US1351771A - lfwis - Google Patents

Description

L. V. LFWIS.

RAILWAY TRAFFI C CGNTRULHNG SYSTEM.

APPUCA EUN FREQ MW. 1, 9 8.

1,351,771 PatentedSept. 7,1920,

Z SHEETS-SHEET 1.

INVENTOR Ma. Attyv L. V. LEWIS.

RAILWAY TRAFFIC CONTROLLING SYSTEM.

Awuumun mm NOV-21.19MB. 1,351,771, Patentedsept. 7, 1920.

2 SHEElS-SHEET 2.

INVENTOFI H Atty.

PE MR em G ler parts in each ofthe views.

I circuit for blotzktB-C con prises the .see

.thereof in claims.

characters UNIT so STA-IE5 PATE T; OFF-ICE.

morn V. cm, or me qnm en; mmmv'mm .essmnon' co m UNIOZlI swnron ESIGHAL commyorswlssvnnn, rmn snvnmn, ,n eonromrron or mlmwxmrnnrrre oomnonnine sirs'rninq Toall'whomitma concern:

Be it known t at I, Lmrn V. LnwrsQn citizen ofv the United States,fresidin 5M3. Edgewood borough, in the county of lo gheny and State ofVZEenns lvnnie, here invented certain new and use n1 Imnrovements in Railway-Trnflla-Cbntrollin *bystems, of. which the following is-nspeei cation.

My invention relates to railway itrafiic controllin systems,-en'd particularly to systems of t e t vpe wherein treiiic governing means locate (in a railway .cenohtrainlis, controlled by energy receired. fromuthe I will describe ":one'iorm of treific controlling s temembody my invention, and W111i; on point out 1: enove'l 'feetnres- In the accompanying tire fing's, Figure! is a diagrammatic view showing one Iform of tracke apparatus embodyin myfixrvention; ig. 2 'is edit-grumble View showing one form of vehlclewerried' epparatus which can be usezl' in coiiperatim v with the treokway apparetnsshown Fig. 1, and also embodying my invention. 3 is 0. View taken on the line III-+111 of Fig. 2 lookingin the direction indicated by the arrows. I

Similar reference characters refer =to-simi- Referrin first to Fig. 1', the reference; R "des'firlete; :the treelr rails. of a. railway; which re are divided zby in-l snlcted' 'omts 2 to form blocks i k-4B,

B- C, 'e c. jTIi'afie' allong :the'ireilrvay is i normally in the direction indicated the;

arrow. v Each block is provided with a. track cir-v cuit comprising as usual the; treckmreils of the block, a. source of alternetin s" sling, current connected across the .lfli-i incentthe exit end ofthe block we -emerg n having a winding c nneGted acrOSsthGr 7 adjacent the entrance end'oi the-block. 'The source of currentfor each track .cir ot q the secondary of ittransfiormer wh'ehfi designated T with an exponentcorrsponl ing to the location end ithe =relayfor each track circuit is des gnated by the reference the-circuit for the primary oftrensformer "Pie from the upper wire of the transmischarncter H an exponent correspond ing to the location. Forexample, the track smmcmu'auamr; Patent.

. flied by n generator 1 or xample, :the circuit ro relay Hfromytheiipgker wire 'of transmission line P "meg-lin erie I I is. flfinfiers'ilbhnli 116' of which constitute the ,in is connected directly with the track mi 5, and the lo'ct'iil 'winding'eis constantly oon nectecl with wtrnnsmision line P to wincholltemeting-signnlin' currentis supnchof these reay s, them, responds to reversals of the relative clarity of the current in the corre- (which I will callnormal-h and to the le when the track circuit is 10f the other pol y which I' will term reverse). These contact fingersoceupy ntermediate or ver-. *ticnlfaos'itions when the track winding of the-re aiy i s-de nergized. V

Theprimei'y o'f eechtrack transformer '1 isTconnected with the transmission line P through-the medin'mof a pole-changer, as "herein e 1 Iained;

1EnclLlJl'O0klS provided with t second remy which is .des'igneted by the reference character D with an exgonent correspondingfto the location of t e relay. Each of 7 these relays D is controlled by contact. 6

of the track re'laly .H atfthe same location.

