US1283069A

US1283069A - Electric interlocking system for railways.

Info

Publication number: US1283069A
Application number: US10680916A
Authority: US
Inventors: Charles S Bushnell
Original assignee: General Railway Signal Co
Current assignee: SPX Corp
Priority date: 1916-06-30
Filing date: 1916-06-30
Publication date: 1918-10-29
Anticipated expiration: 1935-10-29

Description

C. S. BUSHNELL. ELECTRIC INTEHLOCKING SYSTEM FOR RAILWAYS.

APPLICATION HLED JUNE 30. I916- Pzitepted Oct. 29, 1-918.

L l/VVE/VTOR M $6M 5. 4 TTOR/VEV CHI-ES S. BUSHNELL, OF ROCHESTER, NEW YORK, ASSIGNOR T0 GENERAL RAILWAY SIGNAL COMPANY, OF GATES, NEW YORK, A CORPORATION OF NEW YORK.

' ELECTRIC INTERLOCKING SYSTEM FOR RAILWA'YS.

reeaoce.

Specification of Letters Patent Patented Oct. so, rare.

Application filed June 30, 1816. Serial No. 106,809.

- larly to such apparatus commonly termed in the art electric interlocking systems.

In one type of electric interlocking systems, to which this invention more particu-' larly relates, energy mains are used for supplying current for operating, controlling and indicating the operation of the various switches, signals or other functions of the interlocking system, and the movements of each function are controlled by an electrically operated remote control relay or similar circuit controlling device, said remote control relay being in turn governed by the usual lever associated with that function. In this type of electric interlocking system the indication circuits for the lever of each function are governed by a second indication relay which is controlled by the operating mechanism of that function. In systems of this type it has] been heretofore found necessary to so-construct and arrange the parts that the complete cycle of operation and indication must be carried through upon each movement of the lever; or in other words, if the operator has moved his lover from a given position.- it is necessary for the complete cycle of movement of the function and the indication of its new position to occur before the lever can be returned again to said given position; It is desirable, however, for reasons which are well understood by those skilled in the art, that the operator after moving his lever from (a given position should be able to immediately restore that lever to said given position Without carrying out the complete cycle of movement of the function, providing the. function has been completely restored to its former position. 'A lever which is capable of such a movement ma be termed a free lever; and

the primary 0 ject of this invention is a construction and arrangement of parts in the type of interlocking system generally above described whereby the operator is able to restore his lever to either of its extreme positions at any time providing the function controlled by that lever is in the condition cor-- responding to that extreme position, or in other words, a construction and arrangement of parts whereb all of the advantages incident to the use 0 the free lever may be obtained.

Other objects and advantages will appear as the description of the invention progresses, and the novel features of the invention will be particularly pointed out in the appended claims.

In describing the invention in detail reference is had to the accompanying drawing in which is illustrated a preferred physical embodiment of the invention and in which the figure is a diagrammatic View, in the nature of a wiring diagram, showing the construction and arrangement of parts, together with their electrical connections, of an electric interlocking system embodying the invention.

Referring to the accompanying drawings, the letters B and C indicate the energy mains which in practice extend around among the switches, signals and other functions governed by the interlocking machine, said energy mains B and C being connected to a suitable source of current, which is shown as a transformer T. The use of any suitable or well known type of interlocking machine is contemplated accordin to this invention, and in the illustrated em odiment of the invention one of the so-called levers L of such an interlocking machine .is shown. This lever L is supported by suitable guides (not shown) so as to be movable back and forth, and is provided with a suitable handle 5 for facilitating its manual movement. In practice the lever L is used in conjunction with other levers which are interconnected by the well known mechanical interlocking, and in the type of lever'shown, this mechanical interlocking is actuated .by a link 6 carrying a roller at its upper end which is guided in a cam slot 7 in said lever. In the lever L is formed an irregular shaped opening or indication slot 8, the upper edge of which is so shaped as to'leave near each end of said slot a shoulder 9 and a V-shaped projection 10 near the middle of said slot. The lower edge of the slot 8 is so shaped as to leave shoulders 11 and 11 which are located one on each side of the middle point of said slot and a short distance therefrom. The purpose of the shoulders 9, l1 and 11 and the reason for the irregular shape of the indication slot 8 will be explained more fully hereinafter in the description of the operation.

