US2243722A - Railway traffic controlling apparatus - Google Patents

Description

y 1941 c. E. STAPLES 2,243,722

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed June 22, 1958 4 Sheets-Sheet l Sibae VA VA Mwa'QVA VA VA wwdeV/A VM/Alj A 24 LOLA)? BQ Amglz'fiep I A INVENTOR (Tau/f0 ESzaplem 57 BY 2 58 1 H16 ATTORNEY y 1- c. E. STAPLES 2,243,722

RAILWAY TRAFFIC CONTROLLING APPARATUS 'Filed June 22, 1958 4 Sheets-Sheet 2 M I Hi'g'hwag /Ma vHIS ATTORNEY c. E. STAPLES 2,243,722

RAILWAY TRAFFIC CONTROLLING APPARATUS 4 Sheets-Sheet 3 May 27, 1941.

Filed June 22, 1938 cm QM) H [S ATTORNEY May 27, 1941. c. E. STAPLES RAILWAY TRAFFIC CONTROLLING APPARATUS Filed June 22, 1938 4 Sheets-Sheet 4 7 H15 ATTORNEY Patented May 27, 1941 UNlTE STATES r QFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Application June 22, 1938, ,Serial No. 215,203

30 Claims.

My invention relates to railway trafli'c controlling apparatus and it has special reference to the organization of such apparatus into systems wherein either or both wayside signals and train carried cab signals are controlled by coded energy having cycle patterns of the time code type.

One object of my invention is to provide a new and improved form of such organization.

Another object is to lower the cost and simplify the construction of trafilc governing systems which operate on the time code principle.

An additional object is to lower the power consumption, and improve the operating characteristics of the decoding apparatus which is utilized by systems of the class named.

A further object is to accomplish the above without dispensing with any of the desirable features of continuously coded track circuit control.

In practicing my invention I attain the above and other objects and advantages by providing new and improved facilities for selectively responding to differences in the relative lengths of the on and the ofi periods of the cycles of coded energy by which the signalling system is controlled. These facilities make use of a pair of delayed response decoding relays which are respectively energized by the positive and by the negative half cycles only of the output voltage of the usual decoding transformer. That transformer, in turn, receives primary current pole changed in customary manner by a code following relay which is operated by the pulses of the time code energy referred to above. Each decoding relay is designed to respond only when the effective intensity of its energizati'on rises above a given critical value and, in consequence, codes having long on and short ofi periods pick up only one of these relays, codes having short on and long ofi periods pick up the other relay only, and codes having substantially equal on and 01f periods pick up both of the relays.

I shall describe a few forms of railway traffic controlling apparatus embodying my invention and shall then point out the novel features thereof in claims. These illustrative embodiments are disclosed in the accompanying drawings in which:

Fig. l is a diagrammatic representation of a stretch of railway track equipped with trafiic controlling apparatus embodying my invention;

Fig. 2 is a diagrammatic representation of four different forms of coded trackway energy which may be used to control my new signalling system;

Fig. 3 is a view of a portion of the apparatus of Fig. 1 provided with relay energizing circuits of a modified form;

Figs. 3a and 3b are similar views showing two separate decoding transformers connected to replace the single decoding transformer which respectively is used by the two signal location equipments of Fig. 1;

Fig. 4' is a diagrammatic view of train carried apparatus suitable for cooperation with and control by the trackway equipment of Fig. 1;

Fig. 5 is a representation of the improvements of my invention applied to a signalling system which is controlled by energy coded differently than in Fig. 1;

Fig. 6 represents an application of my new apparatus to a track section which at times receives a third or detection code;

Fig. 7 represents an application wherein the number of wayside signal indications is extended to four;

Fig. 8 is a similar showing of an application wherein the number of signal indications is extended to five;

Fig. 9 is a showing of an alternate form of energizing circuit for one of the decoding relays of Fig. 8;

Fig. 10 represents the signal control circuits of Fig. 8 arranged in a somewhat different manner;

Fig. 11 shows the improvements of my invention applied to a six indication system of automatic block signalling;

Fig. 12 shows my inventive improvements incorporated in a five indication system involving line wire control; and

Fig. 13 rep-resents modified energizing circuits for the decoding transformer and the decoding relays of Fig. 12.

In the several views of the drawings like reference characters designate corresponding parts. Referring first to Fig. 1, the improvements of my invention are there disclosed as being incorporated in the trackway portions of a combined automatic block signalling and cab signalling system for a track |-2 over which it will be assumed that traffic moves in the single direction indicated by the arrow, or from left to right in the diagram. Insulated rail joints 3 divide the protected stretch of this track into the customary sections is a wayside signal S which is adapted to indicate to an approaching train the nature of the trafiic conditions in the blocks immediately ahead. As shown, these signals are of a wellknown color light type and each consists of three lamps G, Y and R which, when energized, respectively direct rays of green, yellow and red light into the range of vision of the engineman of an approaching train.

The track circuit of which the rails of each of the referred to sections of track form a part is supplied with coded train control energy having cycle patterns of the time-code type. In form, this energy may be either alternating current as indicated in Figs. 1, 6, 8 and 11, or direct current as indicated in Fig. 5. If desired, moreover, energy of both characters may be used as indicated in Fig. 7.

In all of the applications herein represented, the energy referred to above is supplied to the rails at the traffic leaving or exit end of the section by means of a circuit which includes the usual current limiting impedance '4. As shown in Fig. -1, this circuit also includes the customary track transformer TT which at proper times is connected with a pair of power supply terminals B and .C. To aid explanation it will be assumed that these terminals are identified with an alternating current source the energy of which has a frequency of 60 or 100 cycles per second.

The particular signalling system shown in Fig. 1 is of the three indication variety and it makes use of track circuit energy of two different codes. These are represented in the upper portion of Fig. 2 where they are respectively identified by the characters S-L and LL, and both areproduced by acoding device CT which serves to interrupt the rail supply circuit in the periodic or recurring manner which is necessary to produce them.

From Fig. 2 it will be seen that the S-'L code is made up of recurring cycles, each of which consists of a short on period and a substantially longer off period. Similarly, the L-L code will be seen to consist of recurring cycles each of which is made up of .a long on period followed by an off period of substantially the same length. Although the long off periods of the two codes are shown as being of similar lengths, it will be apparent, as the description proceeds, that this relation is not necessarily essential.

As illustratively shown at CT in Fig. 1, each of the mentioned code transmitters is of a wellknown motor driven type and is provided with two separate contacts SL and LL which respectively produce the two correspondingly identified codes of Fig. 2. By means of aselector contact B of a relay BQ, later to be described, one or the other of these contacts is included in the primary circuit through which the track transformer 'TT is energized from the alternating current source BC.

In the case of contact LL, the actuating mechanism is so arranged that the recurring periods of circuit completion and circuit interruption are substantially equal and relatively long, while in the case of contact S-L the mechanism operates to'produce relatively short periods of circuit completion separated by longer periods of circuit interruption Specially shaped cams constitute one convenient means for obtaining these distinctive code cycle operations.

If desired, of course, device CT may also be of the direct current oscillating type wherein each of the coding contacts is operated by a cam driven by a ratchet which is attached to the shaft of the oscillating mechanism, the cam being so shaped as to give the desired code. In the case of equal on and oif period codes, further simplification may be obtained by employing contacts which are directly operated by the oscillating mechanism.

Each of the referred to track circuits further includes the operating winding of a track relay TR which is installed at the traffic entering end of the track section and which receives operating energy from the rails thereof. Each of these track relays is of the single element code following type and the winding thereof may be designed to respond either to alternating current as shown in Figs. 1, 6, 8 and 11, or to direct current as shown in Figs. 5 and '7.

As long as the relay winding is deenergized, the relay contacts are released and occupy the lowermost position, shown dotted in the diagrams. When, however, the track rails transmit coded energy to the relay, its response to the individual pulses thereof causes these contacts to pick up and occupy the uppermost position, shown heavy in the diagram, upon the occasion and for the continuance of each of these pulses.

In the illustrative automatic block signalling system of Fig. 1, energy of one or the other of the previously described SL and LL codings is normally fed to the track circuit at all times and this coded energy is used to control both the wayside signals S and cab signals mounted on the train which proceeds along the track l--2. One form of the latter is represented at CS in Fig. 4 and will be described more fully in a later portion of the specification.

For effecting the control mentioned in the preceding paragraph, I employ improved decoding apparatus which responds in a new and novel manner to differences in the relative lengths of the on and the off periods of the controlling code cycles. This apparatus is governed by the code following relay TR and makes use of a decoding transformer DT, which receives primary current under the usual control of a pole changing contact I of the track relay, and a pair of delayed response decoding relays FQ and BQ which are connected in a special manner with the secondary winding of transformer DT to receive operating energy therefrom.

, These energizing circuits for the relays FQ and BQ both incorporate rectifying means arranged in such manner that what will be termed the positive half cycles only of transformer secondary voltage are effective to pass current through the winding of relay FQ and what will be termed the negative half cycles of secondary voltage only are effective to pass current through the winding of relay BQ.

As shown at location E in Fig. 1, the referred to rectification is accomplished by means of static rectifiers 8 and lil of the copper oxide or other equivalent type. Each is serially connected with the winding of the associated relay in a circuit which includes a portion of the secondary Winding of the decoding transformer DT. As shown in Fig. 1, this winding is provided with a mid tap connection H which is included in both of the relay energizing circuits. In cases where it may be desired to separate the two circuits, the modified arrangement shown in Fig. 3 may be employed. There the decoding transformer DT2 is provided with two separate secondary windings l2 and I3 which respectively supply the relays F61 and BQ.

Under the control of contact 1 of the code following relay TR, the primary Winding of the decoding transformer DT receives pole changed energizing current from any suitable direct current source designated by the terminals plus and minus. These terminals may be identified with a battery (not shown) or with the output circuit of a rectifier (again not shown) which receives 100 cycle or other signal frequency energy from the alternating current source BC.

Each time that the pole changing contact 1 of relay TR is picked up, direct current fiows in the direction of right to left, as indicated by the small full line arrow, through one portion of the transformer primary and by way of a circuit shown as extending from the positive supply terminal through front contact I, conductor l5, the right half of the transformer winding and mid tap I6 back to the negative supply terminal. Likewise, each time that the contact I is released, current flows in the opposite direction, as indicated by the small broken line arrow, or from left to right through another portion of the winding and by way of a circuit shown as extending from the positive supply terminal through back contact 1 of device TR, conductor H, the left half of the transformer winding and mid tap l6 back to the negative supply terminal.

