US2230859A - Train dispatching system - Google Patents

Description

Patented Feb.4, 1941 UNITED STATES PATENT OFFICE TRAIN DISPATCHING SYSTEM Original application August 27, 1931, Serial No. 559,671, now Patent No. 2,111,352, dated March 15, 1938. Divided and this application March 15, 1933, Serial No. 196,012

7 Claims.

This invention relates to improvements in train dispatching systems, and more particularly to an improved communication arrangement between the control station and the substations connected I) therewith.

This application is a division of our copending application Serial No. 559,671, filed August 27, 1931, now Patent No. 2,111,352, granted March 15, 1938, for Train dispatching systems.

In the train dispatching system to which the present invention is applied, a control station is connected through a single circuit with a plurality of substations in such a manner that by means of suitable units, train signaling, track switching, and other trafiic regulating operations and the like, may be performedat any one of the substations in accordance with instructions transmitted from the control station. The control station is also apprised of the track and roadside signal conditions by means of so-called GS indications, i. e., by means of impulses generated at the control station and afiecting indicators thereat, but modified by the condition of the traffic regulating devices at the substations. The communication is by coded impulses directing a substation to perform certain operations or, at the will of the control station operator, informing the latter whether instructions have been carried out at a particular substation. Thus, the control station automatically and periodically tests trafiic regulating conditions at all the substations, i. e., obtains information on the positions of track switches, semaphores, track relays, etc.

If it is desired to effect changes at a substation, the operator at the control station adjusts an impulse transmitter to send code symbols typical for the desired substation and the operations to be performed thereat. A receiver is provided at each substation but only the receiver of the desired substation shall respond and actuate the associated control units in accordance with the code symbols. For the sake of economy and rapidity of communication, the stations are interconnected by a single circuit over which time channels are established through which various stages of the communicating are performed. A definition of this term is given at the end of this specification.

The time channels are used also for the purpose of conveying report signals to the control station. The traffic governing devices at the substations are associated with the control circuit over certain channels to actuate receivers at the control station in accordance with code impulses that have originated at. the control station. Over the same channel both control and report symbols may be sent. The faithful coop.-

eration of the control station and substation equipments is insured by synchronously establishing the channels through which the communication takes place and making effective only those substation channels through which it should take place.

It will be obvious to those skilled in the art that the present invention may be modified in many respects without exceeding the scope of the appended claims. The dial and distributing switches may be provided with contacts that cooperate with each other in response to other than rotary motions. In fact, any electromechanical circuit switching arrangement may answer the purpose. The expressions "dial switches, ,distributor switches and the like, were arbitrarily chosen and are intended to apply to any circuit switching device suitable for the purpose. Similarly, the connections to the brushes and stationary contacts of the switches and distribu-v tors may be reversed; the lamps, polarized relays andthe like replaced by other suitable devices, etc. In the systems herein described, direct current is used for certain, and alternating current for other, phases of the communicating and control operations. This also may be modified and varied to suit particular operating requirements. The synchronizing arrangements may be replaced by other arrangements which will insure the timely cooperation between the control station and the substations. The rail switches, track relays and semaphores, which are defined as traffic governing devices, may be altered or supplemented by other traffic governing or testing devices, etc.

These and other departures from the specific exemplification of the invention will be apparent to those who may wish to employ the characteristic features of the invention. Most of these features are applicable to train dispatching systems of widely varying character and need not be employed in totality.

These and other features are diagrammatically illustrated in the accompanying drawing, only those parts of a train dispatching system being shown which are necessary for explaining to one skilled in the art one manner in which the invention may be practiced.

Referring to the accompanying drawing, Figs. 1A and 1B, taken together, illustrate one form of apparatus embodying our invention. Fig. 1A shows apparatus which is located atsthe control office from which all other units are controlled and to which their positions are automatically reported, while Fig. 1B shows apparatus located at one of a plurality of substations scattered along the railway route to interpret symbols transmitted from the central station and control adjoining groups of controlled or operating units, and to transmit to the control station reports indicating the actual positions of controlled units. 9 is a control channel which, in the present example, is constituted by a line circuit connecting the central station to all substations. It is grounded at its far end. 54 and 44 are grounded batteries at the central station which supply the energy for control and report symbols, respectively.

As will hereinafter be explained, the office apparatus of Fig. 1A is arranged for the control of apparatus at a plurality of field stations, for example, twelve, each similar to Fig. 1B, and it is to be understood that the office apparatus also includes an operators control board such as is shown in Fig. 1 of our Patent No. 2,111,352, which comprises a plurality of similar sections, or substation control panels, one for each station, on which are localized the control and indicating units for the substations.

