US1792455A - Railway-traffic-controlling system - Google Patents

Description

Feb. 10, 1931. s. N. WIGHT RAILWAY TRAFFIC CONTROLLING SYSTEM Filed May 16, 192'? 2 Sheets-Sheet l Feb. 10, 1931. s. N. WIGHT RAILWAY TRAFFIC CONTROLLING SYSTEM Filed May 16, 1927 2 Sheets-Sheet 2 INVENTOfi/ ,3 BY 4 ATTORNEY Patented .Feb. 10, 1931 UNITED STATES" PATENT. OFFICE SEDGWICK N. WIGHT, OF ROCHESTER, NEW-YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK RAILWAY-TRAFFIC-CONTROLLING SYSTEM Application filed May 16,

This invention relates to a single track railway signaling system of the absolute-permissive-block type, and more particularly to apparatus and circuits for controlling the usual stick relay of such system when color light signals are used. 7 a a In an absolute-permissive-block signal system, such as disclosed for example, in my prior Patent No. 1,294,736, of February 18, 1919, the desired control of the block signals involves the use of a line or signal relay controlled by the track relays of two adjacent track circuits. Track relays in the usual normally closed direct current track circuits are 1.1 very slow dropping. This slow dropping characteristic is largely due, it is believed to the fact that such relays are dropped by being shunted by the passing train, and such shunt-, ing of their windings cause their windings to an act like bucking coils and causes them to oppose a change in the flux in their magnetic circuits. These same track relays, on the other hand, are rather quick in picking up when their respective track circuits are 2- cleared, because there is then no short CH: cuited coil opposing a chan e in the fla r oi the magnetic circuit thereoi From this t readily appears that if a line or home relay isjointly controlled through front contacts of the relay of two successive track circuits, the passage of a short train, such as an engine and tender running alone, from one section thereof into the next section may possibly cause the de-energized track relay to pick up 33 before the energized track relay drops, so that the line or home relay controlled by these track relays is momentarily picked up While such train moves from one track circuit upon the adjoining'track circuit. In an absolutepermissive-block signal system, as disclosed in detail in my prior patent above mentioned, a directional stick relay is controlled by a track relay and a slow-acting circuit controller governed by a signal or line relay. When semaphore signals are used, as shown the directiona 1927. Serial No. 191,735;

in my prior patent, the usual circuit controller operated by the semaphore signal mechanism" has the necessary operating characteristics of the slow-actin circuit controller governing Istick relay; but when color light signals are used, special provisions must be made to obtain such a slow-acting circuit controller. As shown in my prior application, Ser. No. 120,432 filed July 3, 1926, a slow releasing relay, governed by the line relay, may be employed to control the directional stick relay. Such a slow-releasing relay, however, while it can be readily designed to provide the required dela in the dropping of its armature upon its e-energization is relatively quick acting upon energization.

In View of the foregoing and other important considerations it is'proposed in accordance with the present invention to provide special means to delay the energization of such a slow-releasing rela in response to energization of the home re ay of a signal location of an absolute-permissive-block signal system, so that the momentary energization of such home relays will not cause the directional stick relay associated therewith to be picked up.

An electro-thermalresponsive relay has slow acting characteristics which makes it suitable for controlling contacts an interval of time after a certain circuit is closed, but such thermal responsive relay or device is rather ineflicient and therefore it is not very suitable for use-as a regular relay in a signaling system; and more especially it is therefore proposed to use a thermal device for picking up another relay of the stick type and to cause such another relay to cut theenergizing current off of the electro-thermal-responsive device, so that the feature of a time element delay is taken advantage of and the device need only be energized for a very short time sufficient to cause closure of its contacts, that is, its efliciency is not important when used in this Way,

Other objects, purposes and characteristic features of the present invention will in part bepointed out hereinafter, and in part be obvious from the drawings.

In describing the invention in detail, reference will be made to the accompanying drawings, in which Fig. 1 shows conventionally the apparatus at a signal location of an absolute-permissive-block signal system employing my invention; and

Fig. 2 conventionally illustrates similar apparatus employing a modified form of my invention.

