US1717339A - Train control - Google Patents

Description

6 Sheets-Sheet H mm- W. K. HOWE TRAIN CONTROL.

Filed Aug. 25, 1924 June 11, 1929.

fl\\\ \L RNEY Julie 11, 1929. w, HOWE 1.717.339

, TRAIN CONTROL Filed Aug. 25, 1924 6 Sheets-Sheet 2 June 11, 1929 w. K. HOWE 1.717.339

TRAIN CONTROL Filed Aug. 25, 1924 6 Sheets-Sheet 3 IN V TOR.

m9 BY FIG. 6.

June 11, 1929.

Filed Aug. 25, 1924 W. K. HOWE TRAIN cou'rRo 6 Sheets$heet INV TOR.

A TT RNEY Patented June 11, 1929.

UNITED/STATES 1 1,717,339 PATENT oF Ics.

WINTHROP K. HOWE, OF ROCHESTER, NEW YORK, 'ASSIGNOR, TOGENERAL SIGNAL COMPANY, OF ROCHESTER, NEW YORK.

TRAIN CONTROL.

Application filed August 25, 1924 Serial No. 733,975,

This invention relates to automatic train control systems, and more particularly to continuousinductive control systems of the so-called three-speed of three-position type.

Briefly stated, a system of this kind includes a three-position or polyphase alternating current relay on a railway vehicle which has one of its field windings or phases energized in response to current 'fiowing down one rail and back through the other ahead of the train, and has its other field winding or phase energized in response to current flowing in the two rails in multiple under the train, these currents being detected by suitable influence receiving means in front of the first axle and at a point some distance in the rear of the first axle, respectively, and being amplified by suitable vacuum tube amplifiers and associateddevices. By reason of the factthat the relay is normally energized in response to trackway current, it is difficult to keep this relay from droppingwhen certain sections are passed where it is difiicult to provide such current in the track rails. These sections are conveniently called dead-sectionsv, and are found at frogs, cross-overs, staggered joints between blocks, and the like. v

In the provision of automatic train control apparatus, it is desirable to maintain the protection that is afforded without suchapparatus, namely, that due to the vigilance of the engineer; and in order to maintain such vigilance and keep the engineer from wholly relying on the automatic apparatus, it is proposed in accordance with the present invention to require him to perform a certain act in passing or approaching a caution, or. a danger signal, to show, that he has observed the signal and knows that he is entering more dangerous territory. Such an acknowledging act is conveniently enforced by requiring theengineer to operate some thing, such as a push button, at or just before the time when the relay changes either from a clear or a caution to a more dangerous position.

Since, as heretofore,mentioned, dead-sections are bound to be encountered, it is proposed" in accordance with the present invention to require the engineer to manifest his viligance onlywvhen the relay changes to an adverse position and stays there for a certaindistance of movement of the. train. It is considered that such acknowledging act manifests that the engineeris alive and alert,

danger ed SPGQClllll'lltS. Further, in order to give the engineer adequate'information as to what'he is required to do in order to avoid an automatic brake'application and an associated penalty it is proposed in accordance with the presentinvention 'to providea suitable warning signal, which will keep him sufficiently informed to enable him to control the train without the infliction of such a penalty. The particular type of audible warningrsignal proposed in connection with the present invention is one telling the-engineer when he has sufliciently decreased his speed, rather than telling him when his speed is excessive.

Since automatic train control systems of the continuous inductive type are of a character that restrict the speed uponabsence of trackway current, it is essential to provide suitable'means for maintaining the car-carried train control mechanism in an inactive or non-controlling condition when the train enters territory which is not equipped for automatic train'control. purposes; and in accordance with the present invention, it is proposed to provide a stick relay which, when in, its energized position, advises the engineer by a suitable cab signal that he is moving in non-control territory and which makes a portion or all of the train control mechanisminoperative, this relay preferably being automatically picked up in response to a change from the normally energized position of the relay to a ole-energizedposition thereof, providing the engineer makes a cer tain acknowledging act at the timeto show that he is aware of entering such non-control territory.

Other objects, purposes, advantages and characteristic features of the invention will in part be pointed out hereinafter and in part be obvious from the accompanying drawings.

In describing the invention in detail reference will be made to the accompanying drawings in which Fig. 1 shows a portion of trackway equipped for train control purposes, together with a conventional illustration of a railway vehicle equipped with a main car relay and suitable 'current detecting and amplifying devices, the shaded areas shown in this figure representing the various speeds through various sections of a caution block at which an audible warning signal is sounded;

Fig. 2 shows mechanism for closing contacts at different speeds, at different distances from a certain point at which the main car relay has changed, and if the actual speed as compared with a permissive speed is excessive;

Fig. 3 conventionally illustrates the co-car ried apparatus together with the circuit arrangement connecting the various elements carried on the car;

Fig. 4: shows the various speeds above which the audible warning signal is sounded through certain sections in a caution block by the car-carried apparatus shown in Fig. 3, with the warning signal control modified as shown in Fig. 4A;

Fig. 4A shows a modified form of control of the warning signal;

Fig. 5 illustrates the various speeds be tween which, as well as the sections through which, the warning signal is sounded when employing the modified form of 1 control shown in Fig. 5A;

Fig. 5A shows a further modified form of control for the warning signal; and

Fig. 6 shows a modified type of trackway system, whereby the trainhas its maximum permissive speed gradually reduced in the first clear block in the rear of a caution block.

Referring to Fig. 1 ofthe drawings, a track has been illustrated by rails 1 divided into blocks in the usual way by insulated joints 2, the block I and the adjacent ends of two other blocks H and J being shown. Since the various parts and. circuits associated with the blocks are the same, like parts of each block are designated by like reference characters having distinctive exponents.

At the exit end of each block is impressed across the rails the usual source of trackway energy,which in the arrangement shown is supplied by a transformer 3 connected across the track through an impedance la A suitable track relay 5, responsive to alternating current, is connected across the rails at the entrance end of such blocks. Although the train control system embodying the present invention may be used either with or without wayside signals, wayside signals are preferably employed to aid the engineer inacknowledging, and although either'light signals or semaphore signals may is deenergized.

be used for convenience semaphoresignals Z only have been shown conventionally, without illustrating their well known con trol circuits and devices.

In addition to the usual alternating current normally closed track circuit, which receives its energy from the transformer 3, circuits are provided for causing a flow of current through the two rails in multiple. This current is displaced in phase with respect to the track circuit current, and is at times out off in accordance with traffic conditions ahead; and for conducting this current to the rails the balancing resistances 6, 7 and 8 have been illustrated, which are located at the entrance end, at an intermediate point B, and at the exit end of the block, respectively. The first section of the block, extending from the balancing resistance 6 to the balancing resistance 7, has current applied thereto in one direction or the other, depending on whether the track relay in the next block in advance is energized or de-energised, through circuits including front contacts 10 and 11 which circuits are readily traced in the drawings; and the second section of the block extending from balancing resistance 7 to balancing resistance 8 has its line phase energized only when the contact 12 of the track relay .5 is in'its raised position.

For convenience, the usual track circuit will be referred to as the track phase or loop circuit hereinafter, and the circuit including the two rails in multiple will be referred to as the line phase or simplex circuit.