At'each substation there is a track relay Is, to indicate whether an adjoining track section is clear or occupied, and, as shown in the above mentioned patent, at the top of each central station section there is an indicating lamp similar to lamp'll to indicate the position of the corresponding track relay. The track indicating lamps are not shown herein, but it is to be understood that they are located in sections of a track diagram to show visually the relation of the section indicated to the actual tracks.

The apparatus at each substation, as shown in Fig. 13, may include a group of semaphore signals 1, which may be controlled by the apparatus of our invention to indicate clear'for an eastbound or westbound train movement, or to indicate stop. In the corresponding sections of the central station are control levers 53, of which for simplicity but one is shown in Fig. 1A, each hav ing three operating positions corresponding to the three positions of the semaphores or roadside signals; and associated with each lever 53 are three indicating lamps, 49, 55 and 5|, one of which is lighted to indicate the position actually occupied by the semaphore.

The apparatus at each substation may also be arranged for the control of a switch machine [8 for operating a track switch, and for each controlled track switch the office apparatus includes a switch lever 55, each operable to two positions normal and reversed. Associated with each switch lever are three indicating lamps, not

shown, but similar to the lamps 49, 5|! and 5|.

The leftand right-hand switch indicating lamps, respectively, indicate that the track switch is closed and locked in its normal or reversed position. The middle lamp indicates that the track switch is open or unlocked, which may mean that it is in the process of throwing over or that it has failed to complete its stroke and lock up ready for the passage of a train.

In addition to the units l8, l1 and I8, there may be also other trafiic regulating or indicating devices associated with the substations. The single control wire 9 with ground return as shown (or with metallic return), is sufficient for transmitting all necessary control and report symbols between. the central station and the substations.

The apparatus normally operates automatically and continuously to receive report symbols from each station in turn in recurrent cycles, in which case the manual switches 35, 35, 45 and 56 occupy their left-hand position as shown, these switches being thrown to the right when it is desired to transmit control signals or symbols to change the position of one or more of the controlled units at a station.

At each substation is shown a local battery l9 to furnish power for operating the track switches, railway signals and reporting mechanisms, sub ject to control symbols transmitted over the line circuit 9.

One section of the operators control board is thus adapted entirely to control a typical group of railway traffic regulating or indicating units comprising one track switch (or group of switches working simultaneously), and one roadside signal or group of signals, and also adapted for receivingreports which indicate one of three conditions for each. In addition, it is adapted to receive reports indicating the position of one track relay. Part of these units may be omitted, or other units up to the equivalent of the units associated with the typical section may be included.

Referring to Fig. 1A, 6 is a motor at the central station receiving power from battery and driving a shaft 20 continuously. 8 designates a governor mounted on the shaft comprising centrifugal brake shoes 5 revolving within a stationary ring I At a predetermined speed the brake shoes are thrown into frictional engagement with the ring H by centrifugal force and further increase of. speed is thereby precluded. By this means shaft 25 is driven at accurately constant speed (for example, one revolution per 0.2 second) Mounted upon the shaft 20 and insulated therefrom are six dial switches 2!, 22, 23, 24, 25, 25, each consisting of a revolving brush arm .2 and a group of nine contact segments or spaces lettered a to 2', respectively. A cam 21 also mounted upon the shaft 2|] controls a follower 28 spring-biased toward the cam. The follower controls a pawl 29 which actuates a twelve-tooth ratchet 31 in such a manner that the latter advances one step at the end of each revolution of the shaft 20, that is, While the brush arms 2 are advancing from position i to position a, and completes one revolution or cycle in twelve steps. The dial switches 2 i-Zfi perform one complete revolution upon each revolution of the shaft 25, or twelve revolutions per cycle of ratchet 31.

30 designates a shaft driven by the ratchet 31, and 3|, 32 and 33 designate twelve-point distributor dial switches having their movable con tact or brush arms mounted upon the shaft 3!) and insulated therefrom. The stationary contacts or segments I, II, III, etc., of distributor 33, as the brush arm revolves, connect the line 9 successively to the brush arms of dial switches 24, 25 and 26, each of which in turn, during the time it is connected to the line, comiects successively wit-h its own group of segments a, b, 0, etc, Th brush arms of switches 2|, 22, 23, 24, 25 and 25 are aligned to contact simultaneously with their corresponding group of segments. Thus, at the instant illustrated, each brush arm on shaft 20 contacts with its segment 9. During twelve revolutions of the shaft 20 the control line 9 will be connected successively to each segment of switch 24, then to each segment of switches 25 and26 and then, in turn, to each segment of nine other switches, not shown, but similar to 24, .and 26.