end of a rod 13 which extends downwardly through and is guided by the yoke of the indication magnet l and has secured to its lower end a bar 11 constituting the armature of said indication magnet. The indication latch 12, the rod 13 and the armature 11, due

-to their own weight, aided by any suitable other means if desired, tend to move to the lower position shown in the drawing, in

which position the armature 1%. is spaced away from the pole faces of the indication magnet- I. so that. energization of said indication magnet raises the armature 14, the rod 13 and the indication latch 12.

The lever L governs its corresponding function by controlling certain electric circuits and for this purpose a rod 15 is connected at one end to said lever and at-its other end to a contact carrying bar 16 which is guided in any suitable way (not shown) so as to lnove back and forth with the movements of the lever L. The bar 16 'arries a number of contact blocks 17. 18, 19, 20 and 21, which are insulated from each other and are arranged to cooperate with pairs of contact springs 22 to 31, inclusive, in the different positions of the lever L.

The lever L has four significant positions, namely: first, an innermost position (shown in the drawing), which position is conveniently termed the normal position; second, a position in which the lever is pulled outward (to the left as viewed in the drawing) to its outermost extreme, this position being conveniently termed the reverse position; third, at position near the inner or normal position in which the indication latch 12 is in engagement with theshoulder 11, but in which the rod 6 has notbeen forced down by the cam slot 7 to its lowermost position. this position of the lever being conveniently termed the normal indication position; and fourth, a position near the outer or reverse position in Which the indication latch 12 is in engagement with the reverse shoulder 11 but in which the rod (3 has not been raised to its uppermost position, this latter position of the lever being conveniently termed the reverse indication position.

The pairs of contact springs 22-23 and 30-31 are so arranged that their respective contact blocks 17 and 21 may make electrical contact therewith when the lever L is in either its full reverse position or full normal position, but so that said contact blocks 17 and 21 will not make electrical contact with said pairs of contact springs in any other position of the lever. The pairs of contact springs 24-25 and 2627 are so arranged cording to established convention.

that their

respective contact blocks

18 and 19 may make. electrical contact therewith in the reverse indication position and in the normal indication position of the lever L, but so that. said contact blocks 18 and 15) will not make electrical contact with said contact springs in any other position of the lever. The pairs of contact springs 28 and 29 are arranged to make contact with the corresponding contact block 20 when the lever L is in either its normal positionv or its normal indication position, 0' any point between, and when itis in its reverse position or its re verse indication position or any point between.

For the purpose of controlling the indica tion circuits in the manner more fully explained hereinafter, an electrically operated circuit controlling device is used, and in the particular form of the invention shown this device is illustrated conventionally as a three-position alternating current relay IR of well known construction. conveniently termed the indication relay, which comprises a winding 32 and a winding 33, the winding 33 being connected by

conductors

31, 35, 3G and

conductors

3T, 38 and 39 across the energy mains B and C and being thereby permanently energized. The indication relay IR isprovided with two contact fingers or armatures l0 and 1-1 which are. shown, together with their cooperating contacts, ac-

These armatures l0 and 11 not only cooperate with fixed contacts in each of their extreme positions, but are also so arranged as to maintain a circuit closed at any point between one extreme position and the neutral position, this characteristic of the relay being indicated by the use of the arcuate contact segments 42 and 48.

