US1071588A - System of selective control. - Google Patents

Description

G. E. SGRIBNER, J. L. MQQUARRIB & E. B. CRAFT.

SYSTEM OF SELECTIVE CONTROL.

APPLICATION FILED MAR. 12, 1910.

Pategted Aug. 26, 1913.

3 SHE-ETS-SHEET 1.

C. E. 5 crib/7e r.

J. L. M Qua/fie.

Kfifnesses:

G. B. SGRIBNER, J. L. MoQUARRIE & E. B. CRAFT.

SYSTEM OF SELECTIVE CONTROL. APPLICATION FILED MAR. 12, 1910.

3;,0'71588, Patented Aug. 26, 1913 3 SHEETS-SHEET 2.

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' [.iScr/bner. VI/V/ZCHQSSQSI J L. MOuam'e.

G. E. SCRIBNER, J. L. McQUARRIB-8z E. B. CRAFT.

SYSTEM OF SELECTIVE CONTROL. APPLIOATION HLiD MAR 12,1910.

entrain ras er hilt @lt lii ilfsi.

CHARLES E. SCRIBNER, 0F JERICHU, VEREUE'YT, Afifi JAMES L. MUQUAEEXE, 0F MONT- CLAIR, AND EDWARD B. CRAFT, 9F EACKEHSACK, NEW EEEQQEY; ASSEGNOES T8 WESTERN ELECTRIC COHPANY, OF NEW 3503K, H. Y., A GQR?UE&TIGN 0F ILLZNGIS.

SYSTEM 0? EELEGTIYFE GON'EBOL.

specification of Letters Patent.

Patented An 2%, @913.

Application and ism-eh 1s, 1am. 5eris1l'1o. eraser.

T 0 all whom it may concern:

Be it known that ,we, CHARLES E. Scars- Nun, Janus L. h'IOQUARRIE, and EDWARD B. CRAFT, citizens or" the United States, residing at Jericho, Chittenden county, Vermont; lrlontclair, Essex county, New Jersey, and

Hackeusack, Bergen county, New Jersey, re

spectively, have invented a certain new and useful Improvement in Systems of Selective Iontrohof which the following is in full, clear, concise, and exact description.

Our invention relates to systems of selective control and its object is to provide improved means for selectively controlling apparatus at a plurality of stations associated with a line.

Our invention is particularly applicable to selective systems of the general type wherein the switch mechanisms, at the respective stations of a line, comprise switch members normally movable in definite phase relationship subject to the control of sending mechanism at a station on the line, as illustrated, for example, by selective systems of the type employed in train despatching. In systems of the type mentioned, heretofore employed, electrou'iotive forces impressed upon the line from extraneous sourcesmay cause one or more of the switch mechanisms to operate and advance the corresponding switch members, thereby bringing the members atthe various stations into some other than their normal phase relationship. Or such extraneous electromotive. forces may operate to advanceall of said members from their normal positions. In either case the substation apparatus would be left in other than its normal condition so that upon a subsequent operation of the sending mechanism the switchesat the various stations would op crate abnormally, the result being a confusion of connections.

An important feature of our invention consists in the provision of means whereby false operation due to current from an extraneous source is prevented. This is [)I0- videcl for by dividing the movement of the switch members into two parts, one of which .may be termed the preliminary range of movement, and preferably consists of but a single step, and the other of which may he termed the selective range of movement. The switch in our system may be so related l sity of applying 9. restoring to the system that it can be advanced through its preliminary range only by current of one character and can he subsequently advanced through its selective range only by current of a ditlerent character. Vfith this construction current from extraneous sources, whether constant or interrupted, will not advance the switches at all if it is of one character, and if it is of the other character will at most advance them only through their preliminary range. in our system means are provided whereby the sending mechanism may send initial current or" one character adapted to advance the switcl'i-es through their preliminary range, after which said mechanism will send currentof a different character ada ted to further advance said switches. he sending mechanism is furthermore provided with means whereby when the switch members have been advanced to a position corresponding to any given station, a current of the same character the initialcurrent, may be .impressed upon the line to bring a signal or other device into circuit. This lastmentioned current, by reason of its character together with the fact that the switch members are at this juncture within their selective range of movement, will have no efiect upon the movement of the switlcl'i members.