Each position I, II, III, etc. of distributor 33 on shaft and the associated dial switch 24, 25, 26, etc. on shaft 20 is assigned to a difierent station, and each of the positions a to i, inclusive, of shaft 20 is assigned to a different code step. Each code therefore comprises nine steps corresponding to one revolutiton of shaft 20, and the recurrent cycle during which connections are established to each of twelve stations in turn corresponds to one revolution of shaft 30.

Referring now to Fig. 1B 66, 61, 60 and 68, respectively, are a motor, a battery, a shaft, and a governor, similar to the parts 6,], 20 and 8 already described, but located at a substation along the railway. 63 designates a sleeve mounted upon the shaft 60' and driven thereby through friction. Upon this sleeve are mounted the insulated movable contact or brush arm of a distributor switch 6| and a single tooth ratchet 62. Switch BI has nine positions in which contact segments a to 2, respectively, are closed. In position a, ratchet 62 is engaged by a detent 65, which may be disengagedby the energizing of a magnet winding 69. A spring-biased pawl I6 also engages ratchet 62 and is so located as to stop the rotation of switch 6| 'withits brush arm in engagement with contact 6, until pawl 16 becomes disengaged by the energization of a magnet 'II.

Each of the switches 2| to 26 is shown for illustration with groups of equally spaced stationary contact segments a to d and e to i, with larger spaces between segments d and e and between segments 2' and a. The distributor switch EI- is shown with the nine stationary contact segments all symmetrically spaced; In practice, all of these dial switches may have a larger number of stationary contact groups as may be required. The governors 8 and 58 are so adjusted that the brush arms they control will advance from the first segment a to segment d, or" from the fifth segment e to segment i, in approximately equal time, but owing to the increased space following segments (1 and '2' on switches ZI to 26, they will b-e'somewhat later in returning to the starting point e or a than distributor BI, or at least in no case, even with the maximum deviations from normal speed, will the latter arrive at the starting point later than the former.

Segments a of the dial switches 24, 25, 26, etc. are permanently connected to the positive terminal of battery 54, and serve to start all substation dial switches simultaneously for each revolution.

On the first step of each code, that is, when the dial switches at the ofiice and stations have their arms a in contact with segment a, a positive impulse is delivered to the line over a circuit which may be traced from the positive terminal of battery 54, contact a and .arm 2 of dial switch 24, 25 or 26, contact I, II or III and brush arm 2 of the distributor switch 33, segment a-f and arm 2 of dial switch 23, switch 40, line 9 to the first station, thence over arm 2: and contact a of dial switch 6!, through'the relay windings H5 and H6 and magnet 69 to line 9 leading to the next station, andso on through each station in turn toground, thence back to the mid-point of battery 54. Magnets 69 at all stations being thereby energized, each ratchet E2 is :released by its-pawl 65, and all the dial switches 5| start in unison with switches 2I to 26.

As already mentioned, the switch arms at the ofiice and stations pass over segments b, c and d at approximately the same speed. These segments are used to transmit over the line during each revolution a distinctive symbol calling only that substation required to respond during that revolution, the symbol consisting of positive or negative current on two of the three channels b, c and d.

At each of the dials 24 to 26, two of the three segments b, c and d are connected to the positive or negative terminal of battery 54, while the third is dead. The combination of positive, negative and dead segments on each dial is peculiar to that dial only and constitutes a calling code for one substation which is arranged to respond only to signals transmitted by that particular dial. While I have shown only three dials, 24, 25 and 26, each arranged to call one substation, it should be noted that additional dials, with corresponding segments on the dials 3| to 33, may be provided for any required number of substations. The three segments b, c and d assigned for calling codes will suffice for twelve distinct codes, viz: codes involving three choices of one dead channel and four combinations of polarity on the remaining two segments.

At the substations, these calling and selecting symbols are given effect by the operation of two doublewound polar relays biased to remain in their last operated position, having restoring coils II 5 and H6 and operating coils IIB and II9, as shown in Fig. 13. On the first step of each code, the positive impulse transmitted over segments a energizes winding H5 in such a direction as to cause contact I2I to move to the left while winding H6 is energized in the opposite direction to cause contact I20 to move to the right, so that the circuit controlled by these contacts is opened at two points at the beginning of each code. The operating coils II 8 and H9 are connected in accordance with the station call to two of the segments 17, c and d; that is, in the case shown, to segments 17 and c and to the outgoing section of the control line .9, in such a direction that a positive impulse over segment b is required to operate contact I 2i to the right, and a negative impulse over segment 0 is required to operate contact I20 to the left. It will be assumed that the station shown in Fig. 1B is the one corresponding to position I of distributor 33; accordingly in Fig. 1A segments b and c of dial switch 24 are connected to the positive and negative terminals of battery 54, respectively.