The parts so far described are located in the tower or cabin, and the other parts at the right. end of the drawing are located at the function to be controlled,.this function in the particular arrangement shown being a switch; and the mechanisnrfor operating this switch comprises a motor designed to be operated by alternating current, having an armature A. an operating field F and a compensating field F. A circuit controlling device, herein termed the pole changer P, is ope 'atively connected to the switch points or to the switch operating mechanism so asto be moved in accordance with the movements of said switch points and said mechanism, and comprises a supporting panel 44 of insulating material to which are secured a number of contact bars or strips designated 45 to 51 inclusive. These contact bars are arranged to make electrical contact.. with corresponding pairs of contact springs 55 to 64, inclusive, in different positions of the panel. 41. The panel issupported and guided so as to reciprocate from right to left as viewed in the drawing and has three signlficant positions, namely: one extreme or normal osition corresponding to that shown 'in the crawing, in which the switch points are in the normal position and are locked, an intermediate ormiddle position, which corresponds to 'the position of the parts of the switch operating mechanism when it has been so operated as to unlock the switch points or has placed the switch points at any point in the movement of said switch points from one position to another; and the other extreme or reverse position opposite to that shown in' the drawing in which the switch points are in the reverse position and are locked. While the pole changer panel-44 may be caused to assume its three different positions described by different mechanical constructions, one simplified construction is shown as comprising a" motion plate 150 guided by suitable guldes 151. This motion plate is connected to a switch point 152 by a link 153, andin the motion plate is formed a cam slot 154 which is suitably shaped to cause movement of a roller 155 connected to the panel 44 by a link 156 so as to cause the desired movement of this panel as described. It should be understood, however, that the construction illustrated and just described is adopted for the sake of simplicity, and that in practies the panel 44 is operatively connected to the operating parts of the switch mechanism, so that its movement is dependent upon a completion of the cycle of operation of this mechanism, all as well understood in the art, The pairs of contact springs 55 to 64 inclusive are of different lengths and are so arranged with reference to the corresponding contact blocks 45 to 54, inclusive, that when the pole changer P is in its normal extreme position, as shownin the drawing, each of the pairs of contact springs 55 to 59, inclusive, is in electrical contact with the corresponding contact bars 45, 47 ,49, 51 and 53. When the pole changer P is shifted to its intermediate position the contact blocks. 45 and 49 are moved out of contact with thepairs of contact springs 55 and 57, while the contact blocks 47, 51 and 53 remain in contact with the pairs of contact springs 56, 58 and 59; and at the same time the contact blocks 46, 50 and 54 are brought into contact with the pairs of contact springs 60,

'62 and 64. lVhen the pole changer P is shifted to its extreme reverse position, that is, when the switch points have been shifted by the switch operating mechanism to the full reverse position and are locked in that position, all of the

contact blocks

46, 48, 50, 52 and 54 are in electrical contact with the pairs of contact springs 60 to 64, inclusive, and the other contact bars 45, 47,51 and 53 are moved out of electrical contact with the pairs of contact springs 55 to 59-, inclusive.

, Also associated with the switch operating mechanism is an electrically operable circuit controlling device which is shown as a three position alternating current relay RC, herein termed the remote control relay, which comprises a winding and a winding 66, the winding 66 being connected by the

conductors

67 and 68 across the energy mains B and C and being thereby permanently ener- &

gized. The remote control relay RC is pro- 9 vided with a number of armatures or contact fingers 69 to 76 inclusive, which are capable of assuming any one of three positions.- A transformer T is also preferably located at the switch for obtaining suitable voltage for the circuits controlling the indication relay IR.

The electrical connections between the different parts hereinbefore described will not be pointed out in detail since the different electrical circuits involving these connec. tions will be traced and their function fully explained in the description of the operation. Operation: In the accompanying drawing the parts associated with the switch and the parts associated with the lever L are shown in the normal position corresponding to the position in which the switch points are in their normal position and are locked in'that position. In the particular embodiment of the invention illustrated the current used for controlling, operating and indicating the operation of the switch is alternating current, and although the direction of flow of current eriodically reverses as is well understood y those skilled in the art, it is convenient to assume that the energy mains B and C have a definite polarity at a given instant, as indicated in the accompanying drawing. With the parts in the normal posit-ion the winding 65 of the remote control relay RC is energized by a circuit which may be traced as follows:

C'z'r'cuit nwmbe-r one.

Commencing at the energy main B, conductors 77 and 78, contact springs 29 and contact block 20, conductors 79 and 80, winding 65, conductors 81 and 82, contact springs 31 and contact block 21, and

conductors

83 and 84, to the other energy main C.