In thus pole changing the direct current primary circuit for the decoding transformer DT, contact I causes the transformer to induce in its secondary winding an alternating current voltage the frequency of which is the same in cycles per minute as the code pulse rate of the trackway energy to which relay TR is responding. If the on and the off periods of this code are of equal length, as in the case of the L-L code shown in Fig. 2, the energy contents of the positive and the negative half cycles of this secondary voltage will be equal and relays FQ and BQ will then both receive rectified energizing current of the same magnitude.

If, however, the on periods of the code are short as compared to the off periods, as in the case of the SL code of Fig. 2, then the energy content of the positive half cycles of secondary voltage will be reduced while that of the negative half cycles will be proportionately increased and in such a situation the magnitude of the energizing current received by relay BQ will be much greater than that received by relay FQ. Finally, if the on periods of the code are long as compared with the off periods, as in the case of code Lr-S of Fig. 2, the energy content of the positive half cycles of secondary voltage will be increased and that of the negative half cycles will be diminished and relay FQ will then receive rectified energizing current in increased magnitude while the energization of relay BQ will be correspondingly decreased.

These decoding relays FQ and BQ are of the direct current type and are so designed that both their pick-up and their release characteristics are delayed. Conveniently, the necessary slowness of response may be obtained by providing the magnetic circuit of therelay with a copper ferrule or other element which acts to oppose suddent changes in the intensity of flux which the relay winding circulates through the circuit. Moreover, the winding of each of these relays is so coordinated with its just described energizing circuit and withthe contact actuating elements of the relay that when the decoding transformer DT is pole changed in accordance with the pulses of an equal on and off code which is received by relay TR, the contacts of the decoding relay will be picked up and there held continuously; when the energy content of the active half cycles of secondary Voltage is higher than in the case of the equal on and off period code response, the response just described will again be effected by the decoding relay; but that when this energy content is substantially below the value just mentioned, the intensity of decoding relay energization will be insufficient to pick up the contacts.

Instead of using static rectifiers of the type shown at 8 and ID in the relay energizing circuits of the equipment of location E in Fig. 1, the necessary rectification of the energizing current supplied to the direct current win-dings of the decoding relays FQ and BQ may be effected mechanically through the medium of a second contact on the code following relay 'IR arranged in the manner shown at H3 at location F in Fig. 1. Each time that this contact is picked up, the Winding of relay FQ is connected With the right half of the secondarywinding of transformer DT through a circuit which extends from the right terminal of that Winding through conductor 20, the winding of relay FQ, conductor 2|, front contact l8 of device TR and conductor 22 back to the mid tap I I of the winding. In consequence, only the positive half cycles of induced transformer voltage are effective to circulate current through the winding of relay FQ.

Likewise, each time that the track relay contact i8 is released, the winding of relay BQ is connected with the left half of the secondary of transformer DT through a circuit which may be traced from the left terminal of the transformer winding through conductor 23, the winding of relay BQ, conductor 24, back contact l8 of relay TR and conductor 22 back to the mid tap ll of the transformer winding. In consequence, only the negative half cycles of induced transformer voltage are effective to produce current flow through the winding of relay BQ.

Instead of using the single decoding trans former which is shown at DT in various views of the drawings, each of the decoding equipment of Figs. 1, 3, 4, 5, 6, '7, 9, 11, 12 and 13 may be modified to use two separate decoding transformers connected with the relays TR, FQ and BQ in the manner represented at DTF and D'IB in Figs. 3a and 3b. In Figs. 3a this two transformer arrangement is provided with static rectifiers 8 and H1 in the transformer output circuits and thus corresponds to Fig. 3 and Fig. 1 location E; in Fig. 3b the arrangement uses a track relay contact it to rectify the energizing current for the decoding relays FQ and BQ and thus corresponds to the scheme which is shown at location F in Fig. 1.

In both instances the two decoding trans formers DTF and DTB are separate units. Each is provided with its own winding supporting core structure which is magnetically independent of that of the companion transformer. From an inspection of the electrical connections it will be seen that the primary winding of transformer DTF replaces the right half of the primary of the single transformer DT of Figs. 1 and 3; that the primary of transformer DTB replaces the left half of that single transformer primary; that the secondary l2 of'device DTF is identical with the correspondingly designated winding of Fig. 3 and replaces the right half of the secondary of transformer DT of Fig, 1; and that the secondary 13 of transformer DTB is identical with the corresponding winding of Fig. 3 and replaces the left half of the Fig. 1 device DT.

From a standpoint of operation, the decoding circuits which are shown in Figs. 3, 3a and 3b and those which are shown at each of locations E and F of Fig. 1 are full equivalents and choice among the five will ordinarily be based only on various features of the application to which the improvements of my invention are to be applied. Since the static rectifiers 8 and II] are separate apparatus, in many cases it is found preferable to employ the mechanical rectifying expedient involving the code following relay contact I8 represented at location F of Fig. 1. This contact, of course, may readily be added to the device TR and the necessary connections thereto are simple and may readily be made.

One advantage of the two transformer arrangement of Figs. 3a and 3b is that the independence of its magnetic circuits allows greater time for collapse of the magnetic flux which is effective to energize each of the decoding relays FQ and BQ and thus somewhat extends the limits of the usable lengths of code periods. Even in the siny gle transformer arrangement, however, the decoding device DT may be of substantially conventional design and its characteristics need be coordinated only with those of relays FQ and BQ and with the lengths of the on and the off periods of the controlling cycles of time code energy which the signalling system employs. These period lengths, in turn, need be restricted only to the extent that they do not greatly exceed the saturating characteristics of the decoding transformer primary circuits. By saturating characteristics as used in this connection is meant the time required for the primary current, when supplied from the direct current source designated by the terminals plus and minus, to reach a steady or non-increasing value when continuously applied.

From the nature of the circuits which supply current to the windings of the transformer fed decoding relays FQ and BQ, it will be seen that both of these windings remain deenergized as long as the contacts of the associated code following relay TR occupy one position continuously and that they are supplied with energizing current only when the track relay is following coded pulses of trackway energy. Moreover, the before mentioned slow.release characteristics of both of these relays are so coordinated with the different codes (SL and L--L in the case of the system of Fig. 1) which are received by the relay TR, that once picked up by a particular one of these codes, the active decoding relay FQ or BQ will span the off periods and hold its contacts continuously picked up as long as the track relay TR continues to receive that particular code.

In effect, therefore, each of the two relays FQ and BQ picks up its contacts only if the recurring pulses of rectified current which its operating winding receives from the transformer DT represent more than a critical portion of the length of the cycles of received trackway code which produces them. In the particular systems disclosed herein, relay FQ responds only if the track relay TR is coding on its front contact about half or more of the time. This means that the contacts of relay FQ are picked up only when a long-on short-off or an equal on-and-oif code is bein received. Similarly, relay BQ becomes sufficiently energized to pick up its contacts only if the track relay is coding on its back contact about half or more of the time. This means that the relay responds only to codes of the short-on-long-ofi or equal on-and-off variety.

Accordingly, when the track relay TR receives no code, the contacts of both of the relays FQ and BQ are released; when energy of the S-L code of Fig. 2 is responded to by the track relay, the contacts of relay BQ are picked up and those of relay FQ are released; when energy of the LS code of Fig. 2 is received, the contacts of relay FQ are picked up and those of relay BQ are released; and finally, when either the L-L or the SS code of Fig. 2 is received by the track relay, the contacts of both of the relays FQ and BQ are picked up. This mode of operation is effected not only by the equipments shown in Figs. 1 and 3 as employin a single decoding transformer DT, but also by the two transformer arrangements of Figs. 3a and 3b.

Considering the particular application of the improvements of my invention which is disclosed in Fig. 1, the two decoding relays FQ and BQ at each of the locations E, F, etc. are arranged to control the lamps of the associated wayside signal S and also to select the coding of the train control energy which is supplied to the rails of the rear track section. The controllin function first named is effected by means of contacts 26 and 21 of the decoding relays while the second named function is effected by the previously mentioned contact 6 of relay B'Q.

As long as the protected stretch of track l-2 is vacant, each of the track relays TR receives energy of the L-L code from the rails of its associated section, both of the relays FQ and BQ are picked up, the wayside signal S shows the clear or green indication and the rails of the section to the rear are supplied with energy of the L-L coding.

Under the conditions stated, lamp G of the wayside signal receives energizing current from the positive terminal of a suitable supply source through front contact 21 of relay BQ, front contact 26 of relay FQ, conductor 28 and the lamp G back to the negative terminal of the supply source. Likewise, under the stated conditions the energizing circuit for the associated track transformer TT includes coding contact LL of device CT. This circuit may be traced from the alternating current supply terminal B through coding contact LL, conductor 29, front contact 6 of relay BQ, conductor 30 and the primary winding of transformer TT back to terminal C of the alternating current supply source.

In the event, now, that a train advances through the protected track stretch, the shunting action of its wheels and axles continuously deenergizes the track relay TR which is associated with each of the occupied sections and causes both of the associated decoding relays FQ and BQ to be released. The controlled wayside signal S accordingly shows stop as a result of lamp R thereof receiving lighting current over a circuit which extends from the positive supply terminal through back contact 2-! of relay BQ, conductor 3| and the lamp R back to the negative supply terminal. At the same time, the rails of the track section to the rear of this signal are supplied with energy of the SL code of Fig. 2' over a circuit which extends from supply terminal B through coding contact SL of device CT, conductor 32, back contact 6 of relay BQ, conductor 30 and the primary of transformer TI back to supply terminal C.

At the location of the first signal behind that contact 6 of relay BQ, conductor 30, the track rails I and 2 and impedance 4 back tothenega-- tive terminal of the track battery.

The lamps of the wayside signal shown at Siin Fig. 5 are selectively supplied with lighting current over circuits controlled by contacts and 21 of relays FQ and BQ. When relay BQ is picked up and relay FQ is in either position, lamp G receives lighting current over a circuit extending from the positive supply terminal through front contact 21 of relay BQ, conductor 28 and the lamp G back to the negative supply terminal; when relay BQ is released and relay FQ. is picked up, lamp Y receives li hting current over. a circuit which extends from the positive supply terminal through back contact 21 of relay BQ, front contact 26 of relay FQ, conductor 33. and the lamp Y back to the negative supply terminal; and whenboth of the relays HQ and FQ are released, lamp. R receives lighting current over a circuit which may be traced from the positive supply terminal through back con tact 21 of relay BQ, back con-tact 26 of relay FQ, conductor 3i and the lamp R back to the negative supply terminal.

