US2547664A - Railway signal lighting control apparatus - Google Patents

Description

April 3, 1951 I i o. w. ROST I 2,547,664 RAILWAY SIGNAL LIGHTING CONTROL APPARATUS Filed March 2, 1949 I 2 Sheets-Sheet 2.

INVENTOR. Otto "(120st HIS A T TORNZ' Y Patented Apr. 3, 1951 UNITED STTS TENT OFFKCZE RAILWAY SHGNAL LIGHTING CONTROL APPARATUS Application March 2, 1949, Serial No. 79,167

My invention relates to railway signal lighting control apparatus, and particularly to apparatus governs trafiicmovements in the same direction as the given signal, as shown, for example, Letters Patent of the United States No. 1,7905%, granted January 27, 1931, to Lester E. Spray for Railway Signaling Systems.

In some instances, however, the circuit for energizing a control relay orwinding for the next signal in the rear, which governs traffic movements in the same direcion as the given signal, may not be suitable for controlling an approach lighting relay for the given signal. In such instances, in order to save the material and labor necessary to provide a separate control circuit for the approach lighting relay for the given sig nal, it may be possible to control the approach lighting relay for the given Signal overa control circuit for the next opposing signal in advance of the given signal.

One feature of my invention is the provision of an arrangement, embodying manuall controllable means, for at times controlling a lighting control relay for a given signal in series with a conLrol element such, for example, as a relay or other winding for the next opposing signal in ad- Vance, and for at other times controlling the same lighlng control rela by'only that portion of the control circuit for the next opposing signal in advance which is controlled. by traffic condi= tions in'the rear of the given signal. It follows that the lighting control relay, in apparatus embodying my invention, at times serves to effect the lighting of a given signal when the control circuit for the next opposing signal is deenergizeo. although it is manually controlled to be ener gized, and that the lighting control relay serves at other times as only an approach lighting relay.

With apparatus embodying my invention, one advantage is that, when a train is moving in the direction in which a given signal governs traffic movements, the lamp of the given signal is extinguished as'soon as the train has completely passed the signal and has theretofore left the approach tract: section in the rear of the given signal. Needless lighting of the given signal after a train haspassed the given signal, moving in the direction in which the given signal governs traffic movements, is thereby prevented.

Glaims. (Cl. flail-46) Another advantage, in apparatus embodying m invention, is that the lighting of a given signal mayshow that a train is approaching the given signal in either direction.

I shall describe two forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1a and 11), when placed end to end, with Fig. 1c at the left, constitute a diagrammatic view showing one form of apparatus embodying my invention, in which a two-winding lighting control relay for a given signal is arranged so that at times only one of is windings is energized in series with control means for the next opposing signal in advance, and at other times both windings of the lighting control relay are energized by only a portion of the control circuit for the next opposing signal in advance; and Fig. 2 is a diagrammatic view showing a modified form of the apparatus of Figs. 1c and 1b in which a one-winding lighting control relay for the given signal is arranged v So that at times it is energized in series with control means for the next opposing signal in ad- Vance, and at other times it is energized, in series with a resistor, by only a portion of the control circuit for the next opposing signal in advance. Similar reference characters refer to similar parts in each of the views.

Referring first to Figs. la and 1b, a stretch of railway track is shown divided by insulated joints 5 into track sections 31, ART, IT, and .ZLAI, over which trafiic movements may be made in both directions. In order to simplify the drawings, the stretch of track, although comprising two parallel series of track rails, is represented by a single line- Section HT is connected with an auxiliary track by a track switch I, and section 3T is connected with an auxiliary track by a track switch 3.

Each of the track sections is provided with a track circuit including a suitable source of current such, for example, as a battery (5 connected across the rm'ls adjacent one end of the section, and a track relay, designated by the reference character R with a distinguishing prefix which is the same as the reference character for the associated tract: section, connected across the rails adjacent the opposite end of the section.

Signals, designated by the reference characters 2R and ift, govern trafiic movemenls toward the right, as shown in the drawings, which I shall assume is the eastbound direction. Signals 2L and AL govern traffic movements in the opposite or" westbound direction. The signals may be of any suitable design such, for example, as the wellknown semaphore or the searchlight type. Each of the signals may be provided with lighting means such, for example, as lamp lLE shown for a given signal 4L.

