US1733985A - Interlocking system for railroads - Google Patents

Description

Oct. 29, 1929. w. s. HENRY INTERLOCKING SYSTEM FOR RAILROADS 2 Sheets-Sheet Filed 001;. 5. 1926 ATTORNEY 2629M. OE 6 9622 2.

INVENTOR M fliu/ Oct. 29, 1929. w, s, RY

INTERLOCKING SYSTEM FOR RAILROADS 2 Sheets-Sheet Filed Oct. 5. 1926 VENTOR' FL FL E v .IL F

Patented Oct. 29, 1929 WILLIAIVI S. HENRY, OF ROCHESTER, NEW YORK, ASSIGNOR T0 GENERAL RAILWAY SIGNAL COMPANY, 015 RGCHES'I'ER, NEW YORK INTERLOCKING SYSTEM FOR RAILROADS Application filed Gctober 5, 1926. Serial No. 139,641. I

This invention relates to interlocking sys terms for railroads, and more particularly to features of cross protection and indication for such systems.

In order to simplify the disclosure and de scription of the present invention the term trailic controlling device is used to signify any one of the devices used for controlling the movement of traffic on a railroad such as, a wayside signal, a switch machine, a power operated derail, a power operated movable point frog, and the like.

In one type of central energyallelectric interlocking system, commonly known as a dynamic indication system, the necessary interlocking between the traffic controlling devices may be said to be obtained primarily by the mechanical interlocking between levers controlling said devices and the dynamic indication mechanism, and associated parts, which assure that the position of the lever shall correspond with the position of the traffic controlling device. This dynamic indication type of interlocking system, being well known, need not be discussed in detail; but to facilitate an understanding of the improvements of this invention, it is desirable to note that the dynamic current, in addition to operating the indication mechanism of the levers, also serves to snub the motor of the switch machine, and furthermore checks the integrity of the circuit through the cross protection relays.

Generally speaking, the principal objects of the present invention are to simplify and improve the dynamic indication type of allelectric interlocking system, more particularly by making provisions to permit omission of the indication mechanism on the levers, and associated parts, such as the safety magnet, indication selector, which have been found essential to guard against improper operations of the-indication mechanism, while at the same time retaining a reliable check upon the cross protection relay, and utilizing the dynamic current for snubbing. More specifically, it is proposed to eliminate indication positions on the levers, permitting their unrestrained movement, eX-

cept as they may be locked by detector locking, or directly by an electrical lever lock, or

indirectly through the mechanical locking, in case conflicting levers have not'been operated or their respective trai'fic controlling devices responded, several organizations and. arrange ments in this respect being possible. In order to indicate in the tower the existing posi tion of the particularly the position of switch points, to permit interlock or inter-control with-conflicting levers,;it is proposed to employ a re lay in the tower, commonly known as an S. S. relay, energized over a circuit, preferably polarized, which is controlled by contacts operated in accordance with the position of the switch or other traffic controlling device. To check the integrity of the cross protection circuit, a dynamic current responsive device is connected in this circuit; and its contacts, which are included in the energizing circuit for the S. S. relay, and which are automatically opened each time a lever is moved or its corresponding traific controlling device is operated, will not close and permit energization of the S. relay, unless dynamic current actually flows through the cross protect-ion circuit. l f One advantageous feature of the improved type of system just described in general terms is that a plurality of'switches or signalscan conveniently be controlled from a singlelever, while retaining the advantages'of the dynamic indication central energy type of system.

Other objects, purposes and characteristic features of the invention will in part appear as the description progresses and in part be traflic controlling devices, more electrically operated to its inactive or abnormal position.

Referring to Fig. 1, an application of the present invention has been illustrated in the control circuits for two switch machines controlled by a single lever L. This lever L is one of a large number of levers in an interlocking plant, where conflicting levers are mechanically interlocking through a suitable interlocking frame including horizontal locking bars which are operated or locked, as the case may be, by vertically operated locking tappets, of which the tappet 10 only has been illustrated. These tappets, as shown, are moved vertically in response to horizontal movement of the levers in any suitable way, as by a roller moving in a slot. It may be explained here that, in the system of this invention, this mechanical interlocking between levers is retained,though not absolutely essential in some forms of the invention for safety, to determine the sequence of operation of the levers, so as to avoid traffic delays on account of failure of the operator to move the number of levers and in the sequence required to set up the desired route; It should be understood, however, that this mechanical interlocking between levers, particularly between switch and signal levers, may be utilized to prevent operation of a lever, for instance a switch lever, until other conflicting levers have been operated and their respective traffic controlling devices responded.

