US1649163A - Automatic train-control system - Google Patents

Description

Nov. 15, I 92 7.

WJQHOWE AUTOMATIC TRAIN CONTROL SYSTEM Filed Dec.

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INVENTUH 74 $4 k W ilk Patented Mgr I PATENT OFFHCE.

UNlTEFD STATES WINTHROP K. HOVJ'E, GE RGCHESTER, NEW YORK, ASSIGNOR 'IO GENERAL RAILW'AY SIGNAL COMPANY, 013 GATES, NEW YGRK, A CORPORATION OF NEW YORK.

AUTOMATIC TBAIN CONTROL SYSTEM.

Application filed December lhis invention relates to systems for au-- tomatically controlling the speed of railway trains.

It is desirable that a system for automatically controlling railway trains should, for reasons which are quite generally understood and appreciated by those skilled in the art o'r' railway signaling, provide for controlling the speed of a train under conditions where the train should proceed cautiously, in obedience to a caution signal, or around a curve, or down a dangerous grade, or the like. Also, such a system should preferably be constructed so that the control thereof is accomplished in accordance with the principles and practices which have been found to be safe and economical by long trial and experience, and particularly in accordance with the general practices in track circuited block signaling systems.

Briefly, without attempting to define exactly the scope and nature of the invention, it is contemplated according to this invention, to divide the traclrway for the trains into electrically isolated track circuited blocks and to provide a suitable controlling ramp or other means for each block which is adapted to cooperate with a shoe or other device carried by the train, so that by the mechanical and electrical cooperation of said shoe with said ramp the information necessary for the proper operation of the system concerning the traflic conditions in a certain number of blocks ahead can be communicated from the traclnvay to the moving train in a simple and reliable manner. In case the train should enter a block in which it should proceed cautiously in obedience to a caution signal and be prepared to stop at the end of that block, certain mechanism on the train is set into operation to determine the safe permissive speed for the train at the different points in its travel through said block; and this mechanism is arranged to cooperate with a suitable appliance responding to the actual speed of tae train, so that. as said u'icchanism moves and im' poses more and more of a lin'iitation on the permissive speed ol the train. determined with regard to the length oi. the block. the braking equipment of the train, the weight of the train, grades and curves in the track and other such factors as altect the distance in which the train can be brought to a stop 4, 1915. Serial No. 65,9'71.

by its brakes, unless the actual speed of the t am is reduced to correspond with the permissive speed prescribed by said mechanism, a warning signal will be given and then subsequently, it this warning signal is disregarded, the brakes of the train will be automatically applied. It is a well known fact to those skilled in the art of railway signaling that, in order to facilitate and expedite tratiic, the blocks are made of varying lengths; and consequently, while said mechanism which establishes or determines the pern' issive speed for the train will give accurate results for blocks of substantially the same length and physical characteristics, this mechanism cannot be used for other blocks ot a different length without a very appreciable error, with the result of either unnecessarily delaying traffic, or of failing to control the train with proper safety.

lVith these considerations in view, one of the principal objects of this invention is to devise a system for automatically controlling railway trains, in which in controlling the speed of the train, due allowance Will be made for the varying length of the blocks into which the trackway for the train is divided.

A further object of the invention is to devise a system for automatically controlling railway trains in which means is provided whereby the speed of the train may be properly governed irrespective of the length of the several blocks over which the train travels.

Other objects and advantages will appear as the description of the invention progresses, and the novel features of the invention will be particularly pointed out in the appended claims.

The invention primarily consists i the parts, in the arrangements and combinations of parts, and in the controlling circuits therefor, which will be fully set forth herematter.

In describing the invention in detail, retercucc is had to the accon'ipanying drawing, in which is illustrated the preferred physical embodiment of the invention and in which The figure is a diagrammatic illustration of the parts of a system for automatically controlling the speed of railway trains em bodying the invention, the parts being shown arbitrarily in certain chosen positions considered to be best adapted for showing the construction and the electrical connections between the parts rather than .trictly in accordance with their actual construction, arrangement and location, said figure illustrating the parts of the system carried on the train and the arrangement of parts and electrical connections therefor along the trackway.

Referring to the accompanying drawing, one track rail 1 of the trackway over which the train passes is electrically continuous, the separate rail sections thereof being suitably bonded together: and the other track rail 2 is divided by suitable insulating joints 3 into blocks A, B, (l. D and E. These blocks may be of any length necessary to obtain the desired spacing of the trains;

' but, as pointed out hereinbefore, in practice all of the blocks of a particular railway will not be of the same length. For the purpose of rendering more intelligible the features of the construction and operation of the system embodying this invention. whereby due allowance is made for the different lengths of the blocks, the block Bis assumed to rcprc sent a short block, the block D a longer block and the block C a. still longer block.

- It is to be understood that the particular successive occurrence of the different length blocks illustrated is not compulsory, since several blocks of the same length may follow each other, then anynumber of longer blocks or shorter blocks, and so on in any sequence. The normal direction of traffic is indicated by the arrow T.

The parts and electrical connections therefor associated with each block are the same, and for simplicity and clearness said parts and electrical connections therefor associated with the blocks C and D, will be given the salne reference characters as said parts and electrical connections therefor associated with the block B, with the distinctive exponents 1? and 2 added thereto.

At one end of each block, preferably the exit end, is a track battery 4:. which is connected across the track rails 1 and 2; and at the other end of each block is a track relay 5 which is connected by conductors 6 and 7 across the track rails. The track battery 4 and the track relay 5 of each block, together with the track rails 1 and 2 of that block. constitute the well known normally closed track circuit. the operation of which will be clear to those skilled in the art of railway signaling without further description. Each track relay 5 has two armatures 8 and 9 which are represented in the drawing according to established convention. Adjacent to the entrance to each block is a ramp R which is supported in any suitable way adjacent to one of the track rails and in such a manner as to be insulated from the track rails. Each ramp R is provided with suitable controlling circuits by means of which an electrical difference of potential created by suitable sources of electrical energy, as two batteries 10 and 11, may be established at times between said ramp R and the continuous track rail 1.

Located along the trackway, preferably between the track rails 1 and 2, are suitable selector ramps SR, SC and SL which are located at different points between the track rails 1 and 2 in order to determine the particular selection obtainable by the particular ramps. These selector ramps act like cams or similar devices for mechanically actuating cooperating tappets carried by the train, and may be supported in any suitable way upon the ties of the trackway, preferably resiliently. The ends of the selector ramps gradually slope upwardly so that the tappets carried by the train may engage said ramps without undue shock; and said selector ramps may be of any length desired to operate the tappets carried by the train slowly. Further factors affecting the location and arrangement of the selector ramps will be set forth hereinafter.

