US2141803A

US2141803A - Railway traffic controlling apparatus

Info

Publication number: US2141803A
Application number: US692155A
Authority: US
Inventors: Howard A Thompson
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1933-10-04
Filing date: 1933-10-04
Publication date: 1938-12-27
Anticipated expiration: 1955-12-27

Description

' HIS ATTORNEY INVENTOR [Iowa/WA Tizompson BY 9 Sheets-Sheet l H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Flled Oct 4, 1935 Dec. 27, 1938. H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Oct' 4, 1935 9 Sheets-Shee t 2 Howe/WA.

BY Qflnf nvvmvroze Thompson HIS ATTORNEY c. 27, 1938. H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS 9 Sheets-Sheet 3 Filed Oct.

..N 3 m wu INVENTOR ldA. Tho/22,050 (2 Q F N fiowa' B [176' ATTORNEY Dec. 27, 1938. H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed 001;. 4, 1933 9 Sheets-Sheet '4 INVENTOR P0 ardAJ/gom @211 By How HIS ATTORNEY mm&ma

- 938- H. A; THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS 9 Sheets-Sheet 5 Filed Oct. 4, 1933 mpsozz INVENTOR HawaMA Tho ATTORNEY HIS Dec. 27, 1938.

H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS F'ild- Oct.

4, 1953 9 Sheets-Sheet 5 J E Ni INVENTOR Thom 18012 Iowa/n24 I BY H16 A TTORNEY Dec. 27, 1938. H A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Oct. 4, 1955 9 Sheets-Sheet 7 m W m n ,Y m Wm o M m .35 ad w w De c.27, 1938. H. A. THOMPSON RAILWAY TRAFFIC CONTRQLLING APPARATUS 9 Sheets-Sheet Filed 001;. 4, 1935 wAHQ .N H N m wmw Q e i J 3% K WNN RQNU 3 up m Hm I w M A%m a W W H5 ,wmmmma Dec. 27, 1938. H. A. THOMPSON 2,141,803

RAILWAY TRAFFRIC CONTROLLING APPARATUS Filed Oct. 4, 1953 9 Sheets-Sheet 9 INVENTOR Howard/1.7720122 27301 2 BY 01W HIS ATTORNEY Patented Dec. 27, 1938 UNITED STATES REISSUED F'E'E FFIQE RAILWAY TRAFFIC CONTROLLING APPARATUS Application October 4,

4'7 Claims.

My invention relates to railway traffic controlling apparatus, and particularly to apparatus for controlling a plurality of trafiic governing devices such as switches and signals, or a plurality of other indicating devices, at one point, over a single pair of line wires by control apparatus at a second point.

My invention is particularly adapted for, although not limited to, the remote control and return indication of switches and signals, and the control of automatic signals each of which indicates traffic conditions four or more blocks in advance.

I will describe five forms of railway trafiic controlling apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figs. l and 1 when placed end to end with Fig. 1 on the left, constitute a diagrammatic view showing one form of apparatus embodying my invention for the control and indication of switches and signals. Figs. 2 2 and 2, when placed end to end in the order named, with Fig. 2 on the left, and Figs. 3 3 and 3, when placed end to end in the order named, with Fig. 3 on the left, constitute diagrammatic views showing two forms of apparatus for the control of five-block and four-block automatic signals, respectively, and also embodying my invention. Figs. 4 and 5 are views showing modifications of the apparatus shown in Figs. 3 3 and 3, and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Figs. 1 and l a railway track switch, designated by the reference character F, is shown connecting a main track Y with a siding Z. Signals, each of which is designated by the reference character S with a distinguishing exponent, govern traffic movements in opposite directions over switch F. Other traffic governing devices shown as electric lamps and designated by the reference character E with distinguishing exponents, are also shown adjacent switch F.

Main track Y and siding Z are divided by insulated joints 2 to form a track section ff-hh adjacent switch F. This section is provided with a track circuit including a battery 3 connected across the rails adjacent one end of the section and a relay T connected across the rails adjacent the opposite end of the section.

Switch F operates a contact piece 12 which occupies the position in which it is shown in the drawings when switch F is in its normal position, and which occupies a position designated by the 1933, Serial No. 692,155

reference character 12 when switch F is moved to the reverse position. A pole-changer designated by the reference number I28 is also operated in conjunction with switch F.

Each of the signals S is controlled by a stick relay designated by the reference character H with an exponent corresponding to that of the signal which it controls. Stick circuits for relays H H H and H for controlling signals S are controlled by switch contact piece 12 and by track relay T as well as by a relay designated by the reference character J Switch F is controlled by two stick relays designated by the reference characters A and A respectively. Relay A governs operations of switch F to its normal position, and relay A governs operations of switch F to its reverse position.

Lamps E, relay J and the pick-up circuits for relays A and H are selectively controlled by slow releasing relays designated by the reference characters L L and L respectively, and by relays designated by the reference characters R and R respectively.

Relay L receives energy from the secondary winding 29 of a transformer N through a rectifier D which may be of a type which comprises four copper oxide asymmetric units each of which is designated by the reference numeral 4. Relays L and L are controlled by a neutral code following relay U and by a polarized code following relay P Relay P is so constructed that, during periods when it is deenergized, it will retain its polar contacts closed in the position to which they were last previously operated. Relays R and R receive energy from rectifiers D and D respectively, which may be of the same type as rectifier D Rectifiers D and D are selectively energized by current from a second transformer N flowing through tuned circuits which, as here indicated, comprise condensers designated by the reference characters a and a respectively, and reactors designated by the reference characters b and 27 respectively, which are so proportioned that the circuit for rectifier D is responsive only to alternating current having a frequency of 80 cycles per minute to operate relay R and the circuit for rectifier D is responsive only to alternating current having a frequency of 120 cycles per minute to operate relay R Transformer N is provided with a tap at the mid point of its primary winding 1, which is connected to negative terminal 0 of a source of current not shown in the drawings. The ends of primary winding 1 of transformer N are at times alternately connected to positive terminal B of the same source of current through front and back points of a contact 5 of relay U In this way, current is -alternately supplied in opposite directions to thetwo halves of primary winding '1 of transformer N causing alternating current to be generated in the secondary winding 8 of transformer N of a frequency corresponding to the frequency of closing the front point of contact 5 of relay U Relays U and P are connected across line wires I2 and I5 in multiple with each other and in multiple with-a condenser a but in series with the primary winding I3 of transformer N and with a back contact I4 of a slow releasing relay I. Current for energizing relays U and P and primary winding I3 of transformer N is carried by conductors I2 and I5 from a control point which may be a dispatchers office or an interlocking tower.

At the control point, a master circuit controller M which, as here shown, is of the push button type biased to a normal position, but which may be of any other suitable type, is equipped with a front contact 24 which is closed only when the circuit controller is in its normal position, and with a back contact 25 which is closed only when the circuit controller is operated to a depressed position.

Current is supplied to a line control relay K through back contact 25 of circuit controller M. A resistance unit 26 is included in the pick-up circuit for relay K in order to make this relay slow in picking up.

When front contact I6 of relay K has become closed, control currents of various characteristics can be supplied over conductors I2 and I5 as selected by independent auxiliary manually operable circuit controller contacts which are designated by the reference character m with distinguishing exponents, and which, as here shown, are of the push button type, but which may be of any other suitable type such, for example, as lever operated contacts.