In the particular arrangement illustrated in the drawings, a cross-over track GO has been illustrated connecting a west bound track W and an east bound track E, this crossover track being provided to permit trains to be transferred from the east bound to the west bound track, or vice versa, when required. Since the switches of this cross-over track'CO should always assume corresponding positions it is feasible and desirable to control the two switch machines SM and SM by the same lever. At the east end of the cross-over have been illustrated a west bound main signal S and a diverging route signal S and at the west end of this crossover have been illustrated on east bound main signals and a diverging route signal S. There are of course provided additional distant signals which have for convenience been omitted.

Each of the switch machines are controlled by control circuits including a cross protection relay, and each of these relays CPR and CPR are constructed to be actuated if direct current flows through. the winding thereof in one direction but which will not respond it direct current flowsin the other direction. These relays preferably include a permanent magnet 11, soft iron cores 12 and 13, a soft iron armature 14, contacts 15 and a coil 16 contained on the core 12. In this construction the flow of direct current in one direction in coil 16 causes additional magnetic flux to pass through core 13 and armature 14 to hold the contacts 15 closed; whereas the flow of direct current in the opposite direction in coil 16 robs this core 13 and armature let of magnetic flux supplied by the permanent magnet 11 and causes the armature to drop and complete a magnetic circuit through core 12. These cross-protection relays are therefore polar stick relays which if once operated to open their contacts 15 must be mechanically reset.

In each of the control circuits of the switch machines SM and SM is included a dynamic current responsive relay of the mechanical stick or toggle type. designated D and D and have their armature 20, held in either the raised position, or the lowered position against the stop 28, as

the case may be, by the toggle mechanism ineluding the rotatable perforated post 21, a

crank arm 22, a guide pin 23, and aspring 24 V on said guide pin for holding the crank 22, in one or the other of its extreme positions. It will readily appear that movement of the lever L from either extreme position to the opposite extreme position causes the armatures 20, to be forced to their lower position by the projections on the push rod 25, which rod is returned to its normal position by a spring 26.

In view of the fact that the various devices shown for the purpose of illustrating applicants invention have been shown in accordance with established convention it is believed expedient to now consider the operation of the system embodying applicants invention. Let us therefore assume that it is These relays have been desired to operate both of the switches 18 and 19 to the diverging route position, so as to permlt a train to take the cross-over track from one of the main tracks to the other main track. It will at once appear that the lever L cannot be moved until all of the conflicting levers assume a non-conflicting position, this by reason of the mechanical interlocking mechanism including the locking tappet 10. If now all of the conflicting levers have been moved to the proper position, the lever is free to be moved as far as the mechanical interlocking is concerned. Also if there is no train standing on any of the detector track circuits associated with the main tracks and crossover track, or on the approach locking track circuits if such are used, all depending on the exact construction of the detector and approach locking arrangement, the various track relays such as T T, T and T will assume their energized positions. Also, if all of the various conflicting traffic controlling devices assume the proper position and have responded to the last change in the position of their control lever, their corresponding indication relays and dynamic current responsive devices will assume the proper. position to unlock the lever L. These indication relays and dynamic current responsive devices have been generally illustrated by the relay IE and the dynamiccurrentresponsive devices D and D respectively. In this event the energizing circuit for the lock magnetLM which constitutes a lever lock is energized through a circuit readily traced in the draw.- ings and the lever L'maybe moved to the reverse position. 7 r

In the case where a conflicting traffic controlling device constitutes a signal, its control lever may beprovided with a lever lock magnet, which permits it only tobe moved to the half normal position, and this magnet may be controlled by a circuit including a contact on the signal closed when the signal is at stop, all as Well understood by those skilled in this art. By this arrangement this signal lever through the mechanical interlocking will afford the necesasry locking.

