US2448570A

US2448570A - Trap circuit control for railway signals

Info

Publication number: US2448570A
Application number: US739569A
Authority: US
Inventors: Earl M Allen
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1947-04-05
Filing date: 1947-04-05
Publication date: 1948-09-07
Anticipated expiration: 1965-09-07

Description

Sept. 7, 1948. E. M. ALLEN TRAP CIRCUIT CONTROL FOR RAILWAY SIGNALS Filed April 5, 1947 WA, m T P. A MN mm Nm QN QN M w QW* 3f m] w @mi 5j QT. QN. No, w m m N E u m mum@ REN, 93 n e awww ma 5N. r, wij@ Q m@ NSW N\\ N Nm, N .b

Patented Sept. 7, `1 948 TRAP CIRCUIT CONTROL FOR RAILWAY SIGNALS Earl M. Allen, Pittsburgh, Pa., assigner to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application April 5, 1947, Serial No. 739,569

6 Claims.

My invention relates to trap circuit control for railway signals, and particularly to an arrangement of circuits for providing continuous control of railway signals by a train on a stretch of track which includes a dead section in an otherwise continuous series of track circuited sections.

In some situations such, for example, as where one railway crosses another railway which has a plurality of tracks, the rst railway has a section through the multiple track crossing which cannot be provided with a track circuit and which is longer than the shortest train which may be run on the first railway. It is therefore possible for a short train to occupy this section, known as a dead section, at the crossing, without shunting any track circuit. In such a situation, it is common practice to use an arrangement of circuits to provide what is known as trap circuit control, through which a signal for the first railway is controlled by a train on the rst railway approaching the crossing to indicate stop when the train passes the signal, and to continuously indicate stop while the train is wholly on the dead section and until the train has passed through the first section beyond the dead section.

One feature of my invention is the provision of a directional trap circuit arrangement, in which a trap circuit stick relay, which becomes deenergized when a train moves from an approach section wholly onto a dead section, can again become energized only in response to the train passing from the dead section into an adjacent approach section and cannot become energized by a second train entering the opposite end of van adjacent approach section.

Another feature of my invention is the provision of circuits for controlling a trap circuit stick relay arranged so that the trap circuit stick relay will become deenergized by only a train that is short enough to be wholly on lthe dead section. A train that is long lenough that, all the While it is passing over the dead section, it extends over onto one of the adjacent sections, will not deenergize the trap circuit stick relay.

I shall describe one form of apparatus em-` bodying my invention, and shall then point out the novel features thereof in claims.

TheL accompanying drawing is a diagrammatic View showing one form of apparatus embodying my invention, in which each of the two Vtrack sections adjoining the ends of a dead section is provided with a track circuit including a track relay connected across its end which adjoins the dead section, and also including a second track relay connected around an insulatedfjoint in one of its rails; and in which directional control oi a trap circuit stick relay is effected by these track relays and by a slow pick-up and slow release relay for each track circuit controlled by its track relays.

Similar reference characters refer to similar parts in the drawing.

Referring to the drawing, a single track railway is shown crossing a multiple track railway designated by the reference character L. Rails i and la ci the single track railway are divided by insulated joints 2 to form a section a-b adjoining one end of a dead section b-c, and a second section c-d adjoining the opposite end of dead section b-c. The rail of one side of each of the sections a-b and c--d is also ldi vided by anY insulated joint 3 to form subsections 5T and AST of section (L -b, and subsections ET and AST of section c-d.

Section a-b is provided with a track circuit including a track relay A5R connected across the end of section a-`b which is adjacent one end of the dead section o o, and including a suitable source of current such as a battery 4- connected across the opposite end of the section, and also including a second track relay 5R connected around its insulated joint 3. Section c-d is provided with a similar track circuit including a track relay ABR connected across the end of section c-d Vwhich is adjacent the opposite end of the dead section bc, and including a battery 4 connected across the opposite end of the section, and also including a second track relay 6R connected around its insulated joint 3. Asignal, designated by the reference charac--v ter 5S,'is located adjacent the battery end of sectiona-b for governing traflic movements towards the right, as shown in the drawing, which I shall assume is the eastbound direction. A second signal SS is located' adjacent the battery end of section c-'d for governing traiiic movements in the opposite or westbound direction. Signals 5S and GS may be of any suitable design such, for example, as the Well-known searchlight type. l

A slow pick-up and slow release relay, designated by the reference character 5P, is controlled by relays A5R and 5R. A second slow pick-up and slow release relay 6P is similarly controlled by relays ASR and 6R. 1

A trap circuit stick relay, designated by the reference character TPS, is controlled by the track relays and by the slow pick-up and slow release relays. An impedance is connected ln multiple with the winding of relay TPS in order to make this relay slow in releasing.

