US1584226A - Train control - Google Patents

Description

w. K. HOWE TRAIN CONIROL Filed Sept. 1.. 1922 2 Sheets-Sheet 1 BY I Q ZZ ATI'ORNEY 2 May 11 1926.

1,584,226 w. K. HOWE TRAIN CONTROL Filed Sept. 1. 1922 2 Sheets-Sheet 2 782mg? R BY I v I TTORNEY Patented May 11, 126.

NETEE s-rice,

W N HBQI" K1 HO E, Q5 R I Et L E Z $03K; A$SIGN B 9 @EN fi-AL BAILWAY- NAL COMPAN 1 G TES, N RK, A QRPOBA QN FNEW YQR A TRAIN C NTR L.

Application filed September This invention relates to automatic train control systems, and more particularly to systems wherein predetermined speed limits are enforced at successive points in a block to bring the train to a stop before entering a danger zone. I In train control systems of the type just referred to the amount of trackwa'y equipment depends largely upon the-nun'iber of control points. Since in this type of system speed limits are only enforced at points along the track, as distinguished from a continued,enforcement of restricted speeds, it is-necessary to restrict the speed at a control point sufiiciently so that the train can be stopped when continuing this restrictive speed, or accelerates to the next fol lowing control point in advance thereof, and so that if the brakes are applied at this following control point the train will be stopped before entering the danger-zone. Under ordinary working conditions, it is often found satisfactory, and likewise economical, to impose a speed restriction at a comparatively few control points only for each braking distance, thereby making the speed limit which must be enforced at each control point to insure safetyconsider-ably than the speed from which the train might be brought to a stop if the brakes were applied at such point. In other words, if only a few control points are employed in each block in this type of system, the speed limits enforced at such control points will in the interests of safety be less than the speeds the engineer might run in making a stop at the signal. Consequently, if the engineer is to regulate his speed so as not to be automatically controlled, he must pass the successive control points at speeds such as would stop his train short of the signal, that is the engineer must aim to stop or shoot, so to speak, at an imaginary sig nal location some distance in the rear of the signal. This is not only confusing to the engineer, but is also contrary to the usual train operating practice.

One of the principal objects and purposes of the present invention is to give the en ineer the usual and proper information 1n 1, 1922, Serial no. 585,676.

regard to the point at which he must attempt to stop the train without impairingthe safety thereof, so that if the engineer fails todo so and the train is stopped at a later point by the automatic equipment, it

will still be brought to a stop before reacha ing the danger one. the present lnvention is to increase the'ca pacity'of railroads employing train control devices which enforce predetermined speed limits at successive control points through bloclrs, by overlapping the control from certain sections of trackway,' thereby permitting closer spacing of mov'ingtrains.

Although the principles underlying the present invention may be applied to type of speed control system, this invention has for convenience been shown in connection with one type of system only, namely, a speed control systememployi-ng the time-distan'ce interval principle, that is, the imposition of a restrictive speed by allowing the train to travel a predetermineddistance in a predetermined period of time as illustrated in the accompanying drawings, in wh'ich:- lEi-gure 1 shows several blocks of the trackway equipment of a train control system embodying the present invention and illustrates speed distance curves, one of which corresponds to the speeds at different points in the block at which if the brahesare applied at a such points the train will be brought to a stop before reaching the entrance to the danger Zone, and the other cor responds to the maximum speeds at which the engineer may operate a train at the severailcontrol points without an automatic brake applicationterminating at the signal location; V i. I

Fig. 2 illustrates in a diagrammatic and simplified manner a portion of the track way equipment illustrated in Fig. 1, and car-carried equipment adapted to cooperate therewith, the several devices beingshown with a View of making iteasy to understand the nature of the invention, 1: ther than the particular construction preferably employed in practice; and

F g. 3 1s anenlarged sectional View of the friction slip clutch shown nrFig. 2.

A further object of In describing the invention in detail, attention is particularly directed to Fig. 1, which shows the trackway devices of a train control system for enforcing successive decreasing predetermined speed limits when cooperating with suitable train-carried devices such as illustrated in Fig. 2. These track devices comprise rails 1 divided into track sections or blocks by insulated joints 2, one block I and the adjacent ends of two other blocks H and J being shown, each of these blocks extending from one insulated joint 2 to the next insulated joint 2 as illustrated. Since the several blocks are the same, like parts thereof will be given the same reference characters with distinctive exponents. These blocks are again divided by insulatedjoints 3 to form a main section provided with the usual track battery 1 and track relay 5, and an auxiliary or overlap section provided with a similar track battery 6 and a track relay 7.

