US1718527A - Train-control system - Google Patents

Description

.Ime 25,-1929. T. E. CLARK ET AL TRAIN CONTROL SYSTEM Filed July 17, 1925 2 Sheets-Sheet i Hagi.. 2

A TTORNE Y.

June 25, 1929. T. E. CLARK Er Ax.

TRAIN CONTROL SYSTEM 2 Sheets-Sheet 2 Filed July V77 1.925

A TTORNEY.

Patented June 257 1929.

UNITED STATES 1,718,527 PATENT OFFICE.

THOMAS E. CLARK AND JAMES E. CLARK, OF DETROIT, MICHIGAN, ASSIGNORS TO CONTINUOUS TRAIN CONTR-OL CORPORATION, OF DETROIT,` MICHIGAN, A CORPO- RATION OF MICHIGAN.

TRAIN-CONTROL SYSTEM.

Application filed July 17, 1925. Serial No. 44,139.

rthis invention relates to thc control of railway trains by means of highfrequency oscillating currents propagated in or impressed upon the rails at intervals alone' the track bv means of transmitters and circuits betweeri the transmitters and thc track and current sources respectively, which instrumentalities are preferably associated with block signal systems along the track, and its object is to provide a system of this character whereby one of three signals on a locomotive is provided with energizing current whenever the locomotive passes along a portion of track in` which a current is propa gated having a. wavc length which is predetermined for track conditions which are to be indicated by that particular signal, such wave lengths varying according to the occupancy of the three blocks of track in advance.

Another object of 'this invention is to provide a brake mechanism for the locomotive and electrically controlled means for determining the operation thereof, three circuits therefor, a governor operatively connected to the locomotive to open and close a plurality of the circuits according to the speed of the locomotive, and means responsive to the currents in the track rails for selecting one of the three circuits to said electrically controlled means.

The tr ;n control system hereinafter described ofthe same general character as that shown and described in our Patent No. l.i"l2.i'8 dated irffv lll, 1929, and shown in the drawings associated with a signal system of the lthre lamp approach-light type connected to r divided into blocks, but it to be understood that our invention is not lin 'ted to use in connection with av signi of this character, but may be used with :inv desired type of signal system or muv be used without signal lamps.

This invention consi of a system of coneach embodying an electron or containing' a filament which ves current comparatively low voltthe tube being connected in an oscillaten'ibodying fixed and variable and inductances and means to condcnfers modify the circuit so that it will transmit currents of three different wave lengths to the track. one, which is hereafter termed the danger`J current. when the next or second track section in advance is occupied; a second, which is hereafter termed the caution7 current, when these two are unoccupied and the third sectionin advance is occupied; and a. third, which is hereafter termed Jdie clear current, when these three sections are unoccupied, and in connection with such track and the control stations, it comprises an installation upon alocomotive embodying collector' coils for cutting magnetic lines of force corresponding to thc several currents so as to create oscillating electric currents in the circuits of said coils, each circuit being tuned to the wave lengths of one of said currents, a signal for each collector coil circuit and adapted to receive current when its coil is energized by the magnetic lines of force produced by the track current to which it is tuned, and in anormally inoperative brake mechanism which is caused to operate when either of two predetermined currents is propagated in the track.

he invention also consists in collector coil circuits which each embody a. thermo-junction whereby the oscillating' current created in such circuit may be converted, and a polar relay controlled by a lplurality of the thus converted currents adapted to select the circuit between a current source and one or the other of two of said signals according to the current in the track rails.

It also consists in a normally clos cuit between a current source and an electro-pneumatic valve connected into the air brake system of the locomotive. which circuit is opened when one or the other' of two of said collector coil circuits energized, manually operable means, and an additional circuit adapted to be closed by said means to carry current from the current source to said electro-pneun'iatic valve and thereby )revent the application of the brakes.

It also consists in a governor' operatively connected to the locomotive and adapted to open two of the circuits to said electro-gueumatic valve. one after the other.r when the lo comotivc exceeds the speeds predetermined for danger7 and caution conditions at the ccntrol'stations of the blocks of track occupied by the locomotive.

It further consists in the details of construction illustrated in the accompanying drawings and particularly pointed out in the claims.

