US3345511A

US3345511A - Rapid transit steed control system

Info

Publication number: US3345511A
Authority: US
Publication date: 1967-10-03
Anticipated expiration: 1984-10-03

Description

Oct. 3, 1967 E. STAPLES RAPID TRANSIT SPEED CONTROL SYSTEM 8 Sheets-Sheet 1 Filed July 9, 1965 Exit Hahn/we.

i- 4Y Fame A 4 4 m T M 2 4 L @3 WE? m HUMM M 1 M T w 5 W w M w a m w w 6W3? E3 m WWL zzvmswa oa Ugawfofld 1 Sqpbzs B Oct. 3, 1967 Filed July 9, 1965 C. E. STAPLES 8 Sheets-Sheet 2 j 731/ 115% 65! 1 21p 72W WW1 lZ/W ms 2'' 2 1 0TB m4 1? m1 5 1 02 m g {w :u I I 31 I l 1 l 3 L i 1 a i y E L Ll:a 1

i L LIZ A WTOHNEI/ Oct. 3, 1967 c. E. STAPLES 3,345,511

RAPID TRANSIT SPEED CONTROL SYSTEM Filed July 9, 1965 8 Sheets-Sheet 4 INVENTOR. Gaza/fond E. Sta ales.

kJ-LW Hi5 KI'TOEIVEY Oct. 3, 1967 c. E. STAPLES RAPID TRANSIT SPEED CONTROL SYSTEM 8 Sheets-Sheet 6 Filed July 9, 1965 E'rzZ En T W 5:--- z m w a u b 1 V L m 1 m w T '2 W 4 Lb W Z..@ i. 11 w ,r l 5 a W i 5 W I H W w W w W w mvswTok. ET SW61;

Crawford BY W-AW- Oct. 3, 1967 c. E. STAPLES 3,345,511

RAPID TRANSIT SPEED CONTROL SYSTEM Filed July 9, 1965 8 Sheets-Sheet 8 r 361 r 5 Tee 7 12] 0171 m4 R W05 n TCI- 1 my. a.

INVENTOR. Cra wfo d E. Sta Dies.

BY 4 AS w Hi5 ATTORNEY United States Patent Ofiiice 3,345,51 l Patented Oct. 3, 1967 3,345,511 RAPID TRANSIT SPEED CONTROL SYSTEM Crawford E. Staples, Edgewood, Pa., assignor to Westinghouse Air Brake Company, Swissvale, Pa., :1 corporation of Pennsylvania Filed July 9, 1965, Ser. No. 470,713 24 Claims. (Cl. 246-34) This invention relates to a train speed control system.

More specifically this invention relates to a train control system in which there is employed continuous train detection coupled with train signaling to control the speed of the train. The speed control system of this invention may be utilized with either alternating current or direct current propulsion systems in electrified territory.

The advent of modern high speed transit that utilizes electrically continuous rail has brought into focus new problems of train tratfic control. High speeds and the need to maintain closer headway between trains magnify the problems that arise when wayside signaling alone is utilized to control train speed. The invention to be described hereafter does not require wayside signaling as all the speed control signaling appears on the train where the speed control signals may be employed to automatically control the speed of the train, or, on the other hand, allow manual control of the train. Use of the invention will also obviate the need for intermediate control housings by the use of centralized housing to provide all the needed controls. In the practice of the invention there will be utilized rail bonds to define track detection circuits and these rail bonds may be of the type described in the copending application for Letters Patent of the United States, Ser. No. 382,551, filed July 14, 1964, by Ralph Popp, for Electric Induction Apparatus.

This application is an improvement over my copending application for Letters Patent of the United States, Ser. No. 382,620, filed July 14, 1964, for Rapid Transit Speed Control System. The improvement in part stems from the use of an electrically continuous rail system without insulated joints, thereby requiring only one impedance bond per location and only one half the wayside audio frequency transmitters called for in my aboveidentified application.

It is therefore an object of this invention to provide continuous train speed control in a rapid transit system where electrically continuous rails are employed.

It is another object of this invention to provide a speed control system that allows closer headway at all operating speeds and all degrees of track occupancy.

Another object of this invention is to provide a train speed control system in which there are no conflicting speed control signals fed to the train, thereby providing continuous speed control of the train.

Yet another object of this invention is to provide a highly efficient and economical rapid transit speed control system that makes simultaneous use of a plurality of center fed track circuits and train speed control circuits to accomplish this object.

In the attainment of the foregoing objects there is utilized a system which includes an electrically continuous rail and a train having a speed control receiver located on the train. The rails have a plurality of bonds spaced along the rail with wayside transmitters for controlling track relays coupled to alternate bonds to form a plurality of center fed track circuits. Each of the center fed track circuits mutually includes an intermediate bond, and each of the wayside transmitters has at least two wayside receivers for controlling track relays, one receiver at each of the bonds immediately adjacent the bond to which the associated wayside transmitter is fed. This center fed track circuit therefore establishes two track circuit detection sections, the track circuit detection sections having both an entrance end and an exit end defined by the bonds aforementioned. Therefore, by definition every entrance end of a track detection section is also an exit end of a preceding track detection section. While the above is true with reference to a pair of center fed track circuits it should be understood that where there are an uneven number of track detection sections there will be at least one situation which will call for one wayside transmitter and only one wayside receiver. To provide a source of train speed control there is a train speed control transmitter electrically coupled to each bond along the rail. The track receivers, just noted, are interconnected through suitable control means such as relays to the train speed control transmitters and control the train speed control transmitters energization. The transmission of train speed control signals to the train via the bonds and the rails occurs when a bond at an entrance end of a track detection section is shunted and there is a simultaneous transfer of the train speed control to the next train speed control transmitter coupled to a bond at the exit end of the track detection section. Accordingly, the train speed control signals are always being delivered to the rails at the exit end of a track detection section, which exit end as aforementioned is also the entrance end of the next succeeding track detection section. This speed control signal which is applied to the rails is picked up inductively from the rails by receiver coils carried on the front of the train. The speed control signal is then fed to the train speed control apparatus on the train and this results in a continuous speed control of the train.

The invention also contemplates the use of additional wayside receivers interposed between the bonds along the rail to provide additional track detection circuits which will allow further speed control capabilities as when especially close headway must be maintained in station areas.

The entire system relies on the simultaneous presence in the rails of audio frequency energy for the track detection circuitry and train speed control signals of differing frequency for control of the trains speed.

Other objects and advantages of the present invention will become apparent from the ensuing description of illustrative embodiments thereof, in the course of which reference is had to the accompanying drawings, in which:

FIGS. 1 and 2, adapted to be arranged end to end with FIG. 1 on the left, illustrate a circuit diagram incorporating the invention.

FIGS. 3 and 4, adapted to be arranged end to end with FIG. 3 on the left, illustrate one form of usage for the track circuits of FIGS. 1 and 2.

FIGS. 5 and 6, adapted to be arranged end to end with FIG. 5 on the left, illustrate one situation where a train is present at a station platform and a second train is approaching.

FIGS. 7 and 8, adapted to be arranged end to end with FIG. 7 on the left, illustrate a situation where a train is located at the exit end of a station platform and a second train is approaching.

Reference is now made to FIGS. 1 and 2 in which one form of the system embodying the invention is illustrated. In these figures there are present a plurality of track circuits. Basically, a track circuit, by definition, includes a source of electrical energy, the running rails of a section of track, at detecting means which is usually a track relay, and a means for coupling the source and the detecting means to the rails. Such is the case in FIGS. 1 and 2. From a study of these figures it will be evident that no insulated rail joints appear along the

rails

17 and 18. Therefore, since one of the purposes of this invention is to provide the ability for closer headway between trains,

there will be seen that short track circuits have been employed, but these short track circuits do not require the use of insulated rail joints with the accompanying additional cost which arises when insulated rail joints are used to provide boundaries for short track circuits. In the instant application rail bonds aid in defining many of the track circuits involved in this invention.

