US2272107A - Railway traffic controlling apparatus - Google Patents

Description

Feb. 3, 1942. P. N. BOSSART RAILWAY TRAFFIC CONTROLLING APPARATUS 3 Sheets-Sheet 1 Filed Jan. 15, 1941 Zim'n Carmbd zrrezzzSoar'aa IN ENTOR HIS ATTORNEY Feb. 3, 1942.

P. N. BOSSART RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 15', 1941 3 Sheets-Sheet 2 INVENTOR PaulZVrrarz- [[15 ATTORNEY Feb. 3, 1942. P. N. BOSS'ART RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 15, 1941 3 Sheets-Sheet 5 Fl- [lilili INVENTOR Paul N Jzrazz.

15 ATTORNEY Patented Feb. 3, 1942 UNITED, STAT RAILWAY TRAFFIC CONTROLLING I APPARATUS v Paul N. Bossart; (lheswicky, Pa., assignor to' The Union Switch & Signal Company, -Pa., a corporationof Pennsylvania,

Swissvale,

Application January 13, 1941, Serial No. 374,268

' 14 Claims. 1(01. 246 -63) My invention relates to railway traffic controlling apparatus, and more particularly to train carried train control apparatus responsive to current is suppliedto the track rails of-a track section through apparatus controlled by traflic conditions in advance of the section and the code 7 rates of 180, 120 and "75 interruptions per minute are those generally used to reflect clear, approach medium and approach traffic conditions, respectively. In two-block three-indicationsysterms the code rates of 180 and '75 only are re-.

quired. Inductors are mount'edon a trainin inductive relation to the track rails to inductively pick up energy during each on period of the coded current and hence thereceived energy has the same frequency and code rate as the rail current. The train is'providedfwith train control apparatus including a filter,'an amplifier, a

code following relay and decoding relays, and

such train carried apparatus has been standard ized and a great manyare now in service. The apparatus is housed in a suitable weatherproof box or case mounted on the train. -The exterofcourse that direct current would provide the nal circuits are connected tothe proper local circuits withinthe box at terminal posts placed at a suitable location in the box. The outside source of supply which is ordinarily the usual 32 volt train carried generator or battery, and the i inductors are connected to distinctive properly identified terminals. A filter is included in the apparatus and is interposed between thetermie nals to which the inductorsare connected and the amplifier and this filter are tuned sharply at 100 cycles per second or some preselected frequency of that order so thatonly energy corre.-

sponding to the coded track rail current is passed to the amplifier. The [amplifier consists ordinarily of two stages of amplification each stage of which includes an electron tube and associated circuits. The amplifier and its associated circuits are desi ned for the use of alternatingcurrent of the frequency of the order of .100 cycles per second. The master code following relay and decoding transformer are built intothe amplifier unit and the master code following relay pole changes the supply of direct current to the primary winding of the decoding transformer, to the secondary winding of which transformer the frequency alternating current for long track secv decoding means 'is' connected. Such decoding means comprises reactors and condensers neces-' saryto-tunethe decoding relay circuits to'frequencies corresponding to the respective code rates of the track circuit current. That'is th e decodingrelay-circuits are'tuned to frequencies corresponding to 180; 120 and '75 code rates. As'

stated hereinbefore such train carriedtrain control equipment hasbeen standardized and many are in use. r

Track sections of the order of 11,000 feet in length have been proposedfor railway signaling systems in order to adjust'the signal system to the required train braking distance for high train speeds. A track circuit for an 11,000 foot track section" may not provide effective broken rail protection whenalternating-current of 100 cycles ,is' used. In rder to assure effective broken railprotection for a track circuit of 1l,000' feet in length it is necessary to use alternating current of 'a relatively low frequency,- that is, an alternating current'of a frequency of the order of 20 cycles per second or less must be used to provide effectivebroken rail protection for track 7 circuits 11,000 feetin length. It is to be noted,

highest'degree of broken rail protection. When energy is inductively transferred between the track rails and train. carried inductors'the frequency of the current determines 'in, part the,

magnitude of the energy transferred.

In'view' of the above cited standardized appa ratusand the necessity of using. a relatively low tions, a feature of my invention is the provision of railway traiiic controlling apparatus incorporating novel means wherewith' alternating current of the frequency of the order of 20 cycles per second effectively influences standardftrain I carriedtrain'control apparatus designed for re- 7 sponse to alternating current of the frequency of the order or 100' cycles per second.

Another feature of my invention is the provision of train carried train control apparatus incorporating novel means for converting coded alternating current of a relatively low frequency into coded alternating current of a, relatively highfrequency with the coding of the low frequency current maintained for the high: frequency current. I

I Again, a feature of my invention is the provision of a'novel adapter which when introduced between present standardizedtrain carried inductors and their respective terminal posts within th usual'equipment'box, practically no changes are required for eifectively operating the standard amplifier and associated circuits by a preselected relatively low frequency alternating current supplied to the track rails.

Still another feature of my invention is the provison of a novel and improved adapter comprising a frequency changer and amplifier together with a switching means wherewith one position of the switching means render the adapter active and connects it between the inductors and the respective terminals of the standard equipment box, and another position of the switching means renders the adapter inactive and the inductors are connected directly to the respective terminals of the equipment box so that such train carried train control apparatus can be used with the present day track circuits provided with alternating current of the order of 100 cycles per second.