Each of the signals is controlled by a polarized home control relay, designated by the reference character HSR with a prefix which is the same as the reference character for the associated signal. Signal 2L, for example, is controlled by relay ZLHSR, and signal 2R is controlled by relay ZRHSR. Relays 2LI-ISR and ZRHSR are shown controlled b a manually operable signal lever 2V which has a normal position n, a reverse position f to the left, and a reverse position r to the right, as shown in the drawings. Relays ZLHSR and ZRHSR are shown controlled by lever 2V through direct wires, but may be of a polar stick type controlled from a remote point through any suitable medium such, for example, as the time code apparatus shown and described in Letters Patent of the United States No. 2,273,383, granted February 17, 1942, to Clarence S. Snavely and Alfred B. Miller, for Remote Control Systems. Signals 3L and 4R are controlled by relays SLHSR and GRHSR, respectively, which are controlled by a lever 6V similarly to the manner in which relays 2LHSR and ZRHSR are controlled by lever 2V.

Each of the signals is operated, by a circuit controlled by a reverse contact or" the associated home control relay, for displaying a proceed indication. The reverse contact of each home control rela is normally open, and becomes closed when the associated signal lever is moved to a corresponding reverse control position f or 7". Contact 23 of relay ZLHSR, for example, becomes closed when lever 2V is moved to the f position, and contact 8 of relay ZRHSR becomes closed when lever 2V is moved to the r position. Each of the signals is therefore normally conditioned to display the stop indication.

Stop indication repeater relays, designated by the reference characters ZLRPR and 4LRPR, are controlled in conjunction with signals 2L and 4L, respectively. Each of these relays is energized by a circuit including a contact 9 of the associated signal which is closed when and only when the associated signal is displaying a stop indication.

A proceed indication repeater relay ERGPR is controlled in conjunction with signal 2R, and is energized through a contact 33 of signal 2R which is closed when and only when signal 2R is displaying 2. proceed indication.

Approach locking stick relays, designated by the reference characters. ZLSR and 4LSR are as:- sociated with signals 2L and 4L, respectively. Time element devices, designated by the reference characters ZLTE and 4LTE, which may be of the thermal type, are associated with relays ZLSR and ALSR, respectively.

Signal 4R, which is the next opposing signal in advance of the given signal 4L, is provided with a control element or winding which is shown as a polarized signal control relay iI-IDR. This relay is controlled by a reverse polar contact of the home control relay 4RHSR, by track relays lTR, STR, and ARTR, by approach looking relays 2LSR. and ALSR, and by pole-changing contacts of relay ZRGPR. Relays ZLSR, iTR, and iRTR are responsive to traffic conditions on the stretch of track in the rear of the given signal 4L, and relays 4LSR and 3TB. are responsive to traffic conditions on. the stretch of track between signals 4L and 4R.

A contact 29, which is operated in conjunction with switch 3, is also included in the circuit for relay 4HDR. This contact is closed when switch 3 is in the normal position, as shown, and becomes opened when switch 3 is moved to its re verse position.

Lamp GLE of signal 4L is controlled by a lighting control relay designated by the reference character 4LER. This relay is controlled, either by a reverse polar contact of relay lRHSR in series with relay 4HDR, or by a normal polar contact of relay 4RHSR and by a portion only of the control circuit for relay 4HDR controlled by traffic conditions in the rear of signal 4L.

In the modified form of apparatus shown in Fig. 2, the lighting control relay iLER, has only one control winding instead of two windings as shown in Fig. 1a. The winding of relay iLER, in the form of apparatus shown in Fig. 2, is controlled in series with relay 4I-IDR through a reverse contact of relay dRHSR, and is connected vby a normal contact of relay dRHSR through a resistor 15 with a portion only of the control circuit for relay 4HDR. which is controlled by traffic conditions in the rear of signal 4L.

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

As shown in the drawings, all parts of the apparatus are in the normal condition, that is, all track sections are unoccupied, and therefore track relays 3TB, 4RTR, II'R, and 2LATR, are energized; each of the switches l and 3 is in the normal position for a train movement along the stretch of main track; each of the levers 2V and 4V is in its normal or 11. position, and therefore the lower winding, as shown in the drawings, of each of the relays ZLHSR, ZRHSR, LHSR, and RHSR is energized; each of the signals 2L, 2R, 4L, and 4R is displayin the stop indication; each of the relays ZLRPR, 4LRPR, ZLSR, and 4LSR is energized; both windings of relay 4LER, as shown in Fig. 1a, are energized, and the one winding of relay iLER shown in Fig. 2 is energized; and relays 2RGPR and lHDR, and time element devices ZLTE and QLTE are deenergized.