In the drawings, Fig. l is a diagram of a track signal station combined with our novel control station installation and a. diagram `of the instrumentality on the locomotive adapted to co-operate with the control station installation, the parts of the locomotive installation being in the positions they assume when responding to clear current in the track occupied by the locomotive. Figs. 2V and 3 are diagrams of these locomotive in, strumentalities when respondingto caution and danger currents in the tracks, respectively. Fig. 4 is a diagram of a transn mitter mechanism.

Similar reference characters refer parts throughout the several views.

The signal and train control installations positioned' along the track which are shown in Fig. 1 are substantially the same as those shown in our co-.pending lapplication Serial Number 36,628, filed June 12, 1925, and the transmitter shown in Fig. 4 is the same as the transmitter shown in Fig. 3 of that. application. The speed governor shown conventionally in Figs. 1, 2 and 3 is preferably that shown in our Patent No. 1,563,07 5, granted November 24, 1925. The signal installations, with which our novel train control installations are combined, as described in the first of the above named prior applications, embody lamp stands provided with three signalV lamps, preferaby green, yellow and red, which indicate how the track in advance is occupied, the green lamp show ing that the two blocks in advance are unoccupied, at which time the parts of the signal installation are said to be in clear positions; the yellow lamp showing that the second block in advance is occupied, at which time the parts of the signal installation are said to be in caution position; and the red lamp showing. that the next block in advance is occupied, at which time the parts of the signal installation are said to be in danger position. The lamps are respectively termed clear, caution and danger lamps. The track illustrated is that of one of two parallel tracks, each of which is set apart for traffic in one direction which is considered to be from right to left in Fig. 1. The blocks to like and the stations therefor are lettered B and C, and block B is supposed to be occupied while the three blocks in advance are unoccupied. For this reason, the parts of station B are in clear position.

Relays are shown in the drawings, each provided with one or more armatures designated by small letters, and in the following description, the armatures will be designated by their respective letters following the numeral designating the relay to which they belong. There such procedure is of advantage, a part of a station installation may be further designated by using the letter vof its block or station together with the numeral of the part. The next station in the rear is referred to` as station A, while the stations in advance as stations C, D and E, but none of these are shown, but they would be identical with station B shown in the drawings.

The rails 1 and 2 are divided into blocks by insulations 3 in the usual manner and adjacent the exit end of each block is a lamp stand 4 provided with red, yellow and green lamps. Adjacent each station and in part cont-rolling it is a track relay T connected to the rails at the exit end of the block by wires 5 and 6. These relays are energized by track batteries S which connect to the rails at the entrance ends of the blocks by means of wires 9 and' 10, resistances 11 being" used to prevent damage to the batteries when the rails are short-circuited by means of the axles of rolling stock.

At each station is a signal. battery 12 which connects to its lamp stand, whenever its block is occupied, by wire 13, armature 7C and wire 15. The return circuit is controlled bythe polar-neutral relay 14 which is energized by current from the battery 12 of the next station in advance, the current coming in over wire 16C. `When no current comes in over wire 16C, rela 14 is cle-energized; if positive current comes over this wire, polar armature 14d is swung clockwise; 1nd if negative current comes over wire 16, armature 14d is swung counterclockwise. No current passes to the signal lamps when relay 7 is energized and this relay is always energized except when its block is occupied.

l The direction of current in each wire 16 depends upon the occupancy of the block from which it extends rearwardly and upon the occupancy of the next two blocks in advance. Vvlith block E occupied. relay 7E is cle-energized and its armature b opens the circuit of wire 16 of block E so that no current flows to relay 14 of station D. Block D being unoccupied, relay 7D is energized but 14D is deenergized. Negative current therefore flows from the negative end of battery 12D over adjacent wires 13 and 25, armature 14a, wire 26, armature 7l and wire 16D to relay 14C and back over wires 23D and 24, armature 141 and wires 21 and 2O to battery 12D.