In FIG. 1, for purposes of illustration only, there is depicted a rail bond with primary winding 16 between the

rails

17 and 18. At the center of the primary winding 16 is a center tap terminal 32 and a lead 33, which lead 33 may be attached to a similar center terminal of a rail bond across the rails of a parallel set of tracks, not shown. In the alternative, this lead '33 may be connected to propulsion return feeders or to grounded structures which thereby aid in the reduction of the voltage drop between the rails and between the train and the power source. The rail bond serves the important function of equalizing the propulsion return between the rails, while simultaneously affording a convenient means of impressing and receiving signals to and from the rails. The minimizing of the voltage drop between the train and the power source allows the train to operate with a higher potential which thereby enhances train operation. The maintenance of a minimum voltage differential between the rails is necessary to prevent interference with signals applied to the rails as will be described hereafter. While none of the remaining rail bonds illustrated in the remaining figures contain this center tap arrangement, it is to be understood that in the actual construction of this system such center tap connections would be made. This, of course, is applicable where the system to be described is used in electric propulsion territory where the running rails are used for propulsion return current. It should be further understood that where the system is employed in non-propulsion territory, that is, where the running rails are not used for propulsion return current, the use of cross bonding is not necessary and a suitable transformer may be substituted to apply to and receive from the rail signals.

This invention will make use of a plurality of audio frequency track circuits which will provide a number of track detection sections which will be employed to detect the presence of a train at any point along the rails.

While not illustrated in the drawings, it should be understood that conventional power supply connection terminals would be present and connected to the various transmitters, receivers and relays to be described. Since the addition of these power supply terminals would only tend to clutter the figures, they have not been shown.

The audio frequency track circuits take the form of center fed track circuits. A typical track circuit arrangement can be seen in a study of the right-hand portion of FIG. 2 where a wayside transmitter TZW is transmitting a predetermined audio frequency. In order to distinguish between different frequencies transmitted, the wayside transmitters have been designated TZW, TSW and T4W. While the normal range of frequencies employed in the practice of this invention is between 1 kc. and 6 kc., it should be understood that the invention includes within its purview the use of frequencies that may fall on either side of the range just noted. The use of these frequencies that fall outside the range aforementioned will depend upon the parameters involved in the track circuits employed and the use to which the system has been designed.

The wayside transmitter TZW feeds the audio frequency energy to a secondary coil 19 which in turn is inductively coupled to a primary coil 12, which primary coil is an integral part of one of the rail bonds between the

rails

17 and 18. One of the track detection circuit paths is formed by the wayside transmitter T2W through the inductive coupling of the secondary coil 19 and primary coil 12, thence through the rail 17, through the primary coil 13 of another rail bond, and back along the rail 18. Adjacent the primary coil 13 there is located a secondary coil 22 which inductively picks up the audio frequency signal present in the primary coil 13, and this signal passes via the leads from the secondary coil 22 to the wayside receiver R2W2 where the audio frequency signal energizes the wayside receiver R2W2 and related track relay TR2 to maintain track relay TR2 in a picked-up position. The wayside receiver R2W2 is tuned to the audio frequency output of the wayside transmitter TZW.

A second train detection track circuit can be seen to the right of the primary coil 12 which forms a part of the rail bond between the

rails

17 and 18. In a like manner, the audio frequency energy in the transmitter TZW is conveyed via the leads from the transmitter TZW to the secondary coil 19 and thence inductively to the primary coil 12, along the rail 17, through the primary coil 11 where the secondary coil 21 inductively picks up the audio frequency signal from the transmitter TZW, and thence back along the rail 18. The wayside receiver R2Wl which is connected to the electrical leads from the secondary coil 21 is energized when no train is present in section 1T. With this receiver R2W1 and its related track relay TR1 energized there is seen a second track detection circuit which appears as a result of the center fed arrangement just described.

Since in my present invention insulated rail joints are not used except at interlockings, there is a short extended shunt area beyond the limits of the track circuits defined by the rail connections for the audio frequency transmitters and receivers hereinafter referred to as AF transmitters and receivers. These extended shunt areas appear in the region of the

bonds containing coils

11, 12 and 13 in the center fed track circuit just described. In each of FIGS. 1 to 8, the arrow heads which designate the length of track detection sections have been purposely extended beyond the vertical reference lines that have been illustrated at each bond along the

rails

17, 18. This extension of the arrow heads is intended to convey the presence of the extended shunt region just discussed. This center fed track circuit just described that includes wayside transmitter TZW therefore has two track detection sections which have been designated 1T and 2T. Whenever a train appears with its wheels shunting the rails just before the rail bond containing coil 13 is the extended shunt area, the circuit to the wayside receiver R2W2 will be shunted and the wayside receiver R2W2 and related track relay TR2 will be deenergized, thereby releasing or dropping the track relay TR2 contacts a and b. In a similar manner, when a train appears in the track detection section 1T, there will be a similar shunting action and the wayside receiver R2W1 and its related track relay TR1 will be deenergized with the resulting release of the contacts a and b of track relay TR1.

As has been pointed out earlier there is a transmitter to provide a speed control signal to the train via the rails, and each rail bond which defines a track detection section has a transmitter electrically coupled thereto. Therefore, with reference to the track circuit just described, there is seen a train speed control transmitter TC1 electrically coupled via its leads to the secondary coil 21 which inductively is coupled to the primary coil 11, which coil is a part of the rail bond connecting the

rails

17 and 18. This transmitter TC1 when energized sends a signal to the rails, which signal when received by the train determines the speed at which the train will travel. It should be understood that the trains that travel on the rails just described have coils mounted on the front of the train which inductively receive any train control signal present in the rails and transmit these signals to the associated control apparatus on the train where they are utilized to control the speed of the train. The precise arrangement and operation of these coils may be found in a description thereof in my copending application for Letters Patent of the United States, Ser. No. 382,620, referred to hereinbefore. In this application there is set forth in detail the precise arrangement for receiving the train speed control signals which emanate from a transmitter electrically coupled to the rails.

In carrying out the invention the train speed control signals from the transmitters TC are normally of a lower frequency range than the audio frequency signals supplied to the track detection sections. Since the impedance of the rails to signals applied to the rails increases as a function of the increase in frequency, the lower the frequency the longer the track detection section may be designed. It is therefore prudent to select a train speed control signal of 'a frequency lower than that frequency selected for the track detection circuitr for the reasons that follow. As has been noted there is at each bond an extended shunt region the length of which is determined by the audio frequency involved and such variable parameters as the adjustment, the length of the circuit, and the ballast resistance. Accordingly, for any one set of conditions it is important that the train speed control signal reach the receiver coils whenever the train has entered the extended shunt region. The lower frequency of the train speed control signal assures that the train will receive the train speed control signal because the lower frequency faces less impedance and can therefore travel the length of the extended shunt region, thereby avoiding the possibility of loss of continuous train speed control. This ability to provide continuous train speed control effectively removes what is termed the gray area of train speed control, the gray area" referred to being that region in the train speed control system where there may arise a discontinuity in train speed control.

As has been pointed out, this system is comprised of a plurality of center fed track circuits, each of which has been defined by rail bonds across the rails, and each of these center fed track circuits provides what are to be termed a pair of track detection sections. In the instance just described, the track detection sections are sections IT and 2T, and as has been noted, at each of the rail bonds of the center fed track circuits there are speed control transmitters electrically coupled to the rail bonds. Train speed control transmitter TC! is connected to the secondary coil 21 and coupled to the primary coil 11 and transmitter TC2 is connected to the secondary coil 19 and coupled to the primary coil 12, and transmitter TC3 is connected to the secondary coil 22 and coupled to the primary coil 13. These primary coils are part of the rail bonds that define the track detection sections IT and 2T. The rail bond which incorporates the primary coil 13 may be viewed as the entrance end of the track detection section circuit which includes the wayside receiver R2W2, and the exit end of this track detection section by definition will be at the rail bond which includes the primary coil 12. In a like manner, the entrance end of the track detection section IT by definition will be at the rail bond which incorporates the primary coil 12, and the exit end of this track detection section will be at the rail bond which incorporates the primary coil 11.