From the above it will be apparent that in our invention theswitch members ifdisturbed atall by extraneous sources of current are moved to but a slight degree from their normal positions. Also itis obvious that if the extraneous current is impressed uponthe line at a point where it operates to advance certain of the switch members only. thereby disturbing the phase relationship of the switch members throughout the system, such disturbed phase relationship will be corrected upon the operation of the sending mechanism prior to the advance of any of the switch members-through their selective range proper.

In lone lines heavily loaded with substation equipment, the lines of a train dcspatching system may be, efliciency in the matter of power consumption is particularly desirable. By our invention a substation switch of the type wherein the movable member rotates in a'single direction may be employed, thereby obviating the nee es orcc to said member, the force of which would have to I; mentary be overcome in its operation, with consequent consumption of power. Switches of" this general type are not a part of our in-- vcntion, butt-heir employment is rendered ypracticalby our invention by reason of the feature already set forth whereby, definite phase relationship may be maintained. Other more specific features of our invention will be hereinafter set forth.

,Our invention will be more readily understood by reference. to the accompanying drawings, in whichv Figure l is a sender 'mechanism'wh /ch may be used with the system 'of our invention; Fig. 2 is a side view, partly in section, of switch mechanism adapted for use at the substations} Fig. 3 is a-fro'nt view ofsaid switchmechanism; Fig. 4 is a rear view of said switch mechanism; Fig. 5 is a perspective view partly infsection of the switch member and associated 'parts;'-and Fig. 6 is a circuit diagram showing a line equippedin accordance with the system of our invention, with sending mechanism and two sets of substation equipment. F ig. 7 is a fragsectional view showing details of the sending mechanism.

Like characters of reference are used to designate ,like parts throughout the several views. t

Referring. to Fig. 1, showing a sender mechanism adapted for use with our system, 7, 8 and 9 are parallel plates spaced in any suitable manner to form a frame or support 15 for the operating parts. Secured to the lower -face of-the plate 9 are two circular series of radially projecting contact. me

' hers 10 and 11, each of said series being insulated from the other. The contact me mbers comprising each series are, however, in electrical. connection. l2 isa shaft rotatably carried by said plates 7, 8 and 9 and adapted to be driven through one rotation by the sprin actuated gear mechanism 13, 14 and 15, w en the lever 16 is actuated to wind the driving spring of said mechanism. '17 is a' brush or wiper arm carried by said shaft 12 and adapted, as it rotates therewith, to normally sweep over-the members 11. of the lowercircular series and make successive contact therewith. As shown in the drawing, the circular serieslof members 10 is mounted in staggered relation to the lower series of members 11. All the members 10,; except the one designated in the drawing as 1.0, arehowever carried slightly above the members 11, whereby they are normally out of the path of the brush 17. Directly. above th inem bers 10 are keys 18,19,20, 21, etc, onec lreyf foreach said member'lO. Each said keyQ' -is slidably carried in. the plates 7, 8 and 9 and is adapted, when operated, to depress the corresponding member. 10, thereby I )ringmg the endef said member intofthe 65 pathsot the 17 llach, ofsaidkeys comprises a spring member 22, carryiire,- a latch 23 adapted, when said key is depressed, to engage the adjacent edge of the notch 24, within which notch said member 22 is guided. The end of the. plunger of each key is provided with insulation 25 adapted to prevent its electrical connection with the member 10. In the drawing, key 19 is shown in its operated position, wherein it is locked as described. The member 10 may be fixedly carried in the path of the brush 1? and, for a purpose hereinafter explained, said membernnay be mounted in positionto be engaged by the brush 17 during'its initial movement. No key is therefore provided for said member 10. The shaft 12 carries an arm 26 terminating in a member 27 adapted in its rotation to engage with the projecting end 28 of the spring member 22 of any key which maybe depressed. The arm 26 is so positioned on, the shaft 12 that the brush 17 is slightly in advance of the member 27, whereby said brush may make contact with any member 10 which may be depressed into its path before said member 27 reaches the projec. 'tion 28 of the corresponding key. 29 is a plate or contact ring fixedly mounted and 30 is a brushcarri'ed by the shaft 12 and adapted to'provide an electrical connection of said plate 29 with the brush 17. 31, 32 and 33 are terminals in permanent electrical connection with'the members 10, the members. 11 and the ring 29,- respectively, as clearly shown in- Fig. 7, In Order to more clearly show the construction of the sender,