As shown in Figs. 1a and 1b, the lower winding of each of the relays ZLHSR, ZRHSR, i-LHSR, and lRHSR is controlled by a circuit which includes a normal contact of the associated control lever closed in the normal position. The lower winding of relay iLHSR, for example, is controlled by a circuit which includes contact 1 of lever 4V closed in the n position. The lower winding of relay GRHSR is similarly controlled by a circuit which includes contact 8 of lever 4V closed in the n position.

Relay 4LRPR is energized by a circuit passing from terminal B of a suitable source of current, through contact 9 of signal 4L, and the winding of relay 4LRPR to terminal N of the same source of current. Relay ZLRPR is energized by a similar circuit.

Both a pickup and a stick circuit are closed for energizing relay 4LSR. The pickup circuit for this relay passes from terminal B, through contact ID of relay 4LHSR, contact H of relay 4LRPR, contact I2 of relay 4RTR, and the winding of relay ALSR to terminal N. The stick circuit for relay 4LSR is the same as the pickup circuit just traced except that it includes the front point of contact l3 of relay #lLSR, instead of contact 12 of relay iRTR. Relay ZLSR is also energized'by pickup and stick circuits which are similar to the pickup and stick circuits just traced for relay 4LSR.

Relay tLER, as shown in Figs. la and lb, is energized bya circuit which includes a portion only of the control circuit for relay 4HDR, which is controlled by trafiic conditions in the rear of signal 4L. This circuit passes from terminal B, through contact id or relay ZLSR, contact I5 of relay i'IR, back point of contact 16 or relay ZRGPR, conductor 35, the lower winding ii of relay fiLEE, contact 18 oi relay (iRHSl-c closed in the normal or left-hand position, upper winding iii of relay iLER, contact 20 of relay :iR'IR, and the back point of contact 2! of relay ZRGPR to terminal N. The circuit for relay QLER, in the form of apparatus shown in Fig. 2, is the same as the circuit just traced except that it includes the winding of relay ALER instead of the upper winding IE only of relay iLER shown in Fig. la, and includes a resistor if instead of the lower winding [7 of relay QLER shown in Fig. 1a. I shall assume that, with apparatus arranged as shown in the drawings, a westbound train enters section ELAT, deenergizing relay ELATR. Contact 52 of relay ZLATR then opens the pickup circuit described for relay ZLSR which, however, remains energized by its stick circuit previously described. i

I shall assume further that the dispatcher or leverman moves lever &v to the I position for clearing signal 2L. The upper winding of relay ZLHSR will therefore be energized by a circuit controlled by contact i of lever 2V closed in the position. Contact to of relay ELI-15R will therefore open the pickup and stick circuits fo relay ZLSR, causing relay ZLSR to become deenergized.

Contact US of relay ELSR will therefore open the circuit previously traced fo relay ALER, causing relay iLER to become deenergized. With relay 4LER deenergized, lamp LE of signal 4L will be lighted by a circuit passing from terminal BX of a suitable source of lighting current, through contact 22 of relay ILER, and lamp lLE to terminal NX- of the same source of lighting current.

With the upper winding of relay 2 li'SR energized, contact 23 of this relay will become closed, and therefore signal 2L will be operated to its proceed position by a circuit passing from terminal B, through contact 23 of relay ZLHSR, and the mechanism of signal 2L to terminal N. The arm of signal 2L, upon being moved away from its stop position, opens its contact 9, thereby deenergizing relay QLRPR which opens its contact H in the pickup and stick circuits previously described for relay ZLSR. which are,

already open at contact In of relay lower winding of relay ELI-ISR to again become energized because contact"! of lever 2V is again closed in its n position. Contact 23 of relay ZLHSR will therefore now again be opened and contact it will now again be closed. Wi h contact 23 of relay ZLHSR opened, the operating circuit for signal 2L will be opened, and therefore the arm of signal 2L will return to the stop position.

