Патент USA US2135497код для вставки
NOV. 8, 1938. Q_ s. HELD 2,135,497 TRACK CIRCUIT FOR RAILWAY SIGNALING SYSTEMS Filed April 28, 1934 3 Sheets-Sheet l r «(ÚM» „0, FIG. 1. K INVEN ATTORNEY Nov. 8, 1938. Q_ s HELD 2,135,497 'TRACK CIRCUIT FOR RAILWAY SIGNALING SYSTEMS Filed April 28, 1934 3 Sheets-Sheet 2"l 572 B1 4a 4a 47 44 4/5 nas BY 2X4/ 44 ‘m ATTORNEY NOV., 8, 1938. y o, sA HELD 2,135,497 TRACK CIRCUIT FOR RAILWAY SIGNALIING SYSTEMS File@ April 28, 1934 _ _? 5 Sheeìs-Sheet 3 k; 125i _ 68 FIGÄ. 6.9 72 76 AP AC ATTORNEY i Patented Nov. 8, y1938 2,135,497 .UNITED STATES PATENT OFFICE TRACK CIRCUIT Foa-RAILWAY SIGNALING sYs TEMs ’ - Oscars. Field, Rochester, Ñ, Y., assigner to General Railway Signal Company, Rochester ' N. Y. v Application' April 2s, uns,l serial No. '122,934 3o clama (ol. zkt-_41) This invention relates in general to railway signaling track circuits, and more particularly to means for maintaining a constant energiza tion of a track relay associated with such a track throughout the time in which a train is occupy ing the associated track section. , Other objects, purposes and characteristic fea tures of the invention will be obvious as the de circuit regardless of changes in leakage cur scription thereof progresses, during which ref rent between the track rails. This application erences will be made to the accompanying draw is a continuation in part of my prior applica ings, which diagrammatically show the inven tion Ser. No. 703,775 .mod December 23, 1933,- tion ina manner to make it easily understood, now abandoned in favor ot lthis application. rather’than with the view of showing the par A normally energilod track circuit includes ticular ,construction preferably employed in prac 10 a relay energized when the track section is un tice, and in which:--` ~ ~ occupied by current flowing >through the track Fig. 1 shows in a diagrammatic and conven rails in series, and it is necessary to adjustthis tional> manner a preferred form of the present normal energizing current in the track relay to invention as applied to a conventional track a comparatively low value in order to permit a circuit. _ l 15 train occupying the track section to divert suili Fig. 2 is an enlarged sectional view of a por cient current through the wheels and axles tion of the device shown in Fig. 1.. shunting the track rails to reduce this energiz Fig. 3 shows a modified form of the present ing current in the track relay to a degree so as invention and also as applied in another man ~ ' to release its armature. The ballast used be 4 ner to a track circuit. 20 tween the rails of such a track circuit permits a certain amount of leakage current which af fects the track circuit in the same. manner as a train shunt, but to a lesser f‘degree. . This leak „ agecurrent however is notA cfa constant. vvalue Fig. 4 shows _in~.a diagrammatic manner an other modified form o1’ the present invention and also applied in still another manner to a track circuit. , Referring to Fig. 1 of the drawings, a section 25 but varies in accordance with the -amount of ' of railway track rails l is shown divided from the adjacent track by insulated joints 6 to form a the track circuit current must at times be regu I conventioxial insulatedI track section. A vtrack lated to compensate for natural changes inbal relay TR. of the type usually employed to con last condition' in order to maintain a current trol’block signals (such as signal S) is `iihown 30 value in the track relay which permits reliable connected across the left hand end of this track operation. " section to be normally energized from a suitable In'view ci the above and other considerations, source. of energy, such as a storage battery B pro it is proposed in accordance with the present in vided at the right hand‘end of this track section. moisture `present in the ballast, and consequently vention to provide means automatically oper able to' maintain a constant current in a track‘ relay regardless of changes in values of leakage current through the ballast from one rail to the other, but to permit a change in current in the track .relay which is effected by the entrance of a train into the associated track section. In other words, it is proposed to provide a means which automatically distinguishes between the changes in current resulting from diiferent 45 causes in a manner to maintain a predetermined current in a track relay regardless of various changes in ballast leakage current, but to allow -55 l A means for automatically varying the amount of resistance included in series with the battery B is shown in Fig. 1 as an electro-magnetic actu 5 ating means which may be of substantially the same construction as shown and described in Patent No. 1,835,150 granted to O. S. Field, 40 ' ` yThis electro-magnetic operating means is December 8,1931. shown -in perspective in Fig. 1 as comprising two pole pieces l and 9 constructed of suitable mag netic material and shaped as shown to provide two vertical pole surfaces.y The lower ends of these pole> pieces I and 9 are suitably ñxed to oppositeends of a permanent bar magnet Ill to the current in the track relay to change in re form a magnetic ileld structurein which the two sponse to the application or removal of a train vertical pole surfacesl of the pole piece 8 arey of shunt upon the track section. It is further pro ' one polarity and the two verticalpole‘faces of so posed to supplement this means for distinguish the pole piece 9 are of the opposite polarity. It ing between different current changes by a lock is of course obvious that. a constantly energized ing means operable to prevent a change in the electro-magnet may be used in place of the per condition of such a current regulating means marient magnet I0 shown. 55 2 8,185,407 An amature coacting with this held structure is provided by a cylindrical core II of magnetic end of the glass tube 22, and these ends may be provided with suitable flexible leads for connect material which is rotatably mounted between the ing to an external circuit, while the other or left two pole pieces l and 9 by suitable bearings not hand ends of the resistance wire 24 are Joined to shown. Two sectors I2 and Il of magnetic ma l form a closed circuit. or preferably the winding terial are attached to opposite ends of the body on each strip 2t may be of a single continuous re portion of core II by clamping nuts I4, and are sistance wire. A thin strip of insulating material 2l is provided to separate the windings of the two oppositely positioned on the core II so that vari ous portions of one sector registers with a ver tical surface of one pole piece according to the degree of rotation of the core II, while at the same time a corresponding portion of the other sector registers with the opposite vertical surface of the other pole piece. A winding I5 is placed around the core II and may be supported by an insulating shell I4 which is provided with extending lugs I1 on each end entering notches Il in each of the pole pieces l and 9. This supporting means holds the winding 20 I5 out of physical contact with the core II in strips 22. A small globule of mercury 24, or other suitable 10 current conducting liquid, is placed within the glass tube 22. which globule 24 is of a sumcient sise to electrically interconnect at one place only the windings on the two triangular strips 2l. The mercury globule 2l will obviously flow to the low est point within the glass tube 22, which point will always be directly beneath the center of the _ core II, and consequently at various positions of the sector I2, the mercury globule 2l will move within the glass tube 22 to electrically connect or order to permit free rotation of the core I I there in. A means for biasing the amature to a defi shunt out various left-hand portions of the re sistance wire 24. In other words, in Fig. l, as the nite position is necessary in the present applica tion of this electro-magnetic operating means, energization of winding Il is increased to actuate the sector I2 in a counter-clockwise direction. 