US2554906A - Auxiliary train signal system - Google Patents

Description

y 1951 R. J. HERBOLD 2,554,906

AUXILIARY TRAIN SIGNAL SYSTEM Filed June 25, 1846- 52 Fgrl.

T 62 la 4 Z5 26 a2 a1 f1 W53 I 3nnentof Roberf J, Herbolcl witness CQH' FQ Herbevi coveJ i affomeg Patented May 29, 1951 OFFICE AUXILIARY TRAIN SIGNAL SYSTEM Robert J. Herbold, Denver, 0010., asslgnor to Lafayette M. Hughes, Denver, Colo.

Application June 25, 1946, Serial No. 679,298

Claims. (01. 246-177) This invention relates to railway signal apparahas and more particularly to apparatus which will warn the engineer that a red or danger signal has been set against his passage into the railway block.

Railroad accidents may result from the engineer passing a red light or a 'semaphorestop' signal, and this is often due to the signal being improperly located or'obscured by dense fog or storm conditions, or it may not'be seen by the engineer because of 'duties which' distract'his' attention. It is desirable to provide an audible or visual signal within the engine cab which gives the required indication of the condition of the track ahead, Many schemes have been proposed or tried, such as an "induction system associated with therails and an external source of power which duplicates the appearance of the block signals within the engine c'ab. Such Systems are, however, very expensive and are not infallible under the many operating conditions required, and they are employed simply as a double check on the engineer's vision of the outside signal. This system is particularly vulnerable to external conditions such as rain or snow, and it requires a high power consumption. Any supplemental signal system should not draw heavily on the existing storage batteries of the standard signal systern.

The primary object of this invention is to provide an apparatus which automatically warns the engineer within the locomotive cab that the track is not clear ahead and that a stop signal has been set against his entering the block.

A further object is to provide a warning signal construction which does not require excessive power consumption and which gives the required signal on the train only while the train is passing through a limited extent of travel.

A further object is to provide such a system in which the signal is rendered operative b the passage of the train and is inoperative at all other times. Other objects will be apparent in the following disclosure.

In accordance with my invention, I have provided a photronic signal system on the train which is activated by light governed in accordance with the setting of the track signal and wherein the light is in turn rendered eiiective by the approach of the train thereto.

Referring to the drawings:

Fig. 1 is a diagrammatic plan of the electrical circuits located near the track and showing the relationship of the signalling devices to the asso- 'ciated mechanism on. the loc mot ve; and

Fig. 2 is a diagram of the electrical circuits on the locomotive which provide the train signal.

The preferred embodiment of this invention comprises a photo sensitive cell mounted on the train and arranged to be activated b a light located near the track which shines only when the railway signal is set for danger, as is caused by raising a semaphore arm or energizing a red light or as desired, and only when the train is approaching the warning signal. The apparatus comprises essentially a light I ll arranged to throw a beam across the track towards a passing train which will activatea photosensitive cell I2 on the train, and the cell is in turn connected electrically to give a required signal or warning indication for the guidance of the engineer. The signal light I0 is suitably located relative to the railway semaphore or red and green light signal system 4|, such as near or on the signal tower as illustrated, or at a suitable distance therefrom. The light I 0, which may comprise an electric light bulb of suitable power and a reflector or condenser to concentrate the beam, is located at such an elevation that it will activate the photosensitive element I2 carried on the side of the train when the latter passes the light beam.

The photoelectric cell 12 may comprise a photoemissive tube of the type of the General Electric Argon gas filled PJ23 tube which is sensitive to the visible spectrum and infra red wave. In such a photoemissive tube, the anode may be a vertical wire and the cathode may comprise a sensitive coating of caesium on caesium oxide carried by a base of silver metal. Since such tubes may be not sufiiciently rugged to withstand the violent vibrations of a locomotive, I prefer to use a photoconductive type of cell, such as an Eby type R100, which has its electrical resistance decreased by light activation, and particularly by infra red rays. Such a photoconductive cell may have a ribbon of a suitable light activated resistance material, such as selenium, arranged between two electric terminals to provide the required conductivity of a current from a source of potential, such as a 6 volt or other low voltage battery, The cell may be connected in series with a suitable sensitive relay arranged to control a secondary load or signal circuit. The photosensitive cell l2 (Fig. 2) may be mounted within an opaque casing l4 having a long projecting tube l5 adapted to receive only a narrow pencil light or ra from the lamp In so that the sensitive element may not be activated by ambient or extraneous light.

The light receiving and signalling system on .the locomotive or train may be of various constructions for the purpose of giving the required signal. The simplified form shown in Fig. 2 involves the Eby photoelectric resistance cell l2 connected in series with a 6 volt battery it and a variable resistance ll of about 25 ohms and with the solenoid of a rela l8 arranged to operate a switch I9 against the pressure of a spring 20 and thus close the circuit through a battery 2| with an electric bell 22 and a signal light 23 arranged in series with the battery. Many con structions may be employed to give the required signal to the engineer, whether audible or visual. The system may be such that the signal 23 has lights arranged vertically as a clear track semaphore signal at all times unless the photocell l2 clear. The holding rela may be of many types of construction, such as the standard dash-pot type in which the movement of a piston is delayed by fluid flowing under spring pressure through a small orifice. Operation of the solenoid 33 causes the piston to move against spring pressure to a is activated, in which case the relay throws a circuit to show a horizontal red light signal; or a steady white light may be interrupted by operation of the relay and a red light thrown on.