Structure F z'g. 1.-In order to simplify the description of the present invention only the control circuits and apparatus of a single signal location of an absolute-permissiveblock signal system has been sli'dwn. Referring to Fig. l of the drawings, there are shown three condition stop-andstay light signals 1 and 2 at the end of a passing siding, containing a track switch S1, of which the signal 2 is a starting signal and the signal 1 a leaving signal for a signal track section. Two intermediate permissive three condition light signals 3 and 4 also have been shown. The stop-and-stay signals 1 and 2 are distinguishable from the permissive signals 3 and 4 by having the marker light M directly in line with the green, yellow and red lights, G, Y and B respectively of the light signal units thereof; whereas the marker light M of the permissive signals 3 and 4 is set off to the right or to the left of the signals G. Y and R thereof. Of the single track section shown, the block between the signals 1 and 3 is di- Vided into two sections. but may. if desired, have more or less than two sections, depending on local conditions, each section of which is provided with the usual closed track circuit including a battery B and a suitable track relay. The track relays for these cut sections have been conventionally shown by dotted lines and are designated QT and ST, respectively.

The control relays and circuits for the sig nal 3 only have been shown, of which the home relay 3H is directly controlled by the track relays QT and 3T through a circuit as follows :beginning at a terminal I3 (-lor which is plus if the signal 1 is clear or caution and is minus when the signal 1 is at stop, front contact 11 of the track relay 2T, wire 12-, front contact 13 of the track relay 3T, wire 14:, winding of the home relay 3H, to the common return wire 0 connected to the midpoint of said battery. This home relay 3H through its front contact 15 may apply current to the winding of the thermal relay Til if the pole changer relay 31 C is to be energized. Normally this home relay 3H through its front contact 15 maintains the pole changer relay 31 C energized through the following stick circuit :-beginning at the terminal B+, front contact 15 of the home relay 3H, wire 16, winding of the pole changer 3PC, wires 17 and 18, front stick contact 19 of the pole changer relay 31 C, to the terminal 13-. The home relay 3H is a polar neutral relay of the usual construction, and this home relay in conjunction with the slow dropping pole changer relay 3P0 controls the indicating condition-of the light signal-3 through circuits which have been shown by dotted lines and are well understood by those skilled in this art. The signal apparatus in question also includes the usual directional stick relay 3S the function of which is understood by those skilled in the art of single track railway signaling.

Operation Fig. 1.In order to get a clear understanding of the advance in the art contributed by the present invention, it is '-be lieved expedient to first consider the movement of a train from right to left by the signal 3 in which case the relays 3H, Z-BPC-and.

3S, change from their normal to their abnormal condition, and in which case the function of the slow acting electro-thermal-responsive relay does not come into play except as to its regularfunction of picking up the pole changer relay, and thereafter consider the movement of a short train, such as an engine and tender running alone moving from left to right, in which case the functioning of the thermal relay comes into play and in connection with which train movement the weakness of a system not employing a means for de laying the closure of certain contacts of the pole changer relay 3P6 may be more definitely pointed out. It may be pointed out at this time that the function of the stick relay 38 in an absolutc-permissive-block sys tem is to shunt the front contact 20 of the relay SPC, which contact is contained in the line circuit 21 of the home relay for the next signal in the rear, so that said home relay in the rear may be energized in spite of deenclgization of the pole changer relay SPC the signal in question, provided the train which passed was moving from right to left and picked up this stick relay, all of which is well known by those skilled in the art of A. P. B. signaling.

Let us now consider the movement of a train from right to left by signal 3. As soon as this train passes the signal 3 the track relay 3T is de-energized which in turn de-energizes the home relay 3H. De-energization of the home relay 3H opens contact 15, and thereby causes de-energization of the pole changer relay 3PC. Since, however, the pole changer relay 31 C which, when direct current is used, in most instances comprises a relay having a ferrule or bucking coil thereon opposing a sudden change of flux in the relay magnetic structure, is slow in dropping, and for this reason keeps its contact 24 closed for some time after de-energization of its cuit causes the stick relay 3S to pick up and as soon as picked up is stuck up through the.

following circuit:-beginning at the terminal B+ front stick contact 30 of relay 3S,

wires 31 and 32, back contact 33 of the home relay 3H, wires34 and 26, winding of the relay 3S, wire 27 to the terminal B. After a short interval of delay there .is another stick circuit completed which is the same as the one just traced except that for the back contact 33 of the home relay 3H is substituted the back'contact 35 of the relay 3P0 and Wires 36 and 25, so that the stick relay 3S is stuck up so long as either the home relay 3H or the pole changer relay SPC are de-energized. This energization of the stick relay 3S permits another train to follow the-train in question with signal protection the same as is afforded in double tracksignaling, all without permitting an opposing train to enter the single track section in question, as well understood by those skilled in the art.