25 and such a means has for convenience been shown as a counter-weight Il attached to the the mercury globule 2l is shifted to a point nearer the left-hand end of the glass tube 22 thereby right hand side of the sector I2. It is contem plated that a spiral spring may be used advan tageously in biasing this amature arrangement 30 in the place of the counter-weight Il. The winding Ii is connected directly across the right hand end of the track rails i as is obvious shunting the resistance wire 24 of the two strips 22 at a point farther from the extending ends to in Fig. l, and is energized in accordance with the interrail potential at that point. This winding 35 I5 is arranged so that the flux produced by ener~ gization thereof is of a polarity forming a pole at the sector I2 which is opposite to the magnetic pole produced in the pole piece 9 by the perma nent magnet I0, thus tending to produce a coun 40 ter-clockwise rotation of the core Il when the winding I5 is energized. The counter-weight I l biases the sector I2 toward a position register ing with the pole piece I, and in Fig. l, the sector I2 is shown as operated against the biasing eflect 45 of the counter-weight Il to a position approxi mately midway between its extreme biased and its extreme operated position in accordance with an intermediate’ degree of energization of the winding IB. The response of the amature arrangement to an abrupt change in current value in the winding II is retarded in the present application by a `short-circuited metallic sleeve 2l. which effects such retardation in the usual manner by retard 55 ing a rapid change in flux within the core I I. It is 50 obvious that various other means may be em ployed in the present device in order to allow the response of the'armature to a gradual change in current in winding I5, but to prevent an immedi ate response to an abrupt change. , insert more resistance into the external electrical circuit. It is contemplated that it will be advantageous to evacuate the glass tube 22. or to provide a reduced pressure of an inert gas therdn before sealingtheglalateachendofthetube 22inthe usual manner. The variable resistor thus formed by the re sistance wire 24 and the mercury globule 20 is shown in Fig. 1 as inserted in series with the bat tery B employed to energize the track circuit shown. A resistor R which is usually employed in track circuits is also shown in series with the battery B, which then forma a normally energized track circuit wherein current supplied by battery B flows through the dxed resistor R., through the variable resistor Just described and through the track rails l in series to normally maintain the track relay TR. energized. The winding Il, as previously stated, is con nected directly across the battery end of the rails l to thereby actuate the variable resistor in ac cordance with the interrail potential at this point. This interrail potential will obviously be the potential of the battery B minus the sum o1' the potential drops through the fixed resistor R and through a portion of the resistance wire 24 which is not shtmted out of the circuit by the mer cury globule 20. Obviously then if the voltage of the battery B is substantially constant, the cur rent in the winding Il will be inversely propor tional to the current through the resistor R and The electro-magnetic operating means just de the resistance wire 24, which current as may be scribed is herein employed to actuate a means for seen above causes the difference between the po varying the resistance of an electrical circuit, and tential across the winding Il and the potential of such a. means is shown in Fig. 1 as a substantially the battery B. square glass tube 22 having a regular longi 1f the leakage current between the rails l of Pig. 1 now gradually increases due for example to increased moisture in the track ballast, the voltage drop between the source B and the relay TR tends to exceed a value permitting reliable operation of the relay TR. but this increased leak 70 tudìnal curvature which is shown as being the same as the shape of the outward edge of the sector I2, and is suitably attached to the outer surface thereof by means not shown in a manner 70 to be rotated by the sector I2. Two triangular strips 23 of insulating material are fitted within the glass tube 22, and each strip is space-wound with a suitable resistance wire 24 as is more clearly shown in Fig. 2. The ends of the resis tance wire 24 are brought out at the right-hand ` age current also reduces the voltage across wind ing Ii due to the increased voltage drop through resistor R and the resistance wire 24, thereby reducing the force tending to rotate the sector I2 in a counter-clockwise direction which allows the 75 ` 2,135,497 counter-weight I9 to proportionally actuate thev ‘ 3| and 32 with suitable bearings, Shown diagram sector I2 in a clockwise direction. ` This rotation matically as fixed members 23 arranged to permit of the sector I2 in a clockwise direction shifts the globule of mercury 26 to a position within the glass tube 22 which shunts out a greater portion of the resistance wire 24 and results in an in vertical movement oi’ the plunger 3U. The ex treme upper end of the upper rod 3i is provided with a brake shoe 84 engageable with the lower -5 edge of the sector I2 when the plunger 30 is op creasedvoltage being applied to the trackrails erated upwardly. The plunger 30 has herein been ' shown as biased toits lower position by gravity, and obviously to .the track relay TR. It is con templated that the characteristics of the presentl 10 regulator can be so chosen that this increased potential is of a value which is effective at the re /15 lay TR to substantially compensate i'or the grad ually increased potential drop fromthe source B to the relay TR, and thereby maintain a substan tially constant energization of the relay TR re gardless of gradual» increase inballast leakage although it is obvious that a spring biasing means may be found more desirable in practice. 