US1506630A - Highway-crossing signal for railways - Google Patents

Highway-crossing signal for railways Download PDF

Info

Publication number
US1506630A
US1506630A US549777A US54977722A US1506630A US 1506630 A US1506630 A US 1506630A US 549777 A US549777 A US 549777A US 54977722 A US54977722 A US 54977722A US 1506630 A US1506630 A US 1506630A
Authority
US
United States
Prior art keywords
signal
lever
arm
bell crank
latch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US549777A
Inventor
Carl R Graves
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US549777A priority Critical patent/US1506630A/en
Application granted granted Critical
Publication of US1506630A publication Critical patent/US1506630A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B61RAILWAYS
    • B61LGUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L29/00Safety means for rail/road crossing traffic
    • B61L29/24Means for warning road traffic that a gate is closed or closing, or that rail traffic is approaching, e.g. for visible or audible warning
    • B61L29/26Means for warning road traffic that a gate is closed or closing, or that rail traffic is approaching, e.g. for visible or audible warning mechanically operated

Description

Aug. 26 1924.
C.- R. GRAVES HIGHWAY CROSSING SIGNAL FOR RAILWAYS Filed April 5 1922 5 Sheets-Sheet 1 wue/wbo a [Lari 1%.Erszea C. R. GRAVES HIGHWAY CROSSING SIGNAL FOR RAILWAYS Aug. 26 1924,
Filed April 5, 1922 5 Sheets-Sheet 2 RAMROAD QRQSSING Aug. 26 1924.
C. R. GRAVES HIGHWAY CROSSING SIGNAL FOR RAILWAYS Filed April 5. 1922 5 Sheets-Sheet 5 Aug 2%, 1924.
C. R. GRAVES HIGHWAY CROSSING SIGNAL FOR RAILWAYS Filed April 5,
1922. 5 Sheets-Sheet 4 0 f, 7 a/aav ammo c Earl. R. Braves Aug. 26 1924.
C. R. GRAVES HIGHWAY CROSSING SIGNAL FOR RAILWAYS Filed April 5, 1922 5 Sheets-Sheet 5 Patented Aug 26, 1924.
U ET i) S T at. T E S CARL. n. snavns, or CLARION, IOWA.
HIG'EWAY-GROSSING SIGNAL FOR RAILWA'YS.
Application filed April 5,
1 '0 (ZZZ whom it may concern:
Be it known that l, CARL B. Gnams, a citizen of the United States, residing at Clarion, in the county of lVright and State of Iowa, have invented certain new and useful Improvements in Highway-Crossing Signals for Railways, of which the following is a specification, reference being had to the accompanying drawings.
This invention relates to crossing signals on railroads, and particularly to crossing signals of that character wherein the approach of train toward the crossing sets the signal to a danger or stop position and the. passage of the train past the crossing restores the signal to its normal or go position.
The general object of the invention is to provide a signal of this character particularly adapted to be used on railroads for preventing accidents happening at crossing includes a semaphore, a dangei cl a lamp, and a shield at and movable with the seinaoho when the semaphore is in its 'on, is disposed in front 3 and which, when the semaphore is i aoscd in its danger position, is disposed in iLont of the clear lan'ip, the lamps being kept burning at all times so that on foggy day and under like circumstances the danger s nal or the clear signal will be plainly visible, these lamp signals, of course, being p 'icularly n cessary at night.
A further object this charact its clear posi i position by a saring, a i releasing, or as it may be ned, signal setting means disposed on each. side of the. crossing and suitable d? tance therefrom, which will be actuated by a movement of a train in one or the other d e ion toward the crossing and which will tiicieby release the latch and permit the signal '0 be shifted to its danger position, to povide a signal restoring means disposer 11 each side of the crossing which, after a train has passed, will act to restore the signal to its normal position.
A still further object in this connection is to provide for the setting and restoring of a signal of b a latch in its uanger ov de the latch 1922. Serial No. 549,777.
the signal if a train moves onto a siding or moves off the siding.
Another object has to do with the details of construction of the setting and restoring means so that the movement of the train in one direction over a setting means, for instance, will actuate this setting means but will not actuate the signal mechanism, while the movement of the train in the opposite direction will not only actuate the setting means but will actuate the signal itself, the same construction being applicable to the restoring means.
Other objects have to do with the details of construction and arrangement of parts as will appear more fully hereinafter.
My invention is illustrated in the accompanying drawings, wherein Figure 1 is a plan view of a railway track and siding and a highway crossing, the signal mechanism being shown diagrammatically;
Figure 2 is a side elevation of the upper portion of the railway signal itself;
Figure 3 is an end elevation of the upper portion of the signal post and the lamp housing;
Figure 4: is a vertical sectional view through the lamp housing;
Figure 5 is a fragmentary top plan view showing the semaphore actuating means and releasing means and the mechanism for restoring the signal;
Figure 6 is a fragmentary top plan view showing the device for restoring the signal as disposed in conjunction with the main track and the side track;
Figure 7 is a side elevation showing one of the restoring members 68 and connected parts;
Figure 8 is a section on the line 8 8 of Figure 7;
