US2114899A

US2114899A - Railway traffic controlling apparatus

Info

Publication number: US2114899A
Application number: US743743A
Authority: US
Inventors: Charles W Failor
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1934-09-12
Filing date: 1934-09-12
Publication date: 1938-04-19
Anticipated expiration: 1955-04-19

Description

April 19, 1938. c. w. FAILOR 2,114,899

RATLWAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 12, 1954 6 Sheets-Sheet l ELM? r Hui. \MNQSNNQQW W 3% 9% 9% g A 5% g g g Charles ll). FCZZZOP QQQ i A n.

HIS ATTORNEY H3 I I l j I] lulu nufl luau ANQQ. la E 5 E Q II l Ill. ANQ. VI ofl in IL 3% .lulo lo lino Halo lulu F5 r. 1 .l .Ua v5 nl b m nl V E Hmw PM N SEQ R QL w b N B Q T m u b QEQ LA EQ m b 1 Q N D w 6 April 19, 1938. c. w. FAlLOR 2,114,899

RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 12, 1954 e sheets-sheet 2 Code Seleozzon INVENTOR cf Charles LUFaz lop v BY 6mm HIS ATTORNEY.

C. W. FAILOR RAILWAY TRAFFIC CONTROLLING APPARATUS A rifi 19, was.

Original Filed Sept. 12, 1934 6 Sheets-Sheet 3 Amplifier Unit INVENTOR Charles LU. Failop 0101*" LDDD HIS ATTORNEY April 19,1938. c. w. FAILOR RAIILWAY TRAFFIC CONTROLLING APPARATUS 6 Sheets-Sheet 4 Q HE INVENTOR Charles LU.FailoP. BY Chi VFW] 4, H15 TATTORNEY' l j o I!!! Q Mum-wan I. ll o Hi ly, Y m m @225 68% @225 Ew b w s bl m w w w w b TXwS w 4 a April 19, 1938. c.'w. FAILOR RAILWAY TRAFFIC CONTROLLING APPARATUS 6 Sheefs-Sheet 5 Original Filed Sept. 12, 1934 If] R EM 1 Y m U m6 m N NW N U m w P -Y mu m mm 0 F n I A w s m Rm i a m Y April 19, 1938. c. w. FAILOR RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 12, 1934 6 Sheets-Sheet 6 Qsv MU a Sm m kwww 33 FL m HIS ATTORNg b QE Patented Apr. 19, 1938 I 2,1143% UNITE STATES PATENT DFFIQE RAILWAY TRAFFIC CONTROLLING APPARATUS Charles W. Failor, Forest Hills, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania,

Application September 12, 1934, Serial No. 743,743 Renewed April 22, 1936 19 Claims. (Cl. 246-34) My invention relates to railway traffic convide distinctive wayside and cab signal indica trolling apparatus, and more specifically to aptions, in accordance with traffic conditions in five paratus for controlling wayside and/or cab sigblocks in advance. It will be noted that the feanals by means of coded trackway energy. ture which distinguishes one code from another I will describe a few forms of apparatus emmay be any one or more of the following: A difbodying my invention, and will then point out the ference in the duration of the on intervals; a novel features thereof in claims. difference in the duration of the off intervals;

In the accompanying drawings, Fig. 1 is a diaor a difierence in the duration of the code cycles. grammatic view showing several types of code Another distinguishing characteristic of the codes suitable for use with apparatus embodying my which I use is that the unit code cycles follow 10 invention. Fig. 2 is a chart showing the condieach other regularly or periodically, there being tion of each individual relay of a decoding group no periodic interruption or other variation inof my apparatus, under various code conditions, terposed between groups of code cycles.

and also showing the manner in which the codes Having described the codes themselves, I shall of Fig. 1 are distributed in a number of blocks to nextpoint out how these codes are allocated in 15 the rear of an occupied section for providing a the various blocks of a section of railway track five-indication, four-block signal system. Fig. 3 to provide a five-indication, four-block signal sysis a diagrammatic view showing the wayside portern. The code distribution is best seen in the tion of the apparatus for a five-indication, fourchart of Fig. 2 which shows a section of track a f block signal system embodying my invention. divided into block sections a.b b-c, etc. Block Fig. 4 is a diagrammatic view showing the 1000- e is intersected by a highway at location e 20 motive equipment associated with the wayside so that this block is divided intothe two track apparatus of Fig. 3, and also embodying my insections ee' and e -f for the purpose of clearvention. Fig. 5 is a chart, similar to the chart of ing out the highway crossing apparatus when a Fig. 2, but showing the code and relay conditions train passes location 6 5 for a four-indication, three-block signal system. With a train occupying section e f, as indi- 2 Figs. 6 and '7 are diagrammatic views showing the cated on the drawings, code 1 is supplied to seewayside and the locomotive equipment, respection ee and signal S indicates R/R, showing tively, for a four-indication, three-block signal that there is a train within the limits of block 0 system embodying my invention. Figs. 8 and 9 e-f. Block de receives code 2, and consequentare diagrammatic views showing the wayside and ly signal S indicates Y/R, showing that there is the locomotive equipment, respectively, for a one clear block in advance. Similarly, blocks four-indication, three-block signal system emc-d, bc, and 11-41 receive

