US1469408A - Automatic train-control system - Google Patents

Description

AUTOMATIC TRAIN CONTROL SYSTEM Filed Sepu. '7, .1916

L. E @WEGE ET AL AUTOMATIC TRAIN CONTROL SYSTEM 1916 5 SheeiswSheet 2 Filed Sept, '7

@1cts 2 19236 1,469,408

| E. DODGE ET AL AUTOMATIC TRAIN CONTROL SYSTEM Filed sept. v, 1916 5 sheets-sheet 07 y di, m

Patented Oct. 2, 1923.

uNVrEDv STATES PATENT OFFICE.

LYIJIAN E. DODGE AND NEIL D, PRESTON, OF ROCHESTER, NEW YORK, ASSIGNORS TO GENERAL RAILIVAY SIGNAL COMPANY,

NEW YORK.

OF GATES, NEW YORK, A CORPORATION OF AUTOMATIC TRAIN-CONTROL SYSTEM.

Application filed September To all fio/0m it may concern Be it known that we, LYMAN E. Denon and Ninn D. Pnas'roN, citizens of the United States, and residents ot the city oi Rochester, in the county of Monroe and State ot New York,- have invented a new and useful Automatic TraimControl System, ot which the following is a specification.

rlhis invention relates to systems for automatically controllin the speed of railway trains.

ln the type oit systems tor automatically controlling thespeed otrailway trains to which this invention more particularly relates an arbitrary quantity, which corresponds to and varies with the actual speed t the train, is establishedon the train, and this quantity is compared with another like arbitrary quantity which is caused to vary as the train progresses and to assume at each point .in the travel of the train a value corresponding to the permissive speed desired at that point, suitable devices being employed to cause an automatic application of the brakes in case the result of this comparison shows that the actual speed o i the train exceeds they desired permissive speed.

In one physical embodiment ot this type of system, the arbitrary quantity'l corresponding to the actual speed is indicated or 'established by the position ot a movable member or part which .is caused to assume different positions by a suitable speedV responsive device, and the arbitrary quantity corresponding to permissive speed isV indi-A catedA established by a cam operatively connected Vto the. wheels ot the train and moved in accordanceq with the distance traveled by the train aiter passing a predetermined reterence point in the rear. ln applying this system to practical railroad operat ing conditions the principles and practices oi" the well known block signaling system are in general adopted, that is, the railroad is divided into space-units, called blocks, and the system is so constructed and arranged as to provide for the proper control of the speed of trains in each ot these blocks according to whether or not the next block in Y advance is' occupied by another train, and also according. tothe fixed hazards or other conditions associated with that block which require limited speeds throughout certain portions of saidblock. In this adaptation 7, 1916. Serial No. 118,817.

of the system the reference point at which the cam is set into operation is the entrance end of each block. It is a well known tact to those skilled in the art-of railway signaling that the different blocks for a practical railroad are in practice of different lengths, and further that the fixed hazards requiring limitations of speed are different in dilterentV blocks and are located at different points in these blocks, so that in applying` this system to practical railroad conditions it is necessary to make allowance for the variations in the length of block and for the variations in the position and character of the fixed hazards. Heretoiore it has been proposed to make this allowance for the variations inthe lengths of blocks by shifting the cam used for establishing permissive speeds so as to change its initial position, and to select the shifted position ot the cam desired by selecting mechanism comprising in general certain devices carried by the train which cooperate with other devices located along te track. The large number of different positions of the cam which may be required, however, usually necessitates a large number of selections7 and this in turn requires a complicated selecting mechanism capable of giving this large number ot' selections. With these considerations in mind7 the primary object of this invention is to devise an arrangement and construction ot parts such that the shitting of the cam used for establishing permissive speeds to any desired position may be obtained by causing the cam to be moved at different desired points in the travel of the train in `proportion to a predetermined distance traveled by in a simplified form one physical embodi-` ment of the parts orf-the system embodying this invention4 which are carried by the train or vehicle; Figs. 2, 8 and l are diagramnn'itic views of portions of a railroad track which illustrate some of the conditions which the system embodying this invention isr capable of satisfying and which show an arrangement of trachw'ay circuits capable of 'controlling the mechanism illustrated in Fig. l to obtain the desired results, the per missive speeds at the different points along these portionsof track being illustrated ac* cording to the well known method of blotting curves; and Figs. 5 and G illustrate modified forms of devices for Acontrolling the mechanism shown in Fig. 1.

. Referring to the accompanying drawing, particularly to Fig. 1, the numerals' and 2 designate portionsv of the track rails of an ordinary railroad track; `and the numerals 3 and idesignate a pair of wheels of a rail-` way train or vehicle, these wheels being connected by the usual axle 5. According to the particular embodiment of the invention illustrated, the impulse for controlling the mechanism on the trainis transmitted Yfromv the track to the train by means of a Contact shoe and ramps, and in Fig. 1 this contact shoe isshown in a simplified form as comprising a plunger 6 mounted in a bracket 7 so as to move vertically, said i with each other and which are so arranged and constructed that when the plunger' G is raised the contact spring 1() yis separated fi'om the contact piece11. y

Secured to the. axle 5 is a beveled gear 12 which meshes with a beveled pinion 13 fixed toa shaft 1d. The shaft 1a is arranged to drive a shaft 15 preferably by means of suitable mechanismV which operates to drive the shaft 15 in the saine direction regardless ofthe directionof rotation of the shaft 1fl. ln the construction illustrated, this automatic reversing mechanism conn I prises a beveled gear 1G fixed to the shaft 1.11

.17 and 18 againstv endwise and meshing with two? beveled pinions 17 and 18 which are loosely mounted on the shaft 15 and are arranged at diametrically opposite points with reference to the beveled gear 16, suitable collars 19 being secured to the shaft-15 to hold the Vbeveled gears movement. Mounted on the shaft 15 between the beveled gears 17 and 18 is a sleeve 20 having a-loiigitildi'nal slot 21 therein through which passes a im. 22 5X6@ te the Shaft 15 'The ends of the sleeve 20 are provided with clutch teeth 23 facing'in opposite directions and the hubs of the beveled gears 17 and 18 Y purpose of this reversing' mechanism is to.V .obtain the same direction of rotation of 'the shaft 15 and its connected parts'iegr-.rdlessA of the direction in which the vehicle carry the mechanism is headed.

r Y n l1 Y v'1 .Ehe speed responsive device G illustrated if; of the centrifugal type, similar in con-- struction to the well known centrifugal governor, and comprises a collar 25 fixed to the'shaft 15 and a. collar 26 loose on the shaft 15. l* neeted to linas 2S which are pivotally con* nected tothe collars 25 and 26, respectively. The collar 26 is formed with acircumfeiential groove 30 in which are Ydisposed.

rollers or iins 31 secured in the bifni'cated ends of an .arm 32 which is pivotally niountet'i on a fixed pin and which is rigidly connected to a downwardly extends.

gearing being used to turn the shaft 41y and the cani 4t2 fixed thereto inaccordance;

withthe distance traveled by the train, and the group of gearing .f being need to shift the position of the cani the sgroup of gearing` fi, a U4car lf3 is A y fixed to the shaft at), and loosely.mounted ou the shaft'llf() isV en aria Llll lutving an upsta dine extension 115. 'Carried by lthe arm 1l are two interineshing gears i6 and 17, the gear 4:6 vbeing also in inesh with Vthe gear i3.v

llivotally connected tothe extension -11-.5 is

a pawl 18 which is pressed in a counterclockwise direction, as viewedin Fig. 1, by a spring t9 against a. stoppin .50. is fixed to theshaft al and -isjarranged in the same plane as the gear 17 .and the pawl 4.8. Below the arm 474 is'- positioned an elect/romagnola 52, hereinafter termed the sights 27 are pivotally con ice ice

A. gear 51 cani-starter maglie@ an armature 53 whichis secured to a rod 54( connected to the ai'in the i'od 5l beingj urged upward by a compression spring 55 interposed loetween the yoke of the electi'oinagnet 52 and a colh` nfied to said rod 5-1.