The control currents thus supplied to conductors I2 and I5 through contacts 112 to m inclusive, are generated by one or the other or both of the groups q and q of cells of a battery Q When any one of the contacts m to m inclusive, is closed while contact I6 of relay K is closed, conductors I2 and I5 are supplied with alternating current from secondary winding ll of a transformer N as well as with current from battery Q The character of the control currents supplied by battery Q and by transformer N may be modified by coding devices in the dispatchers oilice designated by the reference characters C 0 C and C Each of these coding devices may be of an oscillatory type operating at a low frequency of the order of 40, 60, or cycles per minute, and provided with a self control contact II as well as with other contacts for modifying the currents supplied to line wires I2 and I5, and also having a winding designated by the numeral corresponding to the frequency at which the coder operates. The contacts of each coder C are biased by a coil spring I0 to the position shown in the drawings, when the coder is deenergized.

Vfhen either contact m or m is closed, continuous control current of what I will term positive polarity is supplied to conductors I2 and I5 by battery Q When either contact m or m is closed, continuous control current of negative polarity is supplied to conductors. I2 and I5 by battery Q When contact m or contact m is closed, unidirectional current of positive polarity, periodically interrupted by coder C at a frequency of eighty times per minute, is supplied to conductors I2 and I5 by battery Q When contact m or contact m is closed, unidirectional current of positive polarity, periodically interrupted by coder C at a frequency of 120 times per minute, is supplied to conductors I2 and I5 by battery Q When contact m or contact m is closed, unidirectional current of negative polarity, periodically interrupted at a frequency of eighty times per minute, is supplied to conductors I2 and I5. When either contact m or m is closed, unidirectional current of negative polarity, periodically interrupted at a frequency of 120 times per minute, is supplied to conductors I2 and I5. When either contact m or m is closed, positive current, periodically interrupted at a frequency of forty times per minute, is supplied to conductors I2 and I5 alternately with negative current periodically interrupted at a frequency of forty times per minute. When contact m or contact m is closed, current of positive polarity, periodically interrupted at a frequency of sixty times per minute, is supplied to conductors I2 and I5 alternately with current of negative polarity interrupted at a frequency of sixty times per minute.

The character of the current supplied to conductors I2 and I5 by battery Q through each contact m is designated on the drawings directly to the right of the showing of each contact m. For example, continuous current of positive polarity supplied through contacts m and m is designated by the plus sign; continuous current of negative polarity supplied through contacts m and m is designated by the minus sign; current of positive polarity periodically interrupted at a frequency of eighty times per minute, supplied through contacts m and m is designated +80; and current of positive polarity interrupted forty times per minute and alternated with current of negative polarity interrupted forty times per minute, supplied through contacts m and 111 is designated :40.

Whenever current is supplied to conductors I2 and I5 from battery Q by the closure of any one of the contacts m, both relays U and P will be energized, and hence one or the other or both of the relays L and L will be energized accordingly as current of positive, or of negative polarity, or of positive polarity periodically alternated with current of negative polarity is supplied to conductors I2 and I5 by battery Q Whenever transformer N supplies alternating current to conductors I2 and I5, such current will energize transformer N which will, in turn, energize relay L At the control point, the condition of track relay T, switchF and signals S is shown by a plurality of indicators, here shown as electric lamps, each of which is designated by the reference character c with an exponent which is indicative of the traffic governing device with which it is associated. Indicators e are selectively controlled by relays L L L R and R similarly to the manner in which relays A, H and J and lamps E are controlled by relays L L L R and R as previously described. As shown in the drawings, relays L L L R and R, are controlled only by track relay T, switch F, and signals S for in turn controlling associated indicators designated by the reference character 6 with distinguishing I! exponents. Relays L L L R and R could also be controlled by other traffic governing devices, not shown, for in turn controlling other indicators and circuits which are shown in dash lines, and without reference characters, adjacent indicators 6.

Relay L receives energy from transformer N through rectifier D similarly to the manner in which relay L receives energy from transformer N through rectifier D Relays R and R receive energy from transformer N through rectifiers D and D similarly to the manner in which relays R and R receive energy from transformer N through rectifiers D and D Relays L and L are controlled by code following relays U and 1 similarly to the manner in which relays L and L are controlled by code following relays U and P Relay P is constructed similarly to relay P for retaining its polar contacts closed when its windings are deenergized.

Code following relays U and l? are connected across line conductors I2 and I5 in multiple with each other and with a condenser a but in series with primary winding I3 of transformer N and also in series with back contact 28 of relay K and with front contact 24 of master controller M. Similarly to the manner in which relays U and P and primary winding I3 of transformer N are selectively controlled by currents from battery Q and transformer N relays U and P and primary winding I3 of transformer N are selectively controlled by currents supplied to conductors I2 and I5 from a battery Q and from a transformer N adjacent switch F.

The various currents supplied to conductors I2 and I5 by battery Q are selectively controlled by contacts operated by signals S and by contact 9&- of relay T and contact 95 of a switch indication relay 1. Relay is controlled by pole-changer I28, which is operated in conjunction with switch so that contact 55 is closed in its normal position, in which it is shown in the drawings, when switch F is in its normal position, and so that contact 95 is closed in its reverse position when switch F is in its reverse position.

The current supplied to conductors I 2 and I5 by battery Q selectively controlled by signals 8 and S in their proceed positions is periodically interrupted by coders C and C respectively. which operate at low frequencies of the order. of 80 and 120 cycles per minute, similarly to coders C and C and the current suppliedv by battery Q selectively controlled by signals S and S in their proceed positions, is periodically alternated by coders C and C which operate at half the frequencies of coders C and C respectively, that is, forty and sixty cycles per minute. When both signals S and S are in their stop positions while switch F is in its reverse position, battery Q will supply constant unidirectional current of negative polarity to conductors I2 and I5. When signals S and S are in their stop positions while switch F is in its normal position, battery Q will supply constant unidirectional current of positive polarity to conductors I2 and I5. In addition to the current supplied to conductors I2 and I5 by battery Q alternating current will be supplied to When the dispatcher closes any one of the pushv button contacts m and contact 25 of master controller M, causing one of the relays L and L to become energized, a slow releasing relay G will become energized by a circuit which includes a front contact of one or the other of the relays L and L When the dispatcher releases master controller M after having depressed it to supply curr nt to conductors I2 and I5, relay K will become deenergized because its pick-up and stick circuits will then be opened at contact 25 of controller M. With relay K deenergized and with controller M in its normal position, the indication apparatus in the dispatchers office will be in condition to be controlled by track relay T, switch F and signals S. An indication current will then be supplied to conductors I2 and I5, and such current will fiow to these conductors through the winding of a slow release indication stick relay I in series with two of the units 4 of a rectifier D and with contact I8 oi relay G and contacts l9- and 8i of relays L and L respectively. Relay I, upon becoming energized. will disconnect, at its back contact I4, relays U and P and transformer N from conductors I2 and I5, thus preventing indication current from causing any of the control relays L L L R and R to become energized.

Having described, in general, the arrangement and operation of the form of apparatus shown in Figs. 1 and l I will now trace in detail a few examples of the operation of this form of apparatus.

