US1551515A

US1551515A - Automatic train control system

Info

Publication number: US1551515A
Authority: US
Publication date: 1925-08-25
Anticipated expiration: 1942-08-25

Description

Aug. 25, 1925. 1,551,515

w. K. HOWE AUTOMATIC TRAIN CONTROL SYSTEM Filed Nov. 12, 1919 4 Sheets-Sheet 1 a T] F E1 1| 311 F-Om Flel

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Aug. 25, 1925. 1,551,515

w. K. HOWE AUTOMATIC TRAIN CONTROL SYSTEM Filed NOV. 12, 1919 4 Sheets-Sheet 2 'IIIIIIIIIII 'l @ATTORNEY.

Aug. 25, I925.

W. K. HOWE AUTOMATIC TRAIN CONTROL SYSTEM 4 Sheets-Sheet 3 Filed Nov. 12, 1919 minim-nun"...-

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1 I BY Z;

' ATTORNEY.

warm- Aug. 25, 1925.

W. K. HOWE AUTOMATIC TRAIN CONTROL SYSTEM 4 Sheets-Sheet 4 Filed NOV. 12, 1919 I VB 0% @h/JTTORNE Y.

M* ET BY To all whom it may concern Patented Aug. 25, 1925.

umrso STATES 1,551,515 PATENT ornca.

WINTHROP K. HOWE, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

AUTOMATIC TRAIN-CONTROL SYSTEM.

Application filed November 12, 1919. Serial No. 881,527.

Be it known that I, WINTHRoP K. Howe, a citizen of the United States, and a resident of the city of Rochester, in the county of Monroe and State of New York, have invented a new and useful Automatic Train- Control System, of which the following is a specification. I

This invention relates to automatic train control systems for railways.

In accordance with this invention, a controlling impulse or influence is transmitted from the track to the train at each caution signal or corresponding control point, and unless the engineer at the same time takes some appropriate action in recognition or acknowledgment of the existence of danger ahead, suitable apparatus'is automatically set into operation which tends to give a service application of the brakes. This apparatus is preferably of such a character that the engineer may prevent or. hold off the service application of the brakes, if he desires, but at the same time provision-is made so that, if the engineer permits this ap aratus to act, he will be subjected to consi erable annoyance, publicity, or the like. The penalt my system imposes upon the enginear or his failure to perform his duties properly, is designed to impress the engineer with his carelessness and negligence at the time, rather than by subsequent punishment or discipline; and since the engineer knows he alone is responsible for the penalty, it is expected that he will be induced to be more careful, rather than attempt to circumvent the train control apparatus in some way.

The means I preferably employ to enable the engineer to pass a caution signal without getting into a difiicult osition, is some form of a simple acknowledging or holdofl" device, which on account of the ease with which it can be manipulated, tends to encourage the engineer to watch for the signals. The en eer however, might maliciously or care essly hold or fasten this holdoff device in the hold-off position, and to obviate this ossibility, my invention includes a cheering or protective appliance which prevents the engineer keeping the hold-oil device in the operated position permanently because in so doing, he will be subjected to the same penalty that the holdoff device is intended to prevent.

Under ordinary circumstances, the engiuser may be relied upon to slow down his train, if he is fully aware of danger ahead, but in order to safeguard the train in case the engineer for any reason fails to make a timel reduction in speed, I also provide suita le means for stopping the train automatically as an emergency measure, if the engineer fails to reduce the speed of his train at the proper time and to the extent required for safety. In this wa the ultimate safety of the train is made oubly certain, since not only must the engineer, assisted by the train control apparatus, fail to perform his duties, but also the train control mechanism must fail, before accident can occur.

My invention also contemplates various modifications and'adaptations of the principles and functions above described. For example, the apparatus may be constructed so that, if the engineer fails to make timely operation of his hold-off device at a caution signal, he is obliged to call for the assistance of the fireman or some one else to relieve him from the annoyance and difficulties resulting from such neglect. Also, the speed regulating features of my system may be emplo ed separately without the apparatus provi ing for automatic control at a caution signal, the indication of the signal itself being relied upon to inform the engineer of the necessity for reducing speed. Further, the speed re ulating features may be employed to en%orce any desired speed limits upon the ap roach to sharp curves, crossovers, draw ridges. and like permanent hazards which require the train to travel by them at a limited speed.

Other objects and features of my improved system of train control will appear hereinafter during the description of the specific embodiments of my invention.

In describing the invention in detail, ref= erence will be made to the accompanying drawings,in which Figure 1 shows in a simplified and diagrammatic manner a portion of a railroad track equipped in accordance with my invention, together with somecurves illustrating the contemplated performance of trains;

Fig. 2 illustrates the car equi ment, together with the trackway impu se device, the parts and circuits in this view being shown more with the view of making the functions and mode of operation easy to "making understand than with the view of showin the precise construction and arrangement 0 parts preferably em loyed in practice.

Fig. 3 is a detai sectional view of the valve forming part of the hold-0R device;

Fig. 4 illustrates a modified construction of the engineers hold-0d device;

Fig. 5 illustrates a modified construction of the car equipment in which the cooperation of the fireman, or some (person other than the engineer, is require to get the engineer out of the difiicult position in which he is laced when he fails to make timely operation of his hold-0E device;

Fig. 6 illustrates a modified construction of a resetting or restoring device;

Fig. 7 illustrates a modification of my system involving the speed regulating features, without the automatic control at the caution signals;

Fig. 8 illustrates how the system may be arranged to enforce two or more difi'erent speed restrictions in a caution block; and

Fi s. 9 and 10 illustrate how any desired spee limits may be enforced upon the approach to a crossover or sharp curve, respectively.

Referring first to Fig. 1 which illustrates the trackway equipment, the track rails 1 of the railroad track are divided by insulated joints 2 into blocks in the usual wa two complete blocks B and C with the a iacent ends of two other blocks A and D aving been shown. For the purpose of illustratin the applicability of my invention to di erent length blocks, the block C is assumed to be longer than the block B. The trackway equipment associated with the various blocks is the same. and for convenience the various parts and circuits will be given like reference characters with distinctive exponents. Each of the blocks is provided with a track battery 3 and a track relay 4, constituting the well known normally closed track circuit. My system of automatic train control is referably used in connection with the usual xed signals of the well known automatic block signal system, and such signals S are illustrated conventionally in Fig. 1 the controlling circuits for such signals being omitted for the sake of simplicity.

Associated with each of the blocks is a cautionary track-way element T, which is located at a distance from the end of the block sufficientto permit autrain, running at its maxium speed, to be stopped in the way ordinarily employed by engineers in a service stop. In cases where the length of the block is substantially the same as this service stopping distance, the cantion trackway element T is located at or adjacent to the entrance of the block. ias exemplified in the case of the block B in Fig. 1. In instances, however, where the blocks are longer than the distance usually required to make a service stop, I prefer to locate the caution trackway element T at the appro riate point inside of the block and beyond t e entrance thereof, as exemplified in case of the block C inFig. 1, although this is optional.

In addition to the cautionary trackw ziy employed in my improved system, but I prefer to employ impulse transmitting means of the inductive t pe and have illustrated one form of suc inductive means. The particular type of trackway element illustrated (see Figs. 1 and 2) comprises a U-shaped core or yoke of magnetic material having enlarged ends constituting pole pieces, and provided with a coil 5. This trackwav element may be located crosswise or lengthwise of the track, between or outside of the track rails, and in practice would be encased and protected against the weather, dragging brake beams and the like. In the arrangement of trackway circuits illustrated, a circuit for the coil 5 of each of the trackway elements of each block is controlled by the front contact of a line relay 6, or 6, the controlling circuit for these line relays being governed by the track relay of the next block in advance. This arrangement is only typical, and is susceptible of change and modification. The essential requisite for my system of train control is that the trackway elements of each block shall be placed in the stopping condition when the next block in advance is occupied, and in the type of impulse transmittmg means illustrated, this is accomplished by opening the circuit for the coils 5 of the several trackway elements by means of line relays.