If this train continues its movement from right to left, assuming it to be a train of average length, the home relay 3H will remain deeenergizeduntil the train has completely passed the signal 1. If this train just considered, however, is a very short train, such as an engine and tender running alone, and it moves at a rather high speed, it would be possible for the contact 13 to close due to the clearance of the first track section before the contact 11 ofthe second track section isopencd, so that the home relay 3H is momentarily energized. If the arrangement were such that the home relay 3H directly controlled the pole changer relay 31 C, as is the case in my prior application, it would have been possible for the relay 3H and 3PC to momentarily pick up and thereby cause dropping of the stick relay 3S. This would not establish a dangerous condition, because all it would do'is revent another train following the train in question, which of course would be entirel safe, but would not facilitate proper tra c movement.

Let us. now see what, transpires when the train in question moving from right to left passes entirely off of the track circuit containing track relay 2T. 'This'causes the con tact 11 of this track relay 2T to close and complete an energizing circuit for the home relay 3H. When the home relay 3H picks up the opening of its back contact 33 will open one stick circuit for the stick relay 38, but the other stick circuit thereof is still intact and therefore the stick relay 38 remains energized. The closure of the contact 15 of the home relay 3H, however, completes an energizing circuit for the thermal relay TR which may be traced as follows :be-

ginning at the terminal B+ front contact 15 of the home relay 3H, wire 40, winding of the thermal relay TR, wire 41, back contact 19 of the relay 3PC to the terminal B. With the thermal relay TR energized the leaf, or prong, 42 constructed of thermal metal, will after a time close the contacts 4243 and complete a pick up circuit for the relay 3P0, which circuit may be traced as follows :beginning at the terminal -B+, front contact 15 of relay 3H, wire 16, winding of the relay 3PC, wires 17 and 44, contacts 4243 of the thermal relay TR, to the terminal B. It may be pointed out here that the relay TR may constitute any suitable form of slow acting device and if a thermal responsive device is used, it preferably is made of two metals having different temof expansion welded toperature .co-efiicients gether.

The completion of this circuit causes the relay 3P0 to assume its energized condition, upon which the stick circuit therefore heretofore traced is completed. As soon as the pole changer relay 31 C is energized the energizing circuit for the thermal relay TR just traced, is broken at the contact 19 of the relay 3P0. It is thus noted that the relay TR may be a rather ineflicient large energ consuming device, because it is energized or a short time only. As soon as the relay 31 C assumes its energized condition, the other stick circuit for the relay 38 is broken at the contact 35, and the stick relay 3S assumes its de -ener- ,ceive energization through the contact 20 of the relay 3P0.

Let us "now assume that an engine and .tender unit is running alone, and moving from left to right between the signals 1 and 3, under which condition the relays 3H and 31 C are de-energized and in turn all the home and pole changer relays for the signals covering west bound traffic are held at danger by reason of the usual tumble down circuit, because no west bound trains should enter the single track section in-question so long as there is an east bound train moving therein. Upon the passage of the short train in question from the tracksection containing track relay 2T upon the track section containing the track relay 3T, the contact 11 will be immediately closed due to the quick picking up of the track relay 2T and possibly will be closed before the contact 13 of track relay 3T is opened, because the track relay 3T is slow to drop, its winding being shunted by the train thus causing it to act like a shorting slug, and therefore the home relay 3H is momentarily energized. In accordance with the present invention, due to the delay imposed by the thermal relay, the 'pole changer relay 3P0 cannot pick up for an, appreciable time, so that the pick up circuit,

for the stick relay 3S will not be completed even though it is closed at contact 22 of the track relay 3T, because this pick up circuit is open at the contact 24 of the relay 3P0. If, on the other hand, the home relay 3H directly controlled the ole changer relay 3P0, it might be possible or the pole changer relay 31 C to pick up and close its contact 24 in which event the stick relay 3S would have been picked up.

The picking up of the stick relay 3S b(y an east-bound train, whiclris thus avoide by my invention is objectionable, because it permits the clearing of. the next opposing signal, and under certain conditions of train movement, the necessary signaling protection for opposingtrains is not provided.

