US1824162A - Interlocking system for railroads - Google Patents

Description

Patented Sept. 22 1931 UNITED STATES JOHN C. LINDNER,

PATENT OFFICE INTERLOCKING SYSTEM FOR RAILROADS I Application filed August 12, 1929. Serial No. 38%,l72.

This invention relates to power interlocking systems for railroads, and more particularly pertains'to features of cross protection and means of indicating in the interlocking tower-the position of switch points in the well known dynamic indicating type of electric interlocking system. v

In an interlocking system,- it is necessary that the si nals, governing the tr'afiic over a track switch, shall give indications in accordance with the position and locked condition of that particular switch. This is often'accompli'shed by the provision of a signal selecting or SS relay, indicating the position of the switch points, for selecting-or controlling the signals governing the route over that particular switch; i I

In onetype of dynamic indication system, it is proposed to provide control circuits, for such a SS relay, which are governed in accordancewith the position and locked condition of the switch points; the correspondence of the control lever with the switch machine which it controls; and the integrity of movement of the switch machine by unauthorized currents.

One object of the present invention is to provide improved control circuits of this .30 type fora SS relay used in the well known dynamic indication typeof interlocking system, which circuits are protected from shorts or crosses occurring between the control circuits of one SS relay and the control circuits of another such SS relay.

A further object is to provide control circuits for such a SS'relay which are jointly .controlled by two groups of contacts, one group of which is operated bythe switch points and the other groups of which are operated by the switch machine, so asto apply potential of opposite polarities to the control wires of the SS relaywhen the switch machine is in extreme positions and locked and the track switch operated thereby is also in extreme positions and locked,but to cutoff such energy and shunt the SS relay control wires when both the track switch and switch machine are not in corresponding extreme positions, due to a disconnected or the cross protection circuits p'rotectlng the I ",ent invention.

broken throw -bar or some other such failure.

V The present invention provides thecontrol of such a SS relay in a manner having the advantages of separate control wires, while usingthe common return of the switch ma.- chine control as one control wire of the SS relay. Thus, an economical control for a SS relay'is provided by the present invention. e c

Various other objects purposes and charand in part obviousfromthe accompanying drawings, as a description of the invention progresses.

In describing the invention, reference will be made to the accompanying drawings, in which like reference characters refer to like devices, and infwhich 4 r Fig. 1 is a diagrammatic View of an interlocking system including the present inventlon; v

Fig". 2 is a diagrammatic view showing the control of two SS relays as included within the present invention; V

F 1g.'3 shows a side view of a point detector "shunt contact as included withinth'e present invention; A

F 1g. 4- showsa side view of the point detector contacts as included within the pres- Vith reference to the drawings, Fig. 1 shows in a diagrammatic manner a track switch TS as operated by a switch machine SM. This switch machine SM is preferably of the type described in the patent to W. K.,

cs nocnns'rna, nnw Yon'K, ASSIGNOR TO GENERAL RAILWAY srenar ccivrrANY, on aocnnsmrn, NE'W YORK u u I l acteristic features will be in part pointed out,

Howe, No. 1,466,903, dated September 4,1923,

with certain modifications as hereinafter stated.

Theswitch machine SM hasthe usual motor, with; an armature A and a field wind- "known as the pole changer coil contacts,

shown within a dotted rectangle FCC; and a third group of contacts, known as the point detector contacts, shown within a dotted rectangle PD. The pole changer contacts PG have associated therewith two series coils.

'ing F, and includes three groups of contacts,

. Henry and F.

S and S and two shunt coils SH and SH which operate to hold movable contact members 5 and 6 in one extreme position, or to operate them to an opposite extreme position to effect the reversibility to the switch machine SM in midstroke. These movable contact blocks 5 and 6 make contact between certain pairs of fixed contacts when in opposite extreme positions and are operated to these opposite positions when the switch machine SM has completed an operation and is locked. The pole changer coil contacts PCC have, movable contact blocks 7 8, 9 and 10 which are operated to contacting extreme positions at the end of each operation of the switch machine SM when it is locked and assume intermediate positions during the operation. The purpose of the shunt coils SH and SH is to afford reversibility of the switch machine from a midstroke position, in that these coils electromagnetically operate the contact blocks 5 and 6 to a position to operate the motor A-F in the proper direction; The series coils S and S although they are not used to operate the contact blocks 5 and 6 will hold these contact blocks 5 and 6 into their last operated position, this because only one of these coils S or S are included in the normal circuit or the reverse circuit, respectively. It may be pointed out here, that should the shunt coils SH or SH burn out, the companion series coil S or S will serve to hold the contact blocks 5 and 6 in their proper position to which they were mechanically operated during the completion of the last operating stroke of the switch machine.