6 at contact l2 of relay ZLATR, and therefore a circuit will be completed for energizing the time element device ZLTE. This circuit passes from terminal B, through contact ll] of relay 2LHSR,

,,contact l i of relay QLRPR, back point. of contact 53 of relay ELSE, and time element device 2LTE to terminal N. Upon the lapse of a measured period of time, time element device .lL'IE will close its contact 24, thereby completing a second pickup circuit for relay 2LSR, which is the same as the pickup circuit previously described, except that it includes contact 24 of time element device ELTE instead of contact i2 of relay ZLATR.

WFv'ith relay 2LSR again energized, relay 4LER will again be energized by the circuit previously traced. The circuit for lampv 4LE will therefore be opened at contact 22 of relay dLER, causing lamp 4LE to be extinguished.

If, however, instead of stopping the train at signal 2L, the leverman permits it to proceed, then when the train enters section I T, rela iTR will become deenergized. Relay iTR, upon becoming deenergized, opens its contact 15 in the circuit previously traced for relay iLER. If the leverman then returns lever 2V to its 11. position, signal 2L will again be returned to its stop position, as previously described, and therefore relay ZLRPR will again be energized. With relay ITR deenergized, a third pickup circuit will now be closed for relay ELSE which is the same as the first pickup circuit described for this relay except that it includes contact 25 of relay ITR instead of contact E2 of relay ZLATR.

With relay ZLSR energized, its contact I4 in the circuit for relay lLER will now be closed, but with contact 15 of relay iTR in this circuit now open, relay @LER will remain deenergized. When the train enters section iRT, relay dRTR will become deenergized, and therefore its contact 28 will open the circuit for relay iLER at still another point.

When the leverman clears signal 4L by moving lever 6V to its f position, relay QLSR will become deenergized similarly to the manner in which relay ELSR becomes deenergizerl when the lever man clears signal 2L, as previously described. Contact 2? of relay iLSR will therefore now be opened, but this will not affect relay lLER because contact lfi of relay QRHSR. is now closed in the normal position. Similarly, when the train enter section 3T, deenergizing relay BTR and contact 23 of relay 3TB then opens, rela tLER will not be affected, because contact is of relay :lRHSR is closed in the normal position.

When the train leaves section GRT, permitting relay tRTR to again become energized, the circuit previously traced for relay lLER will again be closed, and therefore relay lLER will be energized and extinguish lamp ALE for signal lL.

I shall now assume that, after the westbound train has passed over the stretch of main track shown in the drawings, and all parts of the apparatus are again in the normal condition, the leverman moves lever 4V to its 1' position to clear signal'iR for an eastbound train. If, however, for any reason, relay QLSB should be deenergized at this time, relay GHDR will not become energized, because contact 2'! of relay QLSR would be open, and relay ALER will become deenergized because contact I 8 of relay lRHSR. is now in the reverse position and therefore the circuit previously traced for relay QLER is open.

If, however, relay 'tLSR is energized, and if relay 3TB is energized, then the closing of contact l8 of relay lRI-ISR in its reverse position will complete a circuit for energizing relay lLER in series with relay lHDR, this circuit passing from terminal B, through contact I4 of relay ZLSR, contact I5 of relay iTR, back point of contact it of relay 2RGPR, conductor 34, winding of relay lHDR, contact 26 of relay GLHSR, contact 21 of relay 4LSR, contact 28 of relay 3TB, contact 29 of switch 3, contact E8 of relay dRHSR closed in the reverse or right-hand position, upper winding [9 of relay lLER, contact of relay lRTR, and the back point of contact 2! of relay ZRGPR to terminal N. With relay 4LER thus energized, its contact 22 will remain open, and therefore lamp 4LE will remain unlighted.

With relay QHDR energized by current of reverse polarity, signal 6R will be operated to a caution position by a circuit passing from terminal B, through contact 39 of relay lI-IDR, contact 3i of relay fiHDR closed in the reverse or right-hand position, and the mechanism of signal 4R to terminal N.

If the leverman should clear signal 2R by moving'lever 2V to its r position and thereby eifecting energization of the upper winding of relay 2RHSR' through contact 8 of lever 2V in the r position, relay 2RGPR would become energized when signal 2B. is operated to the proceed position. The circuit for relay ZRGPR passes from terminal B, through contact 33 of signal 2R, and the winding of relay ZRGPR to terminal N. Relay ll-[DR would then become energized by current of normal polarity in a circuit which is the same as the circuit previously traced for this relay except that it includes the front points of contacts l6 and 2| of relay ZRGPR instead of the back points of these contacts. Signal 4R would then be operated to a proceed position by its circuit passing from terminal B, through contact of relay dl-IDR, contact 3| of relay AHDR. in its normal or left-hand position, and the mechanism of signal 4R to terminal N.