l he gretig ot' gearing Y comprises ay geul; 56 secured to the'sliatft l() and .nieshinwith a geal- 57 securedto a gear 5S. The gear drives a `gear 59 to which is l'iXed a gear G0` which drives a gear 61. Vllflounted to turn about the saine axis as thev gear (3l is an erin G2 vvliieh carries tivo i intei-Ineshing gears, and 64;, the gear 64- being also in mer-fn Win the gear 6i. The aiiin 62 is .nuwed'by an electioinagnct 65, hereinafter termed the selecting magnet, in substaidtiall')7 the saine way as the anni 54.- is n'ioved, the electoinagnet 65 having an mature 6G securedy toV a rod 67 which is connected to the arm 62 and which is urged to the position shown in Fig. libyn coinmi'ession spring 68. `Arranged inthe saine )lane with the geaiq is a freai (39 which s oosel;7 mounted on thefshaiit 4L and this 5 i' is provided with a counterweight which tends to rotate said gear in a eeluvise directionas viewed in F l, to 'he point where a stop 7l carried by said gea? strikes a fixed stop 72. The gear 69 provided with an integral lueF or `pi-oie; io..r 73 wvhieh is arranged to strike aiin 74 looselv mounted; on the shalt ncirclingithef shaft all is asigning c endA of Vwhich is lixed to the r .and V:the other endv of which is .fixed to saidjshattu 41; and fixed to the anni 7e' is valpin 76 which is adapted to engage a pin 77 fixed to the shalt al so as to nievent movement of the arni 74 in a clockwise direction, as viewed in Fig. i, relativel;7 to the'shaftz41.

The cai'n l2 is Aprovided With a counterweight V7S which is so positioned as to cause the cam 42 to tend to assume the position shown in'llg. l. f

The comparison between the arbitrary quantity corresponding to the actual sneed, which is established as a posit-ion of the ai'ni ,9st, with the :arbitrary quantity coiiespendingP to the permissive speed which is cstablislicd bythe cam 42,' is obtained bj! an ai'ianlcment `ol parts comprising a lltmting;1 lever 79 pivotally connected at its lower end to the ann 3l and vcai'ying at its upper end a. iti-e j ievmuble roller S0 arranged to bea? against the edge el' the cani 12. Pivotally connected to thelniiddle peint ot the floatingT level' 79 is a linl; 8l which is pivotallyconnected to an arm 82 of a sector-shaped ineinbe- 83 mounted or'rotation upon a fixed pin Sfl. the arm 82 beingspring pressed in a di'ection away from the floating level" 79 lof; a'teirisionV spring 85. The curved edge of the sector-shaped-member 83is provided with two siouldejl's 8G and 87, the lnupose ot' which will be more lully exfilained here ina'teif. lQ'ispos-ed adjacent to the sectoishaped ineiiibei' 85? is a lixed bloei; S8 ot suitable insulating material on which are supported thifee contact lingers SS), 9() and 91. One et these contact lingers 89 cai'- i'ics a i'ollei' S9 which bais against the curved edge et the sector-shaped ineinbei 83. The contact lingers S). Si() and 91 aic resilient. and arev arranged as to tend to nieve to the lett, as viewed in Fig, l, and associated with each of these Contact lin,n es ie a fixed stop 92 which stufves to limit this movement toward the left't. these lined stops 92 toi' the ditli'ei'ent contact vtingcis being so located to permit the lcon tact .lingen 89 to move farther to the l "c than the contact linger 90, and the contact tlngei' 90 to move lfaithei to the lett than the Contact lingei` 9i, loi.' `he purpose inoie fully explained hereinafter.

lt coiiteinplated according vention that the train to which aiuglied will be equipped with olV anton iticallv operated biales oi othei` toi" icta ing its` movement. and .in ,ne embodiment oil the invention illust ated to this .inthe .system Sonie 'lioiin ision made lon operating the Well oi? air brakes. This sjvetein o too Well known to ifecuiie i" descr ition7 y ig. ins no A the present invention` only that palt thm-eet has been slieivn as is necessary to illus; 'ate the naait nei' olE control oi: 'the biales ...ie automatic ti i control system. system ot aii brakes coinpiises a train pipe 93.

and as Well `known h v thosl C1illed in i i r the ait. tleventiue' of tl ze i iatic amilication o i hating a stein .ing 06 tending 'to open position. The valve 94 is held in .its closed position h v a solenoid 97, which when energized pulls upward upon the valve stern 5 with sulicient torce to ovcwgenie the tension oli the spring lt is contemplated accordingr to this vcntimi that prim' to the anta .ptitY 'L l" catimi el? the brakes siffuil will lie @given to ini that it is neces the` speed of his .i being autfenati( i. i

pipe 1 1 is controlled bj; e; el

. fl valve designated genei'al j Tangeinent and construction ot loaits pre- Cil llO

lierred is that in which the Whistle '98 is Y mechanism carried by the train. Also carried by the train is a jViick-up relay l? having va neutral. armature and a polarized arn'iature 106.

rlhe i electrical connections between the dillereut parts shown in Fig. 1 will not be oointm1 out in detail since these electrical lins and the dil'ereut controlling established will be set iforth at in the following description of the on. 4 v

ring to 2 in the accompanying drawing, there is illustrated a portion of a railroad track over which the normal direction of trailic is 'from lett to right, as indin cated b-yithe arrow .l. rlhe track rails 1 and 2 oi this portion oi' track are divided by insulating joints 10'? into track circuit blocks, designated A., l, C, D and E, only the entire length of the blocks ll, C, D and ll lbeing` shown.

The length et these. bloc-ks has been selected arbitrarily to illustrate certain conditions which may occur in practice, and

` it-is to be understood that the particular arrangement of blocks of the particular relative length illustrated has been merely chosen` as an example and that the same conditions may be tound in various other com- Y bin ations. is illustrated, the block B is the longest block, the block D the next longest, the block C the next longest and the block ill the shortest, the block Ebeing preferably the shortet bleek occurring on the railroad equipped with this system. Flach o1c these blocks is provided with the Well known norinally closed track circuit comprising a track battery 103 and a track relay, the track relays for the blocks il, C, D and E being -designated 109,110, 111, and 11.2, respecside or the track or between 'the track rails,

and are supported in any suitable Way but insulated ifi-om the track rails so that the Vcontact shoe or plunger 6 (sec 1) will make electrical. contact With` these ramps and will also be raised vertically by the en? gageinent with these ramps as the train successively passes them. particular exception ol' the shortest block E, the ramp at the entrance to each block is kdivided in any suitable manner into sections insulate-d from each other, for instance, the

ramp RB adjacent to the entrance end of the block B is divided into tivo sections RB and R131 insulated from each other, the line .of division or-insulation being shown conventionally and being approximately opposite to the adjacent insulating joint 1021. Associated with these sections or ramps, 'as the sections lll-3 and BB1, are controllingcircuits including sources olf current which serve to establish a dililercnce oi. potent-iai between a ramp section and the adjacent track rail. The dilerences of potential between the ramp sections which may be established not only may vary in intensity but are also or" different polarity in the manner and for the purposes hereinafter explained,

Above the portion of the track above mentioned there are shoivn in Fig. 52 a series of curves which indicate permissive speeds at different points along this portion of track. These curves are drawn in accordance with the Well known method of plotting speed and distance curves lto rectangular coordinates, and are derived from the braking curves oli the kind of equipment used on the railroad. In these curves thev horizontal distances represent the distance of travel ot the train over the successive blocks to any arbitrary scale Which .corresponds in scale with that to Which the length of the blocks is shown, and the vertical distances represent permissive speeds to an arbitrary scale ol speed in miles per hour, or in any other' curves lor the dillcrcnt blocks are based on the same principles and'a'description ot one will suiliice for all. .Referring to the block B, the curve c the curve drawn as a heavyiiull line) represents tor cach point in the length of the block B the proper permissive speed lor that point'ivhen the train should proceed cautiously with a view oi' coming to a stop or to av predetermined low speed by the time it reaches the end of block l. This curve c is derived 'lroni the braking curve for the kind of equipment traveling on the railroad, and generally speaking, indicates a permissive speed Afor each point in the length of the block B at which a train may be traveling at that point and yet by an application ot its brakes may be brought to a stop bctorethe end. of the block B is ln general, with the` loo v i l which seeinsjbest adapted Vto the particularV Yconditions ot the railroad 'in question. The

ill!

