US2113847A - Train dispatching system for railroads - Google Patents

Description

April12,-1938. RQLEAKE 2,113,847

TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed April 25, 1929 2 Sheets-Sh eet 1 o N u N NV NTO ATTORNEY FIG, LA.

April 12, 1938. R. c. LEAiKE TRAIN DISPATGHING SYSTEM FOR RAILROADS 2?. Sheets-Sheet '2 Filed April 25,, I923 Patented Apr. 12, 1938 UNITED STATES PATENT OFFICE 7 2,113,847 I TRAIN DISPAT'CHING SYSTEM FOR RAIL- ROADS Richard C. Leake, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application April 25, 1929, Serial No. 358,075

15 Claims.

This invention relates to train dispatching systems of the synchronous selector type, and more particularly to'means for increasing the number of uses to which a'channel circuit may SR andSMRbeingof -the polar permanent mag net stick type, that is, these relays are operated into a position depending upon the polarity of the current applied thereto and remain in their last energized position even though ole-energized,

*5: be put by stopping the system at a channel or by reason of the action of permanent magnets 5' channel point during its operating ,cyclei associated therewith. These relays SR and SMR,

In synchronous selector type train dispatching 5 are controlled through the medium of the consystems, suitable synchronously controlled control relay CR, which control relay CR is of simitacts located at adispatchers office and at the lar construction, and is controlled through the various way stations along the railway; track medium of the synchronous selector SS The 10 are used .to make available a plurality of se dispatchers office, (see Fig. 1A) is connected with quentially closed message circuits. in accordthe various Way stations through the medium of ance with the present invention, it is proposed a stepping wire 3, a common wire (3, a starting to give a distinctive indication at a way station wire 4 and a message wire 5. At each way sta- 1-5 when a particular channel circuit is closed for tion is located a line relay, of which the line I5 I an appreciable period of time, as distinguished relay at the way station shown has been desigfrom the control given if such message channel nated LR). t is closed only for the usual stepping'period. An- Referring now to the dispatchers office equipother feature of the present invention resides ment, which includes a miniature track layout.

in the energization of a relay located at a parconforming with the railway system to which 20 ticular way stationthrough a circuit local to the present invention is applied, and of which, said way station only in the event that the synfor convenience, miniature passing id n rs chronous selector is caused to hesitate when a, only has been shown. Associated with the east particular channel -circuit is closed. g r A endiof this passing siding ps is an indicating 2.5 Other objects, purposes, and characteristic fealamp I, which manifests by its illumination the tures of the present invention "will inpart be occupancy of the detector track circuit at the understood from the illustrations 'in the accomeast end of the passing siding PS. Also, assopanying drawings and in part be pointed out in ciated with the east end of this miniature passthe description hereinafter. 1 5 ing siding ps are levers L and I having an In describing the invention indetail, reference interlocking lock rod LR. These levers through will be made to the accompanyingdrawings, in the medium of the synchronous selector system Which:- hereinafter described are adapted to control the Fig. 1A shows conventionally thedispatcliers switch machine relay SMR and the signal relay office equipment of one form of train dispatching SR. respectively (see Fig. 1B). In the dispatchers system embodying the present invention; ofiice'is provided a master synchronous selector '35 Fig. 1B showsthe apparatus at o 'e way station MSS, which in many respects is constructed like of this same system, so that, if Figs. 1A and 1B 5 the synchronous selector SS etc. located at the are laid end to end they constitute a diagramvarious way stations. matic representation of the system; and These selectors M88 and SS include, a main 40 -Fig. 2 shows on an enlarged -scale aportion shaft Ill driven by suitable spring driving means, 40 of the selector shown in Fig. 1A. such as a clock-work mechanism (not shown),

' Structura-Referring to Fig. 1B- of the draw include a rotating arm .II and a rotating arm ings, passing siding PS of a railway' system II respectively, escapement wheels l2 and I2 having many passing sidings, is shown, to which respectively, include'pallets l3 and I3 respecthe present invention has been applied. At the tively, and include magnets l4, I5, and L4 I5 4.