When the eastbound train enters section 3T, deenergizing relay 3TB, contact 28 of relay 3TB .will open the circuit traced for relays iLER and lI-IDR, causing these relays to be deenergized. With relay AHDR dcenergized, the operating circuits previously traced for relay 4R will be opened, causing signal 4R to again indicate stop.

With relay iLER deenergized, lamp ALE will again be lighted by its circuit previously traced. It follows that, although the upper winding of relay 4RHSR is energized, causing its contact 18' to be closed in the reverse or right-hand position,. lamp 411E willnow be lighted becauseof the traffic conditions between signals 4L and 4R, even though the trafiic conditions in the rear of signal 4L are not at this time such as to cause lamp GLE to be lighted.

When the train enters section 4R1, the circuit for relays LER and ll-[DR ,will be opened by contact 20 of relay lRTR at another point,

so that these relays will remain deenergized and lamp SLE will remain lighted. Similarly, lamp 4LE will remain lighted while the train moves through section IT, causing contact l5 of relay ITR to be opened.

Although I have herein shown and described only two forms of apparatus embodying my invention, 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 myinvention.

Having thus described my invention, what I claim is:

1. A lighting control arrangement for a given signal which is controlled to govern trafiic movements in a given direction over a given stretch of railway track which is also provided with an opposing signal located in advance of said given signal for governing traffic movements in the op posite direction over said given stretch of railway track, in which a control winding for said opposing signal is controlled by a circuit which is controlled by trafiic conditions in the rear of said iven signal and also by trafiic conditions between said given signal and said opposing signal, comprising, in combination, a lighting control relay for said given signal, manually operable means for selectively connecting said light-' ing control relay in said circuit in series with said control winding or connecting said lighting control relay in only the portion of said circuit which is controlled by traffic conditions in the rear of said given signal and which does not include said control winding, and a lighting circuit for said given signal controlled by said lighting control relay.

2. A lighting control arrangement for a given signal which is controlled to govern trafiic movements in a given direction over a given stretch of railway track which is also provided with an opposing signal located in advance of said given signal for governin trafiic movements in the opposite direction over said given stretch of railway track, in which a control winding for said opposing signal is provided with a control circuit which is controlled by manually controllable means and by traffic conditions in the rear of said given signal and also by traffic conditions between said given signal and said opposing signal, comprising, in combination, a lighting con trol relay for said given signal, means controlled by said manually controllable means for selectively controlling said lighting control relay by all of said control circuit for said opposing signal or by only the portion of said control circuit which is controlled by trafiic conditions in the rear of said given signal, and. a lighting circuit for said given signal controlled by said lighting control relay.

3. A lighting control arrangement for a given signal which is controlled to govern traffic movements in a given direction over a given stretch of railway track which is also provided with an opposing signal located in advance of said iven signal for governing trafiic movements in the opposite direction over said given stretch of railway track, in which a control winding for said opposing signal is provided with a control circuit which is controlled by traffic conditions in the rearof said given signal and also by trafiic conditions between said given signal and said opposing signal, comprising, in combination, lighting control means for said given signal, manually controllable means for selectively controlling said lighting control means in series with said control winding in said control circuit or by on y the portion of said control circuit which is controlled by traffic conditions in the rear of said given signal, and lighting means for said given signal controlled by said lighting control means.

4. A lighting control arrangement for a given signal which is controlled to govern trafiic movements in a given direction over a given stretch of railway track which is also provided with an opposing signal located in advance of said given signal for governing. trafilc movements in the opposite direction over said given stretch of railway track, in which said opposing signal is controlled by trairic conditions in the rear of said given signal and also by trafilc conditions between said given signal and said opposing signal, comprising, in combination, lighting control means for said given signal, manually controllable means for at times controlling said lighting control means in series with said opposing signal and for at other times controlling said lighting control means by only traffic conditions in the rear of said given signal, and lighting means for said given signal controlled by said lighting control means.