Relay 14C being negatively energized pesitive current flows from the positive end of battery 12C over adjacent wire 20, armature 14, wire 26, armature 7b (block C being unoccupied, this relay is4 energized) and wire 16C to relay 14B and back ercr wires 23C and 24, armature 14b and wires 25 and 13 to battery 12C. `Vlfhen no current flows to a station over wire 16, the parts assume the danger position and as soon the block of that station is occupied, current flows to the red or danger lamp over wires 2O and 21, armature c of cle-energized relay 14 and wire 17, and from the lamp stand over the cornmon wire 15, armature 7c and wire 13 to the battery. When negative current flows to relay 14 over wire 16, current Hows over wires 2O and 21, armature 14C, wire 22, armature 14d and wire 18 to the yellow lamp, and back to the battery as before described. lVhen positive current flows to ielay 14, its armature (Z swings to the position shown in Fig. 1 and current flows over wire 19 to the green lamp G. The current from the relay 14B returns over wire 23C, and over wire 24, armature 14h-and wires 25 and 13 of station C.

lVhen relay 14 of station B is de-energized, which occurs when block C next in advance is occupied, it is by reason ot the relay 7 of station C being cle-energized and opening the circuit between battery 12C and wire 16C at armature 7l. In that case, current flows from the nega-tive of battery 12B over wires 13 and 25, armature a; of de-energized relay 14, wire 26, armature b ot noi'- rnally energized relay 7B, and wire 16B to relay 14A.

It relay 14 of station B receives any current over wire 16C and block B is unoccupied, current Hows from the positive of battery 14B over wire 20, armature 14, wire 16, armature 7h to wire 16B. The ret-urn is controlled by armature 14" as betere described.

In Fig. 1, the circle indicates the transmission device for propagating high-tre` quency oscillating currents ot' diiliereiit wave lengths in the rails. Current is conducted to this device by means of the wire 63, which connects to the wires 2O and 21, and returns over the wire 64 connected to the wires 15 and 13 via armature 7C in its dropped position. It is therefore evident that no cui'- rent flows to the transmitter unless the rela 7 is (le-energized, that is, unless the block to which the transmitter is connected is occupied. This again makes for saving oi battery current.

As indicated in Fig'. 4, the wires 63 and 64 connect to a motor generator 65 and to the llanient 66 ot a vacuum or electron tube 67, an adjustable resistance 68 being provided in the tlanient circuit to control the teinperatui'e ot the tilanient. The wire 64 is also the conductor of the high voltage from one side of the motor generator 65 to the grid coil 80. which connects to the grid 72 by means of the wire 69, grid leal and condenser 71. The wire 73 from the other side of the motor generator connects to the plate coil 74 which connects to the plate 75 by means of wire 76. This coil is shunted by the variable condenser 77 whereby the oscil` lat-ions are transmitted to the rails 1 and 2 by means of the wires 78 and 79 from the loading coil 81, the wires 78 and 79 pretei1` ably connecting to the wires 5 and G. These oscillations are those which are transmitted when the next or second block in advance is occupied, that is, are of the dange7 wave length. A condenser 82 is shown connected into the wire 78 to prevent short circuiting ot the direct current trom battery 8 by the coil 81.

The polar-neutral relay 83 is energized by current received from the second station in advance over wire 84, and the neutral armature 83a connects the Wire 85, which shunts the plate coil 74, to the polar armature 83 which is swung clockwise by a posit-ive current over wire 84, under which condition the additional condenser 86 and wire 88 are brought into the circuit of this plate coil 74, and this polar armature is swung counterclockwise by a negative current over this Wire, when the second condenser 87 and wire 89 are brought into this shunt circuit. The shunt circuit embodying the condenser 86 so influences the current transmitter that clear wave lengths are propagated in the rails, and the circuit embodying the condenser 87 causes oscillations of a caution wave length.

Connected into the Wire 79, extending romthe transmitter 30 to the rails is a relay 90 which responds to these high-fre quency current-s, and attracts its armature a, closing a circuit to the slow 92, said circuit consisting of wires 64 and 93, armature 90, wire 94, relay 92, and wire to wire 63. The energized relay 92 attracts its armatures. As soon as the train T leaves block B, relay 90 becomes deenergized, butA relay 7 becomes energized, and a circuit is completed over wires 20, 21, 63 and 95 to the relay and wire 94, armature 92a, wire 96, armature 7c and wire 13 to the battery, and it remains so until its block is again occupied, when the first described circuit to this relay is again closed. The relay 92 being slow acting, it holds its armatiues during this change of circuits.