'the control being such that relay Dis energiz'e'd wh el-.118 track relayis cnergizedm either direction, but-that relay D is clefinerwhenathe truck relay is 'cleiner igecl. 1s

throli h wires 9 and 1.3,ebntect6, wirell),

"r'el 'y fiend wires" 11 and 112-to the lower wire. of 'the transmission line. It will be;

noted that contact 6 is closeii when track re in *JHPis ener ea in either direction.

itheprimnry of the adjacent trans oimer T.

For example, when relay D", is energized,

sion line-f, throughwires 9 and .18, upper spon ing track circuit with respect to that of-the'trensmission line P, so thatthe con- 'tectfin ere-6, 7 andi8 ereswung tothe right point of contact 16, wire 19, primary of transformer T wire 20, upper point of contact 15, wires 21, 22 and 12 to the lower wire of the transmission line P. When relay D is deener ized, the circuit for the primary of transiormer T is from wire 9,

throu '11 wire 18, lower point of contact 15,

wire 30, primary of transformer T, wire 19, lower point of contact 16 and wire 22 to wire12. hen relay D is energized, the current which is supplied to the transformer T is 0? normal polarity, that is of such polarity that relay H" is energized in the normal direction. When relay D' is dciinergized, current or reverse polarity is supplied to transformer T, so that relay H" is encr ized in the reverse direction.

it follows from the foregoing that the track relay H for a block immediately in the rear of an occupied block is energized in the reverse direction. and that the track rcla I for a block in the rear of the unocclb pie block is energized in the normal direction. 26 Means are provided for each block for supplying a second alternating current thereto, which current flows in the same direction in both rails of the block. This current is supplied by a. transformer located at the entrance end of the block and designated by the reference character U with an exponent corresponding to the location. The primary of each of these transformers is connected directly with the transmission line P. This current is led into the track rails through connections at the middle points of resistances which are connected across the rails and which are designated by the reference character M with suitable exponent-s and subscripts. Three of these resistances a re provided for each block, two of which are located at the o )posite ends of the block and the third at an intermediate oint 'in the block designated E. The point E in each block is located adistance in therear of the exit end of the block substantially equal to the maximlun braking distance of-a train traveling at an intermediate speed, which speed, as hereinafter chosen arbitrarily, is 35 miles per hour. Each block is, therefore, divided by the point 1*] into a forward sec tion and a rear section; thus the forward section for block B--C is section E('l, and the rear section is 3-1).

The so ply of current from each transformer U to the rails' of the cones )ondin" block is controlled by contact 8 of t e trash relay for the same block, and by contact 14 of the relay D for the block next in advance. Contact 8 of each track relay is arran -d to be closedwhen the relay is deiinergize but to be open when the relay is energized in either normal or reverse direction. When relay D is energized, and relay D deiiner so gized,'current from transformer U is sup- Iplied to the rails of block B-C, the circuit eing from the secondary of transformer U, through wire 23, non-inductive resistance 24, contact 8 of relay H wire 25 to the middle point of resistance M here the current dirides and flows through the two halves of this resistance in opposite directions, through rails R and R 111 multiple, the two halves of resistance 'M", in opposite directions to the middle point of this resistance; thence through wire 26, upper point of contact .14 of relay 1)", and wire 27 to the secondary of transformer U. When relay D is. definergized, however, the current from transformer U passes through wire 23, reso sistance 24, contact 8, wire 25, resistance M rails R and R in multiple to pointE, thence throu h the two halves of resistance M wire 28, ower point of contact 14, and wire 27 to transformer U. It will be seen, therefore, that when the relay D for any block is energized, and the block in the rear is occupied, current from the transformer U is supplied to the track rails of the block in the rear throu hout the entire length of such block; but that when the relay D for any block is deenergized and the block in the rear is occupied, current from the transformer U is sup lied to onl the rear sectien of the block in the rear, 1; mt is, from the entrance end of such block to the point It. It will further be seen' that current from the transformer U of any block is suppliedto the rails of such block only when relay H for such block is deenergized; that is, only when a vehicle has entered the block.