On the railway vehicle, conventionally illustrated by the wheels and axles 15, is provided a main car or control relay MB of the polyphase induction type. This relay is preferably constructed like those commonly used in railway signalling; and gen erally speaking, it has two field windings and a movable ele1nent, such as a rotor or a vane, together with suitable contact fingers operated by said movable element. The relay MB is biased by suitable springs or counter-weights so that its movable element assumes an intermediate or neutral position if either one or both of its field windings The contacts operated by the movable element MR'have been shown conventionally as single contact fingers, capable of assuming any one of three dilii'erent positions and arranged to cooperate with stationary contacts indicated as arrows.

Directly ahead of the first axle of the train is carried a pair of influence receiving elements or coils 16, which are connected to the track phase amplifying device TA in a manner so that voltages induced in these coils, due to currents flowing in opposite,

directions in the rails, are cumulative. The

tying device TA are connected to one :field winding 17 of the main relay MR, so that a current is caused to flow inthe coil 17 of this relay in response'to current flow in the track phase, that is, in one direction in one rail and in the other direction in the other rail ahead of the train. Similarly, another pair of influence receiving coils or elements 18 is provided several axles in the rear of the first axle, and preferably in the rear of the tender; and these coils are connected in series to the line phase amplifying device LA in a manner so that the voltages induced in these coils, due to currents flowing in the same direction in the track rails, are cumulative, the output leads of this amplifying device LA being connected to the other coil 19 of the main relay MR. In the arrange 'ment shown these coils 16 and 18 surround cores of laminated iron, which are adapted to act as flux collectors, but these cores may be omitted if desired, from certain systems depending on the frequency and value of the trackway currents used.

If the trackway currents flowing in the track and line phase respectively are displaced in phase the relay MB is energized to shift its movable element in one direction and if one of these phases is reversed, the relay is'energized to shift its movable element in the other direction; and if either of these phases has its current interrupted, the movable element of the relay assumes its deenergized position. It is thus noted that a train moving in a clear block will have this relay energized in the normal position, and as the train enters a caution block, the relay will assume its reve *sed position between the entrance to the block and the point B, and will assume its de-energized position from the point B to the end of the block, all by reason of the control effective on the line phase circuit. Also, as the train moves in an occupied block, this relay assumes its deenergized position, because there is no track phase current present in such occupied block, since this currentis shunted from the train in question by-another train ahead.

As shown in Fig. 1 and as heretofore mentioned, the blocks are divided into two sections as far as their control is concerned under caution traffic conditions of a block; that is, at the entrance to a caution block the main relay changes from its normal onergized position to its reversedposition, and at the point B in the block it changes the second section, respectively, of a caution block, similar to-the arrangement shown in the application filed July 26, 1923-by Howe and Bushnell, No. 653,898, to which reference may be had, so that a brief description ofuthe car-carried apparatus will sutlice herein.

Referring now to. Fig. 2, there has been shown an arrangement of mechanisms whereby circuits may be made and broken at different speeds, after the train has moved a certain distance into the first or second section of a caution block, and if the actual speed of the train is too high as compared with a permissive speed set up by suitable cams, operation of which is initiated near the entrance to such sections. The reference character 20 represents a shaft driven from one of the axles shown in Fig. 1 in any suitable manner, on which is contained a centrifugal speed responsive device or centrifuge C. This centrifuge C may take any desired form; and in the simple conventional manner in which it has been illustrated, comprises a grooved collar 21 which is slidably mounted on the shaft and is adapted to be moved endwise on this shaftin response to centrifugal. force acting on the fly balls or weights 22 in opposition to the compression spring 23, this spring tending to hold the weights near the shaft. Near the centrifuge O, and mounted for rotation in journals 24, is a speed shaft 25 to which is keyed an arm 26 having its free end bifur-' cated and containing inwardly extending pins straddling the grooved collar 21 with the pins engaging the groove, so that the shaft 25 assumes a position corresponding to the speed of the train as manifested by the position of the collar 21 on the shaft 20. To the shaft 25 is pinned a speed cam 29 having a pair of contacts 30 associated therewith, the movable contact of which is pro vided with a roller 31 engaging the surface of the cam 29. These parts are so related with respect to each other that the contacts .80 are brought into contacting relationship when the speed as indicated by the centrifugeC is below 20 miles per hour.v

As heretofore mentioned, the present system of train control includes two separate speed-distance cams adapted to be driven from the wheels of the railway vehicle through different, sections depending on the character of the tra'ckway current in such sections. Two such cam controlling mechanisms have been illustrated in Fig. 2, and

since these are essentially the same, except as to the shapes of the various camsemployed, the description of one of these mecha nisms will suffice for both, and like parts of the other mechanism will be indentified by the same reference characters having distinctive exponents.

Referring to Fig.2, to the shaft 20 driven from the car wheels is pinned a Worm 33, which meshes with a worm wheel 34 pinned to al shaft 35, supported for rotation in journals 36.- On this shaft 85 is ikeyed a pinion 37 meshing with a gear 38 which is supported for rotation on a pin 39. This pin 39 also forms a bearing support for the bifurcated end of an arm 40 of a cam starter mechanism HOS used to control the high to medium cam HG. In the bifurcated portion of this arm 40 is pivotally supported a pinion 41, which is in continuous meshed re lation with the gear 38. The free end of this arm 40 is spring-pressed upwardly by a compression spring 42, guided by a .rod 43 fastened in a stationary lug 44. Under normal clear traffic conditions, the arm 40 is held in its lower position as shown by the cam starter magnet HUS which is then energized and attracts the armature 45 fastened to this arm 40. Directly over the. pinion 41 is a distance cam shaft 47, supported in journals 48, and having a multilatcd gear 49, a pinion 50, the cam HQ, and a distance cam 51 pinned thereto. The multilated gear 49 has a portion thereof cut away, so that when the cam starter magnet HCS is deenergized and the spring 42 moves the pinion 41 into engagement with this mutilated gear, this mutilated gear 49 may be turned only through an angle of substantially 180, after which no further turning takes place by reason of this mutilated portion.

The shaft 47 is held in its normal position as shown by a suitable spring returning mechanism, which in the particular arrange ment shown, comprises a sector 53 pivotally supported on a pin 54 and held in its normal position by the opposing springs 55 between the lugs 56 and the arm of the sector 53. This sector 53 meshes with the pinion 50 on shaft 47 and holds the shaft 47 in the normal position with the mutilated'portion of the gear 49 rotated 180 degrees from the pinion 41.

The cam 51 heretofore mentioned may be convenientlycalled a distance cam, because it is adapted to make and break circuits depending on the distance the train has moved after the cam starter magnet HCS has been de-energized. As shown, this distance cam 51 maintains the contacts 58 closed so long as the roller 59 is 011 either of the elevated portions of this cam 51.

In order to operate a contact when the speed, as indicated by the centrifuge C, is

too high as compared with the permissive speed set up by the high-to-medium speeddistance cam HG, a floating lever mechanism is employed, which includes a speed arm 60 having its free end pivotally connected to the lower end of a floating lever 61. The upper end of the lever 61 has a roller 62 engaging the edge or cam surface of the cam HG. I It is thus noted that any intermediate point on this floating lever 61 responds both to the speed of the train as well as the position of the cam HO, and all that is necessary, in order to control a circuit when the actual Speed is too high as compared with the permissive speed set up by the cam HC, is to operate a switch in response to the position of such intermediate point. In the arrangement shown, this mechanism comprises a sector 63 pivotallysupported on a pin 64 having a pin 65 eccentrically located therein, to which is pivotally secured a link 67 having its other end connected at an intermediate point by a pin 66 to the floating lever 61. This sector 63 is urged in a counter-clockwise direction by a spring 68 and in turn urges the roller 62 against the cam H0. The sector 63 is so shaped that, when turned in a clockwise direction through a certain degree or angle, the contacts 110 open.

