轨道交通信号专业英语

轨道交通信号专业英语

曹峰主编

林瑜筠主审

中国铁道出版社有限公司

年北京

2020·

内容简介

本书分为铁路信号技术和城市轨道交通信号技术两部分铁路信号技术部分包括信号继

。

电器信号机轨道电路转辙机等信号基础设备计算机联锁自动闭塞列车运行控制行车

、、、,、、、

调度指挥信号集中监测等信号系统以及驼峰过程控制系统城市轨道交通信号技术部分包

、,。

括概述信号机计轴器交流工频轨道电路等信号基础设备联锁的特殊要求移动闭

,LED、、,,

塞的基本概念的基本原理

,ATP、ATO、ATS,CBTC。

本书可作为铁路信号和城市轨道交通信号专业英语教材

。

图书在版编目(CIP)数据

轨道交通信号专业英语曹峰主编北京中国铁道

/.—:

出版社有限公司

,2020.9

ISBN978-7-113-26811-4

轨曹轨道交通交通信号英语

Ⅰ.①…Ⅱ.①…Ⅲ.①--

Ⅳ.①U284

中国版本图书馆数据核字第号

CIP(2020)066421

书名:轨道交通信号专业英语

作者:曹峰

责任编辑:徐清编辑部电话:电子信箱:

(010)51873147357716058@

封面设计:曾程

责任校对:孙玫

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版次:年月第版年月第次印刷

202091202091

开本:印张字数千

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书号:

ISBN978-7-113-26811-4

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前言

至年底,我国铁路营业里程接近万,居世界第二位;高

201914km

铁营业里程达到万,成为世界上高铁里程最长、运输密度最高、

3.5km

成网运营场景最复杂的国家。我国城市轨道交通营业里程突破

,居世界第一位。我国的高速铁路技术和城市轨道交通技术已

6700km

处于世界先进水平,正在随着“一带一路”走向世界。

伴随着铁路和城市轨道交通的发展,作为铁路和城市轨道交通主要

技术装备的信号系统取得了长足的进步,信号系统的技术装备水平成为

铁路和城市轨道交通现代化的重要保证和主要标志。为了适应铁路信号

技术和城市轨道交通信号技术快速发展的形势,以及走向世界的需求,

编写本书。

本书分为铁路信号技术部分和城市轨道交通信号技术部分,共

20

课。为铁路信号技术部分,包括信号继电器、信号

Lesson1~Lesson10

机、轨道电路、转辙机等信号基础设备,计算机联锁、自动闭塞、列车运行

控制、行车调度指挥、信号集中监测等信号系统,以及普速铁路的驼峰过

程控制系统。为城市轨道交通信号技术部分,包

Lesson11~Lesson20

括概述,信号机、计轴器、交流工频轨道电路等信号基础设备,联锁

LED

的特殊要求,移动闭塞,、、的基本概念,的基本

ATPATOATSCBTC

原理。

每节课都列有主要词汇中英文对照,以及练习题。

本书由南京铁道职业技术学院曹峰主编,林瑜筠主审。南京铁道职

业技术学院田建兆、王锡奎、张菊担任副主编。参与编写的有西安铁路职

业技术学院白宏图,石家庄铁路职业技术学院王明瑾,南京信息职业技

术学院聂睿瑞、朱永宏。曹峰编写、,田建兆编

Lesson1~4Lesson12~16

1

写,王锡奎编写,张菊编写课程。

Lesson5~8Lesson9~11Lesson17~20

在编写过程中,得到许多单位和同行的大力支持和帮助,于此一并表示

感谢。

由于时间过于仓促,加上资料搜集不全,编者水平所限,书中疏漏、

错误、不妥之处在所难免,望读者提出批评和指正,以不断提高书质量。

编者

年月

20203

2

目录

RailwaySignalingTechnology

…………………

Lesson1SignalRelay1

…………

Lesson2Signal8

………………

Lesson3TrackCircuit15

……………

Lesson4SwitchMachine25

……

Lesson5Computer-BasedInterlockingSystem36

…………

Lesson6AutomaticBlockSystem(ABS)43

………

Lesson7TrainControlSystem52

………

Lesson8CentralizedTrafficControl(CTC)62

……………

Lesson9HumpProcessControlSystem68

………………

Lesson10CentralizedSignalingMonitoring(CSM)79

UrbanRailTransitSignalingTechnology

Lesson11TheOverviewoftheUrbanRailTransitSignaling

……………………

System85

……

Lesson12LightEmittingDiode(LED)Signal93

………………

Lesson13AxleCounter99

………………

Lesson14ACIndustrialFrequencyTrackCircuit108

Lesson15FundamentalContentsofUrbanRailTransit

………………

Interlocking114

……………

Lesson16MovingBlock120

……

Lesson17AutomaticTrainProtection(ATP)126

……

Lesson18AutomaticTrainOperation(ATO)133

…

Lesson19AutomaticTrainSupervision(ATS)140

……

Lesson20CommunicationBasedTrainControlSystem(CBTC)147

Lesson1SignalRelay

Signalrelayisageneraltermforallkindsofrelaysinrailway

signal.Relaysarewidelyusedinrailwaysignaltechnology,andrelaysare

indispensablecomponentsofvarioussignalcontrolsystems.