' east end of this passing siding have been shown respectively. The master selector MSS, is.=proa main starting signal- 2, and a-dwarfstarting vided with a slip ring l6 engaging the "rotating signal 2 The' east end of the passing'siding arm II and is provided with a slip ring 11 V PS has a track switch, preferably operatedby engaging the rotating contact segment 18, this a switch machine SM. Thistrack switch is procontact segment I 8 being'insulated from the con- 50 tected by the usual detector track circuit intact arm H by insulation I8, whereas the way eluding the track relay TR. The relays SR and station selector .SS T is provided with a slip ring SMR are used for .controllingwthe signal 2 and I9 engaging the rotatable arm H The way the switch machine .SM respectively, these relays station selector 38 also includes a stop magnet g5 20, which, when energized, disengages the stop latch 2! from the arm H This selector SS also includes inertia members 22 and 23, of which the member 22 closes contacts 2425 when the escapement pawl or pallet I3 is moved to its extreme left hand position, whereas the inertia member 23 closes contact 2326 and opens contact 23-21 when the pallet 13 assumes its extreme right hand position, this pallet I3 assuming either extreme position only in the event that the corresponding magnets I4 or I5 are energized for more than a predetermined period of time. The responsiveness or selectivity of these contacts 2425, 23-41, and 23-46 is in part dependent upon the inertia of the inertia members 22 and 23 and in part due to the time required for the direct current and the resulting magnetism to build up in the magnets I4 or I5 to a maximum value. In the arrangement shown no such inertia members have been shown for the selector MSS, but may be used when desired.

The line relay LR heretofore mentioned, is also one of the polar permanent magnet stick type, constructed similarly to the relays CR, SR, and SMR. In the dispatchers oflice is provided a master relay MR having separate windings 30 and 3|, for operating the contact 32 of this relay to either of its two extreme positions, this contact 32 remaining in the biased position to which it'was last operated by a toggle spring 33. This master relay MR alternately applies positive and negative potential across the stepping wire 3 and common return wire Cheretofore mentioned. The linerelay LR in the dispatchers oflice is operated by the potential applied across the stepping wire 3 and common wire C, which line relay LR controls the escapement magnets |4-l5 causing rotation of the synchronous selector MSS, which in turn controls the master relay MR by the alternate application of current to the coils 3i) and 3 i, so that these three devices MR, MSS, and LR are operated sequentially in rotation at a speed depending upon the inherent operating characteristics of these devices. The master selector MSS has also associated therewith a starting relay STR.

The indicating lamp I is controlled through the medium of indicating stick relays IR and 1R these indicating stick relays IR and IR being dropped by energization of the cancelling relay CAR, all in a manner to require two revolutions of the selector MSS before the relay IR is dropped.

Having now considered the various elements of the system, it is believed expedient to consider the operation of this system, in order to get a more clear understanding of the various operating characteristics and functions of the various devices.

Operation-Attention is directed to the fact that the system is normally at rest, and assumes the position shown, because the coil 30 of the master relay MR is de-energized, this being true because the contact arm I l engages the stationary contact 49 and connects the positive terminal of battery 41 to the starting wire 4, but since the starting wire 4 and common wire C are not connected together there is no current flowing through coil 30, even though the upper terminal of this coil 30 is connected to the negative terminal of the battery 4| and the lower terminal of this coil 36 is connected to the common wire C. In this connection it should be noted that movement of either the lever L or lever L momentarily connects the common wire C to the contact iii of the master selector MSS, thereby causing momentary energization of the coil 30 of the master relay MR through the following circuit: beginning at the positive terminal of the battery 4|, wire 42, slip ring I6, arm I I, stationary contact 4|], wires 43, 44 and 39 elements 4546--41-48, or elements 4950-5l52, depending upon whether the lever L or L respectively, have been operated, common wire C, wires 53 and 55, winding 3!] of the master relay MR, wires 56 and 51, to the negative terminal of battery 4|. With this circuit momentarily completed, the contact 32 of the master relay MR is operated to its right hand extreme position, in which position it is held by the spring 33. Attention is also directed at this time to the fact, that look arm 2| of the lock magnet 28 of the synchronous selector SS is now in its raised position.