codes

3, 4, and 5, rebodying my invention. Figs. 10 and 11 are diaspectively, so that signal f3 indicates Y/Y, signal grammatic views showing the wayside and loco- S indicates G/Y, and signal S indicates G/G. 35 motive equipment, respectively, for a modified The indications Y/Y, G/Y, and G/G correspond, form of a three-indication, two-block signal sysrespectively, to two, three, and four (or more) tem, also embodying my invention. clear blocks in advance. The manner in which Similar reference characters refer to similar these codes are established in the various blocks, parts in each of the several views. in accordance with traffic conditions in advance, 40 Referring first to Fig. 1, the codes shown therewill be understood from a description of Fig. 3. in comprise alternate on and off current in- On the chart of Fig. 2, at each of the signal tervals which are repeated periodically to provide locations a, b, 0, etc., is shown a vertical group recurrent code cycles. Code 1 is made up of curof contact fingers, each contact finger of this 4.5 rent impulses or on intervals of short duration, group representing diagrammatically a particular separated by short off intervals. Code 2 is decoding relay such as TR, TP, TPA, etc., of the made up of short on intervals separated by wayside decoding relay group shown at the leftlong off intervals. In code 3, the on intervals hand portion of Fig. 3. A contact finger shown are long, and are separated by short ofi interin the horizontal position indicates that under vais. In code 4 on the other hand, both on and the code condition existing at that location, the 50 off intervals are of long duration. Finally, in particular relay for which that contact stands code 5, the code cycle comprises a long on inis maintained energized. For example, at location terval followed by a short off interval, and fole, contact finger 8 indicates that relay TP is up. lowed in turn by a short on interval and a long The down position of contact finger 9, for exofi interval. These five codes are used to proample, indicates that relay HA is released. The 55 up position of contact finger ID, with the down position shown dotted, indicates that relay TR is following code; that is, relay TR is alternately energized to its up position and released to its down position. By means of the chart of Fig. 2, therefore, the condition of any decoding relay when operating on any one of the codes of Fig. 1 can be determined at a glance.

Referring now to Fig. 3, this figure shows the code transmitting apparatus for the block e-f of Fig. 2, as well as the decoding and transmitting apparatus at location e of the above figure. The apparatus at location e is typical of the apparatus at the other locations a, b, 0, etc., so that a description of the apparatus for one block will be sufiicient for an understanding of the operation of the system as a whole.

The rails 6 and I of the section e f in which trafi'ic normally moves from left to right in the direction of the arrow, are supplied with alternating current from the secondary winding of a track transformer T which has a primary winding energized from an alternating current source having the terminals BXCX. The current supplied to the primary winding of transformer T is controlled over one or another of the

contacts

2, 3, 4 and of the constantly operating code transmitter GT as determined by the code selection apparatus which is not shown in detail, but which is controlled by traific conditions in advance in a manner which will be clearly understood from a description of the apparatus at location e.

Code transmitter CT is so designed that contact 2 is alternately closed for a short interval, and open for a long interval, thus producing code 2 of Fig. 1. Similarly, contact 3 which produces code 3, is alternately closed for a long interval and open for a short interval. In

like manner contacts

4 and 5 establish code 4 and code 5, respectively. In its usual embodiment, code transmitter CT will comprise a group of motor driven cams cooperating with the

movable contact fingers

2, 3, 5 and 5, and having swells or grooves suitably arranged around the periphery of the cam to produce the codes which are illustrated. Any other apparatus suitable for timing the current impulses in accordance with a group of predetermined time codes may, of course, be used.

Connected across the rails of location e is the control element H of a two-element, alternating current code following track relay TR which controls the energization of a pair of repeating relays TP and TPA over its contacts |2|3 and 2-id, respectively. Relays TP and TPA are of the direct current type and are sufliciently slow releasing to bridge the open circuit interval of contacts l 2! 3 and l2l4, respectively, when relay TR is following any one of the codes shown in Fig. 1. That is, relays PP and TPA both remain energized whenever relay TR is following code and both become deenergized when relay TR is shunted by a train, or is permanently released due to any other cause, such as a broken wire, failure of the power supply, broken down insulated rail joint, etc. The circuit for relay TP includes the front contact l2l3 of relay TR a miniature relay transformer TTP, and a rectifier RTP. The circuit for relay TPA includes back contact l2M of relay TR front contact #5 of relay TF miniature transformer TTPA, and rectifier RTPA. Relays TF and TPA serve to check the integrity of relay TR since a failure of this relay to release due to a mechanical defect or false energization will result be clear from the description which follows.

in the release of relay TPA Furthermore, a broken wire or a broken rail will cause contact |2-l3 to remain open, releasing both relays TF and TPA to provide a warning of the fault.

As long as relay TR is following the code being supplied to section e this code will be repeated into section ee over a circuit starting at one terminal BX of the alternating current source, wire l6, contact l2|3 of relay TR wires I! and [8, front point of contact [9 of relay TPA wire 20, and the primary winding of transformer T to the other terminal CX of the source. Therefore, whenever section e -f is unoccupied, both sections ee and e f will receive the same code, which may be any one of

codes

2, 3, 4 or 5, as determined by trafiic conditions in advance of location I. Section ee in addition to the four codes listed above and originating in code transmitter GT may also receive code 1 which is produced by the auxiliary code transmitter CT whenever section e -,f is occupied.

Assuming that a train occupies section e -f, all three relays TR TP and TPA will be re leased, so that code transmitter GT will become energized over back contact 2i of relay TPA whereupon code 1 will be supplied to transformer T over the following circuit: Contact l of code transmitter CT wire 22, back point of contact 59 of relay TPA and wire 20. It should be pointed out that signal S is not responsive to code 1, this code being used in Fig. 3, solely for the purpose of clearing out the highway crossing signal XS at location e in a manner which will Obviously, code 1 can be used for the control of any suitable track detection apparatus, being in no manner limited to the control of highway crossing apparatus.