The manner of operation of the automatic block signalling system of Fig. 5 is, generally equivalent to that explained in. connection with Fig. 1. As long asthe protected. stretch of track is vacant, each of the track relays TR- receivesenergy of the SL code from the rails of itsassociated section, relay BQ' only is picked up,- the wayside signal S shows the clear or greenindication, and the rails. of the section to the rear are supplied with energy of the S-L coding.

. In the event, now, that a. train advances through the protected track stretch, the shunting action. of its wheels and axles deenergizes the tracklrelay which isassociated with each of. the occupied sections. and causes both of the associated relays FQ and BQ. to. be released. The controlled wayside signal S accordingly shows red or stop and the rails of the track section to the rear of this signal. are supplied with energy of the LS. coding.

At the location of the first signal behind that at the entrance of the occupiedtrack section, relay TR responds to thisL,S code energy and causes decoding relay FQ: only to. pick up. This causes the controlled wayside signal to. show approach or yellow and the rails of the track section to the rear of this signal to. receive energy of the S,-L code.

At the location of the second signal. behind that at the entrance of. the occupied section or track, relay TR responds tothis. S-Lcoded en.- ergy, decoding relay BQ only is picked up, the wayside signal shows clear or green, and. the rails of the rear track section, again. receive energy of the SL code. These conditions are. repeated at succeeding unoccupied'track locations behind the one last discussed above- In using the arrangement oi Fig, 5 (which involves the SL. and the L.S. codes), it is preferable to design the. two relays, FQ and BQ of. each of the decoding equipments. insuchmanner that on a change from one code to the other the originally released relay will pick up before the originally picked up relay drops out. This precaution is advisable to guard against the possibility of the controlled wayside signal S displaying a momentary red flash on the occasion of the change mentioned.

' It will be apparent that the arrangement of at location F in Fig. 1.

Fig. 5, wherein a single coding contact K produces. both the 8-1. and the LS codes, may also be applied to track circuits of the alternatingcurrent energizing. type shown in- Fig. I with the same resulting advantages of code transmitter simplification. In all applications herein disclosed, the operating or driving mechanism: of the transmitter may, of course, be adapted for direct current energizaticn as shown at CT! in Fig. 5 or for alternating current e'nergizationas shown at CT in Fig. 1.

Referring now to Fig. 6', I have there represented at location lvl signal controllingequip-- ment which is a duplicate of that represented The automatic block signalling system of which this equipment forms a part again is. of the three indication type. As in the system of Fig. l, trackway energy coded in accordance with the pattern shown at SL in Fig. 2 produces a yellow or approach 'indication; trackway energy coded in accordance with the pattern shown at LL in Fig. 2; prc-= duces the green or clear indication; and an absence of codeor a reception ofenergy of the LS pattern of Fig, Zcauses the controlledwayside signal S to give the red or stop indication.

At location Ma in Fig. 6-, I have represented a pair of insulated rail joints 3 define a cut section. This cut section may be occasioned by highway crossing signal control, approach control or approach looking, to provide one" block overlap. or for any other purpose where it is necessary to indicate the occupancy or vacancy of a track circuit. without interfering with the normal control of the wayside signal Sm positioned. at the entrance of the signal block. As represented, the cut section Ma is associated with a highway intersection and is employed' to aid the control: of the usual highway crossing protective device (not shown) the operation oi. which isjointly governed by a pair of interlocked-relays XRL and KR?! having contacts 45- and it. In the usual manner these contacts control the completion of the crossing signal operating circuit which is represented as including a conductor 61.

Installed at the next wayside signal location (not shown) ahead ofthe out section 'Mw is equipment which preferably is a duplicateof that shown at locations M and F of Figs; 6and 1. To repeat around the cut section the coded en'- ergy whichthis advance location equipment supplies to the-track rail-s, use is made of the code following track relay 'I'Ra a repeater relay FP- energized over a front contact 48 of relay 'I-Ra; a track transformer TTa for supplying energyirom source BC to the rails of the track section to the rear of the cut locations Ma; and a primary energizing circuit for the transformer which includes contacts 49' and 59 of the relays TRaand FF.

As long as relay 'I'Rd is following a trackway code, contact is thereof intermittently connects the winding of repeater relay F? with a suitablesupply source designated by the terminals plus and minus. characteristics which are suiilciently delayed to bridge the ofi periods of any of the track-- way codes which are normally received atthe out section. Hence, under the conditions stated; it maintains'its contacts picked up; Each time, therefore, that relay TRa responds to a pulse. ofcoded energy, Contact i 'thereof completes for track transformer TTa; an energizing circuit This relay FP has release 7 at the entrance of the occupied track section, relay TR responds to this SL code energy and causes decoding relay BQ only to pick up. The controlled wayside signal S now shows approach as a result of its lamp Y receiving lighting current over a circuit which extends from the positive supply terminal through front contact 21 of relay BQ, back contact 26 of relay FQ, conductor 33 and the lamp Y back to the negative supply terminal. The rails of the track section to the rear of this signal now receive energy of the LL coding as a result of contact LL of device CT being included by front contact 6 of relay BQ in the eenrgizing circuit of the associated track transformer T'I.

At the location of the second signal behind that associated with the occupied section of the track, relay TR responds to this LL coded energy, both of the decoding relays FQ and BQ are picked up, the wayside signal S shows clear and the rails of the rear track section again receive energy of the LL code, all in the manner previously explained in detail.

If cab signalling is desired on the trains which pass through the protected stretch of track |2 of Fig. 1, train carried equipment of the character represented in Fig. 4 may be employed. While this is shown as incorporating the basic arrangement of decoding circuits which is represented at location F of Fig. 1, it will be apparent that it might also use the static rectifier circuits of location E or of Fig. 3.

As shown in Fig. 4, the three lamps G, Y and R of the train carried cab signal CS are selectively supplied with lighting current over circuits which include contacts 26 and 21 of the two decoding relays FQ and BQ. These relays, together with the decoding transformer DT from which they derive operating energy, are carried aboard the train in the usual manner, as is also a master relay MR which corresponds to the code following relay TR of Fig. 1. This master relay is provided with a pole changing contact 35 which controls the primary energizing current of the decoding transformer in the same manner as does contact of device TR. and also with a rectifier contact 36 which performs the function of the contact l8 of the trackway apparatus of Fig. 1.

Master relay MR is shown as being of the usual polarized code following type and the direct current winding thereof receives operating energy from the output terminals of the usual amplifier 31 by way of a master transformer RT. This amplifier, in turn, derives its control energy in the customary manner from the windings 38 of a pick-up device which is mounted on the locomotive front just above and spanning the two track rails I and 2.

When no alternating current from source B-C flows in these rails, the winding of master relay MR is deenergized and the contacts 35 and 36 thereof then occupy the left hand position, shown dotted. However, upon the occasion and for the duration of each pulse of coded energy which flows in the track rails and 2 from a point ahead of the train, relay MR is energized in such manner that it shifts its contacts 35 and 36 to the right hand position, shown in full lines. In this way the contacts follow the trackway code in the same manner as do those of relay TB of the trackway apparatus of Fig. 1.

In operation of the train carried apparatus of Fig. 4, absence of received code produces a released condition of both of the decoding relays FQ and BQ and results in lamp R receiving lighting current over conductor 3|. If the S-L code of Fig. 2 is received from the running rails, relay BQ only is picked up and lamp Y of the cab signal CS then receives lighting current over conductor 33. Finally, if energy of the LL coding of Fig. 2 is received, both of the decoding relays BQ and FQ are picked up and lamp G of the cab signal CS then receives'lighting current over conductor 28.

From the foregoing it will be seen that overlap of cab signals may when desired be used without affecting the basic principles of my decoding scheme herein disclosed. Also, where more than three indications are obtained in the wayside signal, as in Figs. 7, 8 and 11, later to be described, the same decoding circuits and the same or similar extended signal indication circuits may be used for the cab signals as are used for the wayside signals.

Use of my improved .decoding apparatus is by no means restricted to applications involving alternating current track circuits such as are shown in Fig. 1. It is, for example, equally applicable for use with direct current track circuits of the type shown in Fig. 5. Referring to that figure, I have there represented a single signal location I of a three indication automatic block signalling system which incorporates the improvements of my invention. Track circuit energy is supplied from a suitable direct current source shown in the form of a battery 4'0. This energy is coded at one or the other of the two codes shown at SL and LS in Fig. 2 by the single contact K of a direct current code transmitter CTI.

This contact K corresponds to contact SL described in connection with device CT of Fig. 1. By means of a specially shaped cam (not shown) it is continuously actuated between the two positions, shown heavy and dotted in Fig. 5, in a manner that the conductor LS is connected withv the track: battery 40 in accordance with the pattern of the LS code of Fig. 2 and the conductor SL is connected with the battery in accordance with the .SL code of Fig. 2.

Selection of the trackway energy coding is effected by contacts 6 and 4| of the two decoding relays BQ and FQ. When both of these contacts occupy the picked-up position, the rails of the track section to the rear of location I receive energy of the S-L code over a circuit which may be traced from the positive terminal of the track battery 40 through conductor 42, coding contact K in its downward position, conductor SL, front contact 6 of relay BQ, conductor 30, the track rails and 2 and current'limiting impedance 4 back to the negative terminal of the track battery.

Energy of this same S-L code is also supplied to the trackway when either one of the two relays BQ and FQ is picked up individually. In case relay BQ only is picked up, the circuit traced in the preceding paragraph remains effective and in case relay FQ only is picked up, the circuit from conductor SL to conductor 30 includes front contact 4| of relay FQ, conductor 43 and back contact 6 of relay BQ.

In the event that both of the relays BQ and FQ are released, the trackway receives energy of the LS code of Fig. 2 over a circuit which extends from the positive terminal of the track battery 40 through conductor 42, coding contact K in its upward position, conductor LS, back contact 4| of relay FQ, conductor 43, back which extends from the terminal B of the alternating current supply source through front contact 55 of relay FP, conductor 51, front contact 19 of relay TRa, conductor 52 and the primary winding of transformer TTa back to the supply terminal C. In this manner coded energy received from the rails of the track section ahead of location Ma is repeated into the rails of the track section behind that cut section location.