10 The actuating coil 28 of the present locking means is connected in multiple with the variable resistor provided by the resistance wire 24 on the sector I2 in Fig. 1, and is thereby energized at all times in accordance with the potential drop 15 across this resistance wire 24. When the track section is unoccupied the resistance inserted into current. It is also'obvious that a converse operation ofl the regulator in Fig. 1 will be produced for ex 20I ample by reduced moisture in the track ballast causing a gradual reduction in ballast leakage current, or that is, a reduced ballast leakage cur rent will increase the voltage across the winding I5 due to the reduced drop between the battery B 25 and the trackrails. This gradually increased voltage across the Winding I5 produces a coun ter-clockwise rotation of the section I2 to move the mercury- globule~26 to a new position _Within the tube 22, which newY position `shunts out less 30 of the resistance wire 24 thereby reducing thek potential applied to the track rails and to the re layfTR. Likewise, it is contemplated thatwhen the regulator is arranged as stated above, this re duction in potential will effect a substantial com 35 pensation for the decrease in potential drop between the source B and the relay TR caused by the gradual reduction in ballast leakage current. However, upon entrance of a train into the track section in Fig. 1, the current supplied by the battery B is quickly increased to a value greatly in excess of normal, which results in an increased voltage drop between the battery B and the relay TR, thereby reducing the voltage the track circuits by various amounts of the wire 24 varies inversely in proportion to the current flowing through the resistance wire 24, which 20 thereby maintains the potential drop thereacross and the current in coil 28 substantially constant, but the locking mechanism is so arranged that this amount of current in coil`28 does not sum ciently attract the plunger 30 to overcome the 25 force of gravity and engage the brake shoe 34 with ‘the edge oi’ the sector I2. ` 'Upon entrance of a train into the track sec tion in Fig. 1, the current through the resistance wirev 24 quickly increases as previously stated, 30 and in as much as the regulator ìdoes not imme diately respond to this rapid increase in cur rent, the sector I2 is not immediately actuated to proportionally decrease the resistance inserted into the track circuit by the resistance wire 24, 35 and the potential drop across the resistance wire 24 and the current in the lock coil 28 is conse quently greatly increased.l This increased current in the coil 28 is now eñective to operate the plunger 30 upward and engage the brake shoe l40 34 with the lower edge of the sector thus pre venting any further movement thereof, aswell as maintaining this increased energization of its across the relay TR to a point effective to release ‘ own coil 28 until the track section becomes un occupied. 45 its armature.` The voltage drop between the bat- ‘ It will now be obvious that the regulator shown 45 tery B and the winding I 5 ofthe regulator in creases at the same time thus reducing the volt age across the winding I5, but the effectiveness in Fig. 1 operates to maintain a substantially constant current in ak track relay regardless of of this quickly vreduced energlzation of the wind ' gradual'changes in current in the track section with which the relay is associated, and only op 50 ing I5 to allow a counter-,clockwise rotation of erates to so regulate the current in the track re 50 the armature and decreases the resistance in ` the track circuit is delayed by the short-circuited lay when such changes in track circuit current are oi’ a gradual nature such as produced by the sleeve 2| until after the track relay TR has re leased its armature. 55 l ' This short-circuited sleeve 2| however can act to retard the effect of the decrease in voltage across the winding I5 upon the armature of the regulator for a short period of time only, which time is found to be less than »the time in >which the train may occupy the track section. In or der to prevent variation of the resistance in the track circuit throughout the time in which the track section is occupied, a locking means has been provided which is effective to maintain a 65 previous position Iof the sector vI2 as long as a train causes the track rails of the associated sec tion to be shunted. ' A rather simple electro-magnetic locking means has diagrammatically been shown in Fig. 70 l and Fig. 2 as an actuating coil 28 which may be enclosed in an iron casing 29, as shown in Fig. 2, with a solenoid plunger 30 positioned in the center ofthe coil 28 and operable upward by energization thereof. The plunger 30 may 75 be provided with upper and lower extending rods effect of changes in weather conditions’vupon the bal‘ast resistance between the track rails. l This distinction between the-rate of change of sa, current allows a train shunt, which results in a very rapid change in current ln the track sec- _« tion, to act in the usual manner to drop the track relay.> In as much as the present means 80 for distinguishing between the rate of changew in track circuit current'can be effective for a short- ». period of time onlyto at times retard a current regulation which would defeat the lpurpose of the track circuit, such a distinguishing means' is herein supplemented by a locking means which,l is operated during the period of time in_whichf the regulator is delayed in responding> to rapid current changes, and is thereafter >effective to prevent any change in the condition of the regu lator as long as a train'shunt is effecting the track circuit. , ' In the modified form of the present invention shown in Fig. 3, the regulating and locking mech anism is placed at the relay end ofjjthe track' 4 2,135,497 circuit instead of the battery end as in Pig. 1, and a modified means is shown for energizing the electro-magnetic lock. The specific means for regulating the current in the track relay as well as the electro-magnetic lock is of a considerable the portion of the resistance rod 4I which is not shunted by the mercury 44, through the mercury 44 to the base 45, and back to the battery B through the upper rail of the track circuit and the usual fixed resistor R1. The left hand ad different construction in Fig. 3 than in Fig. 1 al- ' jacent track section T1 has a similar circuit en though the general operation is the same, and it is desired to be understood that this specific construction is equally applicable to the track 10 circuit arrangement in Fig. 1, and vice versa. The regulator shown in Fig. 3 comprising an actuating coil 35 enclosed by a magnetic casing 36, and actuating a solenoid plunger 31 upward against a biased spring 35. The lower end of the plunger 31 is connected by a rod 55 to a rigid disc 40 which is in turn fixed to the center por tion of a flexible diaphragm 4i. The outer edges of the flexible diaphragm 4| are tightly sealed to a base member 4l by a ring 42 suitably clamped ergizedby battery 1?»J through resistor R.2 and series relay SR1, which relay SR1 closes the en ergizing circuit for signal S1, as indicated dia grammatically by its front contact 55, when track section T:1 is occupied. The wires leading from the regulating and locking means to the track relay and approach relay have been designated a. b, c, d and e, respectively. 