Near the entrance to each block is provided a home relay 8, which is normally energized by the two track relays 5 and 7 of said'block and by the track relay 7 of the block next in advance. The circuit for. energizing this home relay 8 for the block 1 may be traced as follows :-Beginning at the terminal B of a suitable source of energy such as a battery, wire 9 front Contact 10 of track relay 7 wire 11, front contact 12 of track relay 5, wire 13-, front contact let of track relay 7, wire 15, winding of home relay 8, wire 16 back to the common return wire O leading to the other terminal ofsaid source of energy.

Each of the blocks is provided with suitable spaced devices which under caution traffic conditions will communicate control influences to the passing train, the train being provided with suitable cooperating devices and control equipment which will apply the brakes of the train if the train passes two such spaced devices inless than a predetermined time. In the particular embodiment illustrated, these trackway devices comprise pairs of track elements or inductors T and 6, comprising a U-shaped core 17 terminating in enlarged pole pieces 18 (see Fig. 2), the second track element- 25 of each pair being provided with a coil 20 which, under normal clear traffic conditions, is closed in a circuit of low resistance. These track elements are controlled by the home relay 8 of the next block in advance, and since the track elements and their control circuits at the successive control points are the same except for the spacing and location of these elements, they will be given like reference characters with distinctive alpha.- betical exponents. The control circuit for the trackelements t of the block I may be traced as followsz-Beginning at a suitable common return or ground wire C, front contact 23- of the home relay 8 wire 24, coil 20 of track element 6, wire 25 back to the common return wire C, the circuits for the other track elements being the same have their parts designated by like reference characters with distinctive exponents.

In order to limit the speed of a train in entering a block under clear as well as cautiontraffic conditions, an extra element T has been placed at the entrance of each block spaced a suitable distance from the first track element T of the first pair so as to enforce the desired entrance speed, the operation of which will be more sepecifically described in the operation of the present invention. If blocks are encountered in practice which are considerably shorter than the braking distance of a train at high speed or under adverse circumstances, several elements T may be placed in advance of the first pair of track elements T and t and extending into the block in the rear.

Although any type of wayside signals may be employed in connection with the track circuits, and other trackway equipment of the present train control system, light signals of the well-known distinctive color unit type have been illustrated by the green, yellow and red lights G, Y and It respectively. Near the entrance of each block is located a repeater or distant relay D, whichis controlled by the home relay 8 of the next block in advance. Back and front contacts operated by this distant relay D in combination with similar contacts operated by the home relay 8 control the light signals in the usual manner, as is readily apparent from the drawings, the green lamp G being energized when both of these relays are energized to indicate clear, the yellow lamp being energized when the home relay 8 is energized and the distant relay D is de'energized, and the red lamp R being energized when the home relay 8 is deenergized. I

One type of car-carried apparatus adapted to cooperate with the trackway apparatus illustrated in Fig. 1 has been illustrated in Fig. 2, and comprises suitable devices which will first be separately described. One of these devices comprises an influence receiving car element L mounted on the car so as to have a definite and cooperating relation with the track elements T and t heretofore described, this being preferably accomplished by mounting it directly on the truck frame and protecting it from excessive jars and vibration, and from the weather, in any suitable manner. This car element L comprises a U-shaped core 30 terminating in enlarged pole pieces 31, a primary coil P on one of the legs of the U-shaped core, and a secondary coil S on the other leg.

' A control relay and a repeater relay RR are provided which are particularly designed to properly function for the purpose for. which they are intended. Although these relays have been illustrated as identical, this illustration is merely conventional and in practice the control relay is constructed with much smaller moving parts and controls smaller contacts than does the repeater relay RB, and will therefore be more sensitive and function on a smaller change of energy. Both of these relays C and RR have their moving parts Well balanced so that theywill not be materially affected by jars and vibration, and are pref erably mounted in a comparatively heavy spring supported relay casing, which may be provided'with a glass panel and locked or sealed in any suitable manner.