These movable contact blocks 5, 6, 7, 8, 9

and 10 are operated by the action ofthe throw barof the switch machine in a manner as set forth in the patent to "W. K. Howe, W. S. M. Hall No. 1,307,200, dated June 17,1919. WVith such an arrangement the track switch 's operated and locked by the throw bar of the switch machine, thus eliminating the use of lock rods.-. However, the usual point detector bars are used to operate the point detector contacts.

The point detector contacts PD include movable contact blocks 11, 12 and 13 which make contact between certain pairs of fixed contacts in extreme positions only The point detector contacts PD also include shunt con tacts 14 and 15, which are biased to make contact with their respective fixedcontact members 16 and 17 except when actuated. The movable contact blocks 11 12 and 13 are moved to extreme normal positions and the shunt contact 15 is actuated to a non-contacting posit-ion, when the track switch TS is in a normal position and locked; also the .movable contact blocks 11, 12 and 12 assume intermediate central positions and the shunt contacts 14 and 15 assume contacting positions when the switch machine SM is in oper ation for controlling the track switch TS to either of its extreme positions; also the contact blocks 11, 12 and 13 are moved to opposite extreme or reverse positions and the shunt contact 14 is actuated to a non-contacting position when the track switch TS is in a reverse position and locked. Such an example of contacts controlled by the position of switch points is shown in a patent to G. S. Bushnell No. 1,517,236 dated November 25, 1924.

Associated with the point detector contacts PD, is a local transformer 20 having primary and secondary windings 21 and 22, respectively. The primary w1nding21 is energized from a suitable alternating current source over two line wires extending from the tower. The primary and secondary circuits of the transformer 20 preferably include resistances 23 and 24, respectively, for compensating for the various lengths and varying resistances of the control wires which may be used for the control of a SS relay in the interlocking tower.

Associated with the track switch TS is the usual detector track circuit, having a track relay T supplied from a suitable track battery designated 25. i

In the interlocking tower there is provided bers in the normal and reverse positions in the usual manner.

Associated with the lever L in the interlocking tower is an indication responsivedevice IR, which includes a normal and a reverse operating winding N I and RI, respectively for controlling a dead-beat armature 33 to either a normal or a reverse dotted line position, in which positions certain indication clrcuits are completed as hereinafter described. A track repeating relay TB is provided in the tower for indicating the position of the track relay T.

A cross protection relay GR is provided, having two windings 34 and 35 which cooperate in a manner as completely described in a patent to N. H. Reichard No. 1,713,494, dated May 14, 1929, for actuating a spring .tensioned armature 36, which, when actuated,

releases a biased contacting member 37 for breaking certain normally made circuits and closing certain other circuits after the actuation of the armature 36 until the contact member 37 has been manually reset.

The SS relay includes a local winding 38 and a line phase winding 39 which operate to control a contact 40 to either a normal or a reverse position according to the relative instantaneous polarities in the local phase winding 38 and the line phase winding 39. The local phase winding 38 is continuously energized from a local transformer 1, having its primary winding energized from the same alternating current potential source as the local transformer at the switch; The line phase winding 39 is energizedfrom the local transformer 20 .over certain control circuits as hereinafter pointed out.- V

A suitable battery ET is provided for the direct current operating potential for the i eh machine SM, having a fuse F included within the circuit for overload protection. his to be understood that in place of the battery BT various other types of sources of electrical energy maybe used for supplying direct or alternating currents. p

l-rsseciated with the cross protection relay GR, is an indicator light 42, which indicates when illuminated that the cross protection relay CR has'been energized in a' manner to actuate the armature 36 and releasethe normally mace contact member 37. Also, an indicator light l3 is provided to indicate when illuminated the deenergized position of the contact .40 of the relay SS. Also, another indicator light llindicates the deenergized position of the track repeater relay TR. These various indicator lamps are supplied from suitable alternating or direct current sources, which in this case have been designated alternating current sourceshaving the opposite terminals indicated by the reference characters BX and CK.