The invention contemplates the incorporation of additional wayside control receivers to provide additional controls to the track to allow closer headway between trains. The precise functioning of these additional wayside receivers and their related track relays will be discussed in detail more fully hereinafter.

The next center fed track circuit arrangement to the left of the center fed track circuit arrangement just defined has a wayside transmitter TSW electrically coupled via its leads and secondary coil 23 to the primary coil 14 of the rail bond which interconnects the

rails

17 and 18. This transmitter T3W supplies audio frequency energy which differs from the frequency transmitted by transmitter T2W. It should be understood that the designation of 3 is meant only to symbolically indicate a different audio frequency from that of the transmitter T2W which is operating at an audio frequency of 2. In a like manner, the other transmitter T4W depicted in FIG. 1 feeding the track detection sections 6T and ST is a transmitter operating at an audio frequency which differs from the frequency of transmitters T2W and T3W. The designations of T4W, T3-W and TZW are not meant to in any way limit the invention but are meant to be illustrative of different audio frequencies which may be used in adjacent sections of track.

The second center fed track circuit which incorporates the wayside transmitter T3W will include the track detection sections ST and 4T. The first track detection circuit to be described includes the wayside transmitter T3W, the secondary coil 23 and its inductive coupling to the primary coil 14 of the associated rail bond, the

rails

17 and 18, and the primary coil 15 of the rail bond in track section 4T. The secondary coil 24 inductively receives the audio frequency energy present in the

rails

17 and 18 and the coil 15 of the associated rail bond. This energy travels along the leads leading from the secondary coil 24 to the wayside receiver R3W2 which is energized along with its related track relay TR4 to maintain the contacts a and b of track relay TR4 in a picked-up position. The second track detection circuit involved in this center fed arrangement involves the track section 3T and includes the wayside transmitter TJW, the secondary coil 23, and its inductive coupling to the primary coil 14 of the associated rail bond. This circuit also includes the

rails

17 and 18 and the rail bond that includes the primary coil 13. The audio frequency energy from the transmitter T3W is inductively coupled to the secondary coil 22, and this audio frequency energy energizes the wayside receiver R3W1 and in turn its related track relay TR3 to maintain the contacts a and b of track relay TR3 in a picked-up position.

Each of these track section-s 3T and 4T, in a similar manner to track sections IT and 2T, has entrance and exit ends of the respective

track detection sections

31 and 4T defined by the rail bonds which form a part of the center fed track circuit.

There is also included in this center fed track circuit the provision of additional wayside control in the form of intermediate wayside receivers R3W4 for track section 4T, and R3W3 for track section 3T. These receivers are connected across the rails and are energized by energy received from the wayside transmitter T3W, which energy is translated from the leads of the transmitter T3W to the secondary coil 23, thence to the primary coil 14 of the rail bond, and along the

rails

17 and 18 to the leads which come from the wayside receiver R3W4. This forms a complete circuit with the wayside receiver R3W4 and the wayside transmitter T3-W. The receiver R3W4, which is tuned to the audio frequency 3 of the transmitter T3-W, is energized and its related track relay TR4A is energized to maintain its contact a in an unreleased position. In a similar manner, for the track detection section 3T, there is a wayside receiver R3W3 and this wayside receiver is energized by the audio frequency energy present in the

rails

17 and 18, this energy having been transmitted from the wayside transmitter TSW via its leads to the secondary coil 23, thence to the primary coil 14 of the rail bond, along the

rails

17 and 18, and thence to the leads of the wayside receiver R3W3, which receiver R3W3 is tuned to the audio frequency 3 of the transmitter T3W. The energization of the receiver R3W3 results in the energization of the track relay TR3A and this track relay TRZrA maintains its contact a in a picked-up position.

The third center fed track circuit, which includes the control of track sections ST and 6T, has a transmitter T4W whose leads are connected to a secondary coil 26 which is inductively coupled to the primary coil 16 of the rail bond in a manner similar to the center fed track circuits just described. The wayside transmitter T4W is operating at an audio frequency designated as 4 and this audio frequency energy is transferred from the secondary coil 26 to the primary coil 16, thence along the

rails

17 and 18 to provide energy in the primary coil 15 of the rail bond at the exit end of track section ST. The audio frequency transmitted by T4W is of course different from that transmitted by T3'W. This energy is inductively coupled to the secondary coil 24. the energy passing along the leads which lead from the secondary coil 24 to the wayside receiver R4W1, which wayside receiver is energized along with its track relay TRS to maintain the track relay TRS contacts a and b in a picked-up position. The second circuit of this center fed arrangement includes a rail bond with a primary coil 30 shown to the left in track detection section 6T. There is as with the other track detection sections a wayside receiver R4W2 electrically coupled to the primary coil 30 by a secondary coil 31, which secondary coil is in turn connected by leads to the wayside receiver R4W2. The leads of a train speed control transmitter not shown are depicted connected to the leads from the wayside receiver R4'W2. There is incorporated in this center fed track circuit arrangement an additional Wayside control which will affect the speed control signals and this takes the form of wayside receiver R4W3 connected across the rails of track section ET. This additional wayside receiver R4W3 is maintained in an energized condition from energy transmitted by wayside transmitter T4W and transferred via the inductive coupling between the secondary coil 26 and the primary coil 16 of the rail bond which interconnects the

rails

17 and 18. The energy from the transmitter T4W passes along the

rails

17 and 18 to the primary coil 30 where the energy is coupled to the secondary coil 31 and thence to the leads of the Wayside receiver R4W2 to maintain energized the relay TR6 to keep the track relay TR6 contacts a in a picked-up position. The wayside receiver R4W3 and its related track relay TRSA receive energy from the transmitter T4W which energy passes along the

rails

17 and 18 to the leads of the wayside receiver R4W3 to maintain energized the relay TRSA.

It can therefore be seen that a single audio frequency transmitter, as shown in FIGS. 1 and 2, may feed two track circuits, one in each direction along the track. It, of course, should be noted that different audio frequencies must be used on adjoining track circuits but frequencies may be repeated at suitable intervals. It should be recognized that all of the audio frequency center fed track circuits shown in FIGS. 1 and 2 are continuously energized. It will be seen in a further study that this will allow a continuous indication of track occupancy.

To be explained more fully hereinafter will be the function of the train speed control transmitters TCl, TCZ, TC3, TC4, TCS and TC6, each of which has been electrically coupled via leads to the rail bonds that define the various track sections from IT through 6T. Each of these transmitters applies a speed control signal to the exit end of a track circuit only when the track circuit is shunted and when traffic conditions ahead permit. Thus, as a train approaches a track circuit and enters what has been previously defined as the extended shunt area, a track relay is shunted cutting off speed control energy from a train speed control transmitter at the entrance end of the track circuit and simultaneously applying speed control energy from a train speed control transmitter at the exit end of the track circuit. The signals that may be applied will be either an authorized speed command or a limited speed command. These two different levels of speed are not the only possible speed command signals that could be made available to a train operating on the tracks incorporating this invention. As has been pointed out, when a train occupies a detection section of a track circuit, train speed control energy from one of the transmitters TCl through TC6 will apply energy to the exit end of the track circuit and this may be applied at a coded rate as has been described in my copen-ding application, Ser. No. 382,620, referred to hereinbefore This coded rate and carrier frequency that is transmitted will be indicative of the occupancy of the various track sections along the rails, and the particular frequency transmitted to the train speed control apparatus from the transmitters, will be indicative of speed required for the train for the traflic conditions present within the system. It is also important to recognize that no train speed control signaling energy will be applied to the track circuit if the track circuit immediately ahead is occupied. The absence of a speed control signal therefore represents the most limiting speed control command and this limiting speed control command will cause the train to brake to a stop. The precise manner in which this occurs will be described more fully hereafter.