It is desirable that the strong light in mounted on the ground, which activates the photoelectric cell l2 on the locomotive, be lighted only while the signal is required; i. e., when the train is passing. For this purpose, I propose that a device on the engine serve to connect the lamp Hi to its source (if power only while the engine is passing from an initial light exciter position to one where the photoelement l2 may be activated. Various types of mechanical switches may be placed near the track for operation by a lever arm moved down by the wheels of the locomotive; but such constructions are subject to interference by snow or have other disadvantages. I, therefore, prefer to employ a photoelectric device which is excited by a beacon light carried by the locomotive.

This beacon system may comprise an electric light 25 carried on the engine or train in a suit able concave reflector 2 6, or associated with a condenser lens to concentrate the light beam. The lamp 25 need not have a very high candle power and it may be operated continuously by a series connection with the battery l9, as illustrated in Fig. 2. This battery may be replaced by a small generator on the locomotive, or the power may be derived from the train electrical system. Mounted on the ground at a suitable distance in advance of the signal light II! (which is to be duplicated at both sides thereof) is a photoelectric element 30 arranged to control the light I0 and cause it to shine while the engine is moving past. This trackside phototube 30 may be of any desired type, such as a photoemissive tube, as above described, or a Weston photovoltaic cell. If a photoconductive selenium cell or a photoemissive tube is employed, then a suitable battery 3| is arranged in the circuit that connects the photoelement with a suitable amplifier 32, The amplifier 32 controls a relay solenoid 33 which operates a make-and-break switch 34 that governs another circuit to connect the battery 35 with the light Hi.

It is required that the light I0 shine for several seconds or for a delayed period of time after the photoelectric element 30 has been activated and has completed closure of the switch 34, or until the photoelement .l2 reaches the line of light from lamp H1 at the signal tower. For this purpose I may employ a holding or delay relay 4!! in association with a further relay switch system which permits the light In to shine only if the standard railway tower signal at 4| is red or otherwise indicates that the track ahead is not position where the spring thereafter causes the piston to move slowly while the fiuid is escaping and the circuit remains closed until the piston has reached its initial open circuit position.

The construction of the relay 40, as illustrated, comprises a solenoid 42 arranged to move a switch arm 43 against the action of a spring 44 and make the circuit through battery 35 with the lamp Ill. The delay feature of this construction, which may be of standard type, comprises in general a bi-metal latch 45 which springs into place and holds the switch arm 43 locked in position until a heater coil 45 surrounding the bimetal latch expands the latch metals difierentially enough to spring the latch away from the switch arm and allow the spring 44 to break the connection. A supplemental circuit including a variable resistance 41 is arranged to pass current through the heater coil of the latch while the circuit is closed. A suitable resistance 65 in the light circuit insures a proper division of the current between the light and heater coil circuits. It will be understood that any suitable delay mechanism may be employed for this general purpose, provided it will hold the lamp I0 lighted for such period of time as is required for the train to pass from the position of activating the phototube 30 to that of having its phototube l2 activated by the light 10. After the proper signal has been given to the engineer in the cab, the time delay mechanism at the signal tower on the ground is no longer needed. It is also feasible to place a holding relay in the circuit of the electric light 23 and bell 22 in the engine cab, so that the signal will remain operative for considerable time. I may, however, provide a latch 48 in the engine cab which holds the connection of the switch I9 closed until the engineer manually releases the same. This simplified construction, as illustrated, ma however be replaced by more elaborate or desired mechanism which will effect the required purposes.

The circuit to lamp It] should be made only if the red or danger signal is showing at the switch tower 4!. This is accomplished by a supplemental relay switch in the holding relay system. As shown, the red signal light 50 and the green signal light 5| are mounted in series with a battery 52 for actuation of either light as required by the railway signal system. Suitable switches and controls will be provided to give the required red or green signal at the tower. If the green signal G is on, then a circuit is made with the lamp 5| and battery 52 through the wires 53 and the switch arm 55 that is held against the relay contact wire 56 by spring 57. This breaks the circuit between contact 58 and the switch arm 55 which is also connected through battery 56 and switch 34 with the solenoid 42 of the holding relay 40. Therefore, any activation of the cell 30 by the exciter lamp 25 on the locomotive will be ineffective to turn on lamp Hi.

