US1601427A - Continuous inductive train control - Google Patents

Description

Sept. 2 8 1926.

C. S. BUSHNELL CONTINUOUS INDUOTIVE TRAIN CONTROL 1924 2 sheets-'sheet 1 Filed Sept. 20,

Sept. 28 1926. A C. S. BUSHNELL CONTINUOUS INDUCTVE TRAIN CONTROL Filed Sept. 2O 4 1924 Sheets-Sheet 2 F\G.2. Y @PB 57 e8 S9 -,L C B 100 3?- 3 108 55 r mi? Patented Sept. 28, 1926.

UNITED STATES PATENT orricE.

CHARLES S. BUSHNELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAIL- WAY SIGNAL COMPANY, 0F ROCHESTER, NEW YORK.

CONTINUOUS INDUCTIVE TRAIN CONTROL.

Application filed September 20, 1924. Serial N'o. 738,878.

This invention relates to automatic train control systems for railways, and more par-v ticularly to the provision of suitable automatic means which requires the engineer to take appropriate action, conveniently termed acknowledgment, at or near each stop signal, otherwise an automatic application of'the brakes occurs and the train is brought to a stop',.or other suitable penalty is inflicted.

More specifically, in accordance with the Vpresent invention, it is proposed to require the engineer to perform an acknowledging act at successive points or intervals of distance in the travel of the train while running under a stop signal through a danger or occupied block. lect an interval-of distance for such recurrent acknowledgment as will cause the acknowledgment to take place at the first` stop signal encountered by'a Atrain and at, or`

closely adjacent to the succeeding stop sig'- nals. In the form of the invention illustrated, acknowledgment of each caution signal is required, in addition to the ac-V knowledgment of successive stop signals; but obviously the acknowledgment of the stop signals may be used alone, ify desired.

IVith the idea of facilitating traffic, and for other reasons, it is proposed in this invention to eliminate the stopping of the train or other penalty for failure to acknowledge if traliic conditions clear` up in the meantime.

In order to protect the acknowledgingV device from abuse, according to this invention, the engineer must restore this device to its normal or inactive condition in order to consummate the acknowledging act, with the result that he cannot defeat the purposes of the device by permanently holding or fastening it in the active acknowledging position.

Other objects, Vpurposes and characteristic features of this invention will appear as the description thereof progresses.

In describing the invention in detail reference will be made to the accompanying drawings in which F ig. l illustrates an especially simple railway signaling system, upon which the trackway apparatus for a simple form 'of automatic train control system embodying the present invention has been superimposed; and

It is proposed to se-` 'assumed to be equipped the same,

Fig. Q'illustrates conventionally and in a diagrammatic and perspective manner one form of car-carried apparatus embodying the present invention.

Although the present invention is applicable to various types of train control systems, such as intermittent systems of various kinds and continuous inductive systems of the three-position type, it has been shown applied to asimple form of two-position continuous inductive train control system so as to simplify the illustration and description thereof. Y

Referring to Fig. l, the reference characters l designate the usual track rails which vare vdivided by insulating joints 2 into blocks in the usual way, the block I and the adjacent ends of the blocks H and J only being shown. Since the variousblocks are like parts of each block are designated by like reference characters having distinctive exponents. Using the reference numbers for the "block I, each block has connected across its rails at theexit endthereof the usual track battery 3 connected in series with the usual limiting resistance 4i; and the entrance end of each block has bridged across the rails thereof the usual track relay 5, which is in this case a direct current relay. Although the present train control system may be used either with or without wayside signals of any suitable type, signals Z of the semaphore type have been illustrated for convenience, without showing their well known operating mechanism and control circuits.

In addition to the usual signaling apparatus thus far described. alternating current isgsuperimposed upon the direct current in the track circuit by the transformer 6, having its secondary winding connected in selries with the battery 3, and having its primary winding connected to the transmission line 7 through a front contact S1 ofthe track relay 51 of the block J next in advance.

On the railway vehicle or locomotive, which has been conventionally illustrated by wheels and axles l0 and 1l, is a main control relay MR, which' is adapted to respond to the presence and absence, respectively, of alternating' current fiowing in the track rails ahead of the vehicle. In the particular arrangement shown, this main relay MR is connected to the output side of an amplifying device A, which includes suitable am- Y Howe, Ser.