For aiding in the control of the before mentioned highway crossing signals (not shown) the equipment installed at the out section location Ma includes a coding device CTa provided with a contact LS which at times is effective to code the energy supplied to the track section behind the cut section in accordance with the long-short pattern represented at LS in Fig. 2. This coding contact operates constantly and is included in the primary energizing circuit of the track transformer TTa whenever the repeater relay FP releases its contact 56. In that event, the coding circuit extends from the supply terminal B through back contact 56 of relay FP, conductor 53, coding contact LS, conductor 52 and the primary of transformer TTa back to supply terminal C.

Also aiding in the mentioned control of the highway crossing signals is a repeater relay installed at the signal location M and designated by the character X. The energizing circuit of this relay X is so arranged that the relay will be picked up whenever the track relay TR is following code and will be deenergized only when the contacts of the code following device TR occupy one position continuously. To this end the energizing circuit includes a contact 55 of the decoding relay FQ together with contact 21 of relay BQ.

Whenever decoding relay FQ is picked up, the winding of relay X receives energizing current through a circuit which extends from the positive terminal of a suitable supply source through front contacts 65 of relay FQ, conductor 55 and the winding of relay X back to the negative terminal of the supply source. Likewise, when the decoding relay BQ is picked up and relay FQ is released, relay X again receives energizing current over a circuit which may be traced from the positive supply terminal through front contact 2'! of relay BQ, conductor 57, back contact 55 of relay FQ, conductor 58 and the Winding of relay X back to the negative supply terminal.

Consequently, relay X of Fig. 6 is maintained picked up at all times except when the track section M-Ma is occupied. This response is taken advantage of in controlling the highway crossing signals at location Ma. Included in the energizing circuit of operation determining relay XRI is a contact 59 of relay X and included in the energizing circuit for the companion relay XRZ is a contact 60 of the repeater relay FP at the 'cut section. As long as both relays X and FF are energized, the highway signals are maintained inactive.

Assume now that a train advances through the stretch of track shown in Fig. 6. In entering section M-Ma it deenergizes relay TR at location M and all three of the associated relays BQ, FQ and X are released. Contact 59 of relay X deenergizes relay XR! and its contact E completes the operating circuit for the highway crossing signal (not shown) at the cut section Ma. These signals continue to operate until the rear end of the train has cleared the cut section location.

At that time the energy of the LS code from transmitter CTa which the presence of the train in the section beginninwith location Ma causes to be supplied to the rear track circuit is transmitted by the rails of this rear circuit to relay TR. at location M. In responding and picking up relay FQ, it again energizes relay X without disturbing the top aspect of signal Sm. Contact 59 again energizes relay XR! and it breaks at contact 35 the operating circuit for the highway crossing signals and discontinues their operation.

Due to the usual interlocking mechanism (not shown) assumed to be associated with relays ml and XRZ, contact d6 of relay XRZ is mechanically prevented from dropping to the completely released position until the winding of relay XR2 has again been energized. This occurs onlywhen the rear of the train clears the exit end of the signal block of which location M marks the entrance. When that happens both of the relays KB! and XRZ are energized and both contacts .45 and 46 are held picked up to continue the highway crossing signals in the inactive condition.

From an inspection of the circuits of Fig. 6 it will be apparent that a movement of the train in the reverse direction or from right to left in the diagram results in a sequence of operations which is opposite to that just described. That is, relay TRa at location Ma is first deenergized, contact 60 of relay FP then releases to deenergize relay XRZ, and contact 46 thereof completes the operating circuit for the highway crossing signals. As this reverse moving train clears the cut section, relay TRa again responds to the coded energy from ahead, relay FP picks up, contact 66 thereof reenergizes relay XRZ and so on. From this it is evident that other types of crossing signal control circuits may readily be used without altering the essential features of my invention which are disclosed in Fig. 6.

Referring to Fig. 7, I have there represented the equipment at a single signal location 0 of a four indication automatic block signalling system which incorporates the improvements of my invention. The illustrative decoding apparatus employed is a duplicate of that shown at location F in Fig. l and in Figs. 5 and 6.

For the purpose of controlling the four indication signal So use is made of trackway energy of the three different code patterns which are represented at S-L, LL and LS in Fig. 2. These are produced by contacts K and LL of a continuously operating code transmitter GT3. Selection is effected through the medium of contacts and 62 of the decoding relays BQ and FQ.

The particular track circuit represented in Fig. 7 is of the combined direct current and alternating current type. The direct current energy is supplied by a track battery 40 while the alternating current energy is supplied from source B-C through a continuously energized transformer TTl. As the description proceeds, it will be apparent that insofar as the trackway portions of the signalling equipment are concerned, only one of thesources (t6 and BC) is needed.

The particular combination represented is useful in situations wherein it is desired to employ code following track relays TR of the direct current type and also to provide for the control of cab signalling equipment which is responsive only to alternating current energy. For purposes of explanation, it will be assumed that this situ- Accordingly, the track relay TR is shown as being of the direct current type which responds only to trackway energy from the battery at the exit end of the associated section.

For the purpose of selectively energizing the lighting circuits of the four lamps of the wayside signal So, use is made of a contact 2? carried by decoding relay BQ and oi contacts 26, E3 and $4 of relay FQ. in the earlier disclosed embodiment of my invention, lamp lighting current is derived from any suitable source designated by the terminals plus and minus.

In operation of the four indication automatic block signalling system of Fig. 7, as long as the protected stretch of the track l2 is vacant the code following relay TR at each of the Wayside signal locations receives energy of the L-L code from the advance track circuit, both of the decoding relays FQ and BQ are picked up and the controlled signal So displays the clear indication as the result of its lamp G receiving lighting current over a circuit which may be traced from the positive supply terminal through front contact 21 of relay BQ, conductor 65, front contact 26 of relay FQ, conductor 28 and the lamp G back to the negative supply terminal. the stated conditions, the rails ofthe rear track section are supplied with energy of the long-long code pattern shown at L-L in Fig. 2 over a circuit which may be traced from the positive terminal of the track battery through the secondary winding of transformer TTl, conductor 42, coding contact LL of device GT3, conductor 58, front contact 8 of relay BQ, conductor 38, the track rails i and 2, and impedance 4 back to the negative terminal of battery 46.

In the event that a train advances in the direction of the arrow through the protected stretch of the track which is equipped with the signalling apparatus of Fig. '7, the shunting of its wheels and axles deenergizes the track relay TR which is associated with each of the occupied sections. In consequence, the associated decoding relays FQ and BQ are both released and the controlled signal S displays the indication of stop as the result of lamp R thereof receiving lighting current over a circuit which extends from the positive supply terminal through back contact 2! of relay BQ, conductor 67, back contact 64 of relay FQ, conductor 3| and the lamp R back to the negative supply terminal. Under the conditions stated, the rails of the track section to the rear of this signal are supplied by battery 40 with energy of the LS coding over a circuit which may be traced from conductor 42 through coding contact K of device GT3, conductor LS, back contact 62 of relay FQ and back contact 6 of relay BQ back to conductor 3% At the location of the first signal behind that. associated with the occupied section, relay TR responds to this L-S code energy and effects the pick-up of decoding relay FQ only. This causes the controlled wayside signal S to display the approach indication as the result of lamp Y thereof receiving lighting current over a circuit which extends from the positive supply terminalthrough back contact 21 of relay BQ, conductor 6'5, front contact 64' of relay FQ, conductor 33 and the lamp Y back to the negative supply terminal. At the same time, the rails of the track section to the rear of this approach showing signal receive energy of the S--L coding of Fig. 2 over a circuit which extends from conductor 42 through coding contact K in its lowermost position, conductor SL, front contact 62 Under of relay FQ and back. contact 6 of relay BQback to conductor 30.

In responding to this S-L energy, the track relay TR at the succeeding signal location to. the rear effects the pick-up of decoding relay BQ only. This causes the controlled wayside signal S to display the approach restricting indication as a result of both of the two lamps Y of this signal receiving lighting current. The circuit for the upper lamp extends from the positive supply terminal through front contact 27 of relay BQ, conductor 65, back contact 26 of relay FQ, conductor 33 and the lamp Y back to the negative supply terminal. The circuit for the lower lamp Y may be traced from the positive supply terminal through front contact 21 of relay BQ, conductor 65, badk contact 63 of relay FQ, conductor 68 and the lamp Y back to the negative supply terminal. At the same time, the rails of the track section to the rear of this signal receive energy of the LL coding over a circuit which may be traced from conductor 42 through coding contact LL, conductor 66 and front contact 6 of relay BQ back to the conductor 30.

At the location of the third signal behind that associated with the occupied section, relay TR responds to this L-L code energy and picks up both of the relays FQ and BQ. This causes the controlled wayside signal S to display the clear or green indication and the succeeding track circuit to the rear to receive energy of the L-L code pattern, both in the manner explained at the beginning of this description of the way in which the system of Fig. 7 operates.

Referring to Fig. 8, I have there represented means for obtaining a fifth indication in an automatic block signalling system which incorporates the improvements of my invention. Here all four of the code patterns represented in Fig. 2 are produced by the contacts of a transmitting device GT4 at each of the Wayside signal locations and selection among these four codes is effected by means of contacts 6, 62 and 18 of the associated decoding relays HQ and FQ.

As in the case of the earlier disclosed embodiments of my invention, these two relays receive operating energy from the secondary winding of a decoding transformer, designated in Fig. 8, by the character D'I3 through circuits which include a rectifying contact 18 of the same code following relay TR that controls the primary energization of the transformer by means of a contact 1. These portions of the decoding equipment operate in the same manner as has been explained in detail in connection with the earlier figures.

Aiding in the control of the five indication signal S shown at the location U in Fig. 8 is a third decoding relay J. Operating energy for this third relay is supplied from a second secondary winding H of the decoding transformer DT3 through a circuit which includes a transformer JT and a rectifier 13. This transformer JT is provided with a relatively small core and its windings are so arranged that they greatly overenergize' this core and thus cause it to saturate in a comparatively small time. The object of this coordination is to assure that the output energy which it delivers to the winding of the relay J will be the same when the code following relay TR responds to short pulses of coded energy as when it responds to longer pulses of the character utilized by the L-L and the L-S codes of Fig. 2.