When the parts are in the normal position. shown the winding 32 of the indication relay IR is energized by a circuit which may be traced as follows:

Circuit number two.

Commencing at the terminal marked positive of the secondary of the transformer T conductors 85 and 86, contact springs 55 and contact block 45, conductor 87 armature 69 of the relayRC in its normal position, conductors 88 and 89, winding 32, conductor 90, armature 71 of the relay BC in its normal position, conductor 91, contact springs 57 and contact block 49, and conductors 92-and 93 to the terminal of the secondary of the transformer T- marked negative. .1

' When the operator wishes to cause the switch to assumejts reverse position he pulls the lever L to'the left as viewed in the ac- 'companying drawing to its reverse indicatn position. As the lever L is moved by the operator to the left, the indication latch Y 12 is forced down by the projection 10 into position to strike the shoulder 11 and before the lever can be moved farther it is necessary to lift the indication latch 12 by energizing the indication magnet I. When the contact block21 moves out of contact with the pair of contact springs 31, the circuit number one for energizing the winding circuit, however, as can readily. be seen,

. leaves the connections from the energy mains to the winding 65, so that the circuit may be said to be of opposite polarity to circuit number one, said circuit being traced as follows:

Uircuit number three.

Commencing at the energy main B, conductor 77, contact springs 28 and contact block 20, conductors 94, 95 and 81, winding 65,

conductors

80, 79 and 96, contact springs 26 and contact block 19,

conductors

97, 98 and 99, armature 41 in its neutral position, arcuate strip 43, and conductors 100 and 36 to the other energy main C.

. Thislast traced circuit causes the armatures of the remote control relay RC to assume their reverse position indicated by dotted lines, in a manner and for the reasons well understood by those skilled in the art, and in this position of said armatures the winding 32 of the relay IR is shortcircuited by a low resistance path which may be traced as follows: commencing at one termlnal of the winding 32, conductor 89, armature reversed, conductor 101, cont-act springs 56 and contact block 47, conductor 102, contact springs 58 and contact block 51, conductor 103, armature 72 reversed, and conductors 104 and 90 to the other terminal of the winding 36. This shortcircuiting of the winding 32 of'the indication relay IR affords a special safeguard by preventing any possibility 'of'the armatures of said relay IR being reversed while the armatures 7 of the remote control relay RC are reversed and while the switch operating mechanism is in the normal position.

As soon as the armatures of the remote control relay RC assumetheir reversed position, the switch operating motor is supplied with currentalong a circuit whichmay be traced as follows:

Circuit number four.

The switch operating motor being sup-.

plied with current causes a movement of the switch points to their reversed position, and when the full cycle of operation of the switch operating mechanism is completed and the switch points are fully reversed and locked, the pole changer P is shifted to its reverse position and interrupts the reverse operating circuit number four for the motor and also the path which short circuits the winding 32 of the relay IR, and establishes a circuit of opposite polarity to circuit number two for energizing the winding 32 of said relay to cause its armatures to assume their reversed position, said circuit of reversed polarity being traced as follows:

Circuit number fire. Commencing at the terminal marked positive of the secondary of the transformer T conductors 85 and 117, contact springs 63 and contact block 52, conductors 118 and 103, armature 72 reversed, conductors 104 and 90,

.winding 32, conductor 89, armature 70 reversed, conductors 101 and 119, contact springs 61 and contact block 48, and

conductors

120 and 93 to the terminal of said secondary marked negative.

When the armatures of the indicationrelay assume the reversed osition, the reverse indicationcircuit is esta lished, which may be traced as follows:

Circuit mmnbcr sz'w.

Commencing at the energy main B,

conductors

39, 38 and 121, armature 40 reversed, conductors 122 and 123, contact springs 24 and contact block 18, conductors 124 and 125,

indication magnet I and conductor 126 to the energy main C. i

This last traced circuit energizes the coils of the indication magnet I and raises the indication latch 12 so as to clear-the reverse indication shoulder 11 thereby permitting the lever to be pulled by the operator to its full reverse position. When the lever L is moved to the full reverse position, contact raeaoce block 18 is moved out of contact with the contact springs 24, thereby interrupting the reverse indication circuit number six; and the contact block 19 is moved out of contact with the contact spring 26 so as to interrupt that another circuit for energizing the windished as follows:

ing 65 of the remote control relay RC is esta. 1

v Circuit number seven.