From the for wing it will be seen that menus are provi ed for each block For supplying two superimposed alternating signaling currents to the rails thereof, one of which currents flows in op iosite directions in the two rails, while the other current flows in the same direction along the rails. An inductive reactance 3 is included in the secondary circuit of each transformer T, and a non-inductive resistance'24 is included in the secondary circuit of each transformer U, so that the currents from the two sources are preferably displaced substantialllly 90 in phase in the track rails. The rest taut total current in one rail is, therefore, approximately equal in amplitude, hut diflfers widely in phase from the current in the other rail. Since the local winding 5 and the track windin 4: of the track relay H, which is 120 prefers. 1y of the usual induction motor type are inductive, the current through locai winding-5' will lag behind the eiectromotive force of the transmission line, and will require ale of morethan 90 in the current 125 in the tree r winding s to the phase displacemeet between the currents in the two relay windin required for the most eflicient operation o the relay. Non-incluotive shunt resistance M, connected across winding 4 per- 13 0 mits the current in the inductive branch circuit 4 to lag a greater amount than the resultant current in the track rails from transformer T, which current, by reason of the reactance of the track rails and the non inductive shunt resistance M, will lag a greater amount than the total current through reactance 3, which total current will lag behind the electromotivc force of the transmission line. That is, by connecting non-inductive resistances M across the track rails the angle of lag of the track circuit current in the track rails and through the track relay may be increased, and within limits maybe varied b changing these resistances, so as to secure edcient operation of the track relay and likewise so as to produce a large ang e of lag in the track circuit current in an occupied block so as to secure etlicient operation of certain vehicle-carried apparatus hereinafter described. As is evident, the leakage conductance between rails may in wet weather produce an effect similar to resistances M, but the presence of resistances M stabilizes this effect and renders the track circuit less variable with changes in weather conditions and secures the advantageous conditions of operation under all weather con ditions.

Located at the entrance of each block is a roadside signal which is designated by thereference character S with an exponent corresponding to the location of the siwnal. As here shown, these signals are of the type known as light signals, each cornprising three electric lamps'G, Y and R, indicating proceed, caution and stop, respectively when illuminated. Each signal S is controlled by contact 7 of the adjacent track relay H, and by contact 17 of the adjacent relay D. This control is such that when the track relay is energized in the normal direction, the green lam G is illuminated so that; the signal indicates proceed; when the track relay is ener ized in reverse direction the yellow lamp Y is illuminated so that the signal indicates cautil)? 3 and when the track relay is deenergizcd, the red lain R is illuminated so that the signal indicates stop. As here shown, the circuit for the proceed lam G (see signal S is from wire 9, throng the upper point of contact 17, wire 29, right-hand point of contact 7, wire. 30, lamp G, and wire 31 towire 12'. The circuit for the caution lamp Y is the same as the circuit just traced for lamp G, except that it includes the left-hand point of contact 7 and wire The circuit for the red lamp R is from wire 9, through the lower point, of contact 17, Wire 33, lamp R, and wire 31 to wire 12.

Referrin now to Fig. 2, the reference character T desi ates a railway vehicle (a car or train), w 1ich.is represented by two axles and two pairs of wheels. Mounted on this vehicle in advance of] the forward axle are two laminated soft iron cores 34 and 34, located over the two track rails respcctively (see also Fig. 3), each core being U-shapcd with its legs. pointing downwardly, and each core being disposed trans versely with respect to the rail. It is up parent, therefore, that when alternating current flows in either rail, part of the magnetic lines of force surrounding such rail will pass through the core which is directly over the rail, and so will induce an alterhating potential in any coil which the core ma carry.

(acre 34 is provided with two coils 35 and 36, and core 34 is similarly provided with two coils 35 and 36*. Coils 3.3 and 35 are connected in series in a circuit a. which circuit is from coil 35, through wire 37, condenser 38, wires 39 and 40. coil 35 and wire 41 to coil 35". The coils :55 and 35 are connected in this circuit in such manner that the potentials created in these coils by alternating current flowing in opposite d1- rections in the two rails are additive, while the potentials created in these coils by currents flowing in the same direction 111 the two rails oppose each other and so cause no current in circuit a. Track circuit currcut from transformers T, therefore, induces current in circuit a, but the current supplied by transformers U produces no current in this circuit.