' This means that the effective magnitude of the energy which the transformer JT passes to the winding of relay J is almost directly proportional to the number of energy pulses per minute which the received trackway code contains. If this number is comparatively small, as in the case of each of the first three codes represented in Fig. 2, the energy transfer will be insufiicient to pick up relay J. However, when the number is comparatively large, as in the case of the S-S code of Fig. 2. relay J will be energized with sufficient intensity to pick up its contacts and there continuously hold them as long as track relay TR continues to respond to energy of this S-S code.

The six lamps of the five indication signal shown at Su selectively receive energizing current over circuits which include contacts 2! and 16 of relay BQ, contacts 26, TI and 18 of relay FQ and contact 19 of relay J.

In operation of the signalling system of Fig. 8, as long as the protected stretch of the track |-2 remains vacant the code following relay TR at each of the signal locations receives from the rails of the advance track section energy of the S-S code pattern (see Fig. 2), all three of the decoding relays BQ, FQ and J are picked up and the controlled wayside signal S displays the clear indication of green over green.

The lighting circuit for the upper lamp G extends from the positive supply terminal through front contact I6 of relay BQ, front contact 1'! of relay FQ, front contact '19 of relay J, conductor BI and the lamp G back to the negative supply terminal. The circuit for the lower lamp G of the signal may be traced from the positive supply terminal through front contact 21 of relay BQ, front contact 26 of relay FQ, conductor 28 and the lamp G back to the negative supply terminal.

At the same time, the rails of the track section to the rear of each of the controlled wayside signals are supplied with energy of the SS coding over a circuit which extends from the power source terminal B through coding contact SS of device T4, conductor 62, front contact 16 of relay FQ, front contact 6 of relay BQ, conductor 30 and the primary of track transformer TT back to the supply terminal 0.

In the event that a train advances through the stretch of track which is equipped with the signalling facilities of Fig. 8, the shunting action of its wheels and axles deenergizes the track relay TR which is associated with each of the occupied sections. This causes the contacts of all three of the associated relays BQ, FQ and J to be released.

The controlled wayside signal S now displays the stop indication of red over red as a result of both of the lamps R of that signal receiving lighting current. The circuit for the upper lamp R may be traced from the positive supply terminal through back contact 16 of relay BQ, back contact 18 of relay FQ, conductor 83 and the lamp R back to the negative supply terminal.-

The energizing circuit for the lower lamp R of the wayside signal extends from the positive supply terminal through back contact 2'! of relay BQ, conductor 3| and the lamp R back to the negative supply terminal.

Under the conditions stated, the rails of the track section to the rear of this wayside signal are supplied with energy of the L--S coding (see Fig. 2) over a circuit which extends 'fromthe supply terminal B through coding contact K (in its uppermost position) of device GT4, conductor L'S, back contact 62 of relay FQ, conductor 43, back contact 6 of relay BQ, conductor 30 and the primary of transformer TT back to supply terminal C.

In receiving this L-S energy the track relay TR at the entrance of the first vacant block behind the train causes the decoding relay FQ- only to pick up and thereby puts the controlled Wayside signal S at approach or yellow over red. The lighting circuit for the lower lamp R is the same as that previously traced, while that for the upper lamp Y of the signal extends from the positive supply terminal through back contact 16 of relay BQ, front contact 18 of relay FQ, conductor 84 and the lamp Y back to the negative supply terminal.

Under the conditions stated, the rails of the track section to the rear of this wayside signal receive energy of the short-long code pattern which is represented at S-L in Fig. 2. The rail supply circuit now active may be traced from the supply terminal B through coding contact K (in its lowermost position) of device 0T4, conductor SL, front contact 62 of relay FQ,'conductor 43, back contact 6 of relay BQ, conductor 30 and the primary of transformer TT back to the'supply terminal C.

In responding to this S-L energy, the track relay TR at the entrance of the second vacant block behind the train causes relay BQ only of the decodinggroup to pick up. This produces the approach medium or yellow over yellow indication on the part of the controlled wayside signal S. The lighting circuit for the upper lamp Y may be traced from the positive supply terminal through front contact 16 of relay BQ, back contact 71 of relay FQ, conductor 84 and the lamp Y back to the negative supply terminal. The energizing circuit for the lower lamp Y extends from the positive supply terminal through front contact 2! of relay BQ, back contact 26 of relay FQ, conductor 33 and the lamp Y back to the negative supply terminal.

Under the conditions stated, the rails of the track section to the rear of this wayside signal are supplied with energy of the long-longpattern represented at LL in Fig, 2 over a circuit which may be traced from the supply terminal B through coding contact LL of device 0T4, conductor 85, back contact 16 of relay FQ, front contact 6 of relay BQ, conductor 30 and the pri' mary of transformer TT back to supply terminal C.

In receiving this L-L coded energy, the track relay TR at the entrance of the third'vacant block behind the train causes both of the decoding relays BQ and FQ to pick up but is ineffective (as in the case of the S-L and L-S codes) for picking up relay J. Under these conditions the controlled wayside signal S displays the indication of approach restricting or yellow over green. The circuit over which the upper lamp Y of the signal receives lighting current may be traced from the positive supply terminal through front contact 16 of relay BQ, front contact 1! of relay FQ, back contact 19 of relay J conductor 84 and the lamp Y back to the negative supply terminal. The circuit over which the lower lamp G of the signal is lighted extends from the positive supply terminal through front contact 2'! of relay BQ, front contact 26 of re the negative supply terminal.

lay FQ, conductor 28 and the lamp G back to Under .the conditions stated, the rails of the track section to the rear of the signal just mentioned are supplied with energy of the short-short code pattern represented at S-S in Fig. 2. The trackway supply circuit now active extends from the terminal B of the alternating current source through coding contact SS of device T4, conductor 82, front contact of relay FQ, front contact 6 of relay BQ, conductor and the primary of transformer TT back to terminal C of the supply source.

In responding to this SS coded energy, the track relay TR at the entrance of the fourth vacant block behind the train causes all three of the decoding relays BQ, FQ and J to pick up. This puts the controlled wayside signal S at clear or green over green and causes the rails of the track section to the rear of the signal also to receive energy of the short-short code pattern represented at SS in Fig. 2. The lamp energizing and the trackway supply circuits are the same as those traced in an earlier portion of the description relating to the operation of the Fig. 8 apparatus.

In Fig. 9 I have shown a second form of energizing circuit for the decoding relay J of Fig. 8, which relay responds only to the short-short code pattern represented at SS in Fig. 2. Instead of employing the static rectifier shown at 13 in Fig. 8, the arrangement of Fig. 9 makes use of a third contact 81 carried by the code following relay TR and arranged mechanically to rectify the output of the transformer JT which is supplied to the winding of the direct current relay J.

The action of contact 81 is analogous to that of contact [8 which mechanically rectifies the output of the main secondary winding of decoding transformer DT3 and alternately applies 7 the rectified current pulses to the windings of relays BQ and FQ. It differs, however, in that both the positive and the negative half cycles of the alternating current voltage appearing in the'secon'dary winding of transformer JT are eifective to circulate current through the winding of relay J.

Under conditions of positive half cycle production, the winding is connected with the left half of the transformer secondary over a circuit which includes the left terminal of that winding, conductor 88', front contact 81 of relay TR, conductor 89, the winding of relay J and the con ductor 99 back to a mid tap 9| of the winding. Similarly, the circuit which is effective under conditions of negative half cycle production includes the right half of the transformer secondary and may be traced from the right terminal of that winding through conductor 92, back contact 81 of relay TR, conductor 89, the winding of relay J and conductor 90 back to mid tap 9|.

It is thus evident that the mechanical rectifying contact 8'! of Fig. 9 is the full equivalent of the static type of full wave rectifier shown at 13 in Fig. 8. This'being the case, the signalling apparatus of Fig, 8 may employ either the circuits now shown as forming a part of that figure or the modified circuit for decoding relay J which is shown in Fig. 9.

Further regarding the circuits or decoding scheme represented in Fig. 8, it will be apparent that in addition to being used for the five different indications which have just been described, the arrangement is also suitable for providing four indications on the part of the controlled wayside signals S with one code (either L--S or S'L) reserved for track circuit detection (of a character comparable to that explained in con nection with Fig. 6) or for providing three signal indications with two codes reserved for track circuit detection.

In the particular form of decoding circuits which I have represented in Fig. 8, there is a possibility of a flash of the color light signal S on a change from the LS to the SL code or vice versa. For example, if either the BQ or the FQ relay releases its contacts before the companion device picks up its contacts there will be a momentary red fiash; likewise, if the contacts of the newly selected relay are picked up before those of the originally active relay are released, a signal fiash of a less restrictive nature will be produced.

For preventing flashes of this nature under all conditions, use may be madeof the modified scheme represented in Fig. 10. Here the response characteristics of the two relays BQ and FQ are so coordinated that the relay which is originally picked up will release its contacts before the relay which is originally released will pickup its contacts. For bridging the time during which the contacts of both of the relays HQ and FQ are released, a slow acting repeater relay RF]? is employed in the manner shown.

This repeater relay is arranged to be energized when the contacts of relay BQ are picked up and those of relay FQ are released and also when the contacts of relay FQ are picked up and those of relay BQ are released. To this end, its energizing circuit, which again is shown as being associated with a supply source identified by the terminals plus and minus, includes contacts 94 and 95 of relays BQ and FQ which are interconnected in the manner represented. When both of the relays HQ and FQ are picked up, as represented in Fig. 10, the winding of repeater relay BFP is deenergized and its contact 96 occupies the released position.

When relay BQ is picked up and relay FQ is released, the winding of relay BFP receives a steady energizing current over a circuit which may be traced from the positive supply terminal through front contact 9 1 of relay BQ, conductor 91, back contact 95, of relay FQ, conductor 98, the winding of relay BFP back to the negative supply terminal. Similarly, when relay FQ is picked up and relay BQ is released. relay BFP again is energized over a circuit extending from the positive supply terminal through back contact 94 of relay BQ, conductor 99, front contact 95 of relay FQ, conductor 98 and the winding of relay BFP back to the negative supply terminal. In this manner, relay BFP repeats the condition in which either of the decoding relays BQ and FQ is picked up and the other is released.

