US2286006A - Railway signaling system - Google Patents

Description

June 9, 1942. J. H; PELIKAN RAILWAY SIGNALING SYSTEM Filed June l5, 1940 Hfs' ATTORNEY Patented June 9, 1942 2,286,006 RAILWAY sIGNALING SYSTEM John M. Pelikan, Pittsburgh, Pa., assignor to The Union Switch & Signal Company, Swssvale, Pa., a corporation of Pennsylvania Application June 15, 1940, Serial No. 340,792

2 Claims.

My invention relates to railway traiic controlling apparatus, and more particularly to approach locking apparatus for use in interlocking systems for railroads to lock a track switch against operation under certain conditions when a signal governing movement of traffic over the switch is manually put to stop. The purpose of such locking is to prevent the operation of the switch when a train is approaching at such speed that it cannot be readily stopped without overrunning the signal,

Where a track stretch includes a track switch, as for example where there is a passing siding or a branch track, it is necessary to arrange the switch control mechanism so that the switch can be moved only when there are no moving trains in the vicinity of the switch, and to insure that before the switch is moved that the signals governing movement of trains across the switch are displaying stop indications, and also that a signal distant from the switch is conditioned to display a restrictive indication so that a train approaching the switch will be able to stop before reaching the switch.

It has heretofore been proposed to provide a line circuit controlled by track relays of an approach zone in the track stretch leading to the switch to detect Whether a train is approaching the switch. It has also been proposed to provide another line circuit leading from the distant signal to the control tower or other point from which the switch is controlled to indicate whether the distant signal is displaying a restrictive indication.

The approach zone of the track stretch which must be checked for occupancy is relatively long, while the distant signal which must be checked is located a considerable distance from the track switch. Accordingly the line circuits for checking the distant signal and occupancy of the approach zone of the track stretch are quite long and installation and maintenance of the wires for these line circuits involves considerable eX- pense. Obviously there would be a substantial saving if the same line circuit could be employed to check both the signal and occupancy of the approach zone.

It is an object of this invention to provide imy proved equipment of the type described which employs but a single line circuit to indicate atv a remote point the condition of a signal and of a stretch of railway track.

A further object of the invention is to provide improved means employing a single line circuit CnA . -the novel features thereof in claims.

to indicate at a remote point the condition of a In the drawing Fig 1 is a diagram showing a stretch of railway track equipped with apparatus embodying my invention, and

Fig. 2 is a fragmentary view showing a modied form of apparatus which I may employ in the system shown in Fig. 1.

Referring to the drawing, there is shown therein a stretch of railway track having a main track A and a siding or diverging track B which .is connected with the main track by means of a switch W. The switch W is operated between its normal and reverse positions by a switch machine SM which may be of any suitable construction well-known in the art.

The main track A has track rails I and 2 which are divided by insulated joints 3 into the usual track sections, which are identified as sections I 0T and IIT which together constitute an approach zone, while a detector section 12T is provided and includes the switch W and the portions of the tracks A and B adjacent thereto.

Each of the track sections is provided with track circuit apparatus which may be of any well-known type. As shown each section has a track battery TB connected across the section rails adjacent one end of the section, and a track relay TR having a winding connected across the section rails adjacent the other end of the section.

The main track A is provided with wayside signals which govern movement of trains through the track stretch. Only the signals governing movement of trains from left to right have been shown, but it should be understood that other signals may be provided to govern movement of trains from right to left if movement of trains in this direction is contemplated.

The wayside signals may be of any suitable type and are here shown as being of the color Iight type.

The home signal at the switch W has an upper track A across the switch W to the side or branch track B,

The signal SA has a green or clear lamp, a yellow or caution lamp, and a red or stop lamp, while the signal SB has a yellow or proceed lamp and a red or stop lamp.

A distance signal SD is located some distance from the switch W, this distance being such that trains traversing the track stretch and receiving a restrictive indication at the signal SD will be able to stop before reaching the switch.

The signal SD has a green or clear lamp, a yellow or caution lamp, and a red or stop lamp.