The above features of my invention, as Well as other advantages thereof which will become apparent as the specification progresses, are attained according to my invention by providing a suitable box or case which can be readily installed adjacent the standard equipment box and mounting in this additional box a four-pole double-throw switch and an adapter, and which adapter includes a frequency changer and an amplifier. The present wire from the inductors to the respective equipment box terminal FT is moved over onto a present spare terminal which in the instant case is designated terminal FTI. A wire from terminal FTI together with four wires from terminals B32, N32, TC and FT of the present equipment box are carried through the four-pole double-throw switch in such a manner that in one positon of the switch the power supply terminals B32 and N32 are disconnected from the adapter and the wire to the F'Il terminal is connected to the wire from the FT terminal with the result that the adapter is inactive and the inductors are connected directly to the standard equipment with the net result that the apparatus is conditioned for use with present day 100 cycle alternating current. The other position of the switch applies power from the B32 and N32 terminals to the adapter and the adapter is energized and made active, the wire from terminal FTI is connected to the input side of the adapter and the output side of the adapter is connected to the wire to terminal FT with the result the adapter is interposed between the train carried inductors and the standard equipment and converts coded alternating current of a preselected low frequency to coded alternating current of a frequency of the order of 100 cycles, which latter current is applied to the present standard equipment, the coding of the low frequency alternating current being reproduced in the 100 cycle alternating current.

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

In the accompanying drawings, Figs. 1, 2 and 3 are diagrammatic views showing three different forms of apparatus each of which embodies my invention. In the different views like reference characters are used to designate similar parts.

Referring to Fig. 1, the reference characters la and l b designate the track rails of a railway over which trafiic normally moves in the direction indicated by an arrow and which rails are formed by the usual insulated rail joints into a track section D-E which section may be one section of a series of consecutive sections of a signal system. I shall assume for the purpose of illustration that section D-E is of a length of the order of 11,000 feet to provide satisfactory train braking distance for high train speeds. The section D-E is provided with a track circuit including a source of alternating current connected across the rails at the exit end of the section and a track relay connected across the rails at the entrance end of the section. The immediate source of current for the track circuit of section DE is a track transformer TD whose secondary winding 2 is connected across rails la and lb at exit end D over wires 3 and 4 with a current limiting impedance 5 preferably interposed in wire 3. A primary winding 6 of transformer TD is connected to a source of alternating current such as a generator G over any one of several different circuits which circuits include contacts of a control relay SA, contacts of an approach control relay VD and contacts of a code transmitter or coder CT. The generator G would be driven by any suitable means not shown and would deliver current at a preselected frequency and in order to better understand the invention I shall assume generator G delivers current of a frequency of 23 cycles per second. It will be understood, of course, that my invention is not limited to the use of a 23 cycle alternating current and any relatively low frequency of the order of 20 cycles or less may be used, it having been found as stated hereinbefore, that alternating current of the order of 20 cycles per second or less gives satisfactory broken rail protection for a track circuit 11,000 feet in length. It is also to be understood that my invention is not limited to a track section 11,000 feet in length, but such length is used for the purpose of illustration. It is apparent that generator G may be located at some central power station and current transmitted therefrom to the track section DE over a transmission line.

When control relay SA is picked up in a manner to shortly appear to close front contacts 1 and 8, and approach control relay VD is re leased, closing back contact 9, a circuit can be traced from terminal BX of generator G over back contact 9 of relay VD, front contact 1 of relay SA, primary winding 6 of transformer TD, front contact 8 of relay SA and to terminal CX of generator G, and alternating current is supplied to primary winding 6 and is supplied in turn to the track rails of section D-E. I shall assume that the current supplied to the track rails over the circuit just traced is of a normal relative polarity. When control relay SA is released and approach relay VD is also released, the above traced circuit includes back contact I0 of relay VD and is pole changed at back contacts II and I2 of relay SA and current of reverse relative polarity is supplied to the rails of section D -E. The current thus supplied to the rails of section D-E is in each case non-coded. Assuming for the time being that a train shown conventionally at TV does not occupy section D-E, then the alternating current supplied to the rails is effective to energize a track relay E'I'R having a winding l3 connected across the rails at the entrance end E of the section. Track relay ETR is a standard two element alternating current relay and hence when its winding I3 is energized by current of normal relative polarity a contact member M of the relay is held at the left-hand position as viewed in Fig. 1, and when winding [3 is energized by current of relative reverse polarity the contact member I4 is held at the righthand position. Contact member I4 is biased to,

occupy acenter position to engage a back contact [5 whenever winding l3 is shunted and deenergized. Approach control relay VD is controlled over an obvious line circuit including back contact l5 0f relay ETR and it follows that approach. control relay VD is normally deenergized, that is, r i

when section is unoccupied. When the section D--El isoccupied so thattrack relay ETR is deenergized then approach control relay VD is energized and picked up. i 7

Relay SA- is governed by a track relay DTR for the section next in advance ofsection D-E,'- and which track relayis similar to track relay ETR of section D-E so that whenthe section next in advanceis unoccupied relay DTR is energized at either normal or reverse relative polarity closing either left-hand contact It or "right-hand con-'- tact l1 and relay SA is picked up, and when the section next in advance is occupied and track relay DTR is deenergized, then relay SA- is deenergized and released. I s