For purposes of explanation in this application there will only be three cab signaling conidtions utilized. They will be first, an authorized speed command A, and secondly, a limited speed command L, and finally if there is no signal at all to the rails from the cab transmitters, this will be indicative of the most restrictive speed and therefore will indicate to the train-carried equipment that the train should proceed into a braking action to bring the train to a halt.

It should be understood that while throughout the remaining FIGS. 3 to 8 the source of these speed control signals will not be shown, there is normally provided a centralized control center from which the train speed control signals originate. This centralized control center will therefore provide a point at which the entire system may be monitored for purposes of train control with reference to track occupancy and rail characteristics (curved or straight sections of track).

A study of track detection section 1T will reveal that it can receive a train speed control signal from transmitter TCI. This signal has been designated by the reference numeral L. Accordingly, a limited command signal L can be applied over the front contact a of track relay OTR, over the back contact a of track relay 'IRl, and thence to the transmitter T01 and its leads which lead to the secondary coil 21, which limited speed control signal in coil 21 in turn impresses upon the primary coil 11 of the rail bond the train speed control signal which then will appear in the

rails

17 and 18, which will in turn be inductively detected by the coils which are carried by the train and in turn the signals inductively received by the coils on the train will provide a signal to the train speed control apparatus to command the speed designated in this particular instance L, or a limited speed command.

The transmitter TCZ for track detection section 21 can be set to receive a limiting speed control signal L. This circuit is completed over the front contact b of track relay TRl via the electrical connections to the back contact a of track relay TR2, to the transmitter TC2 and thence to the secondary coil 19 where it is inductively coupled to the primary coil 12 of the rail bond that joins the

rails

17 and 18.

In a similar manner, track detection section 31 is fed by a transmitter TC3 which may receive a limiting speed control signal L over the front contact b of track relay TRZ, and thence over the back contact a of track relay TR3, and then to the transmitter TC3 and finally to the track detection section 3T in a manner similar to that described with reference to track detection sections IT and 2T.

In a similar manner, track detection section 4T is fed by a transmitter TC4 and this transmitter TC4 may be alternately fed by a limiting control signal L over the front contact a of track relay TR'3A, thence over the front contact a of track relay TR4A, and next over the back contact b of track relay TR4, and thence to the transmitter TC4 which in turn sends this limiting control signal L to the

rails

17 and 18 of track detection section 4T. In this particular instance, there is a second path for a limiting control signal L to the train and this limiting control signal L can be applied over the front contact b of the track relay TR3, and thence over the back contact a of track relay TR4A, and next over the back contact b of track relay TR4, and thence to the transmitter TC4 to be applied to the rails in a manner similar to that just described.

Track detection section T can also receive a limiting speed control signal L. This speed control signal will be applied and pass over the front contact a of track relay TR4, thence over the back contact a of track relay TRS, and to the transmitter TCS, and thence to the

rails

17 and 18 via the inductive coupling between the coils 24 and in a manner similar to the previously described track detection sections.

The last train speed control transmitter is TC6, shown on the left-hand side of FIG. 1, and it may receive either a limiting speed control signal L or an authorized speed control signal A. The limiting speed control signal would travel over the front contact a of track relay TRSA, and thence over the back contact b of track relay TRS, and thence to the back contact a of track relay TR6, and then to the transmitter TC6 to apply a limiting control signal L to the rails in a manner that has been previously described.

It will be understood that track detection section GT is some distance from the station platform designated to the right in FIG. 2, and as such represents only the first track detection section that appears as the rails pass away from the train station, and therefore in this section 6T and the sections that would appear to the left of 6T there is a need for an authorized speed control to permit the train to travel at the authorized speeds along the rails. Therefore, it can be seen that an authorized command signal designated A may be fed over the front contact b of track relay TRS, thence over the back contact a of track relay TR6 and thence to the transmitter TC6 to be fed to the rails as has been described earlier. This would provide an authorized speed command A to appear in the

rails

17 and 18 whereafter the signal would be inductively received by the coils of the train and thence translated to the train to provide an authorized command control signal to permit the train to proceed at the authorized speed.

It should be understood that while this application sets forth an environment in which a train or trains are entering a train station, the system is equally applicable to curved sections of track where the speeds of the train must be reduced in order that the train maintains the proper speed for the track conditions involved. Therefore, a system similar to this one in which there are limited or authorized speed controls fed to track detection sections in curved sections of the rails may be employed to slow the train dependent upon the part of track curve encountered. Employment of the system simultaneously al lows a control of headway between trains on all sections of track whether curved, straight, or entering a station area.

It should also be understood that while the invention is set forth in an environment where a train stops or is slowed as it passes a station, this is not intended to limit the actual use of the system. The invention therefore contemplates the use of train speed control signals which will allow a train to maintain authorized speed through a station with stops for example at every other station. In other words any train speed control pattern may be established at a centralized control point dependent on the use to which the system is sought to be adapted. The train speed control signals to the rails via the inputs A and L throughout FIGS. 1 to 8 may or may not be coded in the manner set forth in my copending application, Ser. No. 382,620, hereinbefore referred to, in which this coded arrangement was set forth in some detail.

Operation of the system In describing the operation of the system, reference is now made to FIGS. 3 and 4, in which there is illustrated the system depicted in FIGS. 1 and 2 with the addition of a train X shown in dotted lines in a number of positions along the

rails

17 and 18, the positions being X1, X2,

X3, X4, X5, X6 and X7. The precise manner in which the system operates will now be described with the train X approaching the station from the left-hand side of this figure passing to the right. When the train X is in the X1 position, the wheels of the train shunt the

rails

17 and 18 and in so doing deenergize the circuit that includes the wayside transmitter T4W which has impressed on the

rails

17 and 18 the audio frequency energy which has been energizing the wayside receiver R4W2 and its related track relay TR6. With the wheels across the

rails

17 and 18, the wayside receiver R4W2 is deenergized and the track relay TRfi releases, thereby closing the back contact a of relay TR6. It will therefore be seen that a circuit is completed between the authorized speed control input A over the front contact b of track relay TRS and the back contact a of track relay TR6, thence to the transmitter TC6, which places upon the rails the authorized speed command A via the inductive coil 26 and the related primary winding 16 of the rail bond. This transmitter control signal travels along the

rails

17 and 18 where it is inductively picked up by coils (not shown) carried on the front of the train and thence to a train speed control apparatus 27.

As the train passes from position X1 to position X2, the front of the train as it approaches the rail bond which includes the primary coil 16 enters what is termed an extended shunt area, that is, a region shortly before the rail bond in which the wheels of the train actually shunt the energy being delivered from the wayside transmitter through the wheels of the train rather than allowing the normal energy path through the rail bond to occur. This extended shunt area varies in length depending upon the signaling frequency, the length of the circuits, and the ballast resistance present in the tracks at the rail bond location. It should be understood that these extended shunt areas, which typically may vary in the region of 30 feet or more, will appear at either side of the rail bond. For purposes of illustration only, each of the trains depicted proceeding from left to right in this figure will be shown exactly at the rail bond for purposes of explaining how the related wayside circuitry functions to produce a command control signal to be delivered to the rails which in turn control the speed of the train.

