US1720646A - Train control - Google Patents

Description

July 9, 1929. F. DODGSON TRAIN CONTROL Filed Nov. 20, 1

924 3 Sheets-Sheet 1 3.. mo Illllllllll Tl-l'l qww J mm AGE y 1929. F. L. oonesou 1.720.646

TRAIN CONTROL Filed Nov. 20, 1924 3 Sheets-Sheet 2 FIG.2.

July 9, 1929. 1 DQDGSQN 1,720,646

TRAIN CONTROL Filed Nov. 20, 1924 3 Sheets-Sheet 3 c 0 ml us 15 new. 81 c 4 s1.

5 p48 as so EE'V,

Patented July 9, 1929.

UNITED STATES 1,720,646 PATENT OFFICE.

FRANK L. DODGSON, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, N. Y.

TRAIN CONTROL.

Application filed November 20, 1924. Serial No. 751,120.

This invention relates to automatic train control systems for railroads and more particularly to such systems of the continuous inductive control type employing a 3-position relay on the train controllable to give any one of three different indications.

One of the principal objects of the present invention is to provide absolute stop control for enforcing obedience to stop-and-stay interlock signals, in addition to speed control for enforcing obedience to the indications of automatic block signals. In accordance with this invention, it is proposed to provide an auton'iatic brake application which occurs irrespective of the speed of the train and which can not be prevented by the engineer, whenever there is a change directly from clear or proceed to stop or danger, without an intervening change to caution. It is also proposed to provide such absolute stop control in addition to the provisions for acknowledgment of caution and permissive stop signals.

Various specific objects, advantages and characteristic features of the invention will be in part obvious and in part pointed out as the description progresses.

In the accompanying drawings, Fig. 1 shows in a simplified and diagrammatic manner the trackway equipment of this invention for automatic block signal territory, together with the impulse receiving devices and a control relay for the locomotive or other vehicle, speed-distance curves of permissive speed limits, and interrupted lines for indicating the points during the travel of the train at which certain contacts open and close;

Fig. 2 illustrates diagrammatically in perspective a simplified arrangement of operating gearing and associated parts, constituting a portion of the car-carried apparatus, this gearing and its control devices providing for the operation of speeddistance contacts, and distance contacts;

Fig. 3 illustrates diagrammatically and in accordance with some recognized and some arbitrary conventions the various parts and devices of the car-carried apparatus and their circuit connections; and

Fig. 1 illustrates how the trackivay equipment for automatic block signal territory, as shown in Fig. 1, is modified and organized to provide for reduced speed control and absolute stop upon the approach to a stop-and stav interlock signal.

A specific organization of devices and circuits, selected to exemplify one embodiment of the invention and herein shown and described, includes in some particulars structures and combinations, disclosed and claimed in prior applications filed by myself and others. For example, the specific system herein shown and described, is similar to that dis closed in the Howe application, Ser. No. 746,578, filed October 29, 1924, the present invention being in effect, generally stated a modification or adaptation of this type of system to incorporate therein the provision of it modified form of an absolute stop contro Traclcwag egm'pment.The trackway devices and control circuits for automatic block signal territory are the same as those of a continuous inductive control system of the type using a 3-position car relay, with track phase and line phase circuits. Alternating current track circuits are illustrated in the particular form shown, but it should be understood that the invention is applicable to direct current track circuits by employing the well known expedients, such as shown in the Howe application mentioned above, for applying track phase and line phase train control currents to direct current track circuits.

Referring to Fig. 1 there is shown a typical railway signaling system in which the track rails 1 are divided by insulating joints 2 into blocks, of which the block I and the adjacent ends of two other blocks H and J only have been shown. Since the various blocks are the same like parts of each block are designated by like reference characters having distinctive exponents. For simplicity it is assumed that the length of these blocks corresponds to braking distance and includes only one track circuit, various expedients (not shown) being employed to adapt the system to blocks of various lengths and those including cutsections. At the en-- trance end of the block I, the normal direction of traflic being as indicated by the arrow, is a track relay 3 of the alternating current type, this track relay being energized by current impressed across the exit end of the block I by a track transformer 4 having its primary winding connected to the secondary winding of a transformer 5 which receives its energy from a transmission line 6. Although train control systems of the three-position inductive type such as the present system, may be used in connection with trackway apparatus in which no wayside signals are used, signals of either the color light or semaphore type may be used, and for convenience semaphore signals Z of the three-position type have been shown without attempting to illustrate their well known operating mechanism and control circuits.