Ul l

I of Athe amplifier Y trated. lf the train is in a :speed responsive plifying tubes or audions, sources of energy, timing devices and the like. The input side A isl connected 'to the coils 12 and 13 on laminated car elements 14 and 15 which are disposed directly over the rails ahead of the train. 'These coils 12 and 13 are connected in series, so that voltages induced therein due Ato current liowingin one direction in onerail and in the other direction in the other rail are cumulative and these coilsare preferably timed to resonance for the particular frequency user, by bridging aci'oss the leads thereof the condenser -16 of the'proper capacity. Although the 'coils 12 and 13 have been shown surrounding cores of laminated magnetic material, these coresrnay be omitted inpractice, if

desired V,de ending somewhat on the t ae of v i 3 D amplifying device andthe frequency of the alternating current used.

Referring to Fig.l 1, it will be noted that the main relay MR assumes its energized position when the train is moving in a clear block, in whichj position it has been illluscaution block, the main relay MR assumes de-energized position, because no alternating current lis present in the track rails directly ahead of the train by reason of the fact that the track relay of the block neXt in advance, under the assumed caution condition, in the de-energized position, and the transformer 6 is disconnected from the transmission line 7. On the other hand, when the train in question follows another train in the same block, it is deprived of, alternating` current even if such current is applied to the exit end of the block, because such alternating current is shunted away from the following train in question by another said train ahead in the saine block. The response of this main relay hilt to changGS in traffic conditions ahead should be borne in mind in connection with the description 'of the car apparatus in Fig.2. Referring to Fig, 2 of the drawings, carcarried apparatus of the well known cam and governor type has been illustrated; and since the various elements of the speed control apparatus are well understood by those skilled vin theatrt and are described in considerable detail in the application of il?. l. No. 33,132 filed July 6, 1915, this apparatus will only be briefly described. 1n the arrangement shown, a centrifugal device or centrifuge C is supported on a shaft 2() driven from the `wheels ofthe vehiclein any suitable manne-r.

The grooved collar 21 of the centrifuge C moves downwardly as the speed of the vehicleincreases, so that'the speed shaft 22,

1 which `is operatively connected to this collar V clockwise direction as lconnected. a floating paratus illustrated, the speed of the train is above the minimum speed enforced by this speed controhapparatus, whichV miniiiiuin speed is assumed to be 15 miles per hour. Fixed on the shaft 20, drive-n from the wheels of the vehicle, is a worin 24, which is in continuous meshed relation with a worin wheel 25 pinned to a shaft 26. A pinion 27, pinned to the shaft 26 is in `continuous ine-shed7 relation with gears 23aiid 29 which are pivotally supported on journals 30 Vand 31, respectively. 'y A bifurcated or forked arin 32 has its bifurcated end straddling the gear 28' and is pivotally secured on the journal 30, sorthat this arni may swing 'concentrically with the gear 28 about the journall 30. ln the bifurcation of this arm is pivotally journaled a pinion 33 in a manner so that it continuously meshes 'with thefgear ASv. This arm 32 is urged upwardly by a tension spring 34 but is normally heldin its lower position, against the tension of this spring, by the armature. 35 attracted by the speed control cam `starter magnet Similarly, a pinion 36 is carried iii-the bifurcated a'rin 37 held in its lower position by an acknowledging cani starter niagnet CSA, the arm 37 being urged upwardlydby a spring 33. Y Y

Directly above the pinion 33 and in alignincnttherewith, is'd'isposed a mutilated gear 40, which is pinned Atoadistance 'shaft 41, so as to turn this shaft in accordance with the progress of the train 4while the mutilated gear 40 is in rnesh with the pinion 33. To the distance shaft'41 are firmly secured for rotation therewith a? permissiie speed cam 42 and four 'distance cams 4,3, 44, 45 and 46. rlhese distance cams, through suitablerollers cooperating therewith, areradap't'ed to close contacts 47, 7 3, 48 and 51 respectively, during various angular positions of this distance cani shaft 41.

To the speed shaft 22 is secured a speed arm 17, to the free end of which is pivotally lever 1S, having a roller 19 at the free end thereof which rides against the cani surface of the cam 42. Ey observing the manner in which this floating lever 13 is supported, it is obvious that all that is necessary in order to operate suitable contacts in accordance with the speed 'of the train as con pared with the permissive speed set up rby cani 42, is 'to operate such contacts in accordance with the position'of an intermediate point on this floating lever 13. ln the particular arrangement shown, this has been accomplished by providing a sector 52, pivotally supported on a journal and having an eccentrically located pin 54 thereon, which is connected to an intermediate point on the floating lever '.13 by a link 83. This sector 52 'is biased in a lcounter-clockwise direction by the spring 39 and is shaped so as to cause contacts 33 to open when the actual speed of the train is higher than the permissive speed setup by the permissivel .adaptec'hthrough the medium of rollers engaging the surface of these cams to opera-te contacts 6l, 62, 63 and 64, respectively, at various angular positions of the acknowledging shaft 55.