Having described, in general, the arrangement of the various parts ci apparatus embodying my invention, I shall now describe the circuits and operation in detail.

As shown in the drawing, all parts of the apparatus are in the normal condition, that is, the track sections are unoccupied, and therefore track relays SR, ASR, ASR and 6R aire energized; relays SP, SP and TPS are also energized; and signals SS and SS are displaying a proceed indication.

The circuit by which relay 5P is energized passes from terminal B of a suitable source of current, through the front point of contact I of relay ASR, and the winding of relay SP to terminal N of the same source of current. Relay 6P is energized by a similar circuit passing from terminal B, through the front point of contact I of relay ASR, and the winding of relay 6P to terminal N.

Relay TPS is energized by a stick circuit passing from terminal B, through the front point of contact 9 of relay ASR, contact I of relay 6P, front point of contact II of relay ASR, contact I2 of relay SP, Contact I3 of relay TPS, and the winding of relay TPS in multiple with impedance 1 to terminal N.

The circuit by which signal SS is controlled to display a proceed indication includes contacts I4, IS, I6, I'I and I8 of relays SR, ASR, ASR, SR and TPS, respectively, and the mechanism of signal SS to terminal N. The circuit by Which signal SS is controlled to display a proceed indication includes contacts I9, 20, 2l, 22 and 23 of relays TPS, SR, ASR, ABR and 6R, respectively, and the mechanism of signal GS to terminal N.

I shall assume that an eastbound train which is shorter than dead section b-c approaches signal SS. This train, upon entering section a--b, deenergizes relays SR and ASR. Relay ASR, upon becoming deenergized, opens, at the front point of its contact 'I, the circuit previously traced for energizing relay SP. A second circuit is now completed for energizing relay SP, however, passing from terminal B, through the back point of contact 'I of relay ASR, back point of contact 8 of relay SR, and the winding of relay SP to terminal N. Relay SP, on account of being slow releasing, does not permit its contact I2 to open during the interval between the opening of the iirst circuit and the closing of the second circuit for energizing this relay.

Relay ASR, upon becoming deenergized, opens, at the front point of its contact I I, the stick circuit previously traced for relay TPS, and then closes, at the back point of its contact II, a second stick circuit for relay TPS passing from terminal B, through the front point of contact 9 of relay ASR, contact I0 of relay SP, back point of `contact II of relay ASR, contact I3 of relay TPS, and the winding of relay TPS in multiple with impedance r to terminal N. Relay TPS, on account of being slow releasing, does not permit its front contacts to open during the interval between the opening of the front point of contact II of relay ASR and the closing of the back point of this contact.

With relays ASR and SR deenergized, the circuit for signal SS is now open at contacts I6 and I1, respectively, causing signal SS to display the stop indication. Likewise, contacts 20 and 2IA of relays VSR and ASR, respectively, are open in the 4 circuit for controlling signal BS, and therefore the arm of signal SS will now also display the stop indication.

When the rear end of the train passes insulated joint 3 of section a-b, relay SR becomes energized, thereby completing a pick-up circuit for relay TPS, this circuit passing from terminal B, through the back point of contact 'I of relay ASR, iront point of contact 8 of relay SR, and the winding of relay TPS in `multiple with impedance r to terminal N. Relay SR, upon becoming energized, opens, at the back point of its contact 8, the second circuit traced for energizing relay 5P, and, therefore, relay SP becomes deenergized.

When the rear end of the train leaves section a-b, relay ASR again becomes energized, thereby opening, at the back point of its contact 'I, the pick-up circuit previously traced for relay TPS and opening, at the back point of its contact I I, the second stick circuit traced for relay TPS. Relay SP is now again energized by the circuit iirst traced for this relay through the front point of contact 'I of relay ASR. On account of relay SP being slow to pick up, the front contacts of relay TPS will open between the time of the opening of contact I I of relay ASR at its back point and the closing of contact I2 of relay SP. With relay TPS noW deenergized, the circuits for signals SS and SS remain open at contacts I8 and I9, respectively, of this relay while the train is entirely on dead section b-c.