During one particular revolution, the contacts I20 and I2I, when closed as described, establish and maintain, during that revolution only, a localcircuit from grounded battery I9 to .a polar relay contact I23 controlled by a coil I22 which is connected in series with the control line 9 when a channel is established over the segments 1 of dial switches 24 and BI. If positive current is received during the sixth step, contact I23 is operated to the left, completing a local circuit through neutral relay I24 to ground, to set up circuits for receiving con trol symbols during the remainder of the revolution. If negative current is received during the sixth step, contact I23 is operated to the right, as shown, and completes ,a local circuit through neutral relay I25, which sets up circuits for transmitting report symbols on succeeding steps.

The fifth step of each code is employed for synchronizing purposes, to insure that a substation dial switch GI, will get into step with the dial switches 2| to 26 even if thrown out of step. On the fifth step, an alternating current impulse is transmitted from the grounded alternator II3 over segment e of switch 24, 25 or 2B, segment I, II or III of switch 33-to the control line 9 and thence over arm 2: and segment e of dial switch GI and the primary winding of a transformer H4 at each station, to ground.

As already mentioned, a magnet I1 is provided to release the pawl I6 when arm 2 of dial switch BI is on segment 6, and the segments are so spaced that arm .2 of dial switch 6| will make contact at segment e somewhat before the corresponding contact is closed at switch 24, 25 or 26. Magnet 11 is connected through a condenser III to the secondary of transformer II4, the circuit being tuned to respond selectively to the frequency of alternator II3. When the office dial switches arrive at step e, current will be induced in the secondary of transformer II4 to cause the magnet 11 to release the pawl IE, ratchet 62 being so positioned as to permit arm 2 of dial switch (ii to start exactly in step with the arms a of the ofice dial switches.

Even if distributor 6| is entirely out of step, as for example, when the system is first started in operation with the dial switches in random positions, it will revolve to segment e at some time within its first revolution. There it will be held by its pawl I6 until it is released by current to which the magnet 11 is responsive. This canoccur only when the line is connected over a segment 6 at the ofiice to the alternator 3, since current of the required character is supplied over no other segment. Hence, even under the condition assumed dial switch 6| will start its second revolution in step with switches 2| to 26.

When arm 2 of dial switch 6| as released by magnet 'I! has advanced until arm 2 makes contact'with segment a, it will be stopped again by engagement of the ratchet 62 with the pawl 65. A moment later the ofllce dial switch will connect the line through its segment a to the positive terminal of battery 54 as already described, to again release arm .2 of dial switch BI exactly in step with the arms a of the ofiice distributors, by the energization of magnet 69.

The second starting pawl 65 serves to correct any variation from synchronism which may have occurred during approximately one-half revolution, but is not capable of bringing the commutators into step from a random position as may be done by the pawl Iii, for the reason that magnet 69 is responsive to direct current, whether the current originated at segment a or at any other segment.

The sixth step of each code is employed to effect a manual selection to cause the transmission either of report symbols or of control symbols during the succeeding steps of each code.

The-segments f of dial switches 24-26 are connected through manual selector switch 56 either to the negative terminal of battery 54, with the mechanically interlocked switches 35, 34, 40 and 56 to the left, as shown or to the positive terminal, with these switches to the right; The former connection effects the trans mission of anegative impulse to the line to establish reporting loop circuits at the called substation by energizing relay I25, as already described, and also establishes connections to control indicating lamps such as 49, 50 and at the ofiice. The latter connection effects the transmission of a positive impulse to the line and conditions the office apparatus for transmitting control symbols in accordance with the positions of the control handles 53 and 55, and by energizing relay I24 conditions the selected station to receive these control symbols to effect the operation of the controlled units.

If it is desired to transmit one or more control symbols immediately, without awaiting the moment in the automatic cycle when the controlled unit in question would be connected to the corresponding oflice lever, the shaft 30 carrying the distributor dials 3| to 33 may be advanced manually to the position corresponding to the unit to be controlled, where it will remain during one revolution of the shaft 20. The dial selected'by the distributor 33 will transmit the calling code for the desired substation and establish the necessary local channels for exchanging report or control symbols.

