US1575579A - Train control - Google Patents

Description

March 2 1926., I

I 1,5?5579 W. K. HOWEy TRAIN coNTRroL Filed Jan. 4,- 1924 ,2 Sheets-Sheet 2 ZU [yf-FA'TOR.

(dm AT'TURNEY Patented Mar. 2, 1926.

UNITED STATES ,PATENT OFFICE.

WINTHBOP K. HOWE, 0F ROCHESTER, NEW YORK,A ASSIGNOR TO GENERAL RAILWAY d SIGNAL COMPANY, QFROCHESTER, N EW YORK.

TRAIN CONTROL.

Application filed January 4, 1924. Serial No. 684,857.

To all whom it 'may concern:

Be it known that I, WINTHROP K. I-Iown,v a citizen vof the United States of America, residing at Rochester, in the county of Monroe and State of New York,I` have invented certain new and useful Improvements in Train Controls, of which the following is a specification.

vThis invention `relates to train control systems of the'intermittent inductive' type.

In applying automatic train control to railways with the idea of controlling the speed of the train in accordance with traftic co-nditionsahead, it has been found that the speed limits at various points of caution blocks vary considerably depending on the type of train used, thegrade of the track, the length of a particular block and various other conditions; whereas the permissive speed which a train may attain .in a danger block is some predetermined low value constant for any block regardless of grade, or the like.` It therefore appears to be expedient to set up speed limits along the track in caution territory dependent on the trackway conditions (length of the block, grade ofthe trackway, etc), and to set up a predetermined continuing speed limit for the train when moving in a danger block which persists throughout the entire length of such block.

lVith the above and other considerations in mind it is proposed in accordance with the present invention to apply apparatus which enforces predetermined speed limits at predetermined points in a caution block in accordance with the time-distance interval principle, that is, automatically apply the brakes 1f the train consumes less than a redetermined time in running a predetermined distance at certain points in such caution block; and-to provide additional apparatus on the car, including a speed-responsive device,

whichv is automatically rendered active upon 'the entrance of the traln into a danger or occupied block to apply the brakes if the train Aduring its travel through such danger block exceeds a predetermined minimum speed, and which is automatically rendered vinactive so as to remove the minimum speed restriction upon entering a clear or caution block. l

or overnor driven More specifically, it is proposed to provide inductive influence communicating means of the intermittent type which cooperates with suitable relaysy and a time element device on the railway vehicle to apply the brakes of the vehicle if two successive control influences are transmitted /.from the trackway in less than a predetermined period of time; to provide penalizing means' which requires' the engineer to manipulate certain resetting apparatus, which is only accessible from the ground, each time an automatic brake application has been inflicted by this time-distance interval mecha-y nism, the operation of this resettingmechanism restoring the automatic brake control device and the time-distance interval mechanism but not restoring all of the car-carried mechanism so that a 'certain continuing speed limit will still be imposed after such penalty has been intiicted; to provide suitable resetting or restoring means which', is entirely automatically operated only under clear or caution traffic conditions ahead which is also accompanied by transmitting an inductive control influence from the trackway to the moving vehicle, `this automatic restoring operation putting the carcarried apparatus back in lts original clear trailic condition. It is thus apparent that if an automatic brake application hasl taken place' in a caution block and the engineer has stepped to the ground and operated the manually operable restoring or resetting device that a certain predetermined speed limit imposed by a speed-responsive device vehicle is still effective and that this speed limit cannot be exceeded until' an automatic restoring control influence has been transmitted -from the trackway which is only possible'` under clear or caution traffic conditions ahead.` It is thus seen that the s eed control apparatus effective in a danger b ock is initiated bythe reception of two control influences in less than a predetermined time in a caution block. In order to make it ver 'difficult lfor a train to pass entirely throng a caution blockl without receiving two control ,influences from the trackwa in less than a predetermined time, the evioes of the last pair of trackway-devices for transthe wheels of they -in danger territory a suitable acknowledging devicehas been provided. This acknowledging device cooperates with the various elements of the car-carried apparatus in a manner so thatthe penalty (manual resetting operation) isnot inflicted if the acknowledging device is operated but the Jdanger territory speed restricting apparatus is initiated by such operation of this acknowledging device. In other words, the engineer 1s encouraged to operate an acknowledging device because it removes the penalty heretofore mentioned, but by such operation he himself initiates the danger speed control apparatus. The combined eifectof the spaced trackwa devices which require the trainto be moving at less than three miles per hour to initiate the dangerl control apparatus, and the provision of the acknowledging device, the operation of which also initiatesthis danger control apparatus, is believed to substantially assure initiation of this apparatus upon the entrance to a danger block.

Another object of the present invention relates to the provision of automatic restoring trackway devices located at an intermediate point'in a block, so that, if the train enters a danger block and this block changes to a caution or clear block while the train is moving therein and before it reaches such intermediate point, a restoring control 1niuence is transmitted to the train at such point, so that it may again proceed at either a caution or a clear speed depending on traic conditions in the next block i'n advance.

In. describing the inventionv in detail reference will be 'had to the accompanying drawings in which Fig. 1 is a circuit diagram of the carcarried apparatus and the trackway apparatus illustrating one embodiment of the present invention, in which the various elements have been shown conventionall Fig'. 2 shows the major portion an exit end of a block, direction of traiic being as indicated by the arrow and illustrates the trackway restoring apparatus which is controlled by a relay connected in series with the trackway; and

Fig. 3 illustrates a portionof the system as shown in Fig. 1 1n which a modified form of restoring influencecommunicating meansl is employed.

