US2097794A - Centralized traffic controlling system for railroads - Google Patents

Description

'TQJ. JUDGE v CENTRALIZED TRAFF IG CONTROLLING SYSTEM FOR RAILROADS Nov. 2, 1937.

Filed July 15, 1952 2 Sheets-Sheet 1 NTO ATTORNEY Nov. 2, 1937.

T. .1. JUDGE CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed July 15, 19.32

2 Sheets-Sheet 2 INVENT ATTORNEY Patented Nov. 2, 1937 UNITED STATES ATENT OFF Thomas J. Judge, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application July 15, 1932, Serial No. 622,649

21 Claims.

This invention relates to railway traffic controlling systems, and more particularly to a system of the direct control type, as distinguished from a station selecting type of system.

It is proposed in accordance with the present invention to provide a means for controlling a remote power operated track switch by the polarity of an energy impulse impressed on a single line circuit and to select the direction of traflic over the track switch by the polarity of a second energy impulse placed on the same line circuit. It is also proposed to provide a means for indicating over a second line circuit the operation of the track switch, the clear or stop indication displayed by the signal governing movements over the track switch and the condition of a particular track section. The control means and the indicating means are to be so arranged that they may be used together in a system or, as either is complete in itself, they may be employed individually to fulfill certain requirements.

Other objects, purposes and characteristic features of the invention will appear as the description thereof progresses, during which references will be made to the accompanying drawings, in which:

Fig. 1 diagrammatically shows the apparatus in a control ofiice for governing traific movements over a single track switch and for receiving indications therefrom, and

Fig. 2 diagrammatically shows the trackway apparatus for receiving controls from and transmitting indications to the control office apparatus shown in Fig. 1.

In Fig. 1, a portion of a track diagram, which is associated with the trackway apparatus in Fig. 2, is diagrammatically shown with a movable switch point SP arranged to indicate the position of an associated track switch. This movable point SP is shown as being actuated by an electro-magnetic means, which has a normal operating electro-magnet NI and a similar reverse operating electro-magnet RI. An indicating lamp OSI is shown located in the track diagram, which may be energized to indicate the presence of a train in the track section adjacent the switch, which section is sometimes called the detector track section.

A signal control lever SGL is employed to set up the controls for wayside signals governing traffic movements over the track switch, and is operable to three positions namely west, stop and east, and operates suitable contacts which are shown in the conventional diagrammatic anner. A s t fi Q Il l ever SML is operable to two positions for setting up the controls for a switch machine employed to position the track switch in either its normal or reverse operated position. A signal indicating lamp SGI is shown associated with the control lever SGL, and this indicating lamp may be arranged within the rotary control switch or on the control panel, as desired. A bell BL is also employed at the control office to audibly indicate the entrance of a train into the detector track section and controlled as herein later described.

In Fig. 2 a section of track is diagrammatically illustrated which includes a track switch TS routing traffic to or from a diverging track section, which may be the entrance of a passing siding. A switch machine SM is employed to operate the track switch TS and this switch machine SM is in turn controlled by a two-position pol'ar relay WZ. Suitable wayside signals ES ES WS and WS are employed in the conventional manner to govern traific movements over this track switch TS and the traffic direction is governed by selectively clearing these signals ac cording to the position of a three-position polar relay SZ.

Various other relays in both the control ofiice and the field station equipment are shown in the conventional manner and it may be here mentioned that the relay C and the relay K at the control ofiice and the relays F and SZ at the wayside are of the three-position polarized type. Other neutral relays of the system both at the control ofilce and at the field station have their operating characteristics designated by the base lines thereof, that is, the relays having a heavy base line have slower operating characteristics than other relays which are not indicated in this manner.