Commencing at the energy main B, conductor 77, contact springs 28 and contact block 20, conductors 94, 95 and 81, winding 65, conductors80 and 127, contact springs 30 and contact block 21 and

conductors

128 and 84 to the energy main C.

The operation ofmoving the switch from its normal position to its reverse position is now completed, the lever L bein in its full reverse position, the armatures o the remote control relay RC being moved to their reverse position indicated by the dotted lines, and the armatures of the indication relay IR being also moved to their reverse position indicated by the dotted lines.

The operation of moving the switch from its reverse position back again to the normal position shown in the drawing involves sub stantially the same sequence of operation, and the circuits set up during this movement of the switch may be easily traced by analogy to the circuits already traced.

As described hereinbefore, the

difierent positions dur-in the complete cycle of operation of the switch machine.

. reason for causing this panel to assume its intermediate or middle position at the beginningof the cycle is to enable the motor to be reversed while the switch points are in mid-stroke. It will be evident that when the panel 44 is in its middle position, the contact blocks 53 and 54 are both in contact with their respective pairs of contact springs 59 and-64, so that a circuit for operating the motor in either direction may be established by reversing the armatures of the remote control relay RC. It will also be noted that the pairs of contact springs 55, 61, 57 andv 63 are shorter than the pairs of springs 60, 56, 62 and. 58. These pairs of contact springs are also arranged with reference to their cooperating contact blocks so that the shorter contact springs will be electrically connected only when the pole changer panel 44 is in its correspondingextreme position, whereas the longer springs will be electri cally connected while the pole changer panel is in its intermediateposition as well as the corresponding extreme position. The cirpole, changer panel 44 is caused to assume three One the normal position. construction, which is slmilar to the conof the switch includes the pair of contact springs 55 and 57 when the pole changer panel 44 is in its normal extreme position and when the secondary of the transformer T is connected in this circuit. Upon movement of the panel 44 to its intermediate position, this circuit is broken at the pairs of contact springs 55 and 57 and at the same time the short circuit, hereinbefore deseribed,is established by the pairs of contact springs 60 and 62. In a similar way, the pairs of contact springs 61 and 63 control the connection of the source of current into the circuit for the winding 32 of the relay IR for the reverse position of the switch, while the pairs of contactsprings 56-and 58 control the short circuit connection for this circuit. The pairs of contact springs 60, 56,

62, and 58,.as shown, are made of such a length and are soarranged with relation to their coiiperating contact blocks that all of these pairs of contact springs will be electrically connected when the pole changer panel 44 is in its intermediate or middle position. By reason of this construction when the switch is in mid-stroke, both of the circuits leading to the winding 32 of the indication relay IR are caused to be short-circuited when one or the other is set up at the armatures of the remote control relay RC. Consequently, while the switch operating mechanism is in mid-stroke, it is assured that the armatures of the indication relay IR will remain in their neutral position.