Fig. 3 of the drawings shows a circuit ar *angement of the car-carried apparatus, including the mechanism of Fig. 2 and certain other devices in their normal clear traffic conditions with the train running at a speed somewhere between the medum and maximum speed adapted to be set up, which apparatus will now be briefly described.

For reasons more clearly pointed out hereinafter, it is desirable to provide an acknowledging device which the engineer may operate to show his alertness; and, on account of the fact that such an acknowledging act should not be required until after the train has run a certain distance in more restrictive territory, in order to obviate necessity for acknowledgment on account of dead-sections, this acknowledging device is preferably so constructed that it need only be momentarily operated. In the arrangement shown, a plunger 70, having a return spring 71 and contacts 72 and 7 3, is provided with an armature 74, which can be held down in opposition to the spring 71 by energization of either of the windings 75 and 76.

One of the essential elements of any train control. system is a suitable means for effecting a brake application by the usual air brake mechanism under certain predetermined conditions. Since the present invention relates more particularly to means for actuating said brake applying mechanism and does not relate to the mechanism itself, no particular form of brake control device has been shown. It contemplated that such brake applying device be operated pneumatically; and an electro-pneumatic device EPV which is electrically controlled has been shown for this purpose.

As heretofore mentioned, it is desirable to give the engineer adequate. information so that he may control the train without having a penalty inflicted upon'him if he is vigilant and alert" in attending to his duties, and for this purpose four distinctive types of cab signals havebeen provided. These signals may first be divided as visual signals, or audible signals. The visual signals Y, NOS, B; and G have been shown by the 7 preferably used to indicate a change to, orv

circles and preferably comprise suitable incandesccntlamps or light signals. The audible signals have been shown bysquares and are of three different types. The first type,

type of audible signal is one that is momen tarily sounded when it is being energized and 18 again momentarilysounded when it is being de-energized. This third type is from, clear, caution and danger, respectively; and a signal of this type is connected in multiple with the green, yellow and red lamps G, Y and R. The single and double stroke audible signals just mentioned preferably consist of the usual type of single stroke electrical gong. If the gong is to be sounded only when it is energized, it is placed on the tractive side of the armature;

if it is to be sounded when it is de-energized,

the gong is placed onthe retractive side of the armature; and 1f 1t is to be sounded both when it is energized and when 1t 1s de-energized, two gongs are used placed one on each side of the armature.

Operation.

In reviewing the operation of the car-carried mechanism shown in Fig. 3no particular reference will be made to the trackway a1i )pai'atus, it being understood that a change from normal phase relation to reverse phase relation of trackway current encountered by a moving train causes the main relay MB to assume the reverse position, and that the presence oi one kind of current only, or no current, on the trackway causes this relay to assumcits tie-energized position.

The circuits interconnecting and controlling the various parts of the car equipment are shown in Fig; 3 in a simplified and dia-.

grammatic manner. The'source of energy is illustrated a battery 100, which may, however, be a turbo-generator or other suitable source of electrical current. 80 at the left hand side of Fig. 3 is connected to one terminal of the battery 100, assumed to be the positive terminal, and is called the positive bus. The other wire 90 at the right hand side of Fig. 3 is connected to the negative terminal. Thevarious speed contacts areshown one above the other and are connected by a dot-and-dash line representing the speed shaft 25 2) The speeds at which the several speed contacts open or close are'indicated by figures. The various distance contacts, controlled by the cam starter magnet HCS, are illustrated as oper- The wire ated by cam members connected by a dotand-dash line representing the shaft 47. Similarly, the distance contacts operated by the cam starter magnet LCS are shown connected by a dot-'and-dash line. The several cont-act fingers or armatures operated by the relays A070, PR and N C, are shown below the conventional representation of the relay winding and are connected by dash lines,

In order to understand the circuit arrangement in Fig. 3, it is considered expedient to traceall of the important closed circuits first, after which changes in these circuits and devices may be readily considered and understood.

, The control circuit for the normally energized penalty relay PR may be traced as follows :-beginning at the positive bus 80, wire 81, distance contacts 82, wire 77, distance contacts 83, wires 84 and 85, front con tact 86 of penalty relay PR, wires 87 and 88, winding of the penalty relay PR, wire 89 to the negative bus 90. There is still another circuit for energizing this relay PR, namely, the circuit including the contact 13 of the relay MR, and the purpose for this latter circuit and the parts included therein, arepointed out more particularly hereinafter. I

The circuit forenergizing the cam starter magnet HCS may be traced as follows beginning at the bus 80, wire 91, contact 92 of the main control relay MR, wires 93 and 94, Winding of the cam starter magnet HCS, wire 95, back contact 97 of the acknowledging relay A076, wire 98, back to the negative bus 90 of the battery 100.

The circuit for the :u'iedium-to-low cam starter magnet LCS may be traced as follows :beginning at the bus 80, wire 101, contact 102 of the main relay MR, wires 103 and 104, winding of the low cam starter magnet LCS, wire 105, back contact 96, wires 106 and 98, t0 the negative bus 90. I

A normally closed circuit for the brake control device EPV may be traced as follows :-beginning at the bus 80, wire 109, cam governor contact 110,- wires 111 and 112, distance contacts 113, wires 114, 115 and 116, frontcontact 117 of the penalty relay PR, wires 118 and 119, front or stick contact 120 of the device EPV, wires 121, 122, 123, winding of the device EPV, wire 124 to bus 90. It should be noted. that the device EPV is normally made non-stick because stick or front contact 120 is shunted by a partial circuit including the wires 125, 127 and 129 and the contacts 58 and 58 Beforetaking up the actual operation of the system under different traffic conditions, let us assume that the main relay MR changes from its normal position as shown to its de-energized position, as would ordinarily occur when a train passes a so-called dead-section. This causes the high tomedium cam starter magnet HGS and also the medium-to-low cam starter magnet LGS to be de-energized, thereby initiating both of these cams. Let us assume that a distance of, say 200 feet, will be the longest dead-section encountered in practice. The cam HG is preferably so shaped that the permissive speed set up by this cam HG is not reduced during this distance of movementl Also, it the main relay MB is not de-energizedfor ,a greater distance than 200 feet of movement, no acknowledgement is re quired by the engineer, because the energizing circuit for the penalty relay PR here tofore traced and including contacts 82 and 83 is not broken until the train has traveled for a greater distance than 200 feet under the assumed condition. If the train were to travel more than this distance under the assumed condition the opening of distance contacts 82 or 83 would break the stick circuit for the relay PR.

In short, the system of this invention is so organized that there is no change in the speed limits enforced, nor an automatic brake application due to failure to acknowledge, upon de-energization of the main car relay MR, until after a certain limited distance of travel which is selected so as to be longer than the longest deadsection distance encountered on the railroad. On account of this distance lag, it is not necessary to provide currents at all points along the trackway to influence both sets of receiving coils on the locomotive, thereby avoiding the need for wires near the track rails to maintain energization of the car relay at crossings, the frogs of switches, and staggered 1o1nts.