The code transmitter CTmay be any one of several well-known types and may be of the relay type having. two code contact members and I80 which are operated to engage contacts 75a and-188a, respectively, when an operating winding l8 of the code transmitter is energized,

"When section DE is, occupied causing relay- VDito be picked up and the section'next in advance is unoccupied causing relay SA to vbe picked up, alternating current of a frequency of 23 cycles per second coded at the 180 code rate is supplied to the rails of 'section DE through transformer TD, the circuit for primary winding 6 of transformer TD extending from terminal BX of generator G over front contact 2| of relay VD, contact I8'll'l80a of coder CT, front contact 1' of relay SA, primary winding 6 of transformer TD, front contact 8 of relay SA and to terminal CX of generator G. 'When the section next in advance is occupied so that relay SA is released, then alternating current from generator G coded at the '75 code rate is supplied to the track rails of section DE through transformer TD, the circuit for primary winding 6 extending from terminal BX of generator G over front contact 2| of relay VD, contact 'l5l5a of coder CT, back contact l2 of relay SA, primary winding 6 of transformer TD, back contact ll 'of relay SA and .to terminal CX. s

Train carried train control apparatus is provided for the train shown atTV and such apparatus comprises inductor 22 and 23, a standard amplifying and decoding means, and an adapter shortly to be described. The inductors electromotive forces induced therein due to cur- 7 nal TC over wire 24;

rent flowing in the rails in opposite directions at any given instant add their effects.

The amplifying and decoding means is house I, e in a standard equipment box indicated by a rectangle EB and such apparatus isof the standard form andwill be described only as required fora full understanding of my invention.

circuit terminals are provided of which terminals B32, N32, TC, T2 and FT-are shown in Fig. 1 along with a present spare terminal desig-. nated by the reference character FT I.

carried 32 volt direct current generator or battery (not shown) outside'of the equipment box,

is connected to the power supply terminals B32 and N32 for the purpose of providing power to the circuits of the train control apparatus with-t in the equipment box-EB. One terminal of in ductors 22 and 23 is cone'cted to control termi-f Theother terminal; of"

inductorsZZand 23 is in the standard form of apparatus'connected to the control terminal FT over wire 25, but according tomy invention, wire 25 is removed from terminal FT and is connected t the present sparetenninal FTl. A filter Fl is included in the apparatushoused inthe equipment box EB and is connected to terminals TC,

T2 and FT. This filterFl comprises a 'transformer Tl and two condensers 21 and 28'. Condenser 21 is connected across secondary winding 26 of transformer Tl and condenser 28is eonnected. between terminals FT and T2 and a pri-.

mary'winding 44 of transformer TI is connected between terminals TC and T2. The filter Fl is tuned to pass current of the frequency of the order of. cycles per second and I shall assume. for the apparatus of Fig, 1- that filter Fl istuned sharply to resonance at :92 cycles. per second which isthe frequency used at the present time in certain cab signal systems. .The two stage amplifier includes'tubes, ZPJ and lPJ each of which is a three element tube and the filaments Hand '30 ofwhich are connected in series across the power supply terminals B32. and N32 withresistors 3| and '32 interposed inthe connection. Thus the tubes are normally'heated and in an activecondition. Secondary winding 23and condenser 21 in multiple of filter Fl are connected across grid 33 and filament 29 of the first'stage tube lPJ- The plate circuit of tube l;PJ- receives energy from the usual 300 volt dynamotor, (notshown) but whose terminals'arej indicated at B300 and N300 and thisplate' cir-' cuit is coupled to the grid circuitof the second 7 stage tube ZPJ, through an 'interstage transformer T3. The plate circuit of the second stage tuheZPJ includes the 300 'voltcurrent source and a primary winding 34 of an output transformer T4 to whose secondary winding 35 a master code following relay MB is connected. The arrangement is such thatwhen coded alternating current of 92.cy'cles.per second is applied across. terminalsTC and FT. it is passed by filament Fl and amplified'a't tubes lPJand ZPJ and relay MB. is operated at a rate corresponding to, the

code rate of thealternating current. Relay MR when operated controls at its contact'member 36 At a proper location'within the equipment box EB,

A train is applied to two decoding circuits one of which includes a reactor 39 and the other of which includes a condenser 40 and a reactor 4| in series. At least a portion of reactor 39 is connected to a relay LR through a rectifier 42 and at least a portion of reactor 4! is connected to a relay AR through a rectifier 43. The circuit including reactor 39 is non-tuned and hence relay LR is effectively energized and picked up when relay MR is operated at a rate corresponding to either the 75 or 180 code rate. The circuit including condenser 40 and reactor 4| is tuned to resonance at the frequentcy of the electromotive force induced in secondary winding 38 of transformer T when relay MR is operated at a rate corresponding to the 180 code rate and hence relay AR is effectively energized and picked up for the 180 code rate but not for the 75 code rate. Relays AR and LR are used to control suitable train control devices, such as a cab signal CS. The operating circuits of cab signal CS are selectively governed over contacts of relays AR and LR in the usual manner and which will be apparent from an inspection of Fig. l.