When the red light 50 is to be displayed at the signal tower, the operator throws a switch 60 in a supplemental system including a solenoid 5i and a battery 63, thus energizing the solenoid and pulling down the relay armature 55, This breaks the green light circuit through the armature, 55 and contact 56 and makes a circuit through the'c'ontact 62 and the battery 52 to turn On-the-red light 50. At the same time a connection is made between contact 58 and the arm- 55,which is in circuit with the winding of the relay solenoid 42, so that when the relay 3 4 has been closed by activation of cell 30 by light on the train a circuit is made through battery 66- which closes the switch 43 and turns on the trackside'light 3. Thus, the two relay control devices 6 l 55 and. 33, 34 which are governed respectively by setting the track signal and by activating the track-side element act in series to insure that the light Ill can be energized only when the red signal 50 has been set and the train light 25 is passing the element 30. Hence, the engine cab signal can be given only under these two precedent conditions. Also, this lighting of lamp l0 lasts only while the relay switch 40 permits it. Hence there is only a very small consumption of power, and a comparatively high wattage lamp [0 may be used without drawing heavily on the battery 35. Various other advantages are inherent in the system. For example, the construction on the engine is very rugged and will withstand severe vibrations. The apparatus mounted on the ground or at the tower may be made as delicate as desired, since it is not subject to vibrations.

Since the photo elements are sensitive to infra red light which passes readily through rain, fog and snow, the signals will be received by the locomotive engineer within the cab even if he cannot see the signal on the outside. Various expedients may be adopted to prevent the ambient or outside light from interfering with the signal system.

The operation of this auxiliary train signal apparatus gives a warning on the train of a signal that has been set by the standard railway track signalling semaphores or red and green light system. The preferred construction comprises a photo element on the train and apparatus, such as a signal bell or light, which is governed by the photo element, so that the apparatus is energized when the element is activated by a track light arranged near the track and close to the passing train and at such a height and direction of pointing that a beam therefrom will illuminate the photo element. The track light is maintained in an oil condition, except when required to give the train signal, because its power circuit can be completed only when a predetermined railway track signal has been set. Changing the track signal to red closes a switch in a power circuit which remains in that condition during the entire period that this red signal is displayed. The light It), however, it not energized by its power circuit until a second switch is closed, and that switch is governed by the passing train. This is preferably effected by the photocell 30 arranged near the track and in advance of the track light It, relative to the direction of train travel. When this cell 30 is activated by a light 25 on the passing train, it serves through its amplifier and a supplemental relay system 34 to actuate a holding relay 40, provided the switch 55, 58, that is controlled by manipulation of the track light system, has been previously closed. This completes an electrical circuit for supplying power to the track light [0, thus energizing the photo element [2 when the latter reaches the ppsition of passing that track light, and giving the danger warning on the train. That train signal may be maintained in an on condition by a holding relay or by any other suitable device for a reasonable length of time.

It will be appreciated that the electrical circuits and associated apparatus may be changed materially, provided the apparatus operates in accordance with the principles above set forth. Hence the above description is to be interpreted as describing those principles and a preferred embodiment of the invention and not as imposing limitations on the claims appended hereto.

I claim:

1. In combination with a railway track signal and means for setting it, an auxiliary train signalling apparatus for giving a warning of the signal set against a train comprising a photosensitive element and an electrical signalling device governed thereby which are mounted on the train, a trackside light fixed relative to the track signal for activating said photo element as the latter passes it, a normally broken electrical power circuit for energizing the trackside light, a trackside photosensitive element located in advance of the trackside light relative to the train travel, means including a light on the train for activating said trackside element as the train passes it, and normally inoperative electrical apparatus including two control devices governed respectively by activation of the trackside element and by setting the track signal which completes said power circuit for energizing the trackside light after the track signal has been set and the train light has activated the trackside element.

2. Apparatus according to claim 1 comprising a releasable time delay device controlling the trackside light circuit for prolonging the period during which the trackside light is energized and after the trackside photosensitive element ceases to be activated.

3. Apparatus according to claim 1 comprising a releasable holding device on the train which maintains the electrical signalling apparatus effective to prolong the warning signal after the photosensitive element on the train ceases to be activated.

4. In combination with a railway track signal light, an energizable circuit therefor and controllable means for energizing the circuit and displaying the light, an auxiliary train signalling apparatus for warning of the displayed light comprising a photosensitive element and a signalling device governed thereby which are mounted on the train, a trackside light fixed relative to the signal light for activating the train element as the latter passes the light, a power circuit for the trackside light including a switch which is biased towards an open position, a time delay device effective to releasably hold the switch closed for a given period of time, a solenoid for closing said biased switch and rendering the time delay device elfective, a trackside photosensitive element fixed in ad- Vance of the trackside light, a light on the train to activate the trackside element when passing it, a normally open relay switch which is closed by activation of the trackside element, a second normally open relay switch which is closed when the track signal light circuit is energized, and an electrical circuit connecting said relay switches in series with said solenoid, so that the train signalling device can be rendered operative by the trackside light only while said controllable means causes the track signal light circuit to be energized and the track signal light to be displayed and after the train light has activated the trackside element.

5. Apparatus according to claim 4 comprising an electrically operated signalling device on the train, a power circuit therefor including a switch which is biased towards an open position, a releasable device for holding the switch closed, and a solenoid governed by activation of the photosensitive element which closes the switch and renders said releasable device efiective to hold the switch closed and prolong the signal after the time of activation of said element. ROBERT J. HERBOLD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS France Oct. 1, 1906

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