US1114430A - Induction automatic stop and cab-signal system. - Google Patents

Description

c. L. BOPP. l l INDUCTION AUTOMATIC STOYPAND CAB SIGNAL SYSTEM.

APPLICATION FILED JULY .26, 1912.

f Patented Dot. 2U, 1914.

4 SHEETS-SHEET 1.

ifi

witness@ l C. L.' BOPP.

INDUCTION AUTOMATIC STOP AND'OAB SIGNAL SYSTEM.

APPLICATION FILED JULY z'e. 1912. 1,1 14,430. f Patented 0.312,0,.1914

4 SHEETS-SHEET 2.

C. L. BOPP. INDUCTION AUTOMATIC STOP AND GAB SIGNAL SYSTEM.

APPLICATION FILED JULY Z6, 1912. 1,-1 14,430. v Patented oct. 2o, 1914n 4 SHEETS-SHEET 3.

(22725027 l.. 5gg/0'.

attorneys o. L.l BOPP. INDUCTION AUTOMATIC STOP 'AND CAB SIGNAL SYSTEM.

APPLwATIoNI'ILED' JULY 26.1912. y Patented 0013. 20, 1914 4A SHEETS-SHEET 4.

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@Zi/M100 L. 9o/0,0.

CLINTON L. BOPP, OF WATERLOO, IOWA.

INDUCTION AUTOMATIC STOP AND CAB-SIGNAL SYSTEM.

Specification of Letters Patent.

Patented Oct. 20, 1914:.

Application led July 26, 1912. Serial No. 711,746.

To all whom it may concern.'

le it known that I, CLINTON L. BOPP, a citizen of the United States, residing at Waterltilo, in the county of Blackhawk and State of Iowa, have invented certain new and useful Improvements in Induction Automatic Stop and Cab-Signal Systems; and I do hereby declare .the following to .be a full, clear, and exact description of the invention, such as will enable othersskilled inthe art to which it appertains to make and use the same.

This invention relates to improvements in railway signaling systems where the principle of magnetic induction is employed to set into operation mechanism which will indicate the condition of the line.

VAn object of the invention is to provide a simplied system to break circuits which require no insulation between adjacent blocks' and where no,` current flows except when a train is in the system.

' Another object of the invention is to provide-a inagnetically actuated needle for reducing the resistance of a cab signal circuit so that signal circuits may be closed as the needle isy actuated.-

With these and various other objects "which will appear as the description proceeds, the invention resides in the combination'andarrangement of parts shown and vdescribed more/fully in the following speciication and claims.

Inthe drawings: Figure 1 is a diagrammatic viewof 'a section of railway tracking .showing the saine divided into four blocks with wiring. Fig. 2 is a similar diagrammatic view showing the track with one train in the system. Fig. 3 is a similar diagram- ,matic View showing two trains traveling in the saine direction. Fig. 4 is a similar diagrammatic view showing two trams 1n adjacent blocks approaching each other. Fig. 5 is a view, part in elevation and part shown diagrammatically of the locomotive equipment when'the same is set to indicate safety. Fig. (3 is a view similar to Fig. 5 showing the locomotive equipment set when the line is in Fig. 7 is a section through a casin in which is mounted an improved time rake setter. Fig. 8 is a fragnlontani vicw slimving the locationlof the magnetic needle relative to the wheel of the lmoniotive. Fig. S) shows a modified .View o the needle. Fig. l() showsfdetall view of one of the fuses used in the invention.

This invention depends upon the well known electrical phenomenon that a inagnetic needle suspended in a magnetic field set up by current flowing through a wire will be deflected at an angle to the wire. Another fact Which is made use of in the present invention is that high potential current will jump the shortest air gap thrust in its path. The general arrangement of the invention isA to provide a needle deflected by current flowing in a conductor, a source of high potential current having an air gap in its circuit which is ,to be regulated by the needle as it swings and certain local circuits designed to be broken as the current flows in the high potential circuit. l

. In order that the invention may be better understood, the conditions of the track circuits will be traced first.