the shaft and parts carried thereby are not shown in their normal positions in Fig. 1. Normally the parts mentioned lie in-such :1 position that the brush 17 will make contact with the member 10" during its initial movement. The direction of rotation of the shaft is indicatedby the arrow.

With the construction described, it is apparent that upon turning the lever 16 the driving spring of the gear mechanism willbe wound, thereby resulting in the rotation of the shaft 1.2 and pa'rts carried thereby. The shaft will, during its initial n'iovemcnt, bring the brush 17 into electrical connoctimi with member 10 and then successively into connection with all the members 11v of the lowercircular series and also with any of the members 10 of the upper series which may have been brought into its path by the depression of a key. With the relation of parts as described, it will be obvious that after the brush 17 has passed a depressed member 10, the member 27 will engage'the end 28 of the locking spring of said key, thereby forcing saidend in a radial (iii-cction'and withdrawing the latch 23 from its engagement. with the-edge of the notch 24, whereby said key will be automatically restored. The mechanism therefore provides 131 respectively.

means whereby a circuit extending from terminal 31- to the ring 29 may be completed once for each member ll engaged by the brush 17, andwhereby. a circuit extending from terminal 31 to ring 29 may be completed once for each key depressed, the-latter completions being interposed at will be tween any two of the former.

Referring to Figs. 2, 3, at and 5, showing a selector switch adapted for use with our system, 34 is a frame or mounting comprising the supports 35 and 36. An electromagnet comprising coils 37 is secured to support 36, said electromagnet being provided with an armature 39 pivoted between lu s 4O.

Mounted upon the frame 34 is a U-s raped auxiliary frame 41 comprising members 42 and 43, upon which latter the shaft 44' is rotatably carried. Fixed to the shaft 44 is a ratchet 45 adapted to be actuated by a stepping pawl 46 pivotally carried by the arm d7 secured to the armature The armature is retracted by spring 48. The stepping pawl is kept in engagement with the ratchet by spring 49. Spring 50 serves a holding pawl for the ratchet. Referring particularly to Fig. 5, the terminal structure of the switch comprises supporting plates 51 and 52 between which are clamped a continuous conducting ring 53, a conducting ring 5 which is continuous except for the terminal electrically separated therefrom, two adjacent terminals F6 and 57 and members 58., 59 and (30 adapted to insulate the members mentioned. The parts referred to constitute a unit which may be secured to the member 43 of the U-shaped frame il. Projecting from the members 54, 56 and 57 are the connection terminals (Si, (32, 63, (34 and (3.), Upon the shaft 44 are two sets of brushes, one set comprising brushes (38 and 67 adapted, in their movement, to connect ring with ring 54 or with terminal 55, and the other set comprising brushes (3% and (39 adapted to connect termi nal 56 with terminal 57. The brushes Cl? and 57 are shown in their normal position in which they connect ring with terminal The brushes (3S andlit) are carried by a clamp member 70 which in turn is adjustably secured to the shaft 44 by means of clamping screw 71, whereby said brushes may be caused to normally bear any desired angular relation to the terminals 56 and 57 with which ti 3 engage. With the construction described, the energization of the elcctromagnet by impulses of current causes the advance of the ratchet one step for each impulse, thereby causing the brushes .66 and 67 to more from their normal positioh, wherein they connect ring with terminal 55, to some other position, in any of which other positions they may join ring 53 with ring In the advance movementof the despatcher. .niechanism, already described, 15 located,

ratchet, the brushes G8 and (it) will obviously connect terminal 56 with terminal 57 at some stage of said movement depending upon the angular relation of said brushes to said-terminals.