'I'he actuating coil 55 of the regulator mecha nisrn is connected in multiple with the track re lay TR1 as is obvious from the drawings, and thereto; the base member 43 being hollowed hav consequently the‘i'orce acting to raise the plunger 31 against the biasing spring Il is in direct proportion to the degree of energization of the ing a small space between the lower surface of the diaphragm 4i and the upper surface of the increased amount of moisture in the track bal track relay TR1. 1f for some reason, such as an base 43.À 'I‘his space beneath the diaphragm 4| is~ last, the potential across the relay TR1 falls be filled with mercury or other suitable current con low its normal value, the voltage across the coil ducting liquid 44, and a small duct 45 in the base member 43 allows the passage of the mercury 44 35 also decreases a proportional amount, thereby allowing the biasing spring Il to force the dia phragm 4I downward which results in raising the level of the mercury 44 in the glass tube 41 to from the space beneath the diaphragm 4I through a small hollow in the base 43 which is covered by a smaller diaphragm 5l ilxed at its shunt out a greater portion of the carbon re~ 30 outer edges to the base member 43 by a suitable sistance rod 4l. ring 5I; which hollow communicates -with a This decrease in the length of the carbon rod second duct 45 leading to the lower end of an .4I which is above the mercury 44 obviously de upright insulating-tube 41. creases the resistance inserted thereby into the It will now be obvious that the relation of the track circuit, and if the characteristics of the present regulator are properly chosen, this de35 force exerted on plunger 51 by coil 35 to the corn pression of spring 38 determines the position of creased resistance will be effective to again raise the diaphragm 4i which in turn determines the the voltage across the track relay TR1 to its nor amount of the mercury 44 which is forced through mal value. The converse operation of the regu the ducts 45 and 46 to raise the level of the mer lator in Fig. 3, or that is, its operation to again 40 cury within the insulating tube 41. A carbon increase the resistance inserted into the track cir resistance rod 48 is sealed within the insulating cuit by the resistance rod 4l in response to an . tube 41 by a suitable cap 49 so that the lower increased voltage at the relay end, is now obvious end of the carbon rod 4l will be submersed in and will not be described in detail. the mercury filling the lower end of this tube, However, when a train, in approaching section 45 and obviously as the level of the mercury within T1, enters section T1, the current in the series the tube 41 changes due to a change in the relay SR1 is suillciently increased to attract its 30 ' 40 45 position of the diaphragm 4I, various portions amature, and thereby energize the locking wind of this carbon resistance rod 4I will be sub mersed, or shorted out, to vary the electrical ing 55 from the battery Bz over an obvious cir cuit completed by front contact 51 oi' relay SR1. The energization of winding 35 operates the valve 50 5I downward closing the end of the duct 45 thus preventing a change in the level of the mercury 44 in the glass tube 41 and consequently pre venting a change in resistance inserted in the track circuit by the carbon rod 4I upon the en 55 trance of the train into the track section T’. 50 resistance between the upper cap 4I of the car bon rod~and the mercury within the tube 41. The locking mechanism in Fig. 3 comprises a rod 52 extending through the center and sealed to the diaphragm 55 with its lower end shaped to 55 form a valve 53, which when operated down wardly closes the end of the duct 45 to -thereby prevent the flow of mercury from the duct 45 into the duct 46. An electro-magnetic means for operating the rod 52 is shown by a coil 55 enclosed within an iron casing 5i and coacting with an armature 51 to operate the rod 52 downward against abiaslng spring 55. The track circuit shown in Fig. 3 is of the well known type in which a series relay SR is employed 65 at the battery end for the purpose of lighting the signals associated with the next track sec tion in advance only when a train enters the track section to increase the current flowing in the series relay SR sufficiently to attract its arma 70 ture, which is again released by the departure of the train. This track circuit in section T3 may be traced from the battery B1, through the series approach lighting relay SR, through the lower track rail, through the track relay TR1 to the 75 upper terminal of the resistance rod 45, through As soon as the train enters section 'P the track relay TR1 drops, and the energizing circuit for winding 55 is maintained closed through a back contact 5I of relay TR1 which is in multiple with the front contact 51 of relay SR1. It will now be seen that the regulator in Fig. 3 is enective to maintain a substantially constant current in the associated track relay regardless of changes in ballast conditions as long as both its associated track section and the section im mediately in the rear thereof are unoccupied. However, in order not to defeat the purpose of the track circuit by allowing the regulator to function in this manner when the section be~ 70 comes occupied, a locking means is energized by the entrance of an approaching train into the section immediately in the rear, which locking means acts to prevent further regulation of the current in the track relay and permitting normal 75 2,185,497 response of this track relay to the train shunt. In order to maintain this locked up condition of the regulator during the occupancy of the track section associated therewith, the energizing cir cuit for the locking means is maintained closed by a back contact of the track relay. In the modified form of the present invention shown in Fig. 3, it is not essential that the regu lator, in itself, distinguishes between a change in accordance with the voltage across the relay TR3, I as previously stated, which current in coil AC 10 voltage across the track relay which is due to a operates to raise the actuating plunger AP against train shunt from a change due to a change in ballast leakage current, as the operation of the regulator in response to a decrease in voltage caused by a train shunt is precluded by the ener the compression springs 12, or to relieve the com pression of the carbon pile variable resistor VR. In other words, the resistance between the top 11 and the bottom 18 oi the variable resistor will be varied in raccordance with gradual variations 15 in the voltage across the track relay TR3. The