The movement of the lever L to the reverse position causes the armatures of the dynamic current responsive relays D and D to assume a position to open their contacts 27 and 27 these contacts being held open by the toggle springs 24. With the lever L assuming the reverse position the following circuit is completed for the switch machine SM :-begln' ning at the battery 30, wiresv 31, 32, 33, 34, contacts -36, wire 37, reverse wire R contacts 3940, wires 41 and 42, armature of the motor M wires 43 and 44, contacts 4546, wire 47, field winding of the motor Iv wires 48, 49 and 50, contacts 15 0f the cross protection relay CPR wire 51', contacts 15 of the cross protection relay CPR wire 52, back to battery 30. Anothercircuit similar to the one just traced is completed for the switch machine SM which circuit need not be specii'ically traced. The completion of these circuits causes the motors M and M to be operated, thereby moving the track switches 18 and 19 to the cross-over position; lVhen the motor M has completed the stroke of the switch machine SM thecontacts 40 and 46 of this switch machine will be quickly moved to the dotted position .and by such movement will reverse the relation of the connections between the field and the armature of the motor il thereby causing a snubbing current to be generated which retards or brakes the motor.

This current flows in the following circuit and returns the armature 20 of the dynamic current responsive relay D to its raised position: beginning at the, armature of motor M wire 42, contacts 5846, wire 54, field of motor 1/ wires 48, 49 and 55, winding 16 of the cross protection relay CPR}, wire 56, winding of the dynamic current responsive relay D wire 57, contacts 5859, wire 60, normal wire N contacts 6140, wires 43 back to the armature of the motor M This dynamically generated snubbing ourrent flows through the coil 16 of the cross protection relay CPR in such'a direction as not to operate armature 14 or" this relay, and flows through the dynamic current responsive relay D to cause the armature 20 to as sume the-raised position so as to close the contacts 27 In a similar way the operation of the motor M and its 'snubbing action causes the armature-20 oi the dynamic current responsive relay D to assume its raised position. 1 r

With the switch machine 8M and SM assuming the reversed position, the indication relay IE and IE will assume the reversed position, because-the contacts as as sociated with the switch machines 8M and SM have reversed the polarity of the current applied to these indication relays. By reason of the simplicity of the circuits for these inch-- cation relays Ilt an'dIR itis believed unnec- J essary to trace the circuits therefor. It should,

however,l e noted that the circuit for indi j cation relay 1R includes in series therewith the contact 27 of dynamic current responsive.

relay D and the circuit for the indication relay 1R includes in-series therewith the contact 27 oi the dynamic current responsive relay D In other words, the relays 1B and lR cannot assume an energized position unless the contacts ottheir corresponding dynamic current responsive relays have been closed. It may be pointed out at this time that the contact 62 is open so long as the switch ma; chine with which it is associated is unlocked, this switch machine preferably being one of the type shown inthe patent to l-lowe No. 1,466,903. f I

The switches 18 and 19 now having been moved to the cross-over or diverging route position and the indication relays 1B and 1B having assumed their reverse position, electri cal energy is applied to the wire 65 from a suitable source of energy having aterminal B through contacts 66 and 6'? in their dotted position. .This wire65 preferably leads to the levers of diverging route signals such as the signals S and S shown, from which it appears that these diverging route signals cannot'be cleared until'the switches 18 and 19 assume the cross-over position. Likewise, it is apparent that the main signals such as the signals S and S cannot be cleared until the terminal B is connected to the wire 68 which leads to the levers of the main signals, and which requires the contacts 66 and 59 to assume their normal right hand position, in which they have been shown. By examining thecircuit arrangement'oit the switch machines SM and SM it will readily appear that thecross protection relay CPR is connected in multiple withthe motor M for allcaseswhere it is possible for unauthorized current to be applied to this motor, and that the cross protection relay CPR in like manner is connected in multiple with the motor M and that this is true regardless of whether these switch machines assume the normal straight track position or the reverse diverging route position. This arrangement of devices and circuits is resorted to so that if current should be applied to one or the other of these motors accidentally by reason of a cross, or the like, this current would be permitted to flow through two paths, one of which is of a medium resistance, namely that of the motor of the switch machine, and the other of which is of extremely low resistance, namely that including the dynamic current responsive relay D and the winding 16 of the cross protection relay in series, so that a large part of the current due to such cross will flow through these two relays. Also, it should be noted that this flow of current would be from wire 56 toward wire 55 through the coil 16 of the cross protection relay. Currentflow in this direction causes the cross protection relay to respond and open its contact 15, thereby disconnecting the negative side of the battery 30 from the common return wire 49.

