US2042668A - Train dispatching system for railroads - Google Patents

Description

June 2, 193e.

R. C. LEAKE yTRAIN DISPATGHING SYSTEM FOR RAILROADS Filed- NOV. 22, 1928 3 Sheets-Sheet l um mrx Y Qdi June 2, 1936.

R. C. LEAKE TRAIN DISPATCHING SYSTEM FOR RAILROADS FIG. 1B.

Filed NOV. 22, 1928 5 Shets-Sheet 2 www m June 2? 1936 R. c. LEAKE TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed Nov.422, 1928 3 Sheets-Sheet 3 ATTORNE Patented .une 2, 1936 UNITED STATES TRAIN DIsPATcl-TING SYSTEMv FOR RAiLRoAns Richard C. Leake, Rochester, N. Y., assigner to General'Railway Signal Company, Rochester,

Application November 22, 1928, Serial No. 321,186

16 Claims.

This invention relates to a train dispatching system of the type in which theV dispatcher can control distant switch machines and in which trains are dispatched by wayside Vsignal indications, and in which the control over the signals and switch machines and indications of train progress are transmitted over a comparatively few wires, by apparatus of the synchronous selector type. v

In order that a dispatcher may properly dispatch the movement of trains, he should from time to time be informed as to the progress of trains along the track. This indication of train progress is known in signal parlance as OS-ing train movements. It is understood by those skilled in railway practice that OS indications may come in simultaneously and in closelylspaced overlapped relation, and for this reason a synchronous selector type system for transmitting such OS information lends itself to this function admirably, this because a synchronous selector system of the type hereinafter described permits the transmission of a very large number of distinctive indications over the same line wire in a very short period of time.

In accordance with the present invention, it is proposed to use a synchronous selector system in which a continuously operated distributor is located in the dispatchers office and in which each way station along the railway track is equipped with a synchronous distributor, which, when required, is operated in synchonism with the selector in the dispatchers cnice. In accordance with the present invention, if an OS signalis to be transmitted from a way station to the dispatchers oflice, only the synchronousrdistributor at that way station is operated in synchronism with the selector, but when a particular signal or switch machine is to be controlled by the dispatcher each one of the way station distributors is operated. By this arrangement` the way station distributors will be at rest a large part of station distributors shall be operated during the next following series of impulses, or Whether the way station distributors shall-remain aty rest, each subject to initiation from the wayV station at which 'it is located. Other features ofY the present invention reside in the construction and arrangement of parts to establish synchronism between the various way station distributors with the dispatchers selector, includingmeans for stepping a way station distributor additional steps in the 5 event it has not completed its entire cycle of operation.

Other objects, purposes and characteristic features of the present invention will in part be v obvious from the drawings and in part be pointedV l0 out in the following specication.

In describing the invention in detail reference will be made to the accompanying drawingsin A which Fig. 1A illustrates the equipment in the dispatchers oflice;

Fig. 1B illustrates conventionally one embodiment of the track way apparatus located at a particular way station;

Fig. 2 shows on an enlarged scale a suitable mechanical stick mechanism for maintaining a contact closed for a predetermined number of revolutions of a selector contact.

Fig. 3 shows the control and indication circuit of the system shown in Figs. 1A and 1B; and

Fig. 4 shows a modied control and indicationv circuit arrangement in which alternating current is superimposed upon direct current to obtain a larger number of indications through a limited number of control channels. 30

From the foregoing it is readily understood that'the apparatus includes two rather distinct mechanisms and circuits, as followsz-(l) A stepping or synchronizing circuit and mechanism, which keeps the rotating selector contact and the rotating distributor contact at each way station in exact synchronism, and includes mechanism for normally holding all of the distributors at rest, but allows a wayV station distributor to' Y start when an OS is to be transmitted from such 40 station and allows all ofthe way station distributors to operate in synchronism with the dispatchers selector when the dispatcher operates a lever to control a distinct function, and (2) control and indication circuits and mechanism, 45

verging routes', it has, for convenience, been 55 Yated bythe spring 26.

shown applied only to a passing siding PS connecting two single track sections and N and O of a single track railway system signalled with wayside absolute-permissive-block signalling.

In the particular arrangement shown the east end Vof passing siding PS is provided with entering signals I and Id and starting signals 2 and 2d, and the west end of the passing siding includes entering signals 8 and 8d and starting signals 1 and 1d. At the east end of the passing siding PS is a track switch SE, operated by a switch machine SME, whereas the Westend ottl'iispass,--` ing siding has associated therewith a tra'ckswitcli- SW operated by a switch machine SMW. EachL of these track switches have the usual,"detectorl track circuit associated therewith,; the `eastfend detector track circuit includes the usual track battery and a track relay,- designated DE, and the detector track relay at the'west'eind of the passing siding PS is designated DW.. These` Switch machines and signals are controlled from a dispatchers oflice, and the detector track relay transmits OS signals to the dispatchers oflice through suitable synchronously controlled mechanism, Vof which the distributor mechanism at the east end of passing siding PS has been designated SDE, and the distributor apparatus at the Westend lof this passing Ysiding has` been shown schematically and designated SDW, and of which the synchronous selector mechanism located in the dispatchers oflice, and shown in Fig. 1A of the drawings, has been designated SS.

In the dispatchers Voflice has been shown a miniature passing siding ps to represent the pass-V ing siding PS shownin Fig.l 1B, indicating lamps IW and IE being shown and connected in the system to be illuminated when theV detector track relays DW and DE are de-energized, respectively.

Atrthe east end of passing siding PS are provided three control relays SMR, SR and DR for controllingy the switch machine, the signal to proceed or stop andthe direction of traic respectively. Each of these relays is one of the permanent magnet stick polar type, which if momentarily energized by current of one polarity is operated to a particular position andl remains in that position byV magnetic iiuX from a permanent magnet until energized by current of the opposite polarity. The manner in which these relays control the switch machine and signals will be pointed out hereinafter.