Interlocking systems of the type shown and described have heretofore generally been constructed so that the contacts controlled by the lever L and which govern the indication circuits are constructed differently from the simple pairs of contact springs 24 and 25 and the contact block 18 shown in the drawing and have been designed so that when one indication circuit is interrupted by placing the lever in the'corresponding extreme position, this indication circuit cannot again be reestablished until the lever has been moved to its other extreme position" and back again. The reason-Why I this construction has been adopted heretofore may be better understood if it is as: sumed that the control of the remote control relay RC in the system illustrated and hereinbefore described is modified so as not to be dependent in any wise upon the operation of the indication relay IR, so that said remote control relay may be reversed at the same time the armatures of the indication relay are in struction used in the systems of this type heretofore devised, when the armatures of the remote control relay are reversed, current is immediately supplied to the switch In such a modified operating mechanism in the same way as explained hereinbefore, and likewise at the same instant the circuit for normally energizing the indication relay IR is broken. Suppose now that with such a modified construction the operator for some reason quickly returns his lever back to the normal indication position before there is time for the armatures of the indication relay to drop; then, under theseconditions, it is readily apparent that if no means were provided for interrupting the normal indication cirsuit at this time, a false indication might be received, because the current has been applied to the switch operating mechanism and may have unlocked the switch points 01 even have caused a partialmovement thereof, while a normal indication has been received and the lever has been moved to its normal position. To obviate this objectionable conditionit was found necessary to use the speciallyconstructed contacts for governing the indication circuit as described above; but the adoption of these specially constructed contacts made such a modification of the system as to make it necessary for the operator to carry out the full cycle of movement of a function each time he moves a lever. There is, however, .a saving of time and other advantages in enablingthe operator to return a lever to its prior position without going through the full cycle of movement of the function, providing suitable safeguards are adopted so that there is no possibility of obtaining a false indication in the manner above described. For example, to illustrate a special condition where the use of a free lever is of great importance, it may happen that there issome obstruction which prevents the complete movement of the switch points to their reverse position; and if the operator, ignorant of this fact, attempts to reverse the switch, he would be unable to get his lever either in the full normal position or in the full reverse position in the systems heretofore devised for the reason that the obstruction prevents the complete movement of the switch points to the reverse position and the obtaining of a reverse indication, and the construction of the system is such that no indication can be obtained in the normal position until the lever has been placed in its reverse position.

' There is no objection, however, in permitting the operator to return his lever back to the normal position providing the function also returns to its normal position; and in the instance just cited it is apparent that such an arrangement is of great importance in preventing great delay; and this desirable result is accomplished in the system constructed according to this invention by reason of the-inter-control of the remote control rela and the indication relay.

From the circuits hereinbefore traced and indication circuit corresponding to the position then occupied by the switch is interrupted, so that there is no possibility of obtaining an improper indication by quickly moving the lever in one direction and then back again.

Among features of the system shown and described which serve to protect thesystem against improper operation by crosses, grounds and the like between the control operating mechanism to beand indication wires extending between the tower and the switch operating mechanism, it is noted that since the motor of the switch operating mechanism is controlled by a polarized device, namely, the remote control relay RC, in order to obtain a change in the position of the armatures of said relay RC and a reversal of the switch op erating mechanism, it is' necessary tohave a special breaking and reverse connection between the control wires 80 and 81 to pro duce a change in the polarity of thecurrent flowing in the winding 65 of the remote control relay; and since breaks and crosses of this type are not at all likely to occur, the system is ,very effectively protected against an improper operation. It 7 may happen that the conductors 89 and 90 which supply current to the winding 32 of the indication relay IR will be broken and so reversely connected that the armatures.

of said relay will be shifted from the position they then occupy to their other position; and it can be seen that when the armatures are so shifted they will be in the position to establish the indication circuit for the position of the lever opposite to the position it then occupies, so that unless some safeguarding means is provided, it might be possible for a false indication to be given if the operator were to shift. his lever while the armatures of the indication relay IR- were so shifted to the position opposite to what they should occupy. The

possibility of so obtaining a false indication is prevented in the system embodying this invention, however, because, if the armatures 0f the indication relay IR are improperly changed from the position which they occupy. the indication magnet I will be energized so as to lock the lever L in the position it then occupies, so that not only is the operator advised by the action 1 0 of the indication magnet I, which under the influence of alternating current ordinarily causes a chattering or rattling noise, but the operator is also unable to move the lever L and crossing of the conductors 89 and 90 as will cause a reversal in polarity of the current supplied to the winding 32 of said relay. As soon as the armature 40 reaches its shifted or dotted line position, a circuit is established for energizing the indication magnet I as follows:

Circuit number eight. 7

Commencing at the energy main B,

conductors

39, 38 and 121, armature {10 reversed, conductor 122, contact springs 23 and contact block 17,

conductors

131, 132 and 125, indication magnet I, and conductor 126 to the energy main C.