Mam'mam speed Zimit.-A continuing maximum speed limit, assumed to be 60 miles per hour in this instance, is enforced under clear tratlic conditions. Even with the cam HG in the initial maximum speed position, as shown in Figs. 2 and 3, it will'be evident that the running speed of the train cannot exceed a predetermined amount, corresponding to the minimum radius of the cam, without moving the floating lever 61 far enough to open the contacts 110 and apply the brakes. Since the contacts 58 and 58 are closed, the cams HG and LG being in the initial position, the valve EPV is connected non-stick; and as soon as the running speed of the train is reduced below the maximum speed limit, the yalve EPV is automatically re-energized, and the engineer may release the brakes and proceed. The engineer is aided in running at the highest speed consistent with safety without an automatic brake application by a warning signal as hereinafter explained.

E uteri 1m caution bZ0ck.-Let us now assume that, by reason of entering a caution block, the main relay MR is changed from its normal position, as shown, to its reverse dotted positlon. Thus change of the relay MR de-energizes the cam starter magnet HGS and causes the high-to-medium cam HG to be geared to the wheels of the vehicle and gradually rotated about its axis and for the same reason gradually rotatesthe distance cams 51, 130, 131 and 132. As this high-t0- medium distance shaft 47 is rotated, the contacts 133 are closed and remain closed for a distance of, say 300 feet. As soon as contacts 133 close, depression of the push button will cause it to be held down in its depressed position by reason of the energization ofwinding 7 6 through the circuit readily traced in the drawings through the contacts 133. This winding 76 is so designed that it is capable of holding the armature 7 1 down, if it is depressed, but is not able to pull the armature into its depressed position. By reason of this construction the engineer need not hold down the plunger or push button 70.

With this acknowledging plunger 70 held down as, just explained, a circuit for the acknowledging relay A020- is completed through the contacts 72, which can be readily traced in the drawings. With this acknowledging relay A07: energized, an auxiliary stick circuit for the penalty relay PR is completed and may be traced as follows beginning at the positive bus 80, wire 135,

front contact 136 of the acknowledging relay Ack, wires 137 and 85, front contact 86 of the penalty relay PR, wires 87 and 88, winding of this relay PR and wire 89 back to the negative bus 90 of the battery 100.

When the train has traveled a distance of about 250 feet, the contacts 83 operated by the distance cam 131 are opened for a short distance of travel only. Since, however, as just explained, an auxiliary circuit has been completed for the penalty relay PR, this relay is not de-energized by opening of the contacts 82. A short distance after the contacts 83 temporarily open, the contacts 133 open and de-energize the winding 76, permitting the plunger 70 to be returned to its upper position by the spring 71. This opens the contacts 7 2 and causes de-energization of the acknowledging relay A070; but since the contacts 83 are now closed, the penalty relay PR is maintained energized by its normal stick circuit.

' If the engineer has been asleep, is dead or has not takenvcare of his duties for some other reason, as would be evidenced by his failure to operate the acknowledging button, this penalty relay PR would be de-energized upon opening of the contacts 83. Such deenergization of the stick penalty relay PR causes an immediate brake application, because the main circuit for the device EPV includes a front contact of this relay PR.

Also, since the penalty relay PR is a stick relay, if once de-energized, it remains in its de-energized position until the train has been brought to a stop or substantially zero miles per hour, whereupon a pick up circuit for the penalty relay PR is completed which may be traced as follows :beginning at the positive bus 80, wire 139, contacts 140 and 143, wires 144 and 88, winding of the penalty relay PR, wire 89, to the negative bus 90.

As the train travels through a caution block, assuming acknowledgement on the part of the engineer, the high cam HO turns and imposes a gradually reducing speed limit indicated by the curve a in Fig. 1. If the train in time exceeds this speed limit, the contacts 110 open and de-energize the electro-pneumatic valve EPV. Since the contacts 58 are now open, the shunt around the front contact 120 of the valve EPV is broken, so that whenever the valve EPV is tie-energized by excessive speed under caution traffic conditions, it cannot again be re-energized until the contacts 58 re-close except for the contacts 1l014:1 described hereinafter. Hence, if the engineer does not control his train properlyand exceeds the permissive speed limits set up by the cam HG, the brakes are applied and cannot be released until the speed of the train has been brought down below the intermediate or medium speed.

After the train has traveled part way through the caution block, the cam shaft HC is turned to a point where the pinion t1 rotates idly in the mutilated portion of the gear 49, holding the cam in this intermediate or sub-maximum speed position. The train may continue at any speed less than this medium speed, assumed to be tO milesper hour, until the point B, at which the balancing resistance 7 is located, is reached. If the train exceeds this medium speed limit, the brakes are automatically applied, but can be released as soon as the speed has been reduced below this limit,'since the contacts 58 are closed.

As the train passes the point B in the caution block, the fingers of the main car relay assume the middle or neutral position, the finger 102 breaking the energizing circuit for the cam starter magnet LCS. The cam LC is now connected to the wheels of the vehicle, and after the train runs for a short distance longer than the dead-section distance, the contacts 113 open, breaking a shunt including wires 112, 114 and 115 around the contacts 110, so that these contacts 110 of the cam LC are in control of the valve EPV and will act to de-energize this valve if the train exceeds the permissive speed limits set up by this cam. Contacts 58 open soon as the shaft of the cam LC starts and makes the valve EPV stick. Consequently, if the train exceeds at any point the permissive speed limit set up by the cam LC, indicated by the curve?) in Fig. 1, the brakes cannot be released until the train has been brought to a stop, at-which contacts 140-141 close, or until the contacts 58 are re-closed. Before the train reaches the end of the block, the cam LC reaches'its minimum speed position, the pinion 41 1o tating idly in the mutilated portion of the gear 49 After the train has advanced beyond the point B in a caution block to a point selected to be braking distance for the minimum speed from the eXit end of the block, the contacts 1416 close, establishing a circuit for the acknowledging signal Aclc. S, running from positive wire 80, contacts 146, contact finger 73 and front contact of the acknowledging device 70, signal A072. S to negative wire 90, and also energizing the upper winding 75 through a circuit obvious from the drawing. Upon giving of this acknowledging signal, the engineer is supposed to operate the acknowledging contactor 70, opening the contacts 7 3 to stop the signal and closing contacts 72 to energize the acknowledging relay A070. The energized winding 75 holds the plunger 70 of the acknowledging c011- tactor in its lower position in the same way previously described, until the contacts 14-6 open. After a short distance of further travel, sufficient to afford the engineer opportunity to manipulate his acknowledging contactor and energize the acknowledging relay A070, the contacts 82 open and make a break v 'in the normal stick circuit for the penalty relay PR. Since the acknowledging relay A070 is energized, proper acknowledgment being assumed, the penalty relay PR is held up by its auxiliary stick circuit, and no brake application occurs. It will be evident'that, if the engineer failed to acknowledge, the penalty relay PR would be de-energized,

applying the brakes and maintaining them applied until the train had been brought substantially to a stop and the contacts 14() 143 closed. 1',

It will be noted. that the acknowledging signal A070. S is automatically given before acknowledgment is required of the engineer near the end of the caution block, in recognition of the danger or stop signal, and that this acknowledging signal is given after passing the caution signal. This arrangement is adopted on the theory that the en gineer'can tell from the caution indication and location of the block signal when to make his cautionary acknowledgement. The acknowledging point for the stop signal, however, will in practice be somewhat variable, due to wheel wear, diiferences in a grade, or the like; and while a suitable marker along the track (not shown) might be used to indicate the point of acknowledgment, it is preferred to operate the acknowledging signal, which will always be a short ill interval of distance in advance of the actual point of acknowledgment and will atl'ord the engineer reasonable opportunity to act in every case.