By referring to Fig. 1, where normal conditions of the track system are shown, it will be seen that rails 1 and 2 are connected respectively to positive and negative poles of a plurality of line batteries, 3, 4, 5, and 6.

The rail l is connected to the positive poles of the batteries 3, 4, 5, and 6 by means of wires 7, 8, 9 and 10 respectively, and the negative poles are connected to rail 2 by means of wires l1, 12, 13 and 14 respectively. It will be seen from the matter illustrated in Fig. 1 that no current normally flows between the two tracks, or if any current does flow due to leakage it,will be so infinitesimal as not to affect the operation of the system. The points where wires 7, is', 9 and l0 connect with rail 1 define blocks A, B, C and D. f

Referring to Fig. 2, it will be seen that train T\has been shown as having entered block C,\1nd that a magnetic needle is carried overglail 1 in front of the foremost right wheel, said needle being shown more clearly in Figs. 8 and 9. When the train '.l is in the position shown all of the batteries in the line will feed through the axles ol said train, the batteries 3 and l together with all those to the left of 3 feeding through rail 1, and under the needle, while batteries 5 and 6 together with all batteries to the right of battery 6 feed through the axles of train T withoutv passing under the needle. Under these conditions therefor, the batteries in the blocks ahead of the block -pointe .train T has moved to b occupied by the train furnish' the current which deflects the needle carried by the flow through the axles of the train T without affecting the needle carried by the train T. Inasmuch as each of the trains T and T eat many axles, the resistance of the 1 has a path ronirail 1 t0 rail 2 will be so exceedlngly 1liir' that it may be considered neglig le and that the said rails are short-circuitedat the point where the wheels contact. With respect to Fig. 3 therefore, it will be seen that the parts of the track extending between the two trains are short l eircuited and that no difference of potential exists between the rails 1 and 2 in this part of the track by virtue of eitherA the set of batteries to the leftor to the right of the section. The only current which can fiow through the rails of the track between the two trains is that furnished by battery 4.

Tracing the circuit from battery 4, it will be seen that at the point where wire 8 is connected to rail 1, two paths are open to the current, one of which leads forward to the train T and across to the left hand side of train T, while the other path leads back through rail l to train T across to the other rail 2, and forward to the left hand Side of train T. As shown in Fig. 3 it might be estimated that the first of these paths is approximately one-third the length of the second path, it being remembered that the resistance of the train is negligible. Since in a divided circuit current in the various branches will vary inversely as; the resistance of those respective circuits, itlgis obvious that the current, through the first of the above circuits will be three times the current in the second circuit traced. It might be considered that the current in wire 8 was divided so `that three-fourths took the shorter path, whereas one-fourth took the longer path.v

Hence, when two trains are traveling in the samev direction andl are in adjacent blocks, the train ahead will have its needle deflected, while the rear train will be traveling over the track which is carrying current insufficient to operate the needle carriedby said rear train.