Let us assume, that the lever L was the one which was moved, and that it was moved to its lower extreme position, when the circuit just traced was completed, and that it now assumes the same lower extreme position.

In order that the lever L may be moved from its neutral position, the interlocking lock rod LR must be moved to its left hand dotted-line position, locking the lever L so that it cannot be moved from its neutral position. This is necessary because the lever L places negative potential upon the message channel for controlling the relay CR and the lever L places positive potential upon the message channel for controlling the relay CR. Hence, it is necessary, in order that the relay CR shall be controlled, and in order that no short circuits shall occur, that only one lever be moved at a time. With the contact 32 of the. master relay MR now assuming its right hand dotted position in response to momentary closure of the circuit for the coil 30 of this relay MR, positive potential is applied to the stepping circuit and to the various line relays such as relays LR and LR in multiple, through the following circuit:-beginning at the positive terminal of the battery 61], wire 6|, contact 32 of relay MR, wire 62, stepping wire 3, the line relays LR, LR etc. in multiple to common wire C, wires 53, 63, B4, and 91, to the mid point of battery 60. Completion of this circuit causes the line relays LR and LR to be moved to their right hand extreme position, thereby causing the escapement pallets l3 and I3 to be moved to the right by completion of the following two circuits:(l) beginning at the positive terminal of battery 65 (see Fig. 1A) wire 66, contact 61, in a right hand position, wire 68, electro-magnet l5, wires 59 and 69 to the negative terminal; and (2) beginning at the positive terminal of battery 10, wire H, contact ,72 of the line relay LR in its right hand position, wire '13, winding of the electro-magnet I wires". and 15 to the negative terminal of the battery H3. The escapement pallets l3 and I3 are thus both moved to their right hand position thereby allowing the contact arms II and H to move one step into engagement with the stationary contacts i6 and 1'! respectively. With the pallet I3 now assuming its right hand position the slow-acting con-,

tacts and 25 are opened, the lock magnet 26 contact 76, the followingcircuit for the coil (ii of the master relay'MR is energized through the following circuit:-+beginning at the positive terminal of the battery Ill, wire 42, slip ring I6, ro-

tatablelarm II, stationary contact 16, wires I9 and ,80," winding of the coil 3|, wires BI and 51, back to the negative terminal of the battery 4!. Currentflow in this circuit causes the contact 32 of this master relay MR to be moved to its left hand position, and in turn causes the line relay LR and LR to assume their left hand position, thereby causing the following two circuits to be closed:(1) startin at'the positive terminal of battery 65, wire 66, contact Bl in a left hand position,'wire 82, electro-magnet I4, wire 59, back to the negative terminal of battery 65; and (2) starting at the positive terminal of battery in, wire ll,'contact 12 in a left hand pos-ition, wire 84, electro-magnet I4 wire I5, back to the negative terminal of battery lt. These circuits result vmaster synchronous selector MSS engages the contact 40, which stops the mechanismon that contact 4!! as it is not directly connected't'o the magnet 30 of the master'relay MR. as are the remaining contacts of even position of the master selectorj'MSS. I p QLet us now be reminded, that the'lever L? has been "moved to its lower extreme position, with thelo'ck ro'd LR .in its lefthand position to lock the lever L against movement and to unlock the leverflL {Bearing in mind now, that thelever 7L assumes the lower extreme position, the fol "86 andB'l, contacts 99 and i39 .vvires' 9B andlil;

lowing message circuit is closed when the contactarms .II and II assume the 5th position, begin-f ning at the positive terminal of a battery 85, wires contact 5th, contact segment I8,- slip ring I'l, wire 92, through message'wireii to the way station shown in Fig. 13, wire 93, slip ring I9, arm N of selector SS contact 5th of selector SS wires 94 and 95, winding of control relay CR. wire 96,

to the common return wire C, wires 53.63, and 54, to the mid-point of battery 35. 'Mom-entary closure of this message circuit causes the polar contact Ii! of the control relay CRto be moved to its right han'd'position and causes the {neutral V tential is placed upon the function'relayntojbe position for selecting saidiunction relay to bea contact Since the synchronous selectors MSS and SS do not hesitate or stop and stay at the contact 5th, the inertia member 23 is not operated and for this reason the signal relay SR. remains in 'or is operated to the left hand position;