The relay 83 receives no current when either' of the two next blocks in advance is occupied. It receives negative current when the third block in advance is occupied and the first and second are unoccupied. It receives positive current when the three blocks in advance are unoccupied, and if we refer to station B, its relay 83 receives no current when relay 7 of either block C or D is fle-energized. It receives negative current when relays 7 of these two blocks are energized and rela-y 14 of station D is cle-energized. It receives positive current when relay 14D is energized by either positive or negative current from station E. The circuit from any station which controls relay 14 ot' the next station in the rear has already been traced.

Starting with the three blocks in advance of station B unoccupied, cui-rent from positive of battery 12 of station D Hows over its release relay lle;

wire 20, armature 14a, wire 20, armature 7b, wire 16D to station C, thence over its wire 97, to wire 23C to station B, thence over wire 98 of this station, armature 7 a, (block B being occupied) wire 84 to relay 83, thence over wire 29D to block C and armature 92b thereof, and over wire 99, armature 7a, wire 98 to wire 23D, and over this wire to station D, and over its wire 24, armature 14h, and wires 25 and 13 to the battery.

1f block E were occupied, current would flow from negative of battery' D12 over wires 13 and 25 to armature a of de-energized relay 14 of station D, and thence over the above described circuit to relay 83B. The return is the same until station D is reached when the current flows from wire 24 over armature 14h, wires 21 and 20 to positive of battery 12. These two circuits include armatures b of relay 7D and a of relay 7 C, which relays must be energized to hold these armatures in their' circuit closing positions, so that, if either block D or block C is occupied, the relay 7 connected thereto will be cle-energized and the energizing circuit to relay 83B will be opened, resulting in current of danger wave length being propagated in block B.

The length of track in which these currents are effective for affecting the instrumentalities on the locomotive will vary with the character of the current, but such lengths are preferably less than the lengths of the blocky sections so that there will be comparatively neutral. or non-energized lengths of track between energized lengths which are preferably at the entrance ends of the blocks adjacent the signal installations. rlhese non-energized sections permit certain of the instrumentalities on the locomotive to assume neutral positions for reasons which will be apparent later on.

r1`he currents propagated in the rails produce strong fields of magnetic flux just in front of the leading axle of the locomotive traveling the energized zone, and the lines of force probably pass around the rails and around the axle and bridge the gaps between the rails and axle by means of the wheels. Te have found that a very strong field exists just in front of the whee s of the leading axle.

Y The 20w-motive installation..

Mounted on the locomotive at an oblique angle to the rails and just in front of the leading axle of the locomotive in the strong fields of magnetic flux are three collector coils 100G, 100Y and 100B, connecting to thermo-junctions 101Gr, 101Y and 101B and vto variable condensers 102G, 102Y and 102B respectively. The circuits of these coils are tuned to respond to the magnetic flux produced by the currents whose wave-lengths denote clear,77 caution and danger positions in the control stations of the tracks occupied by the leading axle, to denote the conditions of the track in advance. The thermo-junctions or heater-current-converters may be of any desired type and convert the currents of the collector coils and it will be assumed that current passes from the thermo-junction 1011?u over the wire 105 to relay 103 and back over wire 106. The relay 103 when energized attracts its armature a. Current from the thermo-junction 101Y passes over the wire 100 to polar. relay 104 and back over wire 107, causing the relay 104 to swing its armature counter' clockwise while current from the thermojunction 101@ travels this path in the opposite direction and causes armature 104a to swing clockwise.

1li/hen the parts are as shownv in Fig. 1, current flows from battery 108 over wire 109, armature 104, wire 110, relay 111, wires 112 and 113 to the battery. 1t also flows over wires 109 and 114, armature a of relay 117 in dropped position, wire 115, armature 111a and wire 110 to green lamp 118 and wires 119 and 113 to the battery.

Then the parts are as shown in Fig. 2, current iiows from the battery over wire 109, armature 104, wire 120, relay 117 and wire 121 to the battery. 1t also flows over wire 114, armature 117L and wire 123 to yellow lamp 124 and wires 119 and 113 to the battery.

-When the parts are as shown in Fig. 3, current iiews over wires 109 and 114, armature 117% wire 115, armature 111n and wire 120 te red lamp 127, and wires 119 and 113 to the battery. rEhe lamps on the locomotive will therefore indicate the wave lengths of the currents propagated in the rails of the block then occupied by the leading wheels.