The electrical connections between the ramps R. the armatures of the track relays 5, and the batteries 10 and 11, will not be described in detail, since these electrical connections and the different operating circuits will be fully set forth in the description of the operation.

The train is shown diagrammatically as comprising two pairs of wheels 1212 and l414 connected by the usual axles 13 and 15; and the body or frame of the vehicle or of the separate cars or locomotives constituting a train is represented by a bar 16 con nected to the axles 13 and 15. A contact, shoe is carried by the train in any suitable way in position to cooperate with the ramps R, and is shown as mounted upon a bracket 17, which for simplicity is assumed to be made of some insulating material and which is secured to the journal box or axle 15. Mounted on the bracket 17 is a vertically movable plunger or shoe 18 which is pressed downwardly by a spring 19. The shoe 18 is arranged in the same plane as the ramps R and is designed to make electrical contact with said ramps as the train passes them. and also to actuate a suitable circuit controlling device. To accomplish this latter function. the shoe 18 is shown provided with an insulating button 20 which is arranged to lift a. contact spring 21 out of contact with a contact piece 22 when the shoe 18 is raised.

The apparatus of the train control system carried on the train is controlled by a control relay 23 having three armatures 24, 25 and 26 arranged to open and close certain controlling circuits hereinafter set forth. The energy for operating the apparatus on the train is derived from a suitable source of current, as a battery 27, carri-ed by the train.

The means for establishing or determining the permissive speed for the train at the different points in its travel and the means for determining the actual speed of the train are operatively connected to the wheels of the train, preferably to the axle of a pair of wheels which are neither driven nor braked. In the construction shown, a beveled gear 28 is keyed to the axle 15, and this beveled gear 28 meshes with another beveled gear :19 fixed to a shaft 30, which is journaled in suitable supports 81. To the shaft 30 is secured a bifurcated member 32, and pivoted to the outer end of each of the bifurcations of said memberBQ is av weighted arm 33, which has secured thereto a toothed sector 84. Mounted loosely on the shaft 30 is a sleeve 35, which has teeth 36 arranged and adapted to cooperate with the teeth of the sector 34, and which isprovided with two collars 37, between which is mounted a loose collar or sleeve 88. An arm 39 is pivoted between its ends upon a fixed pin or shaft- 40 and is pivotally secured at one of its end to the sleeve 38, the

extension of said arm 39 beyond its pivot axis being designated 39 To the end of the shaft 30 is fixed a bifurcated and an enlarged head 41, between which and the outer collar 37 is interposed a compression coil spring 42. Pivotally connected to the bifurcations of the head 41 is a pin 43, which is pivotally connected to the forked ends of an auxiliary shaft 44. The head 41 and the pin 43, together with the pivotal connections between said parts, form a universal coupling for connecting the shaft 30 and the auxiliary shaft 44.

Fixed to the auxiliary shaft 44 is a worm gear 45, and adjustably mounted on the outer end of said shaft 44 is a counterweight 46. The auxiliary shaft 44 is arranged to be attracted upward by an electromagnet 47, hereinafter termed the cam-starter magnet. A worm sector 48 is secured to a shaft 49 journaled in suitable bearings (not shown) in position to have its teeth cooperate with the teeth of the wornti gear 45, when the auxiliary shaft 44 is disengaged from the cam-starter magnet 47 and is in its lower position. The worm sector 48 is formed with a laterally projecting sector 50 having abrupt shoulders at each end; and loosely journaled on the shaft 49 are two weighted arms 51 positioned so as to engage the shoulders of the sector 50, fixed stops or rests 52 being arranged to limit the clownward movement of said weight-ed arms 51. A cam 53 is secured to the shaft 49 so as to rotate therewith in correspondence with the worm sector 48. The factors determining the shape of the cam 53 will be pointed out hereinafter in the description of the oper ation.

An arm 54 is journaled upon the shaft or pin 40 and carries at its upper end a roller 55, said arm 54 being arranged to swing in the same plane as the cam 53, so that in certain positions of the arm 54 the roller 55 will engage the cam surface or edge of said cam 53. The arm 54 extends below its pivot axis, the extension being designated 54 and secured in the extension 39 of the arm 39 and in the extension 54 of the arm 54 are two contact pins 56 which are arranged to make electrical contact with each other when the upper ends of the arms 39 and 54 are fully separated by the spring 58, said pins 56 being insulated from the respective extensions 39 and 54 Also secured in and insulated from the extensions 39 and 54 are two contact springs 57, which make contact with each other when the upper ends of the arms 54 and 39 are fully separated, as shown, and also after said arms have been pressed together for a short distance.

In this automatic train control system it is assumed that the train or vehicle is equipped with the ordinary type of pneumatic brakes which includes the usual train pipe 61. The construction and operation of the pneumatic system of brakes is well known, and it is deemed unnecessary to describe the construction and operation of this system in detail, it being sufficient for a clear understanding of this invention to know that the brakes are automatically applied on the train when the train pipe 61 is vented. In the train pipe 61 is inserted a suitable valve (50, which is operated by a solenoid 59, said valve 60, in the particular construction shown, being closed when the solenoid 59 is energized and being opened by the pressure in the train pipe 61, a spring or other means when said solenoid 59 is deenergized. The automatic train control system is also preferably provided with a warning signal, which in this instance is shown as a whistle 62, which is operated by compressed air supplied from the train pipe 61 through a pipe 63. A suitable valve (not shown) is inserted in the pipe 63 to control the communication between said pipe and the whistle 62, and this valve is designed to be operated by a suitable electromagnet 64, which in the construction shown holds said valve closed when energized and permits said valve to be opened by a spring or other means when deenergized.

The worm sector 48 and the cam are moved to different positions by a lever 65, which is pivoted at one end to a fixed pin 66, and is pivotally connected at its other end to a worm sector 48 by a pivoted link 67. The lever 65 is operated by two soleloo noids'68 and 69; and the core 70 of one of said solenoids 68 is pivotally connected to the lever near its pivot 66, the core 71 of the other solenoid 69 being bifurcated at its upper end and straddling the lever 65 and being provided with a pin 72 extending across the bifurcations of said core '71 above. the lever 65. The pin 72 of the core 71 of the solenoid 69 engages the lever 65 at a greater distance from its pivot 66 than the distance between said pivot 66 and the pointof connection of the core of the solenoid 68 with said lever. Each of the solenoids 68 and 69 has a pivoted armature 73 and 74. re-

spectively, which are shown according to established convention and which are raised to their upper position when said solenoids are energized.

The selector comprises a suitable plate 75.