*I Track'way apparat/us.' .Referring more particularly to the lower art of Fig. 1 of the drawings,' there has geen shown in a conventional manner a railway track having rails 1 divided by insulating joints 2 into blocks in the usual manner, the block I and the adjacent ends of two other blocks H and J being shown. Since the various blocks are the same, like parts of each block have like reference characters with distinctive exponents assigned thereto. The block I is provided with a suitable source of energy at the exit end, which has been shown conventionaly as comprising a battery 3, and a track relay 4 of the usual construction at the entrance end to this block. Although wayside signals of any one of the various commercial types, such as color light signals, position light signals, semaphore signals lor the like may be used, semaphore signals Zhave for convenience been shown conventionally, without illustrating their well-known circuits and devices. As heretofore mentioned, the car-carrie apparatus is constructed on the principle that the receptionof'two control inliuences from the trackway in less than a predetermined time causes an automatic brake application as a result of excessive s ed. In order to tra smit such control influences pairs of suitzdile trackway devices are provided', and the devices ofthe respective pairs are spaced along the track distances depending on the speed to be enforced at such polnts. In order to control such trackway devices in accordancewith trafc conditions V in the block ahead, a line relay 5 is provided for each pair of devices. These line relays 5 for each block are connected in multiple across a line wire 6 and a common wire, not shown but having a connection thereto designated C. The line wire 6 of each block is connected to a suitable source of energy, designated B, through a front lcontact 7 of the track relay of the block in advance.

Each of the trackway devices com rises a core 10 of ma netic material preferab y laminated and oil general U-shape, the legs of which terminate in enlarged pole pieces 9. The second device of each of these pairs ot trackway devices is rovided with a wind-- ing 11 on the back yoe thereof. This winding 11.is connected in a closed deener ized circuit of low resistance includingxthe ont contact 12 of the corresponding line relay 5, for purposes more clearly described in connect1on with the operation hereinafter.v Since these trackway devices are the same, the trackway devices which have a coil are designated by like reference characters having distinctive exponents a, b, c and d. Near the exit end of the block are provided threesuch trackway cores 10 each of which is provided with a winding 11. These threetrackway elements are so spaced that`the first two enforce a speedlimit by the time-distance interval principle of say` elements are spaced tov enforce a speed limit of say three miles per hour-,heretofore mentioned. These last three elements are spaced in the manner just mentioned so that they will serveas two separate pairs and also as part of the restoring trackap aratus to be presently described. The mlddle element of these three trackway devices comprises one element of a so-called trans former scheme restoring device T for transmitting inductive restoring influences. The other element of this transformer scheme comprises a core 13 having pole pieces 1.4 and a coil 15 on the back yoke thereof which is substantially identical in construction to that of the other trackwayelements or devices. Thestrackway apparatus comprising Oar-carried apparatus.

Oar @lamentar-On the railway vehicle, which has been shown conventionally by the axles 19 and wheels 20, are mounted a knockdown-car element KD which is adapted to receive control influences toI restrict thel movement of the vehicle and a restoring ele-V ment RS for receiving favorable proceed or restoring iniuences. These 'elements are preferably mounted on" the railway vehicle in`suitable non-magnetic casings spring supported from the track of ysuch vehicle in a manner so as to cause them to pass directly overthe righthand and left hand trackway 4 elements heretofore described, so that they may communicate through an intervening air gap, say, from 11/2 to 3 inches.

This knockdown element KD comprises a core 21 of general inverted U shape preferably constructedl of a high grade of lami- Vnatedmagnetic material terminating in enlarged pole pieces 22. On one of the legs of .this core' 21 is supported a primary coil P, which is adapted vto set up a certain magneto-motive-force lin the core when energized. On theother leg ofthis core 21 is provided asecondary coil S 4for purposes more clearly .described hereinafter. The restoring infiuence receiving car-element'. 'RS

com rises a similar core 23 terminatino in pole j iiecesQl. 0n the legs of this core 23 are provlded coils l25 connected 1n serles for purposes pointed {6i-1t hereinafter.

Balma-The car-carried a) aratus in, c

cludes suitable sensitive and quick acting relays CR, RR, BR, and DR, and a timev element device hereinafterdescribed. Cer` tain of these relays are connected in circuits and assume certain positions depending on the sequence of operation of certainother relays. Although theserelays may' take any` one of the various Well-known forms, they preferably are relays'of the tractive armature type,'in which the armature is pivotally mounted for movement about a vertical axis and in which the armature is well-balanced so as not to be responsive to vibrations in either a vert-ical or a horizontal plane.` The armatures of these relays are preferably Very light so as to reduce the moment of inertia to a minimum, thereby causing them to be quick acting in response to a slight change of current in thelr energizing circuits. '.lhe contacts operated by these relays can more conveniently be described in connection with the circuits which they control j andl lwill be mentioned more particularly hereinafter.

Brake cont/0l lavica- On the railway.

vehicle is provided a suitable device for automatically applying the usual air brakes of the train, which in the particular instance has* been conventionally illustrated as an electro-pneumatic valve EPV. This brake control device EPV is of the normally ener. gized type and is adapted to vent the brake pipe in any 'desired manner if deenergized.