When the front end of the train enters subsection AST, relay ASR becomes deenergized, thereby opening, at the front point of its contact 1, the circuit previously traced for relay SP, causing relay 6P to become deenergized, With relay AGR deenergized, a second pick-up circuit is now completed for relay TPS, this circuit passing from terminal B, through the back point of contact 'I of relay ASR, front point `of contact 8 of relay 6R, and the winding of relay TPS and impedance r to terminal N. A third stick circuit is now completed for relay TPS, this circuit passing from terminal B, through the back point of contact 9 of relay ASR, contact I3 of relay TPS, and the winding of relay TPS and impedance 1 to terminal N. With relay ASR deenergized, the circuits for signals SS and SS are now open at contacts IS and 22, respectively, of relay ASR.

When the front end of the train enters subsection ST, relay 6R becomes deenergized, thereby opening the second pick-up circuitr previously traced for relay TPS, which however now remains energized by its third stick circuit previously traced. A second circuit isV now completed for energizing relay 6P, this circuit passing from terminal B, through the back point of contact 'I of relay ASR, the back point of contact 8 of relay SR, and the winding of relay EP to terminal N. With relay BR deenergized, the circuits for signals SS and 6S are now open at contacts I4 and 23, respectively, of relay 6R as well as at contacts IS and 22 of relay ASR.

When the train leaves section c-d, relays ASR and 6R again become energized. The second circuit traced for energizing relay SP is thereby opened, and the first circuit traced for this relay is then again closed. The third stick circuit traced for relay TPS is opened at the back point of contact 9 of relay ASR, and the rst stick circuit traced for this relay is again closed through the iront point of contact 9 of relay AGR. With all track relays and relay TPS now energized, the portions of the circuits shown for controlling sigcausing relay 5P to become deenergi'zed. The' first pick-up circuit traced for relay TPS is now completed through the back point of contact 1 of relay ASR, and hence relay TPS becomes energized. The second stick circuit traced for relay TPS through the back point of contact I l of relay ASR is then also again closed.

When the rear end of the train enters subsection 5T, relay 5R becomes deenergized, thereby opening the first pick-up circuit traced for relay TPS which, however, remains energized by its second stick circuit. Relay 5P is now energized by its second circuit through the back points of contacts 1 and!! of relays AER and 5R, respectively.

When the train leaves section a-b, relays A5R and 5R again become energized, and relay 5P is now again energized by the circuit first traced for this relay through the front point of contact 'I of relay ABR.. The second stick circuit traced for relay TPS is now opened and the first stick circuit traced for this relay is again closed. With all track relays and relay TPS now energized, the portions of the circuits shown for signals 5S and GS are again closed and, therefore, all parts of the apparatus are again in the normal condition.

I shall again assume that a short eastbound train moves through section a-b, and that it stops wholly on section b-c, causing relay TPS to be de'energized, as previously described. I shall assume further that a following eastbound train, although attempting to stop in response to the stop indication displayed by signal 5S, actually does not succeed in getting stopped until its front en-d has entered subsection 5T. The first circuit traced for relay 5P will now be opened and its second circuit will be closed, Both the pick-up circuits previously traced for relay TPS remain open, and therefore relay TPS does not now become energized.

It follows that relay TPS, after being deenerglzed when a short train moves wholly onto section b--c, can again become energized only in response to a train moving from section b-c into section a-b or c-d, and not by a second train entering either section a-b or c-d from the opposite end.

I shall now assume that an eastbound train which is longer than dead section b--c moves through section a-b into section b-c. Since the train is longer than section b-c, its front end will enter section c-d before the rear end leaves section a-b. The second pick-up circuit for relay TPS is therefore closed while its front contacts are still closed by its second stick circuit or its first pick-up circuit, and hence relay TPS does not become deenergized. When the train leaves section a-b and continues through section c-d, the various parts of the apparatus operate as previously described when a short train moves through section c--d.

If, instead of proceeding through section c-d, the long train, after its front end has entered subsection AST, stops, and then backs past signal5S, relay TPS will continue energized'. After the train leaves section c-d, all parts of the apparatus will operate as previously described when a short train backs through section a-b.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modications 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 a control arrangement for a trap stick relay in a railway signal control system for a stretch of railway track divided into a rst and a second section and also a dead section between said first and second sections, the combination comprising, an insulated joint in one side of each of said flrst and second sections, a track circuit for each of said rst and second sections each including a track relay connected across the rails of the end of its section which is adjacent said dead section and including a source of current connected across the rails of the opposite end of its section and also including a second track relay connected around the said insulated joint in one side of its section, a first and a second pick-up circuit `for said trap stick relay one of which is controlled by a back contact of the first track relay and by a front contact of the second track relay for one of said track circuits and the other of which is similarly controlled by the track rclays fcr the other track circuit, a slow pick-up and slow release relay for each of said track cirn cuits each having an energizing circuit controlled by a front contact of the first track relay for its section and each also having a second energizing circuit controlled by back contacts of both' track relays for its section, a stick circuit for said trap stick relay controlled by front contacts of both said slow pick-up and slow release relays and by front contacts of both of said rst track relays,V