The apparatus thus far described is that which is necessary for wayside signal con trol purposes. In addition to this apparatus means are provided for conducting an alternating current flowing in the same direction in the two track rails in multiple and having a predetermined phase relation with the track circuit current supplied by the transformer at.

In the particular arrangement shown this simplex or line current is caused to flow through. a circuit including the two rails in multiple by applying alternating current potential to the two mid points ot balancing resistances bridged across the entrance end and exit end of the block respectively, which circuit may have its polarit reversed it the block in advance becomes occupied. This simplex or line circuit may be traced as follows:

Beginning at the secondary winding of the transformer 7 wires 8 and 9", front contact 10 of the track relay 3, wire 11, "to the mid-point of balancing resistance 12 through the two rails in multiple to the entrance end of the block 'I to the mid-point of balancing resistance 13, wire 14%, front con tact 15 of the track relay 3 wire 16 back to the secondary winding of the transformer 7. lVhen the track relay 3 is de-energized current is reversed in this circuit as is obvious by looking at the pole changer contacts 10 and 15 Referring now to Fig. 4, which illustrates a continuation of the trackway apparatus shown in Fig. 1, there has been shown the block K and the adjacent ends of the blocks J and L of which the block ii is located in interlocking territory. Since many of the parts of the trackway apparatus shown in Fig. dare the same as those shown in Fig. 1, such parts are designated by like reference characters having distinctive e.;ponents. It should be noted that the signals Z and ZA are distant and home signals respectively to the interlocking territory shown and for this reason these signals have been illustrated with square lades. The dotted rectangle shown illustrates an interlocking tower which among other things includes a lever 27 which under normal stop condition, as shown, maintains the signals Z :tHCl'ZA at the caution and stop position respectively in the absence of a train in the block K, but it the block K is occupied the signal Z will, of course, also indicate danger.

This lever 27 is suitably interlocked with levers of conflicting routes, such as, crossin sittings, etc. so that the signal ZA. which is an absolute stop-and-stay signal must assumo the danger position before the switch tor such siding may be opened or the derail for such crossing may be closed. It may be mentioned at this time that the practice heretofore has been to provide a derail just beyond a stop-and-stay signal, such as the signal ZA, which was opened when the signal was stop so as to'assure that a train would not pass such stop-and-stay signal when at danger. In accordance with the present invention it is proposed to eitect an automatic brake application regardless of. speed instead of a derailment when a train passes such a stop-andstay signal a. In addition to the balancing resistances 19. and 13 heretofore mentioned there are provided balancing resistances 2S and 29 in the block K, so that, a plurality of simplex circui are torn'ied. in order to readily see it these simplex circuits are energized, normal or reverse, or are decnergized the leads of the secondary winding of the trans iormer 7 have been i'narked plus (-t) and minus From this it will he noted that under absolute stop-an "tay conditions of the block K, as shown, the first section of this block is energized by reverse or caution current, that is, minus to plus from left to right, the second section is energized by normal. or clear current, that is, plus to minus and the third section of this block has its simplex circuit file-energized. Also, that when the lever 2'? is depressed to its abnormal position the simplex circuit of the block l; is the same as that of the block H or l of block al territory; that is, is energized plus to minus under clear and is energized minus to plus under caution tratlic conditions.

in the block H has been illustrated a typical railu'a j ehicle such as an engine and tender unit by wheels and axles l7 and 1.8. in tree t ot the first axle 17 ot the railway vehicle and directly over each track rail are disposed car-carried elements comprising cores l9 having coils 20 contained thereon. The cores 19 preferably are constituted of laminated iron of high magnetic quality tern'iinating in enlarged pole pieces. The coils 20 are connected in series so that voltages induced therein due to currents flowing in opposite directions in the two track rails are cumulative and have bridged across leads leading therefrom a condenser 21 ot the proper capacity to resonate the coils 20 for the frequency of the railway signaling current, so that the potential across this condenser 21 is a maximum. These leads are connected to the input side a track phase amplit 1; device All which includes suitable amp ifying tubes of the vacuum t -Jpe, sources of energy, and tuning devices, and whicn has its output leads con nected to the winding of a main relay h ll-l.

Similarly, cores 23 located in the rear of the lasttc-nder axle l8 l'iave their coils 24- connected in series so that voltages induced herein due to currents flowing in the same direction in the two track rails in multiple are cumulative, the leads leading from these coils being similarly resonated by a condenser 25, and through a line phase amplifying device AL these coils are adapted to supply a current to the other phase winding of the main reh y R.