The adapter is mounted in a box indicated by a rectangle AB and comprises a manually operable switch SW, a frequency changer and an amplifier. The switch SW is a four pole double throw switch, a first or top center pole of which is connected to terminal FTI of equipment box EB over wire 41, a second and a third center pole are connected to terminals B32 and N32 of box EB over wires 45 and 46, respectively, and its fourth center pole is connected to terminal FT over wire 48, wire 48 being also connected to the first left-hand pole of the switch. The other left-hand poles of the switch are idle and the four right-hand poles are connected to circuits of the adapter as will shortly appear.

In Fig. 1, the frequency changer comprises two frequency doublers. Such frequency doublers may take any one of several forms and may be of the type consisting of a full wave rectifier and a transformer. Looking at Fig. 1, a full wave rectifier 49 has one input terminal connected to terminal TC of the equipment box EB over wire 50 and its other input terminal connected to the first or top right-hand pole of switch SW through a condenser 5|. The output terminals of rectifier 49 are connected to primary winding 52 of a transformer T6 across whose secondary winding 53, a condenser 54 is connected. The condenser 5| is proportioned to tune inductors 23 and 22 when connected thereto to resonance at 23 cycles per second and secondary winding 53 is parallel tuned by condenser 54 to resonance at 46 cycles per second. It follows that when switch SW is thrown to its right- hand position inductors 22 and 23 are connected across the input ter-- minals of rectifier 49 through condenser 5| and the 23 cycle electromotive force picked up by the inductors due to the coded rail current causes a 46 cycle electromotive force to appear across secondary winding 53 and condenser 54 due to the rectifying action of rectifier 49. Secondary Winding 53 of transformer T6 is connected across the input terminals of a full wave rectifier 55 whose output terminals are connected to primary winding 55 of a transformer T1. A secondary winding 51 of transformer T1 is parallel tuned to resonance at 92 cycles per second by a condenser 58 and consequently when an electromotive force of 46 cycles per second is made to appear across the secondary winding 53 of transformer T6 it is rectified and an alternating electromotive force of 92 cycles per second is caused to appear across secondary winding 58 of transformer T1 due to the rectifying action of rectifier 55. Thi 92 cycle electromotive force appearing across secondary winding 51 is applied to the grid circuit of an amplifier electron tube 59, electron tube 59 being here shown as of the indirect heater type.

When switch SW is thrown to the right the power supply terminals B32 and N32 of equipment box EB are connected to a filament circuit and a plate circuit of tube 59. The filament circuit can be traced from terminal B32 over wire 45, second right-hand pole of switch SW, wire 60, filament 6| of tube 59, a resistor 62, wire 63, third right-hand pole of switch SW and wire 46 to terminal N32. The plate circuit for tube 59 branches from wire 60 of the previously traced filament circuit through primary winding 64 of a transformer T8, plate 65 and intervening tube space to cathode 66 of tube 59, and thence to wire 63 of the filament circuit. The primary winding 64 of transformer T8 is parallel tuned by a condenser 61 so that the 92 cycle electromotive force created across secondary winding 51 of transformer T1 is amplified at tube 59 and creates a corresponding electromotive force in secondary Winding 68 of transformer T8, which secondary winding 68 serves as an output Winding of the adapter. Output winding 68 is connected to the control terminals TC and FT of the standard equipment box EB through switch SW in the right-hand position. Starting at terminal FT this connection includes wire 48, fourth righthand pole of switch SW, an impedance 10, wire 69, secondary winding 68, and wires H and 50 to the control terminal TC. Thus the 92 cycle electromotive force created in output winding 68 is applied to the standard amplifying and decoding means for operation thereof.

It is to be seen therefore that when switch SW is thrown to the left the adapter is inactive and the inductors 22 and 23 are connected directly to the control terminals TC and F1 of the standard equipment box for operation of the train control apparatus by the electromotive forces picked up by inductors 22 and 23 as would be the case when the apparatus is used with 92 cycle alternating current track circuits. When switch SW is thrown to the right, the adapter is energized and the inductors 22 and 23 are connected to the input side of the adapter whose output side (secondary winding 68) is connected to the terminals TC and PI of the standard equipment box and the 23 cycle electromotive force picked up by the inductors 22 and 23 when the train occupies track section D--E is converted to coded alternating current of 92 cycles and this latter current is applied to the usual terminals TC and FT of the standard equipment box for operation of the standard amplifying and dccoding means.

It is to be observed that while in Fig. 1 the two frequency doublers of the adapter are arranged in cascade and the amplifier is placed in the output of the second frequency doubler, this order of these devices is immaterial and the amplifier can be placed ahead of the first frequency doubler or it may be interposed between such frequency doublers. It is also to be observed that if further increase in the frequency is required an additional frequency doubler can be included in the adapter.

In Fig. 2, the trackway portion of the apparatus, the train carried inductors and the standard amplifying and decoding means are the same as in Fig. 1 and further description of this apparatus is not required. Also the manual operable switch SW placed in the adapter box AB is the same as in Fig. 1 and has its poles connected to terminals E32, N32, FI and FTI of box EB in the same manner as in Fig. 1.