The synchronous distributor mechanism for each of the various way stations is the same and for convenience the mechanism for the east end of passing siding PS only will be described. This mechanism comprises a distributor contact I0,

which when rotated is adapted toV co-operate with-a stationary contact II, a slipring I2 and.

stationary lcontacts d0, d1, d2, d3, etc., to d2". This distributor contact I8 may be rotated in any suitable manner, but in the particular arrangement shown is rotated by a suitable electrically operated spring-driven escapement mechanism including a pallet I5, escapement wheel I6, electromagnet I1, co-operating with a permanent magnet I8 to reciprocatethe pallet I5, the escapementwheel I6 being driven through suitable reduction gearing I9-2iland operated by a main spring 2 I, which main spring is Wound upthrough the medium of ratchet Wheel 22. The ratchet Wheel 22 is held in its Wound-,up position bypawl 23, and is operated to wind up the main spring 2| through the mediumof arm 24 Aand pawl 25 actu- This spring26 being elongated intermittently throughV the medium of pinion 21 and sector 28 operated by the armature 29 of the winding magnet WM. It is thus seen that the main spring 2| can only be Wound up to a tension corresponding to that of spring 26, the spring 26 being only tensionable to an extent where arm 24 strikes the stop 30 and therefore has substantially a fixed tension. The distributor contact ID is normally held at rest by the stop arm 3| held against the fixed stop 32 by the spring 33, this stop arm 3l being released 1 upon energization of the trip magnet TM. 'Ihe distributor mechanism SDE also includes a quickacting line relay LR, a medium-slow starting relay STR and a very slow blank repeating relay BR." l The, synchronous.- selector mechanism in the dispatchers cnice-includes a selector contact 40, rotated by a Worm.,gear,4I, driven by a worm 42, connected on the shaft 65 of a chopper including commutator segments 43, 44, 45, 46, 41, 48, 49, 2 and 50, of which the segments 49 and 50 are connected to slipy rings 5I and 52 respectively, these slip rings being connected to opposite terminals of a suitable battery 53. This chopper, or commutating mechanism, is driven by a motor M, Aand 2 also includes stationary brushes 53', 54, 55, 56, 51, 58, 59, 60, 6I, and 62. Although the number of revolutions of the chopper per each revolution of the selecting contact 40 may be of any suitable ratio, for the purpose of facilitating description 3 Yof the particular embodiment of the invention shown a gear ratio, between the chopper shaft 65 and the selector shaft 66, of I8 to I has been selected, or in other wordsthe worm gear 4I has I8 teeth. Suitable mechanism is required. for 3 closing the synchronizing circuit for a particular number of impulses only, from which it appears that the point of making and breaking the synchronizing circuit to obtain such number of impulses must be very accurately determined, for 4 which the cam operated contacts 61, 68, 69, and 1D and the mechanical stick contact 1I, operated respectively by the cams 12, 13, 14, and 15 and the magnet 16, are provided. The functioning, of this apparatus is more readily described in con,- 4 nection with the operation f the stepping or synchronizing mechanism. The selector contact 40 co-operates with stationary contacts s0, s1, s2, etc., to contact s2".

In the dispatchers oice are also provided 5 levers LSME and LDE for controlling the switch machine relay SMR and the relays SR-DR respectively, similar levers LSMW and LDW being provided to control similar relays (not shown) at the west end of passing siding PS. There are also 5 provided indicating relays WR Aand ER for controlling the illumination of indicating lamps IW and IE, respectively, in response to deenergization Vof detector relays YDW and DE, respectively. The functioning of this apparatus is more readily described hereinafter under the heading, Operation of Control andvIndication Mechanism.

Operation of stepping and synchronizing 'mech-r anism.-As already. stated the selector contact 40 is continuously vdriv'errbyy the motor M and rotates one complete revolution for each 18 revolutions of the motor. This selector mechanism SS inthe dispatchers oice as shown in the drawings -is assuming a position of blank, in which the stepping circuit including the synchronizing wire is open at contacts 69 or.10. Upon a. few additional y rotations ofthe motor M, however, theV cams 14 and v15 assumek a position to close contacts 69 ari/6.10. The closure of contact 10 is immaterial 75 Cil since the circ'uit invwhich it is included is open attheContact'||,'...'v H

Closure of the contact 69 occurs at the beginning of a positive wave of current flow in the stepping circuit, as determined by the commutator 49-50, and continued operation thereafter causes this plus impulse to be followed by successive minus and plus impulses. This stepping circuit may be traced as followsz-beginning at the plus terminal of battery 53, wire 80, brush 62, ring 52, segment 50, brush 60, wires 8| and 82, cam contact 69, wire 83, cam contact 61, wire 84, synchronizing wire 85, wire 86, line relay LR, wires 81 and 88, common return wire C, wire 89, brush 59, commutator segment 49, ring 5|, brush 6|, wire 90 back to the negative terminal of the battery 53. Continued operation of the selector mechanism SS causes 16 cycles, namely, a series of 16 positive and 16 negative impulses to be transmitted to the line relay LR. The rst or positive impulse will cause operation of the line relay LR to the dotted position and had the last impulse of the previous series of impulses been a positive impulse it would have allowed the line relay LR to remain in its then dotted line positon. After these |6 cycles of alternate impulses have been transmitted to the line relay LR, the contact 61 will be abruptly opened thus breaking the stepping circuit strictly at the end of a negative impulse, and during the next two revolutions of the motor M, bearing in mind that the worm wheel 4| has 18 teeth, although the contact 61 will close in the meantime, will leave the stepping circuit open at the contact 69, after which the stepping circuit is again very quickly completed at the beginning of a positive impulse and remains completed for |6 alternate, positive and negative impulses, it being noted that the contact 61 is abruptly opened and the Contact 69 is abruptly closed, this is done so as to both make and break the circuit very quickly at the end of an impulse.