As shown in the drawings, each of the auxiliary push button circuit controller contacts m is in its normally open position; master push button controller M is in its normal position; each of the signals S is in its stop position; switch F is in its normal position; each of the trafiic governing devices E is deenergized; track relay T is energized; each of the control relays K, U P L L L R R A H and J is deenergized; switch control relay A is energized by its stick circuit; each of the indicators e is deenergized except indicator e which is energized; each of the indicator control relays I, U P and L is energized; and each of the indicator control relays G, L L R and R is deenergized.

The stick circuit by which relay A is energized passes from terminal B, through contact 66 of relay A contact 6? of relay A and the winding of relay A to terminal 0.

The circuit by which relays I and U and P are energized is a stick circuit for relay I, passing from portion q of battery Q through conductor I2, windings of relays U and P in multiple, winding I3 of transformer N contact 28 of relay K, contact 2 5 of circuit controller M, conductor I5,-upper left-hand unit 4 of rectifier D winding of relay I, contact 82 of relay I, lower right-hand unit 4 of rectifier 13', wire 83, front point of contact 94 of relay T, contact of relay 1 in its left-hand position, contact 84 of signal S and contact 86 of signal S back to portion q of battery Q The current supplied to this circuit by battery Q is of positive polarity, and therefore contact 6 of relay P is closed in its left-hand position. The current supplied to this circuit is continuous, and so causes contact 5 of relay U to be constantly closed at its front point.

Relay L is therefore energized by a circuit passing from terminal B, through the front point of contact 5 of relay U contact Ii of relay P in its left-hand position, and the winding of relay L to terminal 0.

With relay L energized, indicator e is lighted by its circuit passing from terminal B, through the back point of contact 16 of relay L back point of contact I01 of relay R back point of contact I08 of relay R front point of contact I09 of relay L and indicator e to terminal 0.

Primary winding 9 of control transformer N and primary winding 9 of indication transformer N are constantly connected with terminals BX and CX of a suitable source of current not shown in the drawings, and are therefore normally energized. Each of the control coders C C C and C and also each of the indication coders C C and C is connected through its own contact II with terminals B and O of a second source of current not shown in the drawings, and is, therefore, constantly in operation.

I will assume that the dispatcher desires to permit a train to move along track Y from left to right as shown in the drawings, which I will assume to be the eastbound direction, over switch F in its normal position. He will, therefore, close contact m and depress master controller M. This operation of controller M will open its contact 24, thereby breaking the circuit previously traced for relays I, U and P With relay U" deenergized, the circuit traced for relay L will be open at the front point of contact 5 of relay U causing relay L to be deenergized. The circuit previously traced for indicator e will therefore be broken at the front point of contact 509 of relay L causing this indicator to be deenergized. Relay I, having a slow release, will not at once close its back contact [4, but will do so after the lapse of a brief period of time.

The closing of contact 25 of master controller M will cause slow pick-up relay K to become energized by its pick-up circuit passing from terminal B, through contact 25 of controller M, re-

sistor 26, and the winding of relay K to terminal 0. Relay K, upon closing its contact 21, will complete its own stick circuit passing from terminal B, through contact 25 of controller M, contact 2'! of relay K, and the winding of relay K to terminal 0.

Relay K, upon becoming energized, will also complete, at its contact I6, a circuit passing from the positive terminal of the portion q of battery Q through conductors l2 and H windings of relays U and P in multiple with each other and with condenser a primary winding I 3 of transformer N contact M of relay I, conductors l5 and I5 contact I6 of relay K, secondary winding ll of transformer N contact m and contact 18 of coder C back to battery Q Alternating current is supplied to this circuit by transformer N and current of positive polarity periodically interrupted at a frequency of eighty times per minute is supplied tothe same circuit by battery Q The alternating current will flow through condenser a to energize primary winding l3 of transformer N and the current from battery Q will flow through the windings of relays U and P Secondary winding 29 of transformer N will, therefore, supply alternating current to rectifier D which will, in turn, supply direct current for operating relay L The current of positive polarity from battery Q periodically interrupted eighty times per minute, will cause relay P to hold its contact 6 closed in the left-hand position and will cause relay U to close contact 5 alternately at its front and back points eighty times per minute.

During the periods when contact 5 of relay U is closed at its front point, a circuit will be completed for energizing relay L passing from terminal B, through contact 5 closed at its front point, contact 6 of relay P in its left-hand position, and the winding of relay L to terminal 0.

Relay L upon becoming energized, completes, at its contact 16, a circuit for energizing relay G, passing from terminal B, through contact I6, contact I1 of relay I, and the winding of relay G to terminal 0.

Each time that contact 5 becomes closed at its front point, a circuit is also completed for energizing the right-half of primary winding I of transformer N passing from terminal B, throughthe front point of contact 5, and right-half of winding 1 to terminal 0. Each time that contact 5 is closed at its back point, a circuit is completed for energizing the left-half of primary winding I in the opposite direction, passing from terminal B, through the back point of contact 5, and the left-half of winding I to terminal 0. Alternating current is therefore generated in secondary winding 8 of transformer W of a fre quency to which the circuit for rectifier D is tuned, and hence rectifier D will supply direct current for operating relay R Relays L and L being slow releasing, will retain their front contacts in the closed position in the intervals during which they are deenergized by the opening of contact I8 of coder C With relays L R and L energized, a circuit will be completed for energizing relay H passing from terminal B, through the front point of contact 30 of relay L front point of contact 42 of relay R front point of contact 45 of relay L back point of contact 41 of relay L winding of relay H contact I2 of switch F in its normal position, and contact 96 of relay T to terminal 0. Relay H jupon closing its front contacts, completes its own stick circuit passing from terminal B, through contact 52 of relay J contact 56 of relay H winding of relay H contact 72 of switch F, and contact 96 of relay T to terminal 0.

At the same time, relay H completes a circuit for signal S passing from terminal B, through contact 51 of relay H and the mecha nism of signal S to terminal 0. The arm of signal S thereupon moves to its proceed position, closing its contact 84 in the corresponding position.

When the dispatcher now releases master controller M, relay K will become denergized on account of the opening of contact 25 of controller M. Contact I 6 of relay K will therefore open the line control circuit previously traced for signal S causing relays L R and L to become deenergized. The arm of signal S will, however, be retained in its proceed position on account of relay H being energized by its stick circuit.