Figure 9 is a section on the line 9-9 of Figure 7 Figure 10 is a side elevation of the lower portion of the semaphore post and the signal setting mechanism;
Figure 11 is a side elevation of the lower portion of the signal post and the restoring mechanism Figure 12 is an end elevation of the construction shown in Figure 6, the rails being in section;
Figure 13 is a top plan view of a rail, the signal setting members and allied parts;
Figure 1d is a like view to Figure 13, but showing the other semaphore setting mecha nism;
Figure 15 is a fragmentary side elevation of the construction shown in Figure 14:;
Figure 16 is a section on the line 1616 of Figure 15;
Figure 17 is a section on the line 1717 of Figure 15;
Figure 18 is a section on the line 1818 of Figure 15.
Referring to these figures, A designates the main track having the rails a, while B designates a siding which is connectible with the main track by the switch rails 6, these switch rails being shiftable by means of the usual switch stand C. The highway crossing is designated generally D and the crossing signal is designated generally E, this crossing signal being disposed adjacent the highway crossing so as to be obvious to traffic.
The crossing signal E is illustrated more particularly in Figures 2 to 41-. It comprises the post 10 carrying at its upper end the pivoted semaphore arm 11 which is constructed after the manner of the usual semaphore arm, this semaphore arm being pivoted between the post and the bracket 12 by means of a bolt 13. Also mounted upon this bolt 13 is an angular lever 14.- carrying at its upper end a screen or shield 15 and having its arm 16 operatively connected to the semaphore arm 11 so that the lever 14 and the semaphore arm move together. Disposed upon the top of the post is the lamp casing 17 having two glazed openings, one of. these openings being glazed with red glass 18 and the other opening being glazed with green glass 19. While I have referred to green and red glass, I wish it understood these are only preferable colors. White glass might be substituted for the green, but red glass is almost imperative forthe reason that red is almost always used as a danger signal. This lamp casing has the usual ventilator 20 at its top and a door 21 at one end and disposed within the lamp casing is the lamp 22 having two burners, one in line with the green glass and one in line with the red glass. The detailed construction of the lamp forms no part of my invention, nordoes the particular mounting for the semaphore arm and for the shield 15. The rear end of the semaphore arm is circular in form, as at 23, and this circular end has two latching recesses 24 and 25 extending tangentially to a circle concentric to the axis of movement 13.
Mounted in a guide frame 26 is the shank 27 of a latch 28, this latch being rounded at its upper end, this rod 27 having a shoulder 29. This rod 27 passes through apertures in the outwardly projecting ends of the frame 26, and disposed within this frame 26 is a coiled compression spring 30 which bears at one end against the frame and at the other end against the shoulder 29 so that this latch rod is urged upward by the spring 30. The lower end of the shank of the latch 27 is pivotally connected to a connecting rod per and lower supporting brackets 3d and 35. The rod has a shoulder 36 and a relatively long compression spring 37 is disposed between the bracket 35 and this shoulder 36 and urges the rod 33 upward. The lower end of the rod is pivotally connected to a connecting rod 38 which extends down to the lower end of the post and is there connected to the operating mechanism, as will now be described.
The lower end of the connecting rod 38 is connected to the rear end of a lever or arm 39 which is pivoted on a horizontally disposed pivot pin 4:0 mounted in supports 41. pins or lugs 42. Also pivoted upon this pivot pin 10 is a bell crank lever 43 and a bell crank lever 44, the rearwardly extending horizontal arms of the bell crank levers 4:3 and 44 having notches in their under edge faces which engage over the laterally projecting lugs d2. Springs 45 are connected to the downwardly projecting arms of the bell crank levers 13 and 4%, these springs being in turn connected to adjusting bolts 46 passing through brackets 47 attached to the base 48 of the signal. By this means these springs 15 may be tensioned to any suitable degree. V
The downwardly extending ends of the arms of the bell crank levers 13 and 1 1 are pivotally connected to a pair of horizontally disposed rods 49 and 50 which extend to hell crank levers 51 pivoted upon the base, these bell crank levers being set reversely to each other. The outer ends of the bell crank levers are pivoted to connecting rods 52 extending in opposite directions, each of these connecting rods being sectional in form and provided with a turn buckle 53. The outer end of one of the connecting rods 52 is pivoted to a lever 54, and the outer end of the other connecting rod 52 is pivoted to a three-armed lever 55 (see Fig. 6). The lever 54 is connected by a link 56 to a rod 57 which passes through the outwardly pro- This arm 39 has laterally'projecting jecting ends 58 of a frame or guide 59 which isbolted to one of the rails A. This rod 57 is provided with a shoulder 60 and with a shoulder 61. This shoulder 61 is recessed upon opposite faces. Sliding on this rod 57 is a sliding plate 62, and disposed between this sliding plate 62 and the shoulder 60 is a coiled compression spring 63. Engaged with the sliding plate 62 are two longitudinally extending rods 64 which operate through the recesses in the shoulder 61 and which are connected by a yoke 65 at one end, which yoke'has a medially disposed lug pivotally connected to connecting rods 66. These connecting rods are deflected so that the ends of the connecting rods remote from the yoke or cross head 65 are disposed closely adjacent the rail 0. and are engaged by a bolt 67, which in turn is connected to the lower end of a wheel operated trip or lever 68 which is pivoted by a bolt 69 to the rail. The upper end of this lever is formed with two angular faces, one of the faces 70 being relatively short and the other 71 relatively long, (see Fig. 7).