The line relay LR in response to the impulses just mentioned will apply current owing in one direction and then the other to the co-il on the pallet I5 of the escapement. Operation of this escapement pallet l5, however, at this time does not cause rotation of the distributor contact I0, because the distributor shaft 9| is held stationary by the stop arm 92 engaging the trip arms'3 It should be noted that the pole changer contacts 95 and 96 of the line relay LR apply alternating positive, and negative, impulses to the period-of -blank relay or blank repeating relay BR. This relay BR is a slow-acting relay and will not respond to the alternate positive and negative impulses, but will respond during the period of blank extending through two complete revolutions of the motor M for reasons heretofore explained, so that the relay BR is energized during the 17th and 18th revolution of the motor M of a complete cycle of operation of the selector contact 40. Energization of the blank repeating relay BR closes the following circuit for rewinding the main spring 2| of the clockdriven escapementbeginning at the battery |00, wires |0|, and |02, Contact |03 of the blank relay BR, wire |04, winding magnet WM, wires |05 and |06, back to the negative side of the battery |00. With the winding magnet WM energize-d the armature is attracted to tension spring 26, and if the tension of spring 26 exceeds that ofv main spring 2| the escapement mechanism is rewound, thus keeping the tension of the main spring constant.A` It is thus seen that normally the line relay LR will be caused to be oscillated for a period of |6 revolutions of the motor M and will then leave the relay LR at rest in its le-ft hand position for the last two revolutions of this motor, and that this functioning of the line relay LR will cause the blank repeater relay BR to remain in its deenergized position during 16 revolutions, and will cause it to assume the energized position during the next two revolutions. For reasons which will appear hereinafter the distributor contact |0 is not rotated under the conditions assumed.

Let us now assume that the detector track relay DE at the east end of the passing siding PS is de-energized. Under this condition of relay DE the following circuit for energizing the starting relay STR is completedr-beginning at the battery |00, wires |0|, and |01, front contact |08 of the blank relay BR, wires |09 and ||0, distributor contact I0, wires and ||2, winding of the starting relay STR, wire I3, back contact of the detector track relay DE, wires |5 and |06 to the negative terminal of the battery |00. With this circuit completed the starting relay STR after a short period of relay assumes its energized position, this relay being slightly slowacting, and effects clo-sure of stick contact 4, thereby completing a stick circuit for this relay which is the same as the pick-up circuit, just traced, except that the distributor contact l0 is shunted by stick contact |4. With the line relay LR in the left hand position and with the relays BR and STR energized the following circuit for the trip magnet TM is completedt-beginning at the battery |00, wire ||6, polar contact in its left-hand position, wires ||8, ||9, and |20, winding of the trip magnet TM, wire |2|, resistance unit |22, front contact |23 ofthe starting relay STR, wires |24 and |25, contact 96 of the relay LR, wire |25 back to the negative terminal of the battery |00.

With this circuit completed the armature 3| is attracted away from the stop arm 92 against the tension of the spring 33, thereby allowing the escapement wheel I6 to move only a very short distance where it is held by the escapement pallet, the distributor contact |0 remaining on the stationary contact d0. As the motor M in the dispatchers oflice continues to operate, the contact 69 is again closed at the beginning of a positive impulse, thereby transmitting alternate positive and negative impulses to the line relay LR. Since the distributor contact |0 is rotated step by step in synchronism with the selector Contact 40 in the dispatchers oiilce, these contacts 40 and |0 simultaneously engage contacts s1, s2, s3, etc. and contacts d1, d2, d3, etc., respectively. It is thus seen that various circuits connecting various devices in the tower and at the way station are completed momentarily in succession.

When the distributor contact I0 has made a complete revolution it is again stopped by the stop arm 92 engaging the armature 3|, but since the detector track relay DE is still cle-energized, as assumed, the trip magnet TM is again energized during the period of blank, and the distributor contact |0 is again rotated during the next series of impulses. This will continue until the detector track relay DE is again picked up, after which the distributor arm I0 will remain at rest, unless the dispatcher operates a lever It has been pointed out -that series of impulses ing a total of thirty-two impulses.

are transmitted from the dispatchers'oice'over the stepping circuit to the various line relays, and that normally' each series comprises sixteen-cycles of alternate positive and negative impulses mak- Y Since the iirst impulse has been assumed to befa positive impulse the last impulse will be a negative impulse. Also it will be noted that the worm gear 4| has eighteen teeth which would afford eno-ugh time to transmit eighteen cycles, but as already mentioned there is a period of blank corresponding to twor cycles. Further, it is noted that only fourteen cycles or twenty-eight impulses are necessary to step the distributor contacts |0 at the various way stations entirely aroun-d and that sixteen cycles or thirty-two impulses are actually transmitted, from which it appears that two of these cycles-oi` four impulses are ordinarily not used. The eXtra two cycles or four impulses may for convenience be called synchronizing impulses, and serve to complete the revolutions o-f a way station distributor in the event it has lost one or a few steps for some reason or another. Under certain conditions, as pointed out hereinafter, there will be transmitted iive additional impulses thus making the last impulse a positive impulse. Y

Let us now assume that the dispatcheroperates one of the levers, such as lever LSME, for instance, and in so doing momentarily completes the following circuit:-beginning at the battery |30, wire |3|, lever contact |32 closed momentarily, wire |33, coil 16 of the mechanical stick device SD, Wire |34 back to the battery |30.

' Momentary energization of the coil 16 attracts theY armature 1|, thereby causing the arm |35, held against the stop arm |36 by the spring |31, to drop off of the rest |38 and engage the Worm |30, and thereby mechanically holds the armature 1| in its attracted position. The armature 1| will then remain closed through about five revolutions o`f the selector arm 40at which time the pin |40 projecting from the shaft 66 lifts the arm back on top of the rest |38, thereby allowing the spring |31 to return this arm to its normal position against the stop |36, and allowing the armature 1| to be retracted by the spring Ml. It is thus noted that a circuit including the armature 1| is closed at that point during ve revolutions of the selector arm With this armature 1| closed a multiple or branch circuit is completed bridging the contacts 61 and 69, which branch circuit includes the con'- tacts 68, 10, and 1|. It will be noted that the cams 11i and 15 are identical, so that the series of impulses are started at the same time irrespective of which of these two circuits are active. On the other hand, it should be noted'that cam 12 has its Contact closed only` during the period lof 16r complete cycles or 32 impulses, whereas the cam 13 has its contact closed through 161/2 cycles or 33 impulses, so that with the contact 1| closed, a series of impulses is transmitted to the distant way stations of which series the last impulse is a positive impulse, and therefore leaves the line relay LR in its right-hand dotted position during the period of blank. Y