The present invention, which generally speaking resides in the provision of electroresponsive slow acting means for controlling the picking up of a stick relay, has for convenience been shown applied to a specific form of absolute-permissive-block signaling system only. This application of the invention is not to be construed as a limitationot its field of use nor of the scope of the inven tion, since it is recognized that it may be applied to any system where a stick relay is to be picked'up only in the event a certain contact has been closed for an appreciable time, or anywhere where a device is to be operated a predetermined and an appreciable period of time after a control contact therefore closes and Where the means for obtaining such delay consumesso much energy that it is expedient to employ applicants energy saving arrangement to substitute an eflicient stick relay for the ineflicient slow acting device after this slow acting device has carried out-its function of delaying such operation. In some cases it may be expedient to connect a plurality of slow-acting thermal devices, such as the device TR of Fig. 1, so as to act sequentially so as to provide a greater time interval. uch an arrangement is shown in the modification of Fig. 2. In this modification, the circuits controlling the relay 3S, are the same shown in Fig. 1 and need not be described. The pole-changer relay 3P0 is normally maintained energized by a stick circuit including its front contact 19*, wires 16, 17, and 18, and a front contact 15 of the home relay 3H the same as in Fig. 1. After the relay SPC has been de-energ'ized by opening of its stick circuit, thereby closing its back contact 19", when the home relay 3H is again energized, a circuit for the heating coil of the thermal element TR is established and may be traced from B through the back contact 19, wire 50, front contact 15 of relay 3H3 wires 51 and 52 through the heating coil to C. When the thermal device TR closes its contact 43, current is supplied to the heating coil of the thermal device TR", which in turn, after an interval of time, closes its contact 43", supplying current to the heating coil of the thermal device TR. The closing of the contact 43 of the last thermal device TR establishes a pick-up circuit for the relay 3PC, thereby energizing this relay for the same purpose, and with the resultant pperations explained in the modification of Having thus shown and described different specific embodiments of the invention, this having been done for the purpose of facilitating the description of the 'nature of the invention and the manner in which it may be applied to existing or other railway systems, it is desired to have it understood that the devices and apparatus illustrated have not been illustrated for the purpose of showing the scope of the invention nor the exact apparatus preferably employed in practicing the invention and that various changes, additions and modifications may be made to adapt the invention to the particular problems encountered in practicing the same, all without departing from the spirit and scope of the invention and the idea of means underlying the same, except as demanded by the scope of the following claims.

lVhat I claim as new is 1- 1. In combination, a relay of the stick type having a stick circuit including its own front contact closed only when it assumes its energized condition and having a pickup circuit, and a slow acting electro-responsive device having contacts closed only after said electro-responsive device has been energized for a predetermined period of time, said pickup circuit including the contacts of said electro-responsive device, and the energizing circuit of said electro-responsive device including a back contact of said stick relay.

2. In combination, a relay of the stick type having a stick circuit including its own front contact closed onlywhen it assumes its energized condition and having a pick-up circuit, and a slow acting thermal device having contacts closed only after it has been electrically energized for a predetermined period of time, said pick-up circuit including the contacts of said thermal device, and the energizing circuit of said thermal device including a back contact of 'said stick relay, and control contacts in said stick circuit for controlling said stick relay.

3; In combination, a relay of the stick type having a stick circuit including its own front contact closed only when it assumes its energizcd condition and having a pick-up circuit, and a slow acting thermal device having contacts closed only after it has been electrically energized for a predetermined period of time, said pick-up circuit including the contacts of said thermal device, and the energizing circuit of said thermal device including a back contact ofysaid stick relay,'and control contacts in both said pickup and stick circuits of said stick relay and x in the energizing circuit for said thermal p stick relay.

device for controlling energization of said 4. In a single track railway signaling. system of the absolute-permissive-block type; the combination with a signal and control apparatus therefore including a home relay, a pole changer relay, a stick relay and a thermal device; a divided block in advance of said signal containing a plurality of track sections each having a track circuit including the usual track relay; a circuit for energizing said home relay including in series the contacts of said track relays; a stick circuit for said pole changer relay including a front contact of said home relay; a pick-up circuit for said pole changer relay including a contact of said thermal device and a front contact of-said home relay inseries, a pick-up circuit for said stick relay including a front contact of said pole changer relay; and a stick circuit for said stick relay including a back contact of said home relay.