Relay G, being slow releasing, retains its contact 18 in the closed position for a brief period after its circuit becomes opened at contact 16 of relay L Therefore, when back contact 28 of relay K closes, an indication circuit will be completed, passing from the positive terminal of the portion 1;! of battery Q through the back point of contact I05 of coder C contact 84 of signal S contact 95 of relay in its left-hand position, front point of contact 94 of relay T, wire 83, upper right-hand unit 4 of rectifier D", winding of relay I, contact I8 of slow release relay G, contact 19 of relay L contact 8! of relay L lower left-hand unit 4 of rectifier D wire l5, contact 24 of controller M, contact 28 of relay K, primary winding I3 of transformer N the windings of relays U and P in multiple with each other and with condenser c and conductor l2 back to the portion q of battery Q Relay I, upon becoming thus energized, completes, at its contact 82, its own stick circuit which is the same as the pick-up circuit just traced except that contact 82 completes a branch path around the part of the pick-up circuit which includes contact 18 of relay G, contact 19 of relay L and contact 8| of relay L Coder C is constantly operating, and hence its contact m5 is alternately closing at its front and back points. When contact H15 of coder C closes at its front point, the circuit just traced will be provided with a branch path which includes the front point of contact I05 and the portion q of battery Q instead of the back point of contact H15 and the portion q of battery Q Primary winding l3 of transformer N and the windings of relays U and P are therefore periodically energized by current of negative polarity from the portion q of battery Q alternately with current of positive polarity from the portion q of battery Q The current generated in secondary winding 29 of transformer N as a result of this periodically alternated current will, however, not be sufficient to operate relay L Relay U will close its contact 5 at the front point each time current of positive polarity is supplied to conductors l2 and 15 by portion q of battery Q and also each time current of negative polarity is supplied to conductors i2 and I5 by the portion q of battery Q Contact 5 will close at its back point each time contact [-05 of coder C opens at either its front or its back point. Contact 6 of relay P will close in its left-hand position each time current of positive polarity is supplied to conductors l2 and 15 by portion q of battery Q and will close in its right-hand position each time current of negative polarity is supplied to conductors l2 and [5 by portion q of battery Q Since contact 5 of relay U closes at its front point for each positive and negative pulse, it will thus close 120 times per minute, and hence relay R the circuit for rectifier D being tuned to 120 cycles per minute, will become energized.

Each time the current of positive polarity is supplied to relays U and P relay L will become energized by its circuit previously traced. Since relay L is slow releasing, it will retain its contacts closed at the front points during the periods between the periodic closings of its circuit just traced.

Each time relays U and P become energized by current of negative polarity, relay L will be energized by a circuit passing from terminal B, through the front point of contact 5 of relay U contact 6 of relay P in its right-hand position, and the winding of relay L to terminal 0. Relay L being also slow releasing, will retain its contacts closed at their front points during the intervals between the successive closings of its circuit just traced.

With relay R energized, and with relays L and L retaining their contacts closed at the front points on account of being periodically energized by their circuits just traced through contact 6 of relay P in its left-hand and right-hand positions, a circuit will be completed for energizing indicator c passing from terminal B, through the back point of contact Hit of relay L back point of contact ID! of relay R front point of contact I58 of relay R front point of contact lid of relay L front point of contact H5 of relay L and indicator e to terminal 0. Lamp e will therefore be lighted, and hence the dispatcher will know that signal S is indicating proceed.

I will assume that while signal S is indicating proceed and indicator e is lighted to show the dispatcher that signal S is indicating proceed, an east-bound train passes signal S causing track relay T to become deenergized. Relay T, upon becoming deenergized, opens its contact Q6, thereby breaking the stick circuit previously traced for relay H Relay H upon becoming deenergized, opens its contact 51, thereby breaking the mechanism circuit for signal S and thus causing signal S to indicate stop. The deenergization of relay T also causes its contact 94 toopen at the front point, thereby breaking the control circuit previously traced for indication relays I, U and P and so causing indicator lamp e to be extinguished.

Upon the closing of contact 94 of relay T at its back point, a third circuit will be completed for indication relays I, U" and P passing from the portion q of battery Q through contact I02 of coder C back point of contact 94 of relay T, wire 83, and thence by the path previously traced for the stick circuit for relay I, through the windings of relays I, U and P back to battery Q It will be noted that the windings of relays I, U and P are deenergized for only the brief period between the opening of contact 94 of relay T at its front point and the closing of this contact at its back point, and hence relay I does not have time to release its front contacts. The transfer Will therefore be made directly from the stick circuit for relay I for indicating the clearing of signal S to the stick circuit for relay I for indicating the occupancy of track relay T, without it being necessary to energize relay I by a pickup circuit.

By means of this circuit, relays U and P are energized by current of negative polarity periodically interrupted at a frequency of 80 times per minute. Relay U will, therefore, close its contact 5 at its front and back points, alternately, 80 times per minute, and relay P will close its contact 6 in the right-hand position. With contact '5 of relay U closing at its front and back points, alternately, 80 times per minute, transformer N will supply current for which the circuit for rectifier D is tuned, causing relay R to become energized. The circuit previously traced for relay L will be completed through the front point of contact 5 of relay U and contact 5 of relay P in its right-hand position, causing relay L to be energized.

With relays R and L energized, a circuit will be completed for energizing indicator 6 passing from terminal B, through the back point of contact I05 of relay L front point of contact ll]? of relay R back point of contact HI of relay L contact H3 of relay L and indicator e to terminal 0. With indicator e lighted, the dispatcher will know that track section ff-hh is occupied.

When the train leaves section ffhh, relay T again becomes energized, but signal S will not clear without further action by the dispatcher. Relay T, upon becoming energized, opens its contact 94 at the back point and closes this contact at the front point, thereby transferring relay I from the stick circuit last described to the stick circuit first traced for this relay. This will cause lamp e to be extinguished and lamp e to again be lighted by its circuit previously traced.

I will now assume that the dispatcher desires to operate traffic governing device E He will therefore close contact m and will again depress master controller M. This operation of controller M will open, at its contact 24, the circuit traced for indication relays U and P and will close, at its contact 25, the pick-up circuit previously traced for relay K. Upon the lapse of a sufficient period of time after the opening of contact 24 of controller M and before relay K has had time to pick up, slow release relay I will open its front contact 82- and will close its back contacts l4 and 11. Contact l6 of relay K will then, upon becoming closed, complete a circuit for transformer N and relays U and P passing from portion q of battery Q thence by the path previously traced for transformer N and relays U and P as far as contact I 6 of relay K, and thence through contact 111. backto portion q of battery Q Over this circuit, relays U and P will be energized by continuous current of positive polarity from the portion q of battery Q Transformer N will not respond to such current to energize relay L but relay U will close its contact 5 at the front point and retain its contact in this position, and relay P will close its contact 6 in the left-hand position and retain its contact 6 in this position.

Relay L will therefore be constantly energized by its circuit previously traced, and hence a circuit will be completed for energizing trafiic governing device E passing from terminal B, through the back point of contact 30 of relay L back point of contact 3| of relay R back point of contact 32 of relay R front point of contact 33 of relay L and traffic governing device E to terminal 0.

I will next assume that the dispatcher desires to energize traific governing device E Hewill therefore close contact m and depress controller M, causing a circuit to be completed for transformer N and relays U and P which is similar to the circuits previously traced for transformer N and relays U and P except that it is supplied with current by a path passing from portion q of battery Q through contact 2| of coder C contact m, and secondary winding ll of transformer N Since this path includes contact 2| of coder C the current supplied by battery Q to relays U and P will be periodically interrupted at a frequency of 120 times per minute, and will be a negative polarity. The alternating current supplied to the circuit by transformer N will cause relay L to become energized. The direct current of negative polarity periodically interrupted 120 times per minute will cause transformer N to generate current of a frequency to which the circuit for rectifier D is tuned, and relay R will therefore now be energized. Since the direct current is of negative polarity, relay L will be energized on account of contact 6 of relay P being closed in its right-hand position.

With relays U, R and L energized, a circuit will be completed for energizing device E passing from terminal B, through the front point of contact 30 of relay L back point of contact 42 of relay R front point of contact 43 of relay R back point of contact 49 of relay L contact 5| of relay L and device E to terminal 0.