This trip or lever 68 is a restoring lever, in that it restores the signal after it has been set to its danger position to a safety or clear position. The lever 55 (Fig. 6) is connected by a like link 56 to a rod 57 moving through the ends 58 of a frame 59 and is in all respects constructed the same as the members just heretofore described and is connected by the connecting rod or rods 66 to a second restoring lever 68. I have so far described two restoring levers and I will distinguish one from the other by the exponents a and b, but it will be understood that both of the restoring levers are alike but that they are set reversely to each other. In other words, the long faces 71 of the restoring levers 68 and 68 confront each other, while the short faces face away from each other. There is a third restoring lever connected with the side track F and this restoring lever I designate 68. This restoring lever 68 is connected to the third arm 72 of the lever 55 by means of a transversely extending connecting rod 73 and bell crank lever 7% which is connected to a link 56, in turn connected to the restoring lever 68 by the parts 57, 58, 60, 61, etc., as heretofore described.
The connecting rod 31 at its lower end is operatively connected to an arm 75 which is smaller than but analogous to the arm 39 and which is pivoted on a transverse pivot pin 76 mounted in a stand 77. Also pivoted upon the pivot pin 76 are the two bell crank levers 7 9 and 80, the forwardly extending arms of which are notched to engage over the pins 78. The downwardly extending arms of the bell crank levers 79 and 80 are connected to coiled contractile springs 81, in turn connected to tensioning bolts 82 passdepending upon'the direction in which the ing'through a' bracket-8311sdescribed'iforithe arms 43 and44. 'Thedownwardlyextending arms of the bell crank levers 799.1}(180 are connected to connectin rods-84 and 85, which in turn are connected to-reversely disposed bell crank levers86 adjacent thettrack. Theconnections between *these bell crank levers and the setting or releasing' track levers are alike and, therefore, the description applicable to one is'applicable to the other. Each bell crank lever 86 is ,pivoted to a longitudinally extendingconnecting rod 87 which extends beneath the corresponding frame 59 and extends up or down *the tra'c'k, as the case maybe, for-anydesireddistance from the crossing,-the connectingrod87'having a downwardly deflected--section '87 in its length for this purpose. This connecting rod '87 also has a turn buckle 88 in its length. At asuitable distance from the crossing the connecting rod .87 is pivoted to v a longitudinally movable rod 89 which passes through the outwardly projecting lugs "of a guide frame 90. The rod 89 has at one end the shoulder 91 and atthe opposite end-a s'houlder 92, this last named shoulder be'ing recessed upon its upper and lower faces.
Disposed forward ofthe forward lug-of frame is a yoke or cross head 9-3 having two rearwardly extending rods "94 which pass through the perforations in the frame lug and pass on each side through the recessed portions of 'the shou'lderL92and-engage with a slide plate '95. A-coiled'compression'spring 96 bears at oneend against 5 the shoulder 91 and at'the other end against this slide plate .95. The yoke 93 is operatively connected to connecting 'rodsi96, which in turn are connected to the lower end of a trip lever 97 which is pivoted to the rail by a pivot bolt 98. The upper end-of this trip lever-97 is angular to'provide-a -relatively long outer face 99 and a relatively short innerface 100.
Both the trip levers 97 and 97" are of the same character but in the case of the All the trip levers 68 68 97 and "97 extend slightly'above the rail a so that the wheel of a car will ride against the inclined faces 99 or 1.00'or 70 and '71and oscillate the trip lever in-one direction or the other,
car is running.
Assuming that the semaphore i-sset in its safety position, that is with the semaphore extending downward and the shield 15 over the lamp 18, then upon the approachof -a I? exerted upon the connecting rods 96. This will exert strain upon the slide rods 94 and upon the slide plate 95 which, abutting against the shoulder 92, will cause the rod 89 to be drawn longitudinally which, through the connecting rod 87, the bell crank 86, and the rod 84, will act upon the bell crank lever 79, drawing down on the rearwardly projecting arm of this bell crank lever and, therefore, drawing down upon the arm 75. This will pull downward upon the latch rod 81 and the latch 27, releasing the latch from engagement with the keeper notch 25. The spring 37 will then, act to shift the semaphore upward to the position shown in Figure 2 and the latch will engage in notch 