In connection with the acknowledgment required of the engineer, it should be noted that no acknowledgment is required at a caution signal when the speed is less than 20 miles per hour, since the speed contacts 7 8, closed below 20 miles per hour, shunt the contacts 83. Acknowledgment for each stop signal is required irrespective of the speed, since opening of the contacts 82, with the main car relay MR de-energized, breaks the normal stick circuit for the penalty relay PR and would result in de-energization of this relay and a brake application, unless the acknowledging relay A070 were energized.

If the engineer should attempt to defeat the purpose of the system and avoid acknowledgment by tying or fastening down the acknowledging contactor 70, the resultant energization of the acknowledging relay Ada, by opening back contacts 97 and 96 of said relay, would tie-energize both of the cam starter magnets HCS and LCS, resulting ultimately in the enforcement of a minimum speed, which would serve to deter the engineer from attempting to avoid acknowledgment in this way.

If the block in advance should become unoccupied at any time while the train is travelling in a caution block, the contact lingers of the main car relay MR would assume the normal position shown in Fig. 3, thereby V energizing both of the cam starter magnets and returning the cams to the normal initial position; there is a momentary opening of thecontacts 82 and 83, and to avoid de-energization ot the. penalty relay PR under such conditions, this relay is held up by a circuit through the normal contact of the finger 13 of the main car relay MR, as already indicated.

Entering a danger bc7c.As the train passes from a caution to a danger block, there is no change in the car equipment. The main car relay remains tie-energized and the cams HC and LC in their run down positions; A minimum speed limit is maintained throughout the danger block.

It a danger block changes to a caution block, while the train is to the rear of the point B, the contact fingers of the relay MR assume the reverse position, returning the cam LG to the normal position, but not the cam HG. During this return movement of the cam LC, the contacts 82 are shunted by the reverse contact of the finger 13 of the relay MR. If the train should be in advance of the point B, when the block changes from danger to caution, no change in the car equipment takes place, the car relay MR remaining tie-energized.

Open switch and broken mil pr0te0te'0n. In the continuous inductive control type of system, the relay MB on a train is at all times responsive, not only to the track circuit oi the block next in advance, but to the presence of a train in the same block, the conditions of the switches, and the integrity of the track rails. If a switch should be opened in advance of a train in the same block, or a. rail break, or another train back into that block, the car relay MR would be de-energized and the lou speed cam LO immediately started, bringing the speed of the train down to a minimum speed. It the train is travelling at a high speed at the time of such sudden danger condition, an immedi' ate brake application occurs, because as soon as the cam LC starts, the medium speed limit is effective.

Gab signaZs.Under normally clear trailic 7 conditions of the apparatus as shown, a green cab signal G indicating clear traiiic conditions is displayed, being energized through a circuit from the negative wire 90, signal G, contact tinger165 and back contact of relay NC, contact linger 92 and normal contact of relay MB, to positive wire and with this visual signal there is also associated a two stroke audible signal 9, this audible signal sounding both when the lamp G is being lighted and extinguished but does not sound while this lamp is illuminated. As the main relay l IR changes from its normal to its reverse position, the clear lamp G is extinguished with a single tap' of a bell or the like, and the yellow lamp Y is illuminated through a circuit including wire 90, signal Y, finger 92 in reverse position, and wire 80, with a similar tap by the audible signal 3/. Similarly, the change from the reverse to the ale-energized position of the main relay MR causes the yellow lamp to be extin guished, sounds the audible signal y with a single tap and causes the danger signal R to be displayed through a circuit including, wire 90, signal It, finger 159 and back contact of relay NC, wire 158, finger 157 of MB in tie-energized position, and wires 156 and 80, and also sounds the audible signal 9* with a single tap, so that three distinct audible signals are given when the traiiic conditions change as evidenced by the main relay MR.

Non-control term'tory.-As heretofore mentioned, when a train runs into territory which is not equipped for train control purposes, no trackway current is available, certainly not in two different circuits which have a phase relation so as to cause response of the main relay MR on the train; and without provision to the contrary, the train would be required to travel at its minimum speed with the low cam in its ultimate position In order to permit movement of the train at a higher speed, and also to advise the engineer that he is running in non-traincontrol territory, a non-train control relay NC is provided. This relay NC is connected in circuits with contacts operated by the main relay MR so that when the main relay changes from clear to danger, that is, from the normal energized position to the deenergized position, itbeing understood that at the entrance to non-train control territory the tracks are constantly furnished with line and track phase currents to provide clear track conditions for a short distance, this relay NC may be picked up and stuck up, providing the engineer operates the acknowledging push button 70.

Let us assume that a train is running in clear territory but is just about to enter territory not equipped for train control purposes. As the engineer operates the push button 70, a pick-up circuit for the relay NC is completed as follows F-beginning at the positive bus 80, wire 91, contact 92 of the main relay MR, wires 93, 150 and 151, front contact 152 of the acknowledging relay A070,

wires 153 and 15 1-, winding of the relay NC,

wire 155 to the negative bus 90. It is desired to point out that operation of the acknowledging push button upon a changed from clear to caution traffic condition illuminates the non-control signal lamp NCS due to energization of the relay NC only in the event that the push button is depressed before the main relay MR has changed from its clear to its caution position. This is, however, not the contemplated operation of the system, the engineer not being supposed to operate the push button 70 until the relay has already assumed the caution position. It the engineer does depress the ush button 70 before the relay MR changes From clear to caution the relay NC may be picked up and temporarily stuck up through contact 165, but in this event the caution. lamp Y is illuminated as soon as the main relay MR changes from clear to caution, thus giving the engineer two conflicting signals which, of course, will indicate to him that he is not operating in non-control territory.

.lVith the relay NC energized through its pick-up circuit for reasons just given, a change of the main relay MR from its normal to its de-energized position completes a circuit for this relay which may be traced as follows :beginning at the positive bus 80, wire 156, contact 157 of the main relay MR, wire 158, contact 159 of the relay NC, wires 160, 161 and 154, winding of the relay NC, wire 155 to the negative bus 90.

lVith this relay NC energized by this stick circuit, a circuit for illuminating the non-train control signal NCS is completed which is readily traced in the drawings. lVhen this visual non-control signal NCS is being energized, no sound of the audible signal associated therewith is given, but such a sound is given when this relay is again deenergized, this occurring when the train reenters signal territory and causes the main relay MB to be picked up in either the normal or reversed position thereby breaking the stick circuit for this non-control relay NC. It is desired to point out that if a train re-enters signalled territory after having moved in non-control territory, that the non-control signal lamp NCS will not be extinguished even though the train is movwith traffic conditions existing ahead of the train as it should in train control territory. With the non-control relay NC in its energized position the following circuits are completed for energizing the cam starter magnets HCS and LCS, respeetively:- (l) beginning at the positive'bus 80, wires 101, 163 and 164, front contact 165 ofthe relay NC, wires 166, 150 and 94, winding ofthe cam starter magnet I-ICS, wire 95, backcontact 97 of the acknowledging relay A c/s (the engineer having released the push button 70), I

wire 98 to the negative bus 90; and (2) beginning 'atthe positivebus 80, wires 101, 163 and 167, front contact 168 of the relay NC, Wires 169, 10 1, winding of the cam starter magnet LCS, Wire 105, back contact 96 of the relay A070, Wires 106 and 98 to the negative bus 90.