In practice it has been found that this will occur before the motor of the switch machine has had time to start moving the switch.

The partial cross protection branch circuit just mentioned, includingthe dynamic current responsive relay D and the cross protection relay CPR, is in multiple with the motor of the switch machine, and therefore if this branch circuit should accidentally become open, the cross protection relay CPR would not respond to this flow of unauthorized current, and for this reason it is important that the continuity of this branch circuit be checked repeatedly.

In accordance with the present invention, the continuity of this branch circuit is checked for each operation of the traflic controlling device, which device in the particular arrangement shown comprises a switch machine, by requiring a flow of snubbin-g or dynamic current in this branch circuit before the circuit for the corresponding indication relay is completed, so that the flow of snubbing current not only retards the motor but also manifests the integrity of the branch circuit including the cross protection relay. This dynamic snubbing current also manifests that the traflic controlling device has responded to the last movement of the control lever. In this connection it is desired to point out that for those traflic controlling devices in which only one position thereof need be indicated, such as a signal for instance, (the danger condition of which only need be indicated at the tower), and wherein the indication relay may be a two position relay, the indication circuit leading to the traflic controlling device may be entirely dispensed with and the dynamic current responsive relay itself may be used as an indication relay, or it may be connected to control an indication relay either by itself or in conjunction with other relays, all as obvious to those skilled in the art of inter locking after reading the foregoing description.

Movement of the lever back to its normal position in which it has been shown, establishes the normal circuit including the wire N which is substantially the same as the reversed circuit including the wire R and for this reason it is deemed unnecessary to specifically trace the normal circuit or the normal branch circuit which as shown in the drawing includes the dynamic current responsive relay and cross protection relay in series.

If the invention illustrated in Fig. 1 is applied to the traflic controlling device having only one important position, such as a signal as shown in the patent to Benedict No. 1,533,357, the lever L would only be provided with one notch for operating the push rod 25,'this notch being so positioned and constructed that the push rod 25 is depressed when the lever is moved to a position to clear the signal, but is not depressed when the lever is returned to normal. By this arrangement the dynamiccurrent responsive relay D would be returned to normal by snubbing current when the signal is. returned to the normal danger position. 7

As readily appears from thedrawing, the present invention permits any number of traflic controlling devices to be operated or controlled by the same lever, because each traflic controlling device may have its own indication relay and these indication relays may have their contacts so connected that conflicting traflic controlling devices may be prevented from being operated until all of the trafiic controlling devices controlled by such single lever have responded. Also, each of these traffic controlling devices, although controlled by a single lever, may have their individual circuits provided with cross protection relays; and the integrity of the branch circuit including such relay is checked for each operation of the trafiic controlling device.

In the present invention the dynamic current responsive device serves two important functions (1) it manifests after each operation of the trafiic controlling device that the branch circuit including thecross protection relay is intact, and (2) it manifests that the traflic controlling device has actually responded to the last change in the position of the lever for controlling such device, because the contact of such dynamic current responsive device is opened during each lever movement and dynamic current must have flowed and reclosed such contact. In addition to these features the circuit for the snubhing current permits the motor to In order to indicate whether or not the switch machines SM and SM assume anextreme position and whether the dynamic current responsive relays D and D assume the attracted or retracted position indication lamps P and P have been provided. Each these lamps is energized when its corresponding switch machine assumes an extreme position and its corresponding dynamic current relay is in the retracted position as is obvious from Fig. 1 of the drawings.