Assuming the manually operable switches 35, 34, 40 and 55 to be to the left, as shown, the seventh, eighth and ninth steps provide three report signals for indicating the condition of the signals, track switch and track section at the selected station. The manually operable switch 40 in its left-hand position connects the line at will to the brush arm of dial 23 (as shown), while in its right-hand position it connects the line directly to the segment a, f of the same dial, and thence to the brush arm of dial 33. At the instant illustrated, and the position illustrated for switch 40, the line 9 is connected through segment g, i of dial 223 through neutral relay coil 4i and polar relay coil 42, to the positive pole of battery 44, and thence to ground. The battery is also connected through a coil 43 opposed to the coil 42, and through an artificial line or resistor 45 to ground. At the instant illustrated, that is, with the brush arms on segments g, the line 9 is connected to ground through a loop circuit associated with one controlled unit (at a substation), this loop having three conditions, each indicating one state of a controlled unit (e. g., a semaphore) at this substation, viz: closed through low resistance, closed through high resistance, and open circuit. Assuming the station of Fig. 133 to have been selected so that relay I25 is energized, this circuit may be traced from the incoming line wire 9 over brush arm 2 and segment g of dial switch 6|, a back contact of relay I24, switch I35, resistor I 38 to the outgoing line wire 9; while at each non-selected station the circuit extends from the incoming line wire 9 over brush arm z and segment g of dial switch SI and back contacts of relays I24 and I25 in series to the outgoing line 9, and thence to ground at the end station. In the case illustrated, assume the loop circuit at the selected station to be connected into line 9 as in the first condition; current passing from battery 44 through relay coils 42 and 4| to the line is a maximum. The resistor 45 is so adjusted that the magnetizing force exerted by the coil 42 under this condition exceeds that exerted by the constant current passing through coil 43 to the resistor; and the right-hand contact of the polar relay 43 will be closed. The front contact of the'neutral relay II will also be closed.

. The high resistance in the second condition of the loop circuit is so chosen that it will reduce the magnetizing force, due to linecurrent through the coil 42, to a value less than that in coil 43, with the result that the left-hand contact of the polar relay will close, but the neutral relay 4| will still be energized sufficiently to close its front contact. However, if the line circuit is broken at the substation loop, the polar relay will close its left-hand contact, and the back contact of the neutral relay will remain closed.

It will be observed that the resistor connected to the polar relay coil 43 corresponds in part with the artificial line or balancing network employed in certain duplex telegraph systems, but differs in that it is not required to balance the line characteristics but merely to produce an effect less than that of the normal line impedance and greater than the line impedance when the latter has been increased to several times its normal value. For this reason a plain resistance as shown, traversed by a constant current, will ordinarily sufiice. However, in cases where exceptional line constants make it desirable, the resistor may be replaced by any wellknown type of artificial line, asindicated at 45 in Fig. 7 of our Patent No. 2,111,352, and the battery current may then be cut off at each step and reapplied simultaneously to both windings 42 and 43, by the provision of another dial switch on shaft 28 as explained in the patent.

Referring now to the circuits controlled by the line relays 4| and 42, it will be seen that the front contact of the neutral relay 4| and the right-hand contact of the polar relay 42 are connected to the positive pole of battery 52 and the back contact of relay 4| and the left-hand contact of relay 42 are connected to the negative pole, the midpoint of the'battery being grounded. At the instant illustrated, the contact of the polar relay is connected over switch 35 through brush arm 2 and segment 9 of dial switch 2|, through coil of polar relay 46 and through segment I and brush arm 2 of distributor dial 3|, to ground. The polar relay'4G is designed to have a substantial bias toward its last operated position, so that either contact when closed remains closed until reversed by reversal of current in the operating coil. So long as the circuit just described is maintained, the relay 46 closes its left-hand contact if the right-hand contact of relay 42 is closed, and closes its righthand contact if the left-hand contact of relay 42 is closed. If the operating circuit through 46 is.then interrupted, its contact remains closed at the last operated position until the operating tor dials 3| and 32 are closed through segments I, I, the polar relays 4t and 41 thus assume positions which are determined by the positions (at that instant) of relays 42 and 4|. When the distributorand dial switch arms have moved on to other segments, the relays 46 and 41 maintain their operated positions until the next occasion when their operating circuits are closed through segments g--g and 1-1.

The movingcontact of relay 41 is connected to the positive pole of battery 48, the negative pole being grounded. The right-hand stationary contact is connected through an indicating lamp 43 to ground. The left-hand contact is connected to the moving contact of the relay 46 and thence, according to the position of the latter, either'through the right-hand contact and indicating lamp 5G to ground, or through the left-hand contact and indicating lamp 5|, to ground. Since the relays 4B and 41 repeat the positions of relays 42 and 4|, and since the latter are dependent on the resistance of the loop circuit which is connected at that instant in the line, the indicating lamps 49, and 5| indicate the connection (or absence of connection) through theloop circuit at the instant when connections are established as described; if'the loop circuit is open, neutral relay 4| will be down and indicating lamp 49 will light; 'if the loop circuit is closed through high resistance I35, relay 4| will be up and relay 42 to the left, under which condition indicating lamp 5|] will light; if the loop-circuit is closed through low resistance, relay 4| will be up and relay 42 to the right, and indicating lamp 5| will light. Furthermore, after the operating circuit through the coils of relays 45 and 41 has been interrupted at the distributor dials 2|, 22, the lighted lamp will continue to burn until the operating circuit isreestabli'shed, at which time the resistance of the substation loop circuit will again determine which of the three indicating lamps shall light.