When the train is in position designated X2, the front wheels of the train will shunt the energy between the

rails

17 and 18, the energy being delivered from the wayside transmitter T4W. Therefore, the wayside receivers R4W3 and R4W1, which are in track detection section 5T, will be deenergized and their related track relays TRSA and TRS will also be released due to the deenergization of their respective receivers. The train in this position is now entering the entrance end of track detection section 5T, while simultaneously leaving the exit end of track detection section 6T. When it does so the track relay TRSA, as has been noted, releases and its contact a opens, thereby removing any possibility for the limited speed control command signal L to be applied to the track detection section 6T immediately behind the train in the X2 position. It should be noted also that since track relay TRS is also released, the authorized speed control signal A cannot be applied to the transmitter TC6. The deenergization of track relay TRS causes the closing of back contact a of the relay TRS. It will be seen that there is then a complete circuit for the limited speed command control signal L over the front contact a of track relay TR4, thence over the back contact a of track relay TRS, and thence to the transmitter TCS which delivers the limited speed control signal L to the secondary winding 24, thence to the primary winding 15 of the rail bond, and through the

rails

17 and 18. This limited speed control signal travels along the rails and is inductively received by the coils (not shown) mounted in the front of the train, and this signal, that is, this limited control signal L is delivered to the train speed control apparatus 27 of the train and automatically produces a limited speed command which causes the braking of the train to reduce the speed from that of an authorized speed to that of a limited speed.

As the train continues from left to right and enters position X3, the following track circuits are effected. As the train enters the entrance end of the track detection section 4T, the train is therefore entering the second center fed track circuit which has as its source of audio frequency energy wayside transmitter T3W. Therefore, the train wheels which are at or near the rail bond which carries the primary coil 15, shunt the wayside receiver R3W2, thereby deenergizing this receiver and its related track relay TR4, which opens the front contact a of track relay TR4 and closes the back contact b of track relay TR4. It will therefore be seen that there is now a complete circuit which produces a limited speed control L. This speed control L appears over the front contact a of track relay TRSA, thence over the front contact a of track relay TR4A, and thence over the back contact b of track relay TR4, and thence to the transmitter TC4. The signal, which is a limited speed control signal, passes through the electrical leads from the transmitter TC4 to the rails where this signal is inductively coupled via the secondary winding 23 to the primary winding 14 of the rail bond and to the rails, as just noted, and thence to the pickup coils (not shown) of the train in position X3, the speed control signal then being delivered to the train speed control apparatus 27 of the train.

When the train is in position X4, the intermediate wayside relay R3W4 is shunted and the track relay TR4A of this wayside receiver is deenergized. It will be seen that, even though this wayside receiver R3W4 has been deenergized, there will continue a limited speed control to the cab of the train and this limited speed control will appear over the front contact b of track relay TR3, thence over the back contact a of track relay TR4A, thence over the back contact b of track relay TR4, and thence to the transmitter TC4 to apply a limiting control signal to the rails in the same manner that has just been described.

When the train enters position X5 the wheels of the train will shunt the circuits that are fed by the wayside transmitter T3W in the track detection section 3T. Therefore, the wayside receiver R3W3 and its related track relay TRSA will be deenergized as will be the wayside receiver R3W1 and its related track relay TR3. This will result in the opening of the normally closed contact a of track relay TR3A and the closing of the normally opened contact a of track relay TR3, as well as the opening of the normally closed contact b of track relay TR3. This results in a limited speed control signal L over the following circuit. The limiting speed control signal L will therefore follow a path over the front contact b of track relay TRZ, thence over the back contact a of track relay TR3, and thence to the transmitter TC3 which will then apply the limited speed control signal via the

coils

22 and 13 to the

rails

17 and 18 in a manner similar to that previously described. The train, therefore, in position X5 will receive a limiting control signal, which signal will be the same as the limiting control signals previously received as the train approached the station.

Upon reaching the position designated X6 the train will be leaving the track detection section ST and entering the track detection section 2T, which will result in the shunting of the

rails

17 and 18 to produce the deenergization of wayside receiver RZWZ which is normally energized from the center fed circuit which has as its source of energy the wayside transmitter T2W. The deenergization of the wayside receiver R2W2 and its related track relay TRZ will close the normally opened contact a of track relay TRZ and open the normally closed contact b of track relay TRZ. This will result in the following limited speed control signal circuit. The limiting speed control signal circuit will be over the front contact b of track relay TRl, thence over the back contact a of track relay TR2, and thence to the transmitter TCZ which will apply this limiting control speed signal to the rails in the same manner previously described. It can therefore be seen that the train in position X6 is continuously receiving as it enters and leaves the track detection section a limiting control signal, and as the train enters one section and leaves another there is a continuity of limited speed control signals constantly being applied to the rails to be inductively received by the pickup coils of the train. The coils of the train in turn allow the transmission of the limited control signal to the train speed control apparatus 27 of the train to produce the requisite automatic control of the train speed.

There is one further position shown where the train is near the end of the station platform and is in position X7. When the train is in this position, the train has now entered the entrance end of track detection section IT and in so doing has shunted the energy being delivered by the wayside transmitter TZW to the

rails

17 and 18, and in so doing has deenergized the wayside receiver RZWI and its related track relay TRl, which results in the closing of the normally open contact a of track relay TRl and the opening of contact b of the normally closed contact of track relay T R1. Therefore, it will be seen that a limited control signal will be applied to the rails to be delivered to the train in position X7 over the following circuit. The limiting control signal will be applied to and over the front contact a of track relay OTR, thence over the back contact a of track relay TRI and thence to the transmitter TCl which in turn delivers the limited speed control signal to the rails in a manner similar to that described with reference to track detection sections 2T through 6T.

Reference is now made to FIGS. 5 and 6 which depict the same track circuit system illustrated in the earlier figures just described. This set of figures is intended to convey the functional operation of the track relays that are at the wayside and the related train speed control transmitter signals as they are applied to the rails to command the control of the train speed as it enters a station where there is already a train stopped on a section of track. It should be understood that while these figures illustrate what appears to be a static condition for a number of positions of a train entering a station, it is intended to convey the concept that the system is a dynamic system in which trains are constantly moving and the trains depicted in these two figures are meant to be viewed as being stopped instantaneously in their transit along the rails. For purposes of explanation the system will be described as in a static state for purposes of easing the explanation of the related circuitry.

In FIGS. 5 and 6 there are two trains depicted. The train W with its train speed control apparatus 29, which is stopped in track detector section 3T, is shown in heavy lines, while a train approaching the station from left to right designated train V, shown in positions V1, V2 and V3, is a train approaching the now stopped train W. With train W stopped where it is, the wheels of the train across the

rails

17 and 18 shunt the center fed track circuit which includes the track section 3T. The transmitter which feeds the audio frequency signals to this section of rail is transmitter T3W, and since the train wheels shunt the rails before the wayside relay receiver R3W3, the wayside receiver R3W3 is therefore deenergizted along with its related track relay TR3A, and the contact a of rack relay TR3A is opened. Also, the wayside receiver R3W1 is shunted by the presence of the train W in the track section ST. The train W shunts the

rails

17 and 18 and thereby deenergizes the wayside receiver R3W1 and its related track relay TR3. This results in the closure of the back contact a of track relay TR3 and the opening of the front contact b of track relay TR3. It can therefore be seen that a limiting control signal L will be then applied across the front contact b of track relay TR2, thence across the back contact a of track relay TR3, and thence through the transmitter TC3 where this limiting signal will be applied to the rails via the

coils

22 and 13 in a manner previously described. This limiting control signal of course is being applied when the train is in its dynamic or moving state. It should again be noted that the contact a of track relay TR3A is now open as well as the contact b of track relay TR3.