When code 1 is supplied to section ee track relay TR will follow the impulses of this code and will supply an energizing impulse alternately to relays TP and TPA, over its contacts |2l3 and lZ-M, respectively. Relays TP and TPA are sufliciently slow releasing to bridge the short off and short on periods, respectively, of code 1, but the retardation of relay TP is insuflicient to bridge the long 01f periods of

codes

2, 4 or 5, for example. Similarly, relay TPA is insufiiciently retarded to bridge the long on periods of

codes

3, 4, or 5, for example. As long as relay TR is following code 1, therefore, both relays TP and TPA are maintained energized. Since relay TP is energized, relay H will also be energized, over front contact 23 of relay 'I'P. This condition is depicted in the chart of Fig. 2, at location e, where it is seen that signal S indicates R/R; relay TR is following code 1; relays TP, TPA, and H are energized; and the remaining relays of the decoding group are all deenergized.

Vfith relays H and TPA both energized, a circuit is completed for energizing the highway crossing control relay which circuit may be traced from one erminal 13 of a suitable current source, front contact 25 of relay H, wire 26, front contact 25 of relay TPA, line wire 27, and winding of relay ZIP... to the other terminal C of the source. Relay will therefore pick up, opening its back contact 28 to dcencrgize ie highway crossing signal XS. It will be apparent from the foregoing description that as soon as a train vacates section ec and code i is supplied to the rails thereof, the operation of the highway crossing ap aaratus will be discontinued.

The entry of a train into section e-e initiates the operation of signal XS by opening the circuit for relay XR at front contact 24 of relay H, through the sequential release of relays TR, TP, and H. Since relays DP and DDP are both deenergized, whenever section ef is occupied, signal S will indicate R/R, by virtue of a circuit for the upper lamp R which includes the back point of contact 29 of relay DP, wire 30, and the back point of contact 3! of relay DDP; and a circuit for the lower lamp R which includes the back point of contact 32 of relay DP, wire 33, and the back point of contact 34 of relay DDP. Under this condition, code 2 will be supplied to the rear section over contact 2 of code transmitter CT, wire 35, back point of contact 38 of relay DDP, wire 31, back point of contact 33 of relay DP, and wire 39, to track transformer T.

When the train vacates section e -f, the code selection apparatus at location f will cause code 2 to be supplied to the track transformer T Relay TR will follow this code, and relays TP and TPA will both be energized, so that contact l2l3 of relay TR will repeat code 2 into section cc Relay TR will follow the impulses of code 2, and in so doing will maintain relay TPA energized. However, since the duration of the off interval of code 2 is longer than the release time of relay 'IP,this relay will release once during each code cycle. Relay H will be maintained energized, as before, by the current impulses which it receives over the front point of contact 23 of relay TP. Each time that relay TP releases, relay D will receive an impulse of current over the back point of contact 23 of relay TP, wire Ml, and front contact 4| of relay H. Relay D is sufficiently slow releasing to bridge the energized interval of relay TP, so that relay D is maintained energized. Since front contact d2 of relay D is closed, relay DP is also energized.

Summing up the relay operations efiective when code 2 is supplied to section ee it is found that relays TR and TP are following code; relays TPA, H, D, and DP are all energized; and relays HA, DD, DDP, and DDD are all deenergized. (This corresponds to the condition illustrated at location at in the chart of Fig. 2.) Since relay DP is energized and relay DDP is deenergized, signal S will now indicate Y/R, by virtue of a circuit for the upper lamp Ywhich includes the front point of contact 29 of relay DP, wire $3, front contact 44 of relay D, wire 45, back point of contact it of relay DDP, and wire 41; and a circuit for the lower lamp R which includes Wire 53, the front point of contact 32 of relay DP, wire 49, front contact 50 of relay D, wire 5|, back point of contact 52 of relay DDP, and wire 54. Cod-e 3 will be supplied to the rear section over contact 3 of code transmitter CT, wire 55, back point of contact 56 of relay DDP, wire 51, front point of contact 38 of relay DP, and wire 33 to transformer T.

When the train clears the block in advance of location 1', code 3 will be supplied to section ee Since code 3 has along on interval, relay TPA will now follow code, and relay TP will be maintained energized. Relay H will be energized, as before, but relay D will be deenergized due to the fact that the circuit for relay D is open at the back point of contact 23 of relay TP. Consequently, relay DP will also be deenergized. The code operation of relay TPA will cause an impulse of current to be supplied to relay HA each time that the back point of contact 58 of relay TPA closes. Since the retardation of relay HA is suflicient to bridge the energized interval of relay TPA, relay HA will be maintained energized, causing relay DD to be picked up over a circuit which includes the front point of contact 58 of relay TPA, wire 59, front point of contact 60 of relay HA, and wire 6!. Relay DDP will now be picked up over the front contact 62 of relay DD.

Summarizing the relay conditions obtaining when code 3 is supplied to section ee it is found that relays TR and TPA are following code; relays TP, H, HA, DD, and DDP are all energized; and relays D, DP, and DDD are all deenergized. (This corresponds to the condition illustrated at location c in the chart of Fig. 2.) Since relay DDP is energized and relay DP is deenergized, signal S will indicate Y/Y, by virtue of a circuit for the upper lamp Y which includes the back point of contact 29 of relay DP, wire 30, front point of contact 3! of relay DDP, and wires 63 and 41; and a circuit for the lower lamp Y which includes wire 48, back point of contact 32 of relay DP, wire 33, front point of contact 34 of relay DDP, and

wires

64 and 65. Code 4 will be supplied to the rear section over contact 4 of code transmitter CT, wire 66, front point of contact 33 of relay DDP, wire 31, back point of contact 33 of relay DP, and wire 39.