o It will be noted here, that the polar contact II!!! of relay CR is moved to its respective extreme: position in response to the energization of relay CR, before the'neutral contact I98 of the relay CR assumes: itsenergized position, which is an inherent characteristic of polar neutral relays. Hence, po-

controlled as selected by polar contact H34,- only af tersaid polar contact I 04 has assumedits proper controlled. Also it will be noted, that if the synchronous selector SS pauses at the contact 5th for a period of time greater than the normal total channel time, that a positive potential is placed upon contact I68. However, if the; selector'fSS does not pause at comma 5th, 'a negative poten IE8 to assume anenergized position}.

follows-z-beginning at the negative terminal of battery lllll through wire I III, contacts 2I23, wire I02, slip ring I9, arm II of selector SS stationary contact 5th, wires 94 and IE3, neutral contact I98 of the control relay CR, wire I09, contactIM assuming'its right hand position, wire I05, winding of the signal relay SR, wires I06, Ill! and III, tothe mid-point of the battery Hit. It is thus noted, that movement of lever L to its lower extreme position did not move the polar contact of the signal relay SR.

Let us now assume that the lever L is moved to its raised position. It is of course noted that the movable contact 4'! of this lever is momentarily connected to one of the stationary contacts 4i], thereby momentarily energizing the coils 3B of the master relay MR for reasons heretofore explained,

therebyjstarting the synchronous selector system from rest. j 7

-"Also, it should be noted, that movement of the lever L to its raised position opens the contacts HB-IW" thereby disconnecting the stationary contact HE! of-the master selector MSS from the coil 3! of the master relay MR, so that the master relay MR is not operated when the master selector 'MSS' reaches the 5th position, and for obvious reasons the synchronous selector SS is also stopped at-the 5th position with the arm II engaging the stationary contact 5th. With the selector SS maintained in this position for an appreciable period of time the pallet E3 is moved tci its extreme right hand position, in which position contacts 23-2'l are open and contacts 23--26 are closed, and since the control relay CR still assumes its right hand position, because the same polarity is applied to control relay CR when the lever L assumes either itsupper or its lower extr'emefposition, the'following circuit is closed for the signal relay'SR, which operatesthe signal relay SR to its right hand dotted position:beginning at the positive terminal of thebattery Iili], wire I12, contacts 2I523, wire E62, slip ring I9, contact arm I I contact 5th, wires 94 and I03,

- contact I08, wire I09, contact I64 in its right hand L to its neutral position, thereby closing the following circuit for the coil 3| of the master relay MR:--beginning at the positive terminal of the battery 4I, wire 42, slip ring I6, contact arm II, fstationary' contact III), wire II 3, contacts IM- -IIB, wire IIB, contacts II9II8 wires II'I and'iifl, coil 3| of the master relay MR, wires IN 7 5 This circuit for energizing the relay 'SR is momentarily completed, which is traced as and 51, back to the negative terminal of the battery 4I. With this circuit closed, the synchronous selectors MSS and SS assume their stepping operation until they have completed theircycle of operation.

Let us now observe, how dropping of the track relay TR at one of the distant way stations, such as the way station shown in Fig. 13, causes the synchronous selector system to remain in operation so long as such track relay TR is de-energized, to thereby insure the transmission of the relay MR is closed:beginning at the positive terminal of the battery 4I, wire 42, slip ring I6, arm II, stationary contact 40, wires 43, 44, and I20, winding of the starting relay STR, wires I2I and I22, starting wire 4, wire I23 (see Fig. 1B) stationary contact I24, arm II stationary contact I25, wire I2'6, back contact I2I of the track relay TR, wire I28, common return wire C, wires 53, 55, magnet 36 of the master relay MR, wires 56 and 51, back to the negative terminal of the battery 4I. With this circuit closed, the starting relay STR will close its front contact I29 after a short interval of time, thereby shunting its own winding and allowing suificient current to flow to cause the master relay MR to move its contact 32 to its right hand position, thereby initiating the synchronous selector MSS from its zero position. In this connection, it may be pointed out that the starting relay STR, is purposely made slow-acting so that as. one cycle of operation is completed and the next cycle of operation of these synchronous selectors M88 and SS is started there is a sufiicient hesitation at the zero position to allow the various selectors equipped with lock magnets 20 to have their lock magnets energized in response to the slow-closing contacts 2425.