With the line relay LR in its right-hand dotted position, and with the distributor contact I0 in its locked position, the following circuit for the starting relay STR is completed upon picking up ofthe blank relay BR:-beginning at the battery |00; Wires |0| and |01, contact |08, wires |09 Yand ||0, distributor Contact I0, wires and ||2.,.winding. of the starting relay S'IR,.Wire ||3,

ing relay STR lenergizedand stuck up by its stickV Contact ||4 the trip-'magnet TM'ls energized through the; circuit heretofore traced, thereby,

pickingup the trip arm 3|. With the triparm 3| in its raised ,position the stop,` arm 02 is released, and since the escapement wheel can turn through an arc of substantially one-half tooth before the left-hand anvil of pallet l5 is engaged; the distributor arm is moved tothe position d1; As the next series of impulses is transmitted from the dispatchers ofiice, the rst impulse of which will be a positive impulse, the distributor arm l0 will not'be changed during this first impulse, because it has already taken a step correspending to: this positive impulse, the first negative impulse; however, will start the distributor arm 0 stepping, andcausegthis arm to be stepped in synchronism with the selector arm 40 over the successive contacts. In the manner just described, the distributor'arms |0 of all of the various Way station distributor mechanisms will be rotated in synchronismwithl the selector arm 404 through ve revolutions due to the transmission of ve successive series of impulses, after which the stick device SD will open-its contact 1|, afterwhich the last impulse of each' series will again be a negative impulse,- thus leaving the various way station devices at rest thereafter, until either a detector track relay is dropped or the dispatcher again operatesa lever.

It is thus seen that the selector mechanism ln the dispatchers oice is operated continuously, all the way station distributor mechanisms are operated through five revolutions each time the dispatcher operates a lever, and that upon Ythe necessity of transmitting an OS indication from a way station to the dispatchers office, the distributor at thatway stationis operated so long as the OS-ing condition persists. Instead of operating the entire system through five revolutions lfor each lever movement, it may be operated a less number of revolutions, all that is required is that it operate at least one complete revolution.

Operation of Control and Indication M echanism-Let usassume that there is an east bound train on the main track of passing siding PS, and

that the dispatcher wishes it to proceed into then single track section O. In order to do so he Will move the lever LDE to the right-hand position thereby, for reasons heretofore given, causing the distributor arm I0 to be rotated in synchronism with the selector arm 40, and momentarily transmitting a positive impulse to the direction relay DR, whichimpulse would operate this directionv relay to the right-hand position did it not already assume this position. This circuit may be traced as followsz-beginning at the. positive side of the battery |50, in the dispatchers oice, through certain wires and devices as folloWs:-|5|, 51, 41, 48, 58, |52, |53, lever Contact LDE, |54, S6, selector arm 40, selecting wire |55, |56, |51, winding of the direction relay DR, |58, Contact d6, distributor arm I0, ring |2, wires |59, 88, common return wire C, 89, |6|, devices 56, 46, 45, 55, Wire |62, back to the middle point of battery |50. Since the direction relay DR already assumed its righthandposition the position of this relay is notchanged. Also, with the lever LDE in the righthand position a circuit is completed for operating the signalrelay SR to the right-hand position as followsz-beginning at the ,positive side of bat-v tery |50, throughcertain Wires and. devicesas -in its right-hand position, I 64, selector contact, s", selector contact 40, selecting wire |55, |56, |51,

" to the middle point of battery |50.

|65, winding of the signal relay SR, |66, distributor contact d", distributor arm I0, ring I2, |59, 88,

common return wire C, 89, I6I, 56, 46, 45, 55, |62,

The momentary impulse transmitted to the signal relay SR, through thecircuit just traced, operates the polar relay SR to its right-hand position where it is held by its permanent magnet until it has been energized by-current of negative polarity. With the signal relay SR and the direction relay DR both assuming the righthand position, and with the switch machine in the main track position the signal 2 is operated to the clear position, providing traiiic Conditions in advance are clear, through a circuit readily traced in the drawings.

Similarly if the lever LDE is operated to the lefthand position the direction relay DR is operated to the left-hand position but the signal relay SR is operated to the right-hand position, in which event, assuming the track switch to assume the main track position, the entering signal I may be cleared, if traic conditions in advance are clear,

, through a circuit readily traced in the drawings.

Let us now assume that there is a west bound train travelling in the single track section O, and

that the dispatcher wishes to allow this train to move on the side track of the passing siding PS. In order to do so, it will be necessary for him to first operate the track switch SE to the takesiding position, and to accomplish this the dispatcher will move the lever LSME to the lefthand position. Movement of lever LSME to the left-hand position will through the medium of contact |32 associated therewith operate the stick device SD 'to cause all of the way station distributors to operate through 5 successive revolutions of the selector arm 40. Movement of the lever LSME to the left-hand position closes the following momentary circuitz-beginning at the negative terminal of the battery |50, through certain wires and devices as follows:-|10, 53, 43, 44, 54, |1I, contact LSME in the left-hand position, wire |12, selector contact sa, selector arm 40, selecting wire |55, |56, |51, |65, |83, winding of the switch machine relay SMR, wire I 84 distributor contact d8, distributor arm I 0, ring I 2, |59, common return wire C, 89, I6|, devices 56, 46, 45,

55, wire |62 to the middle point of battery I 50. Completion of this circuit will transmit a momentary negative impulse to the switch machine relay SMR, thereby causing its contact to assume the left-hand dotted position in which it remains until it has been momentarily-energized by current of the opposite polarity.

With the switch machine relay SMR in its lefthand position the switch machine SME is operated to the. take-siding position only in the event all of the signals associated therewith are at stop,

and providing there is no train approaching, as determined by suitable approach locking means vmore specifically disclosed in the application of S. N. Wight, Sel. N0. 120,423 led July 3, 1926.

Id is moved to the proceed position, bearing in mind that the switch machine SME now assumes the take-siding position, in which case the contacts |16 and |11.assume the dotted position.