When the train clears the second block in advance of location code 4 will be supplied to section ee Since code 4 has both a long on interval and a long off interval, both relays TP and TPA will follow code, whereupon relays H, D, and DP, as well as relays HA, DD, and DDP will all be picked up, in a manner which will be clear from the description already given. Relay DDD will now be the only relay of the group which is not energized. (This condition is illustrated at location b of Fig, 2.) Since relays DP and DDP are both energized, signal S will indicate G/Y, by virtue of a circuit for the upper lamp G which includes the front point of contact 29 of relay DP, wire 53, front point of contact M of relay D, wire 45, front point of contact 46 of relay DDP, wire 61, front contact 68 of relay DD, and wire 69; and a circuit for the lower lamp Y which includes wire 48, front point of contact 32 of relay DP, wire 49, front contact 55 of relay D, wire 5!, front point of contact 52 of relay DDP, wire 13, back point of contact 1! of relay DDD, and

wires

12 and 65. Code 5 will be supplied to the rear section over contact 5 of code transmitter CT, wire l3, front point of contact 56 of relay DDP, wire 51, front point of contact 38 of relay DP, and wire 33.

When the train clears the third block in advance of location 1, code 5 will be supplied to section e-e Since code 5 has both a long on interval and a long off interval, it will be readily apparent that both relays TP and TPA will follow code. However, the effect of the short off interval which follows each long on interval is to supply an added impulse of current to relay TPA, thus prolonging the energized time of this relay beyond the time which relay HA is capable of bridging, whereupon relay HA will release during each cycle of the code. That is, relay HA will release before the back point of contact 58 of relay TPA closes to re-energize relay HA. It will be apparent, therefore, that there is a time interval in each code cycle of code 5 during which the front point of contact 58 of relay TPA and the back point of contact 50 of relay HA as well as front contact 99 of relay DD are all closed, thus cornplcting an energizing circuit for relay DDD. Relay DDD is sufficiently slow releasing to remain picked up under the condition of intermittent energization just described.

As a result, under the influence of code 5, relays TR, TP, TPA, and HA will follow code, and the remaining relays will all be energized. (This condition is illustrated at location a of Fig. 2.) Signal S will now indicate G/G by virtue of a circuit for the upper lamp G which is identical with the circuit traced for this lamp in connection with operation on code 4, and a circuit for the lower lamp G which includes wire 43, front point of contact 32 of relay DP, wire 49, front contact 59.: of relay D, wire 5!, front point of contact 52 of relay DDP, wire 10, front point of contact H of relay DDD, and wire M. Code 5 will be supplied to the rear section over the identical circuit traced for this code in connection with the operation of the relay group on code 4.

From the foregoing description it will be apparent that I have provided a five-indication. four-block signal system having a high degree of foreign current protection, with provision for track circuit clearing at out sections in a posi tive and safe manner by means of a distinct code which does not affect signal operation. This system embodies all of the safety features which are deemed essential in apparatus of this character. Since the track relays are of the two-element type, the instantaneous relative polarities of adjoining track circuits may be staggered, as indicated in Fig. 3, for the purpose of providing broken down insulated rail joint protection.

Although the track circuits of Fig. 3 are shown supplied with alternating rail current, this requirement is not essential because, if direct current code following track relays are substituted for he alternating current track relays TR, direct current codes can be used, as well.

If the relays 'IP and TPA at location 6 of Fig. 3 are of the alternating current type, transformers TTP and TTPA, as well as rectifiers RTP and RTPA may be eliminated. One reason for not using alternating current relays in this connecticn is that the required time characteristics are more readily and more inexpensively obtained with direct current relays.

It will be observed that relays DP and DDP at location c of Fig. 3 merely repeat the position of relays D and DD, respectively, and are therefore not essential from the standpoint of operativcness, since, fundamentally, the same results can. be obtained by adding contacts to relays D and DD. However, since relays D and DD are required to retain accurate time characteristics, it is desirable to reduce the number of contacts opby these relays as much as possible, to prevent contact wear and changes in adjustment from affecting the timing. Furthermore, the use of separate relays DP and DDP permits added retardation of pickup as well as release to be obtained, which aids in eliminating undesired signal flashes which might otherwise occur when the signal is changing from one indication to another.

With reference to code 5, since the purpose of the short off interval is to delay the release of relay TPA sufficiently to force relay HA to release and thereby to follow code, this interval can be same manner whether code 5 is used, or an alternative code comprising long on, long off, short on, short off" intervals is employed.

Having described the operation of the Wayside equipment for a five-indication, four-block system, I shall now describe the locomotive-carried cab signaling apparatus associated with this system and shown in Fig. 4.

Referring to Fig. 4, the master relay MR is energized through the amplifier unit A, by means of current induced in the two receiver coils RC associated with the track rails 6 and 7. Relay MR is a code following relay which follows the on, and off intervals of the codes illustrated in Fig. i. Relays MRP, LH, and LD correspond to the left-hand decoding group of relays TP, H, and D, of Fig. 3. Similarly, relays MRPA, LHA, LDD, and LDDD, correspond to relays TPA, HA, DD, and DDD of the right-hand decoding group of Fig. 3. The repeating relays DP and DDP of Fig. 3 have no counterpart on the locomotive, but may of course be used, if desired. The sequence of operation of the locomotive decoding relays n the various codes is similar to the operation of the wayside group of Fig. 3, and will be clear without added description.

When relay MR is following code 1, relays MRP, MRPA, and LH will all be energized, and the remaining relays will all be deenergized. With relays LD and LDD both deenergized, the cab signal CS will indicate R, the circuit for the R lamp being obvious from the drawings. The R indication will also be given in the absence of rail current, or if the rail current is steady or unccded, for the reason that under these conditions relay MR will not be following code, and relays LD and LDD will both be deenergized.

When relay MR is following code 2, relay MRP will also be coding; relays MRPA, LH, and LD will all be energized; and the remaining relays will all be deenergized. With relay LD energized, and relay LDD deenergized, the cab signal CS will indicate Y.

