US1454513A - Automatic train-control system - Google Patents

Description

May 8, 1923.

'W. K. HOWE AUTOMATIC TRAIN CONTROL SYSTEM 2 Sheets-Sheet 1 Filed May 51, 1919 INVE T ATTORNEY.

May 8, 1923.

W. K. HOWE AUTOMATIC TRAIN CONTROL SYSTEM Filed May 31, 1919 2 Sheets-Sheet 2 EN R.

A TTORNEY Patented May 8, i923 WINTHROP K. HOWE, OF ROCHESTER, NEW YORK, ASSIG-NOR TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

AUTOMATIC TRAIN-CONTROL SYSTEM.

Application filed May 31, 1919. Serial No. 300,976.

To all whom it may concern:

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

This invention relates to automatic train control systems for railways, and more particularly to speed control systems in which the speed of the train is regulated at various points in its travel to accord with prescribed safe permissive speeds.

This invention contemplates a speed control system in which the speed of the train is limited to certain prescribed permissive speeds at different points in its travel; but instead of automatically applying the brakes in spite of the engineer whenever the actual speed of his train exceeds the safe permissive speed, this invention involves the provision of suitable means and appliances for exerting a tendency to cause an automatic brake application of .a character which the engineer may oppose, if occasion requires, and prevent such automatic brake application. In other words, the control of the train is not taken entirely out of the hands of the engineer, and although the automatic system acts to govern the train at all times in a. way best suited to the combined interests of safety ment, the englneer can exercise his judgment, when special conditions or emergencies require, to govern his train in such a manner as to avoid unnecessary delay. My system, therefore, is in a sense directed toward helping out the engineer, and is intended to safe-guard his train if he is incapacitated, preoccupied, or otherwise unable for any reason. to safely control his train himself. In this way the ultimate safety of a train is the result of the combined reliability and efficiency of the engineer and the automatic train control system; and it is contemplated that any deficiency of either the human element or the mechanical element will, to a large extent at least, be cured by the other, so that the desirable qualities of automatic mechanism will supplement the vigilance and care of the engineer, while the experience and skill of the engineer will in turn supplement any inade quacies of the automatic mechanism.

and facility of train move-- The speed control system which I preferably ernploy is of the type having a cycle of operation, that is, the speed control apparatus on the train after being set into operat on to reduce speed, will continue in operation until restored. For the purpose of restoring such a. cyclic type of speed control apparatus to its initial or maximum speed condition, after it has been-set into, operation, I preferably employ automatic means which acts as soon as said apparatus has attalned its ultimate minimum speed condition, thus obviating any complications in trackway circuits and car equipments involved in making the automatic restoration of the speed control apparatus dependent upon tratlic conditions.

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

For the purpose of disclosing the nature and characteristic features of my invention. I have illustrated in the accompanying drawings one embodiment of the invention, the apparatus and circuits being illustrated in a simplified and diagrammatic manner, more with the view of making it easy to understand the invention, than with the idea of showing the exact construction and arrangement of parts which would be preferably employed in practice.

In describing the invention in detail, reference will be made to the accompanying drawings, in which the same reference characters designate corresponding parts in the several views. and in which Figure 1 shows a portion of a railroad track equipped with the trackway circuits and trackway impulse devices of my system, together with some explanatory per-- missive speed curves; and

Fig. 2 illustrates the car equipment, and also shows the cooperative relation between the traclrway impulse element and the carcarried receiving element.

Referring to Fig. 1, the track rails 1 and 2 of the railroad track are divided by insulated joints 3 into blocks, as in ordinary block signal systems. Two blocks B and C, together with the adjacent ends of two other blocks A and D, are shown. In order to illustrate the manner in which my invention is applicable to the blocks of difierent length found in practice, the block B is assumed to correspond with the shortest block on the railroad, that is. one ap proximately equal to braking distance for the normal running speed. while the block C is typical of a block longer than such braking distance. Various combinations of differentlengths of blocks will, of course, occur in actual practice; but the same principles hereinafter explained in connection with the two blocks B and C can be applied to provide for any arrangement and number of blocks desired.

Since the various devices and circuits as: sociated with the several blocks are the same. these will be given the same reference characters with distinctive exponents as amatter of convenience. Each of the blocks is provided with the well known normally closed track circuit. comprising a track battery 4 and a track relay 5. My system of automatic train control is preferably used in connection with the usual fixed signals employed in the well known automatic block signal systems: and such signals S have been shown conventionally in Fig. l. The circuits and devices for controlling the indications and aspects of these fixed signals S, howeverfbeing well known in the art. have not beenillustrated to avoid unnecessary complication.