The relay P at the field station is illustrated as being of the type disclosed in the prior application of O. S. Field, Ser. No. 452,666 dated May 15, 1930, now U. S. Patent 1,969,065 dated Aug. 7, 1934, and it may be here mentioned that this relay when energized operates an armature about a center pivot point in equally time-spaced oscillations to periodically and alternately close electrical circuits. It is, however, desired to be understood that the present system is not limited to the use of such a relay as other arrangements may be substituted, such as two neutral relays having their energizing circuits interlocked to produce alternate operation.

In tracing circuits in the description of the operation of the present system, (-1-) and will be considered opposite extreme terminals of a local source of energy, and will be considered to be a center tap or a, common potential of this energy source. Also,.in considering the operation of the polarized relays, it will be considered that the polar contacts operate in the direction in which current is considered to flow in the operating winding, that is, if current flows from left to right through the operating winding, the contacts it is assumed, are operated to the right and vice versa.

With the apparatus of the system in the posi-' tion illustrated in Fig. 1 and Fig. 2, no current flows in the control line wire L because the relay C which controls the energization of this control line circuit is de-energized. In Fig. 2, it will be noted that the track switch TS is in its normal position and the relay WP, which is arranged in the usual manner to assume a position which corresponds to the switch position, is accordingly energized to position its contacts to the left, as shown. The relay WP in this position energizes the line wire L with a polarity which positions the contacts of the polarized K relay at the control ofiice to the right over a circuit from, the center tap of the battery B at the field station, wire 6, the comon wire COM, through the windings of the polar relay K to the indication line wire L contact I of relay P, wire 8, front contact 9 of relay WP, polar contact ll] of relay WP in its left position, wire H to the terminal of battery B The switch control lever SML then being in a positionN, as shown, which corresponds to the actual normal position of the track switch, the normal switch indicating relay NK is energized over a circuit from contact l2 of relay K in its right position, wires 53 and I4, through the windings'of relay NK, wire 23, through back contact 24 of relay RK to The movable miniature switch point SP is then held in a position indicating the alignment of a route straight through the switch by the energization of the magnet NI over a circuit from back contact I! of relay RK, wire 3, front contact IQ of relay NK, wire 20, through the windings of magnet NI to Now, considering that the operator at the control ofiice desires to align a route onto the diverging track section and to clear the east bound signal ES which permits a train movement from the straight track eastward onto the passing siding, the following operations are performed. The switch lever SML is moved to the reverse position R and the signal lever SGL is, moved to the clear east bound position E thereby setting up a route on these levers which is executed or transmitted to the field location by pressing the starting button SB.

The pressing of the starting button SB completes a circuit obvious on the drawings to pick up the change relay CH, after which, a stick circuit completed by contact 28 of the lever SGL and stick contact 58 of relay CH is established to maintain the relay CH picked up. With this relay CH thus picked up, the contacts of a polarity selecting relay C are swung to the right in accordance with the polarity applied thereto by the position of the switch control lever SML. This energizing circuit for the relay C is completed from contact 29 of lever SML in its right hand position, wire 38, back contact 3| of relay SA, wire 32, front contact 33 of relay CH, wire 34, through the windings of the relay C to. (c).

The line wire L is now energized with a polarity effective to move the contacts of the relay F at the field station to theright over a circuit from, the side of battery B, wire 35, contact 36 of relay C to the right, wires 31 and 38, through the windings of relay F, line wire L through the windings of the polarized line relay F wire 39, the common line wire COM, wire 40, contact 4| of relay C to the right and back to the terminal of battery B by wire 42. This energized position of the relay F at the field station is obviously ef fective to position the contacts of relay WZ at the field station to the right in accordance with the polarity applied thereto by contact 43 of relay F to the right over a circuit including back contact 44 of relay SA I In other words, in the transmission of a switch control, the relay C being positioned in accordance with the position of the lever SML selects a corresponding polarity of energy for the control line circuit which distinctly positions the line relay F at the field station. The position of the relay F is then eifective to position the two position switch control relay WZ to correspond to the position of the control lever SML and, this relay WZ in turn is effective to energize the switch machine SM in a manner to operate the track switch TS to the selected position over either control wire RC or NC as selected by contact 45.