' which for simplicity is assumed .to be made of insulating material. and which is preferably supported upon the front axle 13 and is enclosed in a suitable easing. Mounted on the plate 75 are three plungers or tappets 5 76, 77 and 78, which extend through suitable guides 79 secured to or integral with the plate 75. a transverse pin 80 in each of said plungers being arranged to engage the upper guide 79 for that plunger and thereby limit the downward movement of said plunger. A compression spring 81 surrounds each plunger and bears at one end against a collar 82 pinned thereto and at its other end against the upper guide 79. The plungers 76. 77 and 78 have secured thereto contact pieces 83, 84 and 85, respectively, which are positioned to cooperate and make electrical contact with three pairs of contact springs 86-87, 88-89 and 9091, respectively. These pairs of contact springs are connected by suitable conductors to the solenoids 68 and 69, but these conductors, as well as the other conductors connecting the different; parts of the train control system carried on thetrain, will not be described in detail. since these conductors and the operating (l1 cuits will be set forth hereinafter in the description of the operation.

Operation: The parts of the apparatus carried on the train are shown in the drawing in their normal positions. in which the trains may proceed unrestrained by the speed control apparatus. except for a limitation upon the maximum speed it may attain at any time, which is hereinafter explained. Vhen the parts are in their normal positions, the control relay 23 is energized by current supplied from the local battery 27 along a circuit, which may be traced as follows:

Circuit number one.

From the battery 27, conductors 92, 93

and 94, armature 24; of the control relay 23 in its upper position, conductors 95 and 96,

control relay 23, conductors 97 and 98, contact spring 20, contact piece 22, and conductors 99 and 100 back to the battery 27.

hen the control relay 23 is energized and its armature 25 is in its upper position, a proceed signal, which is shown as a green lamp G. is operated by a circuit which may be traced as follows:

Cirmlif number two.

From the battery 27, conductors 92 and 101. armature 25 of the control relay 23 in its upper position, conductor 102, green lamp G, and cmiductors 103. 104, 10 106 and 100 back to the battery 27.

\Vhen the control relay 23 is energized and its armature 26 is in its upper position, the cam starter magnet 47 is supplied with current from the battery 27 along a circuit which may be traced as follows:

Circuit number three.

From the battery 27, conductors 92, 93, 107. 108 and 109. cam starter magnet 17, conductor 110, armature 26 of the control relay 23 in its upper position, and conductors 111, 106 and 100 back to the battery 27.

\Vhen the parts are in their normal positions the solenoid 59 which controls the brake valve 60 is energized to hold said valve 60 closed. the circuit for said solenoid 59 being as follows:

Circuit number four.

Battery 27, conductors 92,93, 107, 108, 112, and 118. solenoid 59, conductor 119, contact springs 57 and conductors 120, 116, 117, 104, 105, 106 and 100 back to the battery 27.

Also, when the parts are in their normal positions, the electromagnet 64 for controlling the whistle 62 is energized. the circuit therefor being traced as follows:

Circuit member five.

From the battery 27. conductors 92, 93, 107, 108, 112 and 113. electromagnet 64. conductor 114, contact pins 56, and conductors 115, 116, 117. 104, 105, 106 and 100 back to the battery.

llaving described generally the construction and arrangements of the parts of an automatic system for controlling the speed of railway trains embodying the invention, and the controlling circuits for the apparatus on the train, the operation of the system as a whole will be described for a few cases in which certain trafiic conditions, such as may occur in practice, are assumed to exist.

For the first condition of traffic to be considered, assume that the train in question is at the end of the block A, and about to enter the block B; that said train has found the trackway unobstructed and has been running unrestrained by the speed control apparatus; and that neither the blocks B nor C are occupied by another train. Since neither the blocks B nor are occupied by a train, their respective track relays and 5 are energized from the corresponding track batteries a, and the armatures of said track relays are in their upper positions, as shown. Whenthe shoe 18 of the train engages the ramp R, the shoe 18 is raised and also makes electrical contact with said ramp. The raising of the shoe 18 pushes the coin tact spring 20 out of contact with the contact piece 22 so as to interrupt the normally closed circuit number one for energizing the control relay 23; and the electrical contact between the shoe 18 and the ramp R completes a circuit for energizing the control relay 23 which may be traced as follows:

Circuit number sz'a'. Commencing at the ramp R, conductor 121,

armature 8 of the track relay 5 in its upper position, conductor 122, battery 11, conductors 123 and 12 1, battery 10, conductor 125, track rail 1, thence through the Wheels and axles to the frame 16, conductors 126 and 96, control relay 23, and by conductors 97 and 12? to the shoe 18 and back to the ramp R.

As the train proceeds and the first pair of wheels 12-12 and axle 18 enter the block B, the track relay 5 is deenergized and its armature 8 drops and interrupts the circuit number six. \Vhen the armature 8 of the track relay 5 drops another circuit for energizing the control relay is set up as follows:

Circuit om'mber seven.

Commencing at the ramp R, conductor 121, armature 8 of the track relay 5 in its lower position, conductor 128, armature 9 of the track relay 5 in its upper position, conductors 129 and 122?, battery 10 conductor 125 to the track rail 1, thence by the wheels and axle to the frame 16, conductors 126 and 96, control relay 23, and by conductors 97 and 12'? to the shoe 18 and back to the ramp R.

The armatures of the control relay 23 being raised, the sn'iall current derived from the battery 10 alone is sufficient to hold said armatures in their upper position. This characteristic of the control relay 23, whereby its armatures will not be raised when the sinall current derived from the battery 10 alone flows through the coil of said relay, and whereby the arinatures of said relay will be held in their raised position by this small current, may be obtained in a number of different ways, all well known in the art, and it is deemed unnecessary to show and describe the specific construction of the con trol relay 28. a

When the shoe 18 leaves engagement with the ramp R, it is forced downward by its weight and the spring 19 to follow the gradual downward slope of the end of the ramp it, so that the contact spring 20 remakes contact with the contact piece 22 before the shoe 18 leaves electrical contact with the ramp, thereby reestablishing circuit number one before circuit number seven is broken.

From the foregoing it can be seen that when the train enters the block B, and when the blocks B and C are not occupied by another train, the parts of the speed control apparatus on the train are not affected and remain in their normal position.

For the next condition of tratfic to be considered, assume that the train in questionis in the block A and about to enter the block B; that this train has found an unobstructed trackway and has been traveling unrestrained by the speed control apparatus; and that while the block B is not occupied by another train, there is a train in the block C. Under these conditions, while the track relay 5 of the block B is energized, the track relayo of the block C is deenergized. When the shoe 18 engages the ramp R and before the first pair of wheels and axle of the train enter the block B, the circuit number six hereinbefore traced, will be established; but when the first pair of wheels and axle of the train pass into the block 13, said circuit numher six is interrupted by the deenergization of the track relay 5 and the dropping of its armature 8; and since the circuit number seven is interrupted by reason of the fact that the armature 9 of the track relay 5 is in its lower position, no current is supplied from any of the batteries along the trackway to the control relay 23. Also, the circuit number one for normally energizing the control relay 23 is broken by reason oi the fact that the shoe 18 is raised; and consequently the relay 23 is cut off from all sources of the supply of current, and its armatures 24:, 25 and 26 drop.