'lnterconnecting the lever in the interlocking tower with the switch machine SM are the normal and reverse control wires N and B, respectively, which in conjunction with a common return wire C serve to operate the switch machine SM, Also, a control wire WP is provided in conjunction with the common return wire C for accomplishing the cnergization of the line phase winding 39 of the relay SS. 9

Operation The circuits and devices shown in Fig. 1 are in their normal condition.

With the switch machine SM in the normal position and the track switch TS in its normal and locked condition, as shown, a circuit for energizingthe line phase winding 39 of the relay SS may be traced as follows :from

the right hand terminal of the secondary winding 22 of transformer 20, through res-1stan ce 2 1, wire 70. contacts 71-12,w1res 73 and 74., shunt contact 14, fixed contact 16, wire 75,

common wire C, wires 76 and 77, contacts 78-:l2, wire 80, movable contact member 33, wire 81, line phase winding'39 of the relay SS, wire lVP, contacts 84t8. wire 86, contacts 87-13 wire 89, to the left hand ter-' minal of secondarywinding 22. i

As the'local winding 88 of the relay'SS 1s continuously energized from the secondary of transformer 41, the contact assumes an energized right hand extreme position. lVith the contact 40 of the relay SS in the right hand energized position, the indicator lamp l3 is not illuminated, while various circuits governing the signals associated with track switch TS are completed as indicated on the drawings. It is not considered necessary that these signal circuits should be shown in their specific form, as they'may be any standard type of circuit andwould vary considerably according to the conditions to be met in practice.

Assuming that the operator in the tower desires to reverse the track switch TS in order to route the east bound trafiic over the said switch, he will press the lever latch 28 and move the lever L to a left hand extreme position, which may be accomplished in as much as the detector track section, associated with the switch TS, is not occupied, This means that the track relay T and the track repeater relay TR are energized, so that when the latch 28 is pressed, the contact 27 is closed and the force droplock magnet 26 is energized.

lVith the lever L in a left hand extreme position, the reverse operating circuit forthe switch machine SM is completed, causing energy to flow from the battery BT through a circuit traced as follows z from the positive terminal of battery BT, through fuse Rwires 90 and 91, contacts 9230, wire 94, reverse operating wire R, wires 95 and 96, series pole changer coil S wires 97 and 98, contacts 996, wire 101, armature A, wires 102 and 103, fixed contact 104, movable contact block 5, fixed contact 105, wire 106, field winding F, through thecommon wire C, wire 107, winding 35 of crossprotection relay CR,

wires 108 and 109, contact member 37, wire 110 to the negative terminal of battery The current flowing through the operating circuit passes through the series coil S so that the movable contact blocks 5 and 6 are held in their normal position, while the switch machine SM is unlocked and operating in a reverse direction. Also, this holding effect of the movable contact blocks 5. and 6 is further maintained by potential which is across the shunt coil SI-P, due to its being in multiple with the armature A and field winding F of the motor through a circuit traced as follows :-from the reverse operating wire B, through wires 95 and 111, contacts 112-7, wire 11%, coil SH wire 115, to the common wire C. j-These two pole changer coils S and SH furnish a check upon each other, so that should the shunt coil SH become open the series coil S would be sufficient to prevent vibration or othercauses from moving the movable contact blocks 5 "and 6 from the normal position so long as relay theoperating current of the switch machine SM is flowing.

With the movable contact member 32 thus operated to a reverse position by the lever L, the energizing circuit for the line phase winding 39 of the SS relay, as heretofore traced, is opened, so that the contact 40 im mediately assumes a deenergized position upon the initial movement of the lever L. Thiscondition energizes the indicator lamp 43 withthecontact 40 in a deenergized position as is obvious from the drawings, thus indicating to the operator that the indication responsive device 11% is out of correspondence with the lever L.

After the first initial revolutions of the armature A, the switch machine SM is-unlocked so that the movable contact blocks 7, 8, 9 and 10 are moved to an intermediate or central position; and in this position the energizing circuit forthe line phase winding 39 of the relay SS is further opened. Also, with the movable contact blocks 7 and 9 in a central position, the circuits for the pole changer coils S and SPF are still maintained withadditional circuits closed for the pole changer coils S and S11 so that the switch machine SM can be reversed should the lever L be returned-to its normal position. This is made possible because the application of positive potential to the normal operating wire N would energize the pole changing coils S and 'SH so that the movable contact blocks 5 and 6 would be operated magnetically to'an opposite extreme or reverse position, which positions are normally assumed at the end of the reverse operation of the switch machine SM. 7