However, while the control line Wire is thus energized to transmit a switch control, a condition is being set up at the control office to again ener gize the control line wire L with a distinctive polarity of energy for the transmission of the signal control set up by lever SGL, and likewise at the field station a condition is being set up to sensitize the switch control relay WZ for the reception of such a control energy impulse. The time during which the energy impulse is effective to position the switch control relay WZ is marked off by the pick-up time of the relay SA at the field station which is being energized by contact 41 of .thepolarized line relay F and simultaneously, the relay SA at the control ofiice is being energized by contact 46 of relay F.

The picking up of the relay SA at the control office de-energizes the relay C at its back contact 3| which relay C in turn de-energizes the control line circuit, and, as soon as the line relay F drops, a circuit is made up to energize a second slow acting relay SAP through back contact 46 of relay F and front contact 48 of relay SA. As soon as the polarized line relay F at the field station assumes a de-energized position, contact 49 of this relay establishes a circuit through front contact 50 of relay SA to pick up a relay SC which then sticks up through a front contact of relay SA and its own front contact 52.

The drop-away time of the SA relay is sufficiently slow to allow the SAP relay to pick up and establish a circuit to again pick up the relay C in accordance with the polarity selected by the position of the switch control lever SGL, after which the F relay picks up by the following energization of the control line and front contact 46 of this relay holds up the SA relay and sticks up the SAP relay through its own front contact 53. The characteristics of these relays SA and SA must be so arranged that they do not drop their armatures when de-energized during the cumulative pick-up times'of relay SAP and their respective series line relay F and F The circuit which positions the contacts of the relay C in accordance with the east clear sig nal position of the lever SGL is made up from (c) through the windings of the relay C, wire 34, front contact 33 of relayCH, wire 32,front contact 3| of relay SA, wire 54, front contact 55 of relay SAP, wire 56, contact of lever SGL in its right position to The contacts of relay C now being in the left positions, the polarity of the control line is the reverse-of that during the switch control energization, and consequently, this polarity swings the contacts of the polarized line relay F at the field station tothe left.

The signal control relay SZ is now energized with a polarity which shifts its contacts to the left over a circuit from contact 43 of relay F to the left, front contact 44 of relay SA wire '59, front'contact 60 of relaySC, wire Bl, through the windings of relay SZ to (c) The relay WP now having its contact positioned to the right in accordance with the reverse position of the track switch TS selects the clearing of signal ES through contact 63 of relay SZ to the left, wire 64, front contact 65 of relay WP, wire 66, contact 61 to the right, through the local block signalling circuits to control the signal ES as indicated by the dotted line. Similarly, when the westbound signals are to be cleared by a reverse polarity on the control line circuit, the contact 63 of relay SZ to the right selects the westbound signals WS and WS and contacts 68 and 69 of relay WP select either signal WS or WS It is to be understood also that any one of these signals clears in this case only if the local traffic conditions permit, which is determined by the local block Signalling circuits for convenience omitted from the drawings.

It may be readily seen that an indicating circuit is made up to transmit an impulse over the indicating line circuit of a polarity which reverses the relay Kthereby dropping the relay NK at the control office and picking up the PK relay, which positions the miniature switch point SP to indicate the alignment of the diverging route over the track switch TS, all in a similar manner to that described previously in tracing the indication of the normalposition of the track switch TS. This indicating'circuit is of course effective before the signal ES clears, or as soon as the relay WP shifts its contacts to the right in accordance with the reverse position of the track switch TS.