The dropping of the armature 2d of the control relay 28 opens break in the circuit number one, which normally energizes the control relay 23 when the shoe 18 is in its normal or lower position, so that, when the shoe 18 leaves contact with the ramp It and returns to its lower position, nevertheless, the circuit number one Will not be ree tablished. The dropping of the armature 25 breaks the circuit number two, which causes the green lamp G to be lighted, and also closes a circuit for lighting the yellow lamp Y, said circuit being as follows:

Circuit number eight.

From the battery 27, conductors 92 and 101, armature 25 of the control relay 28 in its lower position, conductor 150, yellow lamp Y, and conductors 151, 105, 106 and 100 back to the battery 27. i

The dropping of the armature 26 of the control relay 23 interrupts circuit number three, which normally energizes the cam starter magnet 47, and when the cam starter magnet 47 ceases to pull upon the auxiliary shaft 44, the counterweight 46 on said shaft pulls said shaft to its lower position and rings the teeth of the worm gear 25 into mesh with the teeth of the worm sector 48. The auxiliary shaft 44 is connected to the axle 15 0f the vehicle or train, and as the train proceeds along the track the worm sector 48 and the cam 53 are turned in the direction indicated by the arrow X, the lefthand weighted arm 51 being lifted at the same time.

The shape of the cam 53 is determined from the braking curve of the train which carries the cam, this braking curve, well known to those skilled in the art of braking trains, being found for each particular type of train and braking equipment by calculations, actual tests and the like. This braking curve of the train may be said to represent for each speed of the train the distance required to bring the train to a stop by its brakes; or, in other words, from the braking curve it is possible to determine for each point in the travel of the train how fast the train can be moving at that point and yet be brought to a stop by its brakes before another certain point is reached. In the particular kind of cam shown, the lengths of the radii of said cam represent different speeds, and the angular displacement of said cam represents different distances traveled by the train; and in effect, the cam represents a predetermined functional relation between the speed of the train and the distance traveled by the train. The effective action of the cam 53 takes place along the line of movement of its follower, namely, the roller 55 of the arm 54, which line of movement is the arc of a circle having its center at the axis of the shaft or pin 40 on which the arm 54 is journaled, this are of the line of movement of the roller 55 being indicated in the drawing by a dash line designated 1/. The radius of the cam 53 to the point where this are g intersects the edge of the cam, represents proportionately the permissive speed for the train at the point in its travel corresponding to the angular displacement of the cam at that instant. It is to be understood that the cam 53 will be of a different shape for different types of trains having different braking equipments; and that while the shape of the cam 53 shown in the drawing illustrates in a general way the shape of a practical cam, it should be understood that the shape of the cam 53 shown is not quantitatively precise.

The actual speed of the train is represented by the position of the arm 39, which is shown in the drawing in its position of zero speed. As the shaft is turned by the axle of the train to which it is connected, the weighted arms 33 are thrown outwardly by centrifugal force and the cooperation of the teeth on the sector 34 fixed to these arms 33 with the teeth 36 on the sleeve causes the sleeve 35 to move lengthwise of the shaft 30 against the opposition of the spring 42. The operation of the weighted arms 33, the sleeve 35 and the spring 42 is similar to that of the well known centrifugal governor. As the sleeve moves, it carries with it the upper end of the arm 39, and the spring 58 between the arm 39 and the arm 54 causes the arm 54 to take a corresponding movement. The parts are shown so proportioned that when the actual speed of the train, represented by the movement of the arms 39 and 54, is nearly as great as the permissive speed prescribed by the cam 53, the roller 55 of the arm 54 will touch the edge of the cam 53. As the cam 53 is turned by the worm gear 45 and the worm sector 48 in the direction of the arrow X, the radii of the cam increases proportionately to the functional relation between the distance traveled by the train and the permissive speed for the train, determined from the braking curve; and, consequently, the roller is forced toward the right by the edge of the cam 53. As the arm 54 is moved to the right by the cam 53, unless the actual speed of the train is reduced correspondingly so as to permit the arm 39 to move to the right the same amount, the spring 58 will be compressed and the lower extensions 54 and 39 of the respective arms 54 and 39 will be moved farther apart. The first slight movement of the extensions 54 and 39 apart from each other, which will result if the actual speed of the train approaches closely to the permissive speed for the train, draws the contact pins 56 out of contact with each other so as to break the circuit number five which normally energizes the electromagnet 64 and which normally retains the warning signal or whistle 62 inactive, thereby causing said warning signal to sound. The sounding of the warning signal 62 informs the engineer or motorman of the train that the speed of the train is too high and that he should apply the brakes at once. If the engineer obeys the warning signal and reduces the speed of the train to a safe amount below the permissive speed for the train prescribed by the cam 53, the arm 39 will move far enough to the right to permit the contact pins 56 to again contact with each other, whereupon the circuit number live will be reestablished and the whistle (32 will cease to sound, thus informing the engineer that he has been successful in reducing the speed of his train to a safe speed. In this way, in a system embodying this invention, a warning signal is sounded whenever the actual speed of the train approaches too near the safe permissive speed for the train.

If the engineer should be incapacitated, or should carelessly fail to reduce the speed of his train in obedience to the warning signal, the arms 54 and 39 will be moved closer together and cause the lower extensions 54 and 39 to move far enough apart to bring the contact springs 57 out of contact with each other, thereby breaking the circuit number four which normally energizes the solenoid 59 and holds the valve in the train pipe (51 closed, so that said valve (30 is opened by the pressure in the train pipe or by a spring to vent the train pipe 61 and cause an automatic application of the brakes. Suitable means, which, being well known in the art, is not illustrated, is preferably employed to prevent the engineer or inotorman' from opposing the automatic application of the brakes, and this means may be arranged to prevent the brakes from being released until the train is brought to an absolute stop, or this means may be arranged to permit the brakes to be released as soon as the actual speed of the train has fallen a certain amount below the permissive speed of the train.

From the foregoing it can be seen that when the train enters the block B, while the block C is occupied by another train, certain effects are produced. as follows: First, a caution signal, which in this instance is the yellow lamp Y, is operated; second, a warning signal is sounded as soon as the actual speed of the train approaches close to the permissive speed for the train; and third, if the warning signal is disregarded and the actual speed of the train approaches too close to or exceeds the permissive speed for the train, the brakes for the train are automati cally applied. In any event, the train will be brought to a stop or to a safe low speed by the time it reaches the end of the block B, either by the engineer or inotorman, or automatically by the train control apparatus.