In F fig. 2 of the drawingshas been illustrated a layout including two switches operated by switch machines which are controlled in exactly the same manner as are the switch machines shown in Fig. 1, except that the dynamic current responsive relays, which have been designated DS and DS in Fig. 2 of the drawings are electrically operated to their abnormal or non-indicating position, whereas the dynamic current responsive relays D and D of Fig. 1 are mechanically operated to their non-indicating positions. Referring to these two drawings it should be noted that the-coil 7 O of the dynamic current responsive relay D8 is connected in series with the coil 16 of the cross protection relay CPR exactly in the same way as is the winding of the dynamic current responsive relay D in Fig. 1 of the drawings. Also, it should be noted that the coil'71 of the dynamic current responsive relay DSF (see Fig. 2) is connected in thewire 33 of the circuit ar rangement shown in Fig. 1, and for this rea son the wires leading to and from the coils 71 of the dynamic current responsive relay DS have been designated 33 and 83 in Fig. 2 of the drawings, In this connection, it should be noted that if the contact 27 a of the dynamic current responsive relay D8 is in the left hand position it will shunt the winding 71 i this relay. The construction of a device suitable for these dynamic current responsive relays BS and D8 of-Fig. 2 is shown in the patent to W. K. Howe, No. 1,550,611, dated August 18, 1925. I

In order to more clearly understand how the dynamic current responsive relay o'fFig.

2 is caused to assume its abnormal position upon movement of the lever, and how move ment of this contact is assured before the traffic controlling device can respond to ,a change in the position of its control lever,

it is deemed expedient to go through the va-- rious steps of operating a traffic controlling device to the reverse positionand receiving an indication that it has been operated to such position. Referring to Fig. 2 let us assume that'the various indication relays'IR, the various track relays T T T, T and the various dynamic current responsive relays DS and DS all assume a position to lose theircontacts so that the lock magnet LM of the lever L is energized and permits 7 movement of the lever from its normal to its reverse position. I

Movement of the lever L to its reverse position causes the'following circuitto be completed: beginning at the battery 30, wires 31, 82, and 33, winding 71, of the dynamic current responsive relay DS wire 33", wire 34, contacts 3586, wire 87, reverse wire R contacts 39 40, wires 41 and 42, armature of the motor M wires-43 and 44, contacts '45-46, wire 47, field winding of the motor M wire 48, common return wire 49, wire 50,

contact 15 of the cross protection relay CPR wire 51, contact 15 of the cross protection relay CPR wire 52 back to the battery 30.

The completion of this circuit causes the current to flow throughthe magnet coil 71 of the dynamic current responsive relay DS but byflreason' of the high resistance of the coil 71 the motor M will not-be operated the instant thiscircuit is completed. The flow of current in the coil 71 will however, cause the contacts 27 of the mechanical stick dynamic current responsive relay to be shifted to the left hand position where it will be frictionally and latchingly held, and this shifting of the contact 27 causes the coil 71 to he shunted, thereby permitting a'heavier current flow which will operate the motor M? of the switch machine SM Operation of the switch machine SM to, its cross-over position, causes the contacts 62 to shift thereby reversing the polarityra'pp'lied to the indication circuit, the indication relay IE will however remain in its de-enrgized' and 46 are very quickly shifted to the reverse position, whereby the relation of the field to the armature of the motor M is reversed, thereby causing the motor to act as a generator and causing a heavy snubbing current ,to flow in the following circuit :beginning at the armature of the motor M wire 42, contacts 53-46, wire 54, field winding of the motor M wire 48, commonreturn wire 49, wire '55, winding 16'of the cross protection relay CPR wire 56, winding" of the dynamic current responsive relay DS wire 57, contacts 5859, wire 60, normal wire N contact 61-40, vwire 43, back to the armature of the motor M reverse, or

- SM to be operated in the same way and in turn cause the indication relay IE to assume the reverse position, so that electrical energy is applied to the levers of diverging route signals in a manner as explained in connection with Fig. 1 of the drawings.

In order to indicate to the operator when the traiiic controlling device has responded to a change in the position of the lever (see Fig. 2) the indicatina lamps J and K may be used if desired; Ihese lamps J and K are respectively energized when the dynamic current responsive relay DS assumes the normal and abnormal position, respectively, these energizing circuits being readily traced and include contact 74 of the relay DS and the terminals B and C of a suitable source of current. Similar indicating lamps J 2 and K are shown in connection with the relay D8 It is thus noted that in the arrangement shown in Fig. 2 of the drawings, movement of the contacts 27 of the dynamic current responsive devices DS and DS to the left hand abnormal position in response to movement of the lever is assured, because the switch machine motors cannot operate so long as the coil 71 of high resistance is connected in series therewith, and the fact that this coil 71 is shunted by the contact 27 is proof that this contact 27 a has been shifted to its abnormal position. The features of cross protection, checking of the cross protection branch circuit and checking of the indication of the arrangement shown in Fig.2 is identically the same as that of the arrangement shown in Fig. 1, and for this reason a further discussion of the arrangement shown in Fig. 2 is deemed unnecessary. It may, however, be pointed out that the arrangement shown in Fig. 2 has certain advantages in that the dynamic current responsive devices are self contained and need not be mechanically connected with the lever with which they are associated. Also, it may be pointed out that, if the arrangement shown in Fig. 2 is employed for operating a signal, the coil 71 would be connected in the operating wire of a signal circuit such as shown in the patent to Benedict above referred to, and the coil would be substituted in the circuit for the indication magnet I'M in said patent.