Associated with each block is a trackway impulse device T which adapted to cooperate with an impulse receiving element on passing trains to transmit the appropriate controlling impulses or influencesrequired to govern the train control apparatus on such train. furious types of impulse transmitting means may be enuiloyed in my system. and the particular means of the inductive type. herein shown and described. is merely illustrative. The track way element T comprises a U-shapcd mag:- netic yolte or core 6 with pole pieces '7 (see Fig. 2); and on each lee; of this yoke 6 is a coil 8. The trackway element T of each block is preferably located at service braking distance from the exit end of that block. with such additional distance for a margin of safety as desired. Thus. in the short block B, the trackway element T is located at the entrance to said block. whereas in' 8 ol each traokway clement T trative of a way in which the trackway elements T of the several blocks may be controlled so as to transmit a cautionary impulse at each caution signal and not transmit such impulse at a clear signal. Obviously, various modifications and adaptations of the trackway circuits illustrated may be employed. it being evident that various eX- pedients may be utilized to insure the opening and closing of the circuit for the coils 8 of the trackway element T of each block. depending upon traffic conditions in the next block in advance. Generally stated. the significant and characteristic feature of the trackway circuits employed in my system of train control is that the coils 8 of the trackway element T of each block are short-circuited under clear trafiic conditions. when the next block in advance is not occupied. and are open-circuited under (lain gerous traii'ic conditions. when said next block in advance is occupied.

The upper part of Fig. 1 also shows a number of permissive speed curves X for the several blocks. These curves are drawn conventionally to indicate the speed-distance curves of permissive speeds which the trains should observe in traveling through the successive blocks under dangerous trallic conditions. in these curves, the horizontal distances represent the travel of the train through the blocks. and the vertical distances. or ordinates. represent various speeds. it should be understood that these curves are merely typical and will neces sarily vary in practice with diii'erent equipments and on ditlerent railroads. The significance ot these curves will he explained hereinafter in the description of the operation.

Fig". 2 illustrates in a simplified manner the car equipment of a speed control system having a cycle of operation. this apparatus being of the type disclosed in detail in several o'l my prior applications. for example. in my application h'erial No. 38.132. filed July (3. 191:). This speed control apparatus. generally considered. comprises a speed-re sponsive device or governor. which represents or establishes the actual speed of the train: a permissive speed device. which when set into operation. establishes gradu ally decreasing permissive speeds: and suitable means and appliances responsive to the joint action of the speed governor and the permissive speed device. which actuate contacts or the like torcontrollino the brakes whenever the actual speed of. the train exceeds the permissive speed prescribed at that instant by the permissive speed device. In the simplified construction of parts illustrated. a governor G is connected to a shaft ll. which. is supportei'l in suitable fixed hearings l2. and which is connected in any suitable manner (not shown) to the car Wheels i speed position.

oraxle of the vehicle. The shaft 11 is rotated in accordance with the speed of the vehicle, and as this speed varies, the governor weights 13 are thrown outward by centrifugal force against the opposition of a spring 14 to raise a sliding sleeve or collar 15 to a position corresponding with the existing speed. Thus, the position of the collar 15 represents the actual speed of the vehicle.

The permissive speed device comprises a cam M fixed to a cam shaft 16, which is journaled in suitable bearings 17. and which is biased by a spring 18, or equivalent means, to a predetermined initial or maximum The cam shaft 16 has fixed thereto a worm gear 19, having a cutaway portion 20. Above the worm gear 19 is a worm 21 on a shaft 22, and the shaft 22 is driven through a universal coupling connection 23 and an auxiliary shaft from the shaft 11 by bevel gears 24 and 25. The worm 21 is normally held in the raised position out of mesh with the worm wheel 19 by a cam starter solenoid or magnet CS. The core 26 of this cam starter magnet CS is pivotally connected to a sleeve 27 loose on the shaft 22, so that the shaft 22 may be raised and lowered while rotating.

The means for detecting when the actual speed of' the train exceeds the permissive speed, is shown as comprising a floating lever 28, which is bifurcated at one end and carries rollers cooperating with flanges on the collar 15 of the governor G, so that this end of the floating lever 28 m'oves up and down in correspondence with the change in the actual speed of the train. The other end of the floating lever 28 is provided with a roller 29 resting upon the edge of the cam M. A contact operating member 30 is piv otally connected to the floating lever 28 at an intermediate point between its ends, and when this intermediate point of said lever has been raised to a predetermined extent, an insulated striking piece '31 engages the contact spring 32 and moves it out of contact with the fixed contact 33. A spring 34, connected to the operating member 30 and a suitable fixed member, serves to maintain the roller 29 in contact with the edge of the cam M.

The cam shaft 16 carries an arm 35 which is adapted to engage one or the other of two contact springs 36 (depending upon the direction of rotation of said cam shaft) after the cam has attained its minimum speed position. whereupon one of said contact springs 36 is moved into contact with a suitable fixed contact 37.