Further protection is provided for assuring that the line phase whirling 39 of the SS is deenergized by the provision of the point detector contacts PD. YVit-h the switch machine SM and track switch TS unlocked, the movable contact blocks 11, 12 and 13 are moved to intermediate or non-contacting positions, which removes the alternating potential from the SS relay control wire WP. Also, the shunt contacts 14 and 15 are caused to assume contacting positions during the operation of the switch machine. These shunt contacts complete a circuit from the operating wire WP of the SS relay to the common wire C through wire 116, shunt contact 15, fixed contact 17 wires 117 and 74, shunt contact 14, fixed contact 16, 1d wire 7 5, for shunting any foreign currents which might be applied.

Assuming that the lever L is maintained in a reverse operating position. and that the switch machine SM continues its operation to move the track switch TS to a reverse and locked position, the momentum of the armature A generates a dynamic current which is transmitted over the normal operating wire N as soon as the swltch machine SM is 1n 2.

locked condition and the movable contact blocks 5 and 6 are in reverse positions. This dynamic current energizes the reverse indication coil RI of the indication responsive device IR so that the movable contact member 33 is operated to a reverse dotted line position.

Also, with the track switch TS in a reverse position the movable contact blocks 11, 12 and 13 are operated from the intermediate position to the reverse position and the shunt contact 14 is actuated to a non-contacting position. With the point detector contacts PD in this reversecontacting position, alternating current energy is supplied through reverse contacts of the indication responsive device IR and reverse contacts of the control lever L for energizing the line phase winding 39 with opposite instantaneous polarity relative to the polarity applied through the normal energizing circuit, so that the contact 40 is energized to a reverse left hand dotted line position.

The reverse dynamic indication current flows through a circuit traced as follows from the upper terminal of the armature A, through wire 102, contacts 120 6, wires 122 and 123, coil S wires 124 and 125, normal operating wire N, wire 126, contacts 128-31, wire 129 winding RI of the indication responsive device IR, wires 130 and 131, winding 34 of cross protection relay CB, wire 108, winding 35 of cross protection relay CR, wire 107, common wire C, field winding F,

wire 10G, fixed contact 105, movable contact-- block 5,fiXGCl contact 132, wires 133 and 101 to the lower terminal of the armature A.

The reverse energizing circuit for the line phase winding 39 of the relay SS is traced as follows :from the right hand terminal of the secondary winding 22, through re sistance 24, wires 70 and 134, contacts 135-13, wire 137, fixed contact 17, shunt contact 15, wires 116 and WP, line phase winding 39 of relay SS, wire 81, movable contact member 33 in a reverse dotted line position, wire 138, contacts 140-32, wire 76, common wire C, wire 141, contacts 143-10, wire 144, contacts 14512, wires 147 and 89, to the left hand terminalof the secondary winding 22 of transformer 20.

WVith the contact 40 of the'relay SS in a left hand energized position, the indicator lamp 43 is deenergized, so that the operator is made aware of the fact that the track switch TS'has completed its operation to a reverse position. As the energizing circuit for the line phase winding 39 of the relay SS includes both contacts of the point detector PD and contacts operated by the switch machine SM included in pole changing coil contacts PCO, it is assured that the track switch TS and the switch machine SM are in correspondence and locked conditions. In other words, should the switch machine SM for any reason fail to become locked up or disconnected from the track switch TS the movable contactblocks 7, 8, 9, and 10 would not be in corresponding positions with the contact blocks 11, 12 and 13 and the energizing circuitfor the SS relay would not be completed.

A crossbetween the normaland reverse operating wires N and R would cause current to flow through the windings a4 and of the cross protection relay GR in armanner to energize the armature 36 which would release the contacting member 37 to cause it to assume its dotted line position. With the contact member 37 in its dotted line position, a circuit is completed as obvious from the draw ings forenergizing the indicator lamp 42, giving an indication to the operatonthat the cross protection relay CR has been operated due to some unauthorized current applied to the switch machine SM. 1

It is noted that should the detector track section be occupied when the operator desires to operate the lever L, that the circuit for energizing the indicator lamp 44, with the relay TR deenergized, is completed indieating to the operator thatsuch is the case,

so that he does not endeavor to force the lever L or try to ascertain other causes-for the deenergization of the force drop lock 26. \Vith reference to Fig. 2, the indication circuits for two switch machines are shown with parts of the various devices directly associatedtherewith, with like parts having the same reference characters as in Fig. 1 but having distinctive exponents to point out the devices associated with each individual switch machine.