IThis device EPV may control suitable actu- Y ating means which moves the usuali engineers brake 'valve to'the service brake applying position when the device EPV is deenergized.; it may vent the brake pipe directly and simultaneously therewith cut off main reservoir pressure from the -engineers brakel valve, so that the engineer cannot prevent an automatic brake application by recharging the brake pipe; or it may operate certain-brake applying means which vents the brake pipe'to a predetermined extent only, b therewith cut air presand simultaneous] sure off of the engmeers 'brake valve so'that v he cannot recharge the train line:

Speed indicator o1 go-vcmo1'.-Another element of the car-carried apparatus com.- prises a speed responsive device for continuously indicating the speed of the trainand -for conveniencel a' governor` (Jr of theicentrifugal type has been shown. This governor G consists of a shaft Q8 operatively con' `nected to the wheels 9.0 or axles 19 of the vehicle. ',lo'this governor shaft -28 is pinned.

-a bushing 29 which is connected to acirl cumferentially grooved sleeve 30 slid'ably mounted onzthe shaft by links 3l-having a. weight 3'2 at the junction of these links,. .;The sleeve 30 is normally maintained in its highest position by a compression coil spring 33 contained about the shaft 28. It is thus noted that the sleeve 30 will assume its l highest position when the shaft 28 is at rest, but will gradually assume lower positions b reason of the centrifugal force acting on tlie Weights' 32 pulling the sleeve 30 down against the opposition of the compression coil spring 33 in response to rotationof the shaft28; A contact arm`34v pivotally secured on a pin 35 has a forked end projecting therefrom engavinglthe grooves in the sleeve 30, so that this contact'arm 34 moves about its pivot in response to a change in speed ot' the vehicle. A stationary contact 36 is provided which is in contacting relation with the portion 37 of the contact arm for all speeds of less than, say, 20 miles `per honr. A similar stationary contact 38 is provided whichis in contacting relation Vwith the portion 39 of the contact arm at Speeds above 20 miles per hour, for purposes more clearly described in connection with the operation of the system.

l*which is Time element devices-In order to auto-y matically apply the brakes if two successive control influences are received in less than a predetermined time a time element device TE is employed. This time element device TE operates on the principle of acceleration and deceleration of a given mass similar to the principle employed in watches of the usual construction. This device TE comprises a shaft 42 having a ily wheel 43 of non-mag. netic material pinned thereto which has an armature 44 of the nsualtractive iron type fastened to the periphery thereof. This fly wheel or balance wheel 43 is biased by a tion as indicated by the arrow on this balance wheel. This spiral spring has its one end anchored to .a sleeve 45 of a pinion 46 held in a predetermined position under normal conditions by a rack 47. On the shaft 42 are provided a normally closed contact 4S and anormally open contact 49 which make and break certain circuits in a certain sequence each time the time element device TE performs a cycle of operation.

Adjacent thebalance Wheel 43 -is supported an electromagnet comprising two coils 50 (only one of which has been shown), which vWhen energized maintain the armature 44 in engagc1nent \vith the residual pin 51 ot' this timing magnet TM.

By looking at the time element device TE vit will be noted that the balance wheel 43 rotates in \a counterclockwise direction by reason of the spiral spring 41 'acting on the pin 52 fastened in the balanre wheel 43 as soon as this timing' magnet TM is deencrgized. The inertia ot' the. balance wheel 43 carries the rotation ot' this wheel beyond the point of zero tension ofthe spiral spring 41 through an angle ol substantially-1350, so that the total are of movement is substantially 2700 as' shown by the dotted position of the contacts 1S and 49. This particular arcof movement is of course not necessary, but has been shown to illustrate the functioning of the system. With the spiral spring 41 biased in the opposite direction it urges the balance Wheel in a clockwise direction, and causes it to almost return to its original position. .If now the timing magnet has again been energized in the meantime it attracts the armature 44 and again holdsthe time element device TE in its normal position. If for any reason this time element device assumes its biased or intermediate position it may be restored toits -normal position by rotation of the pinion 46 in a clockwise direction far enough to carry the-balance wheel back to its initial position.

In order-to restore this time element device TE to its normal position by rotating the pinion 46, a cylinder 55 having a piston 56 therein, which is maintained in its normal position by a compression coil spring 57, is

provided. This piston 56 is connected to tle rotated 1n the clockwise ldirection substan-l 'tially 135o before the armature gets back to a position Where it may be attracted by the timing magnet. It the timing magnet is energized, asA it would be under ordinary conditions, 4the balance wheel will be held in its normal position, as shown in the drawl ings. Upon return of this valve to its normal position compressed air again lojvvs from the cylinder 55 to atmosphere through a suitable exhaust port (not shown).

Operation. i

Normal condition of apparaitra-In order to simplify the Wiring diagram of the car' carried apparatus one terminal of. a suitable source of energ f has been designated B, the other terminal being connected to a commonl return wire'C (not shown). The terminals B may of coursebe the terminals of different sources ot' energy or any one of several difl ferent taps of a common source of energy. such as a battery. Under normal clear tra t'- iic conditions as shown in Fig. l of the dran'- ings ,the electro-pneumatic vdevice EPV and the primary coil P are connected in series in an energized circuit which may be traced as follows beginning at the terminal B- of al suitable-source of energy, wire 60, front contact 61 of the danger relay I)l{,r Wires 6:2 and 63, front contacts 64 of the brakccontrol control device EPV, wire 66, contact v67 on the rack 47, wii'e 68, primary coil P, wire 69,

back to the common return Wire C.