Referring to Fig. 4, it will be seen that as pointed out in the above paragraph, the battery 3 and all batteries to the left thereof will feed through train T in block B, but inasmuch as train T i's moving to the right the current from battery 3 will not effect the needle carried by train T. Similarly, batteries 5 and 6 together with all the batteries to the right of battery 6 will flow through train '1" without affecting its needle. As before the current from battery 4 will divide, the lesser current passing through the longer circuit. Inasmuch as the trains are approaching each other, their needles will be located over the divided circuit in which the weaker current is flowing, hence neither of the needles will be' deflected, giving the signal to each'engineer. Should train T be just in front of the point where wire 7 connects with rail 1, and train T' be just in front ojf the point where wire 8 connects with rail 1, then, as in the case just described, battery 3 and the batteries to the left thereof will not affect the needle carried by train T. Also, battery 5 and all batteries to the right thereof will not affect the needle carried by train T. There will be two paths open for the flow of current from battery 4, viz., battery 4, wire 8, over the upper rail of block B, through the train T to wire 12, back to battery, train T being close to .the point of contact between wire 12 and rail 2. The other circuit is; battery 4', wire 8, through train T', 'over the lower rail of block B,.up wire 12, and back t-o battery 4. But these circuits are of substantially equal length, therefore the currents flowing through Said circuits are substantially equal; The needles carried by the trains'are so designed as not to be' "ilefiected far enough when half current flows to keep conditions normal and the needles will therefore tend to aline with the rails, as hereinafter described. From these various circuits, it will be seen that .when trains are in adjacent blocks and traveling in the same direction. the rear train will be. given a signal through its needle, the condition for giving a signal being that the needle shall not be deflected by a current in the rail and further that if two trainsl be in adjacent blocks and approaching each other, neither needle will be deflected and both `trains will be given a signal.

The magnetic needle associated with the mechanism shown diagrammatically in Figs. 5 and 6 islocated just in front of the first right hand wheel of the locomotive looking in the direction of travel. From this it will be seen that when two trains approach each other as shown in Fig. 4, part of the rail which is directly under the needle containing ease shown in Fig. 8 is not carrying the normal currentv necessary to deflect the needle fully, the result of which is to allow needle contained in the case to line up with the rail, which will be described more fully hereinafter.

Referring now to Fig. 5 it will be seen lao Aio

that a section ofthe rail is indicated at 16,l switch 17 being shown in circuit with battery 18 for the purpose of making-and Abreaking cii'cu-it'through rail 16. This diagrammatic means ofl showing the making and reakingof vcircuit throughlG is 'shown in Fig. 5721s a simple means of sending current through the rail section 16 which condition Iwill necessarily be assumed in describing the operation of the cab circuits. Shown pivotally mounted at` 19 is a magnetic needle A20 of .greater length than the width of the tread of rail 16, the needle 20 adapted t0 such as for instance a coil, mounted to -swing above the rail, the coil having a discharge point' which is adapted to swing in close noximity to strip 21. In either event, the discharge point upon the swinging nieinber is to be provided with platinum vor, other non-oxidizing metal, which is .not

readily eaten away'by thel passage of a high :potential spark.

If so desired, an astatic zcouple, such as is illusti'atcdin Fig. 9, may used as a moving member, Vthe-fadfvaiitage .of using'said couplebeing that it.

isyvey much more sensitive than afsingle :needle,v and therefore would yield` to a much weaker current hm'ing in the'rail.v `Although these various modifications have any needle capable of being deflected by been referred to, it is to be understood that such-a curi-ent as wiil railgmay'be used. l .Byrefcrring to'Fig. 5 it willbe seen vthat two mechanisms aside from the ina` etic needle generally indicated at N fares Own, the `first mechanism beingr the source of cunrcnt supply shown at l, and the secondfa fuse distributing mechanism F. The mechanism l comprises a generator 22 having normally flow in the brushes 23 and 24 mounted upon a shaft25.

l 'Ih-ere isalso mounted upon shaft 25 a coniii'iutatorf-v26 having insulated sections 4V27 and 28, these insulated sections being"` designed vto breakrcircuit through brushes 29 and-3() as the generator revolves upon-shaft 25. lf the moving car upon which the mechanism isfloeated be a strain loi-.ometlve a turbo generator set can be used to drive gene-'l rator 22, while if the mechanism be installed upoufian electric. locon'iotivel suitable trailsniecl'ianismjust described furnishes direct current. induction coil or other high potenliaf apparatus 321s designedto furnish' alternating currentof high pressure, primary '33 of said induction coil being excited from the generator through connnutator by the following circuit: Brush 24, wire 34, primary Y33, wire 35 brush 30, interrupter 26, brush 29, wireA36, brush 23, back to the commutator of the generator. It will be secu that insomuch as' interrupter 26 is inserted in this circuit, the current is vcontinuously interrupted so long as motor 22 revolves, the result of which is to furnish the primary of the induction coil with a' iiuctuating current, whereby an alternating current is produced in the secondary 33 of Said coil.