As the train V in position V1 approaches from left to right in this figure and into position V1, the wheels of the train will shunt the rails in the track section 6T and therefore the transmitter energy from wayside transmitter TW4 will not be received by the wayside receiver R4W2 and this wayside receiver will then be deenergized along with its related track relay TR6. This will cause the contact a of track relay TR6 to be released and come in contact with the back contact of rack relay TR6. It can then be seen that there is an authorized speed command signal A which will be then applied across the front contact b of track relay TR5, thence over the back contact a of track relay TR6, and thence to the transmitter TC6 where this authorized speed command signal A will be delivered to the rails and the train speed control apparatus 28 in a manner similar to that previously described. This authorized signal when applied to the rails will be received by the train V in the V1 position and this will permit the train to maintain its authorized speed at a maximum speed in this section of track.

When the train passes through track section 6T and enters the entrance end of section T, the following circuits will be effected. Since the train V in position V2 effectively shunts all the energy from the wayside trans mitter TW4 through the wheels of the train, intermediate wayside receiver R4W3 will be deenergized along with its track relay TRSA and the contact a of track relay TRSA will be opened. Since the wheels shunt the rails and all the energy from the transmitter TW4 passes through the wheels of the train when the train is in position V2, the wayside receiver R4W1 and its related track relay TR5 will also be deenergized, thereby releasing the track relay and closing the back contact a of track relay TR5. The release of the track relay TR5 also causes the back contact b of track relay TR5 to close. This will then provide a limited speed control signal L to be applied over the following path. The limiting speed control signal L will travel along the front contact a of track relay TR4, thence over the back contact a of track relay TR5, to the transmitter TCS where this limited speed control signal L will then be applied to the rails and received by the train speed control receiver 28 in a manner previously described. It can therefore be seen that as the train V leaves position V1 and enters position V2 the signal fed to the rails to control the speed of the train changes from an authorized speed control A or maximum speed to a limited speed control signal L. The train V then proceeds toward the train W which is standing in the station. When the train V approaches the exit end and enters the position shown at V3 at the exit end of track section 51, the following circuits will be effected. Since the train has its wheels shunting the rails in the vicinity of the rail bond at this position, the wayside receiver R3W2 which is normally fed energy from the transmitter T3W is deenergized along with its related track relay T R4 to open the front contact a and close the back contact b of track relay TR4. The following speed control circuit will then occur. It should he remembered that the contact a of track relay TR3A and the contact b of track relay TR3 have both been opened as a result of the train wheels of the train W shunting the rails in the track section 3T. Accordingly, there will be no path which the limiting speed control signals L may follow to reach the transmitter TC4, and since this transmitter TC4, which feeds the track section 4T, is the only means of speed control to the rails and thence to the train speed control apparatus 28 of the train, no signal will therefore be applied to the rails and this will create at the train the most limited or restrictive condition, which is that of braking. In the absence of a signal, as has been already noted, the most restrictive condition is applied and the train automatically receives a braking action in order to bring the train to a halt before collision with the train W in the station.

It can be seen that as this train V approaches the station and while in position V1 there is an authorized speed control and as it proceeds toward the station area decreasing the headway between the trains V and W, the speed control to the rails automatically changes from that of an authorized speed control signal A in position V1 to a limited speed control signal L in position V2 and next to the most restrictive speed control situation in position V3, at which time the train begins to enter the braking operation to bring the train to a halt.

FIGS. 7 and 8 represent a second set of circumstances in which the train is in the station or just leaving the station and a second train is approaching from left to right. In these figures, the train that is approaching from left to right is designated Y, and takes the positions Y1 through Y5, while the train departing from the station or standing in the station is designated Z. With the train Z in this position, the wayside transmitter TZW that feeds this track detection section has its energy, which has been fed to the rails, shunted through the wheels of a train and thereby causes the deenergization of the wayside receiver R2W2 which is normally fed from this transmitter T2W. This deenergization of the wayside receiver R2W2 causes the release of related track relay TR2. This release closes the back contact a and opens the front contact b of track relay TR2. The train speed transmitter control signal in this particular instance will therefore be a limiting speed control signal L which will appear over the front contact b of track relay TRl and thence over the back contact a of track relay TR2 to the transmitter TCZ and thence to the rails and the train speed control apparatus 29 in a manner earlier described.

A study will now be made of the train Y as it approaches from left to right and enters the position Y1 depicted in the left-hand portion of FIG. 7. When the train Y is in the position Y1, the track detection section 6T which the train occupies has the rails shunted and in so being shunted deenergizes the wayside receiver R4W2, which receiver R4W2 is normally being fed from the wayside transmitter T4W. This shunting causes the related track relay TR6 of the wayside receiver R4W2 to be deenergized and released, and therefore the contact a comes to rest on the back contact of track relay TR6. Accordingly, there is applied to the transmitter TC6 an authorized speed control signal A over the front contact b of track relay TR5, thence over the back contact a of track relay TR6, and thence through the transmitter TC6 where this authorized speed control signal is applied to the rails and the train speed control apparatus 30 in a manner earlier described. The train Y therefore in position Y1 is receiving an authorized speed control signal A and may maintain its maximum speed in section 6T of the rails.

When the train enters the position Y2, the following circuits are effected by the presence of train wheels shunting the rails. The transmitter T4W, which normally feeds its energy to the rails to control the wayside receivers R4W1 and R4W3, has been efiectively shunted by the presence of the wheels across the rails in train position Y2. Therefore, no energy from the transmitter T4W is being passed along the

rails

17 and 18 to energize the receivers R4W3 and R4W1. This results in the deenergization and the release of track relays TR5A and TR5 with the concomitant opening of the track relay contact a of relay TR5A and the closing of the contact a of track relay TR5 and the shifting of the contact b from the front contact to the back contact b of track relay TR5. This results in the limiting speed control signal L being applied across the front contact a of track relay TR4 and thence over the back contact a of track relay TR5, and thence to the transmitter TC5 where this limiting speed control signal is applied to the rails and the train speed control apparatus 30 in a manner similar to that earlier described. Therefore, the train in position Y1 receives a limited control speed signal L.

When the train enters the track detector section 4T as it exits track section 4T and is now in the position Y3, the following circuits will be effected by the shunting action of the wheels across the rails. The track relay receiver R3W2, which is normally receiving energy from the transmitter T3W, is deenergized by the shunting action of the wheels across the rails and its related track relay TR4 releases, thereby opening the front contact a of track relay TR4 and closing the back contact b of track relay TR4. This produces the following limited speed control circuit path to the transmitter TC4. This speed control signal L passes over the front contact a of track relay TR3A, thence over the front contact a of track relay TR4A, and neXt over the back contact b of track relay TR4 and thence to the transmitter TC4 where this limited speed control signal is applied to the rails and fed to the train speed control receiver 30 in position Y3. The train, therefore, receives the limiting speed control signal and continues in the manner it was when it received the signal in position Y2, which is in a limited speed control operation.

When the train reaches the position Y4 in track detection section 4T, the following circuits are effected. The wayside receiver R3W4, which is normally energized by the wayside transmitter T3W, has its circuit shunted and therefore the wayside receiver R3W4 is deenergized along with its related track relay TR4A. The release of track relay TR4A, thereby closes the back contact a of track relay TR4A and the following speed control signal path to the transmitter TC4 is present. The limiting control signal L passes over the front contact b of track relay TRS, thence over the back contact a of track relay TR4A, next over the back contact b of track relay TR4, and thence to the transmitter TC4. This limiting speed control signal is then applied to the rails and thence to the train speed control apparatus 30. The train in position Y4 is therefore receiving, as it was in positions Y2 and Y3, a limiting speed control signal.

When the train moves from position Y4 in the center of track detector section 4T to the exit end of track detection section 4T and into the entrance end of track detection section 3T, the following circuits are efiected.