regulator shown in Fig. 4 then obviously operates 15 gization ot the locking means before the train actually enters the section associated with such track relay. However, inasmuch as it is in tended for the regulator mechanism to respond to gradual changes only in the energization oi’ to maintain ‘a substantially constant current in the track relay TR3 regardless >oi’ gradual voltage 20 the track relay, a check on the initial energiza tion of the locking means may be obtained by changes thereacross in (the same manner as the 20 providing any conventional means which delays »f the response of the regulator to abrupt changes in energization. It is contemplated that the re 25 sponse of the regulator in Fig. 3 to abrupt current changes may easily be delayed by reducing the 5 The effect oi.' a rapid change in the energiza tion of the actuating coil AC upon the plunger AP is retarded in the conventional manner by a short-circuited metallic washer 19 on the lower end of the coil AC, or any other well known retarding means may be employed. Current is sup plied to the windings of the actuating coil AC in other embodiments of vthe present invention pre viously described. -The locking means' for preventing actuation of the regulator in Fig. 4 during the presence of a train inthe associated track section comprises a 25 locking cpll LC which may be energized from a size of the ducts 45 and 46 thereby preventing a local source of energy, such as the storage bat rapid flow of mercury therethrough, or of course y tery B@ ordinarily employed to energize the right a means for delaying flux changes may be pro hand-adjacent track section. A solenoid plung 30 vided in coil 35 in the same manner as in Fig. 1. er LP carried on a non-metallic rod 89 is actu 30 The means for precluding the regulator oper ated by the energization of the coil LC against a ation in response to a train shunt in Fig. 3 takes biasing spring 80. The rod 39 may be supported advantage of the conventional series relay em in any suitable manner to permit longitudinal ployed to approach light wayside signals. movement, such as by the ilexible strips 3i and 35 In the form shown in Fig. 4, a usual insulated 32 held stationary at their lower ends with the track section is provided with a track relay 'I'ii?i upper ends suitably fixed to opposite ends of the 35 ~. normally energized by current flowing through rod 89. 'I'he extreme left hand end of the rod the rails B8 of the track section in series, which 89 carries a frictional braking shoe 83 engage current is supplied by the usual track battery B5 ' able with the side of the rod 89 when the actuat 40 with the conventional fixed series resistor R5. A variable resistor VR is included in series with the track relay TR3, and this variable resistor may be of any suitable type but is herein represented as being of the carbon pile type, which asis well 45 known is made up of carbon discs offering a re ing plunger LP is attracted, but normally held out ot engagement therewith by the spring 80. It is contemplated that, if necessary, the rod 69 may be provided with peripheral serrations or an abraded surface to offer a better gripping surface to the frlctional braking member 83. sistance to the flow of current therethrough which , This locking mechanism operates in somewhat 45 varies inversely in accordance with the compres the same manner as that described in connection sion of these discs. with Fig. 1, but in Fig.k 4 the energizing circuit The compression of the disc oi' the variable for the locking coil LC is controlled through a 50 'resistor VR is shown as automatically controlled back contact 8l of the track relay TR3, so that by an actuating coil AC connected in multiple a train, in entering the track section associated with the relay 'I'R3 to thereby be energized in with relay TR1i is effective to quickly decrease accordance with then voltage thereacross. The the current in the track relay and also the coll actuating coil AC affects a conventionally ar AC, but inasmuch as the response of the plung 55 ranged magnetic solenoid plunger AP, which is er AP to this quickly decreased energization of carried by a non-magnetic rod 69. The rod 89 coil AC is delayed by the washer 19, the track 55 may be supported in any suitable manner to relay TRE* releases its armature before the reg permit free longitudinal movement, such as by ulator can reduce the resistance inserted into the flexible strips 10 and 1|, which strips are held track circuit by the variable resistor VR, and 60 stationary at one end with the other end holding the dropping of the track relay then energizes 60 opposite extreme ends of the rod 69 as shown. The rod 69 is forced downwardly by a com pression spring 12, the tension o1' which spring is adjustable by a. screw 13 threaded through a 65 stationary member 1I with the lower end oi' the screw 13 engaging a washer 15 holding the upper end of the spring 12. The downward force thus supplied to the rod 69 is transmitted through a compression spring 18 to the top 11 of the vari 70 able resistor VR, and inasmuch as the lower member 18 of the variable resistor VR is station ary it will be obvious that, disregarding the action of the plunger AP, the tension of the spring 12 as adjusted by the screw 13 will determine the 75 resistance oi' the carbon pile variable resistor VR. the locking coil LC to cause the braking mem ber 83 to prevent further actuation of the rod 69 as long as the train is occupying the asso ciated track section. In describing the present invention, attention has been directed to one specific embodiment 65 thereof, without attempting to point out the var ious alternate or optional features of construc tion, or the different organizations or combina tions that may be employed. For example, it is contemplated that any one of the speciiic forms» of regulators and locking means shown inthe diiïerent modifications of the present invention may be interchangeably used in any of the dif-ferent track circuit arrangements to form many 75 6 miauw different combinations which have not herein been shown or described. It is also contem plated that a greater safety in track circuit op eration may be provided in the circuits shown in Fig. 3 and Fig. 4 by providing a locking means which is normally energized to permit operation of the current regulating means and from which energy is removed upon the approach and/or presence of a train to prevent operation of the 10 regulating means, and it is considered that the manner in which the present invention could be so modiñed would in view of the foregoing specification be obvious to anyone skilled in the art. In other words, the particular embodiment o1' 15 the present invention has been selected to fa cilitate in the disclosure thereof, rather than to limit the number of forms which it may assume. What I claim is: l. In a track circuit, in combination with an 20 insulated section oi track, a source of electrical energy connected across one end or the insu lated section, and a track relay connected across the other end of the insulated section; regulat ing means arranged to vary the resistance of the connections of said track relay to the track rails and thereby maintain a substantially constant current in the track relay regardless of gradual voltage changes thereacross but to permit cur 30 rent changes in the track relay resulting from relatively abrupt and greater voltage changes thereacross, and means retaining any condition of said regulating means while the track relay is dropped. 