The flow of current in this circuit, as lieretofore mentioned produces a certain magneto-motiveforce in the knock-down car relays RR and element KDv which sets up a certain leakage of magnetic ux around the primary coil 1*, l

trol ielay-C/Rfavires'73 aid 74, secondary coil S of the car element KD, wires 75, winding ofthe control relay CR, wire 76, back to common return wire (l.

With the control relay CR in its energized p0sitionan ener izing circuit including the ,R in series is completed which may be traced as followsbeginnigg from the normally at the terminal B, wire 71, front contact of the control relayv CR, wire 78, Winding .of the repeater relay RR, wires 79, '80and 81, winding of the brake control relay BR, wires 82 and 83, front contact 84 of the brake control relay BR, wire 85, back to the'eommon return wire C.

Part of the current for energizing the brake control relay BR. under .normalclear traic conditions, as shown, does not flow. through the repeater relay RR-but is derived closed contacts of the time element device TE and flows througdr the following circuit :beginning at the terminal B of a suitable source of energy, wire 86, contacts 87 and 48 of .the time elementFLY device TE, wire 88, resistance unit 89, wires 90, 80 and 8l, winding of the brake control relay BR, wires 82 and 83, front contact 84 of brake control relay BR, wire 85, back to 'common return wire C Thus, opening of the front Contact 77 of the control relay CR merely deenergizes the repeater relay,7 RR but not`necessarily deenergizes the relay BR, because this .relay BR may be held up bythe current flowing in the last traced circuit. With the brake-control relay BR- in its energized position, the danger relay DR ma be maintained energized through the 'f0- lowing stick circuit z-beginning -at the terminal B of a suitable source of energy, wire 1 92, lower winding of the danger relay-DR,

wire 9 3, front contact 94, wires 95 and 96, acknowledging push buttonvswitch' 97, Wires 98 and 99, front contact 100 of thebrakel control relay BR, wire 85 back to the common return wire C:

ln connection with the stick circuit )usttraced .it should be noted that operation of theacknowledgn pushlbutton 97 will in terrupt this circuit, providing the speed of the trainis less than 20 miles per hour; but 1f the speedis above 20 miles per hour, the acknowledgin push button contact 97 is 'shunted by t e contacts 38 and 39 of the governor G, and therefore these governor contacts will prevent interruption of the stick circuit at speedsabove this limit, even though the push button is depressed.

With the repeater relay RR in its energized position, a circuit is completed for the timing magnet TM asl folloWs:-beginning at the terminal B, Wire 102, front contact 103 of the repeater relay' RR, wire 104, winding 5 0 of the timing magnet TM, Wire 105, back to the common return wire C, the completion of which causes the armature 44 and the balance wheel 43 to be held in their normal position as shown.

The upper winding of the danger relay DRfis connected in a closed deenergized cirf cuit in series with the coils 25 of the re storing ear element RS which may readily be traced, in the drawings.

Caution condition (speed not emessi/vc) .-f Let us assume that the vehicle with the as'- sociated car-carried apparatus as shown in Fig. 1 is moving in the block H in the normal direction of traffic, as indicated by the arrow, when the block J is occupied by antrack relay'4, Vthereby causing deenergization of the line relays', and openin of the normally deenergized circuits for t e coils 11 and 11* of the pairs of trackway elements. Also, with thetrack relay 4 deenergized, the windings 11",` 11 and 11d. of the last-*three track elements in "a caution blockare in an open circuit, so that all ofthe track elements function like a U-shaped core of unmagnetized material. 4

As the train in question asses into the block I a distance to cause t e knock-down element K D to coineinto communicating relationship with the rst track element out the first pair of elements, the reluctance of the magnetic eircuit'includingthe car-carried core 21 is momentarily reduced. This reduction in the reluctance of 'his magnetic l circuit causes a sudden increaseof flux to take place through the secondary coil S on one leg of thiscore 21. This sudden increase' of flux through the secondary coil S is due 'to a large extent, it is believed, to the diver- D recedes from this a track element the flux passing through the of the control relay CR, substantially-the same as a single cycle of alternating current potential. The secondary coil S is so connected in this circuit that the irst Wave of this cycle of voltage is in a direction tol oppose the voltage of the source normally maintaining the control relay QR energized, thereby causing a momentary reduction in the How of current in the control relay CR. 10 This momentary reduction in the flow of current in this control relay CR causes it to assume its deenergized position; and since it is connected in a stick circuit, it assumes itsA deenergized position permanently until it l5 is restored by some other means.

With the control relay CR deenergized, the repeater relay RR assumes its deenergized position, but theA brake control relay BR is not deenergized because another energizino circuit, including the contacts 48 and 87 of5 the time element device TE, is still intact.