In Fig. 2 an-adapter including a magnetic bridge type amplifier and a generator is provided. When the switch SW of Fig. 2 is thrown to the right the inductors 22 and 23 are switched to a tuned inductor L2 througha condenser 12 which is proportioned to tune the inductors 2'2 and 23 and their connection to inductor L2 to resonance at the frequency of the track circuit current, that is, it is tuned to resonance at a frequency of the order of cycles persecon'd. A condenser 13 is connected across inductor L2 to tune the inductor to resonance at the frequency of the track circuit current. At least a portion of inductor L2 is connected to the input terminals of a full .wave rectifier l4 and'the unbalance'the bridge with, the result that 100 cycle alternating current is supplied to theload winding 84.

' Consequently when coded alternating current of the frequency of the order of 20 cycles per second is picked up by inductors 22 and ,23 due to the train occupyingsection D-E, such curplied to the output winding 84, the coding of the 100 cycle alternating current being the same as the coding of the alternating current picked up from the track rails. The generator GI as shown in Fig. 2 is driven by a small motor 85 which is connected to the power supply terminals B32 and N32 of the equipment box EB when switch SW is thrown to the right. This circuit for motor 85 includes the second and third right-hand poles of switch SW as will be apparent from an inspection of Fig. 2. It is to be noted that instead of a motor generator consisting of a motor output terminals of this rectifier are connected to an input winding consisting of coils 18a. and 18b of a magnetic bridge type amplifier having two magnetic core structures A and B. Each core structure A and B is of a three-legged form and besides the input'winding coils 78a and 13?) mounted on the central leg of the cores A and B, respectively; two .bridge arm windings consisting of'two coils l1 and 18 mounted on the left-hand leg and right-hand leg of cores A and B, respectively, and two bridge arm windings consisting of two coils l3 and 80 mounted on the right-hand leg of core A and the left-hand leg of core B, respectively, are provided. A biasing winding consisting of two coils 8| and 82 is mounted on the center legs of the cores A and B and a source of direct current, such asa battery 83 is interposed in the circuit of the biasing winding to provide a predetermined initial direct current fiux in the cores.

Alternatng current of a frequency of the order of 100 cycles per second is supplied to the bridge windings H, 18, T9 and 80 from a small generator G1, the arrangement being such that windings ll, 18, i9 and 88 are connected to form the well-known Wheatstone bridge arrangement. This structure of the magnetic amplifier is that covered by Letters Patent of the United States No. 1,824,577, granted September 22, 1931, to A. J. Sorensen for Electrical translating apparatus, and it is suflicient for the instant application to point out that input coils 18a and 16b are so connected that'the flux created by current supplied from rectifier 14 aids the biasing flux created in core A by the current flowing in biasing winding 8| but opposes the biasing flux created in core B by current flowing inbiasing winding 82. When no current'flows'in the input winding Ito-16b the bridge windings are balanced so that no currentis supplied to a load winding 84 connected'across the opposite corners of the Wheatstone bridge. When unidirectional current is supplied to the input winding map-13b theimpedance of core A is varied in one direction due to the unidirectional flux created by the current flowing in coil 16a aiding the flux created by biasing winding 8|, and the impedance of core B isvaried to the opposite direction due to the unidirectional flux created by current flowing in input coil 16b opposing the biasing flux created by winding 82, and such variations of the impedances of cores A and B and generator GI a vibration type of alternator may be used the operating winding of which would be connected to the power supply terminals in the same manner that 'motor 85 is connected thereto. It should also be noted that the' I biasing winding 8l-82 which is supplied with current from battery: 83 maybe supplied with direct current from the power supply terminals B32 and N32 ifdesired.

. The load winding 84 serves as a'prirnary winding for a I transformer T9, whose secondary winding 86 serves as an output winding for the adapter and is connected to the control terminals TC and FT of the standard equipment box EB over wires 48 and. 58 and the fourth righthand pole of switch SW. It is to beseen there- Y fore that whenswitch SW, of Fig 2is thrown to the left the inductors 22 and 23 are connected to the control terminals TC and F1 the same as in present day practice and when switch SW is thrown to the right the adapter is energized and made active and is interposed in the con-' nection between inductors 22 and 23 and terminals TC and FT of the standard equipment box.

v With the apparatus of Fig. 2 the frequency of the current supplied by the adapter for operation of the standard train control apparatus housed in equipment boX EB is not directly dependent upon the frequency of the track rail current. Thus the current supplied by .the track rail apparatus of Fig. 2 may be any preselected frequency of the order of 20 cycles per second as will provide effective-broken rail protection. The generator included in the adapter is set to deliver a current of the'frequency at which the standard apparatus is tuned and in the instant case it is set to deliver current of a frequency of the order of cycles per second.

Referring to Fig.- 3, the trackway portion of the apparatus and the train carried amplifying and decoding means are the same as in Fig. 1.