\Vhile various types of construction may be employed for causing an automatic application of the brakes, subject to the intervention of the engineer, I have illustrated a construction in which a pneumatic device F is set into operation whenever the actual speed of the train exceeds its permissive speed, said pneumatic device acting to operate the usual engineers brake valve to the service position, unless the engineer prex ents such operation by holding his brake valve handle against movement. The engineers brake valve E is illustrated conventionally. A gear-sector 38 is fastened to the usual stem or shaft of the engineersbrake valve E to which the engineers brake valve handle 39 is applied. A rack 40, supported by suit able fixed guides 41, meshes with the teeth of the sector 38, and this rack is integral with, or attached to, a piston rod 42, which passes loosely through a piston 48 in a cylinder 44. The end portion of the piston rod 42 isscrew-threaded and carries adjusting nuts 46. adapted to be engaged by the piston 43: and the movement of the piston 43 to the right, as viewed in Fig. 2, is limited by suitable fixed stops .45 attached to the inside of the cylinder 44. Pressure is supplied to the cylinder 44 on the lefthand side of the piston 43, through a pipe 47 from the main reservoir of the air brake system, or other sources of compressed air, whenever an electro-pneumatic valve E. P. V. is operated. As shown, this electro-pneumatic valve E. P. V. comprises two valves 48 and 49 carried by a stem 50, which is connected to the armature 51 of a solenoid or magnet 52. The magnet 52 is normally energized to seat valve 48 and open valve 49, so as to connect the cylinder- 44 and pipe 47 to atmosphere through an exhaust port 53.

The operation of this form of brake controlling apparatus will be evident with only a brief explanation. Upon the deenergization of the magnet 52, its stem is moved downward by gravity, assisted by main reservoir pressure acting against the valve 48. This closes valve 49 and opens valve 48, so as to supply main reservoir pressure through pipe 47 to the cylinder'44 against the lefthand face of the piston 43. This pressure moves the piston 43 to the right against the adjusting nuts 46, and unless the engineer holds his brake valve handle 39, his brake valve E is operated to the service position. The stops 45 and the adjusting nuts 46 enable the engineers brake valve E to be automatically operated accurately to the service position by the-pneumatic device F. \Vhen the magnet 52 is re-energized, the valve 48 is closed and the valve 49 is opened, thereby cutting off the supply of pressure to the cylinder 44 and exhausting the air already in said cylinder to atmosphere through the exhaust port 58. It will be noted that the pneumatic device F does not interfere with the operation of the brake valve E by the engineer in the usual manner, since the pis ton rod 42 passes loosely through the piston 43, and permits movement of the brake valve handle 39 to any position desired. Obviousiii ly, other arrangements and constructions of parts other than that shown may be em ployed to cause an automatic application of the brakes unless the engineer takes appropriate action to prevent or oppose such brake application.

The impulse receiving element L on the vehicle, which cooperates with the trackway element T, comprises an inverted U-shaped yoke or core 54 having pole pieces 55. This yoke 54 is carried by the vehicle so that its pole pieces 55 pass directly over thepole pieces 7 of the trackway element T. The air gap between the pole pieces 7 and 55 ot' the trackway and ear-carried elements is preterably made as short as practical railroad clearances will permit, although satisfactory operation may be obtained with air gaps of three or four inches. On the legs of the yoke 54 are coils 56 and 57. The coil 56, conveniently termed the magnetizing coil, is included in a normally closed circuit which also includes a battery 58 and the coils of a check relay 59.

This check relay 59 is preferably of a balanced type so as to detect either an abnormal increase or decrease in the current flowing in the circuit for the magnetizing coil 56. As illustrated, the armature 60 of the check relay 59 is biased by a spring 61, preferably 'ad uStable, so as to be in a neutral or balanced position when the normal value of current flows through said relay. This armature 60 carries an insulated striking piece 62 positioned between two contact springs 63-63 which normally contact with the fixed contact points 64. The circuit controlled by the relay 59 is carried through the contact springs 6363 and the fixed contacts 64. When normal current for which the relay is adjusted flows through its coils, the attraction of the armature 69 just balances the tension of the spring 61. It the current decreases below this normal value, due to an interruption of the circuit or a depreciation of the battery, the spring 61 over-balances the attraction of the armature 60 and moves the contact spring 63 out of contact with its fixed contact 64, thereby interrupting the circuit. If, however, the normal value of current through the relay 59 is increased, due to a cross or the like, the attraction of the armature 60 over-balances the spring 61, and opens the circuit at the other contact spring 63. In this way, the check relay 59 checks the energizing circuit for the magnetizing coil 56 against failures due to breaks, crosses, and the like.

The other coil 57 of the car-carried element L, conveniently termed the receiving coil, is connected in a similar normally closed circuit which includes a battery 65 and the coils of a control relay K, said control relay R being preferably constructed in the same way as the check relay 59. The

battery 65 is intended to supply only sutfieient current to enable the adequate checking of the'circuit for the receiving coil 57, and for this purpose may be much smaller than the battery 58 which is required to supply suthcient current to magnetize the yoke 54.

The impulse transmitting means operates in the following manner. Under clear traffic conditions. the line relay 9 is picked up and short-circuits the coils 8 of the traekway element T, and when the yoke-54 of the car-carried element L passes over this trackway element in its proceed controlling condition, the reluctance of the magnetic circuit through the coils 56 and 57 is not radically changed. since the short-circuited coils 8 of the trackway element T oppose the passage of flux through the yoke 6. Under dangerous traitic. conditions, however, the coils 8 of the trackway element T are open-circuited, so that this trackway element presents in effect a magnetic bridge or loop for the yoke 54. so that as the train passes. the reluctance of the magnetic circuit through the coils 56 and 57 is greatly changed. This change in flux induces a current in the receiving coil 57 which in turn varies the current flowing through the control relay R in such a manner that its Contacts are opened. Thus, the control relay R is operated to open its contacts at each caution signal, but is not operated at a clear signal. By employing an appropriate arrangement of trackway controlling circuits for governing the coils 8 of the traekway element T, in a manner which will be readily apparent to those skilled in the art, the system may be arranged to cause operation of the control relay R at a stop or danger signal, as well as at a caution signal, suitable provision being made, of course. to prevent a train stopping itself upon entering a block.