As the west bound train in the single track 5 section O accepts the'take-siding signal Id, and in so doing treads upon the detector track circuit and de-energizes the detector track relay DE the distributor SDE is operated in synchronism for reasons heretofore given and an impulse is transl0 mitted to the indicating relay ER in the dispatchers office over the following circuitz-starting at the battery |80, wire I 8| back contact |82 of the detector track relay DE, wire |83, distributor con-- tact 19, distributor arm I0, wires |59, 88, -coml5 mon return wire C, |84, |85, winding of the indicating relay ER, |86, selector contact S9, selector arm 40, selecting wire |55, wire |56, back to the opposite terminal of the battery |80. The momentary completion of the circuit just traced energizes the indicating relay ER, thereby 'illuminating lamp IE and informing the dispatcher that the train in question has accepted the takesiding signal I d. The indicating relay ER is preferably slow-acting so that it will remain energized during a complete revolution of the distributor contact I0, and since the circuit just' traced is completed momentarily during each revolution of the distributor contact I0, and since this distributor will remain in operation so long as the detector relay DE is de-energized'the indicating lamp IE will be illuminated so long as the detector track relay DE is de-energized.

As soon as the detector relay DE is again energized the indicating relay ER is de-energized and the lamp IE is extinguished. If vthe dispatcher, after having cleared the take-siding signal Id, wishes to again put that signal to stop he will return his lever LDE to the middle position, in which case the magnet 16 is again 340 energized, dropping the arm |35 into the worm |39 and causing the wayside selectors to operate through Vvecycles, and causing current of negative polarity to be momentarily applied to the signal relay SR during 5 successive revolutions of the distributor contact I0, thus operating the signal relay SR to its left-hand position and. breaking 'the energizing circuit for the signal Id.

Operation ofthe system.-From the foregoing it readily appears that the operator may fhold all of the signals at one end of a passing'siding at stop or may clear any one of the signals, the selection of a particular signal being made through the direction relay DR andthe position of the switch `machine SME. For instance, 'if 55 the switch machine assumes the main track position, the direction relay DR when -it assumes the right-hand position will'select east bound traflic and clear signal 2, but if this direction relay DR is in the left-hand position west bound trafc is selected and signal `I is cleared. On the other hand, if the switch machine SME is in the take-siding position, with the direction relay DR energized in the right-hand position east bound traic may move, thus clearing the dwarf signal 2d, but if this direction relay DR is in its lefthandposition, the take-sidirg signal Id may be cleared, such clearing of the signal in each case depending on the position of the signal relay SR.

In practicing this invention a dispatcher may control the signal and switch machine at the ends of any passing sidings, and the dispatcher is informed by indicating lamps associated with the miniature track layout, a portion only of which has been shown, in the 4dispatchers oiice of 75 fthe-entrance and departure of trains to the ends contacts.

contacts 2, 3, 4, and 5 on the selector in the dispatchers office andfcorresponding contacts on o'f: the various passing sidings. Attention is directed tothe fact that `the levers LSMW and LDW control the apparatus located at the west end of passing siding PS, the apparatus of which `is identical to that already described, and this :apparatus has been conventionally illustrated by` thev distributor contact IDW and its associated Attention is directed to the fact that the distributor' SDW'are used for controlling the apparatus at the-west end of passing siding PS.

"Itis-also to be understood that the various way station distributors' may be stepped around jby any suitable stepping mechanism, such as ratchet means instead of the escapement type of v.mechanism shown. VFurther, the. exact arrangements of circuitsand devices used for startringa particular way station selector when an OS Ysignal isto be transmitted from such way sta- `and 'DR are polarrelays of the permanent magnet stick type,V and the relays WR Vand ER are rneutral relays, neutral relays may be used at a vfway station and.l polar magnetic stick relays may be .used-in `the dispatchers office, or both types -of 'relaysmay be located at both, or either, of these locations. y

From the foregoing Adescription it isapparent if arrailway system is equipped with the apparatus described' toy each of its passing sidings, diverging `routes .and interlocked crossings that Ythe vdispatcher has absolute control over-all of the trains, .may cause a train to'take the main track or asider trackxof a .passingsiding, may cause .itito take a diverging route, may hold it at a cation.

Arailroad crossing, may hold a train yon a main track or a'side track of a passing siding, or put- 4ting `itxbrieiiy may definitely .control each train -on the zsystem.V Also, it is apparent that the control of trains is much facilitated in that the dispatcher is informed from time to time as to the 'progress yof trains, their speed and their lo- Modz'fied. `structure voj vFig. 4,-The 4system -shewn .inFigs 1A and-1B afford meansfor intermittently and in succession, connecting a plu- `ralityzof `circuit portions-at a dispatchers office with aa plurality of Vcircuit portions at various way stations, through` the imediu-m of a single ilinecircuit, so as toftransmit alarge number of :distinctive controls and iindications'over such line circuit. In :accordance with .the invention .fshown in Figs. lAvand'lB; these various controlsV and: indications are carried out by the flow of direct currentflowing in one direction or the other. zInfaccordance with the invention. shown inailig..4'of zthedrawings alternating current is Y .-superimposeden the momentarily completed direct current circuit, so that the number of indications over a single control channel is in- .-creased.

V-'In order'to simplify the description of the sys- Vtemff-,asshown in-Fig. l4, the stepping circuit and associated devices have vbeen omitted, and for this'reason' the omitted. features Aof Figs. 1A and AlBmustbe read into theffdrawing of Fig. 4 to ...make-a Acomplete system.

characters asin Figs..1A and l1B.

Iliurthenin'order to make it readily'apparent vwhat devices ymust ibe-added in' order tov vsuperimpose distinctive high frequency alternating vcurrents on the/.various'successively completed circuits shown in Figs.. lA'and 1B, a simple circuit arrangement has been shown in `Fig.l3 Vof the drawings illustrating the' switch machine relay SMR circuit of Figs. 1A and 1B, in which all of the parts havebeen given like reference tical with Fig..3 except for the apparatus necessary forsuperimposing alternating current upon direct current in accordance with the modified form of the invention.