Also switch SW mounted in box AB is connected by an inspection of Fig. 3. A condenser 89 is interposed in this circuit connecting the induc tors to winding 88 and is proportioned to tune the circuit to resonance at the frequency of the alternating current supplied to the track circuit of section DE of Fig. 3. That is, this circuit including the inductors is tuned to resonance at a frequency of the order of 20 cycles per second or some preselected frequency that is effective to provide satisfactory broken rail protection. A condenser 90 is connected across a secondary winding SI of transformer TH) to parallel tune secondary winding 9| to resonance at the frequency of the track circuit current. At least a portion of secondary winding 91 of transformer TH] is connected to the input terminals of rectifier 87 whose output terminals are connected across resistor R2. It follows that the electromotive force picked up by inductors 22 and 23 is rectified and a unidirectional current is supplied to resistor R2 causing a voltage drop across that resistor during each on period of the coded track circuit current. Hence the voltage created across resistor R2 has on and off periods substantially in step with the on and off periods of the track circuit current. Resistor R2 is preferably bypassed by a condenser 92 for reasons to shortly appear.

Oscillator tube OS may be of the indirect heater type, the filament 93 of which is connected to the power supply terminals B32 and N32 of equipment box EB when switch SW is thrown to the right over an obvious circuit including a current limiting resistor 94. The reactive transformer Tll has three windings. A first winding 95 of transformer TM is included in the plate circuit of tube OS by one terminal of winding 95 being connected to the power supply terminal B32 over the second right-hand pole of switch SW, the other terminal of winding 95 being connected to the plate 96 of tube OS, and the cathode 91 of tube OS being connected to the power supply terminal N32 over the third right-hand pole of switch SW. A second winding 98 of transformer TH is parallel tuned by a condenser 99 and the two in multiple are connected between control grid H39 and cathode Q! of tube OS, a blocking condenser H3! being interposed in the connection to control grid H30. Winding 95 included in the plate circuit supplies through secondary winding 98 the necessary feed back for oscillation and the tuning of winding 88 sets the frequency of the oscillations. Winding 98 and condenser 99 are proportioned to provide oscillations of a frequency of the order of 100 cycles per second. That is, the winding 98 and condenser 99 are proportioned to cause oscillations of a frequency corresponding to the frequency at which the associated standard train control apparatus is tuned. Resistor R2 is connected-across control grid I and cathode 91 through a battery H32, and condenser 92 serves to by-pass resistor R2 to prevent the fundamental frequency of the energy picked up by the inductors 22 and 23 and its multiple frequencies so that such frequencies do not appear in the output of tube OS.

When no voltage is developed across resistor R2 the voltage of biasing battery H32 provides a negative grid bias voltage sufficient to cause substantially no plate circuit current and hence no oscillations are generated. The connection of resistor R2 is such that the voltage developed across resistor R2 during an on period of the coded energy picked up by inductors 22 and 23 drives grid I00 more positive in potential with respect to cathode 97 so that plate circuit current flows and tube OS is set into oscillation. Hence the on and off periods of the oscillations developed by tube OS are substantially in step with the on and off periods of the coding energy picked up by inductors 22 and 23 and indirectly in step with the on and oif periods of the coded track circuit current.

A third or output winding I63 of transformer TH is connected across control terminals TC and FT of equipment box EB over the fourth right-hand pole of switch SW and hence when tube OS is caused to oscillate an electromotive force of a frequency corresponding to the frequency of the oscillations is induced in winding I83 and applied to control terminals TC and FT to cause operation of the standard amplifying and decoding apparatus.

It is to be seen therefore that when switch SW of Fig. 3 is thrown to the left, inductors 22 and 23 are connected directly to terminals TC and FT of the equipment box the same as in Figs. 1 and 2 and conditions the apparatus of Fig. 3 for operation over present day track circuits, and when switch SW is thrown to the right the adapter is energized and interposed in the connection between inductors 22 and 23 and the terminals TC and FT of the equipment box EB with the result that the coded energy of a relatively low frequency picked up by inductors 22 and 23 is converted into coded alternating current of a relatively high frequency suitable for operation of the standard amplifying and decoding means.

It should be noted in connection with Fig. 3 that biasing battery I02 may be omitted and grid I00 provided with no normal negative grid bias voltage so that when no voltage is developed across resistor R2 tube OS is caused to oscillate and produce a corresponding electromotive force in the output Winding I03 of transformer TH and which output electromotive force is applied to terminals TC and FT. Under such conditions resistor R2 is so connected that the voltage developed across the resistor during an on period of the energy picked up by inductors 22 and 23 drives grid I00 more negative in potential with respect to the cathode and the oscillations cease. With the apparatus of Fig. 3 thus arranged an inverse code would be applied to the standard amplifying and decoding means. Since the on and off periods of the coded track circuit current are substantially equal an electromotive force of an inverse code when applied to the standard amplifying and decoding means provides satisfactory operation thereof.

It is apparent that in each of the three different forms of apparatus embodying my invention, I have provided train carried train control apparatus incorporating an inexpensive adapter capable of being located in a separate box outside of the standard equipment box and which adapter is effective to make the standard amplifying and decodingmeans operable on coded alternating current of a relatively low frequency notwithstanding such amplifying and decoding means is designed and tuned for operation by coded alternating current of a relatively high frequency. Also the change-over of the train carried apparatus from a condition of response to coded alternating current of a relatively high frequency to response to coded alternating current of a relatively low frequency is accomplished by throwing a manually operable switch.