Referring now to Fig. 2, the car equipment comprises a car-carried element L adapted to be influenced by the trackway elements T, T and T" when these have their coils 5 opencircuited; a hold-ofi' device H, arranged for convenient operation by the engineer and protected so as to prevent the engineer from keeping it in the operated position; a pneumatic device F tending to move the engineers brake valve to the service position, whenever the train passes a trackway element in the stopping controlling condition, and the engineer fails to operate his hold-off device H; and finally, a time controlled apparatus K which, in conjunction with the pair of trackway elements T and T at an intermediate point in a caution block, acts automatically to cause an application of the brakes independently of the engineer, if the speed of the train at said intermediate point 15 above a predetermined minimum. If desired, of course, instead of an emergency application of the brakes a heavy service application may be used; but, in order to carry out the intended operation, I prefer to employ a brake application which is as powerful as it is safe and desirable for the equipment, so as to obtain maximum protection for the train and also impose a real penalty upon the engineer, all as explained hereinafter.

The car-carried element L comprises an inverted U-shaped core or yoke 7 of magnetic material, preferably laminated, which is provided with the usual pole pieces, and is carried by the locomotive or other railway vehicle so as to pass over the trackway elements T, T and T Each leg of the yoke 7 carries a coil designated 8 and 9, respectively. The coil 8, conveniently termed the field coil, is constantly supplied with current from a battery 10, and produces a magneto-motive force tending to send flux through the yoke 7. Also included in circuit with the battery 10 and the coil 8 is a check relay X WlllCl'l, on account of its operating characteristics hereinafter explained, serves to detect an interruption or cross in this circuit. The secondary coil 9 is connected in circuit with a control relay R and a small battery 11. The detail features of construction of the oar-carried and trackway elements form no part of my present invention, and are merely illustrative of a type of inductive impulse transmitting means which may be employed in my improved system.

Both of the relays R and X are preferably of the balanced type so as to be responsive to either an increase or decrease in the normal current for which the relay is adjusted. In the simplified construction illustrated, the armature 12 of the relay is biased by a spring 13, and is provided with an insulated striking piece 14. This striking piece 14 is positioned between two resilient contact springs 1515 which normally press against two electrically connected and fixed contacts 16 desi nated conventionally by arrows. The spring 13 is adjusted so that, with the normal current flowing in the winding of the relay, its armature 12 is balanced. If this normal current is increased, the attraction of the armature 12 overcomes the spring 13, and the striking piece 14 moves contact spring 15 out of contact with its coo crating contact 16. On the other hand, i the normal current is decreased, the spring 13 overbalances the armature 12 and causes separation of contact spring 15 from its cooperating contact 16. The circuit controlled by the relays R and X is carried through the contact springs 15 and 15 and shown in Fig. 2;

the fixed contacts 16, so that this circuit is opened whenever the current normally flowin through these relays is either increase or decreased.

The engineers hold-oil device H shown in Fig. 2 comprises a casing 17 in which the several parts are enclosed for protection and also to prevent unauthorized interference, this casing being in practice provided in the usual manner with a suitable sealed or locked door or cover (not shown) which permits access to the interior by authorized persons for inspection and maintenance. Within the casing is a rotary valve V. A lever 18 is fastened to the stem of the valve V and projects out of the casing throu h a slot 19. This lever 18 is preferably provided with a suitable handle for facilitating its manual operation, and also a latch 18' of suitable construction (illustrated in a simplified and conventional manner) which is adapted to cooperate with a notch in a curved ridge or sector 20 integral with the casing. This sector 20 is provided with a shoulder 21 near one end constituting a stop for the lever 18 in its operated or hold-off osition. The other end of the lever 18 carries an insulated contact block 22 which is adapted to bridge a pair of stationary contacts 23 (shown conventionally as arrows) when the lever is shifted to its operated or hold-off position, as partially shown in dotted lines. Compressed air is supplied to the valve V from the main reservolr, or other source of pressure, through a pipe 24; and when the lever 18 is moved to its operated position,the valve V is shifted so as to open communication from the pipe 24 through passage 25 and recess 26 in the valve (see Flg. 3) to a pipe 27. Pipe 27 communicates through an adjustable restricted orifice 28 (illustrated conventionally) to a small reservoir 29; and this reservoir 29 is in turn connected by pipe 30 with a cylinder 31. An air-tight piston 32 in the cylinder 31 is urged by a compression spring 33 to the left hand position as and its piston rod 34 carries a head 35 of insulating material, which engages a contact (spring 36 when said piston rod is projects thereby separating said contact spring from its cooperating contact 37, shown conventionally as an arrow. With the lever 18 in its normal pos1- tion, as shown, cylinder 31 and reservoir 29 are exhausted to atmosphere through recess 26, passage 25 and port 38 (see Fig. 3).

The apparatus for giving an automatic application of the brakes when the engineer fails to operate his hold-off lever 18. pro viding the engineer doesnot oppose such automatic application, may ta e various forms. In the construction illustrated in Fig. 2, I provide a pneumatic device F which is coupled to the engineers brake valve and which acts, when set into operation, to exert a strong pressure tendi to shift the brake valve to the service position, this pressure, however, being small enough to enable the engineer to hold his brake valve against movement by some exertion, and being continued for such a length of time that the difiiculty in holding the brake valve against movement would become objectionable and obnoxious to the engineer. The engineers brake valve E and its usual operatin handle 40 are illustrated conventionally. sector 41 is fastened to the stem or shaft of the brake valve E in a suitable manner so that as the sectorv 41 is swung, the brake valve will be shifted to apply the brakes. The sector 41 meshes with a rack 42, which is integral with or connected to a rod 43. The rod 43 asses through one end of an operating cy inder .44, and loosely through a piston 45 in said cylinder, the end portion of said rod 43 bein screw-threaded and provided with two adjustable clamping nuts 46 against which the piston strikes when moved to the right, as viewed in Fig. 2. Stops 47 fastened to the cylinder 44 limit the righthand movement of the piston 45; and by adjusting the nuts 46, this limited movement of the piston 45 may be employed to shift the engineers brake valve accurately to the service position, or if desired, to an emergency position. The rod 43, since it slides loosely through the iston 45, does not prevent the engineer moving his brake valve handle 40 to any position he desires while running his train in the ordinary way.

Fluid pressure from the main reservoir or the like is automatically supplied to the cylinder 44 on the lefthand side of the piston 45 (as viewed in Fig. 2) through a pipe 48, when an eleotropneumatic valve E. P. V. is deenergized; and this pressure may escape to atmosphere gradually through a pipe 49 and an adjusta le restricted orifice 50. An air whistle 51 may be attached to the pi e 49 so that the escapin air will scan the whistle and give pub icity to the fact that the engineer has been negligent. Such a whistle, while not BHSSQILtlfll part of my pro osed system, is desirable because it intr uces an element of publicity in connection with ne lect of the engineer, which with some indivifuals is often more of a penalty than the trouble and annoyance of holding the brake handle. 0

Various types of electropneumatic valves may be employed to supply pressure to the cylinder 44. In the particular construction illustrated, the armature 52 of the usual magnet or solenoid 53 is fastened to a stem 54 which bears against the double-ended and differential piston valve 55. The pipe 48 is in communication with a chamber 56, which normally, that is, when the ma et 53 is energized, and its stem 54 raise is in communication with the atmosphere through the valve port 57 and passage 58. Pressure from the main reservoir or other source is supplied through an adjustable restricted orifice 59 to a small reservoir 60, and from there through pipe 61 to a chamber 62 above the piston valve 55. \Vhen the magnet 53 is deenergized, pressure against the upper end of the piston valve 55, aided by a spring 63 on the stem 54, forces said piston valve down, closing the port 57 and opening communication from the chamber 62 to the chamber 56 through the valve port 64 and the passage 65, thereby suppl ing air to the operating cylinder 44 througli pipe 48. It will be noted that the area of the upper end of the piston valve 55 which is exposed to pressure in the chamber 62, is greater after this piston valve has moved down to its open position than when said valve is closed, and the parts are so proportioned that this increased pressure prevents reclosing of the piston valve 55 by energization of the magnet 53 until the pressure in reservoir 60 and chamber 62, has dropped to a predetermined value. The restricted

orifices

50 and 59 are adjusted so that the air escapes from the cylinder 44 through orifice 50 faster than it is supplied from the main reservoir through the restricted orifice 59, so that after a lapse of a certain time, depending upon the size and proportioning of the parts, the pressure in the reservoir 60 and chamber 62 drops to the critical value at which the valve 55 may be closed by the magnet 53. This construction provides a simple apparatus which acts, upon deenergization of the magnet 53, to supply pressure to the cylinder 44 and thereby exert a force tending to shift the engineers brake valve E, and which will also automatically maintain this pressure for a predetermined time. Obviously, the timing operation may be obtained in other ways; and I desire to have it understood that the construction shown is merely illustrative of the desired operation and functions of this part of my system.