The distant signal SD is controlled in any desired manner by traiiic conditions in advance of the signal so that the signal will display its red or stop indication when a train is present in the track section HT. The signal SD is also controlled in accordance with the indication displayed b-y the home signal SA, so that when the home signal is displaying its red or stop indication the signal SD will display its yellow or caution indication.

The means by which the signal SD, is controlled in accordance with traiiic conditions in advance, and by the indications displayed by the signal SA is old and well-known in the art and has not been shown in order to simplify the disclosure.

Similarly, the signal SA is controlled by trafc conditions in advance of the signal, while manually operated means is provided for at times conditioning the signals SA and SB to display their red or stop indications, or to display proceed indications. The means by which this control of the signals is effected is old and wellknown in the art and has not been shown in order to simplify the disclosure.

A polarized switch control relay WR, controls the switch machine SM in the usual manner, while the supply of energy of normal or reverse polarity to the winding of the relay WR may be controlled in any manner well-known in the art.

The circuit of the winding of the switch control relay WR is controlled by an approach locking relay H, and by the track relay IZTR for the detector section I2T. The circuit of the approach locking relay l-I is controlled by the relay G, and also by relay J, by a contact of the relay H, by the track relay IZTR, and by a contact of a time release device, as hereinafter explained in detail.

A pair of line wires 20 and 2| coextensive with the section IIT are provided, while energy is supplied over these wires for at times energizing the relays G and J. The means for supplying energy to the line wires comprises a coding device CT which has contacts 24 and 25 which are continuously actuated between released and picked-up positions by a motor or other suitable means. The contacts 24 and 25 control the circuits for supplying energy from a battery 26 to the line wires, and are arranged so that when these contacts are picked up a circuit is established through which energy of one relative polarity, which may be considered to beof normal relative polarity, may be supplied to the line wires. When the contacts 24 and 25 are released a circuit is establishedv through which energy of the opposite or re- Ashunting the relay winding.

verse polarity may be supplied from the battery 25 to the line wires 20 and 2|.

The circuit for supplying energy of normal relative polarity to the line wires is controlled by contacts of the track relays IOTR and HTR so that the circuit is complete only when both of these relays are picked up.

The circuit for supplying energy of reverse relative polarity is controlled by contacts 29 and 39 which are governed in accordance with the indication displayed by the distant signal SD. The contacts 29 and 30 are controlled in such manner that they are picked up or closed when and only when the signal SD is displaying its stop or caution indication, and are released or open when the signal SD is displaying its clear indication.

Similarly, the circuit for supplying energy from the line wires 20 and 2l to the winding of the relay G is controlled by a contact 34 which is governed in accordance with the indications displayed by the home signals SA and SB in such manner that the contact is picked up when and only when the signals SA and SB are both displaying stop indications, and is released when either of these signals is displaying a proceed indication.

The relays G and J are of the type employing a permanent magnet to maintain the relay contacts in their released positions, and are arranged so that the relay contacts pick up only when energy of a particular polarity is supplied to the relay winding. A relay of the type which I may employ is shown in Letters Patent of the United States No. 1,959,562, issued May 22, 1934, to Harry E. Ashworth. The relays G and J are connected with the line wires so that the contact of the relay J picks up only when impulses of energy of normal relative polarity are supplied to the line wires, and so that the contact of the relay G picks up only when impulses of energy of reverse relative polarity are supplied to the line wires.

The relays G and J ",each have associated therewith a rectier which controls a circuit The rectier associated with each relay is connected in such manner as to prevent ow of energy through the shunt circuit of the polarity intended to pick up the relay contact and to permit flow of energy of the opposite relative polarity. The arrangement of the rectiers is such, therefore, that the winding of each relay is supplied with energy only of the polarity eective to pick up the relay contacts. As the relays G and J are of a type the contacts of which pick up only when energy of a particular polarity is supplied to the relay winding, there is no possibility that the contacts of either of these relays will pick up if the shunt circuit for the relay is interrupted so that energy of the polarity other than that intended for the relay flows in the relay winding.