With the train in position Y5 it should be recognized that the train speed control, if any, will have to come from the transmitter TC3, and at this time it should be recalled that with the train Z in the position in the middle of track detector section 2T, the wayside receiver R2W2 and its related track relay were deenergized by the shunting action of the train wheels across the rails, thereby opening the front contact I) of track relay TR2. This in effect stops a limited speed control signal from being applied to the cab transmitter TC3. Therefore, the track detection section 3T, when a train is in the position of train Z, has no train speed control energy signal being delivered to this section of track, and therefore with the train in position Y5, there will be no train speed control signal delivered to the rails, and the train in position Y5 will be in the most limited speed control situation possible, namely, that of a braking condition to bring the train to a halt.

In these two FIGS. 7 and 8, as well as in FIGS. 5 and 6, there has been illustrated the situation where two trains are on the trails at the same time with one train in the station, and it is evident that this system, just described, provides for an automatic speed control of both trains especially the train approaching from the left to the right when a train is already within a station or leaving a station. The description of these FIGS. 5 through 8 therefore illustrates the dynamic manner in which the speed control signals are shifted from an exit end to an exit end of successive track detection sections as a train passes along the rails toward the station which is occupied by another train. It can be seen that the trains go through an authorized speed control condition, thence to a limited speed control, and next when the trains approach too close to each other, relatively speaking that is, the system provides for the automatic removal of train speed signal control energy to the rails, thereby imposing the most restrictive condition to the rails that can be applied.

While the present invention has been illustrated and disclosed in connection with the details of illustrative embodiments thereof, it should be understood that those are not intended to be limitative of the invention as set forth in the accompanying claims.

Having thus described my invention, what I claim is:

1. A train speed control system for use in a system having electrically continuous rails and a train thereon having speed control receiver means to receive a train speed control signal from said rails,

(a) first, second and third bonds interconnecting said rails, each bond having a train speed control trans mitter means electrically coupled to said bond to provide train speed control signals to said rails, and said second bond having a wayside transmitter electrically coupled to said second bond,

(b) said first and third bonds having wayside receivers tuned to the output of said wayside transmitter and electrically coupled thereto to control said train speed control transmitter means so that when said train passes said first bond and then said second bond, said train speed control transmitter means at said first bond and said second bond respectively cease to control said train and there is a simultaneous transfer of speed control to said train speed control transmitter means at said second bond and then said third bond to thereby provide a continuous speed control to said speed control receiver on said train.

2. The train speed control system of claim 1 wherein there is positioned intermediate said bonds at least one additional wayside receiver electrically coupled to said rails to establish an intermediate control point between said bonds, said additional wayside receiver interconnected to said train speed control means so that when said additional wayside receiver is shunted by said train there is provided an additional speed control to said speed control receiver means on said train.

3. The train speed control system of claim 1 wherein said wayside receivers are continuously energized by said wayside transmitter until shunted by said train while said train speed control transmitter means at said second bond and said third bond are only energized when said train shunts said rails deenergizing said wayside receivers at said first bond and said third bond respectively.

4. A train speed control system for use in a system having electrically continuous rails and a train thereon having a speed control receiver means to receive a train speed control signal from said rails,

(a) first, second and third bonds interconnecting said rails each bond having a train speed control transmitter means electrically coupled to said bond to provide train speed control signals to said rails, and said second bond having a wayside transmitter electrically coupled to said second bond,

(b) said first, second and third bonds having an extended shunt region along said rails on the train approach side of said bonds,

(c) said first and third bonds having wayside receivers tuned to the output of said wayside transmitter and said wayside receivers electrically coupled thereto to control said train speed control transmitter means so that when said train enters said extended shunt region of said first bond and shunts said rails, said train speed control transmitter means at said first bond ceases to control said train and there is a simultaneous transfer of speed control to said train speed control transmitter means at said second bond to thereby provide a continuous speed control signal to said speed control receiver on said train.

5. The train speed control system of claim 4 wherein there is positioned intermediate said bonds at least one additional wayside receiver electrically coupled to said rails to establish an intermediate control point between said bonds, said additional wayside receiver interconnected to said train speed control means so that when said additional wayside receiver is shunted by said train there is provided an additional speed control to said speed control receiver means on said train.

6. The train speed control system of claim 4 wherein said wayside receivers are continuously energized by said wayside transmitter until shunted by said train while said train speed control transmitters at said second bond and said third bond are only energized when said train enters said extended shunt region of said first bond and said extended shunt region of said second bond respectively.

7. A train speed control system for use in a system having electrically continuous rails and a train thereon having a speed control receiver means to receive a train speed control signal from said rails,

(a) a plurality of bonds interconnecting said rails, said bonds defining a plurality of track detection sections, each bond having a train speed control transmitter means electrically coupled to said bonds to provide train speed control signals to said rails, wayside transmitters electrically coupled to alternate bonds, each wayside transmitter having at least two way side receivers tuned to the output of said wayside transmitters and wayside receivers electrically coupled to each of the immediately adjacent bonds to control said train speed control transmitters so that when said train passes a bond entering a track detection section said train shunts said rails, said train speed control transmitter means at said bond crossed by said train ceases to control said train and there is a simultaneous transfer of speed control to said train speed control transmitter means at the next bond along said rails.

8. The train speed control system of claim 7 wherein there is positioned intermediate said bonds at least one additional wayside receiver electrically coupled to said rails to establish an intermediate control point between said bonds, said additional wayside receiver interconnected to said train speed control means so that when said additional wayside receiver is shunted by said train there is provided an additional speed control to said speed control receiver on said train.

9. The train speed control system of claim 7 wherein said wayside transmitters have different audio frequency outputs which are in a selected order to thereby avoid possible mutual interference with said tuned wayside receivers, and said train speed control transmitter means which are coupled to said bonds have different frequency outputs dependent on the occupancy of said rails and the track detection section shunted.

10. A train speed control system for use in a system having electrically continuous rails and a train thereon having a speed control receiver means,

(a) a plurality of bonds interconnecting said rails and spaced along said rails, said bonds defining a plurality of track detection sections,

(b) wayside transmitters electrically coupled to alternate bonds,

() each wayside transmitter having at least two wayside receivers tuned to the output of said wayside transmitters and electrically coupled to each of the immediately adjacent bonds,

(d) train speed control transmitter means electrically coupled to each of said bonds and controlled by said wayside transmitters so that when said train passes a bond entering a track detection section said train shunts said rails, said train speed control transmitter means at said bond passed by said train ceases to control said train and there is a simultaneous transfer of speed control to said train speed control means at the next bond along said rails.

11. The train speed control system of claim 10 wherein there is positioned intermediate said bonds at least one additional wayside receiver electrically coupled to said rails to establish an intermediate control point between said bonds, said additional wayside receiver interconnected to said train speed control transmitter means so that when said additional wayside receiver is shunted by said train there is provided an additional speed control to said speed control receiver on said train.

12. The train speed control system of claim 10 wherein said wayside transmitters have different audio frequency outputs which are in a selected order to thereby avoid possible mutual interference with said tuned wayside receivers, and said train speed control transmitter means which are coupled to said bonds have different frequency outputs dependent on the occupancy of said rails and the track detection section shunted.

13. A train speed control system for use in a system having electrically continuous rails and a train thereon having a speed control receiver means to receive a train speed control signal from said rails,

(a) a plurality of bonds interconnecting said rails and spaced along said rails, said bonds defining a plurality of track detection sections, each section having an entrance end and an exit end,

(b) wayside transmitters electrically coupled to alternate bonds,

(c) each wayside transmitter having at least two wayside receivers tuned to the output of said wayside transmitters and electrically coupled to each of the immediately adjacent bonds,

((1) train speed control transmitter means electrically coupled to each of said bonds,

(c) said wayside receivers controlling said train speed control transmitter means so that when said train enters said entrance end of a track detection section and shunts said rails, said train speed control transmitter means at said entrance end of said track detection section ceases to control said train and there is a simultaneous transfer of speed control to said train speed control transmitter means at said exit end of said track detection section.