Regarding the operation of the speed control apparatus on the locomotive. 'or other railway vehicles, when the control relay R is operated at a caution signal, the opening of its contacts interrupts a stick circuit for a quick-acting relay Q carried through its contact finger 66; and the dropping ot the contact finger 67 of this relay Q opens a circuit for normally energizing the cam starter magnet CS, these circuits being readily traced on the drawing. The worm 21 now drops into mesh with the worm gear 19. and this establishes an operating connection between the cam shaft 16 and the car wheels, so that as the train progresses, the cam shaft 16 and the cam M are gradually turned from their normal or initial position, in one direction or the other depending on which way the vehicle is headed. As the cam M is turned, it raises the roller 29 at one end of the floating lever speed of the vehicle is less than the permissive speed prescribed by the existing position of the cam M, the contact operating member is raised far enough to separate the contacts 32 and 33 and deenergize the magnet 52 of the E. P. V., thus'tending to apply the brakes in the manner previously explained.

.The shape of the cam M is selected with due regard to the travel of the collar 15 of the governor G and the proportion of theother parts of the apparatus, such that the train must observe a limiting speed at all points of its travel through the caution block, corresponding with the curves of permissive speed, like the curves X indicated in Fig. 1. These curves of permissive speed are basedupon the braking performance of the train in question, and, generally stated, represent the various speeds for the different points in the block at which the train may safely travel and yet be brought to a stop by a service application of its brakes before reaching the end of the block. It will be noted that these curves X of permissive speed, as shown ,'change from a maximum speed of 60 miles an hour down to a minimum speed of 10 miles an hour. This maximum speed of 60 miles per hour is' merely representative of the normal running speed assumed for the train in question, and the minimum speed of 10 miles per hour is one which has been arbitrarily as sumed to be sufliciently low for ordinary safety. The maximum and minimum speeds, and the permissive speed curves shown are merely illustrative, and are subject to considerable variation in practice. In the type of permissive speed device shown in Fig. 2, the minimum radius of the cam M corresponds with the maximum or normal running speed of the train to which the cam is applied; and during the gradual turning movement of this cam in proportion to the distance traveled by this train, the radii of the cam which pass successively under the roller 29, are made longer in accordance with the decrease in permissive speeds indicated by the permissive speed curves X. After the train has traveled a certain distance, (which is based upon its braking performance), the run down of the cam is completed, and its maximum radius, corresponding to the minimum permissive speed, is brought under the roller 29. From this point the rest of the cam surface is made concentric with its shaft 16, so that further movement of the cam merely holds the roller 29 stationary. The shape of the cam shown in Fig. 2 has been determined upon the basis of certain arbitrarily assumed factors, and while it represents in a general way the shape of a cam suitable for practical use, it should be understood that the shape illustrated is merely illustrative and would be varied in actual practice to suit the braking performance of different trains on different railroads. In this connection, it will be observed that the particular cam M illus-- trated is symmetrical, so that it acts to pro duce the same movement of the roller 29 when turned in either direction from its initial or maximum speed position. This arrangement is employed to take care of the different directions of rotation of the 'cam shaft 16 depending upon Which way the car or locomotive is headed or traveling along the track; but this use of a symmetrical cam for this purpose is not compulsory and other expedients for accomplishing the same end may be employed.

Considering now the significance of the permissive speed curves X shown in Fig. 1, if a train should enter the block B when the block C is occupied and should be traveling at its normal speed of 60 miles an hour, it is evident that the brakes should be immediately applied in order to slow the train down to a safe s eed before it reaches the end of the block If, however, the train in question should enter the block 13 at a moderate speed of 30 miles per hour, for example, it could safely travel at this speed for a considerable distance into the block B before it would be necessary to, apply the brakes. All" of this is taken care of by the speed control apparatus previously pre scribed, since the automatic application of the brakes does not occur until the train exceeds a permissive speed prescribed for its particular location in the block. In other words, all of the space below the permissive speed curve X is free space, so to speak, and the engineer may run his train at any speed he desired at any point in the block, provided he does not at any time exceed the permissive speeds indicated by this curve X. Thus, the train is always governed safely, in spite of the various speeds at which it may enter a block or travel through difconditions found on the steepest down grade;

or, if found desirable, any one of the various expedientsdisclosed in my prior application may be .employed to provide different permissive speed curves for blocks having different braking characteristics. Since the system constructed in accordance with the present invention is more of a guidance and assistance to the engineer than an absolute automatic control, I prefer in most instances to employ a simple system using only one cam providing for one permissive speed. curve which is best suited to average braking onditions. and the engineer being depended upon to avoid premature brake applications, or to safeguard his train by earlier brake applications in whatever manner the special'trackway conditions at different locations may require.