The main relay MR is preferably one of the induction type which will assume its normal position when the raiiway vehicle moves in a clear block, in which tracltway and line phase currents are flowing which have a nor mal phase relation preferabiy misplaced suh stantially 9O electrical deg 'ecs; and obviously assumes the reversed position if the phase relation of one of these tracliway circuits is reversed and assumes the tie-energized position if one or both of these tracliway circuits are cut off.

The present invention has been shown in a system which contemplates a gradual reduction in the permissive speed of the train as it passes through a caution block by the well known cam-and-governor arrangement, in which a permissive speet cam is driven in accordance with the progress of the train through a caution block. Since this cam-andgovernor speed control mechanism by itself does not constitute any part of the pr sent invention this mechanism wiil be briefly de scribed, attention being directed to the application of V. K. Howe, Ser. No. 88,132 for a detailed description of such apparatus.

Referring to Fig. 2 this cam-and-governor mechanism diagrammatically illustrated is similar in many respects to that shown in the prior application to Howe Ser. 746,578 referred to. The shaft is driven from the wheels of the vehi cie in any suitabie manner and has a speed responsive device or centrifuge O of the well known centrifugal type mounted thereon. It is obvious from the drawings that the grooved collar 31 of the speet responsive device O moves downwardly as the speed of the train increase Adjm cent the shaft 30 and preferably at right angles thereto is a speed shaft 82 which has a bifurcated arm 33 pinned thereto of which suitable pins extending inwardly from the bifurcated end of this arm engage the groove in the conar 31, so that the shaft 32 is rocked to a position depending on thespeed of the train. On this speed shaft 32 is secured a sector 34 which is adapted to close contacts 35 when the speed of the train is below 15 miles per hour, as indicated by the legend in Fig. 3.

On the shaft 30 is also suitably secured a worm 36 which is in continuous meshed engagen'icnt with a worm wheel 87 secured to the shaftwhich shaft has a pinion 3ipinned thereon. The pinion 39 continuously meshes with the gear a0 pivotaily SUPPOliGfl on a journal 41. This journal 41 also pivotally supports the bifurcated end of an arm 42 which arm straddles the gear and has a pinion 43 journaled therein which is in con tinued mesh relation with the gear 40. This arm i2 urged upwardly by a spring So as to tend to place the pinion 43 into meshed relation with the mutilated gear L5. Under normal ciear trafiic conditions, however, this arm &2 is held in its lower position, as shown, by a cam starter magnet HOS.

The mutilated gear 4-5 is fastened to the high cam shaft i6, this shaft being held in its normal position by a spring 49 engaging the free end of the arm secured to this snaft 16. On the shaft 46 is contained a dis tance cam 4'7, which is adapted to operate co tacts as at a point depcndii'lg on the distance the train has traveled since the cam starter magnet HOS was tic-energized as more clearly pointed out hereinafter.

To the speed shaft 32 is suitably secured an arm 51 to the free end of which is pivotally connected floating lever 52, which lever has its free end bifurcated and provided with a roller 53 engaging the surface of a permissive speed am 50.. Obviously, since the arm 51 responds to the speed of the train and the cam 50 is shaped to move the roller 53, to set up permissive speed limits as the train proceeds with the cam starter magnet HOS deenergized, all that is necessary to open contacts when the actual speed of the train is too high as compared with the permissive speed is to cause lese contacts to respond to the movement of an intermediate point on the floating lever 52. In the particular arrangement shown a sector 5% pivotally supported by a journal 54 is provided, which sector has an eccentricaliy located pin 56 connected to an intermediate point of the floating lever by a link 57., so that this sector is rocked toward the right as the speed increases and also as the train progresses, so that the speed must be reduced as the train progresses through the block. This sector 5; is biased in a counter clockwise direction by a spring 58 so to hold the roller 53 against the cam 50. This sector 5% permits opening of the outwardly biased contacts 59 when the speed of the train is excessive. In a similar manner the iow cam shaft 46* for operating distance contacts only is provided. which shaft is turned in accordance with the progress of the train when the low cam starter magnet LOS is tie-energized, and since various parts of these devices are the same like reference characters with distinctive exponents a have have been applied to such parts of the low cam. shaft mechanism.

Referring now to Fig. 3 of the drawings, there has been shown in addition to the apparatus already referred to mechanism including an acknowledging relay A0]; R, a penalty relay PR. and an electro-pneumatic valve EPV. The two reiays ust mentioned may be of any suitable type, but are preferably conpneumatically op rated brake control device,

which device is adapted to vent the brake pipe to a predetermined extent in a manner so that the engineer cannot recharge the same, or is adapted to control a brake valve actuator for operating the usual cngineers brake valve to the service position in a manner so that the engineer cannot prevent such automatic operation of the brake valve.

