a reminus 45 degrees, equals 45 degrees, and the relay motor will operate in the predetermined direction say, clockwise. In practice it will generally occur that the change in frequency will modify the phase lead due to resistance 32, so that the exact figure given above for the net lag of 45 degrees, Will be modified in an'sount depending upon the characteristics of the relay motor, but the principle remains the same.

If we now apply'say, 10 cycles, to the signal circuit, the diagram of phase relation changes on account of the change in reactance for this frequency, and becomes for example, as shown in Fig. 5, in which it will be seen that the angle indicated as 33 has become very much less and is approximately 19 degrees. Under this condition We have approximately degrees lead, in phase 25 due to-the resistance and 19 degrees lag sultant of minus 19, equals 26 degrees lead of phase 25 relatively to phase 24. Thus this means that the relay motor willnow run in the opposite direction for at 60 cycle, 25 had a lag, but now at 10 cycles it has a lead, in reference to the winding 24.

Comparing the three diagrams Figs. 3, 4 and 5, and assuming a resistance 32, producmg a lead in winding 25 of 45 degrees, we

The actual amoirnt maybe modified from the exact figures given, depending upon the characteristics of the relay motor, but as the table illustrates, at the assumed 25 cycle condition of Fig. l, the relay motor immune or has no phase difference, while at the 60 cycle condition of Fig. 3, has a phase dif fcrcuce in one direction, or positive. and still at the condition. of .0 cycles as in Fig. 5, it ias a phase difference in the opposite direction, or negative, thus causing one direction of rotation at 60 cycle and another direction of rotation at 10 cycle.

It will be readily understood that the proportions of reactanccs, resistances, angles of lag. etc, should be chosen to best suit the re- (piiremcnts, hut in all cases the invention utilizes the changein angle of lag, due to the variation in the Value of the rcactances with the frequency.

The resistance 32 instead of being separate may he inherent in the motor by winding phase 25 with higher resistance wire.

The reactance 26, 27 and resistance 28, 29 and 32, may all be contained in the motel case, only two wires coining out'of the motor case, as shown in Fig. 1.

Various modifications may be made, for example, referring to Fig. 6, 7 and 8 are supply wires as before. 24 is one winding of the motor as before, but with its middle point connected to one end of winding 25 of the motor, and winding 25 preferably having half the turns of winding 2-1. 32 is the modifying resistance as before, in series with phase winding 25, and 26 a reactance, in series with 28 a resistance. This arrangement eliminates one of the resistances and one of the reactances, by interconnecting the windings of the motor, but the phase displacement and other actions are practically the same as in the previous illustrations.

In the description of windings of the motor 24 and 25, we assumed them displaced 90 degrees, but other displacements may be more suitable for certain cases.

Referring to Fig. 6, the halves of winding 24, one from 7 to the junction of 25, and one from the junction of 25 to 8, may be displaced in phase, or a 3 phase winding may be suitable in certain cases in which one phase is from 7 to the junction point of phase 25, and the other hase from the junction point to 8, or in ot ier words; phase Ql of diagram (3, really represents in this case two phases of a three phase motor, and winding 25 represents the third phase of a 3 phase motor.

Fig. 7 illustrates diagrammatically an embodiment of my invention in which signaling currents of different frequencies are used with advantageous results. The figure represents a system in which the rails are continuous electrically with no insulation in the rails bet ween l)lO('l sections Four block sections are illustrated divided by cross- Jonds 54- of sutiieiently low resistance to avoid any appreciable obstruction to the passage of the propulsion current between rails. The parts similarly lettered and numbered represent corresymmlingly designated parts already described. The source A supplying th! propulsion current is assumed to ha \e a frequency of 23 cycles as before. The source (l for controlling the operation of one set of signals may be assumed to have a frequency of (30 cycles as before. This source is shown as supplying current to each alternate block section through step-down transformers 4. In this instance the signaling current is shown supplied to approximately the middle of the alternate block sections instead of at the end. of the blocks. Another source of signaling current is indicated at D, which supplies current to wires extending along the line of the road similarly to the wires from the source C. The frequency of the source D is difiercnt from that of the source C or that of the propulsion current and may be assumed, for example, to be 10 cycles. This source suppliescurrent through the step-down transformers to approximately the middle of alternate block sections not su )plied by the source C as shown. At the left-hand end of the first block section is shown a relay motor 6 of the character already described adapted to respond to the cycle current derived from the source C and for controlling, as already described, the signal arm 19 for signaling trains passing to the right along the track. At the other end of the first block is illustrated a similar relay motor 6 and signal controlled thereby for signaling trains passing along the track in the opposite direction. The relay motors and controlled signals of this block, while adapted to respond to the 60 cycle frequency of the source C, are not affected by the 25 cycle propulsion current as already described, nor can sufficient current of the 10 cycle signaling current in the next block reach these relay motors to affect the operation of the signal motors in the first block. The only effect of such slight current which might pass to the first block would be to tend to turn the relay motor in the opposite direction, as already described, but this tendency would tiff insufficient to affect the motor. Thus tl'ie relay motors 6 could not be affected by the signaling current derived from the source D to close the circuits of the signal motors. The above-statements with reference to the first block are also true with respect to the third block and would be true of the fifth, seventh, ninth and other alternate hblocks along the road supplied by the the signaling similar torthat of the first and third blocks, with the exception that the relay motors source C.