Having thus shown several embodiments of the present invention applied to a combination wherein two switch machines are op erated by the same lever,it is desired tobe understood that this has been done to bring out the advantages of the present invention which makes it especially well applicable to an arrangement wherein a plurality of traftic controlling devices are controlled by a single lever, but that the invention may be applied to an arrangement where a single trafiic controlling device is controlled by a lever with substantially the same advantages. Also, it is desired to be understood that the invention is applicable to control circuits for controlling anysuitable traffic controlling device irrespective of whether it has only one essential position, as does a though several specific arrangements have been shown, the arrangements shown are susceptible of modification and adaptation to the particular interlocking problem encountered without departing from the scope of the invention.

What I desire to secure by ent, is

1. In an interlocking system for railroads, a traiiic controlling device including a motor for operating the same, a lever for applying operating current to said motor, an indicating device for indicating the condition of said trafiic control device, an indicating circuit for energizing said indicating device, a circuit for snubbing said motor completed when said motor has completed the operating stroke of said traffic controlling device, and means for breaking said indicating circuit when said lever is operated and maintain it broken unless current flows in said snubbing circuit after said motor. has completed such operating stroke.

2. In an interlocking system for railroads, a traffic controlling device including a motor for operating the same, a lever for applying operating current to said motor, an indicating device for indicating the condition of said trafiic controlling device, an indicating circuit for energizing said indicating device, a circuit for snubbing said motor completed when said motor has completed the operating stroke of said traflic controlling device, and dynamic current responsive means containe in said snubbing circuit and having contacts closed in response to the flow of snubbin g current in said snubbing circuit and opened in response to operation of said lever, said contacts being contained in said indicating circuit, whereby said indicating opened at said contacts upon operation of said lever and is reclosed in response to the flow of snubbing current in said circuit.

3. Aninterlockingsystem for railroads, the combination with a single lever, of two motor operated traflic controlling devices controlled by said lever by independent control circuits, a dynamic current responsive device in each of said control circuits which assumes an energized condition in responseto current dy- Letters Patcircuit is namically generated by said motor after said motor has completed the operating stroke of said traffic controlling device, a pair of contacts for and controlled by each of'said'dynamic current responsive'devices, and a circuit for a conflicting traflic controlling device including both of said pairs of contacts.

4. In an interlocking svstem for railroads, the combination with a single lever, of two motor operated traffic controlling devices controlled by said lever by independent control circuits, a dynamic current responsive device in each of said control circuits, each device assuming an energized condition in response to current dynamically generated by the corresponding motor after such motor has completed the operating movement'of said trailic control device, an indicating relay for each of said traffic control devices controlled by an indicating circuit controller located at and responsive to the operated condition of such traflic controlling device, contacts controlled by one of said dynamic current responsive devices contained in one of said indicating circuits, and contacts controlled by the other of said dynamic current responsive devices contained in the other of said indicating circuits.

5. In an interlocking system for railroads, the combination with a traflic controlling de vice, a motor for operating said traiiic controlling device, a cross protection relay at times connected in a branch circuit in multiple with said motor, an indicating device for indicating the operated position of said traffic controlling device controlled by an indicating circuit including a pair of contacts controlled by said traliic controlling device, dynamic current responsive'means contained in said branch circuit for checking the integrity of said branch circuit, and contacts controlled by said dynamic current responsive means for interrupting said indicating circuit unless said dynamic current responsive means responds after operation of said motor to snubbing current flowing in said branch circuit, whereby the integrity of said branch circuit is checked during each operation of said motor, and whereby the completion of the indicating circuit requires. closure of the contacts controlled by said trafiic' controlling device and closure of the contacts controlled by said dynamic current responsive means.

