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Publication numberUS1610692 A
Publication typeGrant
Publication dateDec 14, 1926
Filing dateMay 9, 1921
Priority dateMay 9, 1921
Publication numberUS 1610692 A, US 1610692A, US-A-1610692, US1610692 A, US1610692A
InventorsLogwood Charles V
Original AssigneeLee De Forest
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Railroad signaling system
US 1610692 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Dec. 14,1926. 1510592 I C. V. LOGWOOD RAILROAD SIGNALING SYSTEM Filed May 9. 192 1 2 Sheets-Sheet 1 Dec. 14, 1926, 1,510,692

C. V. LOGWOOD RAILROAD SIGNALING SYSTEM Filed Mair 9, 1921 2 Sheets-Sheet 2 INVENTOR limb/ V", ATTORNEYs E Patented l)ec. 14, 1926.




This im'ention relates to lug systems,


Application filed May 9, 1921.

railroad signaland is particularly directed to the use of the three electrode audion when used as a source of continuous oscillation, 5 called in the art the oscillion in such a system.

The object of the invention is to provide a signaling system which is simple in structure, installation and in operation and economical of manufacture.-

maintenance, efficient A further object of the invention is to provide a railroad signaling system which will prevent any type of train from colliding with another train on the same track, whether the railroad is of a single or a double track type.

A further object of the invention is to provide a system audion or oscillion is employed, the operation of which oscillion is controlled by the presence or absence of a train on track within a the same prescribed distance.

A further ob ect of the invention is to apply high frequency currents in connection with railroad signaling work.

A further object of the invention is to apply an oscillion and its associated circuits controlled by same track Within a the presence of a train on the prescribed area for controlling any type of apparatus such as a signaling indicating device, the application of brakes or such accompl sh any other type of apparatus to desired purpose.

Further objects of the invention will appear more fully hereinafter.

The invention consists construction,

substantially in the combination, location and relative arrangement of parts and the method of utilizing the same, all as will be'more fully hereinafter set forth, as shown by the accompanying drawings and finally pointed out in the appended claims.

Referring to the drawings,

Fig. 1 illustrates a bodying my invention.

signaling system em Fig. 2 shows diagrammatically and in plan a stationary part of the signaling system.

Fig. 3 shows diagrammatically an elevation of means employed for establishing electri: al communication between the moving train or member and the track.

Fig. 4 is a slightly modified arrangement siniilarto and illustrating the portion of the invention shown in Figure 2.


5 and 6 show two modified arrangewherein an oscillating such for example wireless art, which coil or loop is formed cuit from oscillating. If

Serial No. 467,864.

ments for accomplishing the purpose of my invention.

The same part is designated by the same reference character wherever it occurs throughout the several views.

lVhile I have shown and will now describe my invention, as specifically applied to railroad signaling systems, I wish it to be understood that 'in its broadest scope my invention consists in applying high frequency alternating currents to uses in recording or indicating the relative distances between two bodies either both moving or one stationary and the other moving, which distances are controllable or may be predetermined. Theiefore, while'such illustration of the application of the invention herein involved atl'ords one specific use, which has marked advantages over systems employed in the railroad signaling art, I do not desire to be limited or restricted thereto.

It is known that if we have persistent high frequency alternating currents in a closed oscillating circuit supplied-from a source which is not too powerful, 'and'if a closed loop or coil corresponding to a loop antenna, as is used in the radio or of one or several turns, isbrought up close to the inductance coil of the oscillatin circuit, so that these two coils are parall el or approximately parallel to each other, then the second circuit, i. e. the coiled loop circuit, will absorb a large percentage of the ,oscillating current energy from the oscillating circuit. If the coupling of the two coils be'made sufliciently close, the damping thus introduced into the oscillating circuit by the presence of the coil or absorbing circuit, is sufficient to completely or nearly completely prevent the first or oscillating or energy cirthis first circuit be supplied with high frequency energy from say an oscillating audion or oscillion in the usual manner well recognized in the art, i. e. by supplying suitable circuit connections for the oscillion including a source of high potential between its plate and filament electrodes, a very great change in the amount of the voltage or B battery supply in the plate filament circuit of the oscillion will occur when the oscillating or first circuit connected to said oscillion is put into a nonoscillating condition. Therefore, if aconsiderable proportion of the inductance of this energy circuit be made in the form of a large area coil, even if of comparatively few turns, a similar coil short circuited either upon itself, or through a suitable condenser, need only be brought within a few inches or even a foot or two from the first coil in order to absorb sufficient of the high frequency energy of the first coil to cause such large percentage change in the B current to the oscillion to thereby operate very positively any suitable indicating device located in the circuit of the B battery source.