In the tower, an indication relay SS is shown having a line phase winding 39 controlled through a contact 33 of an indication responsive device 111*, and contacts controlled by a lever L Also, associated therewith is a cross protection relay CR? Similarly, a relay SS is provided having its line phase winding 39 controlled through similar apparatus with like reference charact'ers having exponent b; The respective local windings 38 and 38 are continuously energized by the transformer 41. y

The respective line phase windings ofthe relay SS and SS are controlled over their respective control wires W'P and WP in conjunction with the common wire of the respective switch machines associated with each indication relay and are designated as wires C? and (3 At the switch" machines, or track switches, alternating current is supplied to the control wires VP and WP of the SS relays from suitable local transformers 20 and 2O through their associated point detector contacts PD? nd PD respectively. The

point detector contacts of the respective switch machines are shown as including 'movable contact blocks 150 and 151, also 150* and and 151 which make contact between pairs of fixed contacts when in normal or reverse extreme positions. These movable contact blocks assume extreme positions according to the extreme positions of the associated track switch and switch machines and the locked condition thereof, and assume central or intermediate' positions during the operation of the switch machine and track switch as heretofore described. The point detector con= tact-s in this case have been shown in a simple manner, by which contacts the relative in? stantaneous polarities applied to the control wires ofthe respective SS relays may be reversed. The shunt contacts as shown in Fig. l are omitted in Fig. 2 to simplify the explanation, and to make plain the conditions which make necessar Y the use of such con tacts. a

Let us assume that a cross occurs between the control wire WP and WP represented bythe dotted line extending from a point C to a point C *VVith the point detector contacts ofboth switch machines in positionsas shown, the relative instantaneous polarities are such that the secondary windingsof the transformers 20 and 20 are in multiple with the cross orshunt across the control wires. This results in the false energization of the relay SS? by the transformer 20 during the reverse operation of the switch machine associated with the point detector contacts PD, if it were not forthe indication circuit arrangement as included within the present invention. In other words, the relay SS would not indicate the operation and unlocked condition of its associated track switch and switch machine. This circuit bywhich alternating current from transformer 20 mightpass through relay SS 'is traced as follows :.from the right hand terminal of the secondary of transformer 20", through resistance 24*, wire 152,

contacts '15 3151", wire C wire 154, wind.- ing 35" of cross protection relay GR", wires 155 and 156, contact member 37*, wire157, through the negative bus common to all switch machine and signal functions, wire 158, contact member 37, wires 159 and 160, winding 35 of cross protection relay CR, wires 161 and 162, contacts 78 32, wire 16?), contact member 33 of indication responsive device 11%, wire 164;, line phase winding 39*, of relay SS wire WP to the point C through the cross to the point. C wire P, contacts 165-150", wires 166 and 167, to the left'hand terminal of the secondary of the transformer 20*.

It is noted, that this circuit passes through the coils or windings 35 and 35 of the respective cross protection relays. As these coils are designed for direct'current operation, their alternating current impedance is relatively high and provides that, although this circuitjust traced would allow direct current to pass,'alternating current of an SS can not flow in the circuit. Thus, the results, obtainedwith thiscircuit according tothe present invention, allow the use of the common wires of eachswitch machine for chines and the negative bus common to all the switch machine ;and signal functions. In other words, the indication circuits of all of the switch machines are electrically connected witheach other and to the same battery ET for direct current flow, but are isolated to crosses between these circuits insofar as fiow ofalternatingindication current is concerned, this because alternating current is blocked by the relatively high impedance of the coils 25 and 25 Although the above pointed out isolation of indication circuits is present, the present invention proposes to still further check the int'egrity of the indication circuits by the provision of shunt contacts as shown in Fig. 1. The occasion might arise that a cross or ground would occur between the common wire (hand the common wire C in which casethe isolation of the indication circuits by thehigh impedance of the cross protection relays would be ineffective.