For the next condition of traffic to be con sidered, assume that the train in question is in the block B and has had its speed controlled by the train control apparatus in the same way as hereinbefore described; and further assume that the other train which formerly occupied the block C moves entirely from the block G into the block I) before the following train reaches the end of the block 13. lVhen the shoe 18 of the fol lowing train contacts with the ramp R at the entrance to the block C and before the first pair of wheels and axle of said following train enter the block C. the two batteries 10 and 11 will energize the control relay 23, although it is deenergized, becc use of a circuit number nine which can be easily traced by analogy to circuit number six hereinbefore traced. The energization f the control relay E23 raises its armature 26 and reestablishes circuit number three 'ingly located along the trackway.

for the cam starter magnet 47; and the cam starter magnet 47, being energized, lifts the auxiliary shaft 4% and draws the worm gear 45 out of mesh with the worm sector 48, whereupon the weighted arm 51 returns the worm sector 48 and cam 53 to their normal positions. Thereafter, when the first pair of wheels and axle of the train enter the block C, the control relay 23 will be again deenergized by reason of the fact that another train occupies the block 1); and this deenergization of the control relay 23 sets the cam 53 into operation again in the same manner as hereinbefore described. In this way, the cycle of operation of the train control apparatus is commenced again at the entrance to the block C.

The parts of the system, the operation of which has been described, will work satisfactorily for railways where the blocks are all of the same length; but, as pointed out in the preliminary discussion, in practice the different blocks of a railway vary in length. Obviously, a train entering a long block need not commence to reduce its speed as soon as it would in entering a short block at the same speed, and if compelled to do so by the train control apparatus, the trainis unnecessarily delayed. For this reason, suitable provision is made in the system embodying this invention for moving the cam 53 to different positions according to the different lengths of the blocks; and while this movement of the cam 53 may be accomplished in various ways, in the particular construction shown, the cam 53 is moved to different positions by selectively energizing the solenoids 68 and 69 by selectively operating the selector tappets or plungers 7 6 or 78 by means of selector ramps correspond' In the particular arrangement shown, the space be tween the track rails 1 and 2 is divided equally to furnish space for three separate rows of selector ramps, the ramps in the row nearest the track rail 2 being designated SL, the selector ramps in the middle row being designated SC, and the selector ramps in the row nearest the track rail 1 being designated SR. The particular location of the selector ramps in the length of the blocks will be discussed later after the operation of the selector ramps and corresponding parts on the train operated thereby is made clear. v

Assuming that a train is passing from the block B into the block 0 and disregarding for the moment the action of the middle selector ramp SC at the entrance to the block C, when the front axle 13 of the train carrying the selector tappets 76, 77 and 78 passes the selector ramp SL, the corresponding selector tappet 76 is raised to bring the contact piece 83 carried thereby into contact with the pair of contact springs 86 and 87,

thereby completing a circuit for energizing the solenoid 68, as follows:

Circuit number ten.

Commencing at the battery 27, conductors 92, 93, 107, 130 and 131, contact spring 87, contact piece 83, contact spring 86, conductors 132 and 133, solenoid 68, and conductors 134, 135, 117, 101, 105, c and 100 back to the battery :27.

The energization of the solenoid 68 attracts its core 70 and swings the lever 65 downwardly, thereby moving the worm sector 48 and the cam 53 in a direction opposite to the direction indicated by the arrow X, the righthand weighted arm 51 being lifted at the same time. This movement of the cam 53 places it in position so that it will have to be turned farther before it indicates for the arm 54 a. zero or a low permissive speed; and in this way, the cam-53 is made to correspond to a longer block. When the solenoid 68 is energized, the armature 73 controlled thereby is raised to its upper position, thereby closing a circuit which maintains the solenoid 68 energized after the tappet 76 leaves engagement with the selector ramp SL and under the impulse of the spring 81 moves downward and opens the circuit number ten here nbefore traced. This maintaining circuit for the solenoid 68 is as follows:

Circuit number eleven.

Commencing at the battery 27, conductors 92, 93, 107, 130 and 139, contact spring 88, contact piece 84 of the selector tappet 77, in the lower position of said tappet, contact spring 89, conductors 138 and 137, armature 73 in its upper position, conductors 136, 133, solenoid 68 and conductors 134, 135, 117, 104, 105, 106 and 100 back to the battery 27.

Since it is assumed that a train occupies the block D, the cam starter magnet 47 will be deenergized in the same way as hereinbefore described and the auxiliary shaft 41 will drop under the influence of the counterweight -16 to bring the worm gear 45 into mesh with the worm sector -18, whereupon the cam 53 is moved in accordance with the distance traveled by the train, and in the same way as hcreinbefore described compels the speed of the train to be reduced so as to; bring the train to a stop or to a safe ow speed before the train reaches the end of the block C. This movement of the cam 53 is made against the opposition of the solenoid 68, but this will ordinarily cause no damage: and, if desired. the maintaining circuit number eleven for the solenoid 68 may be made dependent upon the movement of the auxiliary shaftl i, in a way which will be apparentto those skilled in the art of railway signaling, so that when said auxiliary shaft 44 drops, said maintaining circuit: number eleven will be interrupted. In the arrangement shown, the maintaining circuit number eleven for the solenoid 68 is controlled by the middle selector tappet 77, and said solenoid 68 will remain energized until the train passes the next middle selector ramp SC. When the middle selector iappet 77 engages the middle selector ramp 5C, it is lifted to move the contact piece 84 out of contact with the contact springs 88 and 89, thereby interrupting the maintaining circuit number eleven for the solenoid 68.

The same operation takes place as the train enters the block D, which is assumed to be longer than the block B, but not as long as the block C, and which corresponds to the position of the cam 53, to which it is operated by the solenoid 69. When the train passes the selector ramp SR, the righthand selector tappet T8 lifted to bring the contact piece carried thereby into contact with the contact springs 90 and 91, thereby closing a circuit for energizing the solenoid 69, which circuit may be traced as follows:

Circuit number twelve.

Commencing at the battery 27, conductors 92, 93, 107. 130 and 140, contact spring 90, contact piece 85, contact spring 91, conductors 1-11 and 142, solenoid 69 and conductors 113, 35, 117, 104-, 105, 106 and back to the battery 27.

The maintaining circuit for the solenoid 69 is as follows:

Circuit number thirteen.

Commencing at the battery 27, conductors 92, 93, 107, 130 and 139, contact spring 88, contact piece 84, contact spring 89, conductors 138 and 115, armature 74 in its upper position, conductors 141 and 1-12, solenoid 69, and conductors 113, 135, 117, 101, 105, 106 and 100 back to the battery 27.