a second stick circuit for said trap stick relay controlled by a back contact of the first track relay for one of said sections, and a third stick circuit for said trap stick relay controlled by a back contact of the first track relay for the other section.

2. In a control arrangementl for a trap stick relay in a railway signal control system for a stretch of railway track divided into a first and a second section and also a dead section between sai-d rst and second sections, the combination comprising, an insulated joint in one side of each of said iirst and second sections, a track circuit for each of said first and second sections each including a track relay connected across the rails of the end of its section which is adjacent said dead section and including a source of current connected across the rails of the opposite end of its section and also including a second track relay connected around the said insulated joint in one side of its section, a slow pick-up and slows7 release relay for each of said track circuits, means for each track circuit controlled by a front contact of its iirst track relay or by back contacts of both its track relays for energizing its slow pick-up and slow release relay, means controlled by a train approaching said dead section through either said rst or said second section for retaining said trap stick relay energized, means controlled by the slofw pick-up and slow release relay for each track circuit for deenergizing said trap stick relay when a train passes from its section into said dead section. and means controlled by the iirst track relay 'for each of' said track circuits for again energizing said trap stick relay when a train enters its section from said dead section.

3. In a control rarrangement for a trap stick relay in a railway signal control system for a stretch of railway track divided into a first and a secon-d section and also a dead section between said rst and second sections, the combination comprising, an insulated joint in one side of each of said rst and second sections, a track circuit for each of said first and second sections each including a track relay connected across the rails of the end of its section which is adjacent said dead section and including a source of current connected across the rails of the opposite end of its'section and also including a second track relay connected around the said insulated joint in one side of its sec-tion, means controlled by the first track relay for each track circuit in response to a train in its section approaching said dead section for retaining said trap stick relay energized, means controlled by both track relays for each track circuit in response to a train moving from its section into said dead section for deenergizing said trap stick relay, and means controlled by both track relays for each track circuit in response to a train moving into its section from said dead section for `again energizing said trap stick relay.

4. In a control arrangement for a trap stick relay in a railway signal control system for a stretch of railway track divided into a rst and a second section and also a dead section between said first and second sections, the combination comprising, an insulated joint in one side of each of said rst and second sections, a track circuit for each of said first and second sections each includin-g a track relay connected across the rails of the end of its section which is adjacent said dead section and including a source of current connectedv across the rails of the opposite end of its section and also including a second track relay connected around the said insulated joint in one side of its section, and means controlled by said track relays for retaining said trap stick relay energized while a train is approaching said dead section and for deenergizing said trap4 stick relay when a train moves from either of said first and second sections into said dead section and also for again energizing said trap stick relay when a train moves from said dead section into either said first or said second section.

5. In a control arrangement for a trap stick relay in a railway signal control system for a stretch of railway track divided into a first and a second section and also a dead section between said rst and second sections, the combination comprising a track circuit for each of said first and second sections, means controlled by said track circuits in response to a train approaching said dead section for retaining said stick relay energized, means controlled by said track circuits in response to a train moving from said first or said second section into said dead section for deenergizing said trap stick relay, and means controlled by said track circuits in response to a train entering said iirst or said second section from said dead section for again energizing said trap stick relay.

6. In a control arrangement for a trap stick relay in a railway signal control system fora stretch of railway track divided into a first anda second section and also a dead section between said rst and second sections, the combination comprising, a slow ,pick-up and slow release relay for each of said first and second sections energized when the associated section is unoccupied, means responsive to a train in each of said rst and second sections approaching said dead section for retaining said trap stick relay energized, means responsive to a train in each of said rst and second sections approaching said dead section for at rst energizing and then deenergizlng the associated slow pick-up and slow release relay, means controlled by each of said slow pickup and slow release relays for deenergizing said trap stick relay when a train moves from the associated iirst or second section into said dead section, and means responsive to a train entering either of said iirst or second sections from said dead section for again energizing said trap stick relay.

EARL M. ALLEN.