After a train, which has been subjected to the speed control previously described, reaches the end of the block, the cam shaft- 16 will have been moved to the point where the arm 35 closes one or the other of the pairs of contacts 3637, thereby picking up the relay Q and reenergizing the cam starter magnet CS. This raises the worm 21 out of mesh with worm gear 19 and permits the spring 18 to restore the cam shaft 16' and the cam M back to their normal or initial position. This immediately removes the speed restriction upon the train, as indicated by the vertical line at the end of each block in Fig. 1. If the'next block which the train is about to enter isstill occupied at the time the train reaches its entrance, the block signal guarding the entrance to this block would be at stop, and it is contemplated that the engineer will control his train in the appropriate manner on the side of safety in accordance with the usual rules, even though the speed restriction imposed by the cam M has been automatically removed. This automatic restoration of the cam M to its initial position after it has run down to its minimum speed position. without regard to traffic conditions, avoids the complication of providing special devices and circuit arrangements to give an automatic reset for the cam from the track. If, for any reason, due to a failure of the parts or circuits controlling the automatic resetting of the cam, said cam should fail to be restored to its initial position after having run down to its minimum speed iosition the worm 2-1 will drive the worm w eel 19 to the point where said worm merely rotates idly in the cutaway portion 20 of said worm wheel Thus, the cam will be held in its minimum speed position, rather than continued in motion and eventually brought back to its maximum speed position. since the latter would be improper and perhaps unsafe. In case of such defect, the engineer would, of course. have to run his train as best he could without the aid of the automatic speed control apparatus, until repairs or adjustment could be made. YVhile thus running without the protection of the automatic train control system, the engineer could prevent abnormal brake application by keeping hold of his brake valve handle, or he might operate some suitable form of cutout device. In any event, the failure of the cam to reset, would result in controlling the train on the safe side.

In case a block on the railroad, (represented for example by the block C), is longer than braking distance for a train running at normal speed, the train should be able to proceedsome distance into this block before the cam is set into operation. This is accomplished by locating the trackway element T for such a long block at an intermediate point in its length, such that this trackway element is at a distance from the exit end of the block corresponding with the run-out distance of the cam. This same principle may be applied to the various length of blocks on a railroad; and it is evident that the trackway elements may be located in each instance at the appropriate point in the block so as to start the cam into operation at the proper time to govern the tram safely and yet not unnecessarily delay the train. Thus, my system may be applied to situations Where there is considerable variation in the length of blocks, itbeing merely necessary to position the trackway elements at the proper point in each block. Ordinarily, the variou length blocks are at least as long as braking distance for the maximum normal running speed of trains, but if a block or blocks at certain localities should, for any reason, be shorter than this braking distance, the trackway element T could belocated in the rear of the entrance to the block, at braking distance from its exit end, so that the cam will be started soon enough to impose speed restrictions consistent with safety.

One important characteristic of my in vention resides in the fact that the control of the train is not taken entirely away from the engineer. so that he is able to hold off an automatic application of the brakes whenever, due to peculiar and special conditions, such brake application is not required for safety. Also, it may happen, after a train has passed a caution signal and proceeded part way into a. block, the next block in advance will clear up. If this should occur, with the system embodying my invention. the engineer could resume speed, if he desired, even though the cam continues to impose decreasing permissive speeds, this being accomplished by holding the brake valve lever 39. In view of the many variable factors entering into the braking of trains under various track and traffic conditions. it is sometimes difficult, without using complicated and expensive apparatus. to reproduce automatically the proper speed regulation best suited for safety and facility. This difficulty is obviated to a. large extent in my system by reason of the fact that the engineer may exercise his judgment and skill, whenever special conditions arise, so as to overcome the inaccuracies or deficiencies of the automatic mechanism. An automatic application of the brakes by the action of the train control apparatus, however, being given with due regard to the essential factors of the speed and location of the train, is one which the engineer will ordinarily find accurate, and one which he will be inclined to observe.

The system shown and described is susceptible of considerable modification, addil5 tions, variations and adaptations; and I de sire to have it understood that the specific embodiment of my invention herein dis closed is merely illustrative and does not exhaust the various constructions embody- 2O ing the same ideas of means underlying my invention.

What I claim as new and desire to secure by Letters Patent oft-he United States, .1s:-

1. In a system for automatically control ling the speed of trains on railroad tracks divided into blocks each provided with a track circuit, speed control apparatus on a railway vehicle including a permissive speed device adapted when set into operation to change gradually during the progress of the vehicle and impose decreasing permissive' speeds therefor, mean partly on the vehicle and partly along the track and governed by said track circuits for setting said permissive speed device into operation in each block when the next block in advance is occupied, and means on the vehicle for automatically restoring said permissive speed de- 40 vice to its initial maximum speed coiidi tioii after it has attained its ultimate minimum speed condition.

2. In a system for automatically control: ling the speed of trains on railroad tracks divided into blocks each provided with a track circuit, speed control apparatus on .a. railway vehicle including a permissive speed device which is adapted when set into operation to change gradually during the progress of the vehicle and impose decreasing permissive speeds therefor, means partly on the vehicle and partly along the track and governed by said track circuits for setting said permissive speed device into operation in each block when the next block in advance is occupied. a brake-setting appliance including an engineers brake valve adapted to be held against movement by the engineer to prevent its operation. and means for operating said brake-setting appliance when the actual speed of the ehicle exceeds its permissive speed.