The relay M at the field station has been shown in a conventional manner, and in practice is connected to remain energized as long as all signals are at stop, and consequently, the clear signal ES de-energizes the relay M, which completes a circuit to energize the impulsing relay P from back contact ill of relay M, front contact H of relay WP, through the relay P to Current flowing in relay P first flows through coil A and through contact 93 to the left which shunts coil B, thus attracting the armature to the right which shunts coil A instead of coil B through contact 93, which action obviously continues to produce an oscillating motion of the relay contacts. This oscillation of the armature of relay P causes its center pivoted contact I to alternately connect the indicating line wire L to the positive terminal of battery B when in one position over wire 8, front contact 9 of relay WP, polar contact It] to the right, wires 12 and 13, and then when in the other position to the negative side of battery B over wire 74, back contact 15 of relay M, wire 16, front contact ll of relay T, wire 18, front contact 19 of relay WP, polar contact 80, and wires 8| and H. These circuits made up in this manner through the impulsing relay P apply impulses of alternating polarity to the indicating circuit which oscillate the contacts of relay K at the control office to the right and left in synchronism with the armature of relay P.

Keeping in mind that the relay RK is now energized, and that the relays RK, NK, SK and SK are arranged so that their pick-up time is considerably shorter than their drop-away time, it may be seen that this alternating polarity of impulses is effective to pick up the relay SK over a circuit from contact I2 of relay K when in its right position, wires l3 and 82, through the windings of relay SK wire 83, front contact 84 of relay RK to The oscillating motion of contact !2 of relay K then picks up relay SK from contact [2 of relay K when in its left position, wires 85 and 86, through the windings of relay SK wire 81, back contact '88 of relay NK, wire 89, front contact 9!] of relay SK to The clear signal indicating lamp SGI is now energized to indicate that the signal ES has cleared in accordance with the position of the signal control lever SGL and the switch control lever SML over a circuit from front contact 9! of relay SK front contact 92 of relay SK through the filament of the indicating lamp SGI to With a clear signal thus indicated at the control office it will next be considered that an east bound train accepts the ES signal clear and enters the track section over the switch TS, thereby dropping the track relay T. The relay T dropping is of course effective to put the signal ES to stop through the local block signalling circuits (not shown), which signal going to stop picks up relay M, but it will be noticed that relay M picking up does not de-energize relay P because its energizing circuit is maintained through back contact 94 of relay T.

Although the pulsing relay P continues to operate as in the transmission of a clear signal indication, it may be seen that the line wire L is not now connected first to the positive side and then to the negative side of battery B, but is only connected to the positive side and is then de-energized for a corresponding period of time, in as much as the circuit previously traced from the negative side of battery B is interrupted at front contact 11 of relay T de-energized as well as the front contact 15 of relay M energized.

These intermittent positive impulses are effective at the control office to position the armature of relay K alternately to the left and then to the center position, and it may be here mentioned that the polarity of these intermittent impulses being selected by the contacts of relay WP at the field station is still effective to indi- 5 cate the reverse operated position of the track switch TS by maintaining relay RK energized and obviously'relay NK is de-energized. Attention is also called here to the fact that, in indicating an occupied track section with the track switch TS in its normal position as shown, these intermittent impulses are of the negative polarity which obviously oscillate the contacts of relay K from the right to the center position.

During the de-energized period between such impulses, or while the contacts of relay K are in their center position, a circuit is completed to pick up the slow releasing relay TK from through the windings of relay TK through back contact 95 of relay 8K through contact 96 of relay K when in its center position, through back contact 9! of relay SK to With the relay 'IK picked up and either relay RK or NK picked up (RK being up in this case), a circuit is then completed during the energized period or impulse to pick up relay 'IK from contact 9! of relay K in its left position, wire 98, front contact 99 of relay RK, back contact I of relay NK, wires Nil and H12, front contact H13 of relay 'IK wire I04, through the windings of relay TK to The relay TK picking up energizes a slow acting bell ringing relay BR at front contact Hi5, but during the time consumed in picking up, the bell BL is energized to give an audible signal over a circuit from front contact I05 of relay TK through back contact m1 of relay BR, through the operating winding of the bell BL to The audible signal produced by energization'of the bell BL is interrupted by the icking up of relay BR at back contact I01,- and the light 051 is then energized to indicate the occupancy of the track section over a circuit from front contact I06 of relay TK front contact lfi'l' of relay BR, wire I08 through the lamp of light CS1 to Referring now to the previous description of the transmission of a switch control and a signal controlby successive impulses, it is obvious that either a switch or a signal control may be transmitted alone as well. For example, in the transmission of a switch control alone the CH relay is in this case held up after pressing the push button SB by a stick circuit completed by back contact 62 of relay SA, and the impulse efiective to position the switch control apparatus at the field station is interrupted by the picking up of the slow acting relay SA at the control oifice which drops the relay CH at back contact 62 and de-energizes relay C at back contact 3i.