When the signal controlled contact 34 is released, it not only interrupts the circuit of the winding of the relay G, but it also establishes a circuit shunting the winding of the relay G so that energy may be supplied to the winding of the relay J. The circuit established in the released position of the contact 34 has a rectier 35 in series therewith and arranged to permit flow of energy of the polarity eiective to pick up the relay J and to prevent ilow of energy oi the opposite polarity. Y

The equipment is shown in the condition which it assumes when there are no trains in the track stretch in the vicinity of the switch W, when the switch W is in its normal position, and the signal SA is conditioned to display its `red or stop indication and the signal SD is displaying its yellow or caution indication.

As it is assumed that the track stretch is vacant the track relays IUTR, I ITR and |2TR are energized by eurent supplied over the rails of the various track sections from the track batteries for these sections. As the track relays IUTR and l ITR are picked up impulses of energy of normal relative polarity are supplied over the line wires during the picked-up periods of contacts 24 and 25 of the coding device CT to energize the relay J and the contact 39 of this relay is picked up.

The circuit for supplying energy to the winding of the relay J is traced from terminal B of the battery 26 through front contact 25 of the coding device CT, contact 3| of track relay |0TR, Contact 32 of track relay ITR, line wire 2 l, front contact of the signal controlled contact 34, rectifier 45, winding of relay J, wire 20, contact 36 of track relay ||TR, contact 38 of track relay |TR, and front contact 24 of the coding device CT to terminal C of the battery 26.

The circuit for supplying energy to the windingr of the relay J is interrupted on movement of the contacts 24 and 25 of the coding device CT to their released positions. However, the relay J is rendered slow in releasing by the rectiiier which is connected across the terminals of the relay winding, and, accordingly, the contact of this relay remains picked up during the intervals between the supply of impulses of energy to the relay winding.

On movement of the contacts 24 and 25 of the coding device CT to their released positions they engage their back points of contact, and energy of reverse relative polarity is supplied to the line wires as the signal controlled contacts 29 and 30 are picked up.

As pointed out above, the contacts 29 and 3|] are governed in accordance with the aspect displayed by the distant signal SD in such manner that these contacts are picked up or closed when and only when the signal SD is displaying either its stop or its caution indication. As the signal SD is assumed to be displaying its caution indif cation the contacts 29 and 30 are picked up and impulses of energy of reverse relative polarity are supplied to the line wires 20 and 2|.

In addition, as the signal SA is assumed to be displaying its stop indication the contact 34 is picked up and interrupts the circuit of relay G. Accordingly, the circuit for supplying impulses of energy of reverse relative polarity to the relay G is complete and is traced from terminal B of the battery 26 through back contact 25 of the coding device CT, front contact 3U, line wire 20, rectier 46 associated with relay J, winding of relay G, front contact 34, line wire 2 I, front contact 29, and back contact 24 of the coding device CT to terminal C of the battery 26.

It will be seen, therefore, that when the signal SD displays its caution indication the circuit for supplying impulses of energy of reverse relative polarity to the line Wires 2|) and 2| is complete, and that if the approach section remains unoccupied impulses of energy of normal relative polarity continue to be supplied to the line wires. In addition it will be seen that when the home signals SA and SB are both conditioned to display stop indications a circuit is established to supply impulses of energy of reverse relative polarity from the line wires 20 and 2| to the relay G, while the circuit for supplying impulses of energy of normal relative polarity of the relay J is maintained.

Accordingly, at this time the contact 39 of the relay J is picked up, while contact 40 of relay G is also picked up and the pick-up circuit for supplying energy to the approach locking relay H is complete. The circuit is traced from terminal B of a local source of direct current, not shown, through front contact 40 of relay G, front contact 39 of relay J, and winding of relay H to terminal C of the source of current.

When relay H is picked up contact 48 establishes a stick circuit to maintain the relay picked up as long as contact 40 of relay G remains picked up.

In addition, when the approach locking relay H is picked up the circuit of the switch control relay WR is established, and the operator may move the switch W to the reverse position by moving the switch control lever L to its reverse position to change the polarity of the current supplied to the relay WR.

When the switch W attains its reverse position the operator may condition the signal SB to display its proceed indication, and when this is done contact 34 becomes released and interrupts the circuit for supplying energy to the relay G and establishes a circuit including the rectifier 35 for energizing the relay J.

Release of relay G releases the approach locking relay H, while release of the relay H interrupts the stick circuit for the relay, and in addition, interrupts the circuit of the switch control relay WR to prevent movement of the switch W.