I will now assume that the dispatcher desires to operate switch F to its reverse position. He Will, therefore, close contact'm and will again depress circuit controller M. Upon the lapse of a brief period of time after the opening of contact 24 of controller M, relay I will permit its contact 82 to open and its contacts l4 and TI to close.

On account of the closing of contact 25 of controller M, relay K will become energized by its circuit previously traced, and will, upon the lapse of a given period of time, again close its contact l6, thereby completing a circuit for energizing relays U and P and primary winding I3 of transformer N passing from the portion q of battery Q thence by the path previously traced as far as contact 16 of relay K, secondary winding ll of transformer N contact 121. and back point of contact 22 of coder C back to battery Q It will be noted that contact 22 of coder C closes at its front point, alternately with its back point, 40 times per minute, and hence current is supplied to the circuit just traced by the portion q of battery Q through the front point of contact 22 of coder C alternately with portion q of battery Q through the back point of contact 22 of coder C Alternating current supplied to the circuit by transformer N will cause transformer N to supply alternating current to rectifier D for en-- ergizing relay L Relay U will be energized 40 times per minute by current passing from portion q of battery Q and 40 times per minute by current from the portion q of battery Q making a total of times per minute that relay U will close its contact 5 at the front point. Transformer N will, therefore, supply current to which the circuit for rectifier D is tuned, and hence relay R will be energized. Relay P on account of being energized alternately by current of normal and reverse polarities, will alternately close its contact 6 in the left-hand and the right-hand positions, causing relays L and L to be alternately energized through contact 6 in its left and right-hand positions, respectively. Relays L and L being slow in releasing, will retain their front contacts closed during the intervals between successive periods of energization.

With relays L R L and L holding their contacts closed at the front points, a circuit is completed for energizing relay A passing from terminal B, through the front point of contact 30 of relay L front point of contact 42 of relay R front point of contact 46 of relay L front point of contact 41 of relay L contact 64 of relay H contact 65 of relay H, and the winding of relay A to terminal 0. Relay A upon becoming energized, opens its back contact 66, thereby breaking the stick circuit previously traced for relay A and thus causing relay A to become deenergized. Relay A upon becoming deenergized, completes at its back contact 68 a stick circuit for A passing from terminal B, through contact 68, contact 69 of relay A and the winding of relay A to terminal 0.

The circuit for operating mechanism w of switch F to the normal position will now be open at contact '10 of relay A and the reverse energizing circuit for mechanism to will be closed, passing from terminal B, through contact ll of relay A and mechanism w to terminal 0.

' Mechanism w will therefore move switch F to its reverse position. Pole-changer I28 will thereby be reversed, causing relay f to be energized by current of reverse polarity. Contact of relay f 'will therefore now close in the right-hand position.

Due to the energization of relays L and L while relay I has been deenergized, relay G has been energized by a circuit passing from terminal B, including contact 15 of relay L in multiple with contact 16 of relay L contact ll of relay I, and the winding of relay G to terminal 0. When the dispatcher releases circuit controller M, thereby permitting relay K to become deenergized and open, at its contact iii, the circuit previously traced for relays U and P the consequent d'eenergization of relays U and P will cause relays L and L to become d-eenergized and hence, with relay f energized in the reverse direction, a switch indication circuit will be completed, passing from portion q of battery Q through contact 81 of signal S in its stop position, secondary winding ll of transformer N contact of signal S in its stop position, contact of relay 1 closed in its right-hand position, front point of contact 94 of relay T, wire 83, upper right-hand unit 4 of rectifier D winding of relay I, contact 18 of relay G, contact iii of relay L contact Bl of relay L lower left-hand unit 4 of rectifier D", conductor i5, contact 24 of circuit controller M, contact 28 of relay K, primary winding E3 of transformer N windings of relay U and P in multiple with each other and with condenser :1 and conductor l2 back to battery Q It will be noted that the circuit just traced is supplied with constant direct current by battery Q and with alternating current by transformer N Transformer N will, therefore, supply current to rectifier D for energizing relay L Relays U and l? are now constantly energized by current of reverse polarity, and hence relay L is energized by its circuit passing from terminal B, through front point of contact 5 of relay U contact 6 of relay 1? in its right-hand position, and the winding of relay L to terminal 0.

With relays L and L energized, a circuit is completed for energizing indicator e passing from terminal B, through the front point of contact lilt of relay L back point of contact Ill of relay R back point of contact H8 of relay R back point of contact lid of relay L contact l2l of relay L and indicator c to terminal 0. With indicator e lighted, the dispatcher will be informed that switch F occupies its reverse position.

I will next assume that the dispatcher desires to return switch F to its normal position. He will therefore close contact m and will again depress controller M. The circuit for transformer N and relays U and P will now be supplied with current of positive polarity from portion q of battery Q periodically interrupted 40 times per minute, and alternated with current of negative polarity from portion q of battery Q periodically interrupted 40 times per minute. The path by which the current of positive polarity is supplied to this circuit includes portion q of battery Q and the back point of contact 22 of coder 0 as well as contact m The path by which current of negative polarity is supplied to this circuit includes portion (1 of battery Q and the front point of contact 22 of coder C as well as contact m Secondary winding ll of transformer N is not included in either one of these paths, and hence no alternating current is now supplied to the circuit by transformer N Relay L will therefore remain deenergized.

The current of positive polarity alternated with the current of negative polarity at the frequency of 40 cycles per minute will cause contact 5 of relay U to close, at its front point, 80 times per minute, and also to close, at its back point, 80 times per minute. This will cause current to be generated by secondary 8 of transformer N of a frequency to which the circuit for rectifier D is tuned, and hence relay R will become energized. Relays L and L will be energized by their circuits through the front point of contact 5 of relay U and contact 6 of relay P in its normal and reverse positions, respectively.

With relays R L and L energized, a pick-up circuit will be completed for relay A passing from terminal B, through the back point of contact 3B of relay L front point of contact 3| of relay R front point of contact 35 of relay L front point of control 36 of relay L contact 62 of relay H contact 63 of relay H", and the winding of relay A to terminal 0. Relay A upon becoming energized, opens its back contact 68, thereby breaking the stick circuit previously traced for relay A and hence causing relay A to become deenergized. Relay A upon becoming deenergized, permits its back contact 66 to complete the stick circuit previously traced for relay A.

With relay A now energized, mechanism w' will be energized by its circuit passing from terminal B, through contact 10 of relay A and mechanism 11; to terminal 0. Switch F will therefore now be returned to its normal position. With switch F in its normal position, polechanger i283 will be returned to its normal position, causing relay f to again close its contact 95 in the left-hand position.

When the dispatcher now releases circuit controller M, a pick-up circuit will be completed for energizing relays I, U and P which is the same as the stick circuit first traced for relay I except that it includes contact 18 of relay G and contacts l9 and 8! of relays L and L respectively, instead of contact 82 of relay I. Relay I, upon becoming energized, completes, at its contact 82, the stick circuit first traced for this relay. Relays U and P will now be energized for causing indicator to become lighted as previously described.