In the system embodying this invention, there is also a limitation imposed upon the maximum speed which the train may attain at any time, regardless of whether the train is proceeding under a clear proceed signal or under a caution signal. This maximum speed limitation results by reason of the fact that when the cam 53 is stationary, the arm 51 may be moved a certain distance toward the left by the arm 39 in corrcspomlence with the actual speed of the train before the roller 55 strikes the edge of said cam: but if the arm 39 is moved further toward the left because of an increase in the actual speed of the train. the extensions 39 and 51 will be moved apart, since the arm 54 is held from further movement toward the left by the cam 53: and this movement of the extensions 39 and 51 apart from each other will cause a separation of the contact pins 56, thereby causing the sounding of the warning signal; and a. still further movement of said extensions apart from each other, corresponding to a further increase in the actual speed of. the train, will cause the contact springs 57 to separate andthe brakes to be automatically applied; In this way, although the train-may be traveling under a full proceed signahthe actual speed of the train cannot be increased beyond a certain n'laximum speed prescribed by the cam 53 in the position which it then occupies. It is apparent that by energizing either the solenoid 68 or the solenoid 69 the position of the cam 53 may be changed so as to change the maximum speedlimitation for the train under a proceed signal. Further, it is apparent that, for the purpose of controlling the speed of a train under a proceed signal, suitable permanently deenergized ramps may be placed at diiferent points along the trackway other than at the entrances to the blocks, as for instanceatdangerous curves and the like, and these rampsowill cause the cam starter magnet at? to be deenergized and thereby set the cam 53 into motion to require the. actual speed of the train to be reducedto a certain amount; and subsequently, when the train has traveled a distance such as to move the cam 53 to a position corre sponding to a safe permissive speed, permanently energized ramp may be placed which will effect a re-energizat-ion of the control relay 23 and the release of the cam 58.

Certain factors dependent upon the peculiar characteristics of the train controlsystem shown and described'determine the location of the selector ramps; but it is to be understood that other arrangements of parts will modify the particular location of the se lector ramps shown and hereinafter described.

lhe effect of the middle selector ramp SC is to break the maintaining circuits numbers eleven and thirteen for the solenoids 68 and 69, so that, unless the worm gear is in mesh with the worm sector 48, the weighted arms 51 return the cam 53 to its normal position. The effect ofthe side selector ramps it and SL is to energize the corresponding; solenoid 68 or 69 so that, unless the worm gear 45 is in mesh with the worm'seetor i8, the cam 53 is shifted to a position to correspond. It should be noted that even if the worm gear 45 isin mesh with the worm sector d8, so as to prevent the energization of the solenoid 68 or from actually moving the cam 53, either of'these solenoids 58 or 69, when energized, raises its armature 73 or 74', although its core may not move, and this armature closes the circuits numbers eleven am thirteen for maintaining said solenoid energized until" arelease of the cam 53 per mits it to be effective to actually move the cam 53. One consideration for the location of the middle selector ramp SCfor each block may be-that, by placing this middle selector ramp near the exit end? of that block, the selection set up when the train entered that block will be held while the train is trayeling through that block and will serve to impose the proper maximum speed limitation required for that block. In some cases, this maximum speed limitation may be too high for the physical conditions existing in that block, and in such cases it may be necessary to locate the middle selector ramp SC near the entrance end of the block so as to release the cam 53 and allow it to return to its normal position. or to an? other one of its operated positions which may be set up simultaneously.

Whether or not a particular selection of the position of the cam 53 is to be used for controlling the speed of the train is determined shortly after the first pair of wheels and axle of the train enter the next block, whereupon the control relay 23 is either deenergized or kept energized according to the traffic conditions. The particular selection of the cam, however, should preferably be set up sometime before the first. pair of wheels and axle of the train enter that block which fits that position of the cam, that is, before the control. relay 23 would bedeen; ergized, if traific conditions were such that it should be deenergized'; otherwise, if the new selection is not made by this time, the deenergization of the control relay 23 would deenergize the cam starter magnet 47' and cause the worm gear l5 to drop into mesh with the worm sector 4L8 and prevent the movement of the cam 53 by the solenoid 68 or 69.

In controlling the positions of the cam 53 fordifterent lengths of blocks, it is considered preferable to place the selector ramps so that the following sequence of operation. will, in general, occur; first, the middle selector ramp SC is arranged to cancel the preceding selection; and this middle selector ramp may be located any distance ahead of the entrance of the block in question, providing' that it is not ahead of the pointwhere the control relay 23 on the train would be deenergized as the train entered the preceding block, if traffic conditions were such that said control relay should be deenergized. Second, the proper side ramp SR or SL for obtaining the selection desired is located at some point following the middle selector ramp, and ahead of the point where the control relay 23 on the train would be deenergized as the train enters the following block, if traffic conditions were such that said control relay should be deenergized. In short, if the point in each block at which the control relay 23 is deenergized as the train enters that block, providing traffic conditions are such as to require the deenergization of said control relay, is called the imaginary entrance to that block, the middle selector SC and the side selectors SR and SL may be located at any point between the imaginary entrances between two succeeding blocks.

There are a number of factors which determine the exact location of the selector ramps in the length of the different blocks, but oneexample will serve to illustrate how the different location of the selector ramps may be used to obtain significant changes in the control of the speed of the train, if desired. For instance assume the case where a short block, as the block l3, having a low maximum speed limitation, for a train traveling under a proceed signal is followed by a longer block, as the block C, which has a higher maximum speed limitation; and further assume that the conditions in the short block B are such that the train after it has proceeded for a short distance into that'block B can attain a much higher speed with safety than is permitted by the maximum speed limitation of that short block. Under these conditions it is apparent that it is preferable to locate the middle selector ramp SC and the corresponding side selector ramp SR or SL shortly beyond the entrance to the short block B, so that the vehicle shortly after it passes said entrance will be released from the lower maximum speed imposed by the position of the cam 53 for the speed control in the short block B, and will be allowed to accelerate to the higher maximum speed permitted by the maximum speed limitation of the succeeding longer block C. As another advantage of this last described arrangement, it may be noted that when a number of locomotives or motor cars, each equipped with the automatic train control apparatus embodying this invention, are in cluded in the same train, these locomotives or motor cars will pass the side selector ramp shortly beyond the entrance to the short block B, which is back far enough from the entrance to the longer block C as to ordinarily prevent the locomotives or motor cars in the rear part of the train, which have their cams in the position for the lower maximum speed, from unnecessarily delaying the movement of the train as a whole.