Such an indicating device may be a direct current relay preferably consisting of an iron cored coil of a large number of turns with a moving arn'lature arranged to make or break an auxiliary circuit, in which may be connected a buzzer, .bell or other suitable signaling means, or this circuit may control any safety appliance such as the brakes, steam throttle (in the event it is used on a steam railroad), the mot-or controller (in the event it is used on" an electric railroad), or such other or similar device or devices, which it may be desired to control to accomplish any desired purpose.

As an alternative to relay in the B voltage circuit, it is obvious that one of the hotwire ammeter type may be employed, the fine wire of which is then located in the high frequency circuit as distinguished from the direct current supply cir' cuit, and the needle of the hot wire circuit so arranged as to close a secondary auxiliary circuit, when the oscillating currents cease in the high frequency or energv circuit.

If the absorbing circuit, instead of being a simple closed coil of one or several turns, includes an inductance coil and a condenser in series, then it will, generally speaking, be necessary to tune this circuit to resonance with the frequency of the oscillating circuit before it will absorb from the oscillating circuit any considerable proportion of its high frequency energy, even though the two coils be parallel and brought close together. Vhen thus in resonance, however, the separation between the coils can be made much wider and still effect the desired absorption when the absorbing circuit is merely a closed coil, and in addition a wide degree of selectivity can be obtained, so that if several such absorbing circuits be successively brought into proximity .to the energy coil, only that one which is closely in resonance with the energy or oscillating circuit will absorb an appreciable amount of energy therefrom.

If now such an oscillating circuit and system as I have described be located on a travelling vehicle, such, for example, as a railroad locomotive or tender or on a car, and the inductance coil thereof be a large square, rectangle, or a circle in shape, and located horizontally near the earth or track-bed, yet

the above describedhigh enough to clear all obstacles in passing; and if the absorbing coil be approximately of the same shape and size and fixed to the track-bed, either closed or open, then as the vehicle or travelling coil passes over the fixed or absorbing coil, even at a very high velocity, its passage thereover will be at once indicated by the signaling instrument I have deScribed loCa-ted in the oscillatory circuit of the oscillion, which is, as above stated,

carried by the vehicle. This, of course, will occur provided that the absorbing coil be either; closed on itself or form part of a closed oscillating circuit tuned to the frequency of the passing or travelling oscillating circuit. Thus, if a switch which closes this absorbing circuit be closed, a signal will be made in the cab or vehicle, as above described, or some operation will be effected thereby, whereas if said switch be open no signal will be made.

Therefore, while I do not desire to be limited or restricted in this respect, it will be apparent that one application of the invention herein involved will be to prevent a train or car, through negligence, oversight or accident, from passing by a signal set against the progress of the car, train or the lil;e. Thus, if this switch just mentioned be operated by a track side semaphore Sig-- nal, when the latter is set at danger or stop, the engine driver or motorman will be apprised of the fact by the operation of the signaling device in his cab or the application of the brakes or in such manner as the invention hereinv is utilized, even if he has neglected to observe the passing semaphore signal. If, however, the semaphore signal be set to its clear position, or is not set against his progress, the cab signal will not be operated.

One of the great advantages of my invention resides in the fact that any failure of the travelling portion of my system,such as an open circuit in the high frequency travelling system, or burning out of the oscillion bulb or of any of them in the event more than one is used, will result in the cessation of oscillations and the danger signal will be given to the engineer or 'motorman.

Referring now to the drawings, and particularly to Fig. 1, I show at 1 an oscillion consisting of the usualvacuum bulb having associated therewith and preferably contained therein the usual filament grid and plate electrodes 2, 3 and 4 respectively. Associated with the oscillion. 1 are suitable cir' cuits to render the oscillion a source of high frequency oscillation.