Also, in this connection it is desired to point out that in the event that a particular rotating arm, such as selector arm II has lost a step or two and has not reached its zero position, the

lock arrn 2| will be raised during the period of hesitation obtained by the slow-acting starting relay STR, and immediately dropped as the first step has occurred, so that the arm II of this synchronous selector. is not permitted to leave its zero or starting position when it reaches it, until the beginning of the'next cycle of operation of the system. In other words, the purpose of the lock magnet 20, which is operated only in the event that the line relays assume their left hand position for more than a predetermined period of time, is to bring the various selectors into synchronism, in the event one or more thereof get out of step by reason of some external influences, such as lightning disturbances, or the like. It should now beremembered that the track relay TR is de-energized and that the synchronous selector system remains in operation so long as the back contact I2'I of this track relay TR remains closed, the various selectors, such as selector SS being resynchronized each time a new cycle of operation is started. During each revolution of the arms II and II 1 of these synchronous selectors MSS and SS while the track relay TR is de-energized, the following circuit for the indicating relay IR is momentarily completed:beginning at the negative terminal of the battery 85, wires I30, I3I and I32, upper winding of the relay 1R wire I33, the sixth stationary contact of the selector MSS marked 6th, segment I8 of the arm II, slip ring I'I, wire 92, message wire 5, wire 93, slip ring. I9, rotatable arm II contact 6th of selector SS wire I34, back contact I35 of the track relay TR, wires I36 and I28, common wire C, wire 53, 63, 64, and 54, to the midpoint of the battery 85. Momentary completion of this circuit causes the indicating relay 1R to assume its energized position, thereby closing the following stick circuit for this relay IR which stick circuit includes the upper winding of the relay IR :beginning at the positive terminal of the battery 4 I wires I38 and I39, contact I46 of relay CAR, wire I4I, front stick contact I42 of the relay 1R wire I43, lower winding of this relay 1R wire I44, upper winding of the indicating relay 1R wires I45 and I46, back to the negative terminal of the battery 4|. With this circuit closed the indicating relay IR also assumes its. energized position, thereby closing its own stick circuit which may be traced as follows: beginning at the positive terminal of battery 4I, Wires I38 and I39, contact I4'I, of the relay CAR, wire I48, front stick contact I49 of the relay 1R wire I50, lower Winding of the relay 1R wires I5I, I45, and I46, back to the negative terminal of the battery M. It will be noted that energization of the indicating relay 1R through the medium of its front contact l52 closes an energizing circuit for the indicating lamp I. Also, it will be,

noted that at the end of the first revolution of the master selectorMSS the indicating relay-1R is de-energized by reason of operation of the cancelling relay CAR to its left hand and then to its right hand position, and that the indicating relay IR is de-energized at the end of the second revolution of the master selector MSS by operation of the cancelling relay CAR to its left and then to its right hand position all in a manner as more clearly explained in connection with the relays CR, IN, and IR in my prior a-pplication Ser. No. 332,132, filed January 12, 1929, now Patent No. 1,794,628 granted March 3, 1931, to which reference may be made for other features of the synchronous selector system.

Attention is'directed to the fact that the indicating relay 1R of course, Will 'not be deenergized at the end of thefirst revolution as just mentioned unless the track relay TR at the way station (see Fig. 13) has in the meantime assumed its energized position. In this connection it should be noted that when the track relay TR does assume its energized position, the synchronous selector system will operate for at least one complete revolution after this track relay TR has assumed its energized position, because in this event the common wire and starting wire are connected together through the following partial circuit:beginning at the starting wire, wire I55, back contact I56 of the relay 1R wire I51, front contact I53 of the relay 1R wire I59, to the common wire C, so that the coil 30 of the master relay MR is energized while the master selector MSS assumes its zero position by current flowing through the partial circuit just traced. The relay IR is of course deenergized at the end of this cycle thus bringing the apparatus to a stop until again initiated by either the movement of a lever, the dropping of a track 1 relay or the happening of some other event that is to be indicated in the dispatchers office.