At F is-shown a usedelivering mechanism provided with a statitnary member 37 and a sliding member 38. tationary/m m ber 3T is composed of a housing 39 in w ich t are piled a series of fuses40, said/f being of ordinary construction' and/having metallic ends separated by 'a strip -of-insulation, said ends bein connected bymeans of fusible metal carried by the insulation. (See Fig. 10.) Brackets 41 and 42 are rigid with member 37 but insulated thoroughly therefrom, the object of said-insulationbelv ing .to prevent any jumping of currentl frome the secondary ofthe induction coil' tof,v the housing 39. vBracket 41-,carrie`s a regulablef idischarge member 43,:whilevva similar regu-V` y i labledischarge member is .fcarriedubly f bracket 42. Afspringpcontac't -45 is Acarried on the side of the housing); AThe sliding. l

member 38 comprises insulating 'bei seh-av-Jl l g ing an upraised portion 63nd 'h'ayiifi'g tvvvoA contact plates 47. and,48seeured tothe lin'si'il lating base. A third contacty plate 'T49 Vex-k tending the full length of the movable member 38 is. provided central-Iofsa'id; movable.-

,member and serves 'as a common vconductor foncurient passing through plates 4f( and 48. Flexible springs @carried by but insu'- ilated from stationary member 37 aregprml vided with depending lugs which: Li'n'tol suitable recesses formed intheimetiallic'ends of the fuses foi removing 'the saine, whichy after. y. l'For the purpose tof,v clearnesg, the' snpportsjor the-springs .to '.the vfr';ight' ,of

understood that y,thigag-supports upon each side -of the fuse holder Aare identical.-'Pa'rtM4 146;, is raised above the contactfplates'i? and v483,

just 'enough to `retain one of tlie .fuses"40 upon thc Contact plates as the member v-38 slideslmder stationary member 37. .Pivoted as at 52 is a lever 53 having a bifurcated end 54 which is' `designed to engagea pinfgu' carried by the movable'4 member 38,. v'v'hli'c construction admits of the-moizingo'f m'ni swinging of the needle 20 will be traced. It will be assumed that the lcurrent is owing 1n rail 1G, that needle 20 is deflected as indicated, and that the fuse delivering mechanism F is in the position shown in Fig. 5. With current flow-ing in rail 16 it isA desired to show that safety will be indicatedby the that magnet 60 is energized and. that as a.

result armature 65,secured rigidly to lever 53 is attracted to the said electro-magnet. There is also a second circuit contemporaneous with the one just traced which is as follows: Brush 24, wire 56, electro-magnet 57, wire 58,' wire 66, electro-magnet 67, wire 68, contact plate 47, the pile of fuses 40, contact plate 49, wire 63, wire 64, back to generator 22 by way of brush 23. Current flowing in this circuit will energize magnet 67 and it will be seen that the air gap between wthe armature 69 secured rigidly to the lever 53 is greater than that between electro-magnets 60 and armature 65, the natural result of which is that lever 53 will remain in the position shown so long as electro-magnet 60 is energized. The lever 53 carries a spring p contact 70 which, as shown in Fig. 5, makes contact with contacting screw 71, which causes the following circuit: Brush 24, wire 56, wire 72, wire 73, contact brush 45, wire 74, lever 53, contact sprin 70, contacting screw 71, wire 75, contact 76, armature 77, contact 78, wire 79, electro-magnet 80, wire 81, wire 82, to junction 83, Where current divides, part of it going through wire 84, electro-magnet 85, wire 86, wire 87, back to the generator by meansl of brush 23, and part of it going from the junction 83 to wire 88, white light 89, wire 90, wire 87, back to brush 23`of generator 22. Thus, s'o long as contact spring 70 engages contact screw 71, a current` will' be maintained through electro-magnet 85fiwhich controls the'brakes of the train and clear light 89.