24. The wheel will move onward and as soon as it has moved onward the lever 97 will move back to its neutral position by reason of the tension springs 81 without, of course, affecting the arm which is held in its raisedposition by reason of the bolt 27 having been pushed upward by the spring 30. \Vhen the forward wheels of the locomotive strike the lever 68", they will shift this lever in a counter-clockwise direction, which will shift the connecting rod (36 rearward or toward the right in Figure 1, but this will merely act to compress the spring 63 thereof without affecting in any way the signal or the latch. After the train has passed the crossing it will strike the lever 68 and shift this lever in a counter-clockwise direction or toward the left in Figure7, and this will draw upon the connecting rods 66 and exert draft upon the rod 57, the link 56,
shift the lever 54 in a direction to exert draft upon the rod 52, and this through the bell crank 51 exerts a pull upon the rod 49 and through the bell crank lever 43 exerts a downward pull upon the connecting rods 38 and 32 to'draw down the semaphore.
The upper end of the 1atch27 'is rounded or beveled, as seen in Figure 2, so that as the semaphore moves downward it crowds or wedges'downward on the latch 27 and against the action of the spring 30, and. the latch remains in its depressed position until the semaphore has been fully pulled downward to its safety position and notch 25 is above the latch, whereupon the latch again springs out to lock the semaphore in its fully lowered position with the-spring 37 compressed. A train coming from the west or from the left hand side of Figure '1 .will operate the lever 97 in the same manner as the lever 97 is operated which, by the means heretofore described, will act to release the latch and again permit the semaphore to take its stop or danger position. This train will pass over the restoring lever 68 without affecting the mechanism for the reasons heretofore stated, but when it reaches the restoring lever 68 it will shift the semaphore will be shifted to its danger position, but when the train has reached the restoring lever 68 it will actuate this restoring lever which, through the medium of the bell crank 74 and the rod 7 3, will shift the semaphore to its safety position.
It will be seen that the operation of either one of the'setting levers 97 or 97 while it will act upon the semaphore, will not affect the other setting lever, and that the operation of either one of the restoring levers 68 68 or 68 will not affect the operation of any of the other restoring levers. It will be understood that the longitudinally extending connecting rods, such as the rods 57, 87, 52, 49, 85, etc, and like rods will be supported upon roller supports, as the operating rods of switches and semaphores'are supported today in railroad practice. I have not illustrated these supporting rods, as they are well known and are obvious. The rods 84, 85, 50, 49, the levers 51 and 86, and the levers 43, 4 4, 39, 75, 79 and 80 will be preferably housed or protected from the weather and from any intermeddling.
It will be seen that with this construction an approaching train automatically sets the crossing signal to danger but when the train has passed the crossing it automatically resets it to a safety position, and that by the mechanism described a signal may be provided for a single track which will set the signal to danger upon the approach of a train in either direction upon this single track, and reset to a safety position upon the recession of the train in either direction on a single track, and that also this construction provides for the setting of the signal to danger before the entrance of a train onto a siding which crosses the highway and for the setting of the signal to a safety position when the train is stationary on the siding and has passed the highway.
While I have illustrated certain details of construction and arrangement of parts, it
will be understood that I do not wish to other and associated with the firstnamed arm, the-movement of either of the second named arms in one direction acting to shift the first named arm in a direction to affect the signal but not affecting the other of the second named arms, and separate train actuated means operatively connected to the second named arms.
2. In a signal, a shiftable signal member, means urging the signal member in one direction, a latch for holding the signal member against said urging means, actuating'means for the'latch including a pivoted arm operatively connected to the latch and movable in one direction to retract the latch, a pair of pivoted arms independent of each other and associated with the first named arm, the movement of either of the second named arms in one direction acting to shift the first named arm but not af-- fecting the other of the second named arms, and separate train actuated means connected to the second named arms for shifting them to thereby release said latch and permit the signal to shift under the act on of said urging means, means for returnlng the signal to its initial position including a pivoted arm, operatively connected to the signal, a pair of arms independent of each other and associated with the main signal actuating arm, the movement of eithenof said second named arms in one direction acting to shift the main arm but not affecting the other of the second named arms associated therewith, and separate train actuated means connected to the pair of arms associated with said main arm.