Warning signaZ.-Referring to Fig. 1, the shaded areas represent sections in a caution block where an audible signal is given between certain speed limits. If the train enters a caution block, the engineer knowing that he must reduce his speed until an audible signal is given properly reduces the the speed, as a rule. As he reduces the speed in this manner the Warning signal finally sounds and tells him that he has now reached a speed slightlyhigher than the minimum permissive speed setup by the high cam which has been shown as 4L1 miles per hour, and he is required to reduce his speed still a little further to, say '39 miles per hour to discontinue sounding of the warning signal WV shown in Fig. 3. Similarly, when the medium to low cam LC is initiated the engineer is required to reduce his speed to, say 19 miles per hour, and in doing so an audible signal is sounded between the speed of 21 and 19 miles per hour.

The circuit for sounding the warning signal W through the top shaded areain 1 niaybe traced as follows :-beginning at the positive bus 80, wire 109, governor cam contacts 110, wires 111 and 11 2, distance contacts 113, wires 114:, 170, 171 and 172, 58

M. P. H. contacts 173, wires 17 1 and 175, conning in non-train control territory) wire 177,

winding of the whistle WV, wire 178 to the negative bus 90.

When the high-to-medium cam has been initiated and the train has run the acknowledging distance of, say. 300 feet the distance contacts 180 are closed and a circuit is completed which is closed between 39 and ll miles per hour for sounding the warning signal W which may be traced as follows beginning at the bus 80, wire 109, governor cam contacts 110, wires 111 and 112, distance contact 113, wires 114;, 170 and 181, speed contacts 182 closed between speeds of 89 and 411 miles per hour, Wire 183, distance contacts 180, wire 18 1, distance contacts 185-186, wires 187 and 175, contact finger and back contact 176 of the relay NC, wire 177, winding of the whistle W, wire 178 to the negative bus 90.

As soon as the low cam is initiated by de-energization of the cam starter magnet HUS, the distance contacts 185 and 186 oper ate, thereby discontinuing sounding of the audible signal between the speed of 39 and 41 miles per hour, and closing contacts 185 and 188 which complete a circuit for the audible signal W when the speed of the train is between 19 and 21 miles per hour, as follows :beginning at the positive bus 80, wire 109, governor. cam contacts 110, wires 111 and 189, governor cam contacts 110 of the medium-to-low cam, wires 191,. 115, 170, 171 and 192, speed contacts 198 closed between speeds of 19 and 21 miles per hour, wire 19 1, distance contacts 188 and 185, wires 187 and 175, contact finger and back contact 176 of the non-control relay N C, wire 177, winding of the whistle W, wire 178 back to the negative bus 90.

It should be noted that when the high-tomedium cam is gradually changed from its normal to its ultimate position the circuit referred to, which is closed between .39 and 11 miles per hour, is broken as soon as the speed set up by the cam governor contacts 110 is exceeded, that is, thewarning signal does not respond between these speeds when contacts 110 are open; and likewise, when the mediumto-low cam is being driven to its ultimate position, no warning signal is given between 19 and 21 miles per hour when the governor contacts 110 are open.

The various distances and speed referred to in connection with the warning signal are of course only arbitrary values which have been selected for illustrative purposes only, and it is to understood that the exact speed values given need not be adhered to and that the warning signal given to inform the engineer when he has sufliciently reduced the speed of the train upon initiation of the high-to-medium cam HC, is given by sounding the warning signal or whistle 7 between thespeeds of 39 and 41 miles per hour, that is, just a little above and a little below the minimum speed, which has been assumed to be 40 miles per hour. Instead of sounding the warning signal in a caution block between these speed limits only, it may be sounded whenever the speed is above this medium speed value; and in Figs. at and 1A. has been shown an arrangement in which a warnng signal of this character is given. 7 Referring to Fig. 4, the shaded area represents the various speeds through various sections in a caution block at which the warning signal W is sounded. It will be noted that it is sounded above 58 miles per hour the first 300 feet in the block, well as in every clear block, is sounded above the speed of 39 miles per hour from this point to the point B (balancing resistance 7), and is sounded above the speed of 19 miles per hour from the point B to the end of the block.

In Fig. 4A has been shown a car-carried circuit arrangement, similar to that shown in Fig. 3, in which the control for the warning signal \V has been modified to sound this signal in a manner as indicated by the shaded area in Fig. 41. The high and low cams HO and LC, respectively, represent similarly designated devices shown in Fig. 3, this also being true of the distance cam 130, the penalty relay PR, the non-control relay NC, the warning signal V7, and the electro-pneumatic brake control device EPV; and these devices, except the warning signal W, are also con trolled in the same manner as are those of Fig. 3. The apparatus shown. in this modified form of the invention is illustrated in its normal clear trailic condition, with the vehicle running at a speed somewhere between 39 and 58 miles per hour. The brake control device EPV is energized through a circuit which has already been traced in connection with the description of Fig. 3.

Operation of Fig. 4A.Let us assume that a train is running in the block I in Fig. 1 when this block I is in a caution traflic condition because the block J next in advance is occupied by another train. As the train proceeds into the block I, the high camllC is initiated for reasons given in connection with the description of Fig. 3, and during the travel of the first 300 feet, as well as when the train is moving in clear territory, a circuit is closed for sounding'the warning signal 1V if the speed is above 58 miles per hour which may be traced as follows beginning at the bus bar 80, wire 109, cam governor contacts 110, wires 111 and 195, contacts 196 and 197 of the distance cam 198 on the low cam shaft, wires 199, 200 and 201, speed contacts 202 closed above 58 miles per hour, wires 203 and 204, back contact 205 of the non-control relay NC, wire 177, warning signal 1V, wire 178 back to the other bus bar 90. 1

After the train has traveled a distance of 300 feet, the distance cam 130 closes its contacts 180 and completes the following circuit for sounding the audible warning signal 1V, providing the train is moving above a speed of 39 miles per hour ;-beginning at the positive bus 80, wire 109, cam governor contacts 110, wires 111 and 195, distance contacts 196 and 197, wires 199, 200 and 206, distance .contacts 180 closed 300 feet after the high cam has been started, wire 207, speed contacts 208 closed if the speed of the train is above 39 miles per hour, wires 209, 210 and 204, back contact 205 of the relay NC, wire 177, winding of the warning signal 1V, wire 178 to the negative bus 90. 7

It is thus noted that the warning signal is sounded until the train speed has been reduced below 39 miles per hour. When the train passes the point B at the balancin resistance 7, the main relay MRis de-energized, thereby de-energizing the cam starter magnet of the low cam LC and initiating movement of this cam. After the train has traveled a short distance of, say 200 feet, the distance contact 197 moves to the ultimate left-hand position and closes a circuit for sounding the warning signal W for all speeds above 19 miles per hour which may be traced as follows :beginning at the bus 80, wire 109, cam governor contact 110 of the high cam HG, wires 111 and 189, cam governor contact 110 of the low cam LC, wires 191, 211 and 199, distance contacts 197 and 212, wire 213, speed contacts 214 closed above 19 miles per hour, wires 215, 210, 204, back contact 205 of the relay N C, wire 177,

warning signal W, wire 178 back to the other bus 90.