The energizing circuit for the magnet 53 of the electropneumatic valve E. P. V. may be traced as follows: From ground, battery 66, conductor 67, magnet 53, conductor 68, contacts 37-36, conductors 69 and 70, and front contact 71 of a relay .6) back to ground. The ener izing circuit for the relay Q, is controlled by the control relay R and relay X, this circuit being readily tnaced on the drawing; This relay Q is preferably quickacting cause the control relays R and X, in this type of inductive impulse transmitting devicef'open their contacts only momentarily. The front contact 71 of relay Q is shunted, when the hold-ofl' lever 18 is in its operated position, by conductors 72, contacts 28, block 22, and conductor 3 to ground; Thus, the magnet 53 will always be eenergized when the contacts 36--37 are opened, and will be deenergized when the relay Q drops, providing the hold-off lever 18 is not in its operated position at the time so as to close contacts 23.

The parts of my system so far described serve to check up the vigilance of the en- 'neer at each caution signal or correspondmg control point, and their operation may now be described with this feature of my system in view. The inductive impulse transmittin means acts to drop the relay Q at each trac Way element T in its stopping controlling condition, that is, with its coil 5 open-circuited, but does not affect said relay when the trackway element has its coil 5 in a closed circuit of low resistance, corresponding to a clear signal. The cautionary impulse, generally speaking, is produced by electro-magnetic induction as the car-carried element passes over the trackway element. Normally, while the train is traveling between trackway elements, the current in the coils 8 produces a certain magneto-motive force which sends a predetermined flux through the yoke 7 and the coil 9. Then the coil 5 of the trackway element is open-circuited, corresponding to a caution signal, said trackway element presents in effect a dead ma netic loop for the yoke 7 of the carcarried e ement L on a passing train, and thus changes the reluctance of the magnetic circuit including said yoke and coils, thereby causin a corresponding change in the flux throng the coil 9. This change in flux induces the current in said coil 9 which varies the current supplied to the control relay R, thereby causing it to open its contacts and momentarily internupt the energizing circuit of the relay Q. The electro-pneumatic valve E. P. V. is of course constructed so that it will operate and unseat the valve 55 (Fig. 2) or valve 104 (Fig. 5) during the momentary opening of the contacts of the relay Q. In the particular arrangement described, the check relay X does not open its contacts at a caution signal, but is used to check the circuit through the field coil 8, although this particular arrangement is not compulsory.

Under clear trafiic conditions. the coil 5 of the trackway element T is in a closed circuit of low resistance and opposes or chokes back the passage of flux through the trackway element, thereby preventing a change of flux in the yoke 7 of a passing car suificient to cause operation of the control relay R. Thus, the quick-acting relay Q is deenergized at each caution signal or corresponding control point, but is not operated under clear traflic conditions.

The engineer upon approaching the cantion signal is expected to operate the holdotl' lever 18 to its operated position. This closes ontacts 22-23 and shunts the front contact 71 of the relay Q, so that the dropping of the relay Q does not affect the magnet 53.

In this way, if the engineer is alert and observes that the si a1 indicates caution, he is able, by a sim i operation of the holdofi' lever, to avoid a. rake application. The op eration of the holdoff device being an active movement, is such as to impress upon the engineer the fact that he has passed a caution signal and entered a danger zone, thereby im posing upon him the responsibility of con trolling his train safely.

If the engineer is careless or indifferent about Watching the signals and fails to note that he is about to pass a caution signal, the operation of the relay Q, the holdo-ii' lever being in the normal position, causes deenergization of the magnet 53 of the electromagnetic valve E. P. V.; and this results in supplying pressure to the cylinder 44, as previously explained. This pressure acts to operate the engineers brake valve E and automatically applies the brakes, unless the engineer by holding the handle 40 prevents such operation. I prefer tomake the pressure exerted upon the engineers brake valve such that, while the engineer may prevent movement, or replace his brake valve after movement, he is obliged to exert himself to do so. This pressur in the cylinder 44 will continue, as previously explained. for a certain selected time, depending upon the size and proportio-ning of the parts. and the adjustment of the restricted

orifices

50 and 59.

It may happen that the train is traveling at such a speed when it passes the caution signal that an immediate service application of the brakes is desirable; and in this case the engineer may not care to hold his brake handle against movement. It will be noted, however, that the engineers brake valve, it operated automatically, will be moved to the service position and forcibly held there for a short time; and since this would bleed the train pipe and require a longer time to recharge and release the brakes, it would be something which the engineer would naturally Wish to avoid. Therefore, even though the engineer does not oppose the automatic brake application, he will find it necessary to move his brake valve handle in opposition to the force exerted against it by the air pressure in the cylinder 44, unless of course he waits until the time interval for which the restricted

orifices

50 and 59 are adjusted has expired, so that in any event he will be penalized for his failure to operate his holdofl device at the right time. Moreover, this penalty is self-executed, so to speak, and obviates the objections to the practice of using recorders and trying to discipline the engineer if records are made agalnst him.

Furthermore, if it should happen that the engineer is incapacitated, or unable for any reason to operate either his holdoft lever or his brake handle, the brakes will be applied F so as to give a service application of the brakes, partly on account of the injurious efl'ect of an emergency application upon the passengers and the equipment, and also because this automatic application of the brakes, when it occurs, Wlll take place at or near the caution signal, service braking dis tance fromthe end of the block. If desired, however, by an obvious modification or adjustment of parts, the apparatus may be arran ed to give an emergency application of the rakes so as to constitute a more severe penalty for a failure to observe the signals and operate the holdofi' device.

Obviously, if the engineer were able to keep his hold-ofl' lever in the operated position, he would not be obliged to note each signal and make a positive movement. To obviate this, the contacts 3637 are provided, together with their associated o crating mechanism. Normally the valve V is in the osition shown in Fig. 3, exhausting the cyllnder 31 and reservoir 29 to atmosphere. When the hold-off lever 18 is operated, the valve V supplies air through the restricted orifice 28 to the reservoir 29, so that the pressure gradually builds up in this reservoir. After a short interval of time, the pressure accumulates behind the piston 32 suificiently to compress the spring 33 and cause the insulated head 35 to separate the contacts 36-37, thereby deenergizin the magnet 53. Consequently, if the ho d-ofl" lever 18 is kept in its operated position longer than a certain time, the magnet 53 will be deenergized and the neumatic device F operated. In other wor s, if the engineer attempts to keep his hold-off lever 18 permanently in the operated osition, he will get into as much trouble as if he failed to make timely operation of the hold-off lever at each caution signal.

The time interval of the operation of the checking device associated with the hold-oil lever 18 may be varied to suit the particular working conditions, so as to give the engineer reasonable latitude in operating the hold-oil. lever while approaching and passing a signal, and yet prevent him keeping the hold-ofi' lever in its operated position while passin from one signal to another.

In t is discussion, the automatic control has been referred to as occurring at a caution signal, or a control point corresponding to a caution signal (see block C); but it should be understood that by a simple and obvious modification of trackway circuits the same automatic control may also be obtained at a stop signal as well as at a caution signal, or, where an overlap is employed, the automatic control can be obtained at the stop signals and not at the caution signals.