Referring to Fig. (5, showing an embodiment of our invention in a selective signaling system, 72 is the sending station which in practice might be the ottice of a train At said station the sending said mechanism being so connected in circuit that the brush 17 is in connection with one limb 73 of the line and the two series of members 10 and 11 are, respectively, connected with opposite poles. of batteries 7+ and 7 5, the remaining poles of said batteries being connected to the remaining limb 7,6 of the line. The despatchers telephone set 77 may be bridged across the line as shown, impedance coils 78 and 79 being inserted in the line between the batteries 74 and and said set 77 as a means of preventing undue disturbance of the telephone of said set by selecting impulses. In the drawing, two way or substations S0 and 81 are shown associated with the line, the apparatus at said stations being connected in parallel with the line. The equipment at each station may comprise, in addition to the selector switch already described, other switching mechanism including a polarized relay 82, a locking relay 83, a key 8-1 and a bell, buzzer or other signal 85. The mechanism may derive its operating power from a battery 86. The armature 87 of the polarized relay 82 may normally beheld in its mid position by springs 88 and 8f) engaging with stops U0 and 91, respectively, whereby current of one polarity will cause said armature to tilt in one direction and. engage contact 92, and current of the reverse polarity will cause said arn'iature to tilt in the opposite direction and engage contact 93. One pole of the battery 86 is connected by conductor 94- with the operating magnet 37 and thence, through conductor 95, with the ring of the switch, Wllhl'QHl'lOfl twoparallel paths to the polarized relay 82 are provided. one of which paths is completed by brushes (36 and ($7 in their normal position as shown in the drawings, whereby the circuit thus partially traced is extended from ring 53 through said brushes to terminal 55, thence through conductor 96 to normally open contact 92 of relay 82, thence through armature 87 and conductor .97 tothe battery 86 In the normal position of-the brushes 6 and (37, the circuit just traced through the 0pcrating magnet 37 will therefore be completed by the polarizedrelay 82 when said relay is energized by current of such polarity to cause its armature to tilt in a clockwise direction and in no other position of said brushes will. said electromagnet 37 l dd be operated by such operation of the polar ized relay 82. The remaining parallel return path for the circuit through the operating 'electroma'gnct is from ring 53 through brushes and (37, conductor 98, normally open Contact 03, armature S7 and conductor 97 to the battery. This circuit is normally open and can therefore only be completed by the polarized relay when the brushes 66 and (37 are in some other than normal position. The operating electromagnet may therefore be ema-gizcd by the completion of either of the above described circuits and therefore may be energized by current of either polarity through therelay 82. It'will be observed, however, that each of the local operating circuits is subject to both the selector switch and the polarized relay and can be completed only under certain conditions with respect to both the polarity of the line current through the relay82 and the position occupied by the 07 at theinstant in question and that said that with the normal positions, said brushescannot be condition may be such that at no time will the energization of the relay 82 by current of other. than one polarity result in the operation of the electromagnet \Vith the arrangement described, it will be apparent brushes (36 and (37 in their caused to move more than a predetermined distancefrom normal by successive line im after having termiued polarity.

pulses, and that even this movement is possible only when the line current is of predestructure is such that said predetermined distance is limited to one step.