1.Overviewoftherelays

Arelayisanelectricalexcitationswitch,whichisanelectromagnet

withcontacts.Therelayconsistsoftwomainparts:electromagnetic

systemandcontactsystem.Theelectromagneticsystemconsistsof

coils,fixedironcores,ayokeironandamovablemagnetarmature.The

contactsystemincludesmovablecontactsandstaticcontacts.Whena

certainvalueofcurrentpassedcoils,anelectromagneticattraction

producedbyelectromagneticInteractionorinductionmethodattractsthe

magnetarmature.Themagnetarmaturedrivesthecontactsystemand

changesitsstatetoreflectthestatusoftheinputcurrent.

TheelectromagneticrelayisshowninFigure1-1.Whenacertain

valueofcurrentpassedcoils,acertainamountoffluxproducedbetween

themagnetarmatureandironcoregoesthroughtheironcore,magnet

armature,yokeironandairgaptoformaclosedmagneticcircuit.And

thentheironcoreproducesanattractionformagnetarmature.Thesize

oftheattractiondependsonthevalueofthecurrent.Whenthecurrent

increasestoacertainvalue,theincreasingattractioncanbeableto

overcometheresistanceofthemagnetarmaturemovingtotheironcore

'

(mainlythemagnetarmaturesowngravity),andthemagnetarmature

isattractedtotheironcore.Themovablecontactswhicharedrivenby

themagnetarmature(contactsalongwiththemovingmagnetarmature)

alsomove,andconnectwiththemovableclosecontacts(front

contacts).Thisstateiscalledrelayexcitation.

1

Figure1-1thebasicprincipleoftheelectromagneticrelay

Theattractiondecreaseswiththedecreaseofthecurrent.Whenthe

'

decreasingattractionisnotenoughtoovercomethemagnetarmatures

owngravity,themagnetarmaturebyreasonofitsgravitydropdown

(calledrelease).Themagnetarmaturedrivesthemovablecontactsto

disconnectwithfrontcontacts,andthenconnectswithmovablebreak

contacts(backcontacts).Thisstateiscalledrelayexcitation-loss.

Itcanbeseenthattherelayhastheswitchingcharacteristics,which

canbeusedtoconnectandbreakthecircuittoformvariouscontroland

indicationcircuits.

2.Safetyrelay

TheAXseriessafetyrelay,whichisdesignedandmanufacturedby

China,isthemainapprovedproductofChinarailwaysignalrelayand

mostwidelyused.Thesaferelayisaheavyspringtypeelectromagnetic

relayintheDC24Vseries.Itstypicalstructureistheneutralrelay.

Othertypesofrelaysarederivedfromneutralrelays.

Thetypesofsaferelaysincludetheneutralrelay,neutralrelaywith

heavydutycontacts,neutralslowreleaserelay,neutralslowrelease

relaywithheavydutycontacts,rectifyingrelay,polarizedrelay,

polarizedrelaywithheavydutycontacts,polarbiasedrelayandsoon.

Theircharacteristicsandresistancevalueofcoilsaredifferentandthey

2

havedifferenteffectsinsignalcircuits.

Theneutralrelayhasnorequirementforcurrentpolarityofgoing

intothecoils.

Therelaywithheavydutycontactsisdesignedforthesignalcircuit

withhighpower.Thecontactsystemoftherelaywithheavyduty

contactsconsistsofnormalcontactsandheavydutycontacts.Theheavy

dutycontacthasaspecialdesignofthehighpowercontactandmagnetic

blast.Themagneticblastismadeofmagneticsteel,whicheffectsblast

arcusebytheforcedmovementofelectricarcinthemagneticfieldto

maketheelectricarccoolingdownquicklyandquenching.

Theslowreleaserelayhasthefunctionsofslowpick-upand

release.Inspecificcircuits,itiswidelyusedbecauseofitsslowrelease

characteristic.