The car-carried devices also include a train control device K, which has been illustrated as an electro-pneumatic valve. This train control crevice K may control the train in any suitable manner as, for instance, by venting the brake pipe when its Winding 32 is deenergized. This device K is of the normall t ener 'ized t We and is normall I enerv a l 7 ift 58d through a stick circuit completed through the front contact 33 controlled by the armature of its electro-magnet. Consequently, a momentary deenergization of the train control device K by deenergization of its. winding 32 Will permanently deenergize it because its energizing circuit Will have been interrupted at its front contact 38.

The car. apparatus further includes a timecontrol device generally designated by TC. This time-control device TC is provided to normally close an auxiliary circuit to open this circuit for a very short period of time after this device has been initiated, to maintain this circuit open for a predetermined time and then again close said auxiliary circuit. This time-control device TC comprises a motor M, having an arn'iature provided with a conjunutator E l, brushes 35, a shunt held Winding 36, and a suitable source of energy illustrated by a battery 87 connected cross the brushes and shunt Winding so as to perx-nanently operatethe motor at a substantially constant speed. This motor is preferably one thatvill maintain a constant speed irrespective of a slight variation in the voltage of the battery 37 and regardless of a slight change in load applied thereto. This operating; characteristic may be obtained to a large extent by proper design and if desired, a suitable speed control regulator may be incorporated therewith to give this mot-or a constant speed characteristic.

The motor M throngs the shaft 38, friction slip clutch 39, shaft 410 and Worm 4:1 drive the worm \vheel 4+2, provided this WOllIl wheel 42 is free to rotate. The construction of the friction clutch 39 is such that it will slip and allow rotation of the motor M without rotation of the worm Wheel 42 without undue heating of this clutch, thus allowing a predetermined torque to be applied to the shaft l0, and comprises two clutch members 39 and respectively Which are urged into frictional engagement by a spring 28. The Worm Wheel 42 has fastened thereto but insulated therefrom a contact arm l3, which is connected to one terminal B of a suitable source of energy, such as a battery. As the Worm wheel'lil is rotated in the direction of the arrow by the motor" tionedwvill sufice the specific device illustrated merely being shown to represent con-' vontionally time-control device having these operating characteristics;

()peroti0n.-Assu1ne that the car-carried apparatus illustrated in Fig. 2 is in its normal conditiom'that is is moving between control points in a block when the next block in advance and the overlap section of the following block areclear. Under these conditions, the control relay C is energized through a circuit TvlllCll'llilily be traced as follows :Beginning at the terminalB of .1 battery which has its other terminal con rected to a common return Wire N Wire 50, front contact 51 of the control relay C, Wires 52 and 53, Winding; of the control relay C, Wire 541i, secondary coil El, Wire 55 back to the common return Wire N.

lVith the control relay C in its energized position, a circuit will be completed for en ergizing the secondary or repeater relay 11R, through a circuit vvoich may be traced as-folloWs:Beginning at the terminal 1% of a battery, Wire 50, front contact 56 of the control relay C, Wire 5'11", winding of the repeater relay Wire 58 back to the commen return Wire N.

The energization of the repeater relay RR closes front contact COi'lllfllGtlllg the energizing circuit for the time-starting magnet (5%, which may be traced follows: Beginning at the terminal ll of a battery,-Wire 6th front contact 61, movable contact 62 and front contact 63 of the repeater relay ER, Will} 64, Winding; of the time-startingmagnet CS, Wire GSback to the common return Wire N.

Another circuit. namely, the main energip inp; circuit for the train control device K, is also energized when the repeater relay HR is in its energized position, and may be traced as follows :Beginning at the tenniiial B of a battery, wire 60, front contact 61 and movable contact 62 of the repeater relay RR, wires 66 and 67, front contact 33 of the time-control device K, wires 68 and 69, winding 32 of the train control device K, wire 70, primary coil P of the car element L. wire wire N.

An auxiliary circuit for energizing the train control device K may be traced as follows :-Beginning at the terminal B of a battery, Wire 72, contact arm 43, stationary contact 7 3, wire 74, release switch 75, wire 67, front contact 33 of the train control device K, wires 68 and 69, winding 32 of the train control device K, wire 70, primary coil P of the car element L. wire 71 back to the common return wire N.

The energization of the primary coil P produces a magneto-motive-force in the core of the car element L which greatly predominates the magneto-motive-force produced by the secondary coil S connected in the energiz- 71 back to the common return ing circuit of the control relay 0. This is due to the fact that the current flowing through the control relay C is very small, that is, is just sufficient to maintain it in its energized position. The magneto-motive-force pro- 'duced by the primary and secondary coils, although being in the same direction, produce very little flux linking both of these coils, this being due to the large air gap between the pole pieces 31.