Referring to Fig. 4 ofthe drawings it `will be noted that the directcurrent control circuitincluding the lever LSME and the switch machine Fig.V '4 is viden-v relay SMR in series has not been disturbed, orY

changed, except for' the fadditionof' the inductance 200 .inserted at the lever-end of 'the circuit and the inductance'ZOl inserted" at the relay endof the circuit, neither of which materially affect the iiow o'f direct. current therein. VInfaccordance with the particular embodimentofthe invention shown in Fig.l 4,. a high frequency `alternating current `is employedV for transmitting an OS indication from a wayrv station to the `dispatchers cnice. For this reason, 'a'double winding `alternating current relay ER1 is vemployed instead of a direct currentneutral relay ER, `andA this indication 'relayER1 repeats its indication to the repeater indication relay -RERklwhichinturn controls the indicating lamp'IE. These relays ER1 and RER1 are so interconnected with :the cam operated contact 203`as to cause the indicating lampIEl to be energized and remainV illuminated for at least one revolution ofr the rselector. rcontactll after the energization of relay `ER1,

as will be more clearly' described hereinafter.

In order to complete the high frequencyal- .ternating current circuit for OS-ing purposes the switch machine relayY SMR together with'its inductance 20| are shunted 'by a vback contactr of the detector track relay DE, .through'a partial circuit including a condenser'204. It is noted that.

the control of the switch machine `relayiSMRby direct current is not interfered with, even though the detector ltrack relay DE is de-energized, .because direct current cannot flow through the condenser 204. Similarly, with the `leverLSME in either its right or left-'hand extreme position, 'direct current! from the battery |50 cannot ow `through the superimposed parti'of the' circuit =be cause current from battery i150 cannot iiow through the superimposed `part of the circuit;

including the .high frequency generatorHC- and the upper winding /off thel indicating vrelay ERl, because this circuit includes. a condenser "205. Itis thus noted that the switch machine' SMRin the arrangement shown inFig.'4 may be Vcontrolled in identically the same way as itis controlled in Figs. 1A `and 1B and in Fig. 3.

Let us know consider the manner ini-Which the indicating lamp IE may be energized in response to dropping of the detector track relay- DE. Let us assume that a train is entering the right-hand end of passingV siding PS (not specificallyl shown in Fig. 4)'thereby closing the contact'206 of this relay, and dropping contacts H4 and |42' (not specifically-shown in Fig. 4) 'Although with contact 206 open a very small amountV of 'high'.'frequency alternating current may flow through the upper side of the indicating relay'ERl, this current is unable'to operate-this relay ER1 lbecause it is too small in value by reason of the inductance.

| included in the circuit. If'nowthe contact l 206 is closed, as has been assumed, the indicating relay ER,1 is picked up by reason of high frequency alternating current flow in the following circuit-beginning at the high frequency generator HC, wire 201, upper Winding of the indicating relay ERl, wire 208, condenser 205, Wires 209, and |12, distributor contact s3, selector arm 40, selecting wire |55, wires |56 and 2|0, back contact 200 of the detector track relay DE, wire 12| condenser 204, wire 2|2, distributor contact d8, distributor arm |0, ring I2, wire 59 and 88, to

the common return wire connected to the other side of generator AC.

With this circuit momentarily completed the indicating relay ER1 is momentarily energized by current in its upper winding, and in response to closure of its front contact completes the following direct current circuit through itslower windingz-beginning at the battery 2|5, wire 2|6, contacts 203, wire 2 |1, contact 2 |8, wire 2| 9, lower winding of the relay ER1, wire 220, upper winding of the repeater relay RERl, wires 22| and 222, back to the battery 2 5.

With this circuit completed the repeater relay is caused to assume its energized position in which the following stick circuit for this repeater relay RER,1 is completedz-beginning at the battery 2 |5, wire 2|6, cam operated contact 203, wire 223, contact 224, wire 225, lower winding of the relay RER1, wires 226 and 222, back to the battery 2|5. With the repeater relay REI?,1 energized its front contact 221 closes an energizing circuit for the indicating lamp IE.

The cam operated contact 203 is operated by the cam 230, which cam is contained on the shaft 66 and is operated at the same rate of speed as is the selector arm 40. Asis apparent from the drawing the cam 230 must make at least one complete revolution after energization of the relay ERl in order to extinguish the indicating lamp IE. Let us assume that the relay ERl and RERl are both energized, for reasons just explained, and that the cam 230 is operated in Y l the right-hand direction as is the selector arm 40. When the depressed part of the cam is engaged by the roller 232 the upper member of contact 203 is opened thereby breaking the circuit including the stick contact 224, but since the relay RERl is also energized by the current flowing through the lower winding of relay ER1, this relay RER.1 remains in its energized condition. After a small fraction of a revolution of the cam 230, the roller 232 is engaged by the cam portion 23|, thereby causing opening of the lower member of contact 203, and thereby breaking the stick circuit for lower winding of the relay ER1 and effecting de-energization of this relay ER1. The relay REB'.1 remains energized, however, because the circuit for its lower winding is still closed. After substantially another complete revolution of the cam 230 the upper member of contact 203 is again opened thereby effecting dropping of the relay RER1 and causing extinguishment of the lamp IE unless the relay ERl has been picked up in the meantime. It is thus noted that the indicating lamp IE will be illuminated for more than one complete revolution of the selector contact 40, so that this indicating lamp will give a continuing indication in response ito intermittent energization of the indicating relay ERl, which intermittent energization is repeated so long as the detector track relay DE remains de-' energized.

In accordance with the invention shown in Fig. 4 of the drawings, applicant has thus provided a system of the synchronous selector` type in which alternating current is superimposed upon direct current in order to increase the number of controls and indications communicatable over a single control channel. It is, of course, understood that the flow of direct current in the selecting circuit in response to operation of the lever LSME will not materially affect the flow of alternating current in the same selecting Wire and common return wire, in response to closure of the detector track relay contact 206. It is desired to be understood that other circuit arrangements may be employed for transmitting both alternating and direct current over momentarily completed synchronous selector circuits within the scope of the present invention. Also, it is desired to be understood that other devices, such for instance, as the mechanical stick device SD may be used, instead of the cam operated contact 203 co-operating with the repeater relay RER2, for maintaining the indicating lamp IE energized for at least one revolution after it has been illuminated.