' Referring now to the second, fourth and other alternate block sections supplied by v source D, the arrangement is are adapted to respond to the 10 cycle frequency of the source D and rotate the relay motors in such direction as to close the circuits of the signal motors, placing the signals in the safety position when. no-trains are in such blocks. These relay motors 35 are unaffected by the frequency of the propulsion current and the only effect of the 60 cycle current from the source 0 if some such slight current reached the relay motors 35 would be to tend to rotate such motors in a direction away from the contacts of the sigrial motors of the second, fourth, etc. blocks, but such current would be insuflicient to affeet the proper movement of the relay mo tors 35.

In order to secure the proper operation of the system of Fig. 7, the bonds 34 must be such as to give no objectionable opposition to passage of the propulsion current, but give suflicient opposition to the flow of the signaling currents so that when no trains are in the blocks the current passing through the relay motors 6 and 35 derived from their respective sources,

cause such motors to operate and place the.

signals in the safety posit-ion. other words, the resistance or impedance of the relay motors (3 and 35 with relation to the resistance or impedance of the rail circuits of the signaling currents through the bonds 34 must be sufficiently low in accordance with well-understood principles that the motor relays will be operated to cause the signals to be held in the safety position when no trains are in the respective blocks. It will also be understood that in this system any of the signaling current of one block section cannot interfere with the proper operation of the signals in other block sections, because the signaling current which might pass from one section into ad joining sections will be so slight as to have no controlling effecton the relay motors of adjoining sections. When a train is in any one block section, the car wheels and axles form such a direct path between the rails for the signaling current that the relay motors of that section are robbed of the signaling current, causing the circuits of the sig nal motors to be opened and thereby placing the signals controlled from the block section in question to be placed in the danger position.

It will be understood that various relative frequencies may be selected for the different signaling currents and for the propulsion current, provided that the relay motors are not operated by the passage of the propulsion current and that the relay motors of alternate block sections are not sufficiently responsive to the signaling current of differ ent frequencies of intervening block sections so as to be controlled by the slight current in any one block section which might happen to pass from adjoining block sections.

It will also be understood that in some instances the bonds 34 may be eliminated entirely and still obtain satisfactory operation of the system owing to the fact that the signaling current of any one block sec tion will find a path through its respective relay motors or through the car wheels when a train is in the block and sufficient signaling current cannot pass to adjoining block sections to influence the motor relays of ad joining block sections.

Fig. 8 illustrates another embodiment of my invention somewhat similar to that described with reference to Fig. 7. In the case of Fig. 8, however, the bonds 30 form a direct connection between the rails of resistance as low as desired and the rails and bonds 36 of any one block form a primary At the ends of each block C and D, will i train is in the block, induces sufficient electromotive force in the secondaries 37 to operate the relay motors 6 or 35 to close the circuit of the signal motors and hold the signals in the safety position. When the train enters a block, the car wheels and axles form a low path for the signaling current of that block, so that no appreciable electromotive force is induced in the secondaries 37 or of sufficient amount to operate the relay motors of that block.

It will also be understood that the signaling current of successive block sections bein of different frequencies, no controlling e ect upon the relay motors of one block occurs by reason of the passage of a small amount of signaling current of different frequency from adjoining blocks, the same as described with reference to Fig. 7.

Various other embodiments of my invention may 'be made as will occur to those skilled in the art, without departing from the scope of my invention.

Having thus described my invention, I declare that what I claim as new and desire to secure by Letters Patent is,-

1. A block signal system comprising a pair of rails, means for supplying an alternating current for propulsion of the cars, the said rails being used jointly for the return of the propulsion current, means for supplying an alternating signal current of different frequency from that of the propulsion current to one or more block sections of said rails, a relay motor having a plurality of windings supplied with energy derived from a block section, and means connected in circuit with said motor and with said block section for causing phase displacement of the currents in the windings of said relay motor to cause the same to operate when supplied with said signal current of the block section to which it is connected and for causing insuflicient phase displacement of the currents in said windings to operate the motor when supplied with current of the frequency of the propulsion current.

2. A block signal system comprising a pair of rails, a source of alternating current of certain frequency supplying propulsion current to the cars and to the two rails.

means for supplying'a signal current of different frequency to a plurality of block sections of said rails, a relay motor corresponding to each of said block sections respectively, each of said motors having a plurality of windings, a pair of leads connected across the rails in each of said block sections and supplying energy to its respective relay motor, and means in the circuit of each of said pairs of leads respectively for causing V a phase difference in the windings of the motor when supplied with said signal current for operating the motor and for causing insufficient phase difference in the windings of the motor to operate the same when supplied with propulsion current.