With the car apparatus in its normal condition as just described, let us assume that the train is entering the block I (see Fig. 1) under clear traffic conditions. As the car element L passes over the track element T, the reluctance through the magnetic circuit including the core 80 of the car element L is momentarily reduced. This change in reluctance causes a sudden increase of flux and then a decrease to its normal condition, this change of flux being partly due to diversion of flux from leakage paths, and partly due to an increase in the total flux through the primary coil P. This sudden increase and decrease of flux through the secondary coil S induces a voltage therein similar to that of a single cycle of alternating current E. M. F. The secondary winding S is so connect-. ed with respect to the battery included in this circuit that the first wave of the unicycle of E. M. F. opposes that of the battery, thereby reducing the energizing current of the control relay C to an extent to drop its arma ture by the action of the spring 76. Since the control relay C is connected in a stick circuit, it will be permanently deenergized until picked up by some other means.

The control relay C having been deenergized. interrupts the energizing circuit for the repeater relay RR, thus causing its armature to drop by the action of the spring 7 7 thereby interrupting one of the circuits for energizing the train control device K heretofore traced. The other of said circuits, namely, the auxiliary circuit, being completed through the contact arm 43 is, how ever, intact and therefore the train control device K will not be deenergized. The deenergization of the repeaterrelay RR closes a pick-up circuit for the control relay 0, which may be traced as follows :Starting at the terminal B of a battery, wire 72, contact arm 43, stationary contact 73, wire 74, release switch 7 5, wire 66, movable contact 62 of the repeater relay RR, back contact 78, wires 79 and 53, winding of the control relay C, wire 54, secondary coil S, wire 55 back to the common return wire N. This causes the control relay C. to be again energized, causing it to complete the previous energizing circuit including its own front contact as heretofore traced, thereby again energizing repeater relay RR.

This momentary deenergization of the repeater relay RR. as just explained, interrupts the normally energized circuit of the time-starting magnet GS, thereby causing the dog 44 to release the contact arm 43, thus permitting the arm 43 to start on its cycle of rotation. The several parts of the timecontro1 device are so designed and con structed that the auxiliary energizing circuit for the train control device K, which is carried through the contact arm 43, will not be interrupted until the epeater relay RP has again been energized to complete the other or main circuit for the train control device K, and consequently the train control device K will not be affected when passing over a single element.

Let us assume that the train is moving at a speed less than the permissive entrance speed of a block, that is, the speed is low enough to allow the contact arm 43 to complete its travel of one revolution, and again to be stopped by the dog 44 during the time the train travels from the track element T to the track element T. If now the track element 6 is passed over, the same cycle of operation will take place as just explained, without in any way affecting the train'control device K. i

Let us assume now that the train is exceeding the permissive entrance speed, and reaches the track element T before suiiicieut time has been allowed for the contact arm 43 to again reach its stationary contact 73. The control relay C will again be deenergized in the same manner as heretofore described, thereby deenergizing the repeater relay RR. Bearing in mind that the contact arm 4-3 is on its cycle of rotation and has not yet reached its stationary contact 73, and therefore that the auxiliary circuit is now interrupted, the deenergization of the repeater relay RR will momentarily deener- Gil gize the train control. device K. Since the train control device K is connected in a stick circuit including the front contact 33 thereof, a momentary deenergization of the train control device K will permanently'deenergize it, thereby applying the brakes. The pick-up circuit for the control relay C will not be closed due to the making of the baclr contact 78, because there is no source of energy connected to the movable contact 62, this energy having been received from the contact arm 48 under previous conditions. l Vhcn the contact arm 4E3 reaches the sta tionary contact 73, the pick-up circuit for the control relay C heretofore traced will be completed, thus causing it to pick up and c again energlze the repeater relay RE. The energization of the repeaterrelay RR closes the circuit for the time-starting magnet G5 to again move the armature 45 against the stop 80, thereby stopping the contact arm 4:8

when it has completed its cycle of rotation.