Deenergization of the timing magnet TM of thetime element device TE, as a result f of the deenergization of the repeater. relay RR, causes the balance wheel 43 of this time element device and its associated contacts 48 and 49 to start on their oscillating cycle of operation. After a short arc of move- 3" ment of the time element shaft 42, the contact 49 on this shaft completes a pick up circuit for the control relay CR which may be traced as follows :-beginning at the terminal B of a suitable source of energy, wire 102,- baek contact 110 of the repeater relay RR, Wire 111, contacts 112 and 49 of the time element device TE, Wires 113 and-l 74, secondary coilS of car element- KD, Wire 75, winding of the controlrelay CR, Wire 76 back to the common return wire C. Momentary closure of this circuit energizes the control relay CR which is thereafter maintained energized through its stick circuit heretofore traced. Reenergization of r the control relay CR causes the repeater relay RR to be picked up, whichfagain energizcsthe timing magnet TM. Also, the completion of the circuit for the repeater relay RR through'the front contact 77 of kthe control relay CR furnishes current for the brake control relay BR connected in series therewith. During the time that the contacts 49 and 112 of the time element device close a `ickup circuit for the control f relay CR W ich in turn energizes the repeater relay RR, the brake control relay BR is maintained energized thro-ugh the contacts 48 and 87 of the time `element device TE. The time element device continues to rotate in a counterclockwisel direction .until it .reaches its other dotted position. as shown, andthen' againj'rcturns practically to its initial position, from `whence it is attra'. ted to its normal position by the timing magnet TM acting on the armature 44. It is asrelation with suined that the train is running slow enough so that the time element device has reached its normal position after performing the cycle of operation just explained beforev the car element KD gets into coiiimunicaling the second track clement of this first pair of -trackway devices. When the car element KD passes over this second .track element, having its coil 11 open-circuited, the same cycle of operation takes place, no brake application being effected because the time element device returns to its normal position Without the reception of an intervening knock-down control influenc'e.

Briefly reviewing this c 'cle of operation, it should be remembered tiat the brake control relay BR is maintained energized by the time element device during the time that this time element device agairr picks up the control relay CR and the repeater relay RR, after which the brake control relay BR is lmaintained. energized by the control relay CR but is not independently maintained energized by the time element TE as it is uncontrol influence is received while the time element device is performing its cycle and the contact 48 is not in contacting relation with the contact 87, the reception ofa control influence causes deenervization of the brake control relay BR and interruption of dernormal conditions, so that, if a second its stick circuit permanently. There is, however, still another Way of maintaining the brake control relay BR energized which is efective if the'danger relay DR is deenergized under predetermined limited speeds as more clearly described hereinafter.

(laut/0n condition (speed excessive).- Let us assume that the train continues' to move through the block I while this block is in the caution condition, and that it passes by the second pair of elements at excessive speed. As the car element KD passes over t e first track element of the second pair the time element device TE is again initiated. This time element device again picks up the control relay CR and is still in motion at some point at which contacts 48 and 87 are ont of contacting relation when the car element KD passes over the second element of this pair. -The reception of a control influence by the'contifol relay CR at this time causes deenergization of the brake control relay BR as well as deenergization of the repeater relay RR, this, for the reason that no current can now flow. through the circuit including resistance unit 89, so that thc brake control relay BR assumes its (leencrgizcd position. lVith the brake control relay BR deenergzed, the energizingcircuit Reset from, ground (permitting a s eed of. beginning at theterminal B wire 60, con-A mz'lespcr ww',.0nZy).-In order t at the engmeer may continue to move the train alon thettrackway after an automatic brake application has taken place, he is required lto alight and operate the resetting valve 59 which is onlyaccessible from the ground. If the engineer loperates this valve air pressure is admitted into thecylinder 55, thereby causing the rack 47 and associated contacts 67 to move. to the left or'dotted position. Movement of the rack to such position causes the balance wheel 413 -when'in its un-" biased 'condition with respect to the pinion 46 to assume the same' position as when this wheel is in its normal position asshown in the drawings, so that with the timing magnet TM energized it may again hold the' armature 44 against the residual pin v51,. It.

should be noted that the return of the balance' wheel 43 vto its normal position causes may be traced as follows z-b'eginning at the terminal B, wire 71, front-contact 77 of the control relay CR, Wire 78, winding of the repeater relay RR,.wires 7 9,- 80, and .81, winding of the brake control relay BR,- wires 82' and 116, contacts 67, wire 117, back to common return wire C. This relayA BR after being picked up is again stuck up through its stick circuit heretofore mentioned.

After the engineer had held the resetting or the restoring valve 59 into its active position for a short period he may again return it to its normal position, thereby releasing pressure from the cylinder and 'allowing the spring 57 to return the piston 56. When the contact disk 67 reaches its normal position, the brake control device EPV is again energized which allows the engineer to remove vthe brakes by recharging the brake pipe and proceed along the trackway. It should be noted that the energizing stick circuit for the `lower winding of the danger relay DR was interrupted during thetime that the brake control relay vBR assumed its deenergized position,l by reason of the contact 100 of the brake control relay BR. Since the danger relay DR was energized througha stick circuit, it assumes its deener- ,gizedposition until againrestored by suitable other means. With the danger relay DRl in its deenergized position, and the brake control relay BR again energized as a result of. manual operation of the valve 59and the inflction of the l-penalty associated therewith, the train is again permitted to proceed at a continuing limited speedv of, say, 2Q

miles per hout-bv reason of energization of vtact 61 of the danger relay DR, Wire 119,

contacts 37 and 36 of the speed-governor G, wires 120 and 63, contacts 64 ot' the brake control relay BR, wire 65, winding of the EPV, wire l66, contacts 67, wire 68, primary coil P, wire 69, back tothe common return wire C, the contacts 36 and 37.0nly being in contactingrelation at speeds below 20 miles per hour. i

If the train at any time under this condition of the apparatus assumes a speed greater than 20 miles per hour, the brake control device EPV is deenergized, but is again energlzed as soon as the speed comes below ,this value, so that the engineer may remove the brakes by charging the brake lpipe inthe usual manner "as soon as the train speed is below this value. f.