Following the picking up of relay SA, the slow acting repeatin relay SAP picks up by the line relay B being de-energized, but in the present case the relay 0 is not again energized to place a second impulse on the line wire L because the signal lever SGL is in its stop position S, and the second energizing circuit for relay C is not completed because its contact 51 is in the center position. However, in clearing a signal when a new switch control has, not been set up by the lever SML, the last transmitted control will be again transmitted in the same manner as described which of course will set up no new control at the field station thus being substantially useless except as a check on the integrity of the first transmission.

A railway centralized traffic controlling system has thus been provided which may be said to comprise a control communicating system and an indication communicating system. The control communicating system provides for the control of a remote power operate-d track switch by the polarity'of energy applied to a control line circuit comprising a single line wire and a common wire, which polarity is distinctly registered at the field station by a means arranged to retain the same until changed by the reception of an opposite control. The duration of this energization is marked off by the picking upof a slow acting relay both at the control oflice and at the field station. The picking up of the slow acting relay at the control ofiice sets up a condition for applying a second energization of a a polarity which selects the clearing of signals in the desired direction, and this second impulse is maintained as long as it is desired to clear the particular signals. Likewise at the field station, the picking up of the slow acting relay sets up a condition which sensitizes the signal clearing apparatus for the reception of thisv signal control. If no signals are to be cleared a second energization of the control circuit does not follow the picking up of the slow acting relays and the control system automatically returns to its normal at rest condition. 7

The indication communicating system provides for the indication over a single indicating line wire and the common wire of the operated position of the track switch by energizing this circuit from a source of energy located at the field station with a polarity selected according to the switch position. An indication of a clear signal is also transmitted over the same indicating circuit by intermittently applying alternate opposite polarities of energy to this circuit which is effective at the control oifice to pick up and hold up certain slow releasing relays which control the clear signal indicating means, and this alternate energization is likewise effective to retain the switch indication. A third indication which may be employed'to indicate the occupancy of a track section is made possible by applying energy impulses of a polarity corresponding to the switch position at time spaced intervals separated by corresponding periods of de-e'nergization, and these impulses, or the interrupted energization of the indicating circuit, is effective at the control office to pick up certain slow releasing relays which control an associated indicating means.

The above rather specific description of one form of the present invention is given solely by way of example, and is not intended, in any manner whatsoever, in a limiting sense. It is also to be understood that various modifications, adaptations and alterations may be applied to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention, except as limited by the appended claims.

Having thus described my invention, what I claim is:-

l. A switch and signal control means comprising a control ofiice, a distant track switch and signals for each direction of traffic thereover, a two position polarized relay at said track switch arranged to control said switch, a three-position polarized relay at said signals arranged to selectively clear said signals when energized and to put said signals at stop when deenergized, a line circuit extending from said I control office to said switch and signals, means at the control office for applying so long as said signals are to be cleared a first energization to said line circuit of a preselected polarity, means for positioning said two position relay in accordance with the polarity of said first energization, means at the control oilice for applying a second energization to said line circuit of a preselected polarity, means responsive to the deenergized condition of said line circuit between said first and second energizations for disassociating said two-position relay from said second energization, and means for positioning said three-position relay in accordance with the polarity of said second energization.