As described, the indicating lamps 49, 50 and El are controlled byoperating circuits extending from the segments I--I of distributor dials SI and 32 to segments gg of dial switches 2|, 22. Similar circuits may extend from the segments I-I through other pairs of relays similar to 46 and 41, which are controlledover segments 71-71 and 13-i of dial switches 2| and 22 in accordance with the positions of thecontacts of relays 4| and 42 on the eighth and ninth steps of the code, to control-other groups of lamps similar to-49, 50 and 5|. At the endof one revolution of the brush armsof dial switches 2| and 22 the brush arms 2 of distributors 3| and 32 will advance to segments II-II. From these segments three other pairs of operating circuits, controlling three other grcups of indicating lamps, may extend to the segments g-g to z'--i of distributor dials 2| and 22. Three other groups of indicating lamps may be controlled by circuits terminating on the segments III, III of distributor dials3| and 32, so that we may have in all three times three, or nine groups of indicating lamps controlled by the line circuit 9 successively as the distributor brush arms revolve. If nine substation loop circuits are successively connected in the line; each group of the nine groups of indicatinglamps will indicate the condition of the corresponding substation loop circuit when last connected, thereby indicating the position of the corresponding operating unit which controls the loop circuit. In the case of operating units having only two positions, such as track relays, the high resistance connection at the loop circuit may be omitted, together with relay 46 and indicating lamps 5E] and 5|. The two required indications will then be produced by open and closed conditions of relay 41, resulting in dark and light indications at the lamp 49.

Instead of receiving reports to indicate the position of operating units at the substations, it may be desired to transmit control signals or symbols to change the position of one or more controllable operating units.

The manual switches 34, 35, 49 and 56 will then be thrown to the right. Switches 34 and 35 will open the control circuits for all indicating lamps. Switch 56 will be instmmental in transmitting a symbol to render the desired substation receptive to control symbols, as hereinbefore described, and switch 49 will connect the line 9 through segment a in all positions of distributor dial 23 to the brush arm 2 of distributor 33. At the instant illustrated, line 9 will be connected through seg ment 0. of dial 23 and segment I of dial 33 to the brush arm of distributor dial 24, and thence over segment g to the upper blade of three-position control switch 53. When the brush arm of distributor dial 24 advances to segment h, the circuit will be transferred to the lower blade of control switch 53. Thus in the two successive time channels in which the brush arm of dial 24 makes contact at g and h, respectively, the control line is connected first to the upper and then to the lower blade of manual switch 53. According to the position'of the latter, line 9 is connected to the positive or negative pole of battery 54 or to neither in the following order:

Upper position: Neither-negative; Middle position: Negative-positive; Lower position: Positive-positive.

The receiving elements at a substation are arranged to respond selectively to these three combinations of current during two time channels, establishing a distinctive roadside signal or semaphore indication in response to each combination.

Similarly, segment i of dial 24 may be connected through manual switch to the positive or negative pole of battery 54, and transmits a positive or negative current impulse over the control line to select one of two possible operations of another controlled unit at a, substation. Similar branch circuits, including other control switches, may extend from segments g, h and i of dials 25 and 26. During three successive revolutions, as the dials 24, 25 and 26 are connected successively to the line through dial 33, nine control channels will be established. One two-position operating unit, such as a track switch, may be controlled over any one of these channels; any three-position unit, such as a group of roadside signals, requires to be controlled over two such channels.

It has already been explained that on the sixth step of the code contact I23 of relay I22 is positioned to pick up neutral relay I25 or I24 at the selected station, depending upon whether report or control symbols are to be transmitted on succeeding steps. It will be seen from the drawing that when relay I24 or I25 is energized, the opening of its back contacts causes the line current to pass through loop circuits in series With the control line 9 over segments 9, h and i of dial switch 6I during successive operating stages of the distributor either to receive control symbols or characteristically to affect report symbols, viz: from segment 2' through polar relay coil 126 or through report switch I32 to the outgoing portion of control line 9; from segment it through polar relay coil I28 or report switch I33 to the same point; and from segment g through polar relay coil I39 or report switch I35 to the same point. Assuming switches 35, 34, 40 and 56 to be to the right, relay I24 will be energized and relay I25 deenergized; the back contacts relay I24 are therefore open and current through the loop circuits must traverse the coils of relays I26, I28 and I39. Report switches I32, I33 and I35 are bridged by back contacts of relay I25 which are therefore at this time short-circuited and ineffective.