6. In an interlocking system for railroads, the combination with a trafiic controlling device, a motor for operating said traffic controlling device, a cross protection relay at times connected in a branch circuit in mul-' tiple with said motor, an indicatingdevice for indicating the operated position of said trafiic controlling device controlled by an indicating circuit including a pair of contacts controlled by said trafiic controlling device, another pair of contacts in said indicannot assume its energized condition unless the contacts controlled by said trafiic' con-' trolling device are closed and a dynamic currenthas been flowing insaid another coil' since the last operation of saidmotor.

7. In an interlocking system for railroads,

the combination with a traffic controlling device, a motor for-operating said traffic controllingdevice, a cross protection relay at times connected in a branch circuitin multiple with said motor, an indicating device for indicating the operated position of said traiiic controlling device'controlled by an indicating circuit including a pair of contacts I controlled by said traffic controlling device, another palr of contacts n sa d indlca'tmg circuit, a coil for opening said another pair of contacts contained in theenergizing circuit of said motor during operation of said motor, another coil for closing said another pair of contacts connectedin series with said motor during snubbing action of said motor and means controlled by saidiiirst mentioned coil for shunting said first mentioned coil .upon applicationiof current to saidmotor,

whereby said indicating device cannot assume its energized condition unless the contacts controlled by the said traiiic controlling device are closed and'a dynamic current has been flowing ingsaid another coil since the last operation of said motor; 8. In an interlocking system for railroads, the combination with traffic controlling device,'a motor for operating said traffic controlling device, a cross protection relay at times connected in a branch circuit in multiple with saldmotor, an indicatingodevice for indicating-the operated position of said trafiic controlling device controlled by an in dicating circuit including a circuit controller operatedby said traflic controlling device, a pair of contacts in said indicating circuit,a coil for opening said a pair of contacts, said coil being included in the energizing circuit of said motor duringoperation of said motor, another coil for closing said a pair of contacts and connected in series with said motor Cllll'. mg snubblng act on of said motor,'and shuntmg contacts controlled by said first inentioned coil for shunting the same upon the apphcatlon of current to said motor, the resistance of said first mentioned coil being such as to prevent operation of said motor until Sald first mentloned 'coil has operated the shunting "contacts, whereby said motor cannotbe' operated unless'said first mentioned coil hasbe'en'shunted andsaid apair of con; tacts have beenopened, and whereby said in dicating device cannot assume its energized condition unless the circuit controller operat governing said circuit, means automatically interrupting said circuit upon movement of the lever, and means automatically operated by current generated dynamically by said motor after operation of the traflic controlling device for reclosing said circuit.

10. In an electric interlocking system, a motor operated trafiic controlling device, a lever controlling the application of current to said motor, a' three position relay in the tower for indicating the position of said device, a polarized indication circuit for controlling said relay, a circuit controller operated by said device for governing said circuit, and electrically operable circuit controlling means associatedwith said lever for interrupting said indication circuit upon movement of said lever and prior to the application of operating current to the motor, said means acting to reclose said circuit after the motor has completed the movement of said trafiic controlling device.

11. In an electric interlocking system," a-

traific controlling device having an operating motor, a lever, operating circuits for said motor governed by said lever, said motor being included in a closed snubbing circuit after each operation of the traflic controlling device, a cross protection device included in said closed snubbing circuit and responsive to the direction of current flow therein, contacts closed in the eventcurrent of one polarity flows in said snubbing circuit but not closed in the event current flow of the opposite po larity therein, and a separate polarized indication circuit controlled by the position of said traflic controlling device and said contacts. V V

12. In an electric interlocking system, the

combination with a traific controlling device having an operating motor, of a polarized indication circuit governed by the position of said device, a circuit controller included in said circuit, operating and snubbing circuits for the motor, and coils included in said respective circuits for opening and closing said circuit controller. a

13. In an electric interlocking system, a track switch, a reversible motor for moving said switch, operating and snubbing circuits for the motor alternately established during movement of the switch, a separate indication circuit controlled by the position of the WVILLIAM HENRY.

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