2. A switch and signal control means comprising a control ofiice, a distant track switch and signals for each direction of trafiic thereover, a

two-position polarized relay at said track switch arranged to control said switch, a three-position polarized relay at said signals arranged to selectively clear said signals when energized and to put said signals at stop when deenergized, a line circuit extending from said control oflice to said switch and signals, means at the control office for applying a first energization to said line circuit of a preselected polarity, means for positioning said two-position relay in accordance with the polarity of said first energization, means at the control oflice for de-energizing said line circuit after said first energization, means at the control office for applying a second energization to said line circuit of a preselected polarity, means for disassociating said two-position relay from said second energization and means for positioning said three-position relay in accordance with the polarity of said second energization only if said line circuit is deenergized between said first and second energizations.

3. An indicating system comp-rising a control oflice, a distant track switch and associated signals controlled from said control oifice, an indicating line circuit connecting the control ofiice and the switch and signal location, means at the switch and signal location for energizing said indicating line circuit with a polarity corresponding to the operated position of said track switch, responsive means at the control office for displaying the track switch position according to the polarity of said line circuit energization, means at the switch and signal location for applying successive energy impulses of alternately opposite polarities to said indicating line circuit upon clearing of any of said signals, and means at the control oflice responsive to said impulses of alternate polarity in a manner to display an indication of a clear signal.

.4. An indicating system comprising a control ofiice, a distant track switch and associated signals, an indicating line circuit connecting the control ofiice and the switch and signal location, means at the switch and signal location for energizing said indicating line circuit with a polarity corresponding to the operated position of said track switch, responsive means at the control office for displaying the track switch position according to the polarity of said line circuit energization, means at the switch and signal location for applying successive energy impulses of alternatelyopposite polarities to said indicating line circuit upon clearing of any of said signals, and means at the control ofiice responsive to said impulses of alternate polarity in a manner to display an indication of a clear signal and to retain the displayed indication of said track switch position.

5. An indicating system comprising a control oifice, a distant track switch and associated si nals, an indicating line circuit connecting the control ofiice and the switch and signal location, means at the switch and signal location for energizing said indicating line circuit with a polarity corresponding to the operated position of said track switch, responsive means at the control ofiice for displaying the track switch position according to the polarity of said line circuit energization, means at the switch and signal location for applying successive energy impulses of alternately opposite polarities to said indicating line circuit upon clearing of any of said signals, means at the control ofiice responsive to said impulses of alternate polarity in a manner to display an indication of a clear signal and to retain the displayed indication of said track switch position, means, at the switch and signal location for intermittently interrupting said switch position indication energization of said indicating line circuit when a train occupies said track switch, and means at the control ofiice responsive to said intermittent energization in a manner to display anindication'of the track switch occupancy and. to retain the displayed indication of said track switch position.

6. In combination, a control oifice, a distant track switch and signals for each direction of traffic thereover, a control line circuit extending from the control oifice to the track switch location, means for controlling the track switch by the polarity of a first energization applied to said control line circuit, means for selectively clearing the signals in either direction by the polarity of a second energization applied to the control line circuit, an indicating line circuit extending from the control ofiice to the track switch location, means for indicating at the control office the operated position of the track switch by the polarity of energy applied to the indicating line circuit, means for indicating at the control, office the clearing of any one of said signals by applying impulses of alternating polarity to the indicating line circuit, and means for indicating at the control ofiice the presence of a train in a track section associated with said track switch by applying time-spaced impulses to the indicating line circuit.

7. In combination, a control office, a distant track switch and signals for each direction of traific thereover, a control line circuit extending from the control office to the track switch location, means for controlling the track switch from the control oifice by the polarity of a first energization applied to said control line circuit, means for selectively clearing the signals in either direction from the control oifice by the polarity of a second energization applied to the control line circuit, an indicating line circuit extending from the control oiiice to the track switch location, means for indicating at the control ofiice the operated position of the track switch by the polarity of energy applied to the indicating line circuit, means for indicating at the control office the clearing of any one of said signals by applying impulses of alternating polarity to the indicating line circuit, and means for indicating at the control ofiice the presence of a train in a track section associated with said track switch by applying time-spaced impulses to the indicating line circuit of a polarity effective to also indicate the operated position of the track switch.