Line current through the channels 9, h and 2, respectively, traverses the relay coils I39, I28 and I26, and determines the positions which their respective contact fingers I3I, I29 and I21 will assume, and which (by virtue of inherent bias toward their operated positions) they will maintain until reversed by opposite current in their operating coils. Thus the position of the contact fingers I3I, I29 and IZ'I is determined by the polarity of line current through the corresponding channels g, h and i in that revolution of dial 6i after relay I24 has been energized as described in response to the transmission of the calling symbol for this substation. The coils I26, I28 and I39 are connected to close their respective contact fingers to the right when the current through them is positive, and to the left when negative. Thus when relay I26 is actuated by positive current, contact I2! moves to the right, connecting the local battery I9 to the reverse operating circuit I38 for the track switch. As shown negative current has been last received in channel 2', and finger I21 is to the left, energizing the normal track switch operating circuit I31.

When operating coil I23 receives negative current over channel h from the lower blade of control switch 53 it operates its contact finger I29 to the left, energizing local control wire I39 to set up roadside signals for eastbound trafiic. This occurs irrespective of the position of finger I3I but when finger I29 is closed to the right by positive current in its operating coil, it interrupts the circuit to the eastbound wire and connects the battery I9 to contact finger I3I. The position of the latter, according as positive or negative current fiowed through coil I39 during channel 9', determines whether battery will now go on local wire I4I that sets the roadside signals for westbound trafiic, or on local wire I49 that sets them to stop.

Response to control symbols over channels 9, h and i, as just described, was dependent upon the previous receipt of positive current through manual switch 56 and channel causing contact finger I23 to close at the left and energize relay I24. When the manual switch 56 is closed to the left, as shown, negative current will fiow in channel I, and contact finger I23 will close at the right and energize relay I25. The relay coils I26, I26 and I39 will then be short-circuited by contacts of the deenergized relay I24 and therefore rendered ineffective; but the contacts of relay I26 will be open and the impulses sent during channels g, h and 2', respectively, will be characteristically affected by the positions of report switches I32, I33 and I35. may be, for example, a contact of a track relay Report switch I32 I6 used to indicate whether a track circuit is clear or occupied. When open, as shown, it will cause an indicating lamp such as 49 in Fig. 6

' (but controlled over channel 2') to light. When locked. An indicating lamp similar to. 50 will light. When open it may indicate that the track switch is closed and locked in its reverse position and may cause the indicating lamp corresponding to 49 to light.

In like manner the report switch may be actuated by a roadside signal mechanism, or equivalent circuits may be closed through relays associated with the roadside signals, and the three resulting conditions in the loop circuit, viz: open, closed through high resistance, and closed through normal line resistance may control the set of indicating lamps associated with channel g at the central station. The three indicating lamps associated with channelg and report switch I35 may indicate, respectively, that the signals are set up for eastbound traffic, set up for westbound trafiic and set at stop.

In resume, using dial switches of only nine positions on shaft 20 and of twelve positions on shaft 3%, as shown in the drawing, there could be handled twelve substations (three shown), central being able at each to control one track switch (or group of such) to twopositions and one roadside signal (or group of such) to three positions; central also receiving continuously from each in succession (except when sending control symbols or codes), automatic reports about one track switch (or group) having three conditions, about one roadside signal (or group) having three conditions, and about one track relay having two conditions.

Nine time channels to each substation, set up by the synchronous operation at central and at substations of nine-position revolving dial switches, are shown utilized as follows:

Positive on channel a starts oil all sub-station dials in step with central. (Fig. 1B, magnet 69 and detent 65). Substation dials gain slightly on central, so Will be already stopped, and will start each cycle exactly with central. This impulse on 0. also restores to normal or open contact condition (wiping out the influence of past codes), the two code receiving polar relays at all substations (I20 and l2l, Fig. 1B). It is by the twelve possible combinations of polarities in each of these two relays with their connections to the three time channels b, c, d, that each substation is differentiated from the others and is adapted to answer just one of the twelve symbols or codes.

Positive and/or negative impulses on channels I), c, d, constitute the substation selecting symbols or codes. Each one of these (twelve possible) is determined by the positive or negative battery connections on two out of the a, b, 0, segments of dials 24, 25, etc.

Alternating current on channel 6 puts all substations in synchronism with central, even if badly displaced.

Positive or negative goes out on channel J, according to the right or left position of manual switch 55, and this choice determines whether the impulses to be sent on channels 0, h, 2', shall cause movement of roadside signals, track switches, or the like, or shall light indicating lamps at central to report conditions of the track switch, track relay, semaphore or the like.

Channels g, h, when manual switch 56 is in the right-hand or control position, carry the codes that actually determine motion of roadside signals at the selected substation. As illustrated, only three codes are sent on g, h (eight are possible, using either of two polarities on either or both of two channels). More are not needed to control roadside signal conditions and would complicate substation receiving arrangements.