To explain further the operation of the mechanism it will be assumed that current has failed in the rail 16 under such conditions as are indicated in Figs. 3 and 4, the necessary result of which will be the lining up of ythe magnet 20 with rail 16. When this is done it will be apparent that the air gap between needle 20 and the strip 2l'\vill bey Aconsiderably enlarged. The air gap regulator is placed considerably closer to the fuse 91 than airgap regulator 44 is to fuse 62. It will be seen that when air gap 92 is placed in series with variable airgap 93 at the needle, high potential current will pass through wire 94, wire 95, manually operated switch 96, contact 97, wire 98, strip 21, and will jump gap 93, when needle 20 is as shown in Fig. '5, will pass through the needle 20 to wire 99, down air gap regulator 43, will jump gap 92, will pass to strip 49, wire 63, back to secondary. The sum of the lengths of the air gaps 92 and 93#with needle 20, as. is shown in Fig. 5, are designed to be less than air gap 101 which is between air gap regulator 44 and fuse 62. As needle 20 swings, however, the sum of the air gaps 92 and 93 will exceed the vlength of air gap 101 so that the resistance of the air gap in the circuit .containing air gap 101 will be less than the resistance of the air gap of the circuit just traced. Under these conditions the following high potential circuit will be .set up: Current will start from secondary 33 of the induction coil, pass through Wire 94, wire 102, spark gap regulator 44, air gap 101, plate 49, wire 63, back to the secondary of the induction coil. As shown in Fig. 5 the fusible art of the fuse 62 is directly in the path ofp air gap 101 so that as current flows in the circuit just traced the fuse will be melted and the circuit containing electromagnet 60 will be broken. With electromagnet 60 denergized and magnet 67 still energized the sliding member 58 will move to the new position indicated in Fig. 6. lnsomuch as magnet 67 will attract armature 69 formed rigid with lever` 53 the conditions just traced-are desired to be accompanied by a signal showing that the line is in condition of danger, such indication being contemporaneous with condition of no current in rail 16. As lever 53 swings to the new position shown in Fig. 6, contact spring 70 wi'll. contact with contact screw 100, when the following circuits will be completed: Brush 24, wire 56, wire 72, Wire 73, contact spring 45, wi're 74, lever 53, spring Y70, contact screw 100, wire 103, Wire 104, red lamp 105, wire 106, wire 90, wire-87, brush 23, back to generator 22. Current flowingin this circuit will light red light 105, the burn-` ing of ight 105 being caused by the making of con acts 70 vand 100 which necessarily broke contacts 70 and 71'. Insomuch as. 'contacts 70 and 71 were in series with electromagnet 85`and clear light 89,V it will be apparent that the latter mentioned devices will be inoperative.

In order, to complete the cycle of opera tion it will be necessary to assume that current is again flowing in rail 16, the natural result of tvhich will be to deflect needle 20 until th/e same is in the position .shown in Fig. 5. The mechanism at F under this consideration will be as shown in Fig. 6, where-` as thb needle will be shown as in Fig. 5. It will be seen that as shown in Fig. 6 the spark gap 92 has interposed therein the fusible dition. Just as soon as the needle 20 becomes close, enoughv to strip: 21 'to reduce the sum of the airk gaps 92 and 93 to a length less than air gapV 101 the current will of cenare lrake a shorter path and flow through the two air ga s 92 and 93. The flowing of current throng air ap 92 and the circuits which have already een traced will result in the fusing of the fuse 91, which fuse is in series with the electro-magnet ,67, so that said electro-magnet is denergized. It will be noted, however, that pile of fuses 40 is under this present consideration in such a position as to make the circuit containing magnet complete, so that said magnet will be energized, the natural result of which is to attract: armature (i5 and throw the mechanism in thel position shown in Fig. 5. Se tar the description has shown a complete cycle of the signaling apparatus in normal conditions when no bad fuses have been delivered, and when the generator has been generating continuously, and when there is a sutiiciency of fuses in housing 39.