8, In combination, a control office, a distant field station, a track switch and directional sighals associated with the field station, a control line circuit connecting the control ofiice with the field station, means for controlling the operation of said track switch and for selectively clearing said signals in either direction from the control ofiice by respective successive energizations of a preselected polarity applied to said control line circuit, anindicating line circuit connecting the control office and the field station, means for indicating at the control office the operated position of the track switch by the application of a distinctivepolarity of energy to said indication line circuit, an oscillating contacting means at said field station operable to energize said indieating line circuit with alternate opposite polarities, means for indicating a clear signal at the control office by operating said contacting means and applying both of said polarities alternately to said indicating line circuit, and means for indicating train occupancy of said track switch at said control ofii'ce by operating said contacting means and applying only one polarity intermittently, saidione polarity being distinctive of the operated position of the track switch.

9. In an indicating system, a control ofiice, a distant field station, a track switch and directional signals associated with said track switch at the field station, an indicating line circuit connecting the control office and the field station, means for indicating at the control ofiice theoperated position of the track switch by the application of a distinctive polarity of energy to said indication line circuit, an oscillating contacting means at said field station operable to energize said indicating line circuit with alternate opposite polarities, means for indicating a clear signal at the control office by operating said contacting means and applying both of said polarities alternately to said indicating line circuit, and means for indicating train occupancy of said track switch at said control ofiice by operating said contacting means and applying only one polarity intermittently, said one polarity being distinctive of the operated position of the track switch.

10. In a railway centralized trafiic controlling system, a control office, a distant field station, a line circuit connecting said control office with said field station, means for indicating at the control office the condition of one trafilc controlling device at said field station by the direction of current in said line circuit, means for indicating a condition of a second traffic controlling device by causing periodic reversal of the direction of current flow in said line circuit, and means for indicating the occupied condition of a track section at said field station by causing intermittent current to fiow in said line circuit.

11. In a railway centralized traffic controlling system, a control office, a distant field station, a line circuit connecting said control office with said field station, means for impulsing said line circuit at said field station, means at the field station for selecting alternate opposite polarities for said impulses to indicate one condition of trafiic controlling devices at the field station, means for selecting alternate impulses of a single polarity to indicate another condition of the trafiic controlling devices, and means -for at times stopping said impulsing means to indicate a third condition of the trafiic controlling devices.

12. In a railway centralized trafiic controlling system, a control point, a distant group of traflic controlling devices, two line circuits connecting the control point and the group of traflic controlling devices, means for controlling a plurality of said traflic controlling devices from said control point by the respectively polar characteristics of a plurality of successive energizations of preselected polarities applied to one of said line circuits, and means for indicating at the control point the condition of said various traffic controlling devices by the polarity of energization and combinations of energy impulses applied to theother of said two line circuits.

13. In combination, a central ofiice, a distant wayside location on a railway system, two levers in said central office, two polar relays at said wayside location, a line circuit connecting said office and wayside location, and means for causing said line circuit to be temporarily energized by a polarity of current dependent on the position of one of said levers and then be continuously energized by a polarity of currentdependent on the position of the other of said levers and including other means for causing one of said ree lays to be temporarily energized in accordance the position of one of'said levers and to be continuously energized in accordance with the position of the other of said levers until manually released, and means controlling said track switch in accordance with said momentary energization and said signals in accordance with said continuous energization.

15. Ina traific controlling system, a control office, a track switch and signals governing trafilc thereover, a line circuit connecting said control ofiice and said track switch, means at said control office for impressing a distinctive momentary and a distinctive maintained energization upon said line circuit for respectively controlling said switch and signals, means responsive to the distinctiveness of said energizations for effecting the control of said switch and said signals, and means responsive to the duration of said maintained energization for said signals to continue the distinctive control of said signals as long as such energization is maintained.