In addition to the automatic control above ments T and T" at t e appropriate intermediate point in the block, and providing a time controlled apparatus K on the train for applying the brakes automatically, and in spite of the engineer, unless the train takes more than a predetermined time in traveling from one trackway element of this pair to the other. I

The time controlled apparatus K, while it may take various forms, is illustrated in Fig. 2 as a combined pneumatic and electrical device. A solenoid P is connected in circuit with the contacts of the control relays R and X so as to be energized or deenergized as these contacts are closed or opened, respectively. The core 74 of this solenoid carries an insulated contact piece 75 arranged to cooperate with elongated contact strips 76 for part of the movement of said core. When the solenoid P is energized, its core 74 bears against a differential piston valve 77 and holds it in the closed position. Air pressure from the main reservoir or other source is supplied through a restricted orifice 78 to a small reservoir 79 which communicates through a pipe 80 with the seat of the valve 77. When the solenoid P is deenergized, the pressure in the reservoir 79 unseats the piston valve 77 and raises it to uncover a passage 81 leading through the restricted orifice 82 to atmosphere. The area of the piston valve 77 exposed to pressure when it is unseated is greater than when it is seated, so that the solenoid P, even though reenergized, is incapable of 'reclosing said piston valve until the pressure in the reservoir 79 has dropped to a predetermined amount. In order to temporarily retard the upward movement of the piston valve 77, the chamber 83 above it is closed, with a small port 84 leading to atmosphere, said port being covered by said valve just before it reaches its uppermost extreme. whereby the final upward movement of the valve 77 and core 74 is temporarily retarded until the confined air leaks out around said core. The restricted orifice 82 is adjusted so that the air escapes from the reservoir 79 faster than it is supplied through the restricted orifice 78, and the parts are so proportioned that the sole noid P, which is only momentarily deenergized. will restore its core to the normal position after the lapse of a predetermined interval of time, say, a second or two.

The apparatus K preferably controls an emergency application of the brakes. This emergency application is preferably given by some suitable brake controlling valve which acts to vent the train pipe at the emergency rate. Various devices suitable for this purpose are well known in the art, and I have illustrated such an emergency brake controlling valve G diagrammatically as comprising a magnet or solenoid 85 arranged so as to open a valve 86 and vent the train pipe 87 when deenergized. The normally closed energizing circuit for the magnet 85 includes two branches in multiple, one including the front contact 88 of the relay Q. and the other the contact strips 76 and the contact disc 75.

The operation of the apparatus K is as follows: The parts are normally in the position shown when the train passes a trackway element as T, in the stopping condition, the control relay R is operated the same way as previously described, and the quick acting relay Q, and the solenoid P are simultaneously and momentarily deenerg'zed. While the front contact 88 of the relay Q is open, the circuit for the brake controlling magnet 85 is maintained closed by contact strip 76 and contact disc 75. At the instant the solenoid P is deenergized, the piston valve 77 is raised to uncover passage 81 and commence the gradual reduction in pres sure in the reservoir 79. On account of the temporary retardation of the piston valve 7 7 after it has moved up far enough to close port 84 the contact disc 75 maintains contact with the strips 76 temporarily, at least until the relay Q is again picked up. After this temporary retardation in the movement of the piston valve, however, the c'0re74 reaches its uppermost position by the pressure against said valve, thereby breaking the branch of the circuit for the brake controlling valve 85 which includes the contact strips 76 and the contact disc and although solenoid P is reenergized at the same time as the relay Q, the core 74 remains in its upper posit-ion until, the time interval for which the device is set having ex ired, the pressure below the piston valve 7 is reduced to a point where the attraction of thesolenoid P is sufficient to restore the core to the normal position, whereupon the branch circuit for the brake controlling magnet is closed through the strips 76 and the disc 75. If, now a train should pass over a second trackway element,

as T", before the core 74 is restored to its normal position, an emergency application of the brakes would be automatically given, since one branch of the circuit for magnet 85 is broken at the contact disc. 75, and the other branch would be broken by the deanergization of the relay Q, as a result of the passage of the car-carried element L over this second trackway element. In other words, if the train consumes less than a certain time in passing from one trackway element to the next, the brakes are applied,

this interval of time being that for which the apparatus K is adjusted. If the train consumes more than this time, the brakes are not applied. Thus, by putting the trackway elements in pairs relatively close together, as for exam lo the trackway elements T and T in tlie block B, Fig. 1, a'limiting speed may be enforced at this point, depending upon the timing of the apparatus K, and the distance between this pair of trackway elements. Obviously, by locating this pair of trackway elements closer together, or farther apart, while maintaining the same timing of the apparatus K on the train, various speed limits may be enforced. It will be evident that the apparatus K applies the brakes or not depending upon the average speed of the train in traveling between the trackway elements T and T", rather than its instantaneous speed at the trackway element T"; but by locatihg the trackway elements such a short distance apart that a train would not be able to materially accelerate or decclerate in this short distance, the desired limiting speeds can be determined with sufficient accuracy for practical purposes. The apparatus K does not act at the cautionary trackway element T, since there is time for this apparatus to be reset before the train reaches the next trackwav element T. The features of my system above described may be applied in practice to various working conditions in difi'erent ways. According to one typical application, the first or cautionary trackway element T of a block is located at a distance from the end of that block corresponding with the distance required to make an ordinary service stop, or bring the train to a low and comparatlvely safe speed, such as five or ten miles per hour.

In other words. sufficient distance is provided between the cautionary trackway element T and the end of the block to permit the engineer to make his usual sto in obedience to a caution signal. While t e practice of engineers in stopping their trains varies, the distance ordinarily taken for a. service stop is greater than that actually required to stop the train by a full and cont nued service application. One way of mak ng a service stop is represented diagrammatically in Fi 1 by the curves drawn in dash lines.

In the illustration, it is assumed that the train in question is traveling at its maximum speed of sixty miles per hour (ind cated by dot and dash line 89) when it passes the caution signal, and that a. full service application of the brakes is made at once, the speed being reduced. as indicated by dash line 90, to some intermediate moderate speed, such as thirty or thirty-five miles per hour (indicated at 91, whereupon the brakesare partially oi wholly released, and the train allowed to coast until within approximately the roper distance from the end of the bloc when the final reduction in speed is made by a full service ap lication, as in; dicated by curve 92. Whether the service stop is made according to this method, or in some other way, as for example, by a artial service application held on for the fu 1 stop, there is an intermediate point in the block (indicated by the vertical line 93 in the particular example illustrated in Fig. l) where a moderate speed, shown as 30 miles per hour, is high enough to avoid unnecessa delay in making the service stop, an low enough to permit the train to be sto ped by an ordinar service application be ore reachin the en of the block. Having determine this moderate critical speed limit, and the intermediate point where it should be imposed, the trackwa-y elements T and T will be located at this point and the proper distance a art to act in conjunction with the timingo the apparatus K and give an emergency application of the brakes if this critical speed is exceeded at this point. It is recognized that some engineers have the objectional practice of running by caution signals, that is, delaying a reduction in s eed and running so far into the block at igh speed, in expectation of finding the next 81%181 at caution or clear, as to make it di cult or even impossible to stop. By checkin up the speed of the train at an intermediate point in the block my system stops to a large extent at least, this objectionable practice,because the engineers wish to avoid emergency applications and would, therefore, make a proper and prompt reduction in speed so as to be below the critical speed at this intermediate point. The disciplinary efl'ect of the emergency application may be increased, if desired, by arranging and constructin the emergency brake controlling valve G, in a simple and obvious manner, so that, after having been operated, it must be reset from the ground, or some other inaccessible place, thereby requiring the train to be brought to a stop before this valve can be closed and the train pipe recharged to permit release of the brakes. Or, the re-setting device for the valve G may be time-controlled, so that the brakes cannot be released until after a short time, somewhat longer than that required to bring the train to a stop.