35 2. In a track circuit, in combination with an insulated section of track, a source of electrical energy connected across one end of the insulated section, and a track relay connected across the other end of the insulated section; regulating means maintaining a substantially constant cur rent in the track relay regardless of gradual volt age changes across the insulated section by varying the resistance in the track relay con nections, means delaying the response oi’ the current regulating means to an abrupt and re1 atively large decrease in voltage across the in sulated section, and means retaining any condi tion of the current regulating means until the condition causing said abrupt and relatively large 50 decrease in voltage is removed. 3. A railway signaling track circuit, having in combination, an insulated track section, a source of electrical energy connected across a iirst end of the track section, a track relay and a com pressible carbon pile resistor connected in series across the second end of the track section, an electro-magnetic actuator having slower .acting characteristics than the track relay and con nected in multiple with the track relay, means 60 connecting the actuator to the carbon pile re sistor whereby the carbon pile resistor is var iably compressed in direct proportion to varia tions in voltage across the actuator, and an elec tro-magnetic brake operable when energized through a back contact of the track relay to pre vent movement oi the means connecting the ac tuator to the carbon pile resistor. i. In a railway signaling track circuit oi' the class wherein a source of electrical energy is connected across one end of an insulated track current regulating means for varying the resist ance in the track relay connections and thereby maintaining a substantially normal energizing current in the track relay regardless of gradual variations in inter-rail potential at the relay end ,of the track section during an unoccupied condi tion of the track section, and a locking means Preventing a change in condition of the current regulating means when and throughout the time 10 in which the track section is occupied. 5. In'a railway signaling track circuit of the class wherein a source of electrical energy sup plies current through an insulated section of track rails to energize a track relay, the combi nation of a variable resistor and a iixed resistor in series between the source of energy and the rails, an electro-magnetic actuating means con nected across the track rails at the energy end of the track circuit and arranged to vary the resistance of the variable resistor in inverse pro portion to gradual voltage changes in the track circuit, means for retarding the response of the actuating means to an abrupt increase in current in the track circuit, and means for preventing a change in resistance of the variable resistor by 25 said actuating means after an abrupt and rela tively large increase in current in the track cir cuit and as long as said increased current con tinues to flow therein. 6. In a railway signaling track circuit of the 30 class wherein a source of electrical energy supplies current through an insulated section of track rails to energize a track relay, the combination of a variable resistor and a fixed resistor in series be tween the source of energy and the rails, an elec 35 tro-magnetic actuating means arranged to vary the resistance of the variable resistor in inverse proportion to gradual increment changes in the degree oi' the energization thereof, circuit means whereby the actuating means is energized in pro 40 portion to the current through said variable and iixed resistors, means for retarding the response of the actuating means to an abrupt increase in the energization thereoi', and means for prevent ing a change in resistance of the variable resistor 45 after an abrupt increase in current of a predeter mined value greater than any said increment changes through said variable and fixed resistors and as long as said abrupt increase in current con tinues to flow therein. 7. In a railway signaling track circuit, in com bination with an insulated section of track and a source of energy energizing a track relay over a circuit including the rails of the insulated section of track; automatic regulating means adjacent 55 said track relay for maintaing a substantially con stant current in the track relay regardless of grad ual changes in the amount of current supplied by the source of energy, and locking means for pre venting any change in condition of the regulating means when and as long as an abnormal current is supplied by the source of energy providing such abnormal current is obtained abruptly and the amount of change is above a predetermined value. 8. In a railway signaling track circuit of the 65 class wherein a source of electrical energy supplies current through an insulated section of track rails to energize a track relay; the combination of an electro-magnetic regulator arranged to maintain a substantially constant current in the track relay 70 section and a relay is connected across the other regardless of gradual changes in inter-rail leak end thereof to eil’ect the picking up or the drop ping of the relay in accordance with the respec tive unoccupied or occupied condition of the track section by a train, the combination of a age current in the track circuit, and means actu ated by the entrance of a train into an adjacent track section for rendering said regulator ine! fective. 76 2,135,497 9. In a track circuit regulator, an insulating vertical tube, a carbon resistance rod within the vertical tube and connected in the track circuit, means emitting mercury into the lower end of the vertical tube, and an electro-magnetic means en ergized by the track: circuit for varying the amount of mercury emitted into the vertical tube to thereby vary the length of the resistance rod carrying track circuit current, said mercury emit 10 ting means being arranged to retard the response of the electro-magnetic means to an abrupt change in track circuit current. 