Fig. 8 shows the electrical connections between the various devices of the car apparatus; and in this circuit plan, various conventions have been adopted to simplify the illustration and facilitate explanation. The vari ous contact fingers of the various relays are shown directly under the conventional illustration of the relay controlling them and are connected by dot and dash lines. Each distance shaft is similarly illustrated by a dot and dash line leading to the cam-starter magnet governing the same.

In order to facilitate the description of the various circuit changes that take place in the car-carried circuit arrangement shown in Fig. 3 it is considered advisable to trace the normally closed circuits first, after which the circuit changes may be considered as the train proceeds under various speed and trafiic con ditions.

The high cam starter magnet HCS is normally energized by the battery tl'irough a circuit including the contact 61 of the main relay MR when this relay is in its normal clear traiiic position, which circuit is readily traced in the drawings. Similarly the low cam starter magnet LCS is energized if the main relay MB is either in its normal or its reversed position through the following circuit :beginning at the bus bar 62 connected to one side of the battery 60, wire 63, contact 64- of the main relay MR, wires 65 and 66 depending on whether the relay MR assumes its normal or reversed postion, wire 6?, wind ing of the low cam starter magnet LCS, wire 68, push button PB, wire 69 to the other bus 70 connected to the other terminal of the battery 60. With the cam starter magnets HUS and LCS energized the distance shafts L6 and L6 assume the normal position as shown in F 2.

Under clear traiiic conditions as illustrated the penalty relay is energized by the following stick. circuit :beginning at the bus 62, wire 71, contacts 48 operated by the distance cam 17, wires 108, 72 and 78, distance contact 48 operated by the distance cam ll, wires Ti, 75, 7 6 and '57, front contact 78 of the penalty relay PR, wires 7 9 and 80, winding of the penalty relay PR, wire 81 to the other bus 70. It should be noted that the penalty relay PR is also energized under clear tratlic condi tions by a circuit including contact 82 of the main relay MR which is readily traced in the drawings and includes the greater part of the circuit just traced. The purpose for which this circuit has been provided is more readily pointed out hereinafter. T he device EPV is normally energized through the following circuit :Starting at the bus 62', wire 83, cam and governor contacts 59, wires 8%, and 85, distance contacts 86 operated by the distance cam 87, wires 88 and 89, front contact 90 of the penalty relay PR, wire 91, winding of the EPV, wire 92 to the bus 70.

Operation in block signal territory By looking at the circuit for the device EPV just traced it readily appears'that this device is (lo-energized if either the penalty relay PR is (lo-energized, the speed of the train is in excess of the speed set up by the permissive speed cam 50 as manifested by the opening of contacts 59, or if the contacts 86 of the cam 87 are open while the contacts 35 of the speed cam 34 are open due to the train speed being above 15 miles per hour.

In order to facilitate explanation, let us assume that the train in question equipped with the car apparatus shown in Fig. 3 in its normal condition is moving from left to right in the block H when the block I in advance thereof is a caution block, that is, with the block I unoccupied and the block J occupied by another train. So long as the train moves in a clear block only a certain maximum speed restriction is enforced which for the particular cam shown is 60 miles per hour as indicated by the curve 93 in Fig. 1 of the drawings. If the train exceeds this speed at any time an automatic brake application occurs, after which brakes may again be released by the engineer as soon as the speed is no longer excessive. As the train in question enters the block I the alternating current impressed on the winding 26 of the main relay MB- is reversed, because the line phase circuit in the block I has its polarity reversed by reason of dropping of contacts 10 and 15 of the track relay 3. This causes the main relay ME to swing its contacts 61, 6% and 82 to the left, thereby file-energizing the high cam starter magnet HCS and opening one of the circuits heretofore mentioned for energizing the penalty relay PR, namely, the circuit including the contact 82 of the relay MR, this relay PR- howe ver still being maintained energized through the other cireuitwtraced. lVith the high cam starter magnet HUS deenergized the high cam shaft 46 is gradually rotated, thereby decreasing the permissive speed of the train gradually as indicated by the curve 93 in Fig. 1 of the drawings. After a short distance of movement in the caution block the distance cam 94 closes contacts 95, as indicated by the solid portion of the line 95 in Fig. 1 of the drawings thereby closing a circuit which sounds the acknowledging signal A01: S by the energization ot the following circuit :beginning at the bus 02, wires 96 and 97, acknowle lging signal Ac]: S, wire 98, back contact 99 of the acknowledging relay A070 R, wires 100 and 101, contacts 5 operated by the distance cam 94, wires 102' and 103 to the other bus 70. The sounding of this acknowledging signal informs the engineer that he must perform an acknowledging act to show his Vigilance and in turn avoid an automatic brake application. If the engineer now presses the acknowledging push button PB a pick-up circuit for the acknowl edging relay Ae ie R is completed, which may be traced as follows:beginning at the bus 62, wires 90 and 10%, winding of the acknowledging relay A070 R, wires 105 and 106, push button PB, wire 69 to the other bus 70. It should be noted that with this acknowledgrela' A015 R energized, the circuit for energizing the acknowledging signal Ack S is broken. lVith this relay Ac/e R once picked up a stick circuit for this relay is completed as follows :-beginning at the bus 62, wires 98 and 101, winding of the acl-tnowledging relay Ada R, wires 105 and 107, front contact 99 of the relay Ada, wires 100, and 101, distance contact 95, wires 102 and 103 to the other bus 70.