With code 3 supplied to the rails, relays MR and MRPA will follow code; relays MRP, LH, LHA, and LDD will all be energized; and relays LD and LDDD will be deenergized. With relay LDD energized and relay LD deenergized, cab signal CS will indicate Y/Y. When relay MR is following code 4:, relays MRP and MRPA will both be following code, and all of the remaining relays with the exception of relay LDDD will be energized. Cab signal CS will indicate G/Y, over the back point of contact 75 of relay LDDD, and the front points of contacts T and T! of relays LDD and LD, respectively. With code 5 supplied to the rails, relays MR, MRP, MRPA and LHA will follow code, and all of the remaining relays will be energized. Cab signal CS will, therefore, indicate G/G, over the front points of contacts 15, 16, and 'l'! of relays LDDD, LDD, and LD, respectively.

Referring now to Fig. 5, this figure shows a chart, similar to the chart shown in Fig. 2, for a four-indication, three-block signal system which employs the first four codes of Fig. 1. Code 1 is used for clearing out highway crossing apparatus, as before, and

codes

2, 3, and 4 are used for signal control. The allocation of the four codes to the blocks in the rear of an occupied section, as well as the condition of each decoding relay under the various code conditions, are shown in the chart of Fig. 5. The wayside decoding apparatus for the four-indication, three-block system is shown in Fig. 6.

Referring now to Fig. 6, the general arrangement of the decoding relays is the same as that shown in Fig. 3, with the exception that relay DDD is omitted, this relay being necessary only when code is used. When relay TR is following code 1, relays TP, TPA, H, and HA are all energized, and the remaining relays are all deen-.

ergized. Therefore,

front contacts

24 and 18 of relays H and HA, respectively, will be closed, thus energizing Tine wire ill for clearing out highway crossing apparatus. Since relays DP and DDP are both deenergized, signal S will indicate R/R, and code 2 will be supplied to the rear section, by virtue of circuits which will be clear from the drawings without further description. This condition is pictured at location 7' of Fig. 5.

When relay TR is following code 2, relay T? will also follow code; relays TPA, H, HA, D, and DP will all be energized, and relays DD and DDP will be deenergized. With relay DP energized and relay DDP deenergized, signal S will indicate Y/R and code 3 will be supplied to the rear section. If relay TR is following code 3, relay TPA will also follow code; relays TP, H, HA, DD and DDP will all be energized; and relays D and DP will be deenergized. With relay DDP energized and relay DP deenergized, signal S will indicate Y/G and code 4 will be supplied to the rear section. Similarly, if relay TR is following code 4, relays TP and TPA will both follow code, so that all of the relays of the decoding group will be energized, whereupon signal S will indicate G/R. The rear section will receive code 4, as before.

Referring to Fig. 7, the apparatus shown therein is the locomotive equipment associated with the Wayside equipment of Fig. 6. The operation of this apparatus is identical with the operation of the apparatus of Fig. 4, previously described,

except that code 5 is not used since this code is unnecessary when but four indications of the cab signal are required. The indications of cab signal CS of Fig. '7 are R, Y, Y/G, and G, which result from response to

codes

1, 2, 3, and 4, respectively.

Referring now to Fig. 8, this figure shows the wayside apparatus for a four-indication, threeblock system, similar to Fig. 6, but employing direct current track circuits, and making use of steady or uncoded energy for track circuit detection.

Codes

1, 2, and 3, respectively, are used to provide the Y/R, Y/G, and G/G indications of signal S. Block mn is divided into the two out sections art-m and m n, due to the presence of the highway intersection at location m The code following track relay TR. is a two-position, polarized relay, biased to the down position in the absence of current, or in the presence of current of reverse relative polarity. When a train enters section 27Zm relay TR becomes deenergized and releases relay HP. When relay HP releases, its front contact it removes energy from line wire 2i, thus releasing relay KR to initiate the operation of crossing signal XS, in wellknown manner. The relays H, D, and DP will also be deenergized, so that signal S will indicate R/R. Code 1 will, therefore, be suppliedto the rear section by virtue of code operation of code repeater relay CTP, which is supplied with current of code 1 over contact i of the constantly operating code transmitter CT, wires 8! and 82, back point of contact 83 of relay DP, and wire 84.

When the train clears section mm steady energy will be received by relay TR, due to the closing of the back point of contact 85 of relay TP Relay TR will therefore pick up, closing the front contact 19 of relay HP to energize relay XR for clearing out the highway crossing apparatus. The pickup of relay TR will cause relay HP to pick up, but this will entail no change in the indication of signal S, or in the code which is supplied to the rear section.

When the train clears section m n, code 1 will be supplied to this section over a circuit controlled by the code selection apparatus at location it, which circuit is identical with the code supplying circuit at location m. Relay TR will follow code i. and will maintain relay TP energized, Whereupon code 1 will be relayed to section mm over front contact 86 of relay TR and front point of contact 85 of relay TP Relay TR will also follow code 1, and in so doing will maintain relays HP, and DP energized. Relays H and D will remain deenergized, because these relays have a slow pickup interval suflicient to bridge the operation of relay TR on code 1. Under the above condition, signal S will indicate Y/R; and code 2 will be supplied to relay CTP and therefore to the rear section, over contact 802 of code transmitter CT, wire 81, back point of contact 88 of relay H, wire 89, back point of contact 93 of relay D, front contact iii of relay HP, front point of contact 83 of relay DP, and wire 84!.

When the train clears the first block in advance of location 11., relay TR will follow code 2, and since relay TP is sufficiently slow releasing to bridge the long off interval of code 2, this code will be repeated into section mm Relay TR in following code 2 will maintain relays HP and DP picked up, as before, and in addition, will pick up relay H, due to the fact that the oil interval of code 2 is sufficiently long for pickup of this relay. Relays H and D are sufficiently slow releasing, in addition to being slow pickup relays, to bridge the long on interval of code 3, and the long ofi interval of code 2, respectively. Relays HP and DP are sufficiently slow releasing to bridge the long off intervals of code 2, and the long on intervals of code 3, respectively.