Letus assume, that a cross from the point C to the point C is still present and a second cross from a point C to apoint C is present, in which case, without the shunt contacts as shown in Fig. 1, there would be a circuit for energizing the relay SS from the transformer 20 'while the. switch machine associated withthe point detector contacts PD was in operation. .In other words, the relay SS Wouldnot indicate the operation and unlocked condition of its associated track switch and switch'machine. This circuit is traced as follow :from the right hand side of the secondary of transformer 20 through re sistance: 242 wire 152, contacts 153.151 through common wire C to the point C, through the cross to common wire C at the point C through wire 162, contacts 78 -32 wire 168, movable contact 33 wire 164, winding .39, wire WP, through the cross from point C to point C wire WVP", contacts 165-150?, wires 166 and 167, to the left hand terminal of the secondary to transformer 20 However, according to the present invention, with the circuit as shown-in Fig. 1, such an ;occasion of falsely energizing the relay. SS

could'not occur due to the shuntcontacts 14 and 15. Assuming in this case that such contacts 14 and 15 (not shown) are acting so that during the time that the movable contacts'150 and 151 are in intermediate posi- :tions, the shunt contacts 1 1* and 15 are acting .to shunt the wires WVP and C, the line hase winding 39? ofrelay SS- would then e shunted so that the undesirable circuit heretofore traced could not falsely energize said line phase winding. I g

It is of course to be understood that these circuits and conditions as pointed out'may be conversely true, that is, if it were not for the present invention the same possibility couldarise that the transformer 20 would falsely energize the line phase winding 39 of the relay SS. 7

From the above explanation, it is readily apparent that the shunt contacts of the point detector contacts PD are highly important and should be of such construction that the contact made between the contacting members shall be of as low a resistance as practicable v v With reference to Fig. 3,-the shunt contact 14 and fixed contact 16 .(see Fig. 1) has been shown in detail as operable by a point detector mechanism suchas referred to in the above mentioned patent to C. S. Bushnell No. 1,517,236. 7 I

This point detector 'mechanism'provides an insulated contact block 200 mounted upon a cradle C which ispivotally supported upon a yoke Y. The yoke Y is pivotally attached to a frame 201 of the point detector and biased to'a lower position so that itcauses rollers 202 and 203 to ride upon the surface of detector bars D which have certain depressions or slots into which the rollers 202 and 203 are allowed to enter, in a manner to cause the cradle C'to assume the normal position, as shown, when the track switch associated therewith is in a normal position; to assume a central or vertical position when the asso ciated track switch is not in an extreme position; and to assume a left hand extreme position when the track switch associated there with is in a reverse position. It is of course understood that the detector bars D are controlled by the position of the associated track switch. The cradle C is also acted upon by a lock plunger LP which causes the cradle C to assume a central or vertical position whenever the switch machine, with which it is associated, is unlocked. A complete and detailed description of such a point detector mechanism is given in above referred to pat- 61113.

The, contact block 200 actuates the shunt contact 14 to a non-contacting position, as shown, by engagement with a contact reinforcement 20% The contact reinforcement 204 and a contact spring 205 are riveted to a contact support member 7 206 which in turn is secured by a lock nut 207 to a stud bolt 208. The stud bolt 208 is riveted to the contact limit 209 which is fixedly attached to an insulated block 210 by suitable means shown as screws 211. The contact spring 205 has attached thereto a contacting metal strip 212 of low electrical resistance which engagesanother similarcontacting metal strip 213. This contacting metal strip 213 is supported by an arm 214 which is attached to a terminal member 215 both of which are suitably fastened to an insulating contact member 216. Attached to the terminal member 215 is a stud bolt 217 similar to the stud bolt 208, both of which are suitably supplied with terminal nuts.

fWhen the contact block 200 moves to the left (see Fig. 3), the shunt contact 14 is immediately released and assumes its biased position, due to the contact support member 206 being biased against the contact limit 209. As this position is assumed, the contacting metal strip 212slidable engages the contacting metal strip 213, so that a very good electrical connection is made. In other words, such a shunt contact 14- with its fixed contact 16 is particularly adaptable to the indication system of the present invention, due to the biased construction, and the contact wipe obtained with such construction.

lVith reference to Fig. 4, a fragmentary view of Fig. 3 is shown as including in detail an. example of the other detector point contacts, such as movable contact 12 with its associated fixed contacts 71 and 145 (see Fig. 1) The movable contact member 12 includes a contact supporting member 220 which is attached to the contact block 200 by screws 221. At each extremity of the contact member 220 are mounted contacting metal strips 222 which engage similar strips 223 on their respective fixed contact members 71 and 145. Also, it is noted that the contact member 220 has two arms on each side, upon each of which are mounted the contact strips 222 so that contact is made, when a movable contact 12 is in either extreme position, betweena pair of fixed contacts 71 as diagrammatically shown in Fig. 1.