Automatic reset-Let us assume that traiic conditions ahead have cleared up and that the track relay 4.- assumes its energized position and completes a circuit including the coils 11c and 15 of the restoring trackway elements, and that the train is just passing over these devices so that one of these track elements is in cooperation with the knock-down element KD and the other track element is in cooperation with the restoring car 'element RS. As the train moves by these track'elements forming transformer portions, the element KD by reason of' the strong magnetic field produced by the primary coil P, induces a current in the circuit including the tWo coils 11c and 15v thereby producing an alternating ux emanating from the pole pieces 14 ofthe core 13. A large part of this alternating uX passes throu h the core 23 of the restoring car element tS and induces a similar single cycle of alternating current inthe coils 25 of this restoring car element RS and in the upper. winding of the danger yrelay DR, so that this danger relay DR assumes its energized osition momentarily. With the danger reay DR momentarily energized its stick cirles cuit through the lower win'ding'of this relay is again completed, thereby permanently i.

restoring it to its normal p osltion. With\l the danger relay DR again-energized, the

train may proceedv at a speed dependent on tratlic conditions ahead and the spacing of active pairs of ltrack elements.

the time element device TE is again initiated upon its cycle of operation. Since the speed, as has been assumed, is excessive a second impulse is received by the last element of this pair before the time element device TE causes closure of the contacts 48 and 87.

Deenergization of the control vrelay CR and repeater relay RR, however, does not deenergize the brake control relay BR becauser this relay BR iss-maintained energized through the following circuit-beginning at the terminal B, wire 60, back'contact 122 of the danger relay DR, wire 123, resistance unit 124:, Wires 125 and 8l, Winding of the brake control relay BR, wires 82 and 83, front contact 84: of the relay BR,lwire 85, back to common return AWire C, so that this brake control relay BR is maintained energized entirely independently of the time element device- TE and the lrelays CR and RR controlling the same. The resistance unit 124 as well as the resistance unit 89 have a resistance substantially equal to theresistance of the relay RR, so that the relay BR may be held up by current flowing in any one of the three circuits for this relay which have been traced.

The engineer, by pressing the acknowledging push button 97, has not only prevented the iiiiction of a penalty, but has also prevented an automatic brake application since the train is moving at less than 20 miles per hour, as has been assumed, and the contacts 36-37 are closed. It is thus noted that the engineer is encouraged to operate.`

the acknowledging push button 97 if he is traveling at a speedless than 20 miles per hour, because such operation will prevent an automatic brake application as well as the penalty associated therewith to restore the same, and that he will probably operate this acknowledging button each time he passes a pair of track elements spaced to enforce a speed of .less than 20 miles ler hour. The operation of this acknowledging push button will of course set up a continuing speed limit heretofore fixed at 20 miles per hour imposed by the governor G which will persist until an automatic restoring control influence has been received from the trackway, so that the train in entering a. danger block will be restricted to this speed until 1t passes" trackway restoring apparatus such asl the trackway' devices having'coils 11c and 15, as shown. Further, by this arrangement, since it is very difficult for the engineer to ascertain whether or not he is running his train at less than three miles per hour, the speed limit set iip by the last pair of track elements in the block,\vlien he is actually ruiming at less than this speed, he will be encouraged to operate the lacknowledging push button 97 to avoid the penalty heretofore mentioned, and in so doing will -set up a continuing permissive speed limit.

Clear my'c conditions-Let us now assume that the car-carried apparatus is' 1n its normal condition on a train passing through a block, such as the block I, underclear traffic conditions ahead, and at, a speed in excess of the speed for wliich'the track elements of a pair in the block are spaced. As the car-carried element KD passes over the first element of such a pair the time ele- .ment device is initiated upon its cycle of operation as heretofore described. If this elementl passes over the second element of this first pair the time element device will of course not et have returned to its normal position, it li ving been assumed' that the speed lof the train is in excess of that enforced by this pair of elements. This` is, however, immaterial, since no control influence is transmitted from this second track element, because' the core of this element has its coil 11 closed in a circuit of lowv resistance. One theory by which the failure of transmission of a control influence under these conditions may be accounted for is, that the passage of a few lines of flux through the track element causes a current to be set up in the coil 11 which is in a direction to oppose further increase of flux through this element, so that very little flux is permitted to pass through this track element by reason of the'bucking action of the current roduced by it, and consequently very little fluxis diverted from leakage paths through the secondary coil S. With very little change of flux through the secondary coil only a slight voltage is induced therein and a correspondingly s mall change of current flow takes place in the control relay CR. Inother words, the coil 11 on the track element acts as a bucking coil, so to speak, and prevents to a large extent the passage of flux through the track element, so that no control influence is transmitted by a track element having its coil closed in a deenergized circuit of low resistance'.

Automatic reset at nteimwdiate points in bZ'occf-It may very well happen that a danger block changes to a caution or a clear block shortly after a train has entered such block, and in order to provide means for restoring the car-carried apparatus at an intermediateV- point, trackway restoring apparatus has been shown in Fig. 2 of the drawings located at such point in a'blofck for restoring the car apparatus providing this block is not occupied by another train ahead. p v