Since relay D requires a long on interval for pickup, this relay will remain deenergized when relay TR is following code 2, and under this condition, signal S will indicate Y/G. Code 3 will be supplied to relay CTP over contact 8fi3 of code transmitter CT, wires 92 and 93, front point of contact 88 of relay H, wire 89, back point of contact 90 of relay D, front contact 9! of relay HP, front point of contact 83 of relay DP, and wire 84.

When the train clears the first two blocks in advance of location n, relays TR and TR will follow code 3. Since code 3 contains a short off interval, relay H will be deenergized; and since this code has a long on interval, relay D will be energized. Relays DP and HP will both be energized, as before. Under this condition, signal S will indicate G/R, and code 3 will again be supplied to the rear section.

It will be apparent from the above description of Fig. 8 that, by using the time codes of Fig. l and introducing a time interval into the pickup of certain decoding relays, a relatively simple four-indication,three-block system is obtained, which system requires fewer decoding relays than the corresponding system of Fig. 6, in which decoding depends upon the release times of certain relays of the decoding group. The system of Fig. 8 is not limited to direct current track circuits, being capable of use on alternating current track circuits, as well. If cab signaling apparatus responsive to timed impulses of direct current is used, the wayside apparatus of Fig. 3 may remain unaltered. However, if an alternating carrier current is preferred due to more elhcient response of the cab signalling apparatus, then the secondary winding of a track transformer may be connected in series with the track battery in well-known manner, for supplying the needed alternating current carrier for the code impulses.

The locomotive equipment associated with the wayside equipment of Fig. 8 is shown in Fig. 9. The general operation of the decoding relay group of Fig. 9 will be clear from the description of Fig. 8 previously given. When relay MR is following code 1, relays LHP and LDP are picked up, and relays LH and LD are deenergized, so that cab signals CS will indicate Y. On code 2, relays LHP, LDP, and LH will be picked up, and relay LD will be deenergized, whereupon signal CS will indicate Y/G. On code 3, relays LHP, LDP, and LD will be up, and relay LH will be down, so that signal CS will indicate G. When the rails 3 and l are supplied with steady energy, relay MR will not operate, so that all four relays of the locomotive decoding group will be deenergized. Under this condition, signal CS will indicate R.

The decoding principles of Fig. 8 can also be applied to a three-indication, two-block system, and one such system is shown in Fig. 10. Steady or uncoded energy is used for track detection, and

codes

1 and 3 are used for providing the Y and the G indications, respectively. Code 2 is not used, although, if desired, code 2 may be substituted for code 3 by a simple rearrangement of the decoding relay circuits, which change will be obvious from the foregoing description of Fig. 8.

Referring to Fig. 10, I shall first assume that a train has entered section qq Relays TR, 'IP, H, and D will all be deenergized, so that signal S will indicate R. Code 1 will be furnished to section p-q, over contact I of code transmitter CT, and the back point of contact 94 of relay TP. As soon as the train clears section p-q completely, relay 'I'R will follow code 1, and will pick up relays PP and H Relay D will remain deenergized because this relay has a pickup time longer than the short on interval of code 1. Code 3 will therefore be furnished to the block in the rear of location p, and signal S will indicate Y.

When the train enters section q q the opening of front contact 96 of relay 'I'R will deenergize the crossing control relay 25%, thus initiating the operation of crossing signal XS. Also, the opening of front contact 95 of relay 'I'R will remove code from the rails of section qq so that relay TR will remain deenergized even after the train clears section q--q As soon as the train enters section q r, relay TR will release, releasing relay TP and causing steady energy to, be supplied to section q -q over the back point of contact 9'! of relay TP Once the train clears section q q relay TR will pick up on the steady energy, picking up relay XR to clear out the crossing signal XS. The closing of contact 95 of relay TR causes steady energy to be applied to section q--q so that relay TR will pick up, but this will bring about no change in the indication of signal S nor in the code being supplied to section p--q.

When the train clears section q r, code 1 will be supplied to this section and will be repeated into section q q over front contact 98 of relay TR and the front point of contact 9'! of relay TF Relay TR will repeat the code into section qq so that relays H and T? will become energized. Relay D Will remain deenergized. Under this condition, signal S will indicate Y, and code 3 will be supplied to section p-q. Code 3 will cause relays TP H and D to become energized, so that signal S will indicate G.

When the train clears the first block in advance of section q -r, this section will receive code 3, and this code will be repeated successively into sections q -q and qq Relays H, TP, and D will thereupon all be picked up, so that signal S will indicate G.

The locomotive apparatus associated with the wayside apparatus of Fig. 10 is shown in Fig. 11. The operation of this apparatus on

codes

1 and 3 will be clear, without detailed description, from the foregoing explanation of Fig. 10.

In conclusion, it will be observed that I have provided a system of coded wayside and/or cab signaling employing time codes characterized by uniform recurrence of the fundamental code cycle which is used for signal selection, without any interruption or other variation being interposed periodically between groups of the fundamental code cycles. In this manner, the particular part of the code cycle at which energy is first applied to the decoding relay group becomes of no importance, since the code is uniform and not cyclic in character. Also, a uniform code of this character is readily obtainable with an oscillating type of code transmitter, without the necessity for motor driven cams. As will be apparent from the detailed description and drawings, decoding may be obtained either by timing the release of the decoding relays, or by timing the pickup of these relays. Track detection may be obtained either by using code, or by using steady energy. It will be apparent also, that by combining certain of the codes illustrated in Fig. 1, additional codes similar to code can be obtained, for increasing the number of signal indications above five, and the number of blocks controlled above four.