If at any time one of the fuses bridging plates 47 and`48 had been blown or a defective fuse had been delivered by the mechanism F, then the path of the circuit leading to the ,magnets and 67 would have been opened. It will be seen that if the path of magnets (30 and 67 is opened ity necessarily follows that magnet 57 will also be opened the result of which will be the dropping ot arn'iature 77, which will close contacts 107 and 108. `When this contact is made the following circuit is made: Current will start from hrnsh'fl, wire 56, wire 105).,contact 107, armature 77, Contact 108, wire`Ll0, wire 103, wire 104,1' d light 105. wire 10(3,wire $10, wire 87, brush 2.- back to generator 22. Thus, it will be seen that in the event ol the mechanism F delivering a defective fuse the same wili be indi ated 4to the engineer by the lighting of -d light=105. Should the dynamo fail to Lop'erate, no cin-rent will he fed to electroanagnet 85, the result of which will be the deinergizalion of said magnet with the conseuluent setting of the brakes to be described hereinafter. l

.t weight '111 is mounted in housing 37 upon the "pile otV fuses 40 for the purpose of hoiding said fuses as each successive fuse is tai-:cn vfrom the bottom of the ile. Of course a spring could be used for this same purpose, but in either event it would be desirable to have projections 112 carried by the means for pressing the fuses into place, the pari-ose of which would he to contactwith' spring when the fuse supply was low to break contact between spring 45 and wire '1,71 and to malte contact between spring 45 and wire 113. lVhen this last; mentioned contact is made the following circuit will be completerlaf/brush 24, wire 56, wire '72, wire 72" spring 415,y yyvire 113, wire 104, the red light V105. wil-e106, wire 90, wire 87, brush 23, back to the generator 22. Current flowing in this circuit which is closed when the fuse supply has been exhausted or about to be exhausted will light red light 105 which is an indication that part of the mechanism is in need of attention. As shown in either Fig. 5 or (5 a spring ejector .'10 provided with a depending point 51 is carried by bracket 41 so that as the swinging member 38 slides under stationary member 37 the point 51 will engage the fuses. To the right of Fig. 5 where the fuse ejecting mechanism is duplicated it will he seen that depending lug or point 51 is in such a position that when member 38 swings thc fuse (S2 will be carried to the position indicated in Fig. 6. Upon the next oscillation of the fuse delivering mechanism a dead fuse will be carried out by the points of lugs 51 and will force olf of the contact strips 48, and 49 the first fuse 62, thereby providing for the automatic ejection of the dead fuses. It is to be borne in mind of course that the Contact between the bifurcation 54 and the pin 55 is to be insulated so that no current can pass from lever 53 to the fuse delivering mechanism'F.