Since` the present invention does not relate to any particulartype of apparatus for applying the brakes cf the usual air brake system, no specific type of device for carrying out this `function has been illustrated. An electro-pneumatic valve EPV has, however, been shown, which may be used to actuate the usual engineers brake valve in a manner so that the engineer may notr prevent its operation, or which maybe used to operate a suitable application valve, which vents the brake pipe and cutsthe main reservoir pressure loft the'engineers brake valve so that he cannot recharge the brake pipe While this application valve is in its active position.

rIhe acknowledging device or contractor is shown as a simple button PB, resilient or Yspring returned, and having normally open and normally closed contacts. This push button PB is located at some convenient point in the cab and in easy reach of the engineer, and is enclosed in ar suitable locked or sealed casing, with only an operating member projecting', so that the engineer cannot interfere with the electrical connections.

Operation.

Afrom the terminal B of a suitable source of energy, which has its other terminal connected to a common return wire C, which circuit includes a front contact ofthe main con-v trol relay MR. IVith the distance shaft 4l in its normal position by reason of the energization of the cam starter magnet CSS,

f the cam starter magnet for the acknowledging shaft 55 is energized through a'circuit as follows Beginning at the terminal Bof a suitable source of energy, wire 66,v contacts 47 operated by the distance cam 43, Wire 67, contacts 6l operated by the distance cam 57, wire G8, winding of the cam starter mag.- net CSA, wire 69 back to common return wire C to the other terminal of said source.

The penalty relay PR is .normally en.- ergized by the following circuit beginning at the terminal B, wire-72, contacts 73 andV 49 of the distance cam 44, wires74 and 75, conta-cts 5l of the distance cam 46, wires 76 and 77, front contact 78 of the penalty relay PR, wires 79 and 80, winding of the penalty relay PR, wire Sl, back to the common return wire C. There are several other circuits by which the penalty relay PR is normally energized, but these can more advantageously be considered hereinafter.

Under normal conditions of the apparatus' A when the train is moving at an intermediate speed, as heretofore assumed,the electropneumatic brake control device EPV is energized through the following circuit z-beginning at the terminal B, wire 82, cam and governor contacts 83, wire 84, front contact 85V of the penalty relay PR, wire 8G, winding of the .device EPV, wire 87, back to common return wire C. From this circuit, it will be noted that the device EPV is. cle-energized if either the governor-cam contacts 83 or tne front contact 85 of the penalty relay PR are opened.

Maximum speed limit-While the train is traveling in a clear block, the brakes are automatically applied if a predetermined maximum speed is exceeded. Referring to Fig. 2, it will be evident that, after a certain speed has been reached, the lower end of the floating lever 17 will have been moved far enough vto the left, with the cam 42 in the normal initial position shown, to canse opening of the contacts 83, thereby de-energizing the brake controlling valve EPV. As soon as the speed of the train is brought down by such automatic brake application below the maximum normal running speer., the contacts 83 close again, the valve EPV is again energized, and the engineer may release the brakes. Consequently, there isY no particular penalty for exceeding the maximum speed limit under clear traflic conditions.

Uri-ation Hoda-Let us now consider the operation of the car-carried apparatus, as the. train moves from the block H which is assumed to be clear toward the right when the block' J next in advance is occupied, that is, when the block I is a caution block. As the train moves into the vblock I, the main relay MR assumes its cle-energized position, the cam starter magnet CSS is cle-energized, and the pinion 38 comes .into meshed relation with the mutilated gear 40, turning the distance shaft 4i in one direction or the other depending on whether the train is moving pilot entender first. After a short distanceiof movement lil() ffii) 'of the train, -tal line 4S .-in Fig.

to common return wire C.

as indicated by the horizon- 1 ofthe drawings, the contacts 48 operated by the distance cam u-close. Thefclosure of these contacts causes the acknowledging signal Ack S to sound, giving the-engineer a warning that he must now manifest `his vigilance by operating the acknowledging' push button PB in order to ayoidan automatic brake application. The circuit for sounding` this signal `may be Atraced as Ylkllows1-beginning at the terminal '15, wire 90, `contacts 48 operated by distance cani 45, wires 91 .and 92, back contact 93 of the acknowledging relay Ack R, wire 94, acknowlec ging signal. Ack S, wire 95 lv ck to common return wire C.