As the fixed contact members 71 and 145 are similar, a description of thecontact 145 only will be given. The contact metal strip 223 is attached to a contact spring 224 which is limited in its biased position by a limiting member 225, both of which are fixedly attached to a terminal member 226 in a suitable manner. Upon the terminal member 226 a stud 227 is mounted which is provided with suitable terminal nuts.

The movable contact member 12' is shown in a contacting position with the fixed contact 71 (see Fig. i It can be easily seen by comparing the position of the fixed contact member 71 with the position or" the fixed contact member 1&5, that the contact metal strips 222 slidably-engage the contacting metal strip 228, thus furnishing good contact wipe.

Thus, according to the present invention, battery type of indication system isprovided for interlocking systems in an economical manner, by the provision of circuits, in

which the common return wire of the regular switch machine controls may be used as a part of the indication circuits. This is made possible by the present invention, in the provision of means for isolating the indication circuits of each individual trafiic controlling function. The isolation or segregating of the indication circuits is accomplished by the arrangement of circuits and the provision of suitable apparatus contained therein.

Also, the arrangement of circuits and combination of contacting means provides against broken connections between the switch machine and track switch which it con trols. The present invention further includes indicating lamps to give the operator in the interlocking tower such information as will enable him to operate the system in an efficient manner. A further advantage is gained by the assurance that the switch machine will reverse or remain in a particular position due to its reversing contacts being held in their proper position by a suitable holding coil arrangement to insure that such will be the case so long as the switch machine is in operation.

Having described one rather specific embodiment of the indication and control circuits of an interlocking system of the present invention and specific devices included therein, it is desired to be understood that the specific arrangements and forms of devices shown may be modified or altered to a considerable extent in adapting them for various conditions under actual operating conditions, however, all such modifications and adaptathe present invention as defined by the appended claims.

Having described my invention, I now claim tions are to be included within the scope of 1. In an interlocking system, a distant'i05 track switch, a switch machine for operating said track switch, a controllever in the tower governing the operation of said switch ma-. chine over a plurality of control wires including a common return wire, and means including said common return wire, and a separate indication line wire, for indicating in the tower the position and locked condition o'tsaid track switch.

2. In an interlocking system, a distant track switch, a switch machine for operating said track switch, a control lever in the tower, a plurality of control wires connectingsaid switch machine and said control lever includ ing a common return wlre, an electro-respom" dication responsive device energized by in-' :0

dication current generated dynamically by said switch machine after each operation thereof and closing normal and reverse con-- tacts respectively, a relay in the tower having normal and reverse energizing circuits including, said normal and reverse contacts of said control lever, said normal and reverse contacts of said indication responsive device, an indication control wire, and a common return wire of said switch machine.

l. In an interlocking system for railroads, a control lever, a distant switch machine having normal and reverse operatingrwires and a common return wire, a dead-beat armature controlled by dynamic indication current received over said normal and reverse operating wires alternately, a threeposition relay, and means operable to control said three-position relay in accordance with the position of said distant track switch and said switch machine including, contacts operably controlled by said dead-beat armature, contacts operably controlled by said control lever, and said common return wire.

5. In an interlocking system for railroads, a control lever, a distanttrack switch opertively controlling a distant track switch, an electro-res ionsive means in the tower having normal and reverse control circuits and operable to indicate the position of said track switch, means operably controlling said electro-rcsponsive means including, contacts operably controlled by said control lever, and contacts operably controlled by said track switch for reversing the relative polarity applied to said normal and reverse control cir-' cnits, and for disconnecting energy from said control circuits and shunting said control circuits when said track switch is not in certain extreme positions.

6. In an interlocking system for railroads, a control lever, a distant track switch operated by a switch machine, a three-position relay indicating the conditions of said track switch and having normal and reverse energizing circuits, an indication responsive device operably controlled to either of two positions by dynamic current generated by said switch machine with said position in accordance therewith, and circuit controlling means operably controlling the circuits of said three-position relay including, contacts operably controlled by said control lever, con? tacts operably controlled by said indication responsive device, contacts operably controlled by said track switch, and contacts operably controlled by said switch machine, whereby said three-position relay is de-energized, when said track switch and said switch machine are out of correspondence.

7. In an interlocking system for r ilroads, a control lever, a distant track switch operated by a switch machine, a threeposition relay, and circuit controlling means for said relay including, normal contacts operably closed with saidtrack switch and said switch machine in corresponding extreme positions and locked, contacts operably closed when either said switch machines or said track switch are not in extreme positions, and reverse contacts operably closed with said switch machine in corresponding extreme positions and locked.