The four relays shown at BQ, FQ, BFP and J in Fig. 10 are intended to replace the three decoding relays BQ, FQ and J in the system of Fig. .8. The energizing circuits for relays BQ, FQ and J are identical with those shown in Fig. 8 as involving contacts I and [8 of the code following relay TR. the decoding transformer DT3 and the frequency selective transformer JT. Further regarding the circuit for relay J, it may, if desired, be modified in the alternate manner explained in connection with Fig. 9.

When using the arrangement of relays shown in Fig. 10, the code selecting circuits employed likewise will be duplicates of those represented in Fig. 8 in association with the code transmitting device GT4 and including contacts 6, l and 62 of the decoding relays BQ and FQ.

In order to eliminate the before mentioned momentary fiashes of the wayside signal lamps, the lighting circuits for these lamps are modified to the extent represented in Fig. 10. The aspects given by the five indication signal Su are, however, the same as those explained in connection with Fig. 8.

For example, the clear or green over green indication is produced when the track relay TR (Fig. 8) responds to energy of the short-short code pattern represented at SS in Fig. 2 and eifects the pick-up of relays BQ, FQ and J. The circuit through which the upper lamp G receives lighting current under this condition may be traced from the positive supply terminal through back contact 96 of relay BFP, conductor Hll, front contact I02 of relay BQ, conductor I03, front contact I04 of relay FQ, conductor )5, front contact 19 of relay J, conductor BI and the lamp G back to the negative supply terminal. The lighting circuit for the lower lamp G extends from the positive supply terminal through front contact 21 of relay BQ, front contact 26 of relay FQ, conductor 28 and the lamp G back to the negative supply terminal.

As in the case of Fig. 8, also, the approach restricting or yellow over gree indication is displayed when the track relay TR responds to energy of the long-long code pattern represented at LL in Fig. 2, and thus picks up relays BQ and FQ only of the four decoding devices represented in Fig. 10. The lighting circuit for the upper lamp Y of the wayside signal S extends from the positive supply terminal through back contact 96 of relay BFP, conductor I01, front contact I02 of relay BQ, conductor Hi3, front contact I94 of relay FQ, conductor I05, back contact 19 of relay J, conductor 84 and the lamp Y back to the negative supply terminal. The energizing circuit for the lower lamp G remains the same as that last traced above.

The controlled Wayside signal S shows the approach medium indication of yellow over yellow when energy of the short-long coding shown at SL in Fig. 2 is received from the trackway to cause relays BQ and BFP of the four decoding devices shown in Fig. to be picked up. The lighting circuit for the upper lamp Y now extends from the positive supply terminal through front contact 96 of relay BFP,

. conductor 84 and the lamp Y back to the negative supply terminal. The lighting circuit for the lower lamp Y may be traced from the positive supply terminal through front contact 21 of relay BQ, back contact 26 of relay FQ, conductor 33 and the lamp Y back to the negative supply terminal.

The approach or yellow over red signal indication results when energy of the long-short code pattern, represented at LS in Fig. 2, is received from the trackway to pick up relays FQ and BFP only of the four decoding devices shown in Fig. 10. Under this condition the upper lamp Y of the controlled wayside signal S continues to be lighted over the circuit traced in the preceding paragraph and the lower lamp R is energized over a circuit extending from the positive supply terminal through back contact 21 of relay BQ, conductor 3| and the lamp R back to the negative supply terminal.

Finally, the stop or red over red signal indication results when the track relay IR (Fig. 8)

fails to receive coded energy and thus allows the contacts of all four of the decoding devices shown in Fig. 10to be released. The circuit over which the upper lamp R of the signal is lighted under this condition may be traced from the positive supply terminal through back contact 96 of relay BFP, conductor l0l, back contact I02 of relay BQ, conductor I01, back contact I08 of relay FQ, conductor 83 and the lamp R back to the negative supply terminal. The lighting circuit for the lower lamp R remains the same as that traced therefor in the preceding paragraph.

From the foregoing description of the circuits of Fig. 10 through which the lamps of the wayside signal S selectively receive lighting current, it will be apparent that, with the signal aspects set forth above, the upper head of the signal holds a yellow indication until after the lower head changes from red to yellow or vice versa. This is because the contact 96 of relay BFP which is included in the circuit of the upper yellow lamp is arranged to stay continuously picked up during the time that the picked up condition is shifted from relay BQ to relay FQ or vice versa. This action results from the slow releasing characteristics of relay BFP which are so chosen as to bridge the time just referred to.

For example, assume that the signal S is displaying yellow over yellow as a result of relays BQ and BFP being picked up and relay FQ being released. In changing to the yellow over red indication, relay BFP holds its contact 96 continuously picked up while relay BQ releases and relay FQ picks up and transfers the lighting circuit for the lower signal head from lamp Y to lamp R and at the same time transfers the energizing circuit for the winding of relay BFP from conductor 9'! to conductor 99. Likewise, in changing back to the yellow over yellow indication, relay BFP again remains continuously picked up while the contacts of relays BQ and FQ transfer the relay energizing circuit from conductor 99 back to conductor 91. In this manner the possibility of a flash of the color light signal S on a change from the LS to the SL code or vice versa is eliminated.

In dealing with other types of signals or other arrangements of aspects which present somewhat diiferent problems, use may, of course, be made of different though generally equivalent methods to prevent momentary flashes should any preventive means of this character be required. Regardless of the type of signal that may be used, whether color light, position light, semaphore or otherwise, the fundamental operation of my improved decoding circuits herein disclosed need not be altered and the only changes necessary for the different adaptations will be confined to the signal circuits themselves.

Referring now to Fig. 11,- I have there represented an adaptation of the improvements of my invention to a system of automatic block signalling which provides six different indications on the part of each of the wayside signals. As shown at the single location W, each of these signals S conveniently may include two heads of three lamps each.

For coding the trackway energy which operates the code following track relay TR at the entrance end of each of the signal block sections, use is made of a code transmitter GT5 which is provided with four coding contacts K, 15, I29 and i813, arranged for selective inclusion in the circuit through which the track transformer TT connected with the rails of the section to the rear of each signal receives energy frOm the alternating current source B-C. Contact K is arranged to produce one or the other of the two time codes represented at L-S and S L in Fig. 2. The remaining three contacts produce other codes of the conventional frequency variety in which the on and off periods are of substantially equal length. To facilitate explanation, it will be assumed that the I contact produces a code of 75 energy pulses per minute, the I20 contact acode of 120 pulses per minute and the I80 contact a code of 180 energy pulses per minute.

The decoding equipment associated with the track relay TR at each of the signal locations includes the two time code responsive relays BQ and FQ energized over rectifying contact I8 of device TR from the secondary winding of decoding transformer DTI in the same manner as at location F in Fig. 1. Likewise, this decoding transformer DTI receives primary energizing current under the control of pole changing contact 'I of relay TR in the same manner as in the preceding figures. It differs, however, in being provided with an extended primary section I III which is included in a circuit through which a pair of frequency selective circuits DUIZII and DUISI) are energized by the voltage which appears across the entire length of the primary winding.

Through these frequency selective circuits the windings of decoding relays J I20 and J I80 are supplied with operating current by way of the usual full wav rectifiers III and H2. Circuit DUI2II is resonant only to code pulse rates of 120 cycles per minute and in consequence relay J I20 picks up its contacts only when energy of the I29 coding is being received from the trackway. Similarly, circuit DUIIIH is resonant only to code pulse rates of 180 cycles per minute and, as a result, decoding relay J I60 picks up only when. relay TR. responds to trackway energy of the I80 coding.

The first mentioned or time code responsive decoding relays BQ and FQ are respectively picked up upon reception of trackway energy of the short-long or SL code pattern and of the long-short or L--S pattern shown in Fig. 2. In addition, both of these relays respond to a reception of any one of the three frequency codes (equal on and off) of '75, 120 and 180 energy pulses per minute. Because of the resonant character of circuit DUIZII, the third decoding relay J IZB responds only to energy of the I20 coding and is insensitive to that of the L-S, S--L, I5 and I80 pattern. Likewise, because of the resonant characteristics of circuit DUISII, the fourth decoding relay J I80 responds only to energy of the 180 pulse per minute trackway code and is insensitive to all of the remaining four codes which are produced by device GT5.

Selection of which one of these five codes is supplied to the rails of the rear track circuit is made through the medium of contacts 6, I0, IIS, H4 and H5 of the four decoding relays. Likewise, selection of the aspect which the controlled wayside signal Sw displays is made through the medium of contacts 21, H6, H1, II8 and H9 of relays BQ, FQ, JIZII and JI80, which contacts are included in the lighting circuits of the six lamps of the signal.

In operation of the six indication automatic block signalling system represented in Fig. 11, as long as the protected stretch of track I2 remains vacant, the code following relay TR at the entrance end of each of the track sections receives energy of the I86 coding and causes relays BQ, F'Q and J I to pick up their contacts. Under these conditions, the controlled signal S displays the clear indication of green over green as a result of the upper lamp G receiving lighting current over a circuit which includes front contacts 21 and H8 of relay BQ and J Hill and the lower lamp G receiving lighting current over a circuit which includes front contacts H6 and I I9 of relays FQ and JIIiIl.

Under the conditions stated, th rails of the track section to the rear of each of the wayside signals S receive energy of the I89 coding over a circuit which may be traced from. the supply terminal B through coding contact I80 of device CT5, conductor I22, front contact H5 of relay J I80, conductor I23, front contact III of relay FQ, front contact 6 of relay BQ, conductor 30 and the primary of transformer TT back to the supply terminal C.

When a train advances through the protected stretch of the track, the shunting action of its wheels and axles deenergizes the track relay TR at the entrance of each of the occupied sections. As a result, all four of the associated decoding relays release their contacts and the controlled Wayside signal S displays the stop indication of red over red. The lighting circuit for the upper lamp R. extends from the positive supply terminal through back contact 21 of relay BQ, conductor I24 and the lamp R back to the negative supply terminal. The energizing circuit for the lower lamp R extends from the positive supply terminal through back contact IIS of relay FQ, conductor I25 and the lamp R back to the negative supply terminal.

Under th conditions stated, the rails of the track section to the rear of the stop displaying signal are supplied with energy of the long-short code pattern represented at LS in Fig. 2. The rail supply circuit now active may be traced from the supply terminal B through coding contact K (when in its uppermost position) of device 0T5, conductor LS, back contact II3 of relay FQ, conductor I26, back contact 6 of relay BQ, conductor 30 and the primary of transformer T1 back to supply terminal C.