Coils 36 and 36 are connected in series in circuit b. which circuit is from coil 36, through wire 42, condenser 43, wires 39, 40 and 44, coil 36, and wire 45 to coil 36. The coils 3G and 36 are connected in this circuit in suchmanner that the potentials created in these coils by currents flowing in the same direction in the two track rails are additive, but. that the potentials created in these coils by currents flowing in opposite directions in the two track rails opposeeach other. It follows, then, that current from the transformers U flowing in the track rails will induce a current in circuit I), but that no current will be induced in this circuit by track circuit current in the rails from the transformers T Coils 35 and 35 are so wound as to have high inductance, and condenser 38 has comparatively small capacity, and the circuit including those. elements (circuit a) is tuned to resonance at the frequency 'of the signaling current, hence condenser 38 will be charged to a comparatively high potential by the comparatively feeble cu rrcnt induced in circuit a by current in the track rails. Circuit 7) is also tuned to resonance at the signaling current frequency. with similar results. It follows that when the vehicle V occupies a block in which Fig'fiullng currents are supplied to the track rails by transformers T and ll, currents will flow in circuits (1 and 7) on the vehicle. and these currents will be of the same frequency as. and will have the same phase ilispl: *Pilltllt as. the two currents in the track rails respcctivclr. These currents. and the consequent potentials impressed on condensers its and 41%. are. ho ever. too feeble to reli ably actuate traliit governing a )paratus of a rugged ch tcr. hence I pret erably pro- \ide suitable iuplit'ying apparatus. which. in the form re shown. comprises electron tubes K. K". i i and K. Each oi these electron tubes (see ii) comprises a vacuum tube 41' LUlllllillll'lg a filament ill, a plate il and a grid interposed between the two. The filaments l8 oi these electron tubes are constantly heated by a l'iattery 46 through circuits which will be obvious from the drawing.

(11116811550? 3% of circuit rt is connected ZUTUSS the lilamcnl l and grid so of electron tube K. a blocking condenser 51 being inrluiied in the circuit. The plate circuit of electron tube lie is l'roni plate 49. through uirc 5:1. prinmrr of transformer 53. wires .14 and 55. the generator i oi a motor Jeneratrn' '11. and wires ll? and oil to filament i of electron tube ii. The motor M of the motor generator Z is constantly operated by the battery iii. The secondary of transformer oil is connected across the filament and grid of the electron tube K. The plate circuit of this latter electron tube is iron; thc plate iii. through wire on, winding .5? of a relay F. wires 59 and 53; generator (i. wires 39 and (ill. filament of electron tube K. and wire til to filament of electron tube K (onnected across relay winding 5? a condenser 58. the circuit comprising condenser 5 and winding 5? being tuned to resonance at the frequency of the signaling current. It will be seen. therefore. that relay winding 57 is supplied with current of the same frequency as that which is supplied to the track circuit, but that this current is of considerably greater magnitude than that induced in circuit a and so is of suilicient value to reliably actuate an electromagnetic or induction motor relay of rugged design.

The current induced. in the vehicle-carried circuit 1) is similarly amplified by the two electron tubes K and K. the plate circuit of the latter electron tube being from the plate of the electron tube through wire 62. winding 63 of relay F, wires 59 an( 55, generator G. wires 39 and 64. filament of electron tube K and wire 65 to the lilament of electron tube Ki (onnected across relay winding 63 is a condenser 66, the circuit including this winding and condenser being tuned to resonance at the frequency of the signaling current. i l inding; 63 is. therefore, supplied with current of the same frequency as the current supplied to the track rails by the transformers l. but the current in. Winding til is. of course. of coin siderably greater magnitude than that which flows in circuit 5.

The relay i is of the induction motor comprising a rotor member (37 which "its to rrents displaced in phase in ling: T and 63. and which. in turn. aetuates contart members 68 and (i9. lnas much as the two currents in the track rails are displa ed in ihzise. it follows that the currents in relay windings 5? and 63 will similarly be displaced in phase. So that torque will be exerted on the rotor member (3? in one direction or the other, depending on the relative instantaneous polarities of the currents in the track rail- In other words, contact members (38 and 69 will be swung to. the right or the left from their middle position to which they are biased. according: as the track circuit current from transformer T of normal or reverse polarity.

Relay i controls a relay l in such manner that the latter relay is energized when relay F is energized in either direction, and that relay E1 is deenergized when relay l. is de nergicied. The circuit for relay L is from battery iii. through wires T0. 71. T2 and T3. contai' t (if of relay F. wire 74, relay 1.. and wires 75. Tl: and 39 to battery -16.

The relays l and T1 may be employed to control any kind of tra ic governing apparatus that may be desired. As here shown. these relays control a cab signal S and speed controlling apparatus which two devices I will now describe.