10. In a track circuit current regulator, an in sulating vertical tube, a carbon resistance rod 15 within the vertical tube and connected in the track circuit, means emitting mercury into the lower end of the vertical tube, an»> electro-magnetic means energized by the track circuit for varying the amount of mercury emitted into the vertical 20 tube to thereby vary the length of the resistance rod carrying track circuit current and an electro magnetic means for at times preventing emission of mercury into the vertical tube. 11. In a regulator for track circuits, two paral~ lel insulating strips, a continuous resistance wire wound on each of the strips and included in the track circuit, an evacuated tube enclosing the strips and included in the track circuit, an evac uated tube enclosing the strips, a globule of mer 30 cury placed within the evacuated tube so as to electrically connect the resistance wire on one oi the strips to the resistance wire on the other of the strips at substantially one point only, and electro-magnetic means energized by the track 35 circuit and moving the evacuated tube in a man ner to shift the mercury globule within the tube to thereby vary the length of resistance wire car rying track circuit current, and to thereby retard the response of the electro-magnetic means to an 40 abrupt change in track circuit energìzation. 12. In a regulator for track circuits, a track circuit including rails, a battery source and a track relay, a field structure having oppositely disposed parallel plane pole faces, an armature 45 having a horizontal core with oscillable plane vanes on the core parallel with and coasting with said pole faces, a stationary winding surrounding said core and energized by said battery source in cluded in the track circuit, and a variable resistor 50 in series in the track circuit and actuated by said armature. ‘ 13. In combination, a track section, a battery source for normally energizing the track section, a track relay associated with the track section, 55 means maintaining a substantially normal cur rent in the track relay regardless of gradual and relatively small changes in interrail potential by varying the resistance of the track relay connec tions, and means precluding the operation of the 60 regulator in response to relatively large changes in interrail potential. 14. In combination, a track circuit, a track re lay included in said circuit, a regulator slower acting than the track relay and arranged to main 65 tain a substantially constant current through the track relay regardless of various weather changes, and a locking means controlled by said track re lay and arranged to prevent a change in condi tion of the regulator whenever the track relay is 70 dropped. . 15. In combination, a track section provided with the usual closed track circuit including a normally energized track relay at one end and a track source of current at the other, a regulator 75 for maintaining a substantially constant current 7 in said track relay irrespective of gradual changes in interrail resistance or track source voltage changes by varying the resistance of the connec tions between said track relay and the track rails, and means actuated in response to a regular train movement for preventing the operation of said regulator in response to a train shunt on said track circuit. 16. In a track circuit, in combination with an insulated track section, a source of electrical en 10 ergy connected across one end of the track sec tion, and a track relay connected across the other end of the track section; a variable resistor- in series with the track relay, an electro-magnetic actuator controlling the variable resistor, means 15 energizing the actuator in accordance with the voltage across the track relay, means retarding the response of the actuator to abrupt voltage changes across the track relay, and an electro magnetic lock operating to prevent a change in 20 condition of the variable resistor when and al ways when the track relay is dropped. 17. In a track circuit, in combination with an insulated track section, a source of electrical en ergy connected across one end of the track sec 25 tion, and a track relay connected across the other end of the track section; a variable resistor in se ries with the track relay, an electro-magnetic ac tuator Icontrolling the variable resistor, means energizing the actuator in accordance with the 30 voltage across the track section, means retarding the response of the actuator to an abrupt decrease in voltage across the track section, and means preventing a change in condition of the variable resistor after an abrupt decrease in voltage across 35 the track section and until said voltage returns substantially to its original value. 18. A railway signaling track circuit, having in combination, an insulated track section, a source of electrical energy connected across a 40 ñrst end of the track section, a track relay and a variable resistor connected in series across a second end oi.' the track section, an electro-mag netic actuator having slower acting characteris tics than the track relay and connected in mul 45 tiple with the track relay, means connecting the actuator to the variable resistor whereby the re sistance of the variable resistor is varied in di rect proportion to .variations in voltage across the actuator, and an electro-magnetic brake op 50 erable when energized through a back contact of the track relay to prevent movement of the means connecting the actuator to the variable resistor. ` 19. In combination, a railway track circuit of 55 the normally energized type, a track relay at one end of said track circuit and arranged to operate on a particular degree of energization, a battery source at the other end of said track cir cuit, a variable resistor included in series in said track circuit at the battery end, means respon sive to the potential across said track circuitat the battery end to actuate said variable resistor to gradually raise or lower the resistance in said circuit so as to maintain said track relay ener 65 gized above said particular degree of energiza tion and below another particular higher degree of energization when gradual changes in poten tial occur within limits of said particular de 70 gree and said higher degree of energization, and means preventing actuation of said variable re sistor when abrupt changes in inter-rail poten tial are caused by the presence of a train in the track circuit so as to -reduce the degree of en 75 8 2,135,497 ergization of said track relay below said particu rails but not allowing opening of said contact due lar degree. to a slow decrease of resistance between said `» 20. In combination; a track circuit including a rails; and locking means for maintaining said section of railway track, a track relay, a battery detecting means in its open contact condition source and a variable resistor all connected in until the resistance between said rails is again series; regulating means responsive to gradual of substantially the same value as existed prior changes in the potential across said track to i'to' said quick decrease of resistance. actuate said variable resistor- in a manner to 26. In combination; a section of railway track, maintain said potential within predetermined limits while said regulating means is active; and means responding to an abrupt change in the inter-rail potential caused by the entrance of a train into the track circuit for rendering said regulating means inactive. 