It should be noted that when the lever L is in either its extreme normal or reverse position, the remote control relay RC is not controlled by the indication relay IR, whereas when the lever L is in either of its indication positions the armatures of the remote control relay RC cannot be shifted unless the armatures of the indication relay IR have reached the neutral position. The reason for making it necessary for the armatures of the relay IR to be in the neutral position before the circuit number three for reversing the armatures of the relay RC can be established is to prevent the possibility of obtaining a false indication by moving the lever L from its normal position to its reverse indication position and then quickiy back again to its normal indication position, as explained hereinbefore; but when the lever L is in its full reverse'position, it is necessary to make the control of the remote control relay RC independent of the indication relay IR in order that the control of said relay RC by said relay IR will not interfere with the locking of the lever L by establishing the circuit number eight and energizing the indication magnet I in case the armatures of the indication relay IR are improperly shifted due to a breaking and crossmg of the wires 89 and 90. In other words, whileiit is necessary tornake the arrangement of circuits such that when the lever L is in its reverse indication position, the shifting of the armatures of the remote control relay RC is dependent upon the armatures of the indication relay IR being in the neutral position, so that the possibility of obtaining a false indication is prevented; it is necessary, on the other hand, to have the relay RC controlled independently of the relay IR when the lever L is in its full reverse position. To explain more specifically, assume that the relay RC is controlled by the relay IR when the lever L is in the full reverse position 1n the same way as when the lever is in the reverse indication position, that is, that the circuit number three is established when the leverL is in full reverse position rather than circuit number seven, and then assume that the armatures of the relay IR are shifted from the position which they then occupy to the opposite position by the breaking and crossing of the wires 89 and 90 such as to cause a reversal of polarity of the current flowing through, the 'winding 32' of said relay IR. With these assumptions 1t can be seen that, when the armatures of the relay IR are then shifted improperly, re-

membering that it is assumed that the circult number three is established at this time, the winding 65 of the relay RC is delinergized, and consequently its armatures assume the neutral position; but as soon as the armatures of the relay RC move to the neutral position the current of reversed polarity for energizing the winding 32 of the relay IR is interrupted, so that the armatures of said relay IR in turn assume the neutral position; and as soon as the armatures of the relay IR reach their neutral position the circuit number three is again established and energizes the Winding 65 of the relay RC and causes its armatures to assume their previous position and again supply current to the winding 32 of the relay IR, whereupon the same alternate energization and denergization of the relays IR and RC continues in a: sort of see-sawing action which causes the lndication magnet I to be energized intermittently instead of steadily. With the arrangement of controlling circuits shown and described, however, this difficulty is avoided, since, when the lever L is in its full reverse position, the Winding 65 of the relay RC is energized by circuit number seven which is .not affected by the shifting of the armatures of the relay IR, so that when conditions are such asto cause a shifting of the armatures of therelay IR and the establishing of circuit number eight, this circuit will be permanently established and will hold the indication magnet I energized and the lever L locked so long as the cross or the like which caused the shifting of the armatures of the relay IR persists.

' Other features and advantages of the system embodying this invention will be apparent to those skilled in the art without further explanation.

Although I have particularly described the construction of one physical embodiment of my invention, and explained the operation and principle thereof; nevertheless, I desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical embodiments of the idea of means underlying my invention.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an electric interlocking system, in combination: an electrically operable function; an electrically operated circuit controller for governing said function; a lever for governing said circuit controller; indication inechanism for said lever; indication circuits for governing said indication mechanism; a relay for governing said indication circuits; and means for preventing the operation of said circuit controller to operate said function until said relay is in condition to interrupt said indication circuits.

2. In an electric interlocking system, in-

combination: an electrically operable function; a lever for governing said function; indication mechanism for said lever; indication circuits for governing said indication mechansm; means governed by said lever for controlling said function; and means for interrupting both of said indication circuits prior to the operation of said last mentioned means.

3. In an electric interlocking system, in combination: an electrically operable -func tion; a polarized relay for governing said function; a lever for governing said relay; indication mechanism for said lever; indication circuits, one for each position of the function, for controlling said indication mechanism; contacts operated by the lever and included in said indication circuits, and means for automatically interrupting the indication circuit corresponding to the existing position of the function before said polarized relay can be operated to a position corresponding to the other position of the function.