In order to ailord as muchautomatic protection as possible, I prefer to locate the trackway elements T and T" so that, as far as practicable, they would act to stop the tram safely under the worst conditions. For example, the braking curve for an emergene ap lication, starting at maximum 8 e an running out at the end of the b ock, is shown by the full line 94 in Fig. 1. It will be noted that this emergency braking curve, according to the particular example illustrated, starts at the point where the trackway element -T' is located. By doing this, a safe stopping of the train 18 assumed under the worst conditions, because even if the engineer makes no reduction in speed and passes the pair of trackway elements T and T at e maximum running speed, the resulting automatic emergency application will stop the train before it reaches the end of the block. It is evident,

of course, that the braking power of trains point and make an ordinary service sto and although this distance, which may satisfactori as emergency braking distance for maximum speed, it will serve to cut down the speed at least, and in most instances, prevent the train running at high speed from colliding with another train standing) just ahead of the entrance to the next lock. Obviously, the exact location of this pair of trackway elements T and T" in a block, and the variation in their spacin so as to enforce difierent speed limits, wil depend upon the grades, braking wer of the train, and other working con itions for that particular block; and desire to have it understood that the particular location and arrangement indicated in Fig. 1 is merely illustrative of features of my system and is susceptible of variation in practice. Also, while I have shown only one pair of trackway elements T? and '1 in the block, two or more pairs may be employed in the same way to enforce several intermediate speed limitations Since the electropneumatic valve E. P. V. would be operated at the trackway element T the same as at the trackway element T at the caution signal, provided the engineer did not operate his hold-ofi device H, it is desirable to place a marker M along the track to indicate to the engineer the position of this trackway element T", so that he is 'ven op rtunity to operate his hold-ofi evice. similar marker N is also employed where a trackway element, as in the case of the block C, is not located at the signal,

.but at some point further in the block. The

trackway elements T would not ordinaril r uire markers, since they would be sue a s ort distance from the trackway elements T that the engineer might both with a single operation of his hol -ofi device.

Fig. 4 shows a modified construction of the engineers hold-ofi device, which in geny obtained, may not be as great ISO .eral is similar to that shown in Fig. 2. In this modified construction, the contacts 36 37 are opened after a short time following the movement of the hold-off lever 18 to its operated position, by a pneumatic timing device 0, which is normally held inactive by the lever 18 and is released by the movement of said lever to its'operated position. This time device 0 comprises a cylinder 95 containing a piston 96 which is urged in one direction (to the right as viewed in Fig.

I 4) by a spring 97. This movement of the piston 96 by the spring 97 is retarded by the air which is compressed in the righthand end of the cylinder 95, and which can escape only gradually through a restricted orifice 98. The piston rod 99 connected to said piston 96, carries at one end an insulated striking piece 100, which is arranged to strike the contact spring 36 and separate it from its cooperating contact 37, when the piston attains its righthand position. The other end of the piston rod 99 extends through a suitable air-tight packing or stuffing box in the end of the cylinder 95 into position to be engaged by the up er end of the lever 18. A suitable ball 0 eck valve 101 is provided to allow quick return of the piste: 96 to its n-ormal'position shown in The 0 ration of this modified construction of t e engineers hold-ofl' device will be readil apparent. When the lever 18 is move to its operated or hold-off position, the piston 96 is free to be moved gradually to the right by the spring 97 at. a rate determined by the adjustment of the restricted orifice 98; and after the lapse of a PIG: determined time, the striking piece 100 opens the contacts 3637. Thus, the lever 18 may be swung to its operated position, held there a short time and then returned to the normal position, without opening contacts 3637 but if said lever is held in its operated posit-ion longer than a certain time for which the device is adjusted, the contacts 3637 will be opened to cause deenergization of the electropneumatic valve E. P. V. in the same way as previously described. I

Fig. 5 shows a modified construction of my system, in which the a plication of ressure to the engineers bra e valve, resu ting from a failure of the engineer to operate his \hold-ofi' device H at a caution signal, will continue until the fireman, or some person other than the engineer, releases this pressure. In this modification, the engineers hold-off device is the same as shown in Fig. 2, and likewise the pneumatic device F for operating the engineers brake valve except that the cylinder 44 in the modified construction is not provided with the restricted orifice 50 as in Fig. 2. Also, the electropneumatic valve E. P. V. is modified so that it is reset electrically, rather than automaticall by a reduction in pressure. In this modlfied construction of the electropneumatic valve E. P. V., the stem 54 is provided with an insulated contact disc 102 which bridges fixed contacts 103-103 when said stem is in its uppermost position, as shown in Fig. 5. ThlS stem 54 carries two op osed valves 104 and 105. The upper va vs 104 controlsthe sup 1y of com ressed air from an upper cham r 106, w ich is connected by pipe 107 to the main reservoir, to the lower chamber 108, which communicates by ipe 48 with the cylinder 44. The lower va ve 105 controls the connection be tween the chamber 108 and a passage 109 leading to atmosphere. A sprin 110 on the stem 54 sets in conjunction wit reservoir pressure on the control valve 104 to move the stem downward when the magnet 53 is deenergized. In, this arrangement, the magnet 53 when energized is strong enough to reclose the valve 104 against main reservoir pressure as well as hold it closed.

The firemans reset device U comprises a manually operable plunger 111 rojecting out of a casing 112 in which t e several parts of the device are enclosed in the same way as the engineers holdout device H. This plunger is guided by said casing and a lug 113 integral with said casing. The plunger 111 has an insulated head 114 at its lower end arranged to move a contact spring 115 into contact with its cooperating contact 116 when said plunger is pushed down. A compression spring 117 between the lug 113 and a collar 118 on the plunger 111 holds the plunger yieldingly in its normal uppermost position, as shown in Fi 5. The plunger 111, like the lever 18 o the engineers h0ld 0if device H, is provided with a safety appliance for preventing it being carelessly or maliciously held or fastened down. This safety appliance comprises a lever 119 suitably pivoted between its ends to the casing 112. The lever 119 is biased to swing in one direction (counterclockwise as viewed in Fig. 5) by a spring 120, and is swung in the opposite direction by the upward movement of the plunger 111, the end of said lever being engaged by the collar 118. This lever 119 carries an insulated striking piece 121 arranged to hit a contact spring 122 and separate it from lts cooperating contact 123, when said lever is swung by the spring 120 to its extreme position. The movement of the lever 119 under the influence of the spring 120 s retarded by a dashpot comprising a cylinder 124, having a restricted exhaust port 125 in its bottom, and a piston 126, provided with flexible packing and connected by a. rod 127 to the lever 119.

Normally, the parts of the firemans reset device U are in the position shown in Fig. 5.

the main When the plunger 111 is pressed down by the fireman to close contacts 115-116, the lever 119 is free to be swung by the spring 120. The downward movement of the iston 126 is retarded by the slow escape 0 air from the cylinder 124 through the exhaust port 125, so that the lever 119 does not move far enough to open contacts 122-123 until after the lapse of a short interval of time. \Vhen the plunger 111 is released, the spring 11? returns it and the lever 119 to the normal position, the flexible packing of the piston 126 being such as to permit its unretarded upward movement.

In the modification of Fig. 5, the circuit for normally maintaining the magnet 53 of the electromagnet valve E. P. V. energized may be traced as follows: commencing at ground, conductor 128, contacts 103 and contact disc 102,

conductors

129 and 130, battery 131, conductor 132, magnet 53, conductor 133, contacts 36-37, conductor 134, contacts 122-123,

conductors

135 and 136, front contact 71 of the relay Q, and conductor 137 back to ground. It will be noted that this circuit includes in series the contacts 36-37 and the contacts 122-123, so that if either the engineefishold-off lever 18 or the liremans reset plunger 111 is held in its operated position too long, the magnet is chenergized. When the engineerss hold-off lever 18 is moved to the operated position, partly shown in dotted lines, the closing of contacts 23 establish a shunt for the front contact 71 of the relay Q, comprising

conductors

138, 139 and said contacts 23, thereby maintainin the magnet 53 energized independently o the dropping of the relay Q. The contacts 103-102 controlled by the stem 54 of the magnet 53 are shunted when the plunger 111 is moved down to close contacts 115-116, this

shunt comprising conductors

140, 141 and said contacts 115-116.

The operation of the modified construction of my system shown in Fig. 5 is very similar to that already described, and only the different features need be articularly pointed out. If the en ineer fails to operate his hold-01f device at a caution signal, the droppin of relay Q, deenergizes magnet 53, thus c osing valve 105 and opening valve 104 to supply pressure to the cylinder 44. When the magnet 53 is deenergized, the contacts 102-103 open, so that said magnet will not be reenergized when the front contact 71 of the relay Q, recloses. Also, the engineer in not able to reenergize the magnet 53 by operating his hold-ofi' lever 18 to close contacts 23. The magnet 53 can only be recnergized by operation of the plunger 111 to close the contacts 115-116.