When the dispatcher desires to return any of the signals S from the proceed position to the stop position, he can do so by closing contact m and operating the circuit controller M. This will cause a circuit to be completed for energizing relays U and P passing from the portion 1 of battery Q to conductor 12, thence by the path previously traced through the windings of relays U and P and primary winding i3 of transformer N as far as contact i6 of relay K, and then through contact m and contact H! of coder C back to battery Q Over this circuit, relays U and P are energized by direct current, of positive polarity, periodically interrupted times per minute. Relay U will therefore close its contact 5 at its front and back points alternately 120 times per minute, causing relay R to become energized. Since the circuit is supplied with current of positive polarity,'relay P will close its contact 6 in the left-hand position, causing relay L to become energized.

With relays R and L energized, a circuit will be completed for energizing relay J passing from terminal B, through the back point of contact 38 of relay L back point of contact SI of relay R front point of contact 32 of relay R front point of contact 38 of relay L back point of contact 59 of relay L and the winding of relay J to terminal 0. Relay J upon becoming energized, will open its contact 52, thereby breaking the stick circuit for any of the signal control relays H H", H and H controlling a signal which the dispatcher desires to return to the stop position.

Referring now to Figs, 2 2 and 2, reference characters I and I designate the rails of a railway traok over which traffic normally moves in the direction indicated by the arrow, which I will assume to be the eastbound direction. Rails I and l are divided by insulated joints 2 into blocks AA-BB, BBCC, CCDD, DD-EE, and EE-FF. Each of these blocks is further divided by other insulated joints 2 into two sections.

Block AA-BB, for example, is divided into sections AAaa and (ZlZ-BB. Each track section is provided with a track circuit comprising a battery 3 connected across the rails adjacent one end of the section, and a relay, designated by the reference character T with a distinguishing exponent, connected across the rails adjacent the opposite end of the section.

Adjacent the entrance end of each of the blocks shown complete, and also adjacent the entrance end of the block to the right of point FF, shown in part in Fig. 2, a signal is located for governing eastbound traffic movements. Each of these signals is designated by the reference character S with a distinguishing exponent according to its location. It is here assumed that each of the signals S is of the color light type comprising an upper group of lamps designated by the reference character a, and a lower groupof lamps designated by the reference character d. Each of these groups comprises a green or proceed lamp 9, a yellow or caution lamp 1 and a red or stop lamp T. It is to be understood, however, that my invention is not limited to signals of this particular type.

The lighting of the lamps of each signal S is controlled by three slow release relays designated by the reference character L with distinguishing exponents each of which includes the reference character of the associated signal. One of the relays L for each signal S is, in turn, controlled by the back point of a contact 5 of a neutral code following relay designated by the reference character U with a distinguishing exponent corresponding to that of the signal with which it is associated. The other two relays L for each signal S are controlled by the front point of contact 5 of the associated relay U, and by a polar contact 6 of a polarized code following relay P closed in its normal and reverse positions, respectively. Each relay P is distinguished by an exponent corresponding to that of the associated signal.

The relay U and the relay P for each signal are energized in multiple over a line circuit which is controlled by track relays for the sections of the associated block, and by the relays L for the next signal in advance, and also by a coding device .designated by the reference character C with a distinguishing exponent corresponding to that of the next signal in advance. The coding devices C are similar to the coders C shown in Figs. 1 and 1 and operate at a low frequency of the order of cycles per minute.

As shown in Fig.2, the track section immediately to the right of signal S is occupied by a train W which is represented by an axle and pair of wheels. The indications, and the meanings of the indications displayed by each of the signals S shown in the drawings, when train W is located as shown, in the section immediately to the right of point FF, are given in the following table.

Indication displayed Signal Meaning of indication Group 1/. Group d sr Red Red First block ahead of signal s is occupied. SE Yellow Red First block ahead is clear, but second block ahead is occupied. SD Yellow Ycllow First two blocks ahead are clear,

but third block ahead is occupied. SC Green Red First three blocks ahead are clear,

butiiourth block ahead is occupie SB..-" Green... Yellow First four blocks ahead are clear,

butd fifth block ahead is occupie SA Green Green First five blocks ahead are clear.

I will now describe the manner in which these indications are displayed under the conditions shown in the drawings. With train W occupying the section immediately ahead of signal S track relay T is deenergized, and hence the line circuit for relays U and P is open, causing these relays to be deenergized. Relays L and L are therefore also deenergized. Relay L however, is energized by a circuit passing from terminal B, through back point of contact 5 of relay U and the winding of relay L to terminal 0.

Lamp r of group u of signal S is therefore lighted by its circuit passing from terminal B, through the back point of contact I6I of relay L back point of contact I62 of relay L, and lamp r to terminal 0. Lamp r of group d of the same signal is lighted by a. circuit passing from terminal B, through the back point of contact I63 of relay L back point of contact I65 of relay L, and lamp r to terminal 0.

A circuit is completed for energizing relays U and P for signal S by continuous current of negative polarity, passing from portion Q of battery Q through contact I54 of relay L back point of contact I55 of relay L back point of contact I58 of relay L contact I59 of relay T contact I60 of relay T and the winding of relays U and P in multiple, back to battery Q With relays U and P energized by continuous current of negative polarity, contact 5 of relay U will be continuously closed at its front point, and contact 6 of relay P will be closed in the right-hand position. With contact 5 of relay U open at its back point, relay L is deenergized. With contact 5 of relay U closed at its front point, and with contact 6 of relay P closed in the righthand position, a circuit is completed for energizing relay L passing from terminal B, through the front point of contact 5 of relay U contact 6 of relay P in the right-hand position, and the winding of relay L to terminal 0.

Lamp y of group it of signal S is therefore now lighted by a circuit passing from terminal B, through the back point of contact I6! of relay L front point of contact I62 of'relay L and lamp y to terminal 0. Lamp 1' of group d of this signal is now lighted by a second circuit passing from terminal B, through the back point of contact I63 of relay L front point of contact I65 of relay L back point of contact I64 of relay L kand lamp r to terminal 0.

With relays L and L deenergized, and with relay L energized, a circuit is completed for energizing relays U and P by current of nega' tive polarity, periodically interrupted 80 times per minute by coder C This circuit passes from portion (1 of battery Q through contact I50 of coder C back point of contact I53 of relay L front point of contact I55 of relay L back point of contact I58 of relay L contact I59 of relay T contact I66 of relay T and windings of relays U and P in multiple back to battery Q On account of the current thus supplied to relays U and P being periodically interrupted, contact 5 of the relay U will close alternately at its front and back points. The current being of negative polarity, contact 6 of relay P will be closed in the right-hand position. During the periods when contact 5 is closed at its back point, a circuit will be completed for relay U and during the periods when contact 5 is closed at its front point, a circuit will be completed for relay L Relays L and L being slow releasing in character, will bridge the open periods of these circuits, and hence their contacts will be 'constantly closed at their front points. Lamp 11 of group it of signal S is therefore lighted by'its circuit passing from terminal B, through the back point of contact lei of relay L front point of contact I62 of relay L and lamp y to terminal 0. Lamp y of group :1 of signal S is lighted by a circuit passing from terminal B, through the back point of contact I63 of relay L front point of contact 555 of relay L front point of contact tee of relay L and lamp y to terminal 0.

A circuit is completed for energizing relay U and P by continuous current of positive polarity. This circuit passes from portion q of battery Q through the windings of relays U and P in multiple, contact I60 of relay T contact I59 of relay T back point of contact I58 of relay 19 front point of contact I55 of relay U and front point of contact I53 of relay L back to portion q of battery Q With relays U and P energized by continuous current of positive polarity, contact of relay U is constantly closed at its front point, and contact 6 of relay P is closed in the left-hand position. Relays L and L are therefore deenergized, but relay L is energized by its circuit passing from terminal B, through the front point of contact 5 of relay U, contact 6 of relay P closed in the left-hand position, and the winding of relay L to terminal 0.