The train control device K having been deenergized, as just explained, causes the train to come to a stop automatically. In order to again proceed, it is necessary for the engineer to operate the release switch 75. This release switch may be contained in a locked box, the key of which is held-by some other person, such as the conductor, so that a certain amount of publicity is connected with such automatic brake application; or it may be accessible only from the ground so that it is necessary for the engineer to wait at least until the train has been brought to a stop before this release switch 75 can be operated. The circuit for energizing the winding 32 of the train control device K, by operating the release switch 75 after an automatic brake application has occurred, as just explained, may be traced as follows: --Beginning at the terminal B of a battery, wire 60, front contact 61, movable contact 62 of the repeater relay RR, wire 66, release switch 75, wires 81 and 69, winding 32 of the train control device K, wire 70, primary coil P, wire 71 back to the common return wire N. The train control device K having new again been energized through its energizing circuit heretofore traced, including its stickup contact 33, allows the train to proceed under the control of the engineer.

It should be observed that this train control device is of such a character that when two successive control influences are received in. less than a predetermined time (the time required for the contact arm 43 J0 make one revolution), the train control device K will be actuated. Therefore, it is possible to limit the speed of the train to any desired. value by spacing the track elements a distance which the train may travel at the speed in questicn d' ng" :lltli time set off by the t me control device TL; The 0 ion of the aurora: hrelze contain therefore, dependent upon the average speed of the train between tvvo successive track elements. The time-interval allowed by the time control device TC is preferably ,comparatively short, so that the track elements will be spaced relatively close together, thus making the average speed approximate the actual speed when going over the second track element of such a pair.

Having now considered the entranceof a train into a clear block, both When the speed is less and more than the permissive entrance speed, let us consider the. movement of a train into the block I under clear traf fie conditions at a speed lower than the: permissive entrance speed into the block I but higher thanthe permissive speed allowed under caution traliic conditions by the track elements T and t. Asnthe train passes by the track element T, the time-control device will be initiated upon its cycle of operation, thereby opening the auxiliary circuit for the train control device K. for a predetermined interval of time, as heretofore explained. As the car element L now pass-es over the next track element 6, the train control device K will not be deenergized even though the auxiliary circuit thereof is open at this time. This is accounted for by reason that the passage of the car element L over the track element having its coil closed in a circuit of low resistance, causesv very little change of flux throughthe secondary coil S of the car element L. One theory of operation which accounts for such slight change of flux in the car element is that a slight change of flux through the track element i induces a comparatively large cur rent in the coil 20, which at this time is closedin a circuit of low resistance, this current being in a direction to oppose the flux producing it and therefore prevents further pass-rage of flux through the track element. This slight change of flux through the track el ment t likewise causes only a slight change of flux through the secondary coil S of the car element L, which is insufficient to induce enough voltage to deenergi ze the control relay C, and therefore the repeater relay RR will be maintained energized and the brakes will not be applied even though the train exceeds the permissive speed allowed by these elements T and t Vith the block I under caution traflic conditions, the home relay 8 of the block J will be deeuergized because one of the s ections of thenext block in advance or the overlap section of the following blocl: areoccupied by a train, or are in danger for some other reason, which causes the track relay of the particular se drop its armature, tlj' signa ing circuit forfil df With ction occupied to y opening the cu ho e relay '8 here in; home r'elav' Q ar tiac'i; elements i: will lea be open-circuited, and therefore will affect the car-carried apparatus of the passing train in the same manner as the track elements T and T, as heretofore explained.

\Vith the train moving in a caution block at a speed higher than that enforced by the track elements T and t, the passage of the car element L over the track element T will start the time-control device upon its usual cycle of operation, as heretofore explained. As the car element L now passes over the next succeeding track element t, insuflic-i-ent time having been allowed for the contact arn'rtS to reach the stationary contact 73, the passage of the car element over the track element 25 will deenergize the control relay C and repeater relay RR respectively, thereby deenergizing the train control device K because the auxiliary circuit for this device is still open atthe contacts 4i373 of the time-control device TO. The brakes will, therefore, be applied to bring the train to a stop as heretofore explained, the eugineer being required to operate the release switch in order to again proceed. Under caution traffic conditions, a predetermined speed will be enforced at each of the succeeding pairs of track elements, such as the track element's and t in the same manner as just explained, in connection with the passage of a train over the track elements T and t, the only difference between these several pairs of track elements residing in their spacing, which decreases as the exit end of the block is approached, thereby enforcing gradually decreasing permissive speeds .upon a passing train. I

Various methods may be used to determine the spacing between pairs of track elements, and the control points at which these pairs are to be located as well as the length of the overlap track circuit, as long as this overlap track section is sufficiently large to prevent the train from running therethrough if a brake application is made at any of the control points at the highest speed that the train is apt to have when passing such point. For instance, if the engineer passes a. control point at the entrance of the block at a speed lower than the permissive speed at this point, he would not have a higher speed than this at the following control point unless the train accelerated; and if such acceleration is to be taken into consideration, there is a limited speed above which the train can not get.