Summary.Without tracing the various cir- Also, the movement of lever L? from its neutral position applies positive polarity to thecontrol relay CR over its respective message channel which is identical to the message channel. used for lever L It should be noted that, as either of the levers L or L are operated to a lower extreme position the synchronous selector system will not hesitate or stop when it reaches its 5th stepping position,

but that the synchronous selector will stop when it reaches its 5th stepping position when either the lever L or L are moved to a raised extreme position. It should be further noted, that the system does not hesitate at any contact when initiated by a way station, unless in response to the movement of a control lever simultaneously therewith or thereafter during the same cycle or cycles initiated by the way station.

..; In other words, the lever L moved to a raised extreme position, energizes the control relay CR with negative potential, and causes the synchronous selectors to hesitate at the particular message over which the control relay CR is energized,

thus energizingthe relay SMR'with. positive potential.

' synchronous selector SS inasmuch as the neutral disclosure.

contact I03 of relay OR is not in an energized position.

/ 'When the relay SMR is energized with positive potential, it causes the switch machine SM to unlock its track switch and operate it to its normal position; but when the relay SMR is energized with negative potential, it causes the switch machine SM tounlock its track switch and operate it to its reverse position. This control has merely been indicated in orde'rto simplify the Also, with lever L moved to a raisedextreme position positive potential is placed upon the control relay CR over its respective message channel, and the synchronous selectors are caused to hesitate at the respective message channel for the control relay CR, which energiz'es the signal relay SR with positive potential. With the lever I. moved to a lower extreme position, positive potential is placed upon the control relay CR over its respective messagechannel, but the synchronous selectors are not caused to hesitate, which causes negative potential to 'beplaoed upon the signal relay SR. Also, with lever L in a neutral position the relay CR is. not energized; hence the relay SR or the relay-SMR maynotsbe energized with either positive orne'gative potential, due to the hesitation, or non-hesitation. of the synchronous selector SS When the relay SR is energized with'positive potential, it-causes the signal 2 tobe cleared, but 'when the relay SR is energized withnegative potential, it causes the signal :2 tobe held at stop,

operated to a proper position.

This control-has merely been indicated in order to simplify the disclosure.

It willbe reiterated here, that the polar contact I04 of'relay GR is sufiiciently quick acting, so that the relay SR or SlVlR may not be operated before the control relay CR itself has been It will also be noted, that both the relays SR-and SMR are sufliciently quick acting to operate after therelay CR has been operated during either a total channel time of the normal rate, or duringa total channel time including a hesitation time period. These relays SR and SMR are of the permanent magnetic stick type so that their contacts remain in their last actuated positions although the current which controls them is only momentarily applied to their operating windings. Thus, the switch machine and signals are maintained in accordance with the positions of the control levers.

'With a system arranged in accordance with the above described organization, it is readily apparent that a large number of channel circuits may be sequentially closed by step-by-step means synchronously operated at a central oflice and at a large number of way stations. Also,ythat each of these channel circuits may be rendered available to carry out any one of four distinctive purposes. More specifically, these distinctive conditio'ns which may be set up over a channel circuit include a short positive impulse, a long positive impulse, a short negative impulse, and a long negative impulse. These distinctive conditions are respectively set up by the lever L -in a lowered position, by the lever L in a raised position, by the lever L in alowered position, and by the lever L in a raised position. Such an arrangement provides that a given number of steps taken by a step-by-step means at a central ofi'ice and at a large number of field stations will provide a greater number of distinctive controls than would ordinarily be provided by a system having such a number of steps.