Although I have herein shown and described only a few forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track, means for supplying the rails of said section with coded current of one of a group of time codes selected in accordance with traffic conditions in advance of said section, each of said time codes comprising a unit code cycle which is repeated uniformly without cyclic variation, the unit code cycles in the individual time codes of said group being characterized by a difference in the relative as well as the absolute duration of the on and off intervals of said unit cycle, a code following track relay for said section capable of following the on and off intervals of said unit code cycles, a group of decoding relays controlled over a circuit which includes a contact of said track relay and having slow acting characteristics timed for selective response in accordance with the time code being supplied to said section, and trafiic governing apparatus controlled by said decoding relays.

2. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively long intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a track relay for said section capable of following said energy impulses, a pair of decoding relays controlled by said track relay in such manner that one but not the other decoding relay will release during each of said energy intervals of long duration, and that said other but not said one decoding relay will release during each of said long intervals of no energy, and tramc governing apparatus controlled by said decoding relays.

3. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively long intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a track relay for said section capable of following said energy impulses, a first relay controlled over a front contact of said track relay and capable of bridging said short but not said long intervals of no energy, a second relay controlled over a back contact of said track relay and capable of bridging said short but not said long energy impulses, a third relay controlled over a front contact of said first relay and capable of bridging the code operation of said first relay, a fourth relay controlled over a back contact of said second relay and capable of bridging the code operation of said second relay, and traffic governing apparatus controlled by said third and fourth relays.

4. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively long intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a track relay for said section capable of following said energy impulses, a first relay controlled over a front contact of said track relay and capable of bridging said short but not said long intervals of no energy, a second relay controlled over a back contact of said track relay and capable of bridging said short but not said long energy impulses, a third relay controlled over a front contact of said first relay and capable of bridging the code operation of said first relay, a fourth relay controlled over a back contact of said second relay and capable of bridging the code operation of said second relay, a fifth relay controlled over a back contact of said first relay and a front contact of said third relay, a sixth relay controlled over a front contact of said second relay as well as a front contact of said fourth relay, and traf fic governing apparatus controlled by said fifth and sixth relays.

5. In combination, a stretch of railway track divided into blocks one of which includes a highway intersection and a first and a second cut section for controlling highway crossing apparatus at said intersection, means effective when a train occupies the first block in advance of said one block for supplying the rails of said second cut section with current of a first code comprising short on intervals separated by long off intervals, means eifective when a train occupies the second block in advance of said one block but is clear of said first block for supplying the rails of said second cut section with current of a second code comprising long on intervals separated by short 01f intervals, means for repeating into said first cut section the code which is supplied to said second cut section, means effective, when a train enters said second cut section for supplying the rails of said first cut section with current of a third code comprising short on intervals separated by short 01f intervals,,a code'following track relayfor said first cut section, a first relay controlled over a front contact of said track relay and capable of bridging the short 01f intervals of said second code but not the long 01f intervals of said first code, a second relay controlled over a back contact of said track relay and capable of bridging the short on interval of said first code but not the long on interval of said second code, a third relay controlled over a front contact of said first relay and capable of bridging the code operation of said first relay, a fourth relay controlled over a front contact of said second relay and capable of bridging the code operation of said second relay, trafiic governing apparatus controlled by said third and fourth relays, a

highway crossing control relay, and a circuit for said control relay including a front contact of said third relay and a front contact of said second relay.

6. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively long intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a code following relay receiving energy from the rails of said section, a pair of decoding relays controlled by said code following relay in such manner that one but not the other decoding relay will release during each of said energy intervals of long duration, and that said other but not said one decoding relay will release during each of said long intervals of no energy, and traffic governing apparatus controlled by said decoding relays.

'7. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively long intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a code following locomotive relay receiving energy from the rails of said section, a first relay controlled over a front contact of said code following relay and capable of bridging said short but not said long intervals of no energy, a second relay controlled over a back contact of said code following relay and capable of bridging said short but not said long energy impulses, and a cab signal controlled by said first and second relays.

8. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively long intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a code following relay receiving energy from the rails of said section, a first relay controlled over a front contact of said code following relay and capable of bridging said short but not said long intervals of no energy, a second relay controlled over a back contact of said track relay and capable of bridging said short but not said long energy impulses, a third relay controlled over a front contact of said first relay and capable of bridging the code operation of said first relay, a fourth relay controlled over a front contact of said second relay and capable of bridging the code operation of said second relay, and traffic governing apparatus controlled by said third and fourth relays.

9. In combination, a section of railway track, means for supplying the rails of said section with coded current of one of a group of time codes selected in accordance with traific conditions in advance of said section, each of said time codes comprising a unit cycle which is repeated uniformly without cyclic variation and the unit code cycles in the individual time codes of said group being characterized by a difference in the relative as well as the absolute duration of the on and off intervals of said unit cycle, a code following relay receiving energy from the rails of said section and capable of following the on" and off intervals of said unit code cycles, a group of decoding relays controlled by said code following relay and timed for selective response in accordance with the time code being supplied to said section, at least one relay of said group being controlled over a circuit which includes a contact of said code following relay, and traffic governing apparatus controlled by said decoding relays.

10. In combination, a section of railway track, means for supplying the rails of said section with coded current of one of a group of time codes selected in accordance with traffic conditions in advance of said section, each of said time codes comprising a unit code cycle which is repeated uniformly without cyclic variation and the unit code cycles in the individual time codes being characterized by a difference in the relative as well as the absolute duration of the on interval with respect to the off interval of said unit cycle, a code following relay receiving energy from the rails of said section and capable of following the on and off intervals of said unit code cycles, a group of decoding relays controlled by said code following relay and timed for selective response in accordance with the time code being supplied to said section, at least one relay of said group being controlled over a circuit which includes a contact of said code following relay, and traffic governing apparatus controlled by said decoding relays.