reached. It can loe -secn from Fig. 2 that the. curve c intersects the horizontal line Z), indicating` a predetermined low speed, at -a short distance troni the end ot the block B, and the curve c is so drawn in this case 'be canse the jinirticnlar physical'embodiment of theV invention contemplates that the train will not he brought to a complete stop at the end o'l each hlecl hat to a predetermined low speed. 'll he distance between the point where the curve c intersects the liney and the end oi the hloclr l may he ot any length desired and is adop'` d principally as a tactoi' of safety.

rthe signilicance of the curve c may he hetter understood hy some illustrations; and tor example, assume that, While the hlock C is occupied hy another train, a train enters the block P) at a speed oit' approximately L15 miles per honicorresponding to-the permisire speed indicatedbyv the curve c at the mii-ance to the block B. Under rthese conditions it can he seen that it isnecessary tor the liralies to he immediately applied to the train entering the hloek B in order that this train may he brought down to a predetermined low seed hy the time it reaches the end ot the block B. Suppose, however, that a train enters the block 4B at a lower speed et, Yloi' instance, 30 miles per hour, and thatthe hloct: (l is occupied hy another train;

' under these conditions, it is not neete the first-mentioned train and this iay proceed some distance into the loci-c l he tore it is necessary to have the ili hes ailiplied, this distance heilig readily f l n ined by continuing` the horizontal line responding to `the speed ot this train to the point where it intersects the curve c.

some cases, when a train enters the "i, there will he clear track ahead and `3cr lor the train to proceed through r B at as high a speed as' consistent and the sate speed which the attain in `the hlock B is indicated 2 hy the dash line y?. This sate t lepeinls in general'npon speciallocal (renditions, sach as curves, (langere sdovwi ei des. and lil-e iixed hazards; and turtl'iee more the speed ot the train while it is travelii'iej through the 'liloclq B not only must he limit-eri 1with regia dto the lined hazards in jhe hloclq hat mest L in, the end ot the hloek'C. The limitation ir speed required hy the last-mentioned con.

dition is indicated hy the curved portion 201 ash l e y) near the exit end ot the and lare siniilarto Fig. 2 and te other conditions which may he inetwith in practice and which are satisfied hy the system 'embodying 'this invention; but since the principles involved in the curves and in the controlling raiinps- 'and partial circuits Vtherefor are v"the same in Figs. 3 and Ll as has already been 'explained in connection with li'i'gp2, it is deemed un necessary to enter `yinto a detailed 'explanation oit the meaningr ot the various-lines "and symhols shown in Figs. 3 and L1.

Betere taking up in detail the traclwafy circuits lorv estahlishingl differences- Ol Apotential ot the different cl'iaracters VVbetween the Vseveral ramp sections ofthe different blocks shown in ligs. 2, 3 and 4, the effect 'of these ditl'er'ences of potential ot 'different characters upon the `operation of the system Will he iirst pointed out. Referring to Fig. 1, a single lramp section R is' illustrated as lprovided With a Anumloer of :partial circuits hy means of v which the -diierences ot potential of the ditl'erent characters necessary for the proper control of the mechanism onthe train may he established hetweenthis ramp section R land the track rail' 2 by `the ma-r `the switch 114is moved to itsfnext upper position into contact Withthe conductor 120,

the partial circuit'terminatingr at `the ramp section R andthe track rail. 2 vthen includes only one battery 117, and this electrica-l condition ot the ramp section A iR-is conveniently termed negative loiv Voltage on the ramp section B. Then the switch 114iis moved still further intocontact withthecondiictor 122'tlie partial circuit terminating `at the track rail 2 and the ramp section k'R is as fellows: Commencing at the ramp R, con- 'dnctm' 113, switch 114, conductor 121, hattcries 122 and 123 in series, and conductors 12aand 119 to the track rail 2. This last traced partial circuit includes the twovhatf tei-ics 122and 123 in series, but these'hattcries are so arranged inthis partial circuit that the difference ot potential is of an opposite polarity to that established when the .sr-:itch is in the position-shown in Fig, 1 and is 'assumed to he ot positive polarity. This last-mentioned electrical condition of the ,i ip section R is conveniently termed posiire high voltage on the ramp section B. lllhen the switch 11st is moved still farther into contactwith the conductor 125, the partial circuit` terminating at-the ramp section ioo R and the track rail 2 includes only the battery 123, and this electrical condition of the ramp section R is conveniently termed positive low voltage on the ramp section l. lVhen the switch 114 is moved to its lippermost position into contact with the contact button designated 126, the ramp section R is disconnected from all source of current, and this electrical condition is conveniently termed Zero voltage on the ramp section R.

peTaZ/OW-Reierring to Fig. 1, the parts are shown in the positions which they assume when the train is traveling through the shortest block, as the block lil, and the next block in advance is not occupied by another train. In other words, the parts olf the mechanismv carried by theV train are shown in Fig. 1 in the positions which they assume when this mechanism is set tor the shortest blockr and when traiiie conditions are such that the train may proceed through that block without regard to any other train ahead. With the parts in this position the control relay SC is normally energized by a circuit which may be traced as follows: Commencing at the battery 127, conductors 12S and 129, relay SC, conductors 130 and 131, armature 101 in its upper position, con- .fductor 132, contact piece 11, contact spring 10, and conductors 133,'134and 135 back to the battery 127.

When the control relay SC is energized a signal indicating proceed is displayed in the engineers cab, this signal being shown as a green lamp Gr which is supplied with current by a circuit which may be traced as follows: Commencing at thebattery 127, conductors 128- and 13G, armature 102 oi the relay SC in its upper position, conductor 137, lamp G, and conductors 138, 139,140 and 135 back to the battery 127.

Also, when the con rol relay SC is energized,.the cam-starter magnet 52 is supplied with current flowing along a circuit which maybe traced as follows: Commencing at the battery 127, conductors 128, 136 and 141, armature 103 of the relay SC in its upper position, conductor 142, windings of the camstarter magnet 52, and conductors 143, 134 and 135 back to the battery 127. When the partsare in a position. shown in Fig. 1 there is imposed a limitation upon the maximum 'speed which the train may attain at any angular space between the radii is made proportional, according to some arbitrary selected scale, to distance. To illustrate, suppose that when the cam is in the position shown in Fig. 1 the length of the radius of the cam to the point where the roller 8O bears against the edge of said cam represents according to the arbitrary scale chosen a speed oi 25 miles per hour, then, as the cam is rotated in a clockwise direction through an angle, for instance, of 5 degrees, which it is assumed `is equivalent to a distance of 50 i'eet, the radius or the cam at this point 5 degrees from its position shown in Fig-1 is made greater according to the arbitrary scale selected so as lto establish a lower permissive speed o the value desired at a point 50 feet from the point at which the permissive speed of 25 miles per hour is desired. 'lheradii et the cam 42 increase with respect to a stationary point as the cam turns in a clockwise direction to establish lower permissive speeds because of the particular construction and arrangement ot parts by means et which the comparison oi permissive speed and actual speed is obtained, but it is apparent that this particular type ot cam may take various other iorms and accomplish the same result.