14. The train speed control system of claim 13 wherein there is positioned intermediate said bonds at least one additional Wayside receiver electrically coupled to said rails to establish an intermediate control point between said bonds, said additional wayside receiver interconnected to said train speed control transmitter means so that when said additional track relay receiver is shunted by said train there is provided an additional speed control to said speed control receiver on said train.

15. The train speed control system of claim 13 wherein said wayside transmitters have different audio frequency outputs which are in a selected order to thereby avoid possible mutual interference with said tuned wayside receivers, and said train speed control transmitter means which are coupled to said bonds have different frequency outputs dependent on the occupancy of said rails and the track detection section shunted.

16. A train speed control system for use in a system having electrically continuous rails and a train thereon having a speed control receiver means to receive a train speed control signal from said rails,

(b) wayside transmitters electrically coupled to alternate bonds,

(c) each wayside transmitter having at least two wayside receivers electrically coupled to each of the immediately adjacent bonds,

(d) train speed control transmitter means electrically coupled to each of said bonds,

(e) each of said bonds having an extended shunt region along said rails on the train approach side of said bonds,

(f) said wayside receivers controlling said train speed control transmitter means so that when said train enters said extended shunt region at an entrance end of a track detection section and shunts said rails, said train speed control transmitter means at said entrance end of said track detection section ceases to control said train and there is a simultaneous transfer of speed control to said train speed control transmitter means at said exit end of said track detection section.

17. The train speed control system of claim 16 wherein there is positioned intermediate said bonds ,at least one additional Wayside receiver electrically coupled to said rails to establish an intermediate control point between said bonds, said additional wayside receiver interconnected to said train speed control transmitter means so that when said additional wayside receiver is shunted by said train there is provided an additional speed control to said speed control received on said train.

18. The train speed control system of claim 16 wherein said wayside transmitters have different audio frequency outputs which are in a selected order to thereby avoid possible mutual interference with said tuned wayside receivers, and said train speed control transmitter means which are coupled to said bonds have different frequency outputs dependent on the occupancy of said rails and the track detection section shunted.

19. A train speed control system for use on electrically continuous rails,

(a) a train on said rails having a speed control receiver thereon,

(b) a plurality of bonds spaced along said rail,

(c) wayside transmitters electrically coupled to alternate bonds to form a plurality of center fed track circuits each mutually including an intermediate bond,

(d) each wayside transmitter having at least two wayside receivers tuned to the output of said wayside transmitter and said wayside receivers electrically coupled to each of the immediately adjacent bonds,

(e) each of said center fed track circuits forming two track circuit detection sections, each section having an entrance end and an exit end defined by said bonds,

(f) train speed control transmitter means electrically coupled to each of said bonds,

(g) said track relay receivers controlling said train speed control transmitter means so that when a bond and related track circuit at an entrance end of a track circuit detection section being fed a train control signal is shunted there is a simultaneous transfer of speed control to said exit end train speed control transmitter means to thereby provide a continuous speed control signal to said speed control receiver on said train.

20. The train speed control system of claim 19 wherein there is positioned intermediate said bonds of said track circuit as least one additional Wayside receiver electrically coupled to said rails to establish an additional intermediate track circuit which intermediate track circuit will include one of said alternate bonds and related wayside transmitter, said additional wayside receiver interconnected to said train speed control transmitter means so that when said additional wayside receiver is shunted by said train there is provided an additional speed control to said speed control receiver on said train.

21. The train speed control system of claim 19 wherein said wayside transmitters of said center fed track circuits have differing audio frequency outputs which are in a selected order to thereby avoid possible mutual interference with said tuned wayside receivers of each of said 20 center fed track circuits, and said train speed control transmitter means which .are coupled to said bonds have different frequency outputs dependent on the occupancy of said rail and which track circuit is shunted.

22. The train speed control system of claim 19 wherein said wayside receivers are continuously energized by said wayside transmitters until shunted by said train while said train speed control transmitter means are consecutively energized at each bond as said bond immediately preceding said energized speed control transmitter means is shunted by said train.

23. A train speed control system for use in electrified territory, said system having electrically continuous rails through which electric propulsion return current flows and a train thereon having a speed control receiver means to receive a train speed control signal from said rails,

(a) a plurality of bonds interconnecting said rails and spaced along said rails, each of said bonds capable of equalizing the electric propulsion return current in said rails and having a primary coil and a secondary coil inductively coupled to said primary coil, said primary coil electrically connecting said rails, said bonds defining a plurality of track detection sections, each section having an entrance end and an exit end, said bonds serving as a signal transfer means to and from said rails,

(b) wayside transmitters electrically connected to a secondary winding of said bonds at alternate bonds,

(c) each Wayside transmitter having at least two wayside receivers tuned to the output of said wayside transmitters and each electrically connected to a secondary winding of the immediately adjacent bond,

(d) train speed control transmitter means electrically connected to the secondary Winding of each of said bonds,

(e) said wayside receivers controlling said train speed control transmitter means so that when said train enters said entrance end of a track detection section and shunts said rails, said train speed control transmitter means at said entrance end of said track detection section ceases to control said train and there is a simultaneous transfer of speed control to said train speed control transmitter means at said exit end of said track detection section.

24. A train speed control system for use in electrified territory, said system having electrically continuous rails through which electric propulsion return current flows and a train thereon having speed control receiver means to receive a train speed control signal from said rails,

(c) each wayside transmitter having at least two wayside receivers and related track relay means, said receivers tuned to the output of said wayside transmitters and each electrically connected to a secondary winding of the immediately adjacent bond, said wayside receivers controlling the actuation of said track relay means,

(d) train speed control transmitter means electrically connected to the secondary winding of each of said bonds and controlled by said track relay means,

(e) said wayside receivers controlling said train speed control transmitter means through said track relay 21 22 means so that when said train enters said entrance transmitter means at said exit end of said track deend of a track detection section and shunts said rails, tection section. said train speed control transmitter means at said entrance end of said track detection section ceases No references Citedto control said train and there is a simultaneous 5 transfer of speed control to said train speed control EUGENE BOTZ Pfimw'y Exami'le"

Claims

1. A TRAIN SPEED CONTROL SYSTEM FOR USE IN A SYSTEM HAVING ELECTRICALLY CONTINUOUS RAILS AND A TRAIN THEREON HAVING SPEED CONTROL RECEIVER MEANS TO RECEIVE A TRAIN SPEED CONTROL SIGNAL FROM SAID RAILS, (A) FIRST, SECOND AND THIRD BONDS INTERCONNECTING SAID RAILS, EACH BOND HAVING A TRAIN SPEED CONTROL TRANSMITTER MEANS ELECTRICALLY COUPLED TO SAID BOND TO PROVIDE TRAIN SPEED CONTROL SIGNALS TO SAID RAILS, AND SAID SECOND BOND HAVING A WAYSIDE TRANSMITTER ELECTRICALLY COUPLED TO SAID SECOND BOND, (B) SAID FIRST AND THIRD BONDS HAVING WAYSIDE RECEIVER TUNED TO THE OUTPUT OF SAID WAYSIDE TRANSMITTER AND ELECTRICALLY COUPLED THERETO TO CONTROL SAID TRAIN SPEED CONTROL TRANSMITTER MEANS SO THAT WHEN SAID TRAIN PASSES SAID FIRST BOND AND THEN SAID SECOND BOND, SAID TRAIN SPEED CONTROL TRANSMITTER MEANS AT SAID FIRST BOND AND SAID SECOND BOND RESPECTIVELY CEASE TO CONTROL SAID TRAIN AND THERE IS A SIMULTANEOUS TRANSFER OF SPEED CONTROL TO SAID TRAIN SPEED CONTROL TRANSMITTER MEANS AT SAID SECOND BOND AND THEN SAID THIRD BOND TO THEREBY PROVIDE A CONTINUOUS SPEED CONTROL TO SAID SPEED CONTROL RECEIVER ON SAID TRAIN.