The brake mechanism comprises a vsolenoid 130, which, when de-energized, permits automatic application of the brakes as hereinafter described, but while energized, prevents such application. The circuit to this solenoid under clearl conditions (Fig. 1) is over wires 109 and 114, armature 117". wire 131, armature 111" and wires 132 and 133 to the solenoid, thence over wires 119 and 113 to the battery.

The speed governor is indicated by the circle 146 and embodies two arms 142 and 138 connected to the wires 139 and 140 respectively, which move out of engagement with the contacts at the end of the wire 141, the arm 142 when the locomotive exceeds the speed predetermined for danger conditions, say four miles per hour, and the arm 138 when the locomotive exceeds the caution speed, say twenty miles per hour.

Current normally iiows to the solenoid so long as relay 117 is cle-energized and relay 111 is energized. But when relay 117 is key 144, wire 145, key 143, wire energized, which occurs when armature 104 closes the circuit over wire 109, armature 104, wire 120, relay 117 and wires 121 and 113, which occurs when collector coil 100Y carries current, or when relay 111 is deenergized, which occurs when relay 103 is energized by current from coil 100B and opens the circuit oveil wire 109, armature 103, wires 135 and 136, armature 117C, wire 137 armature 111C and wire 110 to the battery, the circuit to the solenoid 130 is broken and the brakes will be applied automatically unless the engineer and fireman are alert and depress the forestalling keys and the engineer operates his brake valve to bring the speed of the train down to that indicated by thc signal lamps. lf the yellow lamp burns, as indicated in F 2, the forestalling keys 143 and 144 may be depressed, and as soon as the train speed has been reduced to that predetermined for caution conditions, the circuit closed by these keys will be over wires 109 and 114, armature 117, wire 139, arm 142, wire 141, wire 147, 148, relay 149 and wires 150 and 113 to the battery. The energized relay 149 attracts its armatures and closes two circuits, one between the wires 141 and 148 by way of its armature c and wire 152, which carries current so that this relay remains energized until the speed is increased beyond that predetermined for caution, or until a danger current is picked up by coil 100B, when relay 117 becomes cle-energized.

The second circuit closed by this relay 149 upon depression of the keys is between the wires 133 and 141 through the medium of armature 149, so that the solenoid 130 will again receive current and continue to receive it until the circuit between wires 139 and 141 is opened by the caution arm 142 of the governor, or until the danger coil 100R picks up current.

Then this occurs the circuit to relay 117 is opened by armature 103a and the circuit from the battery to the caution arm 142 of the governor is opened by armature 1171. But this armature 117b closes a circuit over wire 131, armature 111D and wire 140 to the danger arm 138 of the governor. lhen armature 1171) dropped,.it opened the circuit to relay 149, as shown in Fig. 3, so that solenoid 130 is de-energized. The engineer must now bring his train down to danger speed, at which time the danger arm 138 of the governor closes the circuit between wires 109 and 147. If the two keys 143 and 144 are now depressed, a circuit to the relay 149 is again closed so that the solenoid may again be energized. The second circuit to this relay is again established by armature 1495*.

As soon, however, as the locomotive leaves a caution or danger track section and enters a clear section, current will again pass to relay 111, which is provided with three armatures, one to close the circuit to the green lamp, the second to close the circuit to the solenoid, and the third to close an auxiliary circuit for the relay itself.

It will therefore be seen that as the train is running along under clear conditions, a green lamp will burn steadily in the cab. The circuit to the green lamp 118 is as follows: from the battery 108 over wire 114, dropped armature 1172*, wire 115, armature 111, wire 116, lamp 118 and wires 119 and 113. The relay 111 is kept energized by its stick circuit from battery 108 over wire 109, dropped armature 103, wires 135 and 136, dropped armature 117C, wire 137, armature 111, wire 110, relay 111, and wires 112 and 113 until relay 104 is negatively energized by current picked up by coil 100Y, resulting in relay 117 being energized, or until relay 103 is energized by current picked up by coil 100B. As soon as the train enters a track section carrying caution current, the green lamp will be extinguished and the yellow lamp burn. The circuit to the solenoid will be cle-energized and remain so until the train is brought to caution speed and the two forestalling keys are depressed. The train may now go ahead at caution speed until it enters a danger section, whereupon it must be slowed down to da-nger speed. If the engineer fails to slow his train and if either he or the fireman fails to depress his forestalling key, the brakes will be automatically applied and the train brought to a stop.