Referring to the means used tor comparing permissive speed and actualV speed, the arm 34 is operated by the speed responsive device or governorV Gr in accordance with the actual speed of the train, and as the speed ot the train increases, Vthis arm 34 assumes positions more and more to the lett of the position shown in Fig. 1, thereby moving the lower end of the floating lever 79 more and more to the left of the position shown in Fig. 1. Suppose that the cani 42 remains stationary, then the point where the roller 80 carried by the upper end of the heating lever 79 bears against the edigi, oi said cam remains stationary and the upper end oi" the floating lever 79 becomes a .fixed fulcrum point.y Consequently, as the lower end of the iloating lever 79 is moved more and more t0 the left from its position shown in lilig.V 1 by the increasing Aof the actual speed o' the train, the link S1 is moved more and more to the lett and causes clockwise turning 0i the sector-shaped mem'- ber 33 against the tension of thespring 85. Then the sector-shaped member S3 turned in a clockwise direction tar enough to bring theshoulder 3G opposite to the roller 39 carried by Athe contact. linger S9. the contactfmgerg S9 and 90 are caused. to move together by their resiliency toward the lett; and since the contact linger 91 is held against movement to the lett by its stop 92, the contact lingers 90 and 91 are separated. *l t The separation or ine Contact fingers 90 and 91 interrupts normally closed circuit which prevents the sounding pas voi" thewvarningWhistle 98,1this normally Vsounded a Warning signal.

dmv traced as follows:

closed circuit being traced as follows: Commencing at kthe battery v144, 'conductor 145, contact in'gersQO and 91, conductor 146, electrically.operated valve 100 control linfar the Whistle 98, and conductors 147 and 14S back to the battery 144. It the sectorshaped member 83 is moved still further in the clockwise direction and the notch 8T at its edge is brought `opposite to the roller 89, the contact linger 89 may move still furv cuit for energizing' the solenoid 97 and holding the valve 94 in its closed position is interrupted, said normally closed circuit be- Coxnmenoingr at the battery 144, conductor 145, contact `fingers QOand 89, conductor: 149, solenoid 97 and conductors 150 and 148 back to the battery 144.

From the foregoing it can be seen that when the actual speed of the train attains` certain limitingr permissive speed Ywhich is determined by the length of the radius ci the cam VWhich is in .line with the roller S at that instant, the brakes are automatically applied, and also prior to the automatic application of` the brakes there is The Warningl sig-nal serves to advise the engineer that the speed of his train is nearly as great as the highest' speed consistent With safety at the point along the. track Where his train is located at that instant, and from this theengineer knows thathc should take measures to reduce the speed of his train or other ivise an automatic application ot the brakes v, 'll result. It can also be seen from the toregoi j that, as the cam 42 is moved, the permissive speed for the train 'established by said cam ischanged by reason of the fact that the radii of the cam whichv determine what the. permissive speed shall be vare charmed. According t0 the particular constructiony and arranofement of parts illus-r trated, the cam 42 is moved in a clockwise direction to cause a reduction in the per- Vmissive` speed, and the rarrangement and construction ot parts is further such as to enable the cam 42 `to be moved in this clockwise direction exactly incorrespondence with the distance traveled by the trainA This movement of the cam"42 is accom-- plished by deenergiz-ing the camlstarter magnet thereby permitting the spring to move the arm 44 upward `and bring the `car 47 into mesh with the `gear 51, so that the cam shaft l41 is directly connected to the Wheels of the train and is caused to turn `gradually in a clockwise direction as the vheels oil" the train revolve". The radius ot the cam 42 at its te@ or point is designed to correspond tothe predeterminedlow per- `missive'specd hereinbe'forc pointed out, and

the radii of the cam 42 are designed to decrease in proportion to the increase in the permissive speed in accordance with the braking curve ot the train, exemplified by the `curve c `for the block B hereinbeiore explained. Hence, the angular distance according to the arbitrary 'scale selected be tween the point or toe of the cam and its position when it is first connected to the' Wheels of the train is equivalent to the length of a block, and it can be seen that the movement of the cam 42 as the train progresses through the block is caused to establish gradually decreasing pern'iissive speeds in accordance with the braking curve ot' the train. If the cam 42 has the position shown in Fig. l when the camstarter mag'- net 52 is d energized and the cam is connected toy the Wheels of the train, the cam Willhe turned in a clockwise direction iter enough after the train has traveled a certain distance to bring the toe or point the canropposite to the roller 3() and compel the speed of the train to be no greater than the predetermined low speed; but it the cam is shifted in a counterclockivise direction to a new position before theJ cam starter magnet 52 is deenergized and the cam is connected to the Wheels ot the traiiny the maximum permissive speed for the train may be altered. y

The cam-starter magnet is controlled by the armature 103 of the control relay SC, being energized so as to disconnect the camshaft 41 from the Wheels 0i the train when said. relay SG is energized and its armature 103 is in its upper position, and being decnergized so as to connect the cani-shaft 41 to the wheels of the train when. the relay SC is deenergized and its armature 103 is in its lower position. Consequently, when it is desired to compel a reduction in speed of a train it is necessary to decnerlrize the control relay SC, and this is accomplished Awhen the contact shoe G strikes a ram i section to which zero voltage is applied beca le, when said contact shoe engages such a ramp section, said shoe is lifted and raises the contact spring out of contact with the centact piece 11 so as to interrupt the circuit hereinbeiore traced for 'normally enereiaine` the control relay The decne ragion of the control 'relay SC causes its armature 101 to drop and open another break in the above mentioned circuit so that, after the" "L f'. 1.,',1 other bieah is establieiieo ,mnnriftod to a pa in the positionsliowii in 1 vContact slioeleayes engagement with the raiiip and is returned to its lower position by the spring-,8, nevertheless this Circuit will not be ro-established. Also, when the control relay Si) is deenorgized the eireuit heieinbelfore traced. Ytor lighting" the green lainp G is broken and another circuit tor ii gri iti n ahlisliel as follows: @oiiinieneiiig i Mii, e: etofs'fffl and 166, armatures 102 in its lower position, sondrio tor 151, yellow lamp and conductors 152, i, :ind 165 bari, ,to the liiiitteij-,f .127.

ln this way, "wlieiieyera train passes a raiiip seetion to which :aero voltage .is apn plied, the Control relay is 'dee iergized,

:fh the resin `i eab is eliangec to a Caution iiiion, thel Cain-starter iiiagiiet is do i" ed and the camshaft L11 directly eolito the Wheels olf the train, and aniii the control eireiiit'ior the relay t5@ s0 that this relay niust be energized by soiiie other circuit heitere its normally Closed cire-uit is eli'eetive to retain it eiiergize'. lhe control relay SG, ai'iter it has once been deeiiergiyed, may be dica Yreenergiiaed by raisiiio the` armature 165 of kthe battery 127, condiietors 128 and 129, re-

lay SC, conductors 160 and 159, armature 105 in .its opper position, and conductors 160, lll() and 135.baelr to the battery 127. llhe construction and arrangement olf parts is suoli that the souree oil;l current Capable ot raisin the ariiietnro of the relay l) must be ot liirg'h yoltag'ewhon the relay SC is deene ,zel at' the time. vl-lssiiine that the switch 114; is either iii the position shown in 1 or in the position in Contact with the conductor 121 so that either negative high io-Q'o or positiye high voltage is applied to the ramp section Vlflieii, who the Contact `:noe '6 strilestlie ramp section lt, the partial oir/nit along); the tinel terminating; it the ts'ncl rail :ind the reino section lil, rtial eii'eziit on the train including the piek-Jup relay ll so that einfi'ent n'isiy Plow :troni the batteries alongV the track through the piek-iii) relay l? and raise its armature 105. '.llio eoiny lete energizing ciieiiit i'or the relay l when the switch 1141 wir', 1V and when the Controlli-clay tl@ is doens" iyod .is as tollows: flloii' niiciiir' t the ramp ,it section R, ooinert shoe 6, ooi ietoi 153, preventive i'esistanee 1511, conductor 155, relay P, oon- Vfl diietor 15o to the Wheels and afi-le of the train, thence to the track rail 2, along oonyellow lai/np Y to indicate eaiiv the proceed indication iii Yalter. Y

conductor 115,V switch 1141, and conductor 116 back to the ramp R.