For another example illustratinghow the location of the selector ramps can be used to modify the control of the speed of the train,'assume that a long block, as the block C, having a high maximum speed limitation, is followed by a shorter block, as the block D, which has a lower maximum speed limitation; and further assume that the train in question may pass through the block C at unrestricted speed but must be brought to a stop or to a safe low speed by the time it reaches the end of the block D. Under these conditions the control of the train may be satisfactorily and safely accomplished within the limits of the shorter block D only in case the train enters this shorter block D at a speed not in excess of the maximum speed limitation for this block D, since the maximum speed limitation is automatically determined by the cam with reference to the length of the block D and the braking conditions therein. For this reason it is necessary to compel the speed of the train to be reduced to the lower maximum speed limitation for the block D at some point further back than the entrance to the block D, and this may be accomplished by locating the middle selector ramp SC in the block C so that itwill release the cam 53 and cause it to assume its normal position at a sullicient distance from the end of the block C that the resulting immediate application of the brakes would cause the speed of the train to be reduced equal to or less than that of the maximum speed limitation in the block D. In this way, unless the operator of the vehicle voluntarily reduces the speed of the train, while it passes through the block C, ready to meet the conditions in block D, the speed of the train will be automatically reduced. A side selector ramp, as SR, may be located in the longer block C in position to select the position of the cam 53 suitable for the block D at substantially the same time or subsequently.

The cam 53 is preferably arranged so as to be normally in the position suitable for the shortest block and lowest maximum speed, so that a failure of the apparatus to cause a movement of the cam to its other operated positions, corresponding to longer blocks and higher maximum speeds, will result in the train being controlled by the cam on the side of safety. Obviously, the cam 53 may be moved to any number of positions by providing additional solenoids, like the solenoid 68 and 69, additional selector tappets like tappets 7G and 78, and additional side selector ramps. Also, other movements of the cam 53 other than a simple rotation may be made in cases where it is found that the curve of speed and distance represented by the cam may be modified in this way to approximate more nearly the actual braking curve of the train under different braking conditions. Also, while the automatic train control system embodying this invention has been shown and described as designed to be operated by direct current, simple modifications, which will be apparent to those skilled in the art of railway signaling, may be made whereby alternating current may be used for the operating medium. Also, although one of the track rails, namely the track rail 2. is shown as divided into blocks by insulating joints 3, both track rails may be divided into blocks, if desired; and in cases where it is found desirable to use the track rails as a return for propulsion current, both track rails may be used as a return by conessence necting" suitable impedance bonds, Well lrnovvnjin' the art, to, thetraclt rails of adja'centvblooks. Various other modifications may be-madein the particular construction and control circuits shown and described without departing from the invention or from the particular physical embodiment thereofshown; and various features may be combined Wit-l1 this system Withoutdeparting from theinvention; as for instance, sev- QIiIl'lOCOHlOtZlVQS01"1110l301" cars each equipped with; the train control apparatus, may be combined into a train and provided With suitable electrical connections whereby some or all o'fthe parts of'the respective traincontrol apparatus may be operated simultaneously Although I "have particularly described the constructionot'one physical embodiment of my: invention, and explained the operation andprinciple thereof, nevertheless, I desire to have it understood-that the iorm'selected is merely illustrative, but does not exhaust the possible physical embodiments of the idea ofmeans: underlying my invention.

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

1-. In a system torxautomatically controlling the speed ofrailway vehicles, in combination: speed responsive means'on the vehicle operated in accordance; With the actual speed thereof; permissive speed means on the vehicle for establishing permissive speeds therefor and biased to assume a predetermined low speed initial condition; means selectively controlled at predetermined points along the traclrfor causing said permissive speed means to assume any one of a plurality of'other'high speed initial conditions; and means controlled by apredetermined cooperation of said speed responsive means and said permissive speed means for controlling the movement of'said vehicle. I I

2. In a system tor v automatically controlling, the speed-of railway vehicles, inconibination: a speed responsive device on the vehicle respondingto the, actual speed'thereof; a movable cam for establishing-permissive speeds for the vehicle and biased to assume a predetermined lllltlillPOSltlOl]; means gov ernedin accordance with trafiic conditions along the track and operable to move said cam' in correspondence With the distance travelled by the vehicle; means selectively controlled atpredetermined points along the track for moving said cam to any one of a plurality of other initial positions; and means responsive to apredetermined cooperationotsaid speed responsive device and saidcam for controllingthe movement of said vehicle.

3. In a system for automatically controlling the speedo'lf railway vehicles, in combination: a cam for establishing permissive speeds" for'theveliicle and movable from an existing initial position to impose decreasing permissivespeeds'; means controlled; at fixed points along thetrack for moving said cam'to any one of a plurality of different initial positions and thereby changing the maximum permissive speed established by saidcam; said cambeing biased to assume its-initial'position corresponding to the lowcst maximum permissive speed; and means for; retarding the movement of said vehicle when its actual speed exceeds-the permissive speed prescribed by the position of the cam.

4; In a system. for automatically control ling the" speed of trainson railroad tracks divided intobloclrs having normally closed track circuits, in combination: automatic speed control apparatus on the vehicle including a unitary permissive speed means acting in conjunction with other elements to determine the various speeds at which the vehicle may travel, said permissive speed means havingdifi'erent initial conditions determining ditlerent maximum speeds-for the vehicle and'a'lso being-adaptedcwhen set into operation to change gradually from the existing initial condition to successively lower speed conditions; means partlyon the vehicle and partly along the track for governing said permissive speed means toselect the initial condition therefor; and means partly on the vehicle and partly along the track controlled by the trackcircuits of blocks for governing theoperation of said permissive speed means.

5. In a system for automatically controlling thespeed ofrailway vehicles, in combination; permissivespeed means for establishing permissive speeds for the vehicle and having an initial maximum speed condition which it constantly tends to assume; electromagnetic devices lion causing said permissive speed means to'assume any one of a plurality of other initial maximum speed conditions; cooperating devices carried by the vehicle and located along the track for selectively controlling said-electromagnetic devices; and means for retarding: the movement of said vehicle When its actual speed exceeds the permissive speedprescribed by said permissive speedmeans.

6. In a system for automatically controlling the speed of railway vehicles, in combination: a permissive-speed cam; means for moving said cam in accordance With the distance traveled by the vehicle; cooperating devices-carriech by the vehicle and located alongthe trackfor controlling-said means in accordance with traiiic conditions; a plurality of'electroinagnetic devices for moving said-cam to different initial positions; a controlling-circuit for each of said electromagnetic devices; and means partly on the veliicle and partly alongtlie-track for governingthe said circuits selectively.

till) 7. In a'system for automatically controlling the speed of railway vehicles, in combination: means responding to the actual speed of the vehicle; a permissive speed cam biased to assume a predetermined initial position; means operable to move said cam from its existing initial position to successively lower speed positions in accordance with the progress of the vehicle along the track; means responsive to a predetermined cooperation of said first mentioned means and said permissive speed cam for controlling the movement of the vehicle; electromagnetic devices for moving said cam to any one of a plurality of other initial positions; and cooperating devices carried by the vehicle and located along the track for selectively controlling said electromagnetic devices.