Aft r the train has proceeded a little further the distance contacts 18 operated by the cam 17 are opened for a short distance of travel as indicated by the interrupted portion of the line 418 in Fig. 1 of the drawings. The opening of contacts 4:8 breaks the stick circuit for the penalty relay PR heretofore traced which includes these contacts 18, but since the engineer has manifested his Vigilance by depressing the push button PB and sticking up the acknowledging relay Ada R, an auxiliary stick circuit for the penalty relay PR is completed, which may be traced as follows :beginning at the bus 62, wire 71, contacts eh operated by the distance cam 17, wires 108 and 109. front contact 110 of the acknowledging relay Ads E, wires 111 and 112 and 77, front contact 78 of the penalty relay PR, wires 79 and 80. winding of this rela PR, wire 81 to the other bus '70.

After another short distan e of travel of the train the contacts 18 are closed and the contacts 95 are opened. The opening of con tacts caus s dropping of the acknowledging relay Ac]; R so as to again place it in its normal condition. As the train proceeds through the block I the engineer is obviously required to reduced his speed as indicated by the curve 93 to avoid an automatic brake application by opening of the permissive speed contact 59.

Near the end of the block I the distance shaft 16 will have reached its ultimate position wherein the pinion 43 engages the mutilated portion of the mutilated gear 45, after which the permissive speed is constant as iudicated by the horizontal line 113 (see Fig. 1). Also us" before the high cam shaft d6 reaches its ultimate position the contacts 114 operated by the distance cam 115 are closed indicated by the solid portion of the line 11% in Fig. 1 of the drawings. The closing of these cont: is does not complete a circuit but permits another auxiliary acknowledging circuit to be completed as more clearly pointed out hereinafter.

As the train proceeds into the block J, which is assumed to be occupied by said another train, no track phase current can be detected in the elements located in front of the first axle of the train because this current is shunted away by said another train in advance. This causes the main relay MR to assume its de-ener ized position so as to (lo-ener ize the low cam starter magnet LCS. With tars cam starter magnet LCS de-energized the low cam is gradually rotated in acc rdance with the progress of the train and .fter a short distance of movement of the the contacts are closed, as indicated the line 95 in Fig. 1, thereby again sounding the acknowledging signal Ads S through a circuit which is obvious from the drawings. The sounding of the acknowledging signal A070 S advises the engineer that he must dopress the push button PB to manifest his vigilance and that he is now entering an occupied block. Depression of the push button PB again picks up the acknowledging relay Act: which relay after once piared up is stuck up through the same stick circuit heretofore traced except that the present circuit includes contacts 95 and not 95.

Upon a slight further movement of the train in the occupied block the contacts 48* are opened as indicated by the horizontal line 1-8 (see Fig. 1) which interrupts the stick circuit for the penalty relay PR heretofore traced. The penalty relay is, however, not (lo-energized because it is now energized through tne following circuit :beginning atthe bus 62, wire 118, contacts 114 operated by the distance cam 115, wire 119, front contact 120 of the penalty relay PR, wires 121, 112 and 77, front contact 78 of the penalty relay PR, wires 79 and 80, winding of the penalty relay PR, wire 81 to the bus 70. In other words, the engineer has avoided de-energization of the penalty relay PR by depressing the push button PB in response to the acknowledging signal Aclc S. At about the same time that contacts 48 open the contact 86 is permitted by the cam shaft 46* to also open, as indicated by the line 86 in Fig. 1 of the drawings. With the contacts 86 open the device EPV relies for its energizing current upon the continuity of the circuit through speed contacts 35 which are only closed if the speed of the train is less than say, 15 miles per hour.