By the provision of a warning signal oper ating in a manner just described the engineer is continually reminded of the fact that he must reduce his speed until the warning signal stops, so that the engineer has had adequate information enabling him to avoid the penalty which is inflicted if he allows an automatic brake application to take place.

i lzorZ ificat'ion-s' of warning signal F 5 and 5A.Again referring to the shaded area in Fig. 1, it should be noted that, if the train is moving at less than 29 miles per hour when entering a caution block, no warning signal of any kind is given. -Although it form the engineer that he is actually below this medium speed. In Fig. 5 has been diagrammatically illustrated by shaded area how a warning signal may be sounded when the train enters a certain section, even if this 7 train is traveling at a speed lower than that enforced at the exit end of such. section, this sounding of the warning signal being accomplished by closing an energizing circuit therefor, for a short distance of travel of the train, regardless of the speed of the train upon entering such section.

In the modified circuit arrangement shown in Fig. 5A, the warning signal W is not sounded at any time in a clear block, regardless of the speed at which the train is running. As the train enters a caution block, movement of a high cam HC is initiated and after a distance of, say 300 feet, a circuit is closed for a short distance of travel effective at all speeds below 41 miles per hour, for sounding the warning signal 1V, this'circuit being traced as follows :beginning at the bus 80, wire 109, cam governor contacts 110, wires 111 and 195, distance contacts 216 and 217, wires 218 and 219, distance contacts 180 closed after the train has traveled a distance of 300 feet with the high cam initiated, wires 220 and 221, contacts 222 closed at all speeds below 41 miles per hour, wire 223, contacts 224 closed during a distance of, say 50 feet of travel of the train after contacts 180 have been closed, wires 225, 226 and 204, back contact 205 of the non-control relay NC, wire 177, warning signal W, wire 178 back to the negative bus 90.

Also, after the train has passed this point in its travel in a caution block, a circuit for sounding the warning signal W is closed between the speeds of say 39 and 41 miles per hour, which is the same as the circuit just traced, except that the pairs of contacts 222 and 224 are shunted by a partial circuit as follows :--contacts 227 closed between the speeds of 39 and 41 miles per hour and wires 228 and 229.

When the train passes the point B in a caution block, the low cam LC is initiated, and a short distance thereafter of, say 200 feet, a circuit for sounding the warning signal for a distance of about 50 feet, if the speed of the train is less than 21 miles per hour, is completed and may be traced as follows :beginning at the bus 80, wire 109,

cam governor contacts 110, wires 111 and 189, cam governor contacts 110 of the low cam LC, wires 191, 230 and 218, distance contacts 217 and 231, wires 232 and 233, contacts 234' closed below 21 miles per hour, wire 239, contacts 235 closed for a distance of, say 20 feet,

wires 236 and 204, back contact 205 of the non-control relay NC, wire 177, warning signal Vi, wire 178 to the negative bus 90.

Another circuit, which closed for all train speeds between 19 and 21 miles per hour, is completed so long as the low cam is not restored and may be traced as follows :beginning at the bus 80, wire 109, cam governor contacts 110, wires 111 and 189, cam governor contacts 110, wires 191, 230 and 218, distance contacts 217 and 231 controlled by the low cam, wires 232 and 237, speed contacts 238 closed between train speeds of say 19 and 21 miles per hour, wires 229, 226 and 204, back contact 205, wire 177, warning signal lV, wire 178, back to the other bus 90.

From the foregoing description, it is noted that when a train is moving into a caution block, an audible signal is given for a short distance at least, providing the speed of the train is less than the minimum speed eventually enforced in the zone or section in question. In other words, in the block I illustrated, there are two sections, through the first of which the high cam moves from its normal to its ultimate position, and the second section through which the low cam is moved from its normal to its ultimate position; and a train cannot pass through either section without incurring either an automatic brake application or an audible signal, so that the engineer knows that if he reduces his speed until the audible nal is sounded and again discontinues sounding, he is not exceeding the permissive speed limits at any time.

' Modification of Fig. 5.-l'.n the application of automatic train control to certain classes of railroads, it is considered expedient to leave it entirely up to the engineer as to the speed at which. the train may travel under clear tratlic conditions ahead. A system of this character in itself may not be safe under certain conditions, because the speed of the train upon entering a caution block may be so high that, even though the automatic apparatus initiates an automatic brake application upon entering such block, the train would not come to a stop or a certain minimum speed before entering a danger or occupied block. It is necessary therefore, to require the train to reduce its speed to a certain restricted speed of, say 60 miles per hour, before it enters a caution block. in Fig. 6 has been illustrated a tracliway circuit for initiating a high cam which sets up a gradually decreasing permissive speed limit between a maximum of, say 90 miles per hour, and an ultimate speed limit of, 60 miles per hour; and as the train enters a caution block, a second or low cam is initiated which gradually restricts the speed from 60 miles per hour to a minimum of,

say 20 miles per hour. It is contemplated that a train control system for a maximum speed limit in a clear block of 90 miles per hour practically leaves it up to the engineer to determine What speed the train shall run, unless this clear block is in the rear of a caution block, whereupon the train speed must be reduced to 60 miles per hour before entering such. a caution block. In other words, by providing an over lap control by the trackway apparatus, a sort of double block caution control may be setup for the car-carried apparatus. During the first block the train must come down to a reasonable speed of, say 60 miles per hour, and through the second block its speed must be reduced from this speed limit to a minimum speed of 20 miles per hour.

In Fig. 6 has been shown a trackway comprising, blocks L and M and adjacent ends of blocks K and N. The various. signals, track relays,balancing resistance and track transformers are the same as those shown in Fig. l and have been assigned like reference characters with distinctive exponents. In the arrangement shown, referring particularly to the block L, in addition to the regular track relay at the entrance to each block a distance relay D (in block L) is controlled jointly by a front contact 24% of the track relay of the lock next in advance and the -lront contact 245 of the second block in advance, as shown. This distance relay D" at a particular signal location controls the line phase current of the block next in the rear thereof, through pole changing front and back contacts 2 11 and 2 12 so that this line phase is energized by current having one relative polarity so as to manifest clear t'aiiic conditions ahead when this relay is energized, and by the reverse relative polarity when this distancerelay D is de-enerized. It should, however, be noted that the line phase currenttor any particular block is cut oil by front contact 243 of the track relay 5* (in case of the block L) of the block in advance so that no line phase current flows when the block in advance is occupied. In other words, in the arrangement shown in Fig. 6 the line phase current of one block is entirely cut off, if the block next in advance is occupied, and the instantaneous direction of current flow in such line phase current is reversed, if the second block in advance thereof is occupied.

Although the point at which the restrictive control begins has been illustrated as existing at the entrance to a block in Fig. 6, it should be understood that the invention is not limited to this particular arrangement. For instance, the high cam, as well as the low cam, may be started either before or 7 after the entrance to a block by a circuit arrangement similar to that shown 1n Figs.

17A and 17B of the application of Howe and Bushnell heretofore referred to. Similarly, the trackway apparatus shown in Fig. 1 may be modified so that the higlrto-medium cam is started either in the rear of or in advance of a block entrance if this is found necessary to properly safeguard the train or increase track capacity, respectively.