In Figure 1 of the drawings has been illustrated one method of determining the location of the various track elements and the length of the overlap track section. In this particular layout, it has been assumed that the engineer will not accelerate his train when running in a caution block. If such acceleration had been taken into consideration, the various control points would prefapplication when it is t aveling at the high est speed it can assume at a preceding control point substantially as shown by the distance 0L laid off in Fig. l of the drawings. From the righthand end of this overlap block, a curve, conveniently called the brake application curve, may be drawn back as illustrated by the dot and dash curve 91, which represents points along the track at which if a brake application is initiated, the train will stop at or before the end of the overlap section. From the entrance to this overlap section, that is, from the point of location of the signal, another curve may be drawn, as illustrated by the solid line 92, which may for convenience be called speed- 'distance brake performance curve and represents the speeds at various points along the trackat which the train is running when, with its brakes applied, it stops at the signal. A low permissive speed having'been determined at which the engineer may pass the signal will then be laid off, as shown by the dotted line 93, representing seven miles per hour in the present arrangement.

The last pair of track elements T and i will be located at a point along the track corresponding to the point where the line 93 crosses the curve 92, in a manner so that a vertical line through this point falls substantially midway between these. track elements. These track elements T and t will be spaced to enforce this low permissive speed of seven miles per hour. A dotted line 94 may then be projected up vertically from. the last track element It, and where this line 94 crosses the brake application curve 91 represents the permissive speed of the next control point in the rear, as shown by the. line 95 representing twenty-one miles per hour. The point midway between the pair of track elements next in the rear namely,

the pair T' and t is determined by the point llti is twentyeight and one-half miles per hour. This same method of locating the points and spacings of the various pairs of track elements may be carried out in any desired number toward the entrance to the block, an additional element T being provided to enforcesu predetermined entrance speed which a tram should not exceed under clear traffic trains of different classes may have their the train and the point at which suitable time-control devices adjusted to set oil different periods of time, thereby causing certain trains to be limited in their speed more than others in a definite ratio for each control point along the track. For instance, let us assume that a freight train has its time element device TC adjusted for two seconds, whereas a passenger train has its time element device adjusted for one second. As these trains pass through a certain block, such as the block I for instance, the freight train will be allowed to run at a speed equal to one-half of the speed at which the passenger train may run at each control point including the permissive entrance speed to the block. 7

If, as shown, the overlap. section for a block is used as part of the braking distance for automatic control for trainsin the succeeding block in advance, or in other words, if the automatic brake controlling distances of the blocks overlap, train movement may be said to be facilitated because of the closer train spacin For example, if the overlap section at the end of block H is used both for safe stopping of trains in block H and also in block I, then the train s )acing has been reduced to this extent.

t is thus seen that the present train control system. allows the engineer to aim to stop at the signal, and at the same time provides a. safe landing place, so to speak, if

he fails to control. his train to stop at such signal. it should be understood that, although the principles underlying the present invention have been shown applied to a system where speeds are enforced tempovmcnt of distance along the block, there isalways a difference between the point at which the engineer may be required to stop automatic apparatus will bring the train to a stop, if the engineer fails to do so; and the provision and arrangement of the track circuits and signals as illustrated in the present embodiment of this invention may be organ ized to adapt them for such a continuous speed enforcement system and improve the traflic carrying capacity of railroads employing the invention.

Other deviations from the specific disclosure will be evident to those skilled in the art, and I desire to have itunderstood that the specific structure shown and described is merely illustrative of the invention, and does not exhaust the various embodiments thereof.

hat I claim as new ant desire to secure by Letters Patent of the United States, is

1. In a. train control system of the type which enforces predetern'iined speed limits at control points in a block by an application of the brakes if the train passes over a predetermined portion of track in less than a predetermined time, of a trackway divided in a small overlap and a large main section having signals at suitable points and provided with trackway devices which permit the engineer to run the train at a speed so that if the brakes are applied the train is brought to a stop at the end of the main section and control devices for controlling said t-rackway devices which permit a train to pass a previous signal at high speed only if the main section provided with said trackway devices and the overlap section in advance thereof, which extends a distance so that the train is unable to pas therethrough if an automatic brake application occur" are clear.