The resistance 1514 is selected so that Sullicient current will flow through the relay l) .and raise its armature 105 only in Case high voltage is applied to the partial circuit on the train. 6 str1 lios a rainp section R to which only low mltage is applied and il the Control *relayV Si@ is doonorgized, there will not be sullioiei'i enrient flowing' through the preventiveresistanco 154: and the relay P to raise its armature 105. Il the control relay SC is energized, howeverat the time Contact shoe 6 engages a ranip section, as the ramp section 1, to which only low Volt 'ge is applied,

nevertheless Sul'licient current will flow through the relay P to raise its armature byieason o'j tlie'taet that the armature 011 of the oontrol'relay SC is now in its uper position and establishes a low resistance niiit consisting or' conductors 157 and 158 ,round the preventive resistance 15-1.V

Frein the foregoing it can be seen that the armatures of the control relay SC may be caused to drop, or il in the loWei-position iiiay be restored again to their upper position or may not` be again restored to their upper position, according' to the voltage applied to the ramp section withV which the Contact shoe 6 engages. The volt-ageapplied to the several ramp sections alongv the tract: is determined by the traclcway circuits in the iiiaiiner more fully oxplainedhereinlll a train passes a iainp section, as the ramp section R, to which voltage of one polarity, herein assumed to be negative voltage, is applied, the polar armature 106 of the relay P is shifted to the right, as viewed in Fis'. 1, so as to supply current to theV Selecting; magnet 65 bya circuit which may be traced as follows: Coiiiiiieiieing' at the battery 161, conductor l162, selecting insgo'l the train so that, when the `ofear is in ine-sh with thevg'ear 69, the `hgear 69 is turned in a ooiiiitereloekwise direction as the Wheels oit the train turn. rllliis Coiiiitereloelwise inoi'feineiit t the gear 69 Causes a Corresponding coiiiiterolockwise ii'iovenieiit ot' the shalt 411 and the cani 112 by reason oi the ifaet that the projection 73 on the `rear 69 bears apgaiiistthe 741, and the tension of the spring 7 5 causes thesliaft 411 to follow Consequently, if the Contact shoe the movement of the arm 74. The pawlV 48 does not interfere with this movement of the shaft 41y in the counterclockwise direction, but at the same time it acts to hold the shaft 41 against returning under the influence of the counterweight 7 8 `from whatever position it may be moved to. As soon as the contact `shoe 6 leaves engagement with the ramp section to which negative voltage is applied,

or passesfrom sucha ramp section to another ramp section to which posit-ive voltage is applied, the armature 106 is returned to its neutral position in the first case or to its 4 lefthand position in the second case, thereby interrupting the circuit for the selecting magnet 65. The deenergization of the selecting magnet permits the spring 68 to return "the arm 62 to its normal position shown in Fig. 1, whereupon they gear 69 is returned to the normal position shown in Fig. 1 by the-action of the counterweight but the pawl 48 by engaging with the teeth of the gear 51 holds the cam-shaft 41 and the cam 42 against return'movement.

The selecting magnet 65 is energized very shortly after the contact shoe 6 engages a vpreferably'so arranged and constructed that the 'interval ot time required to move the gear 63 intoV mesh with the gear 69 after the 'contact shoe 6 first engages a ramp section is substantially the saine as the time required to move the gear 63 out of -mesh with the gear 69 after the Contact shoe leaves the ramp section, so that regardless of'the speed of Vthe train as it passes said ramp section, providing the train maintains a( substantially uniform speed, the movement given to the gear 69 is proportional to the length of said ramp section. In this Way the cam 42. may be shifted in a counterclockwise direction to varying extents andheld in the shifted position by causing the contact slice `6 to engage a ramp section of the desired lengthft'o which negative voltage is applied. For the proper control of the control relay SC the pickup relay P it is necessary that high/voltage should be applied to a ramp section sometimes and lowvoltage at other times; but it is contemplated according to kthis invention that the polar armature 106 of the pick-up relay P will respond to either negative high voltage oi' negative low volt-- age,`and for this purpose, if desired, the pcla r armature 106 may be operated by a separate relay arranged in parallel with the relay P, but not including in its circuit the preventive resistance 154..

Having described the operation of the mechanism carried by the train and the manner in which it may be caused to control the speed of the train as desireui by the electrical conditions and lengths of the ramp sections, it is possible to consider now some of the different conditions likely to occur in practice which may be satisfied by this mechanism. Referring to Fig. '2, one condition is illustrated by the blocks B 'and C, namely the condition in which a long block having a high maximum permissive speed is followed by a shorter block having a lower permissive speed. Assume that the train equipped with the mechanism shown in Fig. 1 is in the block A and about to enter the block B and further assume that neither the block B nor the block C is occupied by another train. The ramp section RB, under these conditions has negative high voltage applied thereto by a partial circuit which may be traced as follows: Commencing vat the ramp section RB, 'conductor 165.armature 109.1 in its upper position, conductor 166, battery 167 conductors 168 and 169, battery 170 and conductors 171 and 172 to the track rail 2. lVhen the Contact slice 6 carried bythe train in question first engages the ramp section RB the selecting magnet 65 is energized, as explained hereinbefore, and commences a counterclockwise movement of the cam-shaft 41 from Vits initial position shown in Fig. 1. This initial position of the cam-shaft 41 is such that the cam 42 establishes a certain permissive speed as for instance that of approximately 25 miles per hour as indicated by the horizontal ldot and dash line designated datum line. This datum line preferably corresponds to a permissive speed which is the same as the maximum permissive speed for the shortest block on the railroad, as the block E, although such an arrangement is not essential. As explained hereinbefore the counterclockivise move- Vment of the cam-shaft 41 continues so long as the contact shoe remains in engagement with a ramp section to which negative voltage is applied, and furthermore the movement of the cam-shaft 41 is proportional to the length of that ramp section. Consequently, the cam 42 is shi ted in the counterclockwise direction through an angle proportional to the length of the ramp section RB. The different and increasing ermissive speeds established by the cam 42 uring this counterclockwise movement While the train is moving over the space equal to the length of the ramp section RB is represented in Fig. 2 by the heavy dash line d and the permissive speed established by the cani 42 after its movement has been completed is indicated by the heavy dash line 79, this latter permissive speed being the maximuml permissive speed desired for the block B. The

vpartial circuit associated with the ramp `mencing at the ramp section BB1, conductor 4174, armature 110*2 in its upper position, conductor 175, positive terminal of battery 17 6 and conductors 177 and 178 to the track rail 2.A This positive low voltage on the ramp, sectionBBL causes vthe shifting movement of the cam 42 in a countercloclrwise direction toV cease, and also serves to keep the control relay SC energized. Consequently, the train may proceed along the block B at any speed less than the predetermined mais imum speed, indicated by the line j), established by the cani 42 in a position to which it is now shifted. The above operation of selecting a position of the cam 42 toV correspond to the length of the block next to be entered by the train is typical of the different blocksfin the railroad, and in discussing the operation of the system for the other blocks illustrated in Figs. 2, 8, 4 it will not be necessary to point out this feature vof the operation again in detail.

Since the block C is shorter than the block B a train cannot enter the block C at as high a speed as it may enter-the block B line p. For ythis reason it is necessary to -make provision for automatically compel'- ling aireduction inV speed ofthe-train near the end of the block B so thatrthe train may enter the block C at a speed not higher than the permissive speed indicatedv by the line 200. This is accomplished -by locating between lthe ends of the block B a ramp section 180 to which `zero voltage is applied, so that when the train passes the ramp section 180 the control relay SC is deenergized,

the cam-.starter magnet 52 is deenergized and the camshaft 41 connected to the` wheels of the train, as explained hereinbefore. In this way, the train is compelled to reduce its speed and maintain a speed lower than the curve of permissive speed'indicated by the dash line 201. The ramp section 180 is located at such a distance from the end of the block B that the reduction in speed in accordance with the curve 201 will bring the speed ofthe train to the same as or slightly below the maximum permissive speed for the block C indicated by the line 200.