The plunger 111 is in practice located at such a lace that it cannot be reached by he retains hold of his and the engineer therethe engineer while brake valve handle,

trolling ine relay 6. On the car,

fore must call u on the fireman, or'some one else, to operate this reset plunger 111. When the contacts 115-116 are closed, the magnet 53 is reenergized, the valve 104 closed to cut off further supply of pressure from the main reservoir, and the valve 105 is opened to exhaust the ressure already in the cylinder 44. It Wll l be observed that this modified arrangement provides an additional element of publicity to the failure of the engineer to operate his holdout device since his neglect is brought to the attention of the fireman. It is contemplated that this,-together with the annoyance to the fireman, will induce the engineer to be careful in observing the signals.

Fi 6 illustrates a modified construction whic may be employed for the firemans reset device. In this modification, instead of the plunger 111 for actuating the lever 119 and the contact spring 115, as in Fig. 5, a threaded shaft 142, with a crank 143 for turning it, carries a nut 144, which is arranged to engage the lever 119 and the contact spring 115 in its opposite extreme positions. As the shaft 142 is rotated the nut travels along said shaft, being held against rotation in a suitable manner, as by a. rod 145. When the fireman desires to close the contacts 115-116, he turns the crank 145 in one direction to cause the nut 144 to travel along the shaft until it engages contact spring 115, the lever 119 being released at the same time. By turning the crank 143 in the opposite direction, the nut 144 may be moved back to its normal position so as to restore lever 119 and prevent opening of contacts 122-123. This arrangement makes it more diflicult for the fireman to close the contacts 115-116, and then restore the parts to the normal position, thereby adding to his trouble and annoyance. Obviously, the exhaust port 125 must be small enough to give the fireman enough time to move the nut 144 down and back.

In Fig. 7, I have illustrated the traekway apparatus used when the indication of the fixed signals is relied upon to inform the engineer of the entrance of his train into a caution block, and no provision-is made for automatic control at the caution signal or corresponding control point. It will be observed that this modification of the trackway equipment consists merely in omitting the trackway element T, at the signal or correspondin control point, together with its cononly the relay Q and the time-controlled apparatus K are employed, the E. P. V., the device F for operating the engineers brake valve, the hold-off device H, and their associated parts and circuits, being omit-ted. In this arrangement, if the engineer fails to observe the caution indication of a signal, or fails to reduce the speed of his train in obedience the location of the trackway elements T--T",

but this is optional.

Fig. 8 illustrates how two or more pairs of speed limiting trackway elements T'1 may be employed in the same block, so as to enforce two or more different speed restrictions upon the train during its progress through such block. These pairs of trackway elements T-T" may be located at any desired points in the block, and spaced apart an appropriate distance, so as to cooperate with the time-controlled device K on the car and enforce any desired speed limits, the location and the braking curves shown in Fig. 8 being merely illustrative. This arrangement may be used with or without autolnatic control at the signal, or corresponding control point. The location of the several pairs of trackway elements TT is preferably indicated by markers as M.

Fig. 9 illustrates how a. pair of trackwa elements T-T" may be used to compel a reduction in speed upon the approach to a switch, or crossover 147. In this arrangement 2. pair of trackway elements, or a plurality of pairs, if desired, spaced the suitable distance apart, are located at the appropriate point or points in the rear of the switch or crossover, so as to enforce the desired speed restrictions in accordance with the principles hereinbcfore explained; and the controlling circuit for the relay or relays governing the coils of these trackway elements is taken through a switch box, as 150, or a circuit controller on the signal governing trafiic over this switch or crossover, through a like control device. in accordance with well known signaling practice, so that the coils of these trackway elements are open circuited when the switch or crossover is set up for a low speed route.

Fig. 10 illustrates how a pair or pairs of trackway elements 151 may be employed to compel a reduction in speed on the approach to a sharp curve 152. In this case the speed limit being always enforced, the trackway elements 151 are merely the magnetic members without coils. The way in which the same principle of control may be applied to any permanent hazard, such as drawbridges, yard limits and the like, will be evident, and need not be shown or described in detail.

I have shown and described different embodiments of my invention, and explained the rinciples thereof and the manner in whici I prefer to practice the invention; but it is evident that various adaptations and modifications, other than those illustrated and described, may be made in my improved system by one skilled in the art without departing from the scope of the invention or deviating from its essential functions and operation. For example, my system is applicable to electric roads as well as steam roads, and may be used in connection with any of the existing block signal systems, with either direct current or alternating current track circuit, all withoutany changes other than the substitution and selection of well known relays and other devices so as to correspond with the form of energy and the type of signal system.

It should be understood that while I have illustrated my invention applied to a system of three-position signaling, the same principles and practice may be employed in connection with two-position home and distant signals. Where three-position signaling is used, and some of the blocks are longer than that required to make a service stop, as is often the case, the trackway element T in these blocks, assuming it is desired to have it convey a true caution indication, would be located some distance in advance of the signal and provided with a marker, as shown in block C, Fig. 1; whereas, with two-position home and distant signals, the trackway element T could be located at the distant signal. These and other adaptations of my system to the differences in the practice of block signaling on railroads, including the application of my system to manually controlled block systems, will be readily apparent, and need not be specifically shown and described.

Although I have particularly described the construction of one physical embodiment of my invention. and explained the operation and principle thereof, neverthe less, I desire to have it understood that the form selected is merely illustrative. but does not exhaust the possible physical embodiments of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A train control system for railroads divided into blocks, including trackway devices and circuits and vehicle-carried equipment. and comprising means for giving a service brake application, subject to prevention by the engineer, near the entrance to each block when the block ahead is occupied, whereby the engineer may run the vehicle unbrakcd into a caution block if he so elects. and means comprising two trackwa y devices spaced relatively close together, and car-carried means controlled thereby for giving a stronger brake application independently of the engineer at one or more intermediate points in the block dependent upon the speed of the vehicle at that point or points. i

2. In an automatic train control system for railroads divided into blocks, car equipment comprising cautionary control devices adapted to give an automatic brake application subject to prevention by the engineer, and an emergency control appliance adapted to give a stronger brake application independently of the engineer when subjected to successive controlling influences at less than a predetermined time interval apart, an impulse receiving device on the car, track elements adapted to cooperate therewith, there being one track element near the entrance to each block and a pair at one or more intermediate points in the block, and trackway circuits for controlling said track elements of each block in accordance with traffic conditions in the next block in ad Vance.

3. In an automatic train control system for railroads divided into blocks, a cautionary track element near the entrance to each block, emergency track elements spaced relatively close together in pairs at an intermediate point or points in the block, trackway circuits for regulating the controlling condition of said track elements of each block in accordance with traflic conditions in the block ahead, and automatic train control equipment on a vehicle adapted to be governed by said track elements, said equipment comprising means controlled by the cautionary track elements for giving a service brake application subject to prevention by the engineer, and other means controlled by the emergency track elements for giving a stronger brake application independently of the engineer.

4. In an automatic train control system 1' or railroads divided into blocks, train control apparatus on a vehicle adapted to control its movement in two stages, the first stage being independent of the speed of the vehicle and being preventable by the engineer without applying the brakes, the second stage being dependent upon excessive speed and non-preventable by the engineer, and traffic controlled means for governing the operation of said apparatus to produce the different stages of control in succession, the first near the entrance to a block, and the other at an intermediate point or points therein.

5. In an automatic train control system for railroads divided into blocks, the combination with a vehicle equipped with an air-brake system, train control means on said vehicle comprising a brake-setting valve acting on the air-brake system to produce an automatic application of the brakes, a manually operable hold-ofi' device effective for a limited time only when operated and without effecting any operation of the air-brake system during said limited time, control means for causing operation of the brakesetting valve unless the hold-off device is in its effective condition, said control means being adapted to be actuated by track devices in each block which are overned in accordance with tratlic conditions in the block ahead, and other automatic means operated when successive actuations of said control means occur in less than a predetermined interval of time for producing a brake application which is not preventable by the engineer.