The system provided by this invention is arranged so that if a train enters the approach zone at a time when one of the home signals is displaying a proceed indication, or the distant signal is displaying its clear indication, the switch W will be locked, and cannot be moved except as hereinafter explained in detail.

When the distant signal SD is displaying its clear indication the contacts 29 and 30 are released so that impulses of energy of reverse relative polarity are not supplied to the line wires 20 and 2|, while when either one of the home signals is displaying a proceed indication the contact 34 is released and interrupts the circuit of the relay G so that the contact 40 of the relay is released and interrupts the circuit of the approach locking relay H so that the contacts 42 and 43 of the relay H are released and interrupt the circuit of the switch control relay WR to prevent a change in the position of the switch W.

On entrance of a train into the section IUT the track relay |0TR. releases and interrupts the circuit for supplying impulses of energy of normal relative polarity to the line wires 20 and 2|. Accordingly, energy is no longer supplied to the relay J and the contact 39 of relay J releases. When the train advances into section HTthe track relay II'I'R releases and additionally intere rupts the circuit for supplying energy of normal relative polarity to the line wires.

From the foregoing it will be seen that when a train enters the approach zone the supply of energy t0 pick up the relay J is cut 01T with the result that the contact 39 becomes released to interrupt the pick-up circuit for the approach locking relay H. The supply of energy to the relay J continues to be interrupted until the train vacates section I IT, and therefore the contact 39 of relay J remains released as long as the train is present in the approach zone.

Accordingly, if after the train enters the approach zone the operator places the home signals at stop so the Contact 34 becomes picked up and establishes the circuit of the winding of the relay G with resultant picking up of the contact 4t! of this relay, the circuit of the approach locking relay H will not be established because contact 39 of relay J is released.

As the pick-up circuit of the relay H is not established this relay remains released and interrupts the circuit of the switch control relay WR to thereby prevent a change in the position of the switch W. This is desirable as the train having received a clear indication at signal SD may be traveling too fast to stop before reaching the switch W.

The system provided by this invention is arranged, however, so that after a train enters the approach zone the operator may change the position of the switch W, but only after the eX- piration of a predetermined time interval subsequent to the time at which the home signals are caused to display their stop indications. This time interval is long enough to permit a train to stop before reaching the switch W, or to advance into the detector section I2T and thus release the track relay IZTR to thereby prevent a change in the position of the switch W.

As pointed out above when a train enters the approach Zone the track relay IUTR releases and interrupts the supply of energy to the relay J so that the contact 39 of the relay J releases. If the home signals are now both caused to display stop indications the contact 34 will pick up, while when the distant signal SD becomes conditioned to display a restrictive indication the contacts 29 and 30 will pick up with the result that energy is supplied to the relay G and the contact 40 of this relay picks up. At this time, however, as contact 39 of relay J is released, the pick-up circuit of the approach locking relay H is not complete and the relay H remains released and continues to interrupt the circuit of the switch control relay WR.

The operator may now establish a pick-up circuit for the approach locking relay H by operating a time element device, not shown, which controls a normally open contact 62. This device may be of any suitable design well-known in the art, as for example that shown in Letters Patent of the United States No. 2,114,895 to Harry E. Ashworth, and is arranged so that the contact 62 becomes closed only after the expiration of a predetermined time interval after operation of the device is initiated. When contact 62 closes a circuit including contact 40 of relay G and the contact 62 is established to pick up the approach locking relay H.

When relay H picks up its contact 48 establishes a stick circuit to maintain the relay picked up as long as relay G is maintained picked up, while on picking up of relay H the circuit of the switch control relay WR is established, assuming that the train which had entered the approach zone was able to stop before entering the detector section |2T. On establishment of the circuit of the switch control relay WR the operator may move the switch W by changing the polarity of the current supplied to the relay WR, as eX- plained above.

When the switch W completes its movement the operator may condition the appropriate one of the home signals to display a proceed indication. When this is done contact 34 becomes released and interrupts the circuit for supplying energy -to the relay G, and contact 40 becomes released to interrupt the circuit of the approach locking relay H. Accordingly, the relay H releases and contact 48 interrupts the holding circuit for the relay winding, while contacts 42 and 43 interrupt the circuit of the switch control relay to prevent further changes in the position of the switch.