8. In a system for automatically controlling the speed of railway vehicles, in combination: automatic speed control apparatus on the vehicle including a permissive speed means adapted to assume diiferent initial conditions determining difierent maximum permissive speeds for the vehicle and also adapted when set into operation to change gradually from an existing initial condition to successively lower speed conditions; means tending to cause said permissive speed means to assume a low speed initial condition; and means partly on the vehicle and partly along the track for governing said permissive speed means to cause it to assume higher speed initial conditions at predetermined points along the track.

9. In a system for automatically controlling the speed of trains on railroad tracks divided into blocks each having a normally closed track circuit, in combination: automatic speed control apparatus on the vehicle including a permissive speed means adapted to assume different initial conditions determining difierent maximum permissive speeds for the vehicle and also adapted when set into operation to change gradually from the existing initial condition to successively lower speed conditions; means partly on the vehicle and partly along the track for governing said permissive speed means to select its initial condition; and means partly on the vehicle and partly along the track controlled by the track circuits of the blocks for governing the operation of said permissive speed means.

10. In a system for automatically controlling the speed of railway trains on tracks divided into blocks of different lengths each having a normally closed track circuit, in combination: a unitary permissive speed device on the vehicle adapted to assume different initial conditions corresponding to the different lengths of blocks; means operable at predetermined points along the track for governing the said device to select the required initial condition thereof; and means associated with each block and responding to hicle; means operable to move said cam from its existing initial position gradually to suecessively lower speed positions in accordance with the progress of the vehicle along the track; trackway devices for selecting the initial position of said cam; and other trackway devices responsive to trallic conditions in the blocks for governing the operation of said means.

12. In a system for automatically controlling the speed of railway vehicles, in combination; automatic speed control apparatus on the vehicle including a movable cam adapted to assume any one of a plurality of different initial positions, said cam being biased to assume its lowest speed initial position; and means partly on the vehicle and partly along the track for automatically and selectively moving said cam to its higher speed initial positions.

13. In a system for automatically controlling the speed of railway vehicles, in combination: automatic speed control apparatus on the vehicle including a unitary permissive speed element adapted to assume ditlen ent initial conditions; means tending to cause said permissive speed element to assume a predetermined maximum speed initial condition; a number of electromagnetic devices each operable to cause said permissive speed element to assume a distinctive initial condition difl'erent than said predetermined maximum initial condition; circuits for controlling said devices; and means partly on the vehicle and partly along the track for selectively controlling said circuits.

14. In an automatic train control system "for railroads having tracks divided into blocks of different lengths each provided with a normally closed track circuit, automatic speed control apparatus on a railway vehicle including a permissive speed element adapted to change gradually from a maximum permissive speed condition to an ultimate minimum speed condition during the progress of the vehicle through a block, means tending to cause said element to assume an initial maximum speed condition corresponding to a short block, means effective at predetermined points with reference to the entrance to longer blocks for causing said element to assume higher maximum speed conditions corresponding to the length of such blocks, and means controlled by the track circuits of said blocks for causing said permissive speed element to commence its gradual change from itsthen existing maxi mum speed condition at the entrance to each block when the neXt block in advance is occupied.

15. in an automatic train control system for railroads having tracks divided into bloclrs each provided with a normally closed track circuit, automatic speed control apparatus on a railway vehicle including a per missive speed device having a plurality of initial maximum speed conditions and adapted to change from its existing initial condi: tion and impose lower permissive speeds at successive points in the progress of the vehicle through a block, means effective to adjust said device quickly to any one oi its initial maximum speed conditions, and means partly on the vehicle and partly along the track for governing said means to selectively determine the initial condition to be assumed by said permissive speed device.

16. in an automatic train control system for railroads having tracks divided into blocks of difi'erent lengths each provided with a normally closed track circuit, speed control apparatus on a railway vehicle including a permissive speed device capable of operating to impose permissive speeds for the vehicle varying from a maximum to a minimum, said device having a tendency to impose an intermediate permissive speed, means for adjusting said device to impose permissive speeds higher than said intermediate permissive speed, and means adapted to be governed in accordance with trailic conditions for governing the operaion of said device.

17. in an automatic train control system tor railroads having tracks divided into blocks each provided with a normally closed track circuit, speed control apparatus on a railway vehicle including'a speed-responsive device governed by the actual speed of the vehicle, a changeable permissive speed element adapted when set into operation to change from its existing initial condition and establish decreasing limiting permissive speeds for the vehicle, electro-responsive means on the vehicle adapted to be influenced by trackway devices for quickly adjusting said permissive speed element to any one of a plurality of diiferent initial conditions, and brake controlling means governed jointly by said speed-responsive device and said permissive speed element.

18. in an automatic train. control system for railroads having tracks divided into blocks each provided with a normally closed track circuit, speed control apparatus on a railway vehicle including a speed-responsive device governed by the actual speed thereof, a changeable permissive speed element capable of assuming different initial conditions and adapted when set into op eration to change gradually during the progress 01' the vehicle and establish decreasing limiting permissive speeds for the vehicle, electro-responsive'means on the vehicle adapted to be influenced by trackway devices for quickly adjusting said element to anyone of a plurality of diiierent initial conditions, a warning signal arranged to give an arrestive indication to the operator of the vehicle, a brake setting appliance, and means responsive jointly to said speed-responsive device and said permissive speed element for operating said warning signal and said brake setting appliance with an intervening interval of delay.

19. In an automatic train control sys: tem for railroads having tracks divided into blocks of different lengths each provided with a normally closed track circuit, automatic speed control apparatus on a railway vehicle including a movable cam for establishing various permissive speeds for the vehicle and adapted to assume any one of a plurality oi different initial positions, control means on the vehicle adapted to be influenced by traiiic controlled trackway devices for causing said cam to be gradually moved by the wheels of the vehicle from its existing initial position and thereby estab lish gradually decreasing permissive speeds, and other means partly on the vehicle and partly along the track for shifting said cam at a predetermined point with reference to the entrance to each block to an initial position corresponding with the length of that block.

20. In an automatic train control system, speed control apparatus for railway vehicles including a movable permissive speed element, mechanism for shifting said element to different positions comprising a plurality of electro-magnets operatively connected to said element and each adapted to move it to a predetermined position, pickup and stick circuits for said electromagnets, and means adapted to be intluenced by traclrway devices for selectively controlling said circuits.

21. In combination, a railway vehicle, ve-

hicle controlling means thereon, means on the vehicle for controlling said vehicle controlling means comprising a speedcontrolled means and a speed limit cam capable of being set for any one of a plurality of speeds, means spaced along the trackway for setting said speed limit cam for a determined speed, and other means along the t-rackway for operating said speed limit cam in accordance with tralllc conditions ahead.

winrinnor K. HOWE.

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