6. In an automatic train control system for railroads, automatic train control apparatus on a vehicle including a cautionary control device adapted to give a service brake application, an emergency control appliance adapted to give an emergency brake application, a manually operable holdoff device effective for a limited tinie without tending to apply the brakes to prevent operation of the cautionary control device but not the emergency control appliance, and means partly on the vehicle and partly along the track for causing operation of said cautionary control device at a control point independent of the speed of the vehicle, and said emergency control appliance at a successive point.

7. Automatic train control apparatus for railway vehicles comprising, normally inactive brake control apparatus controlled from the trackway and adapted when ope'rated to tend to produce an automatic application of the brakes Which the engineer cannot easily prevent, and a manually operable hold-ofi' device, easily operable by the engineer but effective only if operated prior to the initiation of the operation of said apparatus for preventing such operation in spite of its control from the trackway for a limited time only.

8. In an automatic train control system. the combination with a car equipped with an air-brake system, ear-carried train control apparatus comprising control means adapted to be automatically actuated from the trackway at control points along the track in accordance with trailic conditions ahead, a brake setting appliance governed by said control means and acting to vent the brake pipe of the air-brake system and cause an automatic brake application, a manually operable hold-oil device for preventing operation of the brake setting appliance by said control means, said hold-off device being effective only if actuated prior to the operation of said appliance and if held in its hold-ofi position longer than a predetermined interval of time acting automatically to initiate operation of said brake setting appliance.

9. In an automatic train control system, the combination with car-carried brake control apparatus cooperating with the airbrakes of the car to produce an automatic brake application, of means for automatically initiating the operation of said ap ratus from the trackway under unfavora le traliic conditions; a. hold-oil device conveniently accessible for operation by the engineer and effective only if operated prior to the initiation of operation of said apparatus, for preventing such operation in spite of its control from the trackway', said holdofi' device if kept in the hold-off condition longer than a predetermined limited time after each operation thereof acting automatically to actuate said apparatus and cause a brake application, whereby the engineer may prevent an automatic brake application only if he anticipates the operation of the brake control apparatus by a. manual operation of the hold-off device and restores the hold-01f device to normal within a limited time.

10. In an automatic train control system for railroads, thecombination with a car equipped with a braking system and car carried train control apparatus governing said braking system, of a manually operable hold-ofl device effective only if put in its hold-oil condition prior to initiation of operation of said apparatus to prevent operation of said apparatus, and time-controlled means initiated and restored automatically by the hold-off device as it is chan ed to its hold-oii' condition and normalcon ition respectively, said time controlled means after lapse of a limited interval of time acting to cause an independent operation of said apparatus.

11. In an automatic train control system for railroads, car-carried train control apparatus and a normally closed governing circuit therefor, a control relay having contacts included in said circuit, means on the car and on the track cooperating to cause de-energization of said relay under unfavorable traffic conditions at predetermined control points, a shunt for said contacts, a manually operable circuit controller for closing said shunt, and a time element device released and restored by the operation of said circuit controller for opening said circuit after the lapse of a short interval of time, whereby the manually operable circuit controller cannot be kept closed without causing operation of the train control apparatus.

12. In an automatic train control system for railroads, the combination with a brakesetting device provided with a handle for preventing its movement, power operated means for e e t ng a.- strong pressure te dmaticall to initiate operation of said power operate means.

13. In an automatic train control system for railroads, the combination with an engineers brake valve; of power operated means for exerting a strong presure tending to operate said brake valve to a brake applying position and for continuing such pressure until restored; manually operable sis means out of the control of the engineer while at his post for restoring said power operated means; and automatic means partly on the vehicle and partly along the track, having its efi'ective action subject to prevention b the engineer, for causing operation of said power operated means.

14. In an automatic train control system for regulating the movement of trains over tracks divided into blocks, means partly on the train and partly on the track tending to automatically ap ly the brakes near the entrance to each lock and again near the exit end thereof if the next block in advance is then occupied, acknowled ing means on the train conveniently opera is by the engineer and permitting him to prevent such brake application and proceed with his train unbraked only provided he operates said acknowledgin means within a limited time prior to sue tendency. to apply the brakes and provided he thereafter restores the acknowledging means to normal within a limited time, and means for causing an automatic brake application, dependent upon the speed of the train and which the englneer can not prevent, durin the progress of the train through each bloc with the next block in advance then occupied.

15. In a system for automaticall controlling train movement on railroa s having tracks divided into blocks, the combination with brake control apparatus on a, train, of influence communicating means partly on the train and partly on the track automatically tending to actuate said apparatus at predetermined control points adjacent the en trance and also out ends of each block if the next block in advance is then occupied, a hold-ofi' device on the train manually operable by the engineer and efiective for a limited time only for each operation to prevent such actuation ofsai apparatus, and

oth r means on the train g ern d y id influence communicating means for automatically applying the brakes independently of said hold-ofl' device if the train exceeds the predetermied s eed limit during its progress through ab ock with the next block in advance then occupied.

16. In an automatic train control system for railroads having tracks divided into blocks, a brake setting appliance on the train cooperating With the air-brake system there of to produce an automatic service application of the brakes, influence transmitting means on the track cooperating with receiving means on the train inductively through an intervening air-gap and tending to initiate operation of said appliance at a predetermined control point in each block if the next block in advance is then occupied, acknowledging means on the train, manually operable by the engineer and effective for each operation only while the train is traveling a limited distance less than a block length, for preventing operation of said apliance notwithstanding the action of said influence transmitting means, said acknowledging means being incapable of restoring said appliance to permit release of the brakes after operation thereof, means for restoring said appliance, and other means on the train governed by said influence transmitting means for producing an automatic brake aplication independent of said acknowledglng means if the speed of the train is excessive.

17. In a train control system, a brake control device on a vehicle, traflic controlled means for governing said device, and manually operable means efl'ective, only when said device is in its normal inactive condition for maintainin it inactive for a limited time ,onl independently of its control by said tra 0 controlled means.

18. In a train control system, brake control apparatus on a vehicle, traffic controlled means partly on the vehicle and partly on the track for governing said apparatus in accordance with traific conditions, and manually operable means having a limited time of effective operation for maintaining the apparatus inactive independently of its control by said trailic controlled means, said manually operable means being effective only when the apparatus is in its normal inactive condition- 19. In a train control system, a normally energized brake control device on a vehicle, means for controlling said device from the trackway in accordance with traflic conditions, a circuit controller opened when said device is operated, a normally open auxiliary energlzing circuit for said device including said circuit controller, and manually operable means for closing the auxiliary energizing circuit at another point for a limited time only.

20. In a train control system, a brake control device on a vehicle, an energizing circuit therefor governed from the trackway in accordance with traflic conditions, an auxiliary circuit for energizing said device, circuit controlling means for breaking the auxiliary circuit at one point when said device is operated, manually operable means i'or closin the auxiliary circuit at another point, an means associated with the manually operable means for breaking the main energizing circuit for said device after an interval of time following the operation of said manually operable means.

2t. In a train control system, a brake control device on a vehicle governed from the trackway in accordance, with traflic conditions, said device when set into operation continuing in operation until restored, manually operable means adapted when operated to prevent operation of the brake control device provided said means is shifted prior to the control of the device from the trackway, and other manually operable means having a limited time of effective action for restoring said device to normal.

.22. In a train control system, automatic traincontrol apparatus on a vehicle conditioned from the trackway and adapted to have its operation prevented by the engineer, said apparatus acting unless its operation is t us prevented to cause an automatic brake application, said apparatus also continuing in operation until restored, and means having a limited time of effective action for restoring said apparatus.

23. In a train control system, brake control means on a vehicle governed from the trackway in accordance with traffic conditions and adapted when set into operation to continue in operation until restored, and means having a limited time of eflective operation for maintaining said brake control means inactive independently of its control from the trackway, and other manually operable means inaccessible to the engineer While at his post for restoring said brake control means after operation thereof.