While I do not desire to be limited or restricted to any particular type of circuit for thus producing high frequency oscillation, as it is well recognized particularly in the radio art that many circuits will ac-- complish this, I have shown one circuit Inc wherein the. plate electrode is connected through a condenser and switch 6 to the filament electrode In this circuit is enclosed the B voltage battery source 7, preferably a 1). C. generator, and a relay 81. The switch 6 is provided to enable putting into the circuit thus described one or the other of a number of condensers 8 which are preferably of the adjustable type to alford proper tuning. 'Another by-path circuit is provided in this arrangement and indicated at? 9 between the fixed and variable eondensers and the filament as clearly shown. The grid electrode 3 is connected to the plate filament circuit through a blocking con-' denser 10 shunted by a high resistance 11 in the usual manner and for a purpose well understood in the-audion and oscillion art. The oscillations set up by this system are drawn from the plate' filament circuit through what, I will term the primary circuit which includes an inductance 12 connected to the plate at one end and formed into the primary loop 13 and leading thence to the filament 2. The loop 1 37. may be carried for example as at 14, see Fig. 3) at the bottom or undersurface of the car, engine or thelike. I \Vhat I have hereinbefore referred to as 'the secondary or absorbing circuit is shown at 15, which consists of a similarly shaped loop terminating at one end in condensers 16 any one of which may be included in circuit by means of a switch 17, which switch is connected to aterminah'for example one part of a knife switch 18, the other end of the absorbing coil terminating in the blade 1.) of the knife switch which is, for example, pivotally mounted as at 20 at a point intermediate its ends, one of which is connected by a series of levers and cranks 21 to be controlled by the movement of a semaphore signal 22.

Thus it will be seen that. assuming that the switch 17 has been positioned on a suitable condenser to afford the desired reso-.

nance, which, when once adjusted, remains the same, when the semaphore 22 lS 'l1'l its lower or track clear position, as shown by dotted lines in Fig. 1, the knife switch 19 will be open. and in consequence the absorb- 1ng loop 15 inoperative. When, however,

the semaphore is in its raised position, as

semaphore stand diagrammatically illustrated at 22. and the loop 15 may be either placed in the open air or. where weather conditions make it preferable, enclosed in a boxjor other type of container, as illustrated at 23 in Fig. 3, which, due to the fact that high frequency pulsating currents are being employed, does not impair the operation of the system. Thus it will be seen that, as hereinbefore more fully pointed out,

the oscillations passing through the energy leads 83 and 84 of an otherwise closed cir- I cuit, which upon such circuit establishment renders operative the apparatus or device to be operated, for example, the buzzer or hell 85. It is to be understood, of course. that whatever current is normally flowing through coil 81 is insufficient to cause the same to lift the armature 82.

As hereinbefore set forth, in place of the relay arrangement 81 to 85 inclusive, the operation of the signal device or the notice to the engineer or motorman by the oscillatory circuit 13 may be detected for example by means of the hot wire ammeter 2-l included in the oscillatory circuit rather than in the direct current circuit in which, of course, the relay 81 is located. I

Fig. 4 diagrammatically illustrates two phases of my invention, It will be obvious that by increasing the size of the loops, a sufficient area can with perfect safety be ob-- tained which will insure the operation of the system irrespective of the speed of the train carrying the oscillating circuit. However, where it is desired to have small sized loops and at the same time to insure a proper operation, a series of absorbing loops 15, 15", and 15 'may be employed, thus insuring, irrespective of the speed of the vehicle carrying the oscillating circuit, the necessary absorption to operate the auxiliary circuit. Similarly, for-example, in the case of a one track system, the various loops 15, 15 and 15* may be attuned to different frequencies, so that the signal shall be operated on certain passing vehicles but not on others, according to the frequency of the oscillations generated by the oscillion on the receiving vehicles, or some means may be provided for automatically tuning the condensers in the absorbing circuit, by and in accordance with the particular occasion; for example as shown in Fig. 1, the switch 17 may be controlled by the semaphore, so that either of the condensers 16 will be put in circuit therewith by the semaphore, when it is set against an east bound train and the other by the semaphore or track switch when set against a west bound train. Of course, it is obvious that the oscillations produced by the oscillion on the travelling vehicle can be controlled 'as'to frequency in any suitable manner.

\Vhile I have'described an oscillion as a source of pulsating currents of high frequency and as being at the present time the mostefiicient device for this purpose, I do not desire to be limited or restricted thereto as any suitable source for producing the high frequency oscillations may equally well be employed.