5. A single track railway signaling system of the absolute-permissive-block type; the combination with a signal and control apparatus therefore including a home relay, a pole changer relay, a directional stick relay and a slow acting relay; a divided block in advance of said signal'containing a plurality of track sections each having a track circuit including the usual track relay; a circuit for energizing said home relay including in series the contacts of said track relays; a stick circuit for said pole changer relay -in cluding a front contact of said home relay; a pick-up, circuit for said pole changer relay including a contact of said slow acting relay and a front contact of said home relay in series, a pick-up circuit for said stick relay including a front contact of said pole changer relay; and a stick circuit for said stick relay including aback contact of said home relay.

6. In a single track railway signaling system of the absolute-permisssive-block type, the combination with a directional stick relay for permitting trains to follow each other through a single track section without permitting trainsvto move toward each other, a slow dropping relay for permitting said stick relay to pick-up when there is a train moving in a certain direction .by a control point, and

supplemental means for delaying the picking-up of said slow dropping relay to prevent said directional stick relay picking up upon a momentary application of energy thereto.

7. In a single track railway signaling system of the absolute-permissive block type,

tion without permitting trains to move toward each other, a slow dropping stick relay for permitting said directional stick relay to 'pick-up when there is a train moving in a certain, direction by a control point, and electro-thermal' responsive device for closing a pick-up circuit for said slow dropping stlck relay only after an interval of time has elapsed since said electro-thermal responsive device was electrically energized.

8. In a single track railway signaling system of the absolute-permissive-block type, in combination with the usual directional stick relay provided for permitting trains to follow each other through a single track section without permitting trains to move toward each other, a slow dropping stick relay for permitting said directional stick relay to pick-up when there is a train moving in a certain direction by a control point, an electro-thermal responsive device rendered active an interval of time after being energized for closing a pick-up circuit for said slow droping stick relay and having an energized circuit including a back contact of saidslow dropping relay, and control contacts in the energizing circuits of said slow dropping relay and said electro-thernial responsive device.

9. A single track railway signaling system of the absolute-permissive-block type, the combination with the usual directional stick relay provided for permitting trains to follow each other through a single track section without permitting trains to move toward each other, a slow dropping stick relay for permitting said directional stick relay to pick-up when there is a train moving in a certain direction by a control point, an

. electro-thermal-respons1ve device for closing a pick-up circuit for said slow dro pingstic relay only after an interval 0 time has.

clasped after said electro-thermal responsive device is electrically energized, and means .for de-energizing said electro-thermal relay; a pole changer relay for controlling the signal lamps of the light signal of said system and the home relay of the next signal in the rear, means for-rendering said pole changer relay slow to dro to permit picking up of the directional stic re ay and avoiding flashing of the danger lamp of said signal lamps, and other means for delaying the picking up of said pole changer relay.

11. In a single track railway system of the absolute-permissive block light signal type;

.' pole changer relay'governed by said home relay forcontrolling the signal lampsof a particular light signal of said system and the home relay of the next signal in the rear of said light signal and having a normally opened and normally closed contact; a pickup circuit for said directional stick relay including said normally closed contact; astick circuit for said directional stick relay including said normally opened contact; and means for delaying the energization of said pole.- changer relay after de-energization thereof for a time interval following the energization of said home relay.

12. In an absolute permissive block signaling system, the combination with the usual home relay associated with an intermediate signal of a single track section of such system, a track relay for each of two successive track circuits adjacent said intermediate signal, a slow dropping relay, a slow acting thermal relay controlled by said home relay for picking up said slow dropping relay, and a directional stick relay having a pick-up circuit including a front contact of said slow-dropping relay and a stick circuit including a back contact of said slow-drop ping relay.

13. In an absolute-permissive-block signaling system, the combination with an intermediate signal, two track sections in advance of said signal each having a track relay, a home relay controlling the indications of said signal and de-energized if either of said track sections is occupled, a slow-releasing relay, a thermal relay controlled by said home relay for closing a pick-up circuit for said slow-releasing relay, a directional stick relay, a pick-up circuit for said directional stick relay including a front contact of said slow-releasing relay and a back contact of the track relay of the track section next in advance of said signal, and a stick circuit for said directional stick relay including a back contact of said home relay and a back contact of said slow-releasing relay in multiple.