Although two rather specific forms of the invention have been illustrated, in which specic Aapparatus has been shown and described for accomplishing specic functions, it is desired to be understood that manyother forms of this in- I vention, coming within the scope of the appended claims, may be used instead. For instance, other devices for closing the circuit through contacts 68 and 10 may be used instead of the mechanical stick device SD shown. Any number of contacts' may be used instead of the 28 contacts shown co-operating with the selector contact 40 and the distributor contact I0. As heretofore mentioned either thirty-two or thirty-three impulses are transmitted in a series depending upon whether the device SD is in its circuit closing position `or not, and from the structure it appears that only fourteen cycles, namely twenty-eight stepping impulses are necessary to step the distributor contact |0 entirely around the circumference.:

This leaves four or iive additional impulses transmitted after the distributor contact I0 is supposed to have completed-its revolution, depending upon whether thirty-two or thirty-three impulses have been transmitted. These additional imi pulses may for convenience be called clearing of synchronizing impulses, in that if the distributor contact |0 should have lost a positive and a negative step, and therefore is stepping two steps behind its theoretical position, this distributor f contact would be permitted to catch up, so to speak, and get back to its normal position ready for starting when the next series of impulses are transmitted. Similarly, any number of such clearing impulses may be transmitted at the end of the series, and the period of blank may be made as long as desired. Although the indicating relays ER and WR have been shown as slowdropping neutral relays, Vthese relays may be polar relays similar to relays SMR, SR, and DR, and may be operated to one position when the detector track relay is in its retracted position and be operated to the opposite position when the detector track relay is again energized, suitable means being provided to stop the way station distributor a short time after the track relay is again energized. Also, although in the particular apparatus shown only the de-energization of the detector track relay is manifested in the tower by suitable indicating lamps, if desired, the posiillustrated need not be adhered to, but that many tionl oflsignals,.theposition of the switch machines and the condition of occupancy of the track circuits may be indicated in the dispatchers oiiice in the same way.

It should be understood that the chopper, com- 'prising commutating segments t3-50, serves two important functions. In the iirst place it intermittently breaks the stepping circuit and also the message circuit by fast moving segments thus assuring that these circuits are made and broken rat precisely the correct time, and thereby avoiding sparking at the selector contact 40. Secondly, it should be no-ted that the stepping circuit is only closed whenv the message circuit is open,

'and Vice versa, and this assures that the flow ofV current in one of these circuits will not interfere with the proper functioning of the other circuit. Further it is to be understood that even though '.a battery |50 has been illustrated, an alternating current source having a frequency'of one cycle r per each revolution of the shaft 65 may be used,

it being understood that the voltage of the transformer would be in the proper direction during the communicating period. Also instead of applying the battery 53 to the stepping circuit by repeatedly reversing its terminals by devices as shown, an alternating current source may be used,either applied directly to the stepping cir- `cuit or applied intermittently as by placing a `chopper such as the commutator 41, 48, 51, and

58 in series with the alternating current source.

`Having thus shown, and described, several specific embodiments of a rather involved and V'comprehensive system, for carrying out certain functions, it is desired to be understood that the particular arrangement of devices and circuits changes, modications and additions may be made, in the individual devices as -Well as their vco-ordination with each other, without departing kfor transmitting successive positive and negative impulses to said way station distributors, and means for causing a particular Way station distributor to operate in synchronism with the dispatchers selector when an OS indication is to be transmitted from the particular Way station 'distributor to the dispatchers ofiice and for causing vall of the 'Way station distributors tooperate in .synchronism 'with the dispatcher selector when Vthe dispatcher operates a lever to control a vdistant traiiic controlling device.`

2. A synchronous selector train dispatching system for dispatching train movements by Wayside signal indications comprising, a dispatchers ofi 'ce, a Way station, means at s-aid dispatchers office for transmitting to lthe Way station either `an even or an odd number of .impulses oi which the first impulse is of a particular polarity, a synchronous distributor located at said Way station, and means causing the distributor to selectively operate in synchronism with said means.

3. A synchronousselector traindispatching system for dispatching train movements by wayside signal Vindications comprising, a dispatchers ofiice, a wayv station, means for repeatedly transmitting to the Way station a series of impulses of whichthe last impulse'may be apositive or negative impulse depending on conditions at said dispatchers oilice, said series of impulses being separated by a period of blank, and control means at the way station including a. polar relay operated in response to said impulses and in a direction corresponding to the polarity oi said impulses, and a slo-w-acting relay controlled by said polar relay constructed to assume its energized condition only during said period of blank.

4. A synchronous selector train dispatching system for dispatching train movements by wayside signal indications comprising, a Idispatchers oflice, a Way station, -apparatus inthe .dispatchers oilice for transmitting series of successive positive and negative impulses of which the last impulse may be a positive or a negative impulse depending upon conditions in the dispatchers cnice, the series being separated by a period of blank, a polar relay of the magnetic stick type responsive to said impulses and assuming a position depending upon the last impulsepreceding said period of blank, a slow-acting relay controlled by said polar relay and assuming -an energized position only during said period of blank, and a control circuitclosed only if said slow-actingv4 relay is energized vand said polar relay assumes a predetermined position.

' 5. A synchronous selector train dispatching system for dispatching train movements by wayside signal indications comprising, a dispatchers oiiice, a W-ay station, apparatus at said oliice for transmitting a series .of positive and .negative impulses to said way station vseparated by a period of blank, a polar line relay operated successively to-opposite positions'inaccord'ance with the polarity of lsaid impulses, a slow-acting relay controlled by said polar relay and assuming its energized condition only during said period of blank, step-by-step mechanism operated by said line relay, means for holding said step-bystep mechanism in the event said line relay assumes a particular position while said slow-acting relay assumes its energized condition.

6. Asynchronous selector train dispatching system forr dispatching train movements by wayside signal indications comprising, a dispatchers office, a way vstation at a distant point along a railway track, a selector in the dispatchers oflice for successively connecting a line Wire to afplurality of local circuits, adistributor contact'at a Way station for successively connecting said line wire to a plurality of' circuits local to said way station, means in the dispatchers oflice for transmitting successive positive and negative impulses to said way station distributor, and control means associated with said dispatcher selector for at times only causing said way stationgdistributor to operate in response to said impulses, and including a device for closing a circuit during a predetermined number of revolutions of ashaft and comprising in combination ashaft, a Worm'on said shaft, a device which if tripped from its normal condition will engage said worm at one end thereof, and means for restoring said device to its normal con-dition when said device has reached the other end of said worm.