In receiving and responding to this L-S coded energy, the track relay TR. at the entrance end of the first vacant signal block behind the train causesonly the associated decoding relay FQ to pick up. The controlled wayside signal S now displays the approach indication of red over yellow, the upper lamp R receiving lighting current over the circuit traced above and the lower lamp Y being energized over a circuit which extends from the positive supply terminal through front contact IIB of relay FQ, conductor I21, back contact H9 of relay J I89, conductor I28, back contact II! of relay J I20, conductor I29 and the lamp Y back to the negative supply terminal.

Under the conditions stated, the rails of the track section to the rear of this approach showing signal are supplied with energy of the short long pattern represented at SL in Fig. 2. The rail supply circuit now active extends from supply terminal B through coding contact K (when in its lowermost position) of device GT5, conductor SL, front contact II-3 of relay FQ, conductor I26, back contact 6 of relay BQ, conductor 30 and the primary of transformer TT back to supply terminal 0.

In responding to this SL code, track relay at'the'entrance end of the second vacant signal'block behind the train causes relay BQ only of the decoding group to pick up. Under these conditions, the controlled wayside signal S shows the approach medium? indication of yellow over red. The upper lamp Y now receives energizing current over a circuit extending from the positive supply terminal through front contact 21 of relay BQ, conductor I3I, back contact II8 of relay J I80 and the lamp Y back to the negative supply terminal. The lighting circuit of the lower lamp R includes back contact IIB of relay FQ and conductor I25.

Under the conditions stated, the rails of the track section to the rear of the referred to signal are supplied with energy of the 75 pulse per minute coding over a circuit which extends from the supply terminal B through coding contact I of device GT5, conductor I32, back contact III of relay FQ, front contact 6 of relay BQ, conductor 30 and the primary of transformer T'I back to supply terminal 0.

In responding to this energy of the 75 coding, the track relay TR at the entrance end of the third vacant signal block behind the train causes relays BQ and FQ of the decoding group to pick up their contacts. The controlled signal S now shows the approach restricting indication of yellow over yellow as a result of the upper lamp Y receiving lighting current over the circuit traced above and the lower lamp Y also being lighted over the circuit previously traced as including front contact IIG of relay FQ, back contact II9 of relay JIGIJ and back contact III of relay JI20.

Under the conditions stated, the rails of the track section to the rear of the referred to signal receive energy of the 120 pulse per minute coding over a circuit which may be traced from the supply terminal B through coding contact I20 of device GT5, conductor I33, back contact II4 of relay J I 20, conductor I34, back contact II5 of relay J I80, conductor I23, front contact III of relay FQ, front contact 6 of relay BQ, conductor 39 and the primary of transformer TT back to supply terminal C.

In responding to this 120 coded energy, the

track relay TR at the entrance end of the fourth vacant signal block behind the train causes all three of the decoding relays BQ, FQ, and J I20 to pick up their contacts but does not affect the fourth relay J I89. The controlled Wayside signal now shows the caution indication of yellow over green as a result of the upper lamp Y receiving lighting current over a circuit previously traced as including front contact 21 of relay BQ and back contact I I8 of relay J I80 and'the lower lamp G also receiving lighting current over a circuit which extends'from the positive supply terminal through front contact H6 of relay FQ, conductor I27, back contact H9 of relay J I80, conductor I28, front contact II! of relay J I28, conductor I36 and the lamp G back to the negative supply terminal. Under the conditions stated, the rails of the track section to the rear of the referred to signal are supplied with energy of the 180 pulse per minute coding over a circuit which extends from the supply terminal B through coding contact I80 ofdevice GT5, conductor I22, front contact II4 of relay J I20, conductor I34, back contact II5 of relay J ISII, conductor I23, front contact III ofrelay FQ, front contact I; of relay BQ, conductor 30 and the primary of transformer TT back to supply terminal 0.

' In responding to this energy of the 180 coding,

the track relay TR at the entrance end of the fifth vacant signal block behind the train causes relays BQ, FQ and J I to pick up their contacts 7 and allows relay J I2II to remain released. This produces the before described clear indication of green over green on the part of the controlled wayside signal S and also causes the rails of the track section to the rear of that signal again to receive energy of the coding over a circuit also previously traced.

In addition to providing six signal indications in the manner just explained, the decoding combination represented in Fig. 11 is also suited for use in five indication automatic block signalling systems where it is desired to reserve one code for track'circuit detection of the character discussed in connection with Fig. 6. By the same token, of course, it may be used to provide four signal indications in situations where it is desired that two codes be reserved for track circuit detection.

j Referring now to Fig.,12, I have there represented the basic decoding scheme (first disclosed in Figs. land 3) incorporated in a five indication system of automatic block signalling wherein the coded energy is transmitted over aline circuit comprised of conductors I40 and MI instead of through the track rails I and 2 as in the earlier disclosed applications. Theorganization of apparatus represented at the single signal location N is, of course, duplicated at each of the remaining signal locations which the protected stretch of track includes and the line circuit I 4IJ-I4I interconnects adjacent location equipments in the usualmanner.

Theenergy transmitted to each signal location by this line circuit is received by the primary winding of a decoding transformer DTL which as in Fig. 3, is provided with two separate secondary windings I2 and I3. Winding I2 supplies decoding relay FQ with a rectified measure of the energy content of the positive half cycles of secondary voltage through a circuit which includes a static rectifier 8 and winding I3 similarly supplies decoding relay BQ with a rectified measure ofthe negative half cycles of secondary voltage through a circuit which includes a rectifier I0.

The source of the energy which the line circuit I 40I4I transmits to the transformer DTL is shown as being a battery I42. Current from this battery is coded by one or another of the contacts K and LL of a code transmitter 0T3 andits transmission to the decoding equipment in the rear is controlled by a pair of contacts I43 and I44 of a track relay 'TRb which is operated by energy received from the running rails I2 of the track section in advance of the location. The coding device GT3 is adapted to supply any one of the threecodes represented at S L, L-L and L -S in Fig. 2, selection being made through the medium of contacts 6 and 62 of decoding relaysBQ and FQ in a manner comparable to that explained in connection with Fig. 7; I

In the illustrative form represented, the track circuits for the automatic block signalling system of Fig. 12 are continuously energized from a source of direct current shown in the form of a track battery I46 which is directly connected with the rails I and 2 of each signal block sec,- tion at the exit end thereof over a circuit which includes the usual current limiting'impedance 4.

' As long as the track section is vacant, the rails thereof transmit energy from this battery I46 to the winding of the track relay TRb at the entrance end thereof and in this manner the relay holds its contacts I43 and I44 in the represented pick-up positions in which the line circuit conductors I40 and MI are connected with the coded energy supply circuit which includes battery I42 and coding device GT3. When, however, a train comes into the section, the shunting action of its wheels and axles deenergizes the track relay, which releases its contacts and disconnects the line circuit I45I4I from the coded energy supply facilities.

Conveniently, each of the controlled Wayside signals may be of the six lamp color light type represented at Sn and when such is the case, control of the lamp lighting circuits is effected through the medium of contacts I41 to I52, inclusive, of relays TRo, BQ and FQ.

In operation of the signalling equipment of Fig. 12, as long as the protected stretch of the track I-2 remains vacant, the track relay TRb at the entrance end of each of the sections is picked up and the associated coding facilities supply the line circuit I40I4I with energy of the long-long code pattern represented at LL in Fig. 2. In receiving this LL coded energy, each of the decoding transformers DTL causes both of the relays BQ and FQ to pick up their contacts. each of the locations (of which N is representative) now shows the clear or green over green indication.

The lighting circuit for the upper lamp G of the signal may be traced from the positive terminal of a suitable supply source through front contact M! of relay TRb, conductor I53, front contact I40 of relay BQ, front contact I5I of relay FQ and the lamp G back to the negative supply terminal. The circuit for the lower lamp G of the signal extends from the positive supply terminal through front contact I48 of relay TRb, conductor I54, front contact I50 of relay BQ and the lamp G back to the negative supply terminal. The circuit referred to above through which the primary winding of decoding transformer DTL is supplied with energy of the LL coding may be traced from the positive terminal of the supply battery I42 at the next location in advance through frontcontact I43 of relay 'IRb, line conductor I40, the primary winding of transformer DTL, line conductor I4I, front contact I44 of relay TRb at the forward location, conductor I55, coding contact LL of device CT3, conductor 66, front contact 6 of relay BQ and conductor I56 back to the negative terminal of the supply battery I42. 7

As a train advances through the protected stretch of the track, the shunting action of its wheels and axles deenergizes the track relay TRb associated with each of the occupied sections. Contacts I43 and I44 of this relay now disconnect the rear extending line I40-I4I from the coding facilities and contacts I41 and I48 cause the controlled wayside signal S to display the stop or red over red indication. The lighting circuit for the upper lamp R, extends from the positive supply terminal through back con tact I4'I of relay TRb, conductor I51 and the lamp R back to the negative supply terminal. Similarly, the lighting circuit for the lower lamp R includes back contact I48 of relay'TRb and conductor I58.

Due to the disconnecting action of the line controlling contacts I43 and I44 of relay TRb of the The controlled wayside signal S at i occupied track section, the decoding transformer DTL at the entrance end of the first vacant section behind the train is deenergized and both of the decoding relays BQ and FQ are accordingly released. Track relay TRb at that rear location is, however, picked up by the energy which the rails I and 2 thereof transmit from the track battery I46 at the advance location.

Under these conditions, the wayside signal S at the entrance of the first vacant section behind the train displays the-approach indication of yellow over red as a result of the upper lamp Y of the signal receiving lighting current over a circuit which includes front contact I4'I of relay TRb, back contact I49 of relay HQ and conductor I55 and the lower lamp R receiving lighting current over a circuit which includes front contact I48 of relay TRb, conductor I54, back contact I50 of relay BQ and back contact I52 of relay FQ. At the same time, the rearwardly extending line circuit I40I4I receives energy of the LS coding over a circuit which includes front contact I44 of relay TRb, conductor I55, coding contact K of device 0T3, conductor LS, back contact 62 of relay FQ, back contact 6 of relay BQ, conductor I56, the battery I42, and front contact I43 of relay TRb.