2. In a train control system comprising ca-rcarried equipment which will apply the brakes automatically if two successive control influences are received in less than a predetermined time, and a trackway divided into blocks having an overlap track circuit followed by a main track circuit, track devices in each block adapted to cooperate with the car-carried equipment to apply the brakes if the engineer exeeds a speed which will carry the train beyond the exit end of the block if he makes a service brake appli cation, and means for governing said track- :ay devices controlled jointly by the two track circuits of the block in advance and by the overlap track circuit of the second block in 'advance, said overlap track circuits extending a distance into the block which the train can not overrun when an automatic brake application has been made.

3; In a train control system of the type in which predetermined speed limits are enforced if the train passes two successive track devices in less than a predetermined time, of means for entorcing predetermined speed limits at the entrance to a block rcgardless of trat'fic conditions including a pair of track devices comprising inert masses of iron, and traffic controlled inert trackway devices located at subsequent points along the track for enforcing gradually decreasing speed limits.

4. An automatic train control system comprising, car-carried devices which will apply the brakes if two successive influences are received in less than a predetermined time, and trackway devices comprising a plurality of pairs of track elements adapted to transmit such influences to the car-carried devices under caution traffic conditions, the elements of successive pairs being spaced to set up decreasing speed limits which elements if these speed limits are just exceeded act to apply the brakes and bring the train to a stop at a danger signal; and a safety zone extending beyond said danger signal a distance so that the train will not pass through said zone if it travels past one pair of track elements at a speed enforced at the previous pair of elements and the brakes are applied when passing the last pair of elements, said safety Zone being shorter than liira'king distance for normal clear speed.

5. In an automatic train control system, the combination with car-carried apparatus of the type in which if two successive con trol influences are received from the track way in less than a predetermined period of time the brakes are applied, of trackway means comprising blocks divided into an overlap section and a main section, trackway devices in the main section of said block adapted to cooperate with said car-carried devices permitting the train to travel at a speed so that if the brakes are applied it will be brought to a stop at the end of the main section of the block without incurring an automatic brake application under caution traffic conditions, the various constants being so chosen that if the engineer exceeds such speed limit the train will be brought to a stop automatically before entering the main section of the block next in advance. said overlap section being shorter than said main section.

6. In an automatic train control system, the combination with car-carried devices, of

a trackway having signals at suitable points and provided with devices which in co operation with suitable devices on the train permit the engineer to run the train at a speed so that if the brakes are applied the train will come to a stop at a point at or in the rear of a signal at danger without the initiation of an automatic brake application, and control devices which permit a train to pass through a block at high speed only if the block in advance and a section of the second block in advance thereof, which extends a distance so that the train is unable to pass therethrough if an automatic brake application occurs in said block, are clear, said section being shorter than braking distance for normal clear speed.

7. In a train control system, the combination with car-carried devices, of a trackway divided into blocks having an overlap track circuit followed by a main track circuit, track devices in each block adapted to cooperate with the car-carried devices to apply the brakes if the engineer exceeds a speed which will carry the train beyond the exit end of the block if he makes a service brake application, and means for governing said trackway devices controlled jointly by the two track circuits of the block in advance and the overlap track circuit of the second block in advance, said overlap track circuits extending a distance into the block which the train can not overrun when an automatic brake application has been made.

8. An automatic train control system of the speed control type, comprising a trackway divided into blocks each having an overlap section followed by a main section, means partly on the vehicle and partly along the trackway for automatically applying the brakes of the vehicle if it exceeds successively lower speed limits in traveling through the block under caution traffic conditions with the next block in advance or the overlap section of the second block in advance occupied by another train, said speed limits being above the speed-distance brake performance curve of a trainentering at the normal running speed and decelerating under a service brake application to stop at the end of the block, the length of the overlap section being so chosen that if the brakes are automatically applied as a result of exceeding any permissive speed limit the train will be brought to a stop in the overlap section of the next succeeding block, said overlap section being shorter than said main section.

9. An automatic train control system 01 the speed control type in which the brakes of the train are automatically applied if the speed of the train exceeds predetermined speed limits depending on the posi tion of the train in a block and tratiic con- (lit-ions ahead comprising, a trackway divided into blocks, an overlap section follower by a main section, means partly on the vehicle and partly along the trackway establishing successive lower speed limits in" step like fashion under caution traiiic conditions when the block in advance or the overlap section of the second block in advance are occupied which permits the engineer to bring histrain to a predetermined low speed at the exit end of the caution block in the usual manner without exceeding such speed limits, said means including means whereby if such speed limits are ex cee'ded the brakes of the train. are automat ically applied and cause the train to be brought to a stop in said overlap section, said overlap section being shorter than said main section.