At first hand it would appear that the con tacts 35 and 86 are unnecessary, because the contacts 59 are already open if the speed of the train is over 15 miles per hour under the assumed conditions. There are however conditions where this is not true and these contacts 35 and 86 are essential. For instance, assume the train to be moving at a. very slow speed near the end of a block and a switch is opened in the block next in advance; under this condition the high cam would not yet have been run d wn when the train reaches the end of the block and under this condition the contacts 35 would set up the restricted speed limit.

It may be stated at this time that contact 82 of the main relay MR has principally been provided to prevent the requirement of acknowledgment when either the high or the low cam shaft are restored to their normal position, during which time the contacts 48 or 4:8, as the case may be, are open; and it will be noted that these contacts are shunted by the contact 82 during the restoration of these cam shaft's, so the penalty relay is not dropped. For instance, if traffic conditions change from danger to caution (both the high cam l7 and the low cam 47 in the run-down position) movement of the contact 82 from its neutral to its left-hand position closes the following circuit for the penalty relay PR beginning at the battery 60, bus wire 62, contact 82 of the main relay MB in its left-hand position, wire 73, contacts 48 of the high distant cam ll, wires 74;, 75, 76, and 77, stick contact 78, wires 79 and 80, windin of the pen alty relay PR, wires 81 and back to battery 60. Momentary opening of contacts 48" due to reenergization of the cam starter magnets LCS will not effect deenergization of the relay PR by reason of the presence of the auxiliary circuit just traced. Also, change in traiiic conditions from danger or caution to clear will not permit deenergization of the penalty relay PR even though contacts 48 are momentarily opened because the following auxiliary circuit is first closed :beginning at the battery 60, wire 62, contact 82 of relay MR assuming the right-hand position, wires 76 and 77, stick contact 78 of the penalty relay PR, wires 79 and 80, winding of the penalty relay PR, wires 81 and 70 back to battery 60. When either of these cams is restored to its normal position the acknowledging signal Ac /c S is momentarily sounded; since this momentary sounding of the signal can readily be distinguished from the sound ing when acknowledgment is required it may be used to inform the engineer that a favorable change in traffic conditions has taken place. The difference in the time during which this signal sounds when the cams are run down and restored respectively, is due to the fact that these cams are driven slowly from their normal position and are almost instantly restored by the spring 47 or 47 to the normal position. It should be noted that the push button PB is protected against misuse, that is, it cannot be permanently tied down, for by so doing the cam starter magnet LCS is tie-energized and the minimum speed limit of 15 miles per hour is immediately thereafter set up and continues so long as this push button is tied down.

From the above it appears that the engineer is required iTOlnZlliB an acknowledging act when achange of traffic conditions from clear to caution takes place, and also when a change of traftic conditions from caution to danger takesplace.

Operation at the approach to a st0p-cmcZ- sf'ag S';:II ((Z.LOiI us now consider the movement of a train during its approach to a stop-and-stay signal. Let us assume that a train equipped with the car-carried apparatus shown in Figure 3 enters the block K when a conflicting route is set up that is, the lever 27 is in normal position and the tower man cannot change this lever from its normal position. As the train enters the block K, consequently the engineer is required to acknowledge this change in traffic conditions and thereafter is required to restrict his speed in accordance with the permissive speed limit set up by the cam 50, as shown by the curv 93 in Fig. 1, so that the train has practically reached its minimum speed of 15 miles per hour when it reaches the balancing resistance 28. As heretofore mentioned, the section between balancing resistances 28 and 29 is provided with simplex current of normal polarity so that the relay MR- is again energized to its normal position for a short distance 7a of movement as indicated in the block K. This restores the high cam to its normal position, and as the train proceeds in the face of the absolute stop-and-stay signal ZA at danger, and passes beyond the balancing re sistance 29, a sudden change from clear to danger takes place because there is not simplex circuit current present between the balancing resistances 29 and 12 so that, the relay MR- changes from its normal to its deenergized position abruptly. This change of the main relay MR causes both the high cam shaft 46 and the low cam shaft l6 to be started at the same time, and after a short distance of movement the acknowledging signal A070 S is sounded for reasons heretofore given. Even if the engineer now presses the push button PB for reasons heretofore given, this will avail him nothin because the contacts 114 have notyet closed, so that,

the circuit for maintaining the penalty relay PR up including this contact 114 and the contact 120 of the acknowledging relay hell: is not complete at the time contacts 48 and 48 are open; and this relay PR is tie-energized and an automatic'brake application occurs. It is assumed that this brake application is suflicient warning to the engineer that he will not continue movement of his train after it has been brought to a stop.