In order to ascertain whether there is a train in the saine block in advance of the train in question itis necessary to determine whether or not there is a flow of current in the track rails directly ahead ot' the train in question, and in order to ascertain such o'w .of curi-ent a series two winding track relay SR has been connected in series with the track rails by placing the two windings 127 and 128 around insulated joints 129 in the track rails 1. rlhis series track relay SR is provided with a iront contact 130 which connects the windings of two restoring track elements T in series. It will thus be noted that if there is no train ahead of the train in question inthe same block that this re-r lay SB; will assume its energized position and transmit a restoring control influence to car-carried apparatus such as shown in Fig. 1. l' I Modified form automatic reset-In Fig. 3 has been illustrated the automatic restoring portion of car-carried apparatus such as shown in Fig. 1. Those parts of the car-carried apparatus shown which are also shown in Fig. 1 have been assigned the same reference characters. This restoring apparatus is not traihc controlled and is always edeca primary coil PB and a secondary coil S`a` which are designed substantially the saine4 as are the coils of the knock-down element KD. An alternating current is induced iny this secondary coil Sa similar to a single cycle of alternating current by reason Vsot the passage ofthis car element over an 'efrv fectivetrack element such astheelemeiit 132 for reasons explained in connection with the operation of the element KD when passing over an active track element. This induced current flows through the upper winding of the danger relay DR to restore this relay in a manner already explained.

`The car-carried apparatus ofthis modi- `tied system is the same as that shown in Fig 1, except that the lcar elements provided -are of substantially identical construction the right hand one of which controls the control relay CR and the left hand one of which in the arrangement'shown is always active.

The proper control of the train asit enters the next block is however assured by reason of the active track elements of. the

right side of the track under danger trai'ic.

conditions of the next block, so` that the train after being released will immediately be restricted under danger tratlic conditions.

00ncZuaz'0a.-A train control system has thus been proposed in which speed limits are enforced in a caution block bymechanisin which permits extreme iiexibility in regard to the particular speed restriction enforced at various points in'such block, this flexibility being vfacilitatedfby the employment of the time-distance interval principle of enforcing speed restrictions. The proposed system is one wherein a governor is employed to continually restrict the speed of the tra-in in an occupied `block as a re v sult of thev reception of two successive controlinfiuences in less than a predetermined time previously', and without the reception of an intervening restoring influence. rllie transmission of two such influences is Substantially assured by spaced track elements so close together that the speed ofthe train niust be very low, and probably so -low that the trainis unablev to avoid exceeding it. This system also includes an acknowledging means, whereby the engineer may avoid a penalty but in so doing sets up a permanent restriction `in the movement of his train, which restriction can only be removed by the reception of a control influence from the trackway if traiiic conditions ahead are clear. l

Having thus shown one specific embodiment of the inventionwitli a single modified form of restoring mechanism, it is desired to be understood thatthe Ispecific arrangement shown has been'selected for illustrative purposes rather than with the view of showing the scope'of this invention, and it `'is desired to be understood that various changes and modiiications may be made to adapt the inventionto various types of systems having variouskinds of means for transmittin control influences from the trackway without departing .from the scope ofthe idea of means underlying the `present invention. I v

What I desireto secure by Letters Patent .of the United States is:-h

1. An automatic train control system conn prising, normally inactive means which vwhenr initiated sets up a restricted speed limitv andei'ects an automaticbrake application it this speed limitis exceeded, and means including a device which responds to thev reception of two successive control influences if received in lessl than a predetermined time for initiating said means.

2. In van automatic train control system,

the combination of normally inactive means .for continuously restricting' the speed of a train to a predetermined low speed limit which the train Lcannot exceed without incurring a brake application for controlling thetrain in an occupied block, and apparatus for automatically applying the brakes .responsive to the reception of two successive control inluences in less than a piedetermined time as a resultl of excessive speedy in passing over spacedz'trackway elements 'in a caution block, said rst mentioned means bei'ng initiated if two successive con- `trol influences are received in less than said predetermined timer 3. In an automatic train control system,

the combination o-normally inactive means for. continuously restrict-ing the speed of a train to a predetermined low speed limit which the train lcannot exceedlwithout incurring a brake application for controlling the train in an occupied block, and apparatusA for automatically applying the brakes responsive to the reception of two successive controliniiuences in less than a predetermined timei'as aresult of excessive speed in passing over s aced trackway elements, said means 'y being initiated if two successive control in'- iiuences are received in less than said predetermined time, and means for restoring' Said, :apparatus to normal.

4. In an automatic train `control system,

the combination of normally inactive means for continuously restrictin the speed of a train to a predetermined glow speed limit which `the train cannot exceed without incurringl a brake application for'controlling the trtiin in an occupied block, apparatus for automatically applying thebrakes responsive to the reception of-two successive 'control inuences in less thanV a predetermined time as a result of excessive speed in pass-lv ingover spaced trackway elements, and automatic means controlledv by influencesreceived from the trackway under clear tratlic lconditions/ahead for restoring said means to normal. l 7

5. In an automatic trai@ .control system, the combination of a device for controlling atrain by the time-distance interval principle ina caution block and by a continuing restricted speed limit in an occupied block comprising, a brake control device which if d eenergized applies the brakes of the usual air brake system, means for deenergizing said device by control influences transmitted 'from the trackway as a result of'passing over a pair of spaced trackway devices in less than a predetermined interval of' time, and meansinitiated upon the reception of two control' influences in less than a predetermined time for continuously restricting'the speed of the train to a certain value.

i 6. In an' automatic train control system, the combination of a track divided into blocks in the usual manner, pairs of spaced trackelements in each block for transmit' ting control influences to a passing vehicle,

a brake control device on the vehicle, a caution speedrestricting apparatus for actuating said brake control device if two successive contnol influences are received in less .than a predetermined time, a danger speed thereafter continuing to restrict the speed of`the train to'alow limiting speed until a clearing control infiuence is received from the trackway if the speed of the train is excessive as'evidencedby the transmission of two successive controll influences in less than a predetermined time, and means accessible o'n y from the ground which ir'y actuated restores said brake control device but does not remove the .continuing restrictive speed limit.'