'7. In a synchronous selector type train dispatching system operable through cycles of operation, an indication circuit only momentarily completed during a cycle of operation of the sys- CII tem, an indicating relay which is at times picked up during momentary completion of said indication circuit, a stick circuit for independently m-aintaining said indicating relay energized, a repeater relay having a pick-up winding included in said stick circuit, another stick circuit for said repeater relay, and means for alternately breaking the said two stick circuits.

8. In a synchronous selector vtype train dispatching system operable through cycles of operation, an indicating circuit only momentarily completed during a cycle of operation of the system, an indicating relay which is at times picked up during momentary completion of said indication circuit, a stick circuit for independently maintaining said indicating relay energized, a repeater relay having a pick-up winding included in said stick circuit, another stick circuit for said repeater relay, and means operated during a cycle of operation of the system for alternately breaking said two mentioned stick circuits following the momentary completion of said indicating circuit.

9. In a train dispatching system of the synchronous selector type, the combination with a distributor requiring a predetermined number of impulses from a pulsating source of current to operate the same and means for applying and disconnecting said pulsating source including two snap action cam operated contacts connected in series one of which closes the circuit gradually and opens it quickly and the other of which opens the circuit gradually and closes it quickly, said devices being so constructed that the gradually acting closing contact acts shortly before the quick acting closing contact and the gradually acting opening contact acts shortly after the quick acting opening contact.

10. In a synchronous selector train dispatching system, the combination with a local office and a plurality of way stations, of a plurality of message circuits each including the same line wire and common return wire, manually operable means for causing a cycle of operations during which cycle said message circuits are closed sequentially, automatic means vfor repeating said cycle of operation a predetermined number of times, and signals at each of said stations controlled over said message circuits.

11. In a centralized tramo controlling system for railroads, a control ofce, a plurality of field stations, traiiic controlling devices at each field station, a selector type communication system operable step-by-step through cycles of operation and including two line wires connecting said control oflice and said eld stations, means for transmitting either of two control conditions on each step of a cycle of operation from said control cnice to said devices at any particular station through the medium of said system and over said two line wires, and means for transmitting either of two indication conditions on each step of a cycle of operation from said particularstation to said control cnice through the medium of said system and over said two line wires simultaneously with the transmission of controls over said two line wires.

12. In a communication system for railroads, a line wire connecting a control office and a field station, step-by-step means at the control oiiice and at the field station operated in synchronism to successively complete a large number of channel circuits each of which includes said line wire, a direct current responsive device at the eld station and an alternating current responsive.

deviceV at the control office both in one ofl said' channel circuits, means for preventing said direct current responsive device from being affected by alternating current, means for preventing said alternating current responsive device from being affected by said direct current, means at the control office for supplying both direct and alternating current energy to said one channel circuit, means at the control omce for controlling only the direct current in said one channel circuit, and means at the iield station for controlling only the alternating current in said one v channel circuit.

13. In a communication system for railroads, a line circuit connecting a control oflice and a eld station, step-by-step means at the control ofiice and at the iield station operated in syny chronism for a plurality of steps comprising a cycle of operation, means at the control ofce for energizing said line circuit on each step, means at the control office for distinctively controlling the energization of said line circuit on each step, controlled means at the field station responsive to said distinctive energization from the control oiTice of said line circuit on each step, automatic means at the field station for selectively modifying the energization of said line circuit on each step without affecting the response of said controlled means, and means at the control office distinctively responsive to said energization of said line circuit on each step in accordance with whether or not such energization is modified by said automatic means at the eld station.

14. In a communication system for railroads, a line circuit connecting a control ofce and a field station, step-by-step means at the control oice and at the field station, means operating said step-by-step means through cycles of operation comprising a plurality of steps, means at the control office for energizing said line circuit on each step, manually governable means at the control oflice for distinctively controlling the energization of said line circuit on each of said steps, electroresponsive control means at the field station for each step distinctively responsive to the energization of said line circuit for that step only in accordance with said distinctive control of such energization at the control office, automatic means at the field station for distinctively controlling the energization of said line circuit o-n each of Vsaid steps without affecting the response of said electro-responsive control means, and electro-responsive indication means at the control ofiice for each step distinctively responsive to the energization of said line circuit for that step only in accordance with said distinctive control of such energization at the eld station.

15. In a communication system for railroads; two line wires connecting a control ofce and a field station; step-by-step means at the control oiiice and at the eld station operated in synchronism through cycles of operation, each cycle comprising a plurality of steps; a direct current source of energy in the control oilice; manually controllable means at the control oflice for selectively energizing said line wires with one polarity or the other on each step from said direct current source; an alternating current source of energy Y on each step said indication relay for that step is connected in series with said alternating current source to said line wires; a control relay at the eld station for each step distinctively responsive to the polarity of direct current energization of said line Wires for that step; automatically controlled contact means for each step at said field station; circuit means at said eld station including said automatically controlled contact for that step for allowing, when said contact is closed, the flow of alternating current in said line wires for that step without affecting the ow of direct current in said line wires for that step;

means for causing each control relay to be unafl fected by alternating current; and means in the control office for preventing interferences between the direct current and alternating current sources of energy.

16. In a communication system for railroads; two line wires connecting a control oice and a field station; step-by-step means at the control oilice and at the eld station operated in synchronism through cycles of operation, each cycle comprising a plurality of steps; means at the control oice for energizing said line Wires on each step with direct current; manually governable means at the control office for selectively determining the polarity of the energization of direct current on said line wires for each of said steps in accordance with the control to be transmitted for that step; direct current electro-responsive control means at the field station for each step distinctively responsive to the polarity of enerfgization of said line wires for their respective steps for controlling their respective devices; an alternating current source of energy; means for connecting said alternating current source to said line wires on each step; means at the field station for selectively controlling on each step the ow of alternating current in said Wires Without affecting the flow of direct current in said line wires for that step, said means acting in accordance with the indication to be transmitted for that step; and alternating current electro-responsive indication means at the control oflice for each step distinctively responsive to the flow or absence of alternating current in said line wires for that step for indicating the indication transmitted for that step.

RICHARD C. LEAKE.

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