8. In an interlocking system as shown and described, an electro-responsive means indicating the position of a track switch and having normal and reverse energizing circuits, and contact means operably controlling said energizing circuits including, contacts operably controlled for closing said normal and reverse circuits when said track switch is in corresponding extreme positions and locked, and shuntcontacts assun'iing biased contacting positions when said track switch is not in extreme positions or is unlocked.

9. In an interlocking system, a control lever, a switch machine operating a track switch, a detector track section associated with said track switch, electro-responsive means indicating the position of said track switch, indicating means in the tower for indicating when said track switch or said switch machine or both are not in extreme positions which is controlled upon an unauthorized application of energy to said switch machine.

10. In an interlocking system for railroads, a track switch, a switch machine for operating said switch, a control lever, two control wires and a common return wire connecting said lever and said switch machine, a cross protectionrelay having ditlerential windings for preventing operation of said switch machine by foreign current, an electro-respondsive means operable to different positions to indicate the position of the switch points of said switch and having normal and reverse energizing circuits, each respectively including one of said control wires and said common return wire, and each established only if said lever and said switch machine assume corresponding positions.

11. In an interlocking system for rail roads, a track switch, a switch machine for opcrating said switch having two control wires and a common return wire, a control lever, electrically controlled locking means for looking said lever, a three position relay in the tower having normal and reverse energizing circuits each including respectively one of said control wires and said common return wire and contacts closed only when said lever and switch assumed corresponding positions.

12. In an interlocking system for rail roads, a control lever, electrically operated locking means for locking said lever, a distant switch machine having normal and reverse operating wires, a dead beat armature controlled by dynamic indication current received over said normal and reverse operat- 1ng wires alternately, a three-position relay,

and means operable to control said three-position relay in accordance with said distant switch machine including said normal and reverse operating wires alternately used, and also including contacts operably controlled by said dead heat armature.

13. In an interlocking system for railroads, the combination with a distant track switch, of a switch machine for controlling said track switch; a lever; electrically operated locking means for locking said lever, a normal wire, a reverse wire and a common wire connecting said lever and switch machine; a normal circuit for operating said switch machine including said normal wire and said common wire; a reverse circuit for operating said switch machine including said reverse wire and said common wir indicating means at said lever controlled over two distinctive circuits each circuit including a contact of said lever, a contact operated in accordance with the switch points of said track switch and a contact closed only in response to dynamic current generated by said switch machine after said lever and switch machine assume corresponding positions.

14. In an interlocking system for railroads, an electrically operated switch machine, a control lever having normal and reverse contacts, electrically operated locking means for locking said lever, a relay in the tower having normal and reverse energizing circuits including said lever contacts, and means responsive to indication current generated dynamically by said switch machine after operation thereof for controlling said energizing circuit for said relay.

15. In an interlocking system for railroads, an electrically operated switch machine, a control lever having normal and reverse contacts, electrically operated locking means for locking said lever, a relay in the tower having normal and reverse energizing circuits, an indication responsive device energized by indication current generated dynamically by said switch machine after each operation thereof for closing'normal and reverse contac s respectively, included in the energizing circuits for said relay, and means operated by said lever for opening and closing the energizing circuits for said relay.

16. In an interlocking system for railroads, an electrically operated switch machine, a control lever having normal and reverse contacts, electrically operated locking means for locking said lever, a three position relay in the tower having normal and reverse energizing circuits, and means operated by dynamic indication current produced by said switch machine for alternately closing said circuits.

17. In an interlocking system for railroads, a control lever, electrically operated locking means for locking said lever, a distant switch machine having normal and reverse operating wires, a contact means controlled by dynamic indication current received over said normal and reverse operating wires alternately, a three position relay, and means operable to control said three-position relay in accordance with said distant switch including, said contact means.

' 18. In an interlocking system for railroads, a control lever, an electric lock for locking said lever, a distant track switch controlled by a switch machine, two operating wires connecting said control lever with said distant switch machine, an electroresponsive means indicating the position of said track switch, and means operably controlling said electroresponsive means including said two operating wires alternately used, contacts operated bysaid control lever, and contacts operably controlled by dynamic current received from said distant switch machine.

In testimony whereof I aflix my signature. JOHN C. LINDNER.

inn

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