fldroceeding on the assumption that the engineer is vigilant `andresponds promptly by depressing the push button BB, la pickv.up circuit for the acknowledging relay Ack R- is completed as followsz-beginning at ithe .terminal B, wire-9G, acknowledging push button flp, wires 97 and 98, winding of the acknowledging relayrAck R, wire 99, back With this acknowledging relay Ack R once picked up, a stick circuit for this device is completed which may be traced ras 'follows z-beginnin at the terminal B, wire 90, contacts 48 of the distance cam .45,wires 91 and. 92, contact 93 of the acknowledging relay Ack R in its 'raised position, wires 100, :101 and 98, winding of the acknowledging rrelay rick R, wire 99, back to common ret-urn wireiC. At should be noted that Vthe acknowledging signal is discontinued vas .soon as the acknowledging relay Ack R is energized, be cause the acknowledging signal circuit includes the back vcontact ofarmature 93 of `this relay.

i/rftera further short distance of travel, as indicated by a solid lportion of horizontal lines 49,:and 50 in VFig'. `1 compared with the horizontal line 48, the .contacts 49 yopen and the contacts 50' close. These contacts are operated by -the distance cani 44 and used for the purpose of makingl the requirement rof acknowledgment by the acknowledging shaft hereinafter to be explained effective or ineffective depending on the position of' the distance shaft 41. lliththe contacts 49 open, the main stick circuit for thevpen- .alty relay PR heretofore traced is no longer intact, but another stick circuit which may vbetracedvas follows maintainsithe penalty relay PR energizedzbeginning at the. terminal B,.wire 104, contacts 63, .operated by the acknowledging -cam 59, wires and .7 5, contacts 51 operated by thedist-ance cam 46, `wires 7.and 77, front contact 78 of the penalty relayPR, wires 79and 80, winding of the ypenalty relay PR, wire 81 `back to common returnv wire fetter a further short distance of travel,

which 'may bey observed. by looking at the fact that .the engineer :so as to energize't-he y Ack R, as has been assumed, he .has comknowledging relay fick R,

.neo-1,427

vhorizontal-linesin Eig. 1, the contacts 51 open for a short distance of travel, as indicated by the dotted portion Aof the line 51 (see Fig. 1). Opening of contacts 51 inter rupts the stick circuit Jfor the penalty relay PB heretofore traced, but by reason of the l was vigilant and operated the acknowledging push button FB, acknowledging relay pleted another stick circuit for the penalty relay PR which may be traced as follows tbeginning at the. terminal 13, wire 96,7push button contact PB, wire 198, front contact v109 of the acknowledging relay Ack flhwires 110 Vand 77, front Contact 78 of the penalty relay PR, wires Z9 and 80, ywinding ofthe -penalty relay 13R, wire S1 back to the common return wire C. 1t should be notedthat this penalty relay stick contact of the push button PB closed in its normal position, so that the engineer is notI only required to operate the push button, but is required to return it to 'normal sofas to consummate the acknowledging act. 'Had the acknowledging relay notbeen stuck up or the acknowledging push button been retnrnedfto normal, the device EPV would rhave been cle-energized,because of dropping of the Contact 85 of the penalty relay PR. The contacts o1 are opened for a'shortdistance of travel only (see the Vhorizontal line 51), and a short distance of travel after here contacts 51 are again closed, the contacts 48 again open. The opening of contacts 48 breaks the stick circuit :for ltheacthereby causing its normal dethis relay [to again assume venergized position.

As thetrain now proceedsthrough the caution b-lock I, the block J neit in vadvance remaining occupied, the permissive speed set up by the permissive Vspeed cam 4Q gradually decreases, thereby requiring the engineer to reducehis speed substantially as indicated bythecurye 106 (Fig. 1') to avoid an automatic brake,application'by opening of the cam-governor vcontacts 83. vWhen the train has progressed a distance in the block .to the Vpoint indicated by the vertical line 107, the distance contacts 47 open, thereby breaking'the circuit for the acknowledging cam starter magnet CSA, thus cruising' 'the acknowledging cam shaft `55 tobe rotated inl accordance with the progress of the train through the medium of .pinion-36.