Vhen the train reaches the ramp section RC to which negative low voltage is applied, as will be apparent by an inspection of the partial circuit associated with said ramp section, the selecting action is again commenced by reason ofthe fact'that the armature 10G of the relay P is shifted to close the circuit for the selecting magnet 65;

but since only low voltage is applied to the ramp section BC, and since the control relay SC is deenergized at this time, the arma-ture 105 of the relay PV isfnot raised. Conse quently, while the gear 69 is being turned from its normal position shown in Fig. 1 in thecounterc'lockwise direction and is carry ing with it the arm 74,fthe cam-shaft 41 is being gradually turned in a clockwise direction by reason of the fact that the gears 47 and 51 are in mesh, the spring75 ,permitting this relative movement Vof the cam shaft 41 and the arm 74. -In other Words, while the mechanism for selecting a predetermined position of the cam'42 is acting the cam 42 is also compelling a further reduction in speed, and this operation of the parts continues until the contact shoe 6 passes from the ramp section RC onto the ramp section RC1. y 1` Y Since it is assumed that the block C is not occupied, negative high volt-age is applied to the ramp section RC1, the partial circuit for establishing this negative high voltage being readily apparent. p Consequently, when contact shoe 6 of the train passes onto vthe ramp section RC1, the polar armature 10G is not affected and maintains the! selectingl magnet 65 energized so as to continue further movement of the cam-shaft 41 in the counterclockwise direction, armature 105 of the pick-up relay l? is raised, however, by this high voltage and causes the energization of the control relay SC and the resulting energization of the cam-starter magnet 52, as hereinbefore explained, so that the arm 44 is lowered to bring the gear 47 out of mesh with the gear 51. The extension 45 of the arm 44 is moved at the same The neutral gagement with the teeth 51 before the gearv 47 entirely moves out of mesh with the gear 5l thereby holding the gear 51 and the camshaft 41 in the position which they have at that time. This position of the cam ,42 establishes a predetermined maximum speed for the train which is indicated by the short Y horizontal line 202 invFig. 2. The arm 74is at this time in position corresponding to the position of the cam-shaft 41 due to the cooperation of the pins 76 and 77, and the ear G9 has not yet been moved far enough Arom its initial position to bring the lug 73 thereon against said arm 74, but as the movement of the gear continues and the train reaches a point indicated by the point where the dash line Z1 intersects the short dash line 202, the lug 73 strikes the arm 74 and carries it and the cam-shaft 41 further through is determined by the length of the ramp sections RC and. RC1,or the reasons hereinbefore explained, and consequently saidposition of the cam 42 is attained When the contact shoe 6 passes from the ramp section .RC1 ontothe ramp section RC2.

If the block D is not occupied at this time, the ramp section RC2 has positive loiv voltage applied thereto, or, if the block D is occupied, said ramp section has zero voltage applied thereto as will be readily apparent from the trackway circuits shown in Fig. 2. In either case the polar armature 1.00 is moved to interrupt kthe circuit for energizing the selecting magnet 65, thereby disconnecting the gear 69 from the Wheels of the train and permittingt to return to its initial position, the cam-shaft il and the cam 4t2 being held in the position to which they have been moved bythe pawl 48. The arrange-- mentdescribed which causes the cam l2 to be moved by the progress of the train to a mechanism so as to establish the higher pery missive speed (indicated by the line 200) is used with the understanding that the inaccuracies of the mechanism with such an ai'- rangement would be on the side of safety;

but it is obvious that such an arrangement is not compulsory and may be modified if de- Y Vsired so that the permissive speed established by movingtlie cam by the progress of the train from the ramp section 180 to the end of the block C may be the same as V the permissive speed established lby thel cam for the block C.

From the foregoing it can be seen that the I speed of a train may be properly controlled in the block B so that the train ivill not enter the shorter succeeding block C at a speed too high to prevent it being brought .to the predetermined loiv speed within the limits of the block C,.and further that a new position of the cam is automatically selected by the length of the ramp sections Re andl RC1 so as to accord With the, maximum permissive speed for the block C and its shorter length. In this Way provision is made for controlling the speed of the train under pro- Vceed conditions in passing through a long block into a shorter block. f

Suitable provision vmust be made4 by this system, however, so as to properly control the speed of the train in the block B under caution conditions,l that is, when the block C is occupied by another train, and also to lcord with the block C. lTo obtain a clear understandinor of how the system of this in ventionsatisties this condition, vassume that a. train equipped with a mechanism shown in lVig. l is in the block A and that While the block B is not occupied by a train, the block C is occupied. When the contact shoe 6 of the train in question engages the ramp section RB the mechanism acts to select the position of the cani l2 to accord with the block B in the saine Way as hereinbefore described;

Vand when the contact shoe 6 passes onto the ramp section HB1, the cam has been moved to the position desired and is held in that position. Under the conditions. assumed, since the bloclr C is occupied, zero voltage is applied to the ramp section BB1 by reason ot the fact that the track relay 110 is deenergiaed and its armature 1102 is in its lower position. Consequently, for the reasons hereinbeiore explained, the control relay SC is deenergized, and by the reslutant deenergiZa-tion oi the can'tstartcr magnet 52, the

cam-shaft il is connected to the Wheels of the train, so that as the train progresses through the block B, the permissive speed Ltor the train Ais continuously reduced in accordance with the curve c with a view of bringing the tram to the predetermined 10W speed by the time it reaches the end of the block B.

As the train progresses through the block B and passes the ramp section 180, no action is produced on the mechanism carried by I v10G is shifted While the neutral armature 105 is not affected, vthis result beingdue to the tact that the control relay SC is deenergized at this time and the preventive resistance 154s is included in the circuit for the relay P so as to prevent the lifting of its armature 105 although not` preventing the shifting 01"" the armature 106. Consequently, i'vhile the control relay SC and the cam starter magnet 52 are not afectechthe selecting magnet G5 is energized, and the driving of the gear 09 to select a position of the cam to accord with the block C commences. cam-shaft llcannot respond to this movement of the gear 09 because said camshaft is connected to the Wheels, but the spring 7 5 permits the gear 69 to continue its moves ment the same as if the cam-shaft were free to move. Then the train reaches the ramp section RC1 the movement of the gear 69 continues, since this ramp section has either negative high or low voltage applied thereto. lf the train Which Was assumed to formerly occupy the block C is still in this block, the ramp section RC1 has loW negative voltage appiled thereto, which is not eiiective to` The raise the armature V105 and reencrgize the control relay SC. Under normal conditions the engineer will bring his train to a stop at this point before reachingthe ramp Vsection RC2 and will Wait until the tra-in ahead leaves the block C. When the train ahead leaves the block C, the voltage applied tothe ramp section RC1 is changed to negative high voltage and this high voltage causes the armature 105 to be raised so asy to reeiiergize the cani-starter magnet 52 and disconnect-the camshaft from the Wheels oi the train. ,The camshaft 41 is now free and Yrotates in a counter clockwise direction unthe Contact shoe 6 passes onto the ramp section RC2 the gear 69 is disconnected from the V'wheels of the train in the same way as previously described leaving the cam in the new position to accord with the block C.