3. In a signal, a shiftable signal member and actuating means therefor including a pivoted arm having studs projecting laterally thereto in opposite ClIIGCtlODS, a pair of pivoted bell crank levers mounted on each side of the arm and having arms extending approximately parallel to the first named arm and resting upon said studs means resisting movement of each bell crank lever in a direction to depress the first named arm, separate train actuated devices, and operative connections between the train actuated devices and the depend ing arms of said bell crank levers.
4. A railway crossing signal including a signalling member mounted for movement toward or from a danger position and resiliently urged to its danger position, a latch holding the signalling member in a safety position against the action of said urging means, train operated, oscillatable members on both sides of the railway signal and remote therefrom, a pivoted arm operatively connected to the latch, a pair of hell crank levers on each side of the pivoted arm, the arm having transversely extending lugs over which the bell crank lever is engaged and upon which they rest, operative connections between said arm and the latch, operative connections between? said bell crank levers and said train operated members permitting a movement of said member in a direction toward the crossing to operate said bell crank levers and a movement of the member in. a direction away from the railway crossing'to'beinetfective to operate the bell crank levers and the latch, oscillatable train operated members disposed on both sides of the crossing and adjacent thereto, a pivotally mounted arm operatively connected to the crossing to shift it, a pair of bellcrank' levers associated with the arm, the arm having'laterally projecting lugs disposed over the bell: crank levers and resting thereon,
and operative connections between said bell crank levers. and. the second named track members whereby to cause the oscillation of said bell crank levers upon the engagement of a train with either of said members.
5. A railway crossing signal including a signalling member mounted for movement toward or from a danger position and resiliently urged to its danger position, a latch holding the signalling member in a safety position against the action of said urging means, train operated, oscillatable members on both sides of the railway signal and remote therefrom, a pivoted arm operatively connected to the latch, a pair of hell crank levers on each side of the pivoted arm, the arm having transversely extending lugs over which the bell crank lever is engaged and upon which they rest, operative connections between said arm and the latch, operative connections between said bell crank levers and said train operated members permitting a movement of said member in a direction toward the crossing to operate said bell crank levers and a movement of the member in a direction away from the railway crossing to be inefiective to operate the bell crank levers and the latch, oscillatable train operated members disposed on both sides of the crossing and adjacent thereto, a pivotally mounted arm operatively connected to the signal to shift it, a pair of bell crank levers associated with the arm, the arm having laterally projecting lugs disposed over the bell crank levers and resting thereon, operative connections between said bell crank levers and the second named track members whereby to cause the oscillation of said bell crank levers upon the engagement of a train with either of said members, each of the connections between a bell crank and the corresponding train operated member including a connecting rod and having spaced shoulders, a yoke having sliding engagement on the rod between the shoulders, and a spring urging the yoke against one of said shoulders, the yoke being operatively connected to the corresponding oscillatable member.
6. The combination with a stretch of track and a siding, of a crossing signal mounted adjacent'the track and the siding and including a shiftable signalling member urged to a danger position and a latch holding the signalling member in a safety position against the action of said urging means, osci latably mounted, wheel operated, signal actuating levers mounted upon the rails of the track remote from the crossing signal, each being'operatively connected to the latch to cause the retraction of the latch upon the actuation of the corresponding member and each being independently operable of the other, a retraction of the latch permitting the signalling member to move to a danger indicating position, a pair of oscillatably mounted, signal restoring levers mounted against the action of said urging means,
each restoring lever actuating the signal independently of the other restoring lever and each restoring lever being only operable by a train receding from the signal, a restoring lever pivoted upon one of the rails of the side track, and operative connections between the last named restoring lever and the signal whereby to cause a retraction of the signal to its safety position upon the departure of a train from the side track.
In testimony whereof I hereunto afliX my signature.
CARL R. GRAVES.
US549777A 1922-04-05 1922-04-05 Highway-crossing signal for railways Expired - Lifetime US1506630A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US549777A US1506630A (en) 1922-04-05 1922-04-05 Highway-crossing signal for railways