The signal Scomprises three incandescent lamps G, Y and R. which lamps, when illuminated, indicate proceed: caution and stop, respectively. The control of this signal is such that when relay F is energized in the normal direction. lamp (l is illuminated so that the signal indicates proceed; when relay F is energized in the reverse direction. lamp Y is illuminated so that the signal indicates caution and when relay is denergized lamp R is illuminated so that the signal indicate. stop. The circuit for lamp G is from battery 46, through wires 70, 71 and 72, upper point of contact 77 of relay L. wire 78, right-hand point of contact 68. wire 79, lamp G, and wires 80 and 39 to battery 46. The circuit for the caution lamp Y. is the same. except that it includes the left-hand point of contact 68 and wire 81. The circuit for lamp R is from battery 46, through wires 1'0, 71 and 72. lower point of contact 7?, wire 82. lamp R and wires 80 and 39 to battery 46.

The speed controlling apparatus V is governed by two relays J and J", which relays are in turn controlled by relays F lll but the current supplied to circuit o will be of reverse polarity. so that rela F Will hecome energized 11] the reverse direction. Signal S will then indicate caution and the trailic governing apparatus il will cause the speed of the vehicle to ho hrought down to the intermediate value, such as 35 miles per hour. whereupon the vehicle may then proceed at or helon' this speed. ,Vhen the vehicle passes point I11 in this Mock. the suppl of current to circuit F; will he discontinueiL so that relay 1* will become dcenergizcd. Signal will then change to stop indi cation and the governing apparatus ll will cause the speed of the vehicle to he reduced to if miles per hour, whereupon the vehicle may then proceed at or below this speed. As the vehicle Y passes location C, the supply of current to circuit 1: will he discontinued. hecaase the track circuit current will he cut oil by the u'liccls and axles of the rehiclc Y in the same block in advance of vehicle i so that even though current will then he supplied to circuit i relay P will continue to he deencrgized and the conditions of signal S and governing apparatus ll will not he changed.

Although I have herein shown and dcrihcd only one form of apparatus embodying my lIiVQDtlGIL it is understood that rarions changes and modifications may be made therein within the scope of the up pendcd claims Without departing from the spirit and scope of my invention.

Having thus described my what I claim is:

1. Rnilwa trallic controlling a 'i-parzitus comprising track rails, a source of alternating signaling current connected across said rails two non-inductive resistances coiniccted across said riils at different points, a sccond source of alternating signaling current the terminals of which are connected with the middle points of said resistances and \'Ql1lt'l-C3I'FlQtl tratlic governing means controlled. by the two currents in said track rails.

32. Railway traffic controlling apparatus comprising track rails a source. of alterhating signaling current connected across said rails two non-inductive resistances connected across said rails at difi'crent points a second source of alternating signaling current the terminals of which are connected with the middle points of said resistances, means responsive to tratlic conditions in advance for reversing the polarity of one of said sources, and vehicle-carried tratlic governing means controlled by the two currents in said track rails.

c 3. Railway trafiic controlling apparatus comprising track rails a source of alternat in signaling current connected across said rails through an inductive rcactance, two

invention,

non-inductive resistances connected across said rails at different points, a second source of alternating signaling current connected with the middle points of said resistances through a third non-inductive resistance and vehicle-carricd traflic governing means controlled by the currents flowing in the t rack-rails.

4. Railway traffic controlling apparatus comprising track rails, 21 source of alternating signaling current connected across said rails through an impedance, two non-inductive resistances connected across said rails at different points, a second source of alternating signaling current connected with the middle points of said resistances through a third non-inductive resistance, and vehiclecarricd traffic governing means controlled by the currents flowing in the track rails.

5. Railway trafiic controlling apparatus comprising track rails, two n0n-indnctire resistances connected across said rails at different points, a source of alternating signalin currents the terminals of which are connected with the middle points of said resist ances. and vehicle-carried trafiic governing means controlled by the current flowing in the track rails from said source.

6. Railway tratlic controlling apparatus comprising a railway track divided into blocks, a source of alternating signaling current connected across the track rails of each lilock adjacent the exit end thereof, means for each bloclr controlled by tratlic conditions in advance for reversing the po larit of said source; three resistances for each lllfltk connected across the rails thereof at, respectively the entrance end, the exit; end and an intermediate point in the block, a second source of alternating signaling current l'or each block one terminal of which is connected with the middle point of the ro sistancc at the entrance end of the block means toncach hlock controlled by traflic conditions in ad ance for connecting tho other terminal of the second source with the middle point of the resistance at the exit end or with the middle point of the resistance at the intermediate point in the block, and vehiclwcarried tratlic governing means controlled by the two currents in the track rails.