After a short distance of travel with the cam startermagnet CSA dc-energized,'the contactsl open, thereby assuring that this cam starter magnet GSA is not again re-energized until the shaft 55 assumes its Ynormal position. The gear 56 is not provided with a mutilated portion, as is the gear 40s'o that the gear 56 continues to rotate so long as the, train mores and the nain startem agnet circuit includes the Y plete rotation of the acknowledging shaft' 55. rlhe following stick circuit maintains the acknowledging relay energized, if it is otherwise momentarilyV energized beginning at the terminal B of a battery, wire 125, contacts G4, wire 126, front contact 127 of the acknowledging relay, wires 128, 101 and 98, winding `of the acknowledging relay Ack R, wire 99 and back to the common return wire C. The purpose for which these contacts 64 were provided is more readily explained hereinafter.

The rotation of the acknowledging shaft does not change' the function of the permissive speed cam 42, this speed cam continuing to reduce the permissive speed, as indicated by the curve 106, until the permissive speed has been reduced to its ultimate miniin'um or low limit, assumed to be 15 miles per hour, as indicated by the horizontal line 111. Shortly after the train has been restricted to this minimum speed and when the acknowledging shaft 55 has rotated substantially a half revolution, this acknowledging shaft closes contacts l62 (see horizontal line in Fig. 1), thereby closing a circuit for the acknowledging signal J4ck S as follows :-beginning at the terminal B, wire 72, contacts 73 and 50 operatedby the distance cam 44, wire 112, contact 62 operated by the acknowledging cam 58, wires 113 and 92, back contact 93 of the acknowledging relay Ack R, Wire 94, winding of the acknowledging signal Ack S, wire 95 back to common return wire C. The sounding of this audible acknowledging signal Ack S advises the engineer that her must manifest his alertness; and if he does this by depressing the push button PB, the acknowledging relay will again be picked up and stuck up, and the acknowledging signal silenced in the same manner heretofore described.

Upon a further slight movement of theV train the contacts 63 are opened, as indi-- cated by the line 63 (see Fig. 1), and if the engineer had failed to operate the acknowledging device because he was incapacitated or did not attend to his duties for some other reason, opening of the contact 63 would have interrupted the auxiliary stick circuit for the penalty relay PR heretofore traced, and would have effected an automatic brake application, so as to reduce the speed of the train as indicated by the curve 114 and bring the train to a stop. Since, as has been assumed, the engineer has performed the required acknowledging act, the penalty relay stick circuit is held closed by contact 109 of the acknowledging relay. v

it should be borne in mind that the acknowledging relay is now stuck up through two stick circuits, one including front contact of armature 93 and the other including front contact of armature 127, and that this relay will not assume its Cle-energized position until both of these stick circuits are broken. Upon a further short distance of movement of the train, contacts 62 again open and break the stick circuit including the front contact 93. When the acknowledging' shaft has substantially completed one revolution, the contacts 64 again separate and the other stick circuit of the ac- Ack R assumes its Cle-energized position.

As the train continues to move in restricted territory, that is, so longr as the main relay MR is cle-energized, the acknowledging signal is repeatedly sounded, and acknowledgment is required for reasons just given each time the acknowledging shaft 55 completes a revolution after the acknowledgment ust considered.

If the train again moves in clear territoryand the main relay MR is 11e-energized, the resultant re-energization of the cam starter magnet CSS causes immediate return of distance shaft 41 to its normal position. This return to the distance cam 44 to normal causes the Contact 73 to again assume its normal position, as shown in the drawings,v

so that the operation of contacts 62 and 63 does not sound the acknowledging signal Ack S or require an acknowledgment by the engineer, even though 'these contacts are operated by the acknowledging shaft 55,

' possibly because this acknowledging shaft `has not yet reached its ultimate normal position. As soon as the acknowledging shaft 55 again reaches its normal position and closes contacts 61, the energizing circuit for the acknowledging cam starter magnet CSA is again completed, thus causing the pinion 36 and the gear 56 to be disengaged and leaving the acknowedging shaft 55 in its normal position.

If the engineer has failed to operate the acknowledging device at a point in the movement of the train when such operation is required and has for this "reason dropped the penalty relay PR, the device EPV is immediately cle-energized and remains cle-energized so long as danger trailic conditions eX- ist, and if traliic conditions in the meantime clear up and the main relay MR again assumes its energized position, the penalty relay PR is automatically picked up 'and maintained up by a circuit which may be knowledging relay is broken and this relay` tracedV as follows-beginning at the terminal B, wire 117, front contact 118 of the penalty relay PR, wires 119, 120 and SU, winding of the penalty relay PR, wire 81, back to common return wire C.