11. In combination, a section of railway track, means for at times supplying the rails of said section with a first code comprising uniformly recurrent energy impulses separated by intervals of no energy and for at other times supplying the rails of said section with a second code also comprising uniformly recurrent energy impulses separated by intervals of no energy, said second code differing from said first code in the relative as well as the absolute duration of the on intervals with respect to the off intervals of the code, a code following relay receiving energy from the rails of said section and capable of following the on and off intervals of said first and second codes, a pair of decoding relays each of which is controlled over a circuit which includes a contact of said code following relay and which are timed for selective response to operation of said code following relay on said first or said second code respectively, and traffic governing apparatus controlled by said decoding relays.

12. In combination, a section of railway track, means for supplying the rails of said section with coded current of one of a group of time codes selected in accordance with traffic conditions in advance, each of said codes comprising uniformly recurrent on intervals of energy separated by off intervals of no energy and differing from one another according as said on intervals or said off intervals or both on and off intervals are of relatively long or of short duration, a code following relay receiving energy from the rails of said section and capable of following the on and off intervals of said codes, a first relay controlled over a front contact of said code following relay and having a release time sufiicient to bridge a short off code interval, a second relay controlled over a back contact of said code following relay as well as a front contact of said first relay and having a release time sufficient to bridge a short on code interval, a third relay controlled over a back contact of said code following relay as well as a front contact of said first relay and having a pickup time suflicient to prevent pickup on a short off code interval but insufficient to prevent pickup on a long off code interval, a fourth relay controlled over a front contact of said code following relay as well as a front contact of said second relay and having a pickup time sufficient to prevent pickup on a short on code interval but insufficient to prevent pickup on a long on code interval, and traffic governing apparatus controlled by said four relays.

13. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively short intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a code following relay receiving energy from the rails of said section and capable of following the on" and off intervals of said codes, a first relay controlled over a front contact of said code following relay and having a release time sufiicient to bridge a short off code interval, a second relay controlled over a back contact of said code following relay as well as a front contact of said first relay and having a release time suificient to bridge a short on code interval, a third relay controlled over a front contact of said code following relay as well as a front contact of said second relay and having a pickup time sufficient to prevent pickup on a short on code interval but insuflicient to prevent pickup on a long on code interval, and

traffic governing apparatus controlled by said three relays.

14. In combination, a section of railway track, means for at times supplying the rails of said section with code comprising energy impulses of relatively short duration separated by relatively short intervals of no energy and for at other times supplying the rails of said section with code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a code following relay receiving energy from the rails of said section and capable of following the on and off intervals of said codes, a first relay controlled over a back contact of said code following relay and having a release time sufiicient to bridge a short on code interval; a second and a third relay both controlled over a front contact of said code following relay as well as a front contact of said first relay, said second relay having a release time sufiicient to bridge a short on code interval and said third relay having a pick-up time sufiicient to prevent pickup on a short on code interval but insufficient to prevent pickup on a long on code interval; and trafiic governing means controlled by said second and third relays.

15. In combination, a section of railway track, means for at times supplying the rails of said section with coded current of a first code comprising a unit code cycle which is repeated uniformly without cyclic variation and for at other times supplying the rails of said section with coded current of a second code differing from said first code in the relative as well as the absolute duration of the intervals within the unit code cycle, a code following relay receiving energy from the rails of said section, and a decoder including a pair of windings respectively controlled over a pair of circuits one of which includes a front contact of said code following relay and the other of which includes a back contact of said code following relay, said decoder being selectively responsive according as said first or said second code is supplied to said section.

16. In combination, a section of railway track, means for at times supplying the rails of said section with coded current of a first code comprising a unit code cycle which is repeated uniformly without cyclic variation and for at other times supplying the rails of said section with coded current of a second code differing from said first code in the relative as well as the absolute duration of the intervals within the unit code cycle, a code following relay receiving energy from the rails of said section, and timing means including a pair of windings controlled respectively by energy supplied to a first circuit over a. front contact of said code following relay as well as by energy supplied to a second circuit over a back contact of said code following relay, said timing means being selectively responsive according as said first or said second code is supplied to said section.

17. In combination, a pair of conductors, means for at times supplying said conductors with coded current of a first code comprising current impulses which recur at uniform intervals and for at other times supplying said conductors with coded current of a second code comprising current impulses which also recur at uniform intervals but in which the ratio of the duration of an impulse to the duration of the interval between impulses diifers from that existing in said first code, a code following relay receiving energy from said conductors, and decoding apparatus including a pair of windings controlled respectively by energy supplied to a first circuit over a front contact of said code following relay as well as by energy supplied to a second circuit over a back contact of said code following relay, said decoding apparatus being selectively responsive according as said first or said second code is supplied to said pair of conductors.

18. In combination, a pair of conductors, means for at times supplying said conductors with coded current of a first code comprising current impulses which recur at uniform intervals and for at other times supplying said conductors with coded current of a second code comprising current impulses which also recur at uniform intervals but in which the ratio of the duration of an impulse to the duration of the interval between impulses diifers from that existing in said first code, a code responsive device receiving energy from said conductors, a pair of timing circuits one of which is efiective when said coding device is energized and the other of which is effective when said coding device is deenergized, and a decoder governed by said code responsive device and including a pair of windings governed respectively by means of said timing circuits, said decoder being selectively responsive according as said device is receiving current of said first or said second code.

19. In combination, a pair of conductors, means for at times supplying said conductors with a first code comprising energy impulses of relatively short duration separated by relatively long intervals of no energy and for at other times supplying said conductors with a second code comprising energy impulses of relatively long duration separated by relatively short intervals of no energy, a code responsive device receiving energy from said conductors, and decoding apparatus including a pair of windings respectively controlled over a pair of circuits one of which is effective when said code responsive device is energized and the other of which is effective when said code responsive device is deenergized, said decoding apparatus assuming one or another condition according as said device is receiving energy of said first or said second code.

CHARLES W. FAILOR.