5. A lighting control arrangement for a given signal which is controlled to govern traffic movements in a given direction over a given stretch of railway track which is also provided with an opposing signal located in advance of said given signal for governing trafiic movements in the opposite direction over said given stretch of railway track, in which said opposing signal is controlled by traffic conditions in the rear of said given signal and also by traffic conditions between said signals, comprising, in combination, manually controllable means, for at times lighting said given signal in response to trafiic conditions in the rear of said given signal and for at other times lighting said given signal in response to said tramc conditions between said signals.

6. A lighting control arrangement for a, given signal which is controlled to govern trafiic movements in a given direction over a given stretch of railway track which is also provided with an opposing signal located in advance of said given signal for governing traflic movements in the opposite direction over said given stretch of railway track, in which a signal control circuit for said opposing signal is controlled by traffic conditions in the rear of said given signal and also by other conditions and by manually controllable means, comprising, in combination, a lighting control relay for said given signal included in said signal control circuit when said manually controllable means is conditioned for controlling said opposing signal to display a proceed indication but included in an approach lighting control circuit which includes only a portion of said signal control circuit which is controlled by traffic conditions in the rear of said given signal when said manually controllable means is conditioned to control said opposing signal to indicate stop, and a lighting circuit for said given signal controlled by said lighting control relay.

'7. In combination, a stretch of railway track, a given signal for governing trafiic movements in a given-direction over said stretch of track, an opposing signal in advance of said given signal for governing traffic movements in the opposite direction over said stretch of track, a control element for said opposing signal, a manually controllable device having a normal and a reverse position, a lighting control relay for said given signal having two control windings, a circuit controlled by traific conditions in the rear of said given signal and controlled by said manually controllable device in the normal position for energizing the two windings of said lighting control relay in series with each other, a second circuit controlled by trafiic conditions in the rear of said given signal and also controlled by other conditions and controlled by said manually controllable device in the reverse position for energizing one of the windings of said lighting control relay in series with said control element for said opposing signal, and lighting means for said given signal controlled by said lighting control relay.

8. In combination, a stretch of railway track, a given signal for governing trafiic movements in a given direction over said stretch of track, an opposing signal in advance of said given signal for governing traffic movements in the opposite direction over said stretch of track, a control element for said opposing signal, a manually controllable device having a normal and a reverse position, a lighting control relay for said given signal, a circuit controlled by traflic conditions in the rear of said given signal and also by traffic conditions between said signals and controlled by said manually controllable device in the reverse position for energizing said lighting control relay in series with said control element, a resistor, a second circuit including the portion of said first circuit which is controlled by trafiic conditions in the rear of said given signal and controlled by said manually controllable device in the normal position for energizing said lighting control relay in series with said resistor, and lighting means for said given signal controlled by said lighting control relay.

9. In combination, a stretch of railway track, a given signal for governing trafiic movements in a given direction over said stretch of track, an opposing signal in advance of said given signal for governing traffic movements in the opposite direction over said stretch of track, manually controllable means having a normal and a reverse position, a lighting control relay for said given signal, a control circuit for controlling said opposing signal in series with said lighting control relay controlled by said manually controllable means in said reverse position and controlled by trafiic conditions in the rear of said given signal and also controlled by traffic conditions on said stretch of track between said signals, a second control circuit controlled by said manually controllable means in said normal position including only the portion of said first control circuit which is controlled by traflic condition in the rear of said given signal for energizing said lighting control relay, and lighting means for said given signal controlled by said lighting control relay to be lighted when a train is approaching said given signal while said opposing signal is manually controlled to indicate stop and to be lighted when said opposingsignal is manually controlled to display a proceed indication but is controlled by trafiic conditions to indicate stop.

10. In combination, a stretch of railway track, a given signal for governing trafiic movements in a given direction over said stretch of track, an opposing signal in advance of said given signal for governing tr'affic movements in the opposite direction over said stretch of track, a lighting control relay for said given signal, signal control means for said opposing signal, and manually controllable means for at times controlling said lighting control relay in series with said signal control means through means responsive to traffic conditions in the rear of said given signal and through means responsive to traflic conditions between said signals and for at other times controlling only said lighting control relay through means responsive only to traific conditions in the rear of said given signal, and lighting means for said given signal controlled by said lighting control relay.

OTTO W. ROST.

No references cited.

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