If the engineer fails to manifest his vigilance; for reasons just mentioned, and the penalty relay PR and the device EPV are cle-energized, and traffic conditions do not clear up until the train is brought to a stop, this penalty relay PR may be picked up as soon assthetrain is brought to a stop by reason of the speed contacts 121 which are closed when, and so long, as thespeed of the train is substantially zero. The circuit through which the penalty relay PR is picked up after' theI train has been brought to a stopdepends upon the speed at which. the train is traveling when this relay PR is de-ener gized. Assuiningthat the train is traveling at a: highy rate of speed and is entering a cautionr block when the engineer fails to acknowledge `and thusy permits the cle-energization ot the relay, PB, the motion of the train in being brought to a: stop is sufficient to close the contacts 5l before the actualstop is made. speed' contacts 121 are closed, the relay PR is picked up at once through the following circuit z-fronithe battery terminal B, wire 1041, contacts 63 of the cam 59', wires 105 and 75, contacts 51 of the cam 4G, wire T6, contacts 121, wires 120 and 80 and the winding of the relay PR through wire 81 to the battery terminal- C. lf it should occur because of' a very high. train speed at the time that acknowledgment was required that the contacts 63 are open when the train comes to a stop, the pickup circuit just traced is not completed, but the engineer may in this case re'-energize the penalty relay by operating the push` button PB and energizing the acknowledging relay rick R. Once energized", the acknowledging relay is stuck up through a circuit including` its front contact 127 and the contacts 611 of the cam 30, which stick circuit has been traced, and when the push button PB is released by the engineer and returned to its normal position as shown, a pick-up circuit for the penalty relay is completed, which circuit may be traced as follows :-from the battery terminal B, wire 96, push button PB, wire 10S, front contact 109 of the acknowledging relay irck R, wire 110, Zero speed contacts 121,

wires 120 and 80, Winding of the relay PR and wire 81 to the battery terminal C. 1n

the engineer may re-energizethe penalty relay PR if he has failed to acknowledge at repeat-ed distance intervals while traveling under unfavorable traffic conditions, the stick circuit for the relay having been broken at the contacts 63 of the cam 59 andthese contacts having remained open after the train has come to a stop, due

the 5211119 111 tllllll ln this case, after the Zei-o Leones? to the slow speed ofthe train. lf theV train is moving very slowly as it first encounters unfavorable traiiic conditions, and the main' relay MR is first cle-energized, the train may be brought to a stop upon the failure of the 'engineer' to acknowledge, while the contacts 51 of the cam e6 are still open. 1n this case, the engineer may re-energize the relay PR to permit a reease of the brakes by depressing tlie push button PB as before to' energize the relay Ack It, which relay is now stuck up through its front ContactV 93 and the contacts 48 ofthe cam Ll5 through a circuit which has been traced above. The return of the push button PB to its normal position closes a pick-up circuit to the relay PR through the contacts 109 and 121 as e2;- plained above. ln actua-l practice, if the engineer has permitted the relay PR to become cle-energized. by reason of his failure to acknowledge at the proper time, and the train is brought to a stop, V'f the relay PR'i's not at once automatically energized to permit a release of the brakes the engineer depresses the push button PB and thus obtains a release from the penalty stop.-

From the above it is evident that ifv the engineer' fails to make an acknowledgingact andtratlic conditions immediately thereafter clear up the penalty consists only iii requiring him to retard the train by reason of an automatic brake application until traffic conditions do clear up, and if traflic conditions do not immediately thereafter clear up he is penalized to a greater extent, in that he is required to bring the train to a stop before liercan again proceed.

lt should be noted that it" the stick circuit for the acknowledging relayincluding contacts 64 and 127 had'noty been provided, repeated acknowledgment would have been required if the engineer made switching movements back and forth at about a.v point where acknowledgment is required. By the provision of this additional stick circuit the acknowledging relay if once picked up is held up for ak half revolution of the shaft 55 in either direction from the acknowlec 'ging point and the distance the train would have to travel to drop this relay by opening contacts 6e is greater than what would occur in ordinary switching movements. ln this connection it should further be noted that the provision of this contact Llpermits the engineer to nialie the acknowledging act before it is really required, and if he does so, the acknowledging signal will not be sounded at the regular acknowledging point.

lt should be noted that all of the distance cams, that is, those on the` acknowledging shaftas well as those lon the distance 'shaft 1-1 are symmetrical as far as the 'upper and lower halves are concerned.

rl`his construction is used so that the permissive speed perforinance as well as the requirement for acknowledgment is the same Whether the engine travels l"pilot or tender first. ln practice additional influence receiving elements are placed in the rear of the last tender axle which elements are automatically or manually substituted for the elements illustrated when the engine and tender unit travels tender first instead of pilot first as illustrated.