An automatic train control system has thus been devised in which the engineer is required to manifest his vigilance and observance of wayside signals or cab signals, as the case may be, by operating a suitable acknowledging device in the cab, the operation of which is only necessary after the train has traveled a certain distance after the main relay has changed from a certain position to a more restrictive position, so that a train passing over dead sections where no trackwa-y current can conveniently be applied, such as, switch frogs, staggered joints, crossings, cross-overs and the like will not require the engineer to operate such an acknowledging device. Further, vari-' ous arrangements have been disclosed for giving the engineer adequate information as to whether he has taken the necesary action to avoid an automatic brake application, so that the engineer may avoid a penalty associated with such brake application by properly reducing the speed of the train. Also, an arrangement of trackway apparatus has been shown in which the speed of the train is restricted in the last clear block in the rear of the danger block so that it is assured that an equipped train can only enter a caution block at a speed which assures stoppage of the train in such caution block as a result of an automatic brake application upon entering such block.

Having thus shown and described several specific embodiments of the invention, it is desired to be understood that this has been done for the purpose of clearly disclosing the invention rather than for the purpose of showing the scope thereof, and that various changes, additions and modifications may be made to adapt the novel train control system to any one of the various types of railway systems encountered in practice, without departing from the nature or scope of the invention or the idea of means underlying the same.

What is desired to be secured by Letters Patent of the United States is 1. An automatic train control system comprising a normally energized relay maintained energized in response to current flowing in the track rails ahead of the train, a normally energized brake control device, means for de-energizing said brake control device if said relay changes to indicate adverse tra-fiic conditions ahead, and manually operable means for preventing de-energization of said brake control device by said last mentioned means including a push button and means for holding said push button down for a time including an electro-magnet associated therewith.

2. An automatic train control system comprising a normally energized relay maintained energized in response to current flowing in the track rails ahead of the train, a normally energized brake control device, means for de-energizing said brake control device if said relay changes to indicate adverse trafiic conditions ahead, and manually operable means having an electro-magnet associated therewith which electro-magnet if energized is capable of holding said means in a depressed condition but is incapable of moving it into said depressed position, said manually operable means if operated timely preventing de-energization of said brake control device by said last mentioned means.

3. Car-carried apparatus for automatic train control systems comprising, a relay instantaneously responsive to a change in traffie conditions ahead, a delayed action device delayed in accordance with the progress of the train, said device being initiated in response to de-energization of said relay for governing the speed of the train as it proceeds along the trackway, means for giving an acknowledging signal by said delayed action device andv means for automatically applying the brakes if said acknowledging device is not operated in response to said acknowledging signal, and means for automatically discontinuing said acknowledging signal when said acknowledging device is manually operated.

4. In an automatic train control system, the combination of an electro-responsive device on a railway vehicle adapted to assume various distinctive positions in accordance with trafiic conditions ahead, a tapered. speed restricting means governed by said device and acting on the usual air brake system for applying the brakes of the train if the speed of the train is excessive, a plurality of distinctive visual signals each of which contin uously indicates when said electro-responsivedevice assumes a certain position, and a distinctive audible signal for each of said visual signals momentarily operated when its visual signal is energized and de-energized respectively.

5. Car-carried apparatus for automatic train control systems comprising, a permissive speed device which if initiatedsets up gradually decreasing speed limits in accordance with the progress of the vehicle along the track, an actual speed device, means acting on the usual air brake system which applies the brakes if the actual speed eX- ceeds the permissive speed, an audible signal sounded through a narrow band of speeds including the ultimate permissive speed and effective when the permissive speed device has been initiated, whereby the engineer is advised that he has sufficiently reduced his speed after he has passed through said band of speeds.

6. In a car-carried apparatus for automatic train control systems, the combination of an electro-responsive means which is adapted to indicate clear, caution and dangcr conditions ahead of the car and which is energized under clear tratiic conditions ahead by current flowing in a trackway circuit, two independent permissive speed devices one of which is initiated when said electro-responsive device changes from clear to caution and the other of which is initiated when it changes from caution to danger, the first of said devices gradually setting up more restrictive permissive speed limits between a maximum and a medium and the second setting up such speed limits between a medium and a minimum speed when initiated, an actual speed device, means for effecting an automatic application of the brakes when the actual speed exceeds the permissive speed, and means for giving an audible signal through two narrow bands of actual speeds one of which includes the medium speed and the other of which includes the minimum speed and active when the respective permissive speed devices are initiated, whereby the engineer is informed when he has sufficiently reduced his speed when changing from a maximum to a medium and when changing from a medium to a minimum speed by the sounding of the audible signal for a short period of time during retardation of the train.

7. In an automatictrain control system; the combination of car-carried apparatus comprising a high-to-mcdium variable permissive speed device, a medium-to-low variable permissive speed device, an actual'speed device, means acting on the usual air brake system and effective to apply the brakes of the train it the actual speed exceeds the lowest permissive speed set up by said permissive speed devices,. and electro-responsive means for controlling said permissive speed device; and of trackway means for control ling said electro-responsive device including means effective to initiate said high-to-medium permissive speed device at the entrance to the last clear block preceding a caution block and for initiating said medium-to-low permissive speed device upon entering a caution block.

8. An automatic train control system according to the preceding claim wherein the high-to-medium permissive speed device varies the permissive speed from a speed higher than the train should run under clear traffic conditions ahead to a high permissible speed value, and in which the medium-tolow permissive speed device sets up permissive speeds ranging from this value to a minimum speed occupied block. 7

9. Car-carried apparatus for automatic train control systems of the continuous inductive type comprising, a normally energized brake control device, a delayed action device which is adapted to be initiated from the trackway and which it initiated is delayed in its action in accordance with the progress of the vehicle along the trackway, means governed by said delayed action device for opening a circuit maintaining said device energized thereby de-energizing said brake control device through a certain distance of travel only, and manually operable means which it operated completes another and auxiliary circuit for maintaining said brake control device inactive.

10. Car-carried apparatus according to claim 6, further characterized by the proconsidered safe in an vision of means for sounding an audible signal when the train passes a certain zone when the first permissive speed device is initiated, and for sounding an audible signal when the train passes another zone when the second of said permissive speed devices is initiated, providing the speed of the train has been suliiciently reduced in each case, whereby the engineer is informed when he has sutliciently reduced the speed of the train.

11. Car-carried apparatus for automatic train control systems of the continuous inductive type, including, in combination with a main relay maintained energized under favorable traffic conditions ahead by current flowing in the track rails ahead of the train, a distance device changed in accordance with the progress of the train but normally maintained inactive, and which if initiated will be operated to an ultimate condition; a nor mally energized brake applying device which has its energizing circuit broken for a short distance of movement by said distance device a predetermined distance of travel of the train after said distance device is initiated, and also just before said distance device has reached its ultimate condition; and manually operable means for shunting the break in said circuit.

12. Car-carried apparatus for automatic train control systems of the continuous in ductive type, including, in combination with a main relay maintained energized under tavorable tratlic conditions by current flowing in the track rails ahead of the train, a distance device changed in accordance with the progress of the train but normally maintained inactive, and which it initiated will be operated to an ultimate condition; a normally energized brake applying device which has its energizing circuit broken for a short distance of travel of the train by said distance device a predetermined distance of travel of the train after said distance device is initi-

Images