From the foregoing it will be seen that the system provided by this invention provides means requiring but a single line circuit to constantly check the condition of the home and distant signals and of occupancy of an approach zone of track. It will be seen also that each of these conditions is checked independently of the other with the result that each may be determined irrespective of the other.

The condition of track occupancy is checked by the supply of impulses of energy of one relative polarity to the line circuit, while the supply of these impulses is controlled by the track relays of the approach zone in such manner that the supply of these impulses is entirely independent oi the condition of the signals.

Similarly, the condition of the distant signal is checked by the supply of impulses of energy of the other or reverse relative polarity to the line circuit, and the supply of these impulses of energy is entirely independent of the condition of occupancy of the approach zone. Likewise, the condition of the home signals is checked by the supply of energy of reverse relative polarity from the line circuit to the relay G, while the supply of energy to the relay G is independent of the condition of occupancy of the track stretch.

In addition, the system is arranged so that impulses of energy of normal relative polarity may be supplied from the line circuit to the relay J regardless of the position of the signal controlled contact 3d.

It will be seen also that when the signal controlled contact 34 is in its released position and cuts off the supply of energy to the relay G, the circuit which is established to permit the supply of energy to the relay J includes a rectifier 35 in series therewith. The rectier 35 permits flow of current of the polarity effective to pick up the relay J, but prevents low of current of the opposite relative polarity in this circuit. This is advantageous as it prevents short circuiting of the battery 26 if impulses of energy of reverse relative polarity are supplied to the line circuit when the contact 34 is released.

The system shown in Fig. l of the drawing employs a coding device CT to provide the alternate impulses of normal and reverse relative polarity. However, the invention is not limited to the use of this device, and if alternating current is available this may be employed, and Fig. 2 is a'fragmentary View showing this modification.

Except as hereinafter specically pointed out in detail the modification shown in Fig. 2 is the same as that shown in Fig. l, and the same reference characters are employed to identify the elements common to both iigures.

In the modiiication shown in Fig. 2 a transformer TT is provided and has its primary winding supplied with energy from a source of alternating current, the terminals of which are designated BX and CX.

One terminal of the secondary winding of the transformer TT is connected with contact 38 of the track relay IDTR, while the other terminal of the transformer secondary winding is connected to contact 3| of the track relay IDTR. The circuits for connecting the transformer with the contacts of the track relay include in series therewith asymmetric or rectifier units and 1I which are arranged to permit energy of normal relative polarity to be supplied vto the line wires 2U and 2| and to prevent the supply of energy of the other or reverse relative polarity to the line wires.

In addition, one terminal of the transformer secondary winding is connected with the signal controlled contact 29 and the other terminal of the transformer secondary winding is connected with the signal controlled contact 30. The circuits for connecting the transformer secondary winding with the signal controlled contacts include in series therewith asymmetric or rectier units 13 and `I4 which are arranged to permit energy of reverse relative polarity to be supplied to the line wires 2U and 2| and to prevent the supply of energy of the other relative polarity.

In operation, on the supply of alternating current energy to the primary winding of the transformer TT impulses of energy of opposite relative polarity are alternately induced in the secondary winding of the transformer. If the contacts of the track relays ITR and IITR are picked up impulses of energy of one or normal relative polarity induced in the transformer secondary winding are supplied to the line circuit through the rectier units 1U and 1| and the track relay contacts.

Similarly, when the signal controlled contacts 29 and 3U are picked up impulses of energy of reverse relative polarity are supplied from the transformer to the line circuit through the rectifier units 13 and 14 and the signal controlled contacts. l

Accordingly, if the signal controlled contacts and the track relay contacts are both closed irnpulses of energy of each polarity will be supplied to the line circuit, the impulses of either polarity occurring during the off periods between the supply of impulses of the other relative polarity.