The distance contact cams a7 and 1" are preferably so designed that the contacts 48 and a8 will have been reclosed before the train has been brought to a stop by the auto matic brake application just mentioned, and as soon as the train has been brought to a stop, a pick-up circuit for the penalty relay PR is completed which may be traced as follows z-beginning at the positive bus 62, wire 71, contacts 48 and 48, wire 7%, contacts which are only closed when the train is substantially at a stop, wires 123 and 80, winding of the penalty relay PR, wire 81 to the negative bus 70. The completion of this circuit obviously causes the penalty relay to assume its attracted position after which the stick circuit is completed and the penalty relay PR is again stuck up, so that the engineer may proceed if he desires to do so. The engineer will, of course, not proceed until the stop-and-stay signal ZA, assui'nes its clear position, which it will as soon as the tower man changes the lever 27 controlling this signal to its abnormal proceed position, it being assumed, of course, that traflic con-v ditions ahead are clear.

In order to assure that a change from clear to danger takes place at the approach of the train to an absolute stop-and-stay signal. the trackway circuits necessary to energize the relay HR to its clear position may be checked in any one of the well known ways, for instance, the wire leading to the midpoint of balancing resistance 29 may have a check relay therein which must be energized before a conflicting route can be set up, so that the possibility of a failure of proper operation of the absolute stop mechanism is very remote.

A train control system embodying the present invention has certain advantages over other train control systems of the continuous inductive type having absolute stop features incorporated therein heretofore proposed, in that, a failure of trackway energy by reason of transmission line trouble, or the like, merely effects a brake application regardless of speed after which the train may again proceed at the discretion of the engineer.

Although in the simplified train control system shown, no specific means has been shown for cutting out the automatic apparatus when the train enters the territory not equipped for train control, it is to be understood that suitable apparatus for this pur pose is in most instances necessary. If such means is to be employed in a system embodying the present invention it is proposed to employ the arrangement for picking up a non-control territory stick relay disclosed in the application of C. S. Bushnell, Ser. #723,048 filed June 28, 1924, to which reference may be made for this purpose.

Having thus shown and described one rather specific embodiment of the present invention and having shown it applied to a simple alternating current block signal system, it is desired to be understood that the specific apparatus illustrated has been selected for the purpose of disclosing means for carrying out the invention rather than for the purpose of illustrating the particular apparatus preferably employed in practice or the scope of the invention, and that various changes, modifications and additions may be made to adapt the invention to various other types of railway signaling systems or to systems in which no wayside signals are used and suitable cab signals controlled by the main relay MR are employed, all without do arting from the scope of the invention or the idea of means underlying the same.

What is claimed as new and desired to be secured by Letters Patent is 1. Gar-carried apparatus for automatic train control systems comprising, two delayed action devices one of which is initiated upon a change or" tratlic conditions from clear to caution and the other of which is initi ;ed upon a change from caution to danger, means for restricting the speed of the train differently when one or the other of these devices is initiated, and means for effecting an automatic brake application regardless of the speed of the train if both of said delayed action devices are initiated simultaneously.

2. Car-carried apparatus for automatic train control systems comprising, means for restricting the speed of the train to a given limit upon a change of traflic conditions from clear to caution, means for further restricting the speed of the train to a lower limit in response to a change in traiiic conditions from caution to danger, and means for stopping the train regardless of speed only upon an abrupt change of trafhc conditions from clear to danger.

3. Car-carried apparatus for automatic train control systems comprising, brake applying means for effecting a brake application it a change of tratlie conditions from clear to caution, from caution to danger or from clear to danger takes place, manually operable acknowledging means which if actuated when a change of trafiic conditions from clear to caution or from caution to danger takes place prevents a brake application by said brake applyin means but which is incapable of preventing a brake application it operated when a change of tratiic conditions from clear to danger takes place.

4. Car-carried apparatus for automatic t'ain control systems comprising, means for giving); a signal and for etlccting a bralre application it a change of tratlic conditions from clear to caution, from caution to danger or from clear to danger takes place, manually operable acknowledging; means which it actuated immediately atte said signal given prevents a brake application by said first mentioned means 113011 a change from clear to caution or caution to danger but which is incapable of preventing a l alto application if Opfiltlttl when a signal is given in response to a c u nge of traiiic conditions from clear to dancer.