24. In a train control system, a normally energized brake control device on a vehicle governed from the trackway in accordance with traffic conditions, said device when set into operation continuing in operation until restored, a restoring circuit for said device, and manually operable means for closing said circuit, said means when maintained in its operated condition longer than a predetermined interval of time acting automatically to break said circuit.

25. In a train control system, train control means on a vehicle having a normally closed operating circuit and an auxiliary retaining circuit, and manually operable means for closing the retaining circuit, said manually operable means when operated opening the operating circuit after an interval of time.

26. In an automatic train control system, automatic apparatus on a vehicle adapted to be controlled from the trackway for causing a brake application, manually controlled means for preventing such brake application if actuated prior to the control of said apparatus from the trackway, and a device for restoring saidappara-tusto normal, said device automatically causing a brake application if maintained .in its restoring condition.

27 Railway traflic controlling apparatus comprising normally inactive means carried on a vehicle for applying the brakes, track- Way devices for co-operation with said means to cause an application of the brakes, and manually operable means on said vehicle effective for a given interval of time to prevent a brake application due to co-operation of said first mentioned means with a trackway device.

28. Railway t-raflic controlling apparatus comprising brake application means on a vehicle, devices located at intervals in the trackway and arranged to co-operate with said means to cause a brake application in the event of dangerous traflic conditions, and manually operable means on the vehicle effective for a given interval of time to prevent a brake application due to such co-operation.

29. Railway traffic controlling apparatus comprising a circuit on a vehicle including a normally closed contact, devices located at intervals in the trackway for opening said contact, manually operable means on the vehicle for closing a branch around said contact and effective for a given interval of time to prevent the de-energization of said circuit by a trackway device, and means controlled by said circuit for causing a brake application when the circuit is open.

30. Railway trafiic controlling apparatus comprising an elcctro-r'esponsive device on a vehicle, a vehicle carried circuit for said device including a source oi current and a normally closed contact, devices locatd at intervals in the trackway for opening said contact, manually operable means on the vehicle for closing a branch around said contact and effective for a given interval of time to prevent de-energizatio-n of said electro-res onsive device by a trackway device, and means controlled by said electric responsive device when tie-energized for causing a brake application.

31. Railway traflic controlling apparatus comprising normally inactive means carried on a vehicle for app-lying the brakes, trackway devices located at intervals and controlled by trafiic conditions in advance for cooperation with said means to cause an application of the brakes, and manually operable means on said vehicle effective for a given interval of time to prevent a brake application due to co-operation of said first-mentioned means with a trackway device.

32. Railway traffic controlling apparatus comprising devices located at intervals in thetrackway and each controlled as to condition by traffic conditions in advance, apparatus on a vehicle co-acting with said devices and arranged to apply the brakes upon v encountering a device which is in unsafe condition but not a device in safe condition, and manually operable means on the vehicle effective for a glvcn interval of time to prevent a brake application due to co-operation of said apparatus with a trackway device in unsafe condition.

33. Railway traflic controlling apparatus comprisin normally inactive mechanism on a. vehicle or applying the brakes, trackway devices for co-operation with said mecha nism to cause an application of the brakes, a manually operable member on the vehicle, and normally inefl'ective means on the vehicle placed in effective condition for a fixed time interval upon operation of said member, said means when in effective condition opcrating to prevent an application of the brakes due to co-operation of a trackway device with said mechanism.

34. Railway traffic controlling apparatus comprising normally inactive automatic brake application mechanism on a vehicle, means controlled from the trackway for setting said mechanism into operation under unsafe traflic conditions, and manually controllable means on the vehicle effective for a limited interval of time to prevent said mechanism being set into operation from the trackway.

35. Railway traflic controlling apparatus comprising a magnet on a vehicle, apparatus located in the trackway for causing said magnet to be energized while traffic conditions in advance are safe bntnotwhen traffic conditions in advance are dangerous, brake application mechanism onsaid vehicle, means on the vehicle actuated by the deenergization of said magnet for setting said brake application mechanism into operation, and manually operable means on the vehicle effective for a limited time interval for preventing said mechanism from being set into operation.

36. In an automatic train control system for railroads, the combination with a normally inactive brake applying means on a vehicle adapted if operated to cause-an automatic application of the brakes of the vehicle, said brake applying means if once operated continuing in o eration until restored, means for restoring t e brake applying means to normal after operation thereof, a normally energized electro-pneumatic valve acting if- Gil deenergized to operate said brake applying means, governing means fgrsaid valve partly on the vehicle and partly on the track for causing deenergization of the valve under dangerous trailic conditions but not under safe trafiic conditions, a circuit for maintaining said valve energized independently of its control by said governing means, and manually operable means readily accesible to the operator of the vehicle and acting in its active condition to close said circuit, said manually operable means acting automatically to break said circuit after the lapse of a predetermined interval of time when kept in its active condition.

37. In an automatic train control system, the combination with automatic brake applying apparatus on a vehicle adapted it once operated to continue in operation until restored, means for immediately initiating the actuation of said apparatus from the trackway under dangerous traflic conditions only, manually operable means readily accessible to the operator of the vehicle for preventing such actuation of said apparatus notwithstanding its control from the trackway, said manually operable means being effective to prevent actuation of said apparatus for only a limited time after each manual operation and only if such operation occurs prior to the actuation of said apparatus, and a separate manually operable devicefor restoring said apparatus to normal.

38. An automatic train control system for railroads comprising, an automatic brakesetting appliance on a vehicle including a normally energized electro-pneumatic valve, traflic controlled trackway means and carcarried means cooperating therewith for causing immediate deenergization of said electro-pneumatic valve under dangerous traffic conditions unless said valve is otherwise maintained energized, a normally open circuit adapted if closed to maintain said electro-pneumatic valve energized reguardless of its control by said trackway and car-carried means, means operable manually by the operator of the vehicle to close said circuit for only a limited time after each operation, said brake-setting appliance if once operated by the deenergization of the electro-pnenmatic valve continuing in operation until restored irrespective of said manually operable means, and a separate manually operable device for restoring the brake-,

setting appliance to normal.

39. In an automatic train control system for railroads, the combination with an automatic brake-setting appliance on a vehicle including a normally energized electropneumatic valve; trafiic controlled means partly on the vehicle and partly on the track for causing deenergization of said electropneumatic valve under dangerous tratfic con ditions but not under safe traflic conditions; and means operable manually by the opera.- tor of the vehicle and effective only for a limited time after each operation for maintaining said electro-pneumatic valve energized independently of its control from the trackway by said tratiic controlled means; said mannually operable means including biased circuit controlling means actuated by pressure in opposition to its bias, and a. reservoir used for supplying fluid pressure to said circuit controlling means, the pressure in said reservoir varying through an orifice of restricted area in accordance with the lapse of time after said manually operable means has been placed in its active condition.

40. In a train control system for railroads, the combination with a vehicle equipped with an automatic air brake system of the usual type; brake applying mechanism operable by fluid pressure to act upon the air bralre system and cause an automatic application of the brakes; a normally energized electro-pneumatic valve governing the operation of said mechanism; means for governing said electro-pneumatic valve from the trackway in accordance with trailic conditions; an manually operable means on the vehicle readily accessible to the operator of the vehicle for maintaining said electropneumatic valvei energized independently of its control from the trackway for only a limited time after each manual operation; said manually operable means including a cylinder, a piston therein, a spring tending to move the piston in one direction, circuit controlling means actuated by said piston when shifted in the other direction in opposition to said spring by fluid pressure in said cylinder, a reservoir, a source of fluid pressure, and a manually actuated valve for supplying pressure from said source to the reservoir. I

41. In a permissive automatic train control system, the combination with carcarried brake control apparatus includin a normally closed valve acting when opene to cause an automatic brake application, im-

pulse transmitting means partly on the vehicle and partly on the track cooperating through-an intervening air-gap and automatically tending to open said valve under unfavorable traffic conditions at predetermined control points, and an acknowledging device on the car conveniently operable by the engineer for maintaining said valve closed independently of the control of said impulse transmitting means, said acknowledging device including means responsive to the lapse of time, which means is set into operation each time said device is manually operated and which renders said device ineffective if kept in its operated position longer than a predetermined. time, said