16. In a railway traffic controlling system, a control office, a track switch and signals governing traffic thereover, a line circuit connecting said control ofiice and said track switch, two levers in said control ofiice, a contact which can be manually actuated in said control office, means efiective upon the actuation of said contact for causing said line circuit to be momentarily energized in accordance with the position of one of saidlevers and to be thereafter continuously energized in accordance with the position of the other of said levers until manually restored, means controlling said track switch in accordance with said momentary energization and said signals in accordance with said continuous energization, and means including said other lever for restoring said line circuit to a normally deenergized condition.

17. In a railway traffic controlling system, a control office, a track switch and signals governing trafiic' thereover, a line circuit connecting said control office and said track switch, a switch control lever in said control oflice, a signal control lever in said control oifice, means causing said line circuit to be'momentarily energized in accordance with the position of said switch control lever and thereafter to be continuously energized in accordance with the position of said signal lever so long as and only so long as said signal lever is in a clearing position, and means controlling said track switch in accordance with said momentary energization and said signals in accordance with said continuous energization.

18. In a railway traffic controlling system, a control oifice, a track switch and signals governing traffic thereover, a line circuit connecting said control office and said track switch, a switch control lever in said control office, a signal control lever in said control office, means causing said line circuit to be momentarily energized in accordance with the position of said switch control lever and thereafter to be continuously energized in accordance with the position of said signal lever so long as and only so long as said signal 75 lever is in, a clearing position, means for controlling the track switch in accordance with the momentary energization, and means for controlling said signals in accordance with the continuous energization so long as and only so long as such energization continues.

19. A switch and signal control means comprising a control ofilce, a switch control lever, a signal control lever, a distant track switch and signals for each direction of traffic thereover, a two position polarized relay at said track switch arranged to control said track switch, a three position polarized relay at said signals arranged to selectively clear said signals when energized and to put said signals at stop when deenergized,

a line circuit extending from said control office to said switch and signals, means at the control ofiice for applying a first energization to said line circuit of a preselected polarity in accordance with the position of said switch control lever, means for positioning said two position relay in accordance with the polarity of said first energization; means at the control ofiice for deenergizing said line circuit after said first energization, means at the control office for applying a second energization to said line circuit of a preselected polarity in accordance with the position of said signal control lever independently of said switch lever, means for disassociating said two position relay from said second energization, and means for positioning said three position relay in accordance with the polarity of said second energization only if said line circuit is deenergized between said first and. second energizations, whereby said track switch cannot be controlled while said signals are cleared.

20. In a railway traffic controlling system for railroads, a control ofilce, a track switch and signals governing traffic thereover, a line circuit connecting said control office and said track switch, two control levers in said control oiifice each being capable of assuming a plurality of different conditions, means causing said line circuit to be momentarily energized with one polarity or the other in accordance with the condition of one of said levers and to be continuously energized with one polarity or the other in accordance with the condition of the other of said levers until its condition is manually changed, and means controlling said track switch in accordance with the polarity of said momentary energization and said signals in accordance with the polarity of said continuous energization.

21. In combination, a line circuit connecting a central office and a field station, a railroad track switch and signals governing traffic thereover at the field station, switch position transmitting means at the field station for applying energy of one polarity or the other to said line circuit depending upon the position of said track switch, a detector track section associated with said track switch, means for periodically interrupting the energy applied by said switch position transmitting means when said detector. track section is occupied, means for periodically reversing the polarity of the energy applied by said switch position transmitting means when any of said signals are cleared provided said detector track section is unoccupied, and means at the control ofiice distinctively controlled by the energy applied to said line circuit to thereby indicate the position of said track switch and the conditions of said signals and detector track section.

THOMAS J. JUDGE.

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