8. An automatic train -control system comprising, trackway apparatus including x spacedftrackway devices having their space' ing ixcd to correspond to speed limits at corresponding points and adaptedkto transmit control influences tothe train when the v'next block in advance is occupied, and carcarried apparatus including, a brake control device, means for deenergizing said device if two successive control influences are received in less'than a predetermined timel another means also initiated if two control influences arereceived in less than a predetermined time which if initiated requires the train to remain below a certain low speed limit toy avoid an automatic brake application, means only accessible from the ground for, restoring said first mentioned means to normal,

and means for restoring said another means to normal comprising, means partly on'tlie vehicle and partly along the track and adapted to transmit a restoring control influence providing traticconditions ahead are clear.

An automatic train control system-comprising, trackway apparatus including spaced trackway devices at points along the trackway having their spacing fixed to cor storing said normally inactive means to normal.

16. An automatic train control system comprising, apparatus partly on the vehicle and partly along the trackway for transmitting control influences from the trackway to the vehicle through an intervening air-gap 'by inducinga potential in a car-carried coil due to movement of the vehicle by a track- Way device and by which insufficient potential is induced to transmit such control influenceif the speed of the vehicle is extremely low, normally inactive means rendered active upon the reception of a control influence and which if active restricts the speedof the vehicle by causing an automatic application of the brakes of the vehicle if the speed'of the vehicle exceeds a predetermined speed limit, means for penalizing the engineer if saidno'rmally inactive means is rendered active by the reception of a-control influence, manually operable acknowledging means which if operated before said normally inactive means is rendered active renders said normally inactive means active and thereby avoids such penalty, and means effective upon the reception of a restoring influence from the trackway for restoring said normally inactive means to normal.

17. An automatic train control system comprising, apparatus partly on the vehicle'and partlyl along the trackway for, transmitting control influences from the trackway to the vehicle through an intervening airgap by inducing a potential in a car-carried coil due to movement of the vehicle by a trackway device andv by which lnsuliicient potential is induced to transmit such control influence if the 'speed of the vehicle is extremely low, normally inactive means rendered active upon the reception ofa control influence and 'which if active re-` structs the speed ofthe vehicle'b causing an automatic application of the lirakes of the vehicle if the speed of the vehicle exceeds a predetermined speed'limit, manually operable acknowled ing means which it operated before said normally inactive means is rendered active renders said normally inactive means active, and means effective upon the reception o-f a restoring influence from the trackway for restoring said normally inactive means toonormal.

18. An automaticl train control system comprising, apparatus partly'on the vehicle and partly a ong the trackway for transmitting control influences fromthe trackway to the vehicle through an intervening air-gap by inducing `a potential in a car.- carried coil due to movement of the'vehicle by .a trackway device and by which insufficient otential` is induced to transmit such contro influence if the s eed of thev vehicle is extremely low, norma ly inactive means rendered active upon the reception of a control influenceanu which if active restricts the speed of the vehicle b causing an automatic application of the lirakes of the vehicle ifvthe speed of the vehicle eX- ceeds a predetermined speed limit, means for penalizing the engineer if said normally inactive means is rendered active by the reception of a control influence, and manually operable acknowledging means lwhich if operated before said normally inactive means is rendered active renders said normally inactive means active and thereby avoids such penalty.

19. An' automatic train control system comprising, apparatus `partly on the vehicle and partly aloner the trackway for transmitF ting control inuences from the trac-kway to the vehicle through an intervening airgap by inducing a `potential in a car-carried coil due to movement of the vehicle by a trackway device and by which insufficient potential is induced to transmit such control influence if the speed rof the vehicle is extremely low, normally inactive means rendered active upon the reception of a control influence and which if active restricts the .speed of theivehicle by causing an automatic application of the brakes of the vehiclel if the speed thereof exceeds a predetermined speed limit, and manually oper- 05 able acknowledging means which if oper# ated before said normally inactive means is rendered active renders said Vnormally inactive means active.

20. An automatic train control system comprising, apparatus artly on theyehicle and partly along tlie track for transmitting control influences from the trackway to the vehicle, a normally inactive device which if active restricts the speed of the vehicle and which is rendered active upon the reception of a control infiuence, means for penalizing the engineer if said device is rendered active by the reception of a control influence, and manually operable means for rendering said device active.

21. in automatic train control system comprising, apparatus partly on the vehicle and partly along the track for transmitting control influences from the trackway to the 1 vehicle, a normally inactive device-which if active restricts the speedl of the vehicle and which is rendered activeupon the reception of a control influence, means for penalizing the engineer if `said device is rendered active and manually operable means effective only if operated prior to the reception of a control influence for rendering the penalizing means ineffective which if operated renders said device active.

22. An automatic train control system comprisingrapparatus partly on the vehicle and partly along the track for transmitting control influences from the trackway to the vehicle. a normally inactive device which if active restricts the speed of the vehicle and which is rendered active uponl the reception of a control influence, means for penalizing the engineer if said device is automatically rendered active, manually'perable means for rendering said device' active,

and means responsive to the reception of4 from the truc-l to normal.

In testimon signature.

vrestoring control nuences transmitted (Way for restoring said device y lwhereof I hereby affix my

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