5. In an automatic train control system; the combination of car-carried apparatus comprising, an electroresponsive device adapted to assume three different positions in response to clear, caution and danger tratlic conditions ahead respectively, means for restricting the speed of the train upon a change in traffic conditions from clear to cantion, another means for restricting the speed of? the train upon a chai'ige in tratlic conditions from caution to danger, and means for effecting a brake application regardless of train speed when a change in tratlic conditions from clear to danger takes place; and of trackway apparatus at the approach to a stop-and-stay signal tor causing said relay to change from clear to danger as the train approaches said stop-and-stay signal thereby stopping the train upon its approach to such signal regardless of the speed of the train at the time.

6. In an automatic train control system for railroads; the combination of car-carried apparatus including a slow acting device char ing in accordance witl the progress of the vehicle when active and initiated upon a change in tratlic conditions from clear to caution, another similar slow acting device initiated upon a change in traiiic conditions ahead from caution to danger, a manually op rable device, means for cheating an auto 'c bralqe application when either of said devices are initiated unless said man .ally operable device is operated and edective to automatically apply the brakes regardless of tie operation of said manually operable device when both of said slow acting devices are initiated simultaneously; and of tracl-:- way means at the approach to a stopand-sta signal for manifesting on the car tratiic conditions corresponding to a change from clear to danger the car approaches said signal, thereby effecting a brake application regardless 0i whether or not the engineer operates said manually operable device.

7. In an automatic train control system for railroads; the combination of car-carried apparatus including a slow acting'device changing in accordance with the progress of the vehicle and initiated upon a change in tratiic conditions from clear to caution, another similar slow acting device initiated upon a change in tratfic conditions ahead from caution to danger, a manually operable de ice, means for reflecting" an automatic brake application when the train traveled a predetermined distance after either of said devices are initiated unless said manually operable device is operated and effective to automatically apply the brakes regardless of the operation of said manually operable de ice when the train has traveled a pred termined distance after both of said slow acting devices are initiated simultaneously; and 0t trackway means located at the approach of a stop-and-stay si nal for manifesting on the car traiiic condi tions corresponding to a change from clear to danger when the car ap 'iroaches said signals, whereby an automatic brake application is ciiected regardless of whether or not the engineer operates said manually operable device after the train has traveled said predetermined distance with both of said slow acti Q devices initiated.

S. in an automatic train control system, tratlic controlled trackway means for transmitting influences corresponding to traiiic conditions to a moving vehicle, such influences changing trom clear to caution and from caution to danger in response to increasingly unfavorable tratiic conditions ahead, and changing from clear to danger at certain points along; the trackway where a stop is required, car-carried apparatus comprising means for restricting the speed of the train to a given limit upon a change of said influences from clear to caution, means for further restricting the speed of the train to a lower limit in response to a change of said influences from caution to danger, and means for stogping the train regardless of speed only upon a chan e of influences directly from clear to aautomatic train control system, traffic controlled track ray means for producing on a moving vehicle three oitierentsig nal impulses in a given scruieuce under certain t aclrway conditions, and for producing a diti erent sequence of impulses under other trackway conditions, car-carried means responsive to said impulses for producing a given degr e of control in response to said given sequence of impulses and responsive irrespective of manual control for producing a different degree of control in response to said different sequence of impulses.

10. In an automatic train control system, car-carried apparatus comprising means for restricting; the speed of the vehicle upon the reception of three distinctive signal impulses in a given sequence, and means for stopping the train. only upon the reception of two of said signal impulses in a different sequence.

11. In an automatic train control system, car-carried apparatus including means for giving a permissive stop control of the car upon reception of at least three distinctive signal impulses in a given sequence, and an absolute-stop control of the car upon reception of impulses in a different sequence.

12. In an automatic train control system, car-carried apparatus including means for giving a permissive stop control of the car upon each change of at least three received distinctive signal impulses in a consecutive order of less to more restrictive character.

and an absolute stop control of the car upon change of impulses in a non-consecutive order.

13. In an automatic train control system, traffic controlled trackway means for producing on a moving vehicle at least three different signal impulses in a given sequence, traflic controlled trackway means for producing a different sequence of impulses, and car-carried means responsive to said impulses for giving a permissive stop control in response to said given sequence of impulses and for giving an absolute stop control in response to said different sequence of impulses.

In testimony whereof I afiix my signature.

FRANK L. DODGSON.

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