Although I have herein shown and described only three forms of railway traffic controlling apparatusembo'dying 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 my invention. 7 I v Having thus described my invention what I claim is:

1. In railway traflic controlling apparatus for use with train carred amplifying and decoding means responsive to coded alternating current of a preselected relatively high frequency and which current is received through inductors mounted on the train in inductive relation to the track rails, the combination comprising, means to supply to the rails of a track'sectioncoded alternating current of a preselected relatively low a rent coded at either said first-or said second code rate into 100-(cycle alternating current coded at 1 the corresponding code rate, and switching means effective at a preselected positionlto interpose said converting means in the connection of said inductors to said amplifying and'decoding means. I v v v 1 5. In railway trafiic controllinglapparatus for usewithtrain carried amplifying and-decoding means tuned sharply to resonance at a frequency of the order of 100- cycles per second and adaptable of responseto such current coded at. either a'firstor a second code rate, the combination in inductive relation to the track rails, the combination comprising, means to supply to the rails of a track section alternating current of a preselected relatively low frequency coded at said different preselected code rates according to traffic conditions in advance of said section, and a frequency converting means interposed in the connection between said inductors and said amplify-,

ing and decoding means to convert said low frequency alternating current coded at any particular one of said code rates into alternating currentof said preselected high frequency coded at a corresponding code rate.

3. In railway tramc controlling apparatus for use with train carried amplifying and decoding means responsive to coded alternating current of a preselected relatively high frequency and which current is received through inductors mounted on the train in inductive relation to the track rails, the combination comprising, means to supply to the rails'of a track section coded alternating current of a preselected relatively low frequency, a frequency converting means adaptable of converting said low frequency alternating current coded at a particular code rate into alternating current of said preselected high frequency coded at said particular code rate, and switching means effective at one position to interpose said frequency converting means in the connection of said inductors to said'amplifying;

and decoding means and effective at another position to connect saidinductors directly to the amplifying and decoding means.

4. In railway traffic-controlling apparatus for use with train carried amplifying and decoding means responsive to alternating current of a frequency of the order of 100 cycles per second coded at either a first or asecond code rate and.

which current is received through inductors mounted on the train in inductive relation to the track rails, the combination comprising, means to supply to the rails era section alternating current of the frequency of the order of '20 cycles per second coded at either said first or said second code rate according to traffic conditions in advance of said section, converting meansadaptable of converting said 20 cyclealternating curcomprising, means to supply to the-rails 'off-a track-section alternating current of a frequency of the order'of 20' cycles per second coded at either said first or said second code rate 'according to a first or a second traffic condition in advance of said section, an inductor mounted'on the train inlinductive relation tothe track "rails to inductively receive .when the trainoccupies said section a current of the'frequency and code rate of that supplied to the rails'of the section, a train carried adapter including a two-way switch and frequency converting means operativeto convert alternating current of the frequency of the order of 20 cycles per second coded at either said first or said second coderate into alternating current of 'the frequency of theorder of 100 cycles per second coded at a corresponding code rate',and said switch effective at-a selected one of its positions to interpose said adapter between said inductor and said 'amplifyingiand decoding means. 5 I 1 6. Inl railway trafiic controlling apparatus for use with train carried amplifying and decording means responsive to coded alternating current of 100 cycles per-b second inductively received throughan inductor mountedon the train in in.-'

ductive relation to-thetrack rails, the combination comprising, means to supply to the track rails of a tracksection coded alternating current of 20cyc1es per second,a train carried frequency converteriadaptable of converting current of 20 cycles to current of 100 cycles per second, and a manually operable double throw'switch'. interposed in the connections of said inductor to the input terminals of said amplifying .and decoding means to: connectsaidinductor directly to said terminals in a-selectedone of the-positions of the switch and 'to connect said inductor to said terminals. through said frequencyconverter in the .other'position ofthe switch. 1

7.. In railway traffic controlling apparatus for use with train carried traincontrol equipment including an electrontube amplifier and a filter with the filterconnected between the input terminals of such equipmentand said amplifier, and which filter comprises inductances and capaci tance tunedsharply toresonance at a preselected first frequency, the combination comprising, a track section, means to supply to the rails of the section alternating current of a preselected second frequency'which is different from said first frequency, train carried inductors mounted on the train in inductive relation to the rails to receive an alternating current of said secondfre-v quencywhen the train occupies the section, a train carried adapter including frequency converting means effective to convert alternating current of said second frequency into alternating current of said first frequency, and switching means effective atone position to connect said inductors directly to the input terminals of said I train controlvequipment and effective at another position to connect said inductors to the input side of said adapter and the output side of the adapter to the input terminals of the train control equipment.

8. In combination with standard train carried train control apparatus including a filter tuned sharply to resonance at a preselected relatively high frequency and connected to designated terminals of an equipment box housing such train control apparatus, inductors mounted on the train in inductive relation to the track rails, trackway means to supply to the track rails of a track section alternating current of a preselected relatively low frequency as required to provide satisfactory broken rail protection for the section and to induce in said inductors an alternating current of said low frequency when the train occupies said section, a train carried frequency changer responsive to alternating current of said low frequency to create alternating current of said high frequency, a double throw manually operable switch, circuit means including a first position of said switch to connect said inductors to said designated terminals of the equipment box, and circuit means including a second position of said switch to connect said inductors to the input side of said frequency changer and the output side of the frequency changer to said designated terminals.