3. A block signal system, comprising a source of alternating current propulsion energy supplying the cars and the two rails, signals. a source of signal current of different frequency from that-of the propulsion current and supplying alternate block sections, a second source of signal current of different frequency from that of the propulsion current and from that of said first named signal current supplied to the alternate intermediate block sections, a relay motor corresponding to each alternate block section and supplied with energy from its respective block section, each of said motors having a plurality of windings, means controlled by each of said relay motors for controlling the operation of its respective signal, means-in the circuit of each of said relay motors for affecting the phase of the current in the windings of said motors to cause the same to operate in a direction to control the closing of the circuits of their respective signals when supplied with energy from one of said sources, for causing operation in the opposite direction when supplied with energy from another of said sources and for causing no operation of said motors when supplied with energy from the remaining one of said sources, a relay motor corresponding to each intermediate block section and supplied with energy from its respective block section, each of said last named motors having a plurality of windings, means controlled by each of said last named motors for controlling the operation of its respective signal, and means in the circuit of each of the said last named motors for affecting the phase of the current in the windings of said motors for causing operation of the same in a direction to control the closing of the circuits of their respective signals when supplied with energy from one of said sources, which source is a different one from that causing a similar operation of the first named relay motors, for causing operation in the opposite direction when supplied. with energy from another of said sources and for causing no operation of said motors when supplied with energy from the remaining one of said sources.

4. In a signal system, a source of alternatin g current propulsion energy supplying the cars and thetwo rails, a source of signal current of different frequency from that of the propulsion current and supplying energy to a block section, means for supplying signal energy to a second adjoining block section and having different frequency from that of the propulsion current and from that of the ignal energy of said first named block section, a relay motor having a plurality of windings deriving energy from said first block section, means in the circuit of said motor for causing a phase relationship of currents in the windings of said motor to operate the motor and affect its signal when supplied with signal energy of said first block section. a id for causing the phase relationship between the currents in the windings of said motor when supplied With current of the frequency of the propulsion cur-,

rent or of the signal energy of the second block section to be without effect upon itssignal. a second relay motor having a plurality of windings and deriving energy from the second block section, and means in the circuit of said second motor for causing a phase relationship of the currents in the windings of said motor to operate the motor and a ifcct its signal when supplied with signal energy of said second block section and to cause the phase relationship between the currents in the windings of said second motor when supplied with current of the frequency of the propulsion current or of the signal energy of the first block section to be without effect upon its signal.

a. In a signal system for railways, a source of alternating current pro 'iulsion energy supplying the cars and the two rails. a source of alternating current of different frequency supplying signal energy to one or more block sections, a relay motor having a plurality of windings supplied with energy derived from a block section, and'resistance and reactance in the circuit of said motor for causing phase displacement. of the currents in the windings of said motor to cause the same to operate when supplied with signal energy derived from the block section and for causing insufficient phase displacement of the currents in the windings to operate the motor when supplied with current of the frequency of the propulsion current.

6. In a signal system for railways, a source of alternating current propulsion energy supplying the cars and the two rails,-a source of alternating current of different frequency supplying signal energy to onc or more block sections, a relay motor having a plurality of windings supplied with energy derived from a block section, and means in the circuit of said motor for causing phase displacement. of the currents in the windings of said motor to cause the same to operate and affect its signal when supplied with signal energy derived from the block section and for causing a phase relationship of th currents in the windings of said motor when supplied with current of the frequency of the propulsion current to cause the motor to be without effectupon its signal.

7. In a block signal system. a source of energy supplying alternating propulsion current to the cars and rails, a source of signal energy of different frequency from that of the propulsion current and supplying current to block sections, a plurality of electric relay motors, each of said motors having a plurality of windings and each of said motors supplied with signal energy derived from its respective block section, signal devices controlled by said motors respectively, and resistance and reactance in the circuit of each motor respectively for giving pha displacement of current in the windin s of each motor when supplied with signa energy of the block sections for causing said motors to operate and affect the signal devices and for causing a different phase relationship of current in the windings of'said motors when supplied-with energy of the frequency of the propulsion current so as to be without effect upon the signal devices 8. A block signal system comprising a series of segregated blocks. an alternating current propulsion generator supplying motors on the cars, the propulsion current passing through both rails of the track. a signal generator of different frequency supplying the several track circuits. relay signal motors, each of. said motors having a plurality of displaced windings and each deriving cucrgy from its respective block section. signal devices controlled by said motors respectively, and means for controlling the phase of the currents in the windings of each of said motors when supplied with signal energy to cause the motors to affect the signal devices and for causing a different phase relationship of currents in the same windings of said motors when supplied with the frequency of the propulsion current and thereby be without effect upon the signal devices when the relay motors are supplied with propulsion energy.

9. A block signal system comprising a series of segregated blocks, an alternating current propulsion generator supplying the mo tors on the cars. a signal generator of different freruiency supplying the several track circuits in parallel. a signal relay motor having a plurality of displaced windings. and resistance and reactance in the circuit of said motor for producing a phase difference in the windings of the motor when supplied with current. of the signal frequency and no substantial phase difference with the frequency of the propulsion current, whereby the motor will hold the signal at a definite indication under signal current, but will be immune from interference by propulsion current. v

In testimony whereof I affix my signature, in presence of two witnesses.

JAMES BURKE.

Witnesses:

E. G. Jonr N, H. O. CHAPjfZ.

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