Reviewing the characteristic features of the operation of the embodiment of the invention shown, it will be observed that the enforcement of acknowledgment for the first stop signal is the result of starting the acknowledging` shaft 55, resulting in the opening of the contacts 63. If the engineer fails to acknowledge, the brakes are applied automatically upon the opening of the contacts 63; and in order that the train may at all times be g-overned on the side of safety, the system is organized lsuch that these conacts 63 open at a point near the exit end of the block which is braking distance for the minimum speed of the system from the physical exit end of the block. As indicated in Fig. 1, the contacts 63 open at a point where, if the brakes are applied on account of the failure of the engineer to acknowledge, the train will be brought to' a stop at or before reachinon the. end of the block as shown b f the braking distance curve 114.

Since the point in the block at which the contact G3 open depends upon a point in the block where the contacts 47 open to start the shaft 55, and this point in turn depends on where the car relay MR is cle-energized to start the shaft 41, it will be evident that in practice the trackway circuits for the several blocks on the railroad should be organized, by following out well known eXpedients, such as cnt-sections and the like, so that the car relay mit is cle-energized at a fixed distance from the exitend of each block, providing of course the next block in advance is occupied. If, as sometimes happens in practice, the proper point for cle-energizingthe car relay MR does not come at the en- Arance to cach particular block, the point for acknowledgment of the caution signal may be some distance either in the rear or in the advance of the wayside caution signal itself. For this reason, it is desirable to provide the acknowledging signal Ack S, preferably as an audible signal, to `guide the engineer in making his acknowledgments. Also, since the caution acknowledgment may not be at the wayside signal itself, such acknowledgment does not serve satisfactorily to enforce vigilance on the part of the engineer in observing thc wayside signals; Vand aside from showing that the engineer is alive and not incapacitated, the acknowledgment for the caution signal required by the system shown and described may be omitted.

rlhe gear ratio driving the shaft is preferably selected so as to cause one rotation of this shaft during a distance of travel corresponding approximately to the normal block length, so that after passing the first stop signal, the acknowledgment enforced by the next revolution of the shaft 55 will take place near the second stop signal. Such proportioning, however,lis optional; and if l desired, the shaft 55 may make one revoluthe ideaof the present invention, it is de-V sired to be understood that this has been done for illustrative purposes rather than for the purpose of showing the exact mechanism preferably employed in practice or the range and scope of the present invention, for ins ance. the same general arrangement may be applied to either intermittent or'threeposition continuous inductive type train control systems by making suitable additions and changes to adapt the invention to such systems without departing from the scope of the. invention or the idea of means underlying the same.

lVhat is claimed as new and desired to be secured by Letters Patent is y 1. In an automatic train control system, the combination of a speed restricting device governed in accordance with traflic conditions ahead and initiated if traffic conditions -ahead are dangerous so as to gradually reduce the permissive speed at which the vehicle may travel Without incurring an automatic brake application, normally energized means cle-energized so long as traflic conditions ahead are dangerous for applying the brakes regardless of the speed at which the train is traveling and effective a predetermined distance after said speed restricting device has been initiated, and means for preventing saidA last mentioned means from applying the brakes effective if actuated at repeated distance intervals.y

2. In an automatic 'train control system, the combination ofa brake setting appliance, normally energized means maintained deenergized under unfavorable traiiic conditions and acting when ole-energized to require the engineer to manifest his vigilance upon the approach of his train to a signal at danger and thereafter at repeated distance intervals by actuating a manually operable device,` and means for actuating said prising, a, brake exceeds the perniiissive speed, and other.

means i'or rendering said appliance active including means moved in the same direc` tion as long as active and etiective after the train has traveled a predetermined distance in dangerous territory unless a suitable manually operable device is operated at rcpeated distance intervals ot travel.

l. An automatic train control system comprising, a normally energized stick electro` responsive device which it cle-energized et :tects an automatic brake application', two independent means 'for maintaining said device energized, one of which is effective so long yas the train is traveling in clear territory and a predetermined distance in danger' territory, and the other oi which includes a device rotated in the same direction so long as traliic conditions are dangerous, which device is eiective it a suitable manually operable device is operated repeated dis tance intervals.