Having thus shown and described one particular embodiment of the present invention and having shown specific arrangements for carrying out the various functions of the present invention,

particularly the functions of operatinga large number of selective control devices over a single channel circuit of a synchronous selector system, it is desired to be understood that the particular system selected has been selected for the purpose of facilitating disclosure of the nature and op erating characteristics of the present invention, and has not been selected for the purpose of disclosing its scope or the exact structure preferably employed in practicing the same, and that various changes, modifications and additions may be made to adapt the invention to the particular problem encountered in practicing the same, all without departing from the spirit or scope of the invention, except as demanded by the scope of the following claims.

What I claim as new is:

"1. A train dispatching system comprising, a dispatchers ofiice, a distant way station, a synchronous selector at said dispatchers 'office, another synchronous selector at said way station, means for operating the two mentioned synchronous selectors insynchronism, a'plurality of message circuits each including the same "line 'Wire and closed sequentially during operation of said selectors, a polar control relay in a particw lar one of said message circuits energized in response to the polarity of current flowing. in said message circuit, and a supplemental control relay of the permanent magnet stick type controlled in accordance with the period of time said polar control relay is energized.

2. A train dispatching system comprising, a dispatchers ofiice, a distant way station, a synchronous selector at said dispatchers oflice, another synchronous selector at said way station,

means for operating the two mentioned synchronous selectors in synchronism, a plurality of message circuits each including the same line wires and closed sequentially during operation of said selectors, a polar control relay included in a particular message circuit energized in response to the polarity of current flowing in said message circuit, and two supplemental control relays controlled in accordance with the position assumed by said polar relay and the time period through which said particular message circuit is energized.

3. A train dispatching system of the selector type comprising, a single pair of line Wires connecting a centralofiice and a plurality of field stations, means for transmitting from said central ofiiceto saidfield stations a series of impulses each impulse of which may be of any one of four distinctive characters, control means at said field stations distinctively responsive to said impulses, step-by-step mechanism at said ofiice and at each of said field stations for steering said impulses from the proper transmitting means to the proper control means, and traffic controlling devices controlled by said control means.

4. A train dispatching system of the selector type comprising; a single pair of line wires connectinga central office and a plurality of field stations; means for transmitting from said central oflice to said field stations a series of impulses each impulse of which may be either a short impulse of positive polarity, a long impulse of positive polarity, a short impulse of negative polarity or a long impulse of negativeipolarity, step-bystep means at said oiiice for controlling said transmitting means and step-by-step means at each of said stations each operated one step for each impulse irrespective of its character, control means at each of said field stations selected by said step-by-step means and responding distinctively to certain of said impulses; and trafiic controlling devices controlled by said control means.

5. A train dispatching system of the selector type comprising; a single pair of line wires connecting a central office and a plurality of field stations; step-by-step means at the ofiice and at each field station to define impulse periods, means controlled by said step-by-step means for transmitting from said central ofiice to said field stations a series of impulses, one impulse during each impulse period, each impulse of which may be either a short impulse of positive polarity, a long impulse of positive polarity, a short impulse of negative polarity or a long impulse of negative polarity; control means at each of said field stations controlled by the step-by-step means at such station and responding distinctively to said impulses and which may assume any one of four different conditions depending on the character of a particular impulse; and traflic controlling devices at each of said field stations controlled by the said control means at such field station. '70

6. In combination, a control office, a plurality of field stations, a line circuit connecting said control office and said field stations, step-by-step means at said control office and at each of said field stations all operated synchronously stepby-step through cycles of operation, means at the control office 'for selectively applying impulses of positive and/ or negative character to said line circuit for certain of said steps of said step-by-step means, and means at said field stations for selectively closing one or the other of two local channel circuits for each of said certain steps of said step-by-step means depending upon the polarity characteristics of the impulses of said line circuit for those steps, said local channel circuits being controlled by said step-by-step means and being closed only when said step-by-step means is operated tothe corresponding step.

7. In combination, a control ofiice, a plurality of field stations, a line circuit connecting said control oflice and said field stations, step-by-step means at said control oflice and at each of said field stations all operated synchronously through cycles of operation, means at the control office for selectively applying impulses of positive'and/or negative character to said line circuit for certain means at said field stations responsive to the polarity of the impulses on said line circuit for each of said steps to determine which one of said two channel circuits for that step shall be used.