14. In a signaling system of the type described, a normally inactive thermal device having normally open contacts, a slow-releasing polechanger stick relay having a pick-up circuit including said normally open contacts, an energizing circuit for said thermaldevice including a back contact of said pole-changer relay, and a directional stick relay having a pick-up circuit, including a front contact of said pole-changer relay.

15. In combination, a relay of the stick type, having a stick contact, a control relay. :1 slow acting relay closing a contact only after a predetermined time of energization thereof, an energizing circuit Ior said slow acting relay including a back contact of said stick relay and a front contact of said control relay, a pick-up circuit for said stick relay including the contact of said slow acting relay, and a stick circuit for said stick rel'ay including a front contact of said control relay and the stick contact of said stick relay, whereby the picking up of the stick relay is delayed by said predetermined period of time, said slow acting relay is (lo-energized upon energization of said stick relay and said stick relay if once picked up is held energized so long as said control relay is energized.

16. In an absolutepermissive-block signaling system, in combination with a directional stick relay having a pick-up circuit, a slowdropping relay having a front contact included in said pick-up circuit, a home relay controlling said slow-dropping relay, and other means governed by said home relay for delaying the energization of said slow-dropping relay after de-energization thereof by said home relay for a time interval following the re-energization of said home relay, whereby the closing of said front contact in the pick-up circuit for said directional stick relay, after the opening thereof, is delayed by the action of said other means.

17 In a single track railway signal system of the absolutepermissive-block light signal type; the combination with the usual home relay, track relays controlling said home relay and a directional stick relay; a slow-releasing pole changer relay for controlling the signal lamps of a particular light signal of said system and the home relay of the next signal in the rear of said light signal and having a normally open and a normally closed contact; a pick-up circuit for said directional stick relay including said normally closed contact; a stick circuit for said directional stick relay including said normally open contact; and electrically operable time-responsive means rendered effective only upon deenergization of said pole-changer relay and energization of said home relay for delaying the r-energization of said pole-changer relay for a limited interval of time.

18. In a railway signaling system, a plurality of track relays, a line relay controlled by said track relays, a repeater relay governed by said line relay, and electrically operable means for delaying the energization of said repeater relay when once de-ener'gized for a time interval following the re-energization of said line relay.

19. In a railway signaling system, aplurality of track relays, a line relay controlled by said track relays, a slow-releasing signal relay having an energizing circuit including a front contact of said line relay, a directional relay responsive to the direction of y electrically operable means for delaying the energization of said signal relay after deenergization thereof fora time interval subsequent to the re-energization of the line relay.

20. In a railway signaling system, a line relay controlled by a plurality of track circuits, a slow-releasing signal relay governed by said line relay, a color light signal, control circuits for said signal governed by said line relay and said signal relay, and electrically operable time responsive means for delaying the energization of said signal relay after de-energization thereof for a time interval subsequent to the energization of a line relay.

9.1. In a railway signaling system, a line relay governed by a plurality of track circuits, a repeater relay, a stick circuit for said repeater relay including a front contact of the line relay, and electrically operable means set into operation upon d-e-energization of the repeater relay and energization of the line relay for picking up said repeater relay after a time interval of delay.

22. In a railway signaling'systeni, a line relay, a slow-releasing repeating relay governed by said line relay, a directional relay controlled by said repeater relay, and a thermal time element device for delaying the energization of said repeater relay after each de-energization thereof for a time interval subsequent to the energization of said line relay.

23. In a railway signaling system, a line relay controlled by a plurality of track circuits, a slow-releasing repeater relay, a stick circuit for the repeater relay opened upon de-energization of the line relay. a pick-up circuit for said repeater relay. and a thermal time element device controlled by a back contact of said repeater relay and a front contact ofsaid line relay for establishing said pickup circuit after an interval of delay, and

signaling means controlled by said repeater relay.

24. In a signaling system for single track railroads, a line relay governed by a plurality of track circuits, a slow-releasing repeater relay, a stick circuit for the repeater relay opened upon de-energization of said line relay, a directional relay governed by one of said track relays and by said repeater re lay. and a thermal element controlled by a hack contact of said repeater relay and a front contact of said line relay for delaying the energizati-on of said repcaterrelay after interruption of its stick circuit for a time interval following re-energization 0f the line relay.

25. In a system of signaling for single track railroads, a line relay, a repeater relay governed by said line relay, a directional relay having a holding circuit including a. back contact of said repeater relay, and time- SEDGWICK N. WIGHT.

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