Referring to the circuit controlled by the switching mechanism, a circuit is shown including a signal 8-"). This circuit is shown as extending from battery 86 through conductor 99,-s'ignal 85, normally open terminals 56 and 57, conductor 100, conductor 96, normally open contact 92, armature 87 of relay 82, and conductor 9'? to the other pole of the battery 86. In parallel with the signal, 85,- a locking relay 83 may be provided, whereby when the circuit of the'bell is completed, that ofthe relay is also. The locking circuit of the relay 83 extends from battery-86 through conductor 99, conductor Tn the drawings the brushes 66 and 101, the winding of said rclay 83, locking contact 102 and armature 103 of said relay maining pole of the battery. \Vith the structure described, the brushes 68 and 69,

been moved the required number of steps from normal, willengage with terminals 56 and 57 and thereby prepare the circuits of the-signal 83 for completion by the polarized relay 82, which latter relay will respond to a current of proper polarity to tilt its armature in a clockwise direction: and, thereby com- 83, key 84 through conductor 105, to the re- 85 and relay plete said circuits. It will be observed that under the conditions existing at this junclure, the'operation of the polarized relay in a clockwise direction produces no effect upon the other circuits. The circuits of the buzzer and lockingrelay havlng. been completed as described Wlll remain complete tl1r-: ugh the locking circuit, already traced,

until key 84 is operated to open said circuits. Obviously, except for the locking means, the, hell would operate only during such time as the brushes 68 and 69 remained upon terminals 56 and 57. Under certain conditions this, however, might'be sufficient. Itwillbe understood that in the switches at -the respective stations, thebrushes 68 and the operator at sending sta .ion 72 wishes to signal station 81 and that in the switch at said. station the brushes (8 and 69 are so placed with respect to brushes 66 and (37 that threesteps are required to bring the former into engagement with terminals 56 and 57 The operator at the sending station will depress that .key of the sender which will bring a member 10 into the path of the brush 17 between the second and third of the members 11. Upon turning the lever 16 in a direction to wind the driving spring and then releasing the same, the shaft 12 will rotate through one complete rotation, the brush 17 first engaging member 10', whereupon battery 74 is connected with the line, thereby resulting in the operation in a clockwise direction of the polarized relays 82' at all stations. The operation of said polarized relays causes the completion of tions, whereby the switch brushes are advanced one step. The sender brush having passed member 10 next engages two members 11 in succession, whereby battery 75 is momentarily connected with the line twice. As a result, two impulses of current of such polarity as to operate the polarized relays 82 in a counterclockwise direction are impressed upon the line. The. operation of the polarized relays twice asgdescribed advances the brushes at all stations two steps, whereupon brushes 68 and 69 of station 81 are brought into engagement with terminals 56 and 57, thereby preparing the circuits of the signal 85 and looking relay 83 for completion by a r of polarizedrelay 82. This reversed operation is provided for by the key referred operating electromagnets 37 at all stah versed operation to above as having been depressed, whereby the brush 17 coming in contact with the member depressed by said key,'connects battery 74 with the-line, thereby momentarily com hating the circuit of the bell and locking re y at station 81. Said circuit .will, as already explained, be locked sub- }ect to. the Operation of key 84. The bell and locking circuit will of course be completed by the impulse under consideration only at station.81 by'reason of the fa'c't'that at this station-only are the'brushes 68 and i 69- in contact with terminals 56 and 57 at without affecting others.

this juncture.

From-the above it will be readily understood that if impulses of current of one polarity be impressed upon the line, said impulses will v operate each of the switches through its preliminary range only, which preliminary range, in the system shown herein, comprises but one step, although not necessarily so limited. Furthermore, said impulses may be of either polarity without advancing the-switches through more than said preliminary range. They may, more over, act upon part of the. circuit only whereby they might advance certain of the switches through their preliminary range This, however,

' would not result in false signaling by reason of the fact that the sender is provided with one or more members 10', whereby said sender impresses one or more preliminary impulses upon the line during its initial operation, the number depending upon the extent of said preliminary range, and therefore would bring any displaced switches into v proper phase relationship before actuating all of the switches.

lVhile we have described a form of our invention in which a current of one polarity is adapted to. control the movement of the switch members through the preliminaryrange and a current of a reverse polarity is adapted to move such switch members I comprising a member havmga preliminary through their selective range, it must be understood that our invention isnot limited. .to the use of a polarized relay nor to the use anism at each of a plurality of stations on said line, said switch mechanism .being adapted to be advanced througha preliminaryrange of movement under control of fiirrent of one character and through a further rangeunder control of current of an:

other character, and means cooperating with 2. The combination with a line, of a source of cprrent at a station on said line, sending mec anism for impressing positive and negative current upon said line, switch mechanism at each of a plurality of stations on. said line, said switch mechanism being adapted to be advanced through a preliminary range of movement under control of current of one polarity and through a'further range under control of impulses of reversed polarity, and means c'oiiperating with said switch mechanism for preventing the advance of said switch through more than said preliminary range under control of successive impulses of either one polarity alone.