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US549777A US1506630A (en) 1922-04-05 1922-04-05 Highway-crossing signal for railways

Publications (1)

Publication Number Publication Date
US1506630A true US1506630A (en) 1924-08-26

Family

ID=24194347

Family Applications (1)

Application Number Title Priority Date Filing Date
US549777A Expired - Lifetime US1506630A (en) 1922-04-05 1922-04-05 Highway-crossing signal for railways

Country Status (1)

Country Link
US (1) US1506630A (en)

Similar Documents

Publication Publication Date Title
US1506630A (en) Highway-crossing signal for railways
US1555386A (en) Grade-crossing safety apparatus
US1577173A (en) Automatic vehicle stop for railroad crossings
US788572A (en) Automatic railway-switch.
US2744703A (en) Train actuated railroad switch
US1487358A (en) Train-actuated signal for road and street crossings
US1568628A (en) Signal
US1374828A (en) Railroad-crossing gate
US1589282A (en) Street-railway switch
US2027702A (en) Lock for railway spring switches
US2238995A (en) Track switch
US481884A (en) young-
US452285A (en) Automatic railroad-signal
US818865A (en) Railway-switch.
US1550159A (en) Actuating device for railway-crossing signals
US633892A (en) Railway-signal.
US1719697A (en) Signal
US995950A (en) Safety railway-switch.
US762457A (en) Automatic railway-gate.
US874622A (en) Pneumatic signal for railway-crossings.
US950254A (en) Automatic railway-switch.
US1305930A (en) Dangeb-signal
US765487A (en) Railway apparatus.
US1332710A (en) Railroad-gate
US926022A (en) Electric block railway-signal.