Vhile any desired type of valve mechanism may be employed, that shown conventionally in Figs. 1, 2 and 3 has been found available. The well known engineers valve 155 is employed to admit air from a pressure tank to the train pipe 156 to release the brakes and to relieve the pressure in this pipe to cause application of the brakes. The valve 157 is connected to the core of the solenoid 130 and normally prevents flow of air from the pipe 158, connecting to the main pressure tank. But when this valve drops, as shown in Figs. 2 and 3, air flows through the pipes 159 and 160 to the cylinders 161 and 162.

A piston 163 is slidable in the cylinder 161 and connects to a valve 164, which, when air under pressure is admitted to the cylinder 161, is forced to the right in Fig. 1 and closes the main passage from the valve 155 to the train pipe, thus preventing increase of the train pipe pressure. It may be decreased, however, as the check valve Y 165 permits air to flow from the train pipe to the valve 155.

The pipe 158 connects to the valve chamber 167 by means of a pipe 168 and this chamber embodies a cylinder 169 for the piston 170, to which is connected a valve 171 which normally prevents the discharge of air from the small orifice 172. A second cylinder 162 contains a piston 174 which connects to the valve 175 by means of a hollow rod 176 so that when in the position shown in Fig. 1, air from the pipe 168 fills the space on both sides of the piston 170, but when the parts are move-d to the positions shown in Figs. 2 and 3 by reason of air under pressure from the pipe 159, airl from above this piston 17 O lows'tothe vent 177 through the holes 17 8 in the hollow rod 176. A reservoir 180 is connected into the valve chamber' in order `to store sufiicient air to make the reduction in pressure above the iston 17 0 comparatively slow and thus allow ample time for the ret-urn of the electro-pneumatic valve to normal position upon the ldepression of the forestalling keys, as above explained, before the train pipe ypressure is reduced sufficiently by the escape of air from the small orifice 172 to caus'eapplication of the brakes. But when the air above the piston 170 is suiiiciently reduced, the pressure below this piston will lift it together with the valve 171 and the air in the train pipe will escape from the orifice 172 and the brakes will be applied. The pressure in the cylinders 161 and 162 Iescapes through the vent/181 as soon as the electro-pneumatic valve is returned to normal position by the solenoid 130.

The present. invention does not include the valve mechanism or any of the other details beyond the solenoid 130, and 'any other desired device may be substituted therefor by those skilled in the art of railway brakes. Neither does the present invention comprise the details of the relaysparmatures, lamps or current transmitters and we therefore do not wish to be limited to any of the details of construction. llVhere the word locomotive is employed, we wish to include all types of automotive vehicles equipped with power brakes of whatsoever character the automatic application of which may be brought about or prevented by means of a solenoid of the character described.

We claim 1. In a train control mechanism adapted to be installed upon a locomotive equipped with power brakes and adapted to travel on rails to which control stations are connected at intervals along the track for the purpose of propagating therein electric currents of three different wave lengths according to the condition of the track in advance,fthe combination of three electric signals, a current source, circuits between the signals and the current source, a pair of relays to control said circuits, and a collector coil and a circuit therefor tuned to respond to each of said currents in said track,one of said relays being a neutral relay` and connected to one collector coil circuit and anotherrelay being a polar relay and connected to the two other collector coil circuits.

2. In a train control mechanism adapted to be installed upon a locomotive equipped with power brakes and adapted to travel on rails to which control stations are connected at intervals along the track for the purpose of propagating therein electric ourrents of three different wave lengths according to the condition of the track in ad- Vance, the combination of a current source, an electropneumatic valve'controlling said power brakes, a circuit between the current source and valve to energize the valve to prevent automatic application of the brakes, a neutral relay to keep said circuit closed, an energizing circuit for said. relay, a polar relay controlling said energizing circuit, two collector coils and circuits therefor timed to respond to said currents in said track, and conductors connecting said collector coil circuit-s to said polar relay, said relay being energized by current from one coil circuit to close the energizing circuit to said neutral relay and by the current from the other coil circuit to open said energizing circuit.