5. In an automatic train control system, vehicle-carried apparatus,comprising a permissive speed means Which applies the brakes of the train it the speed` is excessive, means for initiating` said permissive speed means under dangerous traiflic conditions ahead for rendering it active after a given interval of vehicle travel from the point initiated to impose a minimum speed restriction, distance governed. means rotated in the same direction so are dangerous for suc cab signal and a device lor long as trai'iic conditions speed after a givenL distance oi?y vehicle travel from the point at which said minimum speed restriction was imposed, and means including a manually operable member tor preventing the automatic brake application'regardless of speed provided said manually operable member is operated at predetermined successive intervals o vehicle travel from the point at which said minimum speed restriction was initiated.

6. An automatic train control prising, automatic means for effecting a brake application it the speed ot the train is excessive for particular conditions of tratiic ahead, means for eiiecting` an automatic application ot the brakes regardless of the speed of the train, manually operable means operable by the engineer for preventing an automatic brake application by said last mentioned means it operated just prior to the initiation of such application, means system ceinessively actuating ay imposing` anV automatic brake. application regardless ot for inflicting a` penalty ifran, automatic brake application isl effected because the engineer has 'tailed to operate said manually operable means, and means Jfor preventing the inflicti'on or" said' penalty eiiective iii traffic conditions aheadrlear up before the train has been brought to. a stop.

7. Car-carried apparatus for automatic train control systems comprising, a brake set,A ting appliance, means ioractuating said appliance to effect a brake application if the speed ot the train is excessive, another means for actuating` said appliance regardless of the speed of the train, means for making an acknowledging act including a manually op erablo acknowledging device which it momentarily operated before said another means actuates said appliance is adapted to prevent actuation or' said appliance, and means for protecting said manually operable device against misuse requiring said device to be returned to its normal position in order to complete the acknowledging act,

S. Car-carried apparatus for automatic train control systems comprising, a brake setting appliance, means for actuating said appliance to eii'ect a brake application it the speed ot the train is excessive, another means for actuatingy said appliance regardless ot the speed of the train, a stick relay which if energized prevents said another means from actuating said brake setting appliance, an acknowledging push button, a pick-up circuit or said relay including contacts closed when said push button is depressed, and a 100 stick circuit for said relay including contacts closed when said push button is in its normal position.

9. Car-carried apparatus for automatic train control systems comprising, a brake 105 setting appliance, means for, actuating said appliance to eiiect a brake application it the speed of the train is excessive, another means for actuating said appliance regardless oi the speed of the train, a stick relay which if 110 energized prevents said another means trom actuating said brake setting appliance, an acknowledging push button, a pick-up circuit or said relay including contacts closed when said push button is depress-ed, a stick 115 circuit for said relay including contacts. closed when said push button is in its normal position, and means 'for dropping` said stick relay When said another means is ner longer inv condition to actuate said brake set- 120 ting appliance.

10. In an automatic train control system, vehicle carried apparatus comprising a permissive speed means Which applies the vehicle brakes il' the speed is excessive, means 125 for initiating said permissive speed means When dangerous trailic conditions are encountered for rendering it active after a given distance of vehicle travel from the point initiated to impose a minimum speed 130 restriction, a normally energized electro-responsive sticlt device acting When de-ener gized to impose a brake application and bring the vehicle to a stop, distance responsive means initiated by said permissive. ,speed means at a pre-determined distance or' vehicle travel from the point at which said permissive speed means is initiated and operated continuously when initiated so long as the vehicle is proceeding under dangerous traliic conditions ahead, apparatus associated With said permissive speed meansfor deenergizing said stick device substantially When said permissive spe-ed means is initiated, apparatus associated with said distance responsive means for de-energizing said stick device at predetermined distance intervals after said distance responsivel means is initiated, and manually operable means acting if operated substantially When said permissive speed means is initiated and at predetermined distance intervals after said distance responsive means is initiated to prevent the de-energization of said stick device.

l1. lIn an automatic train control System,

vehicle carried apparatus comprising a normally energized electro-responsive sticli device, acting when de-energized to initiate an automatic brake application and bring thev control means at a predetermined distance from the pointI at which said speed control means is initiated, and acting when initiated to de-energize said stick device at predetermined distance intervals so long as the ve Vhicle is proceeding und-er dangerous traiiic conditions, and manually operable means acting if operated and returned to its normal position substantially when said speed control means is initiated and at said predeterinined distance intervals under dangerous traffic conditions to maintain said stick'device energized.

In testimony whereof I aix my signature. i

. CHARLES S. BUSHNFLL.

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