Although I have herein shown and described only one form of railway signaling system embodying my invention, together with one modification thereof which I may employ, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track containing a switch movable between a normal and a reverse position, an approach track zone, a distant signal governing movement of traic through said approach Zone towards said switch, said distant signal being capable of displaying a clear indication and at least one restrictive indication, a home signal governing movement of trains across said switch, said home signal being capable of displaying a stop indication and at least one proceed indication, a pair of line conductors, means governed by said distant signal and operative only when said signal is displaying a restrictive indication to establish reverse supply connections to supply energy of reverse relative polarity to said line conductors, means governed by traiiic conditions in said approach zone CTI and operative only when said zone is vacant to establish normal supply connections to supply energy of normal relative polarity to said line conductors, means for alternately supplying iinpulses of energy to said normal and reverse supply connections, an approach locking relay operative when deenergized to prevent movement of said switch, a first and a second control relay each having a Winding included in series with the circuit of said line conductors, each of said control relays having an asymmetric unit connected across the relay winding to render the relay responsive to energy of one polarity only and to also render the relay slow to release, the unit associated with the first control relay being arranged so that said relay is responsive to energy of reverse relative polarity only and the unit associated with the second control relay being arranged so that said relay is responsive to energy of normal polarity only, a contact movable between a iirst and a second position, said contact being governed in accordance with the indication displayed by said home signal and occupying said rst position when and only when said home signal is displaying its stop indication, said contact being operable when occupying said first position to establish the circuit for connecting the winding of the iirst control relay in series with said line conductors, said contact being operable when occupying said second position to interrupt the circuit for connecting the winding of the first control relay in series with the line conductors and to connect the line conductors in series with an asymmetric unit arranged to permit energy of normal polarity only to iiow in said line conductors, whereby when said contact occupies said second position energy of normal polarity may flow in the circuit of said line conductors and energize said second control relay but ilow of energy of reverse relative polarity and resultant short circuiting of the source from which energy is supplied to said line conductors is prevented, a circuit complete when the contacts of both of said control relays are picked up to energize said approach locking relay, and a circuit for also energizing the approach locking relay when the contacts of the second control relay are released provided the contacts of the rst control relay are picked up.

2. In combination, a stretch of railway track containing a switch movable between a normal and a reverse position, an approach track zone, a distant signal governing movement of traffic through said approach zone towards said switch, said distant signal being capable of displaying a clear indication and at least one restrictive indication, a home signal governing movement of trains across said switch, said home signal being capable of displaying a stop indication and at least one proceed indication, a pair of line conductors, means governed by said distant signal and operative only when said signal is displaying a restrictive indication to establish reverse supply connections to supply energy of reverse relative polarity to said line conductors, means governed by traiiic conditions in said approach Zone and operative only when said zone is vacant to establish normal supply connections to supply energy of normal relative polarity to said line conductors, means for alternately supplying impulses of energy to said normal and reverse supply connections, an approach locking relay operative when deenergized to prevent movement of said switch, acontact movable between a first and a second position, said contact being governed in accordance with the indication displayed by said home signal and occupying said first position when and only when said home signal is displaying its stop indication, a rst and a second control relay, the second control relay having a winding connected in series with said line conductors and also in series with asymmetric means arranged to permit energy of normal. polarity only to flow in said line conductors regardless of the position of said signal controlled contact, an asymmetric. unit connected across the terminals of the second control relay, said unit being arranged to permit energy of reverse relative polarity to flow therethrough, whereby regardless of the position occupied` by said signal controlled Contact energy of normal polarity supplied to said line conductors flows, through said asymmetric means and energizes said second control relay, said. signal controlled contact being effective when occupying its first position to connect the Winding of said first control relay in multiple with said asymmetric means whereby when said signal controlled contact occupies its rst position energy of reverse polarity supplied to said line conductors flows through the asymmetric unit associated with said second control relay and energizes the rst control relay, but when said signal controlled contact occupies its second position the circuit of said rst control relay is interrupted and said asymmetric means prevents flow of energy of reverse polarity in saidv line conductors and resultant short circuiting of the source from which energy is supplied to said line conductors, a circuit complete when the contacts of both of said control relays are picked up to energize said approach locking relay, and a circuit for also energizing the approach relay when the contacts of the second control relay are released provided the contacts of the first control relay are picked up.

JOHN M. PELIKAN.

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