Results similar tothe foregoing may be had if instead of utilizing two inductance coils, that is the coil of the oscillatory circuit and the absorbing coil hereinbefore described, I utilize the two armatures of one condenser or preferably of two condensers in series, so as to greatly unbalance the normally oscillating circuit, thus so increasing the capacity therein that it becomes a very weak oscillator or ceases to oscillate altogether. Fig. 5 shows such an arrangement. Large horizontal plates 56 and 57 are carried underneath the vehicle, and plates 58 and 59 are on the road-bed and controlled by the semaphore levers 21, so that when the semaphore is set to danger the knife switch 19 places the plates 58 and 59 in series with each other, thereby effectively short cireuiting the normal condenser in the oscillating circuit, in the, manner which will be clearly understood with .reference to the description in Fig. 1. Instead of causing the energy circuit to cease oscillating as by the manner shown in connection with Fig. 5, this momentary increase of capacity can be used to so alter the normal wave length of the oscillating circuit that a large change in deflection is produced in a hot Wire signal control device in a fixed tuned circuit which is always closely associated with the energy circuit. Such a hot wire ammeter device is shown at 60 included in the circuit with the coil 61 inductively related with the coil 12 of the oscillatory cir-. cuit. This hot wire relay will then close the signaling circuit and thereby indicate that two track side condenser plates have been connected together by means of the. semaphore switch.

Fig. 6 shows an arrangement somewhat similar to Fig. 5. In this arrangement only one track side condenser plate is employed, which plate 58 is kept well insulated from the ground, except by way of the lead to the terminal 18 controlled by the knife switch 19 which in turn is controlled by the semaphore lever arrangement 21 as hereinbefore described. The other plate 56 of this condenser is suspended by insulators from the bottom of the travelling vehicle, so as to clear the plate 58 by a few inches. The plate 56 is permanently connected as shown to the high voltage part of the oscillating circuit of the oscillion 1, while the low voltage part of the said circuit (i. e. the filament side) is permanently grounded, for example is connected to the truck of the car as illustrated bythe wire 71. Now, when the knife switch 19 is closed on the terminal 18 and plate 56 passes over the plate 58, the condenser thus affected is in parallel with the condenser 72 of the oscillating circuit. The combined capacities of these two condensers thus obtained are large enough to cause the oscillating circuit to become non-oscillatory and to thereby operate the signal relay 81 as above described, It will be apparent that the condensers 56, 58 can be connected across any suitable part of the oscillatory circuit desired to produce a large change in the oscillating characteristics of the said circuit. that being the purpose in the arrangement thus described. 1

Many other modifications and changes in details will readily occur to those skilled in the art without departing from the spirit and scope of my invention as defined in the claims, and I, therefore, desire to have the foregoing illustrations and descriptions thereof regarded in an illustrative sense rather than in a limiting sense.

It will also be apparent that while I have described my invention as used in connection with the ordinary semaphore system, it Will readily be apparent to those skilled in the art that the system of my invention may be employed as a substitute for the semaphore system and used wholly independently thereof.

But having now set forth the objects and nature of my invention, and having shown and described various arrangements e1n bodying the principles thereof, what I claim as new and useful, and of my own invention, and desire to secure by Letters Patent, 1s:

1. A system for the operation of a control device, comprising, in combination, a source of high frequency oscillations, an electrical receiving apparatus selectively responsive to said oscillations, and arranged and adapted to actuate said control device, and a stationary conducting means in electrostatic connection with said source and receiving apparatus, and adapted to serve as a tuning element in the circuit thereof by the relative movement thereof.

2. A system for controlling the operation of a vehicle, comprising, in combination, a source of high frequency oscillations, an electrical receiving apparatus mounted upon a vehicle and selectively responsive to said oscillations and adapted to actuate a brake control device upon said vehicle, and a stationary electrical conducting means electrically coupled to said source and receiving apparatus and adapted to serve as a tuning element of the circuit thereof by the movement of said vehicle.

In testimony whereof I have hereunto set my hand on this 5" day of May, A. D. 1921.



Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2460511 *May 27, 1943Feb 1, 1949Link Aviation IncAutomatic radio signaling means for aviation trainers
US2609488 *Sep 4, 1946Sep 2, 1952Burns Ltd JMeans for signaling on railways
US2768286 *Dec 13, 1951Oct 23, 1956Gen Railway Signal CoInductive train brake control system
US3184730 *Jul 30, 1962May 18, 1965Irish Robert HIntrusion detection system
US5030886 *May 25, 1990Jul 9, 1991Union Switch & Signal Inc.Self-checking circuit arrangement for operation of a searchlight signal
US5184694 *May 8, 1991Feb 9, 1993Pacer Manufacturing Co., Inc.Remote control system for go kart track and go kart conversion kit
US6084533 *Feb 26, 1998Jul 4, 2000New Mexico State University Technology Transfer CorporationDirectional traffic sensor system
U.S. Classification246/63.00A, 246/8, 246/30, 340/941, 180/167, 340/907
International ClassificationB61L3/12, B61L3/00
Cooperative ClassificationB61L3/121
European ClassificationB61L3/12A