The electrical condition of the ramp sec- Y' tion RC2 depends upon whether or not the Vcam (indicated by the line 200).

tion, according to the length oil the ramp block D is occupied, low Vvoltage being applied to said ramp section if the block D is not ocnpied, so that the train may proceed at any speed less than lthe maximum permissive speed established by the new position of the If the block D isoccupied by a train, zero voltage is applied tothe ramp section RC2 with the re- -sult that the control relay SCYis deeneigized and the-connection of the camshaft 4l with the wheels of the train produced in the same -Way as hereinbefore described, so that als the train progresses it must keep its actual speed below its permissive speed indicated by the heavy line c1.

f The blocks C and D have been selected to illustrate the condition where a short block is followed by a longer block. Assuming that the position of the cani to accord with the block C has been properly selected as hereinbeore described and assume that'the train in question proceed-s through the block C until it reaches the ramp section RD. Thisl ram `section RD has applied thereto either liig i or low negative volta-ge1 depending on whether or not the block D is occupied by another train. ln. either case the action upon the mechanism on vthe train is the same as liereinbe'lore described and results in the gear G9 being shifted toa posisectiion RD, so as to establish the maximum permissive speed proper for the block D (indicated bythe line 203). As theconf tact shoe G of the train passes from the ramp section RD onto the ramp section RDl the movement of `the gear 69 ceases since the voltage yapplied to said ramp section iis'iw either zero voltage or low positive' voltage, according to whether or not the next block E in advance is occupied by another train. The presence of a train in either the block D or the bloclrE has the same effect upon'- a train passing through the block C as the presence of'a train in either the block C or theblock D'has upon the train passing through thev block B, which has Vbeen explained hereinbeifore.`

The blocks D and E `illustrate a condition analogous Vto 'that illustratedbytlie blocks B and C, namely, the condition where a long block is followed by a sli-ort block. The block E is shown as the block liavingthe" maximum permissive speed the sameV as the maximum permissive speed `established by thecani i2 in the position shown in Fig.

l, and as explained hereinbefore this permissive speed is indicated by the horizontal" line designated datum line and is prefer-V ably selected with the idea thatthe bloc-k which zero voltage is applied,being placed at the proper point in the block'E for the same purpose and with the same eilect'as theiramp section 180 vis placed in the block B. It should be noted, however,` that since the position of the'cam i2 to accord with" the conditions in the block Eisthe same as the position which the cam 42 does assume under normal conditions, due to the counter- Weight 78, it is unnecessary to cause anyse lected movement oi' the gear (S9 atv the en-' trance to the block E, and consequent-ly, a single ramp section RE tofwhich positive voltage is applied is sufficient, whetheror not high or low positive voltage is applied to said ram-p section being determined traffic conditions in the block E and the next block in advance in theV same wayl as `hereinbeiore described in connection -with the blocks B and C. y Y

Occasion may sometimes: require thata' trainV shouldbe compelled-'to passover 2a shortsection of a long block at a comparatively low speed, vas for instance, where there is a sharp curve or other fixed hazardsbetween the ends of a long block. Such a condition is illustrated by the block G in Fi 3. The condition illustra-ted by the block is assumed tobe such that throughout a portion of 'the length of this block thetrain should not be allowed to exceed a comparaiso L tively low speed indicated by the heavy dash line 205. In Fig. 3 the heavy dash line 20G indicates the maximum permissive speed for the block F, and the curve c4 indicates the limiting permissive speed for the train in the block F under caution conditions. The ramp section RG at the entrance to the bloclr G is arranged to have either negative high or negativelow voltage applied thereto according to Whether? or not the block G is occupied, and this ramp section RG is made of such a length as to result in the cam 42 having a position at the time` the train actually enters the block G such as to establish a permissive speed for the train of a-magnitude indicated by the line 20G, In vievv of t-he region of low maximum permissive speed in the block G it is necessary to compel the train after it enters the said Lblock to reduce its speed, and this result is accomplished by placing a ramp section HG1 at the entrance to the block G to Which Zero voltage is applied, the effect `of this ramp section RG being to vset the cam 42 into motion to compel a speed reduction in the same Way as hereinbefore described. By the time the train reaehesthe ramp section 182, the indicated permissive speedof the train is substantially the same as the low premissive speed 205 desired, and. consequently, it is unnecessary to to continue the movement of the cam in its clockwise direction, and it is only necessary to disconnect the cam-shaft 41 from the. Wheels of the train and hold the cam-shaft in the position it then has. This is accomplished by applying positive high voltage to the rampv section 182 which has the effect of raising the armature 105 of the relay P, Without effecting the selecting magnet 65, so as to energize the control relay SCV and the cam-starter magnet 52. The cam-starter magnet 52 being energized moves the arm 44 downward and brings the gear 47 out of mesh With the gear 51 While the'pawl 48 is thrown into engagement with the teeth of the gear 51 at the same time. The train novv proceeds under the maximum permissive speed limitation indicated by the line 205 until it reaches the ramp section 183 Which is located at such a distance from the end of the block G that the train may be brought to the predetermined low speed before reaching the end of said block. lt is apparentfrom the foregoing discussion that if the block H is occupied by a. train it is n ecessary to set the `cam 42 into motion at the point Wherethe ramp section 183 is located so as to compel a reduction in speed of the train according to the curve c5. On

'the' other hand, if theblock H is not occupied by a train, it is permissible for the train to proceed past the ramp section 183 at any speed lessthan the permissive speed indicated by theline 205. The controlof the mechanism on the train to accomplish either of theseA desired results is obtained by arranging the trackway circuits, as clearly shown in Fig. 3, so as to apply low positive voltage-to the ramp section 183 When the block H is not occupied, and to apply zero voltage `to the ramp section 183 when said block His occupied. y, Y

According to the assumed conditions illustrated in Fig. 3 the maximum permissive speed (indicated by the line 207) for the block H is'higher than the maximum permissive speed indicated by the line 205, and consequently it is necessary to move the ca-m 42 to a higher lspeed position. This is accomplished by the use of ramp sections energized with the necessary value and polarity of current in accordance with the same principles hereinbefore discussed. That is, at the proper point at the necessary distance from the end of the block G the contact shoe 6 of the train engages the ramp section RH which has permanently applied thereto 10W voltage, and this voltage, being negative, commences the selecting movement of the gear 69, Without., however, changing the condition of the control relay SC and the camstarter magnet 52. At the proper point in the block G the ramp section RH.l is placed andis arranged so that either negative high or negative low voltage Will be applied thereto in accordance With traffic conditions in the block H. This voltage applied to the ramp section RH being negative continues the selecting operation of the mechanism, and further serves, by reason of the fact that `it is high or low voltage, to reenergize the control relay SC or not reenergize this relay When a. train reaches the end of the block G after having been compelledy lto reduce its speed by reason of the presence of la train in the block H, according to Whether or not a second mentioned train is still in the block H or has moved from that block into the next block in advance.

. There may be occasions Where it is desired to have the maximum permissive speed for a Y train under proceed conditions throughout the kportion of the length of a block near its entrance end less than theV length of the block requires, and such a condition is illustrated in Fig 3 by the block H. In this case it is assumed that the maximum permissive speed desired for a portion of the length of this block at its entrance end is that'indicated -by the line 207, although the length ,of the block is such that a train might enter the blockH at a higher permissive speed `and yet be stopped by its brakes before the end of the block H was reached. To satisfy this condition the cam 42 is moved to a positionY by the lengths of the ramp sections RH and BH1 before the train enters the block H so that the shifted position of the cam corresponds tothe desired permissivel speed indicated by the line 207, and then the cam is held stationary during the travel of the train from the entrance end of the block II until it` reaches a'ramp section 184. This ramp section 184 is 'placed at such a distance from theend of the block H that even if the train Weretravelingas fast as indicated by the line 297, nevertheless by a prompt Vapplication ofthe brakes itcould be brought to the predeterminedlow vspeed before reaching the end of the block I-I. In other words, the location of the ramp section 184 is so chosen that the cam may beset into operation at this point and ivillact to compel a reduction in tlie'si'ieed of the train according to thev curve c,i f the presence of a train in the block I next in advance requires such a reduction in' speed; The 'partial circuit for the ramp section 184 is controlled by the track` relay` ofthe block I so as to have low positive voltage applied thereto when said block I is not occupied,'and also Vto'liave zero voltage applied thereto when said block I is occuyeis `ied. Theinovement of a train from the block II into the block I is accomplished by the saine selecting action and control as hereinbefore described and need not be pointed out in detail. Y