At the entrance of the second vacant section behind the train, relay TRb is again picked up, the decoding transformer DTL receives this energy of the LS coding and by it decoding relay FQ is picked up, relay BQ remaining released. The controlled wayside signal S now shows the approach medium indication of yellow over yellow as the result of the upper lamp Y of the signal receiving lighting current over a circuit which includes front contact I41 of relay TRb, conductor I53, back contact I49 of relay BQ and conductor I59 and the lower lamp Y also-receiving lighting current over a circuit which includes front contact I48 of relay TRb conductor I54, back contact I50 of relay BQ and front contact I52 of relay FQ.

Under the conditions stated, the rearwardly extending line circuit I40--I4I receives energy of the S-L coding over a circuit which includes front contact I44 of relay TRb, conductor I55, coding contact K (when in its lowermost position) of device GT3, conductor SL, front contact 62 of relay FQ, back contact 6 of relay BQ, conductor I56, the battery I42 and front contact I43 of relay TRb.

At the entrance end of the third vacant section behind the train, relay 'I'Rb is again picked up, the decoding transformer DTL receives this .energy of the S--L coding and by it the decoding relay BQ only is picked up. Under these conditions, the controlled wayside signal S displays the indication of approach restricting or yellow over green as the result of the upper lamp Y being energized over the circuit described above and the lower lamp G being lighted over front contact I48 of relay TRb, conductor I54 and front contact I50 of relay BQ. At the same time, the rearwardly extending line circuit I40-- both of the decoding relays BQ and FQ are picked up to cause the controlled wayside signal S again to display the clear indication of green over green and the rearwardly extending line circuit Mil-Ml to be supplied with energy of the longlong code pattern represented at LL in Fig. 2.

Referring to Fig. 13, I have there represented a modified form of decoding apparatus for use in a system of the type shown in Fig. 12. Instead of connecting the primary of the decoding transformer DTL directly to the line conductors I40 and HM, the winding of a code following line relay LR receives the energy transmitted by these conductors and through contacts 1 and i8 thereof it controls the energization of a decoding transformer DT from which the two decoding relays BQ and FQ receive operating energy in the same manner as at location F of Fig. 1.

Relay LR. follows the pulses of coded energy in the same manner as does relay, TR of the earlier figures and contact I pole changes the primary current sup-plied to transformer DT while contact is mechanically rectifies the output of the secondary winding of this transformer and causes the winding of relay FQ to receive a measure of the energy content of the positive half cycles of the secondary voltage and the winding of relay BQ to receive a measure of the energy content of the negative half cycles of the secondary voltage. These decoding relays BQ and FQ thus respond in the same manner as when connected as shown in Fig. 12 and in this way they perform the necessary code selecting and signal aspect determining functions which are disclosed make use of the delayed response decoding relays BQ and FQ which respectively receive rectified measures of the positive and the negative half cycles of secondary voltage of the decoding transformer DT, which in turn, is energized in accordance with the energy pulses of one or another of the code patterns of Fig. 2.

My improved decoding scheme around which these signalling systems are built thus will be seen to obtain selectivity mainly by comparing the energy contents of the positive and the negative half cycles of the secondary voltage of the decoding transformer. As compared with time code schemes of the prior art which employ only the retardation characteristics of slow acting relays, my new scheme is found to be superior in that it reduces the power consumption of the decoding apparatus, it lowers the first cost of the apparatus itself and it substantially broadappended claims Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a railway signalling system, the combination of a source of coded energy, a decoding transformer provided with a direct current input circuit, means including a code following contact for completing said circuit in step with the pulses of said coded energy, an output circuit for said transformer, a half Wave rectifier forming a part of said output circuit, and a decoding relay provided with a winding connected to receive rectified current from said output circuit,.said relay having slow acting characteristics so chosen that the relay responds only when the cycles of said coded energy have on and off periods of predeterminedly related lengths.

2. In combination, means for producing coded energy, a device having a contact which operates in step with the pulses of said energy, decoding transformer means energized over a direct current primary circuit which is controlled by said 7 contact, a first slow acting decoding relay energized by current which results from the positive half cycles only of the output voltage of said transformer means, and a second slow acting decoding relay energized by current which results from the negative half cycles only of said transformer output voltage.

3. n combination, means for producing coded energy, a device having a contact which operates in step with the pulses of said energy, decoding transformer means energized over a primary circuit which is controlled by said contact, and first and second decoding relays provided with windings respectively energized by the positive half cycles only and by the negative half cycles only of the output voltage of said transformer means and having delayed response characteristics which are predeterminedly coordiinated with the lengths of the on and the off periods in the cycles of said coded energy.

4. In combination, means for producing coded energy, a device having a contact which operates in step with the pulses of said energy, a decoding transformer energized over a direct current circuit which includes said contact, a pair of output circuits for said transformer, a half Wave rectifier connected in one of said circuits in a manner to transmit current due only to the energy content of the positive half cycles of the transformer output voltage, a half wave rectifier connected in the other of said circuits in a manner to transmit current due only to the energy content of the negative half cycles of said voltage, and a first and a second decoding relay respectively connected in said first and said second out-put circuits and having delayed response characteristics predeterminedly coordinated with the lengths of the on and the off periods in the cycles of said coded energy.

5. In combination: means for producing recurrent cycles of coded energy; a device having a contact which operates in step with the pulses of said energy; decoding transformer means energized over a primary circuit which is controlled by said contact; first and second output circuits for said transformer means; a rectifier included in each of said circuits and respectively so poled that the first circuit passes current due only to the positive half cycles of the output voltage of said transformer mean-s and the second circuit passes current due only to the negative half cycles of that voltage; and a first and a second decoding rel-ay respectively connected in said first and said second output circuits and having de layed response characteristics so coordinated that one relay respond-s when the on periods in the cycles of said coded energy are relatively long, the other when the off periods in said cycles are relatively long and both when said on and off periods are of substantially equal lengths.

6. Railway traffic controlling apparatus comprising a' code following relay, decoding transformer means energized over a direct current primary circuit which is pole changed .by said relay, a first slow acting decoding relay energized by the positive half cycles only of the output voltage of said transformer means, a second slow acting decoding relay energized by the negative half cycles only of said transformer output voltage, and trafiic governing means controlled by said decoding relays.

7. In a railway signalling system, the combination of a code following relay, a transformer energized over a pole changing circuit which is controlled by said relay, a pair of slow acting decoding relays energized from said transformer, half wave rectifying means connected in the energizing circuit of one of said decoding relays to cause the intensity of its effective energization' to vary with the energy content of the positive half cycles only of the output voltage of said transformer, and half wave rectifying means connected in the energizing circuit of the other of said decoding relays to cause the intensity of itseffective energization to Vary with the energy content of the negative half cycles only of said transformer output voltage.

8. In a railway signalling system, the combination of a code following relay, a transformer energized over a circuit which is controlled by said relay, an output circuit for said transformer, a contact carried by said code following relay and connected in said output circuit to act as a half wave rectifier of the current which flows therein, and a decoding relay provided with a winding which receives said rectified current and having delayed response characteristics which enable the relay to distinguish differences in the relative lengths of the on and the off periods of recurrent cycles of coded energy to which said code following relay may respond.

9. In combination: a code following relay provided with a pole changing contact and with a current rectifying contact; a decoding transformer energized over a direct current circuit which includes said pole changing contact and provided with a pair of output circuits which include said current rectifying contact and which are arranged to transmit current respectively due only to the energy of the positive half cycles and only to the energy of the negative half cycles 1 the transformer output voltage; and a first and a second decoding relay respectively connected to receive rectified energy from said first and said second output circuits and having delayed response characteristics so coordinated that one relay responds when the on periods of the coded energy cycles which operate said code following relay are relatively long, the other whenthe off periods of said cycles are relatively long, and both when said on and off periods are of substantially equal lengths.

10. In a railway trafiic controlling system, the combination of a circuit which is coextensive with a section of the right-of way, means for supplying coded energy to the conductors of said circuit, means controlled by traffic conditions acid-72c for varying the relative lengths of the on" and the off periods in the cycles of said energy, transformer means energized in step with coded energy pulses which are received from said circuit, a first slow acting decoding relay energized by the positive half cycles only of the output voltage of said transformer means, a second slow acting decoding relay energized by the negative half cycles only of said output voltage, and traffic governing means controlled by said decoding relays.

11. In a railway signalling system, the combination of a circuit which is coextensive with a section of the right of way, means for supplying coded energy to the conductors of said circuit, means controlled by traffic conditions for varying the relative lengths of the on and the off" periods in the cycles of said energy, a code following relay operated by energy received from said circuit conductors, a transformer energized over a primary circuit which is controlled by said relay, a first slow acting decoding relay energized by the positive half cycles only of the output voltage of said transformer, a second slow acting decoding relay energized by the negative half cycles only of said output voltage, and traffic governing means controlled by said decoding relays.

12. In a railway signalling system, the combination of a section of track, means for supplying coded energy to the rails of said section, means controlled by advance traific conditions for varying the relative lengths of the on and the off periods in the cycles of said energy, a code folio wing relay operated by energy received from said rails, transformer means energized over a primary circuit which is controlled by said relay, a first slow acting decoding relay energized by the positive half cycles only of the output voltage of said transformer means, a second slow acting decoding relay energized by the negative half cycles only of said output voltage, and traflic governing means controlled by said decoding relays.

13. In combination with a section of track, means for supplying coded energy to the rails of said isection; means governed by advance traflic conditions for varying the relative lengths of the on and off periods in the cycles of said energy, a code following relay operated by energy received from said rails, a decoding transformer energized over a primary circuit which includes a pole changing contact of said relay, a first slow acting decoding relay energized by the positive half cycles only of the output voltage of said transformer, a second slow acting relay energized by the negative half cycles only of said output voltage, and a traffic governing signal positioned at the entrance of said track section and controlled by said decoding relays.

14. In a railway traffic controlling system, a traffic track, means for supplying coded energy to the rails of said track, means controlled by traffic conditions for varying the relative lengths of the on and the off periods in the cycles of said'energy, a track relay connected to said rails and adapted to pick up upon and for the duration of each pulse of energy received therefrom and to remain released at all other times, a decoding transformer energized over a direct current circuit which'includes a contact of said track relay, a first slow acting decoding relay energized by current resulting from the positive half cycles only of theo'utput voltage of said transformer, a second slow acting decoding relay energized by current resulting from the negative half cycles

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