3. Speed controlling apparatus For railway vehicles, comprising, a changeable permissive speed means adapted when set into operation to change gradually from an initial maximum speed condition to an ultimate minimum speed condition, and means sive speed device, means adapted to establish an operative connection between said permissive speed device and the wheels of the vehicle, aiidmeans dependent upon the movement of said permissive speed device tor automatically governing said means to discontinue such operative connection as soon as the permissive speed device has at tained its minimum speed position.

5. In an automatic train control system for railways having tracks'divided into blocks each provided with a track circuit, an impulse transmitting element associated with each block and located approximately at braking distance from the exit end of that block. means for governing the controlling condition of each trackway element in accordance with trafiic conditions in the next block in advance. automatic speed control apparatus on a railway vehicle. means for governing said apparatus including an impulse receiving device, said impulse transmitting element and receiving device cooperating inductively through an intervening airgap. and a brake-setting appliance actuated by said speed control apparatus, said appliance being adapted to be controlled by the engineer to prevent its operation.

(3. A vehicle equipment for automatic train control systems comprising, in combination with an cngineers brake valve. an appliance adapted when operated to exert a pressure tending to move the engineers brake valveto a brake applying position and thereby cause an automatic brake application, said movement of said b'ake valve being preventable by the engineer, and auto. matic speed control apparatus on the vehicle including a speed responsive device driven from the wheels thereof for governing said appliance.

7. A vehicle equipment for automatic train control systems comprising a movable device adapted when moved to an active position to apply the brakes on the vehicle, said device beingin a position and adapted to be manually held against movement by the. engineer. and automatic speed control apparatus including speed responsive means governed in. accordance with the actual speed of the vehicle for initiating the 1novcment of said device whenever the vehicle excceds-prescribed limiting speeds at predetermined points along the track.

8. In a speed control apparatus for railway vehicles which are provided with air brake equipment including an cngineers brake valve. a speed responsive device governed in accordance with the actual speed of the vehicle, and means governed by said device for exerting a pressure tending to operate the engineers br ikc valve to a brake applying position, the pressure exerted by said means being such that the engineer may overcome it.

9. In a system tor automatically controlling the speed of railway vehicles on tracks divided into blocks each provided with a normally closed track circuit. an impulse transmitting element associated with each block and located approximately at service braking distance from the exit end of that block, means for governing the controlling condition of each trackway element in accordance with traiiic conditions in the next block in advance, automatic speed control apparatus on the railway vehicle including a permissive speed device. and adapted to control the brakes of the vehicle, means for initiating the operation of said permissive speed device at each trackway element imposing caution control, automatic means on the vehicle for restoring said device to its initial condition, and means whereby the engineer may prevent an application of the brakes by the action or said speed control apparatus.

10. Speed control apparatus for railway vehicles comprising, a permissive speed dedevice and governed by the permissive speed 7 device, and means dependent upon the change of said permissive speed device to its ultimate condition for governing its op eration.

11. Speed control apparatus for railway vehicles comprising a biased movable permissive speed element, electrically controllable means adapted to connect said element with the wheels or the vehicle, a stick relay controlling said means. and means torestablishing the pickup circuit for said relay when said element has attained a predetermined position.

12. Speed control apparatus for railway vehicles comprising a permissive speed device adapted when set into operation to change from an initial ioiidition to an ultimate condition and impose decreasing permissive speeds, a speed responsivedevice driven from the wheels of the vehicle, brake controlling means governed jointly by said devices. and means on the vehicle for automatically restoring the permissive speed dc.- vice to its initial condition after a predetermined distance of travel of a vehicle.

13. In an automatic train control system, speed control apparatus in a vehicle adapted when set into operation to enforce predetermined speed limits, automatic means on the vehicle for restoring said apparatus to its initial condition after a predetermined distance of travel of the vehicle, and means comprising traiiic controlled track elements cooperating inductively through an inter vening airgap with a receiving element on th vehicle for setting said apparatus into operation.

14. In an automatic train control system, speed control apparatus on a vehicle comprising a biased permissive speed device adapted when set into operation to change from an initial condition to an ultimate condition during the progress of the vehicle and impose during such change decreasing permissive speeds, automatic means wholly on the vehicle for restoring said device to its initial condition, and traitic controlled means for setting said permissive speed device into operation.

15. In an automatic train control system for railroads having blocks of different length, speed governed brake control appara'tus on a vehiclecomprising a permissive speed device adapted when set into operation to change to an ultimate condition after a predetermined distance of travel of the vehicle, trafiic controlled means for setting said device into operation in each of said blocks at a predetermined distance from the exit end of that block, and automatic means forrestoringsaid permissive speed device to its initial condition at the end of each block.