A still further condition Which may beV satisfied by the system embodying this invention is .illustrated by the block Kin Fig. 4. 'In this case it is assumed that a sharp curve or other fixed hazard makes it necessary tolimit the speed of the train throughout the portion of the block K, as between thevertical dot and dash lines 190 and 191 to a comparatively low maximum speed such as indicated for instance by the heavy horizontal dash line 210. And it is further assumed' that ,the part of the block succeeding this portion is of such physical characteristics Vthat a much higher permissive speed is proper, such as indicated for instance by In controlling the mechanism on the train toobtain the proper control of thespeed of the train and to satisfy 'these 'conditions the same'principles hereinbefore discussed are carried out. The

Vramp sectionv RK is made of such length and vhas nega-tive voltage applied thereto so` as to produce the desired shifting of the cam 42; and ther-amp section RK1,'to which zero. voltage is applied, acts toV set the cam into operation from the initial position to Which it has been shifted, thereby resulting in the continual reduction in the vpermissive speed jof the train as indicated by the line 209. When the train reaches the ramp sec- .tibn 185 further speed reduction ceases by reason of the fact that this ramp section has high positivevoltage permanently applied thereto. The cam 42 isthen'held stationary throughout the portion of' the block K Where' thel restricted speed is desired, Whereupon the contact 'shoe engages theramp applied.

section 186 to which negative loiv voltage is The length of thisv ramp section 186 is such as tov cause a shifting of the cam 42 to a higher permissive speed positiony de-l sired and indicated by the line 211.. The ramp section 187 islocated, at such a distance from the end of the bloclrK as willpermit the cam to be set into operation if necessary at'the ramp section1874 and cause'thc cam toindicate decreasing permissive speeds as indicated by the curve ci. At the end of the block It lthe proper selection of the cam to accord with the next block `inad-` vance andthe proper' control of the controlrelay SC in accordancevvith traic conditions in said next blockin advance is obtained in the same'way as hereinbefore describedland need not be further discussed In the embodiment of the invention pre viously: described and explained the distinc-y should perform the 4function of controlling the speed control apparatus', is determined by arranging to have either positive or negative ycurrent supplied by these ramp sections to the mechanism on thetrain, the devicelfor controlling lthe position. of the cani bei-ng responsive to Vcurrent of one polarity but not to current of the other polarity. The distin'cV tion between the portions of the ramp which shouldY act to cause a shifting-ofthe cam or which should perform only'the function of controlling they speed control apparatus may be attained in other Ways, however,and one modified arrangement is illustrated in Fig. 5. Inthis modified construction shown in Fig. 5, the portion of the ramp R1 'which it is desired to have act to cause thecam to be shifted is made to move the contact shoe to a higher position than the other portion of the ramp which performs the function of controlling the speed control apparatus. In this modification the contact shoe vvis illusica trated as an angle lever 192 pivotally con- V.

magnet-,65 when the shoe is raised to its uppei'most position, said circuit being -tracedasV follows: Commencing at the battery '127,

conductors 128 and 198, selecting magnet 65,

conductor 199, contact piece 195 and conductors 189, 134 and 135 back to the battery 127. In other respects the mechanism carried by the train is constructed the same in the modification shown in Fig. 5 as in the arrangement of parts illustrated in Fig. 1, and similar controlling ci-rcuit for the relays SC andL P are used as indicated by the corresponding reference' characters in Figs. l and 5. It is not necessary to divide the ramp R1 shown in Fig. 5 into separate sections insulated fromv each other, and the voltage applied to the ramp `is either high, low or zero voltage o f the same polarity according to traffic conditions for the same reasons and with the same eli'ectl as previously described. lVhile the contact shoe 192 is in engagementwith the portion of the ramp R1 between the points designated 196 and 197, which portion 1s higher than'the other portion of' the ramp, said-contact shoe is raised to its uppermost position and energizes the selectingr magnet and it can be seen that the length of the higher section ofthe ramp R1 determines the position to which the cam Will be shifted. Itis also apparent that the contact shoe may be caused to assumedii'erent positions in other directionsY than vertically and produce the same result. A

In the modification shown in Fig. 6 the selection of the position of the cam is determined by the length of the ramps located at proper points along the track but on the opposite side of the track from the ramps used to control the speed control apparatus on the train. In this modiiication there are shown tWo contact shoes, one on each side of the vehicle, and each Contact shoe is also illustrated as an angle lever 220 operating a rod 221 to which tivo contact pieces 222 and 223 arevsecured and insulated therefrom. The normally closed circuit for energizing the relay SC includes in vseries the-contact pieces 222 and 2221 of the contact shoes 220 and 2201 located on opposite sides of the vehicle; and the contact springs (indicated as arrows in F ig. 6) which cooperate With said contact ,pieces on the respective shoes are so .arranged that when. the vehicle is traveling in the normal direction of traiiic indicated by thearrow T the contact shoe which is located upon the righthand side of the train at that instant will cause an interruption of the circuit for the relay SC upon engagement Withv a ramp ,R2 located on the righthand sident the track. In case the other contact shoe on the lefthand side of the vehicle traveling in the normal directionof traiiic .engages a ramp R3 on the lefthand side otthetrackthe contact piece 222 or. 2221 of this contact shoe will not open the circuit for the relay SU. The normally closed circuit for energizing the relay SC inthe modification shown in Fig. 6 may be traced as followsrCommencing at thebatterry 224:, conductor'225, relay SC, conduc . tors 226 and 227, armature 101 ot the relay S'Cin its upper position, conductor 228, contact vpiece 2211, conductor 229, contact piece 222 and conductors 230 and 231 back to lthe battery 2,34. The conductor 153 connected ing the selecting magnet 65.

.. lecting magnet 65.

to one terminal of the Winding of the relay l) through the resistance 154 and conductor 155-is connected to both contact shoes by the.

conductors 232 and 233. The circuit for the selecting magnet 65 may be traced as follows: commencing at the battery 2311, conductor 235, selecting magnet 65, conductor 236, thence either along conductor 237, contact piece 2231 and 238 tothe conductor 239 and back to the battery 234, or along conductor 240, contact piece 223, conductor 24:1, to said conductor 239vand 'back to the battery 234. `When the contact shoe, as contact shoe 2201, on the lefthand side of a vehicle traveling in the normal direction of trafiic, engages a lefthand ramp R3, the contact piece 2231 of that shoe is moved into position to close the circuit for the selecting magnet 65; but when a contact shoe, as the contact shoe 220, locatedon the righthand side of the vehicle engages a righthand ramp R2, the contact piece 223 is not moved in position to close the circuit lor energiz- In other Words, the selecting magnet 65 is energized so long as a lefthand contact shoe on a vehicle is in engagement with a lefthand ramp, but is not affected by the engagement of a righthand contact shoe of the vehicle with a righthand ramp. The lefthand ramps R3 merelyserve the purpose of actuating the lefthand contact shoe and consequently have no voltage applied thereto, Whereas the voltage applied to the righthand ramps R1V is either high, low or zero voltage of either polarity in ac cordance with traffic conditions in the same Way as hereinbetore explained. The arrangement of contact shoes shown in Fig. 6 permits the vehicle to be headed in either direction While traveling in the normal direction of traflic Without interfering with the proper operation of the parts, otherwise it would be possible to arrange the contact shoe on one side of the vehicle to control the relay SC and the contact shoe on the other side of the Vehicle to control the se- It is apparent that various changes may be made in the particular embodiments and modifications of the invention shown in the accompanying drawing and hereinbefore described Without departing from the invention; `and broadly considered the invention is not restricted to the use of a contact'shoe and ramp for obtaining the controlling impulse from the track to the train, nor is. it essential that the controlling impulse used for shifting the cam to different positions in accordance With intervals of distance Vbe obtained by the same devices which cause the impulses for controlling the speed control apparatus; Furthermore, While the particular embodiments of the invention shown and described contemplate the shifting of a cam or equivalent device to different positions

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