From the circuits traced it will be seen that magnets 80 and 85 are thrown across generator 22 in series so that if either of said magnets become denergized it will be accompanied by the simultaneous denergi- Zation of the' other. A spring actuated armature 114, suitably pivoted to the frame of they ocomotive and provided with a notch 115 is designed to be held in an upward position by electro-magnet S0 so long as the ,said magnet is energized.` A spring actuated lever 116, suitably pivoted to the locomotive. is designed to be released by the patch 115.115 electro-magnet S0 attracts arm-v ature 114. .\s the lever 116 is released it will be drawn by a spring 117 against a manually operable button 1.18, by means of which said lever can be made to close contact with contact. point 119i Insoinuch as he brake setting means, which is operated y electro-magnet S5. is time controlled, it will be possible for the engineer to prevent -the setting of the brakes after electro-magnet S0 has been denergized by simply pushing 'manually operable button 118, which will -close the following circuit: brush 24, wire 56, wirc 72. wire 120, lever 116, contact point 119, wire 121, wire 82, wire 84, electro- 'magnet 85. wire S6. wire 87. brush 23, back to generator 22. From the circuit it will be seen that current flowing as indicated will lenergize electro-magnet 85, a result ot' which valve 124. The pawl-lever 122 pivoted to `the frame at 125 has at one end a movable weight 126 for adjusting the balance of the lever so that said end carrying the weight will descend as electro-magnet 85 is denergized. The other end of the lever 122 which is provided with a catch 127, engages a ratchet wheel 128rigidl secured to a cani 129 mounted upon s aft 130. Formed integral with cam 129 is a weight 131 the purpose of which is to rotate the cam 129 as pawl-lever 122 is raised from ratchet wheel 128, by descent of weight 126. A suitable opening 132, formed between the weight 131 and cam 129 shows a graduated scale 133 whereby the rate of rotation can be roughly estimated by the engineer. Part of the cam 129 is formed' with teeth as at 134, for the purpose of engaging a inion 135, said pinion carrying with 1t a an 136, whereby the descent of weight 131 is restrained from being too rapid. Pi"- oted to the air brake 124 as at 136 is a. screw carrying arm 137 the outer end of which is pron'ded with a roller 138, for engaging cam 129. As the cam 129 rotates under the influence of weight 131` the roller 138 will rest upon the surface 139 of cam 129 until portion 140 arrives under the roller 138, which condition will result in the dropping of arm 137 and the consequent drop ing of iston 140 mounted in the air bra e caslng 124. The valve 141 which is loosely engaged by pistonA 140 will, as a result of the dropping of piston 140. open a passage bctween air pipe 142 and exhaust pipe 143. In this way it will be seen that the air brakes may be set by the denergization of electro-magnet 85 after an desired interval of time has elapsed, sai time being dependent upon the Asize of fan 136. Pivoted about shaft 130 is an engineers lever 144 having mounted therein a rod 145 provided with a teeth engaging point 146 and sliding within said lever 144. A spring 147 carried within lever 144 is designed to hold point 146-normall 128, but sai point may be forced into en- A gagement with said Wheel by means of ed across said air gap, a regulable air V1n multiple with the variable air gap, a use away from the ratchet Wheel he wishes, the fan 139 not interfering with the return movement of cam 149.

lVhat I claim is: 1. In a railway signal system, a variable air gap, a source of high potential connectlocated in the regulable air gap, an electric device, a source of current, a closed circuit including the fuse electric device and source of current, and means for varying the length of the variable air gap, the length of the variable air ap adapted at times to exceed thelength o? the regulable air gap.

2. In a railway signal system, a source of high potential an electrode connected to one si c of said source,'a magneticneedle connected to the other side of said source and adapted to have one end thereof swing in proximity to said electrode, an air gap conncctcd in multiple across said electrode and magnetic needle, a closed circuit, a portion of said circuit being fusible and located within the second mentioned air gap, electro magnetic means for deflecting the needle, the distance between the/needle and electrode adapted ut times to exceed the' length of the second mentioned air gap,

3. A variable air gap, a regulable sur. gap, a source of high potential, means ,for connecting said gaps in multiple across the source of high potential, a closed signaling circuit, a portion of said circuit being fusible and located within the second air gap and means for varying*y the length of the variable air gap, the variable air gapfadapted at times to exceed the length of the second air gap.

4. In an electric signaling system, an electric current conductor having magnetic properties, a magnetic needle, an electrode, a source of high potential connecting thc electrode and needle, an ailxgap connectedV in multiple across the electrode and magnetic needle, a closed circuit a portion of said circuit being fusible and located within the air ga i, said magnetic needle being no1-mall de ected by current assinlg in the con uctor to have one end adljacent-the electrode, said needle adapted to alinewitli the conductor whenno current is flowing inY in presence o two witnesses.

CLINTON L. BQPP. lVitnesses F. W. EKLUNY H.y Il. S0110.

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