Lamp g of group it of signal S is therefore lighted by its circuit passing from terminal B, through the front point of contact I6I of relay L and lamp g to terminal 0. Red lamp 1' of group (i is now lighted by a third circuit, passing from terminal B, through the front point of contact I63 of relay L back point of contact It'd of relay 1P back point of contact I66 of relay L and lamp r to terminal 0.

A circuit is completed for energizing relay U and P by current of positive polarity periodically interrupted at a frequency of 80 times per minute, passing from portion q of battery Q through the windings of relay U and P in multiple, contact ifiii of relay T contact I59 of relay T front point of contact I58 of relay L back point of contact I5'I of relay L back contact I56 of relay L and contact I5I of coder G back to portion q of battery Q With relays U and P energized by periodically interrupted current of .positive polarity, relays L and L are energized by circuits which are similar, respectively, to those traced for corresponding relays L and L and relay L is deenergized.

Lamp 9 of group u of signal S is therefore lighted by its circuit which is similar to that previously traced for lamp 9 of signal S". Lamp 1, of group 01 of signal S is lighted by a circuit passing from terminal B, through the front point of contact I63 of relay L back point of contact I61 of relay L front point of contact I66 of relay L and lamp ,1; to terminal 0.

A circuit is completed for energizing relays U and P by current of positive polarity periodically alternated with current of negative polarity from battery Q This circuit, when supplied with current of positive polarity, passes from portion :1 of battery Q through the windings of relays U and P in multiple, contact I60 of relay T contact I59 of relay T front point of contact I58 of relay L front point of contact E5? of relay L and the back point of contact 552 of coder C back to portion q of battery Q During the periods when current of negative polarity is supplied to this circuit, the circuit includes portion q of battery Q and the front point of contact I52 of coder C instead of portion q of battery Q and the back point of contact l52 of coder C Relays U is thus being energized 80 times per minute by current of positive polarity, alternately with current of negative polarity. Relay U is therefore energized 160 times per minute, and causes its contact 5 to close, at its front point and also at its back point, 160 times per minute. Relay P being similarly energized, its contact 6 will close in its left-hand position alternately with its right-hand position 88 times per minute. Each of the relays L L and L is therefore energized by its circuit which is similar to a corresponding circuit previously traced.

Lamp'g of group it of signal S is therefore lighted by its circuit which is similar to that previously traced for signal S Lamp g of group d ofv signal S is lighted by a circuit passing from terminal B, through the front point of contact I 63 of relay L front point of contact I61 of relay L contact 568 of relay L, and lamp 9 to terminal 0.

Referring now to Figs. 3 3 and 3, the stretch of track shown here is the same as that shown in Figs. 2 2 and 2 between points AA and EE. Whereas in Figs. 2 2 and 2 five complete rail way blocks are shown, only four such blocks are shown in Figs. 3 3 and 3. The signals shown in Figs. 3 3 and 3 are the same as the corresponding signals in Figs. 2 2 and 2 In Figs. 3 3 and 3, however the signals are controlled by traffic conditions in only four blocks in advance, whereas in Figs. 2 2 and 2, the signals are controlled by trafiic conditions in five blocks in advance.

In Figs. 3 3 and 3, the lighting of the lampsof each signal S is controlled by two line control relays, designated by the reference characters V and X with the exponent of the associated signal, which do not need to be of the code following type, and by a slow release relay, designated by the reference character 1) with the exponent of the associated signal, which is controlled by a front contact of the associated relay V. Each relay X is energized by current from a rectifier designated by the reference character D with a corresponding exponent, which, in turn, receives energy from the secondary winding I81 of an associated transformer designated by the reference character N with an exponent corresponding to that of the associated signal. The primary winding I85 of each transformer N is connected in series with the associated relay V in a line circuit controlled by the track relays for the first block ahead of the associated signal, and by the relays V, X, and v for the next signal in advance,

as well as by the coder C for the next signal in advance.

Each coder C operates at a low frequency of the order of cycles per minute, as in the apparatus of Figs. 2 2 and 2. In the arrangement here shown, contact I89 of each coder C is connected in multiple with a resistor unit NH. The opening of contact I86 of each coder C does not therefore open the associated line circuit, but merely reduces the current flowing in the line circuit by introducing the resistance I8I in series with the battery Q which supplies current to the line circuit.

As shown in Fig. 3, the track section immediately to the right of signal S is occupied by a train W. The indication displayed by each of the signals S under this condition, and the meanings of these indications are given in the following table.

I will now describe the manner in which these indications are displayed when train W is in the section immediately ahead of signal S Under these conditions, relay T is deenergized,and hence the line circuit for relay V and transformer N is open at contact I of relay T Relays V' 12 and X are therefore deenergized.

Lamp 1 of group u of signal S is lighted by a circuit passing from terminal B, through the back point of contact I92 of relay 0 and lamp 1' to terminal 0. Lamp 1' of the lower group d is lighted by a circuit passing from terminal B, through the back point of contact I94 of relay D and lamp 1' to terminal 0.

Relay V is energized by continuous current of positive polarity in a circuit passing from battery Q through a resistance unit I96, back point of contact I 83 of relay 11 contact I84 of relay T contact I85 of relay T winding of relay V primary winding I86 of transformer N and back point of contact I88 of relay 'U back to battery Q Transformer N does not respond to the constant unidirectional current flowing in this circuit, and hence relay X remains deenergized. With relay V energized in the normal direction, its front contact I9! is closed, and its polar contacts I9I and I96 are closed in their left-hand position. With the front contact of relay V closed, relay 12 is energized by a circuit passing from terminal B, through contact I91 of relay V and the winding of relay 11 to terminal 0.

With relay o energized, and with relay V energized by current of positive polarity, lamp 1 of group it of signal S is lighted by a circuit passing from terminal B, through front point of contact I92 of relay '01:, back point of contact I9370f relay X and lamp 1/ to terminal 0. Lamp 1' of group if of signal S is lighted by a second circuit passing from terminal B, through the front point of contact I94 of relay '0 contact I96 of relay V closed in the left-hand position, back point of contact I of relay X and lamp 1' to terminal 0.

Relay V is energized by constant current of negative polarity passing from battery Q through a resistor I90, contact I9I of relay V in its left-hand position, back point of contact I89 of relay X front point of contact I88 of relay '0 primary winding I86 of transformer N winding of relay V contact I85 of relay T contact I84 of relay T front point of contact I83 of relay 0 and back point of contact I82 of relay X back to battery Q Transformer N does not respond to the constant unidirectional current flowing in this circuit, and hence relay X remains deenergized. Relay V is energized in the reverse direction, and hence its polar contacts I9I and I96 are closed in their right-hand positions. With front contact I91 of relay V energized, relay v is energized similarly to relay 1: previously described.

With relay V energized in the reverse direction, and with relay 12 energized, lamp 1/ of group u of signal S is energized by a circuit which is similar to the circuit traced for lamp 1 of group it of signal S Lamp 11 of group d of signal s is lighted by a circuit passing from terminal B, through the front point of contact I94 of relay '0 contact I96 of relay V in its right-hand position, and lamp y to terminal 0.