Channel 2', with manual switch 56 .in righthand control position, carries a two-unit code (positive or negative) to set the track switch to reverse or normal.

Channels g, h, i, when manual switch 56 i in left-hand or report position, carry no codes but are used as mere individual channels for connecting a battery at central to individual substation loops, each associated with a track switch, a roadside signal, or a track relay, during which connections these three loopimpedances are compared, individually, to an artificial line at central and their conditions individually recorded at central on. lamps.

In many aspects the various features of the present-invention are applicable to all types of train dispatching systems, and particularly to those in which devices at the control station and substations are operated in synchronism. As generally used, the word synchronism is applicable both to independently and dependently timed devices; in other words, two devices may be said to operate in synchronism where they are driven by two independent but identical clockworks, and they may be said to operate in synchronism also where one device is operated by a clockwork and causes the operation of the second device in step-by-step or in continuous correspondence to its own operation. In accordance with one of the features of our invention, devices such as distributors at the control station and at the substations, are independently timed and operated, the only timing connection between correspondence of events (such as local line wire connection changes) is produced at distant-points by causal means instead of by pure time measurement, we have frequently used the term time channel" on a certain conductor.

This term, as employed herein, may be defined as a specific conductor or circuit made available for a specific part of a recurring time cycle.

What is claimed is:

1. In a remote control system, a control station and a field station connected by a single line circuit, a plurality of movable devices at said field station, a plurality of indicators at said control station, impulsing means at said control station only for energizing said circuit with a series of code impulses, means eiIective only when a certain impulse of a series of impulses delivered by said impulsing means is of a given polarity to control said movable devices in accordance with the character of other impulses of said series, and means effective when said certain impulse is of the opposite polarity to control said indicators in accordance with the characters of said other impulses.

2. In a remote control system, a control station and a plurality of field stations connected by a single line circuit, movable devices at said stations, indicators at the control station for indicating the condition of said movable devices, distributors at the control station and at each field station automatically operable through recurrent cycles to transmit indications one at a time over said line circuit from each field station in turn to actuate said indicators, each in accordance with the condition of the corresponding movable device, and manually operable means at the control station for suspending said automatic operation and establishing communication with a selected field station to control the movable devices at such station over said line circuit.

3. In a remote control system, a control station and a field station connected by a single line circuit, means at the control station only for transmitting series of impulses over said line circuit, means at both stations for determining the character of said impulses, and selecting means for causing but one character determining means or the other to be eifective during the transmission of any one series of impulses from said control station. 7

4. In a remote control system, a control station and a field station connected by a single line circuit, means at the control station for transmitting series of impulses over said line circuit, movable levers atsaid control station, movable devices at said field station, manually operable selecting means in the control station which in one position causes the character of said impulses transmitted from the control station to be determined in accordance with the positions of said levers at the control station and in another position causes the character of said impulses transmitted from'the control station to be determined in accordance with the positions of said devices at the field station, a control means at said field station selectively controlled in accordance with the character of said impulses when said selecting means is in said one position, and indication means at said control station selectively controlled in accordance with the character of said impulses when said selecting means is in said another position.

5. In a remote control system, a, control station and a field station connected by a single line circuit, code transmitting means at the control station for transmitting a series of impulses of selected polarity over said line circuit, code transmitting means at the field station for governing the character of certain impulses of said series to transmit messages from said field station to said control station when a particular impulse of said series transmitted from the control station is of one polarity, means at the control station for governing the character of said certain impulses to transmit messages from said control station to said field station when said particular impulse in a series is of the opposite polarity, and manually controlled means at the control station for selecting the polarity of said particular impulse.

6. In a remote control system, a control station and a plurality of field stations connected by a single line circuit, means at the control station for transmitting code signals in one direction over said line circuit comprising a series of impulses of a given relative polarity including selected impulses of the opposite polarity, and means at each field station for transmitting code signals in the other direction over said line circuit comprising means for modifying the strength of selected ones of said impulses.

'7. In a remote control systenrof the selector type; the combination with a control office and a field station; of a single line circuit connecting said control office with said field station; impulsing means only at said control oifice for energizing said line circuit with a plurality of impulses; code sending means at said control o ifice and at said field station for determining the character of said impulses except the first; manually operable means selectively determining the character of the first impulse; and means responsive to the character of the first impulse for selectively causing either one or the other of said code sending means to be effective, whereby messages are caused to be transmitted from said control ofiice to said field station or from said field station to said control office dependent upon the condition of said manually operable means.

EL'SIE A. BLAKE, Executria: of the Estate of Eli J. Blake, De-

ceased.

ARTHUR H. ADAMS.

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