2l. In combination; a track circuit including 15 a section of railway track, a track relay, a bat tery source and a variable resistor all connected in series; regulating means responsive to grad ual changes in the potential across said track to 20 actuate said variable resistor in a manner to maintain said potential within predetermined limits while said regulating means is active; said regulating means being relatively slow acting; and means operable more quickly than said regu 25 lating means and responding to the presence of a train in the track circuit for rendering said regulating means inactive. 22. In combination; a track circuit including a section of railway track, a track relay, a bat 30 tery source and a variable resistor all connected in series; regulating means responsive to the po detecting means for detecting the resistance be tween the rails of said section including a source 10. of current connected across the rails at one end oi said section and an electro-responsive contact controlling means connected in series with said source and across the rails at the other end of said section, said detecting means including means for allowing operation of said contact due to a quick decrease in the resistance between said rails but not allowing operation of said contact due to a slow decrease of resistance between said rails; and means controlled by said contact for 20 maintaining said detecting means in its operated condition until the resistance between said rails is again of substantially the same value as existed prior to said quick decrease of resistance. 2’7. In combination; a section of railway track; 25 tential across said track to actuate said vari able resistor in a manner to maintain said po a source of current connected across the rails of said section at one end of said section; inter-rail resistance detecting means including an electro responsive means having normally closed con tacts and connected across the rails of said sec 30 tion at the other end of said section, said electro responsive means being connected in series with said rails and said source, said detecting means tential within predetermined limits above the including means for causing opening of said con 35 operating potential required for said track relay tacts upon a sudden decrease in said inter-rail 35 provided changes in potential are gradual within resistance but allowing said contacts to remain said limits, and means responsive to an abrupt closed if a gradual decrease in inter-rail resist potential change beyond said limits to render ance takes place; and locking means for main said regulating means inactive. . taining said detecting means in its open contact 23. In combination; a track circuit including condition after each sudden decrease of resist 40 40 Aa section of track, a track relay, a source oi ance until the inter-rail resistance is again of energy and a variable impedance all connected substantially the same value as it was prior to in series; regulating means controlled in accord said sudden decrease of inter-rail resistance, ance with the degree of energization of said whereby said contacts are open during the pres ence of a train in said section. 45 track relay; means rendering said regulating de 45 vice slower in response than said track relay to a 28. In combination; a section of railway track; change in the degree of energization; and means a source of current connected across the rails of allowing said regulating means to operate said said section at one end of said section; inter-rail variable impedance only when said track relay shunt detecting means including an electro-re is picked up. sponsive means having normally closed contacts 50 24. In combination, a track circuit for rail and connected across the rails of said section at roads, a track relay included in said track cir the other end oi said section, said electro-respon cuit, a current regulating device in multiple with sive means being connected in series with said said track relay and slower in its operation than rails and said source, said detecting means in 55 the track relay, a variable resistor controlled by cluding means for causing opening of said con said device for maintaining substantially con tacts upon a sudden increase in inter-rail shunt stant current through said relay of a predeter but allowing said contacts to remain closed if a mined value above the operating value of said gradual increase in inter-rail shunt takes place; track relay, whereby small variations within said and locking means for maintaing said detecting means in its open contact condition after each 60 predetermined value are compensated for but larger variations outside of said predetermined sudden increase in inter-rail shunt until the value deenergize said track relay, and means for inter-rail shunt is again oi substantially the same maintaining said device in its then existing ad value as it was prior to said sudden increase o! justed condition while said track relay is de inter-rail shunt, whereby said contacts are open during the presence of a train in said section due 65 85 energized. 25. In combination; a section of railway track, to the suddenness of application of the train detecting means for detecting the resistance be shunt but are not opened due to a gradually ap tween the rails of said section including a source of current connected across the rails at one end 70 of said section and an electro-responsive con tact controlling means connected in series with said source and across the rails at the other end of said section, said detecting means including means for allowing opening of said contact due 75 to a quick decrease in the resistance between said plied inter-rail shunt as may occur due to a change of weather conditions. 29. In combination; a section oi railway track having two spaced rails; means for supplying an electric potential across said rails at one end of said s_ection; electro-responsive means at the other end of said section connected across said rails and responsive to change its condition in 1l »,ismov accordance with the inter-rail potential at that end; and holding means for preventing a change in the condition or said electro-responsive means when a relatively suddenk decrease in inter-rail potential occurs. said holding means remaining eil’ective until said inter-rail potential increases to the value before such sudden decrease. ' 30. In a. track circuit for railroads. in combi nation with a. source oi current and a limiting 10 resistance connected across the track rails of a track section at one end thereof. circuit control ling means connected acroaa the track rails at the other end of said track section and including a movable element automatically assuming di! !erent positions in accordance with gradual changes in the potential across said track rails, and means responsive to a relatively sudden de crease in the potential across the track rails for maintaining said movable element in its then ex isting position. n OSCAR B. FIEID.