9. In combination with standard train carried train control apparatus including a filter tuned sharply to resonance at a frequency of the order of 100 cycles per second and connected to designated control terminals of an equipment box housing such train control apparatus and which box is provided with designated power supply terminals, trackway means to supply to the rails of a track section alternating current of a frequency of the order of 20 cycles per second to provide effective broken rail protection for that section, inductors mounted on the train to receive an electromotive force of a frequency the same as that of the rail current when the train occupies said section, a train carried adapter including a frequency changer and an amplifier made responsive to an electromotive force of a frequency of the order of 20 cycles per second when supplied by direct current to create an alternating current of a frequency of the order of 100 cycles per second, a double throw manually operable switch, and circuit means including a selected position of the switch to connect said power supply terminals and said inductors to said frequency changer and amplifier and to connect an output circuit of the amplifier to said control terminals.

10. In combination with train carried train control apparatus including a filter tuned sharply to resonance at 92 cycles per second and connected to designated control terminals of an equipment box housing such train control apparatus and which box is provided with designated power supply terminals, trackway means to supply to the rails of a track section 23 cycle alternating current to provide effective broken rail protection for that section, inductors mounted on the train to receive a 23 cycle electromotive force when the train occupies said section, a train carried adapter including a first and a second frequency doubler and an electron tube amplifier, said frequency doublers connected in cascade to convert a 23 cycle electromotive force into a 92 cycle electromotive force, said electron tube amplifier having its grid circuit connected to said second frequency doubler to amplify in its plate said'plate circuit to receive energy due to such amplified 92 cycle electromotive force; and switching means effective 'at a preselected position to connect said inductors to said first frequency doubler, to connect said power supply terminals to said amplifier tube and to connect said winding to said control terminals to operate said train control apparatus in response to the energy received by said inductors.

11. In combination with train carried train control apparatus including a filter tuned sharply to resonance at 92 cycles per second and connected to designated control terminals of an equipment box housing such train control apparatus and which box is provided with designated power supply terminals, trackway means to supply to the rails of a track section 23 cycle alternating current to provide effective broken rail protection for that section, inductors mounted on the train to receive a 23 cycle electromotive force when the train occupies said section; a train carried adapter including a first and a second frequency doubler, an electron tube amplifier and an output winding; a manually operable switch, a first circuit means including a preselected position of said switch to connect said inductors and said power supply terminals to said adapter to convert the 23 cycle electromotive force received by the inductors into a 92 cycle electromotive force which is amplified and supplied to said output winding, and a second circuit means including said preselected position of the switch to connect said output winding to said control terminals to operate said train control apparatus by the electromotive force thus supplied to the output winding.

12. In combination with train carried train control apparatus tuned sharply to resonance at a preselected relatively high frequency and connected to designated control terminals of an equipment box housing such train control apparatus, trackway means to supply to the rails of a track section alternating current of a preselected relatively low ferquency as required to provide effective broken rail protection, inductors mounted on the train to inductively pick up energy in response to such low frequency alternative current when the train occupies said section, a train carried adapter including a generator and a bridge type magnetic amplifier having a control input circuit and a bridge circuit and a load winding, said generator effective to supply alternating current of said high frequency to said bridge circuit, a manually operable switch, a rectifier, circuit means including a preselected position of said switch to connect said inductors to said control circuit through said rectifier to cause current to be supplied from the generator to said load winding in response to the energy picked up by said inductors, and another circuit means including said preselected position of the switch to couple said load winding to said control terminals to operate the train control apparatus by such current supplied to the load winding.

13. In combination with train carried train control apparatus tuned sharply to resonance at a preselected relatively high frequency and connected to designated control terminals of an equipment box housing such train control apparatus, trackway means to supply to the rails of a track section alternating current of a preselected relatively low frequency coded at a given code rate, inductors mounted on the train in inductive relation to the rails to pick up energy in response to such coded low frequency alternating current when the train occupies said section, a

train carried adapter'including a rectifier and an electron tube-oscillator operative to create oscillations of said relatively high frequency, circuit means to connect said inductors to the control grid of said tube through said rectifier tovary the, potential of said grid with respect to the cathode of the tube in step with the code rate of the low frequency energy picked up by the inductors and cause said tube to assume oscillating and non-oscillating conditions in step with said code rate, and circuit means to couple the plate circuit of said tube to said control terminals to cause operation of saidtrain control apparatus by the oscillations created by said tube.

14. In combination with train carried train control apparatus tuned sharply to resonance at a preselcted relatively high frequency and connected to designated control terminals of an equipment box housing such train control apparatus, trackway means to supply to the rails of a track section alternating current of a'preselected relatively 'low frequency coded at a given code rate, inductors mounted on the train in inductive relation to the rails to pick up energy in response to such coded low frequency alternating 7 current when the, train occupies said section, a

train carried adapter including a rectifier, a resistor, an electron tube oscillator and an output winding said resistor interposed-in the grid circuit of said tube and said output winding coupled to the plate circuit of said tube, said tube operative to createoscillationof said relatively high frequency but normally biased to a non-,oscillat ing condition, circuit means including a given position of said switch to connect said inductors across; said resistor through said rectifier to create a voltage drop-across the resistor in step with the code of the energy picked up by said I PAUL N. BOSSART.

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