3. In a train control mechanism adapted to be installed upon a locomotive equipped with power brakes and adapted to travel on rails to which control stations are connected at intervals along the track for the purpose of propagating therein electric currents of three different wave lengths according to the condition of the track in advance, the combination of a current source, an electropneumatic valve controlling said power brakes, a circuit between the current source and valve Vto energize the valve to prevent automatic application of the brakes, a neutral relay to keep said circuit closed, an energizing circuit for said relay, a polar relay controlling said energizing circuit, two collector coils and circuits therefor tuned Ato respond to said currents in said track, conductors connecting said collector coil circuits to said polar relay, said relay being energized by current from one coil circuit to close the energizing circuit to said neutral relay and by thc current from the other coil circuit to open said energizing circuit, a second circuit between the current source and said neutral relav, and manually operable means to close said second circuit.

a. In a train control system for railways having tracks divided into blocks and means to propagate higlrfrequency currents of three diflferent wave lengths in the rails of the several blocks, depending upon the presence and proximity of the next train ahead, asignal apparatus on the vehicle embodying three lamps, a current source, circuits between said current source and said lamps, and control means responsive to the electric energy in the track rails Vfor rendering one or the other of said lamps effective, said control means embodying three collector coils and circuits therefor positioned adjacent but spaced from the rails.

5. In a train control system tor railways having` tracks divided into blocks and means to propagate high-frequency currents oi'l three diterent wave lengths in the rails ot the several blocks, speed control apparatus on the vehicle including` means permitting the vehicle to proceed at maximum speed and other means permitting the vehicle to proceed at two restricted speeds, and control means responsive to the electric energy in the track rails l r r n lering,r one or the other of said means el? ive dependingl upon the proximity of the next train ahead, said control means embodying three colleen coils and circuits therefor positioned adjacent to but spaced from the rails, current transiormers to change oscillatingl currents to direct currents, and relays energized y said direct currents.

G. a train control system for railways having tracks divided into blocks and means to propagate high-frequency currents ot' three dilferent wave lengths in the rails of the several blocks, speed control apparatus on the vehicle including' a current source, an electro-pneumatic valve, circuits therefor ot' which ene permits the vehicle to proceed at maximum speed, and speed responsive means permitting` the vehicle to proceed at two re tricted speeds and adapted to open the circuits to the electropneumatic valve when the selected predetermined exceeded, and control means responsive to the electric currents in the track rails and including a collector coil for each et said wave lengths for rendering` one or the other of said speed responsive means ctlective.

T. in a train control system for railways having tracks divided into blocks and means to propagate high-frequency currents et three dilterent wave lengths in the rails ot the several blocks, speed control apparatus on the vehicle embodyinicg a normally closed electro-pneumatic valve adapted to open when 1leenergized to cause the application ot' brakes, a current source to energize said valve, three collector coils and circuits therefor mounted adjacent to and spaced speed is apart from the track rails, each circuit being; responsive to one of the electric currents propagated in the rails, relays connected to and influenced by said collector coils, a normal circuit between the current source and said valve adapted to be closed when one of said collector' coils is energized and to be opened when either of the other two coils is energized, two additional and normally open circuits between the current source and said valve, manually operable means to close said circuits, and speed responsive means connected into said additional circuits and adapted to open them as the vehicle exceeds the speeds determinciil therefor.

S. ln a train control system for railways having tracks divided into blocks and means for propagating higlrt'requency currents of three dili'erent wave lengths in the rails of the several blocks according to the condition oi the trac` in advance, the combination of a current source on a vehicle, speed control apparatus on the vehicle adapted to permit he vehicle to proceed at maximum, minimum and intermediate speeds, and means on the vehicle responsive to the electric energy in the track rails and comprising a collector coil for each of said currents to control the operation of said speed control appr-ratus and thereby cause the vehicle to respond in speed to the current in the track rails. I

9. In a train control system for railways har/ing` tracks divided into blocks and means t'or propagating high-frequency currents of three different wave lengths in the rails of the several blocks according to the condition et the track in advance, the combination of a current source on a vehicle, speed control apparatus on the vehicle adapted to permit the vehicle to proceed at maximum, minimum and intermediate speeds, and means on the vehicle responsive to the electric energy in the track rails and including current receptive means adjacent said rails to control the operation et said speed control apparatus and thereby cause the vehicle to respond in speed to the current in the track rails.

THOMAS E. CLARK. JAMES E. CLARK.

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