3. The combination with a line, of a source of current at a station on said line, sending mechanism for'impressing currents of different character upon said line, switch mechanism at a plurality of stations on said line controlled by currents of different character, said switch mechanism comprising a member having a mechanism comprising a member having a preliminary range of movement and a selective range of movement, and means cooperating with said switch mechanism whereby current of one character adapted to control movement of said member through. one range will beinefi'ective for controlling'movement through said second range.

4. The combination with a line',of asource of current at a stationon said line, sending mechanism for impressingpositive and negative current upon said line, switch mechanism at each of a plurality of stations on said line controlled by said positive and negative current, said switch mechanism range of movement and a selective range-of movement, and means coiiperating with said switch mechanism whereby current of polarity adapted. to control the movement of said member through one range will be ineffective in controlling the movement through said second range. I

The combination with a line, of a' source of current at astation' on sa d line,

sending mechanism for impressing impulses of current of different character upon said line, and a selector switch mechanism com prising a movable member, at each' of a plurality of stations on said line, said. switch mechanism being adapted in a selecting operation to advance in response 'to initial current of one character and subsequently in response to current of another character only; 4 v

tii'lhe combination'with a line, of a source-of current at a station on said line,

h'tflldlllg' mechanism for impressingpositive and negative impulses of'current upon said line, and selector switch mechanism comprising a movable member at each'of a plurality ofstations on said line, said switch mechanism being adapted in a selecting op eration to advance in response to initial current of one polarity and subsequently, in responseto current of reversed polarity only.

7. The combination with a line, of a source of current at a station on said line,

sending mechanism fouimpressing positive and negative current upon said line, mechanism comprisinga movable switch member at each of a plurality of stations on said line; a circuitcontrolled by said member at a predetermined position, said mechanism operating in response to current of one po-' larity to cause the initial advance of said member and in response to current of reversedpolarity only tocause the subsequent I advance of said member tosaid position.

8. The. combination with a line, of a source of current ,at a station on said-line, sending mechanism for impressing positive and negative current upon said line, mechanism comprising a movable switch member at each ofa plurality ofstations on saidline, a circuit controlled ,by said member at a predetermincdposition, said mechanism operating in response to current of a given 110- larity to causethe initial movement of said member, in response to current of reversed polarity only to cause the subsequent movement of said member, and .in response to current of said given polarity to controlsaid circuit.

1). The combination with a line, of. a sourcc'of current at a station 'on said line, sending mechanism for impressing positive and negative current upon said line, mechanism comprising a movable switchmember at each of a pluralit" of stations on said line, a circuit controlled y said memberat a predetermined position, a signal controlled bysaid circuit, said mechanism operating in respouse to .currentof a given polarity to cause the initial movement of said member,

in response to current of reversed polarity only' to cause the subseq'uent'movement of said member, and in response to current of said given polarity to control said circuit.

10. The combination with a line, of a. source of current ata station on said line, sending mechanism for-impressing positive and negative current upon said line, mechanism comprisin ateach .of' a p firalityof stat-ions on said line, a circuit controlled by said member at a predetermined position, a relay controlled by said circiiit, and a signal controlled by said relay, said mechanism operat'ing in response to'eurrent of a g ven polarity to a movable switch member cause the initial movement ofsaid member,

cal to cause the subsequent movement of in response to'cnrrent of; reversed polarity,-

sai member, and in response to current of said given polarity to'control said signal.