T. Railway tratlic controlling apparatus comprising a railway track divided into lilocks. means for each block controlled by tratiic conditions in advance for applying an alternating diil'ercncc of potential of one olarit or the other across the rails adjacent the exit end of the block, means for each block controlled also by traflic conditions in advance for applying a second alternating difference of potential alon the rails from tho entrance end of the block to an intermediate point in the clock or to the exit end of the block, and vehicle'carried trafiic governin means controlled by the two currents in said track rails.

8. Railway trafiic controllin com rising a railwa track ivided into bloc two sources 0 alternating si alin current for each block, means for eac bloc controlled by traffic conditions in advance for connecting the terminals of one source across the rails at the exit end of the block in one direction or the other, means for each block for connecting one terminal of the other source with both rails at the entrance end of the block, means for each block controlled by traflic conditions in advance for connecting the remaining terminal of the latter source with both track rails at an intermediate point in the block or at the exit end of the block, and vehicle-carried trailic governing means controlled by the two currents in said track rails.

9. Railway traflic controllin apparatus comprising a railway track ivided into blocks, a first source of alternating signal ing current for each block connected across the track rails at the exit end of the block, a track relay for each block connected across the rails at the exit end of the block and responsive to reversals of olarity of the said first source of current or the same block, a second relay for each block controlled by the track relay for the same block and arranged to be energized when the track relay is energized in either direction but deener ized when the track relay is deenergize the contacts of said second relay for each block constituting a pole-changer for the said first source of current for the block next in the rear, a second source of current for each block, means for each block for connecting one terminal of said second source with both track rails adjacent the entrance end of the block, means for each block for connecting the remaining terminal of the second source with both rails adjacent the exit end of the block or at an intermediate point in the block according as the second relay for the block next in advance is energized or'deenergized, and vehicle-carried traflic governing means controlled by the two currents in said track rai s.

10. Railway traffic controlling apparatus comprising track rails, means for supplying two alternating signaling currentsthereto one of which flows in opposite directions in the two rails and the other of which flows in the same direction in the two rails, a vehicle, two soft iron cores thereon located over the two rails respectively and dis ,osed transv sely with respect to the rai s; a

apparatus circuit on the vehicle including a coil on each of said cores which coils are so c )l'lnected in the circuit that the potential, induced in said coils by currents flowi 1g in the same direction in said rails are additive, a second circuit on the vehicle including another coil on each core which coils are so connected in the circuit that the potentials induced in the coils by currents'fiowing in opposite directions in the track rails are additive, and vehicle governin means controlled by the currents in sai two circuits.

11. Railway traflic controlling apparatus comprising track rails, means for supplying alternating signaling current thereto whereby the current in one rail differs in base from the current in the other rail, a ve icle, two laminated iron cores thereon located respectively over the two rails and disposed transversely with respect to the rails; a circuit on the vehicle including a coil on each of said cores connected in the same direction, a second circuit on the vehicle including a second coil on each core connected in opposite directions, and vehicle governin means controlled by the potentials induce in said two circuits y the current in the two track rails.

12. In combination, a section, of railway track, a track circuit including a source of current and a track relay both of which are connected across the rails of said section, a second circuit including the two rails of said section in multiple, and means comprising a contactof said track relay for opening said second circuit when the rela is energized.

13. Railway trallic controlling apparatus comprising means for supplying a plurality of alternating currents to the track rails, means controlled by trafiic conditions in advance for reversing the relative polarity of one of said currents under caution cond1- tions, and for discontinuing the supply of one of said currents under stop conditions, and vehicle carried apparatus re uiring a constant supply of energy from t e track rails to prevent a brake application, said apparatus being responsive to the reversal of relative polarity of said one current by applying the brakes if the speed is above a given medium value, and to the cessation of one of said currents b applying the brakes if the speed of the ve icle is above a given low value.

In testimon whereof I afiix my signature in presence 0 two witnesses.

LLOYD V. LEWIS.

Witnesses:

A. Human Wnorvna, E. P. CRUM.

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