8. In combination, a control office, a plurality of field stations, a line circuit connecting said control ofiioe and said field stations, step-by-step means at said'control ofiice and at each of said field stations, means for causing all of said stepby-step means to operate synchronously step-bystep through cycles of operation, means at said control ofiice for selectively determining the time said step-by-step means remain on certain steps of a cycle of operation, means at the control oifice for applying impulses of selected polarity to said line circuit for certain of said steps, two local channel circuits for each of said steps of said step-by-step means at said field stations, means at said field stations responsive to the polarity of the impulse on said line circuit for each of said steps to determine which one of two channel circuits for that step shall be used, and means distinctively energizing each of said selected channel circuits in accordance with the selected in channel circuits prepared by said step-by-step means, one for each of certain steps of said stepby-step means; means for dividing each of said channel circuits 'into a plurality of branches; and remotely controlled means controlled in accordance with the polarity of an impulse for selecting for use during any particular cycle of operation only a particular branch of each of said channel circuits.

10. In combination, a step-by-step means operable through a particular series of steps for any number of cycles of operation, a channel circuit prepared on a particular step by said stepby-stepmeans, remotely controlled means controlled in accordance with the character of a current impulse for dividing said channel circuit into a plurality of branches onlyone of which can be selected for use during any particular operating cycle, and remotely controlled means for distinctively energizing the selected each of the field stations all operated synchronously step-by-step through cycles of operation, means at the control ofiice for selectively impressing impulses of positive and negative character on said line circuit for certain steps of the step-by-step means at the office, means. at the control office for selectively determining the long and/or short duration of said certain steps of said step-by-step means, and means at each of said field stations selectively controlled by the impulses on said stepping circuit, means. at the control oifice for transmitting distinctive impulses over said message circuit on said steps, timing means at said field stations distinctively responsive tosaid prolonged impulses, message receiving means at said field stations responsive to said distinctive impulses on said message circult, and means at each field station jointly controlled by said timing means and said message receiving means at such field station.

13. In a centralized railway trafiic controlling system of the multiple impulse type for transmitting distinctive electrical impulses over a line circuit connecting two spaced stations, the combination with a line circuit, means for causing a series of impulses of current to flow in said line circuit which are distinctive both as to pclarity and duration, means distinctively responsive to the polarity of a particular impulse of said series of current impulses, slow-acting means distinctively responsive to the duration of said particular impulse of current and operated to one position for a particular impulse if the impulse is of long duration and which remains in its normal position if said impulse is of short duration, a polar relay, and a control circuit for said polar relay energized only by current of one polarity when said slow acting means is in one position and energized only by current of the reverse polarity when said slow acting means assumes the other position.

14. In a centralized trafiic controlling system for railroads, a central office and a plurality of field stations, a line circuit connecting said oifice and field station, control contacts in said oflice, electro-responsive devices at each field station, step by-step means at said office and at each field station for synchronously connecting control contacts and electro-responsive devices to said line circuit and controlled by impulses on said line circuit irrespective of their polarity or duration, said control contacts applying to said line circuit impulses of distinctivepolarities and distinctive durations, one of said electro-responsive devices being distinctively controlled in accordance with the polarity of a particular impulse and another electro-responsive device being distinctively controlled in accordance with the duration of such impulse, and traflic controlling apparatus controlled by said one and said another electro-responsive devices.

15. In a centralized traffic controlling system for railroads, a central office and a plurality of field stations, a line circuit connecting said office and field station, control contacts in said ofilce, electro-responsive devices at .each field station, step-by-step means at said oifice and at each field station for synchronously connecting control contacts and electro-responsive devices to said line circuit irrespective of their polarity or duration, said control contacts applying to'said line circuit impulses of distinctive polarities and distinctive durations, one of said electro-responsive devices being distinctively controlled in accordance with the polarity of a particular impulse and another electro-responsive device being distinctively controlled in accordance with the duration of such impulse, a switch controlled by said one electro+responsive device, and signals controlled by said another electro-responsive device.

.said line circuit and controlled by impulses on RICHARD C. LEAKE. m

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