4. In an electric interlocking system, in combination: an electrically operable function; a polarized remote control relay'for governing said function; controlling C11- cuits for said remote control relay; a lever for governing said controlling circuits; indication mechanism for said lever; indication circuits, one for each position of the function, for governing said indication mechanism; an indication relay for governing said indication circuits; and means controlled by said indication relay for interrupting the indication circuit corresponding to the existing position of the function before the controlling circuit for the other position of said function can be established.

5. In an electric interlocking system, in combiration: an electrically operable function; a polarized remote control relay for governing said function; controlling circuits for the remote control relay; a lever for governing said controlling circuits; indication mechanism for the lever; indication circuits, one for each position of the function for governing said indication mechanism; a

polarized indication relay governed in accordance with the electrical condition of the remote control relay and the position of the function for controlling said indication circuits; and means for preventing current being supplied to the remote control relay when the lever is in either indication position until the indication relay is deenergized to interrupt both indication circuits.

a distant point for governing the operation of the function; indication mechanism at. the distant point; a polarized relay at said distant point governed in accordance with the position of the function for controlling said indication mechanism; and means inter-connecting the remote control means and the relay preventing the application of current to change the position of the function until said relay is deenergized.

8. In an electric interlocking system, in

combination: an electrically operable function; a lever for governing the operation'of said function; an indication magnet for the lever adapted when energized to lock the lever in either its normal or reverse position; a polarized indication relay for controlling the indication magnet and having the position of its armatures determined by the position of the function; and means for energizing the indication magnet upon reversalof the armatures of the indication relay while the lever is in its normal or reverse position, whereby an improper operation of the indication magnet locks the lever.

9. In an electric interlocking system, in combination: an electrically operable function; a lever for controlling the operation of the function; an indication magnet associated with the lever and having the position of its armature determined by the position of the function; and circuit connections for short circuiting the indication magnet when the lever is in its normal or reverse positions and the armature of the indication relay is in a corresponding position.

10. In an electric interlocking system, in

combination: an electrically operable func-' tion; apolarized remote control relay for governing the operation of said function; a lever and controlling circuits for governing said remote control relay; indication circuits for the lever; a polarized indication.

- lay are reversed while'the function is at rest.

11. In an electric interlocking system, in combination: an electrically operable function; a lever for controlling the operation of the function; indication clrcuits for the lever; a polarized indication relay for governing-said indication circuits; means governed automatically in accordance with the position of the function for short-circuiting the indication relay when the function is in an intermediate position; and means dependent upon said relay being de'nergized for controlling the application of current to operate the function.

12. In an electric interlocking system, in combination: an electrically operable function; a polarized remote control relay for governing the operation of the function; a lever for controlling the remote control relay; a polarized indication relay associated with said lever; circuit controlling means operated automatically in accordance with the movement'of the function; and circuit connection controlled by the remote control relay and said circuit controlling means for short circuiting the indication relay when the function is in an intermediate position.

13. In an electric interlocking system, in combination: an electrically operable function; a lever for governing the operation of said function; an indication magnet; a

source of current; circuit controlling means governed automatically in accordance with the movement of the function for controlling the connection between said source and the indication magnet; contacts operated by the lever and closed in the indication positions of the lever for also controlling the connection between the source of current and said indication magnet; and circuit connections for short-circuiting the indication magnet when the lever is moved to its other indication position while said circuit con trolling means remains in its existing position.

14:. In an electric interlocking system, in combination: a function; a motor for operating the function comprising an armature and a field;.a source of current; circuit controllers governed automatically in accordance with the movement ofthe function and selectively opened and closed according to the position of the function; both of said circuit controllers being closed when the function is in an intermediate operating circuit for each posltion of the function including the corresponding circuit controller; the source of current and the armature and field of the motor in series, and a remote control relay governed from a distant point for reversing the connections of the field of the motor but not the armature in the respective operating circuits.

CHARLES s, BUSHNELL.

position; an'