16. In an automatic train control system for railroads having blocks of different length, automatic speed control apparatus on the vehicle adapted when set into operation to regulate the speed thereof in accordance with its location, traliic controlled means for setting said apparatus into opera tion in each block at braking distance from the exit end thereof, said means comprising elements on the vehicle and th track cooper ating inductively and transmitting controla ling impulses through an intervening airgap, and automatic means on the vehicle for restoring said apparatus to its initial condition at the end of each block.

17. In a train control system for railroads divided into blocks, the combination with a block signal system for said railroad including trackvvay' signals governed automatically in accordance with traiiic conditions, brake control means on a vehicle including a speed responsive device, the effective operation of said means to cause a brake application being manually preventable by the engineer, and means partly on the vehicle and partly on the track for governing the brake control means in accordance with traffie conditions.

18. In a train control system for railroads divided into blocks, the combination with a block signal system for said railroad includmg trackway signals governed automatically in accordance with traffic conditions, automatic brake control apparatus on a vehicle comprising a movable permissive speed device adapted in its different positions to establish a plurality of speed limits which the vehicle can not exceed without tending to apply the brakes and an actual speed device driven from the wheels of the vehicle, said brake control apparatus including means manually operable by the engineer for preventing a brake application by the action of said apparatus, and means for overning the operation of said apparatus rom the trackway in accordance with trafiic conditions.

19. In a train control system for railroads divided into blocks, the combination with a block signal system for said railroad including trackway signals governed automatically in accordance with trafiic conditions, brake control apparatus on a vehicle including changeable permissive speed means and a speed responsive device, means under the control of the engineer for preventing a brake application by the action of said apparatus, and influence communicating means partly on the vehicle and partly on the track and acting through an intervening air gap for governing the operation of said apparatus in accordance with trafiic conditions.

20. In a train control system for railroads divided into blocks, the combination with a block signal system for said railroad includ ing trackway signals governed automatically in accordance with trafiic conditions, an engineers brake valve, a device operable to move the brake valve to a brake applying position, such movement being preventable by th engineer, speed responsive means for controlling the operation of said device, and automatic means for governing the speed re sponsive means from the trackway.

21. In a train control system for railroads divided into blocks, the combination with 'a' block signal system for said railroad including trackway signals governed automatically in accordance with trafiic conditions, an engineers brake valve, a device operable to move the brake valve to a brake applying position unless such movement is prevented by the engineer, electrically controlled apparatus including a speed responsive means for governing the operation of said device, and electro-responsive means influenced from the trackway in accordance with trailic conditions for controlling said apparatus.

22. In a train control system for railroads divided into blocks, the combination with a block signal system for said railroad includin trackway signals governed automatica ly in accordance with traflic conditions, a brake control valve, speed governed apparatus tending to cause operation of the valve when predetermined speed limits are exceeded, means manually operable by the engineer for preventing operation of said valve, and control means for said apparatus governed in accordance with trafiic conditions and acting by the transfer of magnetic flux between the trackway and the vehicle.

23. In a train control system, the combination with an engineers brake valve, a device for applying pressure tending to move said valve to a brake applying position, apparatus for governing said device including permissive speed means and a speed responsive means driven from the wheels of the vehicle, said apparatus actuating said device if the actual speed exceeds the-permissive speed, and means partly on the vehicle and I partly on. the track and acting through an intervening air gap for controlling said apparatus in accordance with traflic conditions.

24:. In a train control system, a brake control appliance on a vehicle including a movable member adapted to have its movement prevented by the engineer and thereby prevent effective operation of said appliance, and speed governed apparatus controlled from the trackway through an intervening air gap for controlling said appliance.

25. A train control system for railroads comprising, in combination with the fixed signals of a block signal system, a brake control appliance including a movable element operable manually by the engineer to prevent a brake application, apparatus including a speed responsive means for controlling said appliance, and means for automatically governing said apparatus from, the-trackway at each caution signal.

26. A train control system comprising, speed governed brake control apparatus on a vehicle changeable to an ultimate minimum speed condition and adapted to continue in operation until restored, means manually operable by the engineer for preventing a brake application by said apparatus, traflic controlled means for initiating the operation of said apparatus, and automatic means on the vehicle for restoring said apparatus after it has attained its ultimate condition.

27. Train control apparatus for railway vehicles comprising, an enginee'rs brake valve, a device operable to move said valve to a brake applying position unless the engineer prevents such movement. mechanism for governing said device including aspeed responsive means and a permissive speed means changeable to an ultimate condition, said mechanism when set into operation continuing in operation until restored, and automatic'means wholly on the vehicle for restoring the permissive speed means after it has attained its ultimate condition.

28. A system for regulating train movement on railroads comprising, in combination with a block signal system having trackway signals, brake control apparatus on a vehicle changeable to an ultimate condition and adapted to continue in operation until restored, means manually operable by the engineer for preventing the eflective operation of said apparatus, meanspartly on the vehicle and partly on the track for initiating the operation of said apparatus at each caution signal, and automatic means on the vehicle for restoring the apparatus independently of trackway control after a predetermined distance of travel of the vehicle.

29. A system for regulating train movement on railroads comprising, in combinatioii-with a block signal system having trackway signals, brake control apparatus including an engineers brake valve and means acting when conditioned for operation from the trackway to move said valve to a brake applying position when the vehicle exceeds predetermined speed limits, said apparatus when set into operation continuing in operation until restored, means partly on the vehicle and partly on the track for initiating the operation oi said apparatus in each caution block, and means on the vehicle for restoring said apparatus independently of trackway control.