10. An automatic train control system of the speed controltype in which the brakes of the train are automatically applied if the speed of the train is excessive comprising, a trackway divided into blocks provided with the usual closed track circuit having an overlap section followed by a main section, speed restricting means partly on the train and partly along the trackway for setting up successive decreasing permissive speed limits falling on a speed-distance brake performance curve which reaches the zero speed value at the end of the block, the spacing between changes in successive speed limits and the length of the overlap section being so proportioned that a train passing through a caution block at excessive speed will be brought to a stop by an automatic brake application before it has passed through the overlap portion of the next block in advance, said overlap section being shorter than braking distance for a train running at the permissible speed at the entrance to such cantion block.

11. An automatic train control system of the speed control type in which the brakes of the train are automatically applied if the speed of the train is excessive comprising, a trackway divided into blocks provided with an overlap section followed by a main section each having the usual closed track circuit including a track relay, speed restricting means partly on the track and partly on the train for setting up a plurality of decreasing permissive speed limits at successive points of the main section under caution trafiic conditions when either the block in advance or the overlap section of the second block in advance are occupied consisting of a single speed limit for a certain portion of trackway and for effecting an automatic brake application if such per- ,missive speed limits are exceeded, said speed limits, lengths of track portions and the length of the overlap section being so proportioned that the permissive speed at the entrance end to each track portion is such that if the brakes are applied the train will come to a stop before reaching the end of the main section of the track, and if the brakes are applied at any speed the train may attain in such track portion the train is automatically brought to a stop in the overlap section, said overlap section being as short as possible and which will still assure stoppage of the train within the limits thereof due to an automatic brake application initiated in the preceding block.

12. An automatic train control system ti. speed cl trol type, comprisin a divider; inte blacks clnieist overlap section followed by a main section each provided with the usual closed track circuit and a track relay, means partly on the vehicle and partly along the trackway for automatically applying the brakes of the vehicle if it exceeds successively lower speed limits in traveling through the'block under caution tratlic conditions with the next block in advance or the overlap section of the second block in advance occupied by another train, said speed limits being above the speed distance brake performance curve of a train entering at the normal running speed and decelerating under a service brake application to stop at the end of the block, the length of the overlap section being so chosen that if the brakes are automatically applied as a result of exceeding any permissive speed limit the train will be brought to a stop in the overlap section of the next succeeding block, said overlap section being shorter than said main section.

13. An automatic train control system of the speed control type in which the brakes of the train are automatically applied if the speed. of the train exceeds predetermined. speed limits depending on the position of the train in a block and traffic conditions ahead comprising, a trackway divided into blocks consisting of an overlap section followed by a main section each having the usual closed track circuit including a normally energized relay, means partly on the vehicle and partly along the trackway establishing successive lower speed limits in step like fashion under caution traflic conditions when the block in advance or the overlap section of the second block in advance are occupied which permits the engineer to bring his train to a predetermined low speed at the exit end of the caution block in the usual manner without exceeding such speed limits, said means including means whereby if such speed limits are exceeded the brakes of the train are automatically applied and cause the train to be brought to a stop in said overlap section, said overlap section being shorter than said main section.

14. An automatic train control system of the speed control type in which the brakes of the train are automatically applied if the speed of the train is excessive comprising, a trackway divided into blocks having an overlap section followed by a main section, each provided with the usual closed track circuit including a track relay, speed restricting means partly on the train-and partly along the trackway for setting up successive decreasing permissive speed limits falling on a speed-distance brake performance curve which reaches the Zero speed value at the end of the block when either of the track relays of the sections of the block in advanceo'r the track relay of the overlap section of the a M, and their in advance me tltifllifii Jed, the

spacing between changes in successive speed limits and the length of the overlap section being so proportioned that a train passing through a caution block at excessive speed 5 will be brought to a stop by an automatic brake application before it has passed through the overlap section of the next block in advance, said overlap section being shortor than braking distance for a train running at the permissible speed at the entrance to such caution block.

In testimony whereof I hereby affix my signature.

' WINTHROP K. HOVE.

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