' 11. The combination with a line, of a.

source of current at a station on saidline, sending mechanism for impressing; ost

tive and negative 'currentu pna sa lline,

a polarized relay atgeach 6f a pl iality of stations on said line,'a switch at'each 'of said 12. In. a selective. signaling system, the

combination with a line having a sendingstation and a. plurality of way stations con- .nected therewith, of-mechanis n at said sending station for lmpressin ferent character upon said line s. Step1 step selective device at each of said waytations embracing an electromagnet, unopcrating circuit for said electr'omagnct havng two branches, and a,c'ircuit closing .de-- vice connected with the line at' each of said way stations and operated by the currents of different character over said line to close the two branches of said operating circui respectively.

13. In a selective signaling systcln,-the

combination with a line having a sending station and a plurality ofway stations connected therewith, of mechanism at saidsending station for impressing currents of-different character. upon said line, a step-bystep'selective device at each of said way stations embracing an electromagnet, an operatingcircuit for said electromagnet having two branches, and a polarized relay connected with the line at each of said way stations adapted in response to current of one characterto close one branch of said operateurrents of difing circuit and in response to currents of another character to close the other branch of said operating circuit. I

14.- In a selective signalin system, the combination'wi'th a line he g asending station andaplurality of way stations connected therewith, of mechanism at said sending station for impressing currents of different character upon said line, a step-bystep selective device at each of said we s'ta tions, a switching device at each of sai wav stations responsiveto the currents of dii ferent character impressed upon the line at the sending station, and an operating circuit for said selective device having two bran hes each jointly controlled by said switching device and said selective device.

15. In a selective signaling system, the combination with a line having a sending station and a plurality of way stations. connected therewith, of mechanism at said sending station for impressing currents of dif' ferent character upon the line, a step-bystep selective device embracing an electromagnet and a movable member at each of said way stations, a circuit closing device connected with the line at each of the way stations responsive to the difl'erent character currents impressed upon the line at the sending station, and an operating circuit for said electromagnet embracing two branches one of'which is closed when .the movable member thereof is in one/position and current of one character is sent over the line, and the other branch of which is closed when the movable member thereof is in another position and current of another character, is sent over the line.

16. In a selective signaling system, the combination with a line having a sending station and a plurality of way. stations con nected therewith, of mechanismat said sending station for impressing currents of' different character upon'the line, a step-bye step selective device, embracing an electro-, ,magnet. a movable member and circuit closing contacts controlled by said movable member, located at each of said way stations, a polarized circuitclosing device connected with the line at each of said way stations and responsive to the currents of different characterimpressed upon the line at the sending station, and an operating circuit for said electromagnet comprising two branches one of which is closed only when the movable member thereof is in a given position and current of one character is sent over the line and the other of which is closed when said movable member is in other than the first mentioned position and current of a different character is sent over the line.

17. The combination with a line, of a sponse to current of one character to com-" plete one of said brancheswhen the switch is in its normal position and operate in response to current of another character to complete the other of. said'branches when the switch is in other than its normal position, and a second cir-uit jointly controlll by said switch and relay at a predetermined point in the advance movement of said switch.

18. The combination with a line, of a source of current at a station on said line, sending mechanism for impressing positive and negative current upon said line, an electromagnetically controlled switch at each of a plurality of stations on'said line, an actuating circuit for said switch comprising two branches, said branches being alternately rendered operative during the operation of the switch, a polarized relay adapted to 0perate in response to current of one polarity to complete one ofsaid branches when the switch is in its normal position and to 0perate in response to current of the reversed polarity to complete the other of said branches when the switch is in other than its normal position, and a second circuit controlled jointly by .said switch and relay at a predeterminedpoint in the advance movement of said switch.

In witness whereof. we hereunto subscribe our names this -11th day of March A. 1).,

CHARLES E. SCRIBNER. JAMES L. MGQUARRIE. EDWARD B. CRAFT. Witnesses Iavnvc MAQDONALD, MORGAN VVAsHBURN, Jr.

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