Relay V and primary winding I86 of transformer N are energized by current of negative polarity, periodically varied by coder G over a circuit passing from battery Q through contact I80 of coder C in multiple with a resistor I8I, contact I9I of relay V in its right-hand position, back point of contact I89 of relay X front point of contact I 88 of relay 0 primary winding I 86 of transformer N winding of relay V contact I85 of relay T contact I84 of relay T front point of contact I83 of relay 19, and back point of contact I82 of relay X back to battery Q Transformer N and relay X are so proportioned that the periodically varied current supplied to primary winding I86 of transformer N will operate relay K through rectifier D The coded currentv of negative polarity causes polar contacts I9I and I96 of relay V to be closed in their righthand' positions.

Lamp g of group u of signal S is therefore lighted by a circuit passing from terminal B, through the front point of contact I92 of relay '0 front point of contact I93 of relay X and lamp 9 to terminal 0. Lamp y of group d of signal S is lighted by a circuit which is similar tothe circuit traced for the corresponding lamp of signal S Relay V and primary winding I86 of transformer N are energized by current of positive polarity, periodically varied by coder C over a circuit passing from battery Q through contact I80 of coder C in multiple with a resistor I 8|, front point of contact I82 of relay X front point of contact I 83 of relay v contact I84 of relay T contact I85 of relay T winding of relay V primary winding I 86 of transformer'N front point of contact I88 of relay 12 and front point of contact I89 of relay X back to battery Q Contacts I 9| and I96 of relay V are therefore closed in the left-hand position, and relay X is energized.

Lamp 9 of group it of signal S is therefore lighted by a circuit which is similar to the circuit traced for thecorresponding lamp of signal S Lamp 9 of group (1 of signal S is lighted by a circuit passingv from terminal B, through the front point ofcontactv I94 of relay 2%, contact I96 of relay- V closedin its left-hand position, front point of contact I95 of relay X and lamp g toterminal 0.

Fig. 4 shows a modification of the four-block signaling system provided in Figs. 3 3 and 3 The portion of the control apparatus at each signal, comprising a transformer N, a rectifier D and a relay X in Figs. 3 3 and 3, is replaced by a relay U and two slow releasing relays L in the arrangement of Fig. 4. In the arrangement shown in Fig. 4, each polarized relay V is of a type having neutral contacts which are slow to release. Whereas in -Figs. 3 3 and 3 each coder C periodically decreases the current supplied to its line circuit by opening its contact I80, the coder C shown in Fig. 4, periodically interrupts the current supplied to the line circuit for the next signal in the rear. The line circuits and the signal light circuits of Fig. 4 are similar to those of Figs. 3 and 3.

In Fig. 4, if relay 'I is deenergized by a train in the section directly ahead of signal S relays V and U will be deenergized. With relay U deenergized, relay L will be energized by a circuit passing from. terminal B, through the back point of contact 209' of relay U and the winding of relay L to terminal 0. Relay L will be deenergized since its circuit will be open at the front point of contact 209 of relay U With relay V deenergized, lamp 1* of group it of signal S would be lighted by a circuit including the back point of contact 205 of relay V and lamp r of group d would be lighted by a circuit including the back point of contact 201 of relay V With relays V and L deenergized, continuous current of positive polarity is supplied to the line circuit for the signal in the rear of signal S from battery Q through the back points of contacts 202 and 203 of relay V If the first block ahead of signal S is clear and the second block ahead is occupied, relay V will be energized by continuous current of positive polarity, supplied to the line circuit by the battery Q at the next signal in advance in the manner just described in connection with the line circuit for the first signal in the rear of signal S Relay U being therefore also energized by this same continuous current of positive polarity, will retain its contact 209 closed at its front point. Relay L will therefore be deenergized, and its contact 2I0 will be open, and hence relay L will also be deenergized.

Under this condition, lamp y of group '11. of signal S will be lighted by its circuit passing from terminal B, through the front point of contact 205 of relay V back point of contact 206 of relay L, and lamp y to terminal 0. Lamp 1' of group cl will be lighted by a circuit passing from terminal B, through the front point of contact 20'! of relay V contact I90 of relay V in the left-hand position, back point of contact 208 of relay L and lamp r to terminal 0.

With relay V energized by current of positive polarity while relay L is deenergized, current of negative polarity will be supplied by battery Q to the line circuit for the signal next in the rear, passing from battery Q through contact I9! of relay V in its left-hand position, back point of contact 204 of relay L front point of contact 203 of relay V and returning to battery Q through the front point of contact 202 of relay V and the back point of contact 20I of relay L.

If the first two blocks ahead of signal S are clear and the third block ahead is occupied, continuous current of negative polarity will be supplied to the windings of relays V and U in the manner just described in connection with the line circuit for the signal next in the rear of signal S The polar contacts of relay V will therefore be closed in the right-hand position, and relay U will be energized as before. Relays L and L will therefore be deenergized as before.

Lamp y of group it of signal S will then be lighted by its circuit previously traced. Lamp 1 of group d will also be lighted by its circuit passing from terminal B, through the front point of contact 201 of relay V contact I96 of relay V in its right-hand position, and lamp y to terminal 0. f

With relay V energized in the reverse direction, and with relay L deenergized, the relays V and U for the signal next in the rear will be energized by coded current of negative polarity flowing from battery Q through contact I80 of coder C contact I9! of relay V in its righthand position, back point of contact 204 of relay L front point of contact 203 of relay V and returning over the line circuit through the front point of contact 202 of relay V and back point of contact 20I of relay L back to battery Q.

If three blocks ahead of signal S are clear and the fourth block is occupied, relays V and U will be energized by coded current of negative polarity from the battery at the signal next in advance of signal S similarly to the manner just described for the relays V and U for the signal next in the rear of signal S With relay V energized by coded current of negative polarity, contacts I9I and I90 of this relay will be closed in the right-hand position. With relay U energized by coded current, contact 209 of this relay will alternately close at its front and back points causing relay L to be energized periodically through the back point of contact 209. Relay L being slow releasing in character, will retain its front contact 2! closed during the intervals between the closing of contact 209 of relay U at the back point. A circuit will therefore be completed for energizing relay L during the periods when contact 209 is closed at its front point, passing from terminal B, through the front point of contact 209 of relay U contact 2I0 of relay L and the winding of relay L to terminal 0. i

Lampg of group a of signal S will now be lighted by a circuit passing from terminal B, through the front point of contact 205 of relay V front point of contact 206 of relay L and lamp 9 to terminal 0. Lamp y of group d will also be lighted by its circuit previously traced.

Battery Q will now supply coded current of positive polarity for energizing relays V and U for the signal next in the rear by a circuit passing from battery Q through contact I80 of coder C front point of contact 20I of relay L front point of contact 202 of relay V and returning through the front point of contact 203 of relay V and the front point of contact 204 of relay L to battery Q.

If the first four blocks in advance of signal S are clear, the line circuit for relays V and U will be supplied with coded current of positive polarity from the battery for the signal next in advance of signal S similarly to the manner just described for the relays V and U for the signal next in the rear of signal S Relays L and L will now be energized as previously described in connection with coded current of negative polarity. Relay V on account of being ener-