30. In a train control system. Llib COIAlJl nation with speedgoverned brake control apparatus on a vehicle adapted when set into operation to continue in operation unt restored, said apparatus assuming an ultimate minimum speed condition, means man ually controllable by the engineer for preventing efi'ective operation of said apparatus, means partly on the vehicle and partly on the track and acting through an intervening air gap to initiate the operation of said apparatus under dangerous trafiic conditions, and automatic means on the vehicle for restoring said apparatus after it has attained its ultimate condition.

31. In a train control system, the combination with brake control apparatus on a vehicle including a speed responsive device and operable to an ultimate condition in which the vehicle may proceed below a predetermined minimum speed, said apparatus continuing in operation until restored, means for initiating the operation'of said apparatus from the trackway under dangerous trailic conditions, and means on the vehicle for automatically restoring said apparatus after it has been operating for a certain distance of travel of the vehicle.

32. Train control apparatus for railway vehicles comprising, in combination with brake control apparatus operable to establish a minimum speed limit for the vehicle said apparatus continuing in operation and iaeaeis maintaining such minimum speed limit until restored, and automatic means on the vehicle for restoring said apparatus.

33. In a train control system for railroads, the combination with an engineers brake valve. apneumatic device operable to move the brake valve to a brake applying )OSltlUIl unless such movement is prevented by the engineer, means for controlling said device including speed responsive means and changeable permissive speed means, said permissive speed means assuming an ultimate minimum speed condition and continuing in that condition until restoredpmeans partly On the vehicle and partly on the track and acting through an intervening air gap for initiating a change of said permissive speed means under dangerous trafiic conditions, and an automatic means on the vehicle for restoring the permissive speed means after it has attained its ultimate condition.

34. In a system for controlling the speed of railway vehicles in accordance with trafiic conditions while traveling through blocks of different length, car apparatus comprising changeable permissive speed means operable to establish variable speed limits said permissive speed means having an ultimate minimum speed condition and when changed to that condition continuing to establish a minimum speed limit until restored, and automatic means effective as soon as the permissive speed means attains its ultimate condition to cause restoration thereof.

In a train control system, the combination with an automatic block signal system including trackwa-y signals, car-carried brake control apparatus including permissive speed means and an actual speed device, said permissive speed means when operated continuing in operation until restored, means controlled from the trackway for initiating the operation of the permissive speed means in each block when the next block in advance is occupied, and automatic means on the car for restoring the permissive speed means independently of trat'iic conditions.

36. In a train control system, the combination with brake control means partly on .a vehicle and partly on the track acting while the car is traveling in a block next in the rear of an occupied block to cause a brake application unless the car assumes successively lower speed limits as it approaches the occupied block, of automatic means for restoring said means independently of trafiic conditions when the vehicle reaches approximately the 'end of the block.

37. Speed governed brakeco-ntrol apparatus for railway vehicles comprising, a permissive speed cam, electrically operable means adapted when deenergized to operatively connect said cam to the wheels of the vehicle, and means for automatically energizing said means when the cam has been turned to a'predetermined position.

38. Train control apparatus for railway vehicles adapted to apply the brakes thereof dependent on speed comprising, a movable permissive speed device having an initial position and an ultimate position, electrically operable means controlled from the trackway for governing the movement of said device, and automatic means for independently causing restoration of said device to its initial position after it has attained its ultimate position.

39. Train control apparatus for railway vehicles comprising, a changeable permissive speed means having a biased initial condi tion and an ultimate condition, a stick relay controlled from the trackway for governing the change of said means, a pick-up circuit for said relay, and automatic means for closing said circuit when the permissive speed means has been changed to its ulti mate condition.

40. Train control apparatus for railway vehicles comprising. in combination with an engineers brake valve, a pneumatic device operable to apply pressure to said valve to move it to a brake applying position, the pressure exerted by said device being small enough to allow the engineer to forcibly prevent such movement of said valve, an electrically operable valve controlling said device, and speed governed means adapted to determine speed limits for the vehicle and acting to tend to actuate said valve when the existing speed limit is exceeded.

ii. In a train control system, brake pontrol apparatus on a vehicle including a speed responsive .device and acting to cause an automatic brake application" subject to prevention by the engineer when the Vehicle exceeds predetermined speed limits, and control means for said apparatus comprising a track element constituting an inert magnetic body when in the active stopping condition, and a car element adapted to beinfiuenced by the magnetic properties of the track element.

42. In a train control system, the combination with brake control apparatus on a vehicle for causing an automatic brake application when the vehicle exceeds predetermincd speed limits, means for controlling said apparatus comprising a track element constituting an inert non-magnetized partial magnetic circuit when in the active stopping condition, and a cooperating car element including amagnetized partial magnetic circuit and a coil magnetically associated therewith, said track element changing the reluctance of the magnetic circuit of said car element, thereby producing a change in flux and inducing a voltage in said coil.

WINTHR-OP K. HOWE,

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