TherectifyingrelayisusedintheACcircuit.Itturnsalternating

currentintodirectcurrentbymeansoftheinternalhalfwaveorfull

waverectificationcircuit.

Thepolarizedrelayhastwosteadystatesofnormalpositionand

reversepositionaccordingtothedifferentcurrentpolarityincoils.The

twosteadystatesstillcancontinuetokeepwhenthecurrentdisappeared

incoils.Sothepolarizedrelayisalsocalledpolarretainingrelay.Itis

characterizedbytheadditionofpermanentmagneticsteelinthemagnetic

system.Whenthecurrentofspecifiedpolaritypassesthecoils,therelaypicks

upanditstillcankeepthepick-upstateafterbreakingcurrent.Whenthe

currentoftheoppositedirectionpassedthecoils,therelaydropsdownandit

wouldkeepthereleasestateafterbreakingcurrent.

Thepolarbiasedrelayisdesignedtoidentifythecurrentpolarityin

thesignalcircuit.Beingdifferentfromtheneutralrelay,thepick-upof

itsmagnetarmatureisassociatedwiththepolarityofcurrentincoils.

Themagnetarmaturewouldpickuponlywhenthecurrentofthe

specifieddirectionpasses.Itcanbenotactionwhenthecurrentdirection

isopposite.However,itjusthasonesteadystatewhichisdifferentfrom

thepolarizedrelay.Themagnetarmatureispulledupbythe

electromagneticforceanddropsdownafterbreakingcurrent.Itssteady

stateisrelease.

3

3.Timerelay

Thetimerelayisakindofslowpick-uprelay,whichcanbedelayed

bytheelectroniccircuittosatisfytherequirementofsignalcircuits.The

timerelayiscomposedofatimecontrolunitandaneutralrelay.The

timecontrolunitismountedontheprintedcircuitboard,whichis

installedabovethecontactgroup.

4.Filamenttransferrelay

Thefilamenttransferrelaywhichisusedinthesignallighting

circuitisanACrelay.Whenthemainfilamentofthesignallampburns

out,itwillbeautomaticallyconvertedtolightthedeputyfilamentby

thefilamenttransferrelay.Thefilamenttransferrelayisusedtoforman

alarmcircuitbyitscontacts.

5.ACtwo-elementrelay

TheACtwo-elementrelayhastwoindependentandinteracting

alternatingelectromagneticsystems.

ThestructureofanACtwo-elementrelayisshowninFigure1-2.It

iscomposedofanelectromagneticsystem,awingpanel,contactsandsoon.

Figure1-2thestructureoftheACtwo-elementrelay

(Unit:mm)

4

Theelectromagneticsystemincludesalocalelectromagneticsystem

andatrackelectromagneticsystem.Thelocalelectromagneticsystem

consistsofalocalironcoreandlocalcoils.Thetrackelectromagnetic

systemconsistsofatrackironcoreandtrackcoils.

Thewingpanelisthekeycomponent,whichconvertstheenergyof

theelectromagneticsystemintomechanicalenergy.Thewingpanelis

mountedonthemainaxle.

Themovablecontactsarefixedontheauxiliaryaxle.Themainaxle

drivesthemovablerodontheauxiliaryaxlethroughthelinkagetomake

themovablecontactsaction.

Onlywhenthecurrentoflocalcoilsadvancesthecurrentoftrack

coilsacertainangle(preferably90°),therelaycanbeabletopickup

reliably.Ifonlythecurrentpasseseithercoilortwocoilsareconnected

tothesamepower,thewingpanelwouldnotproduceatorquetobe

action.ThisisthereliablephaseselectivityoftheACtwo-elementrelay,

whichcansolvetheprotectionproblemoftherailendinsulation

damage.

Whenthetractioncurrentisunbalanced,ithas50Hzvoltagetobe

addedtothetrackcoils.However,thetorqueforceiszeroinoneperiod.

'

Thewingpaneldonotgeneratetorqueandcantmaketherelayfalse

actionbythemixedinterferencecurrentandthefixed50Hzlocal

currentinthetrackcoils.ThisisthefrequencyselectivityoftheACtwo-

elementrelay,whichnotonlypreventstheinterferenceofthetraction

current,butalsohasthesameeffectonotherfrequencies.

Vocabulary&Phrases

继电器

relay

线圈

coil

铁芯

ironcore

轭铁

yokeiron

衔铁

magnetarmature

5

动接点

movablecontact

静接点

staticcontact

接点系统

contactsystem

安全型继电器

safetyrelay

无极继电器

neutralrelay

缓吸

slowpick-up

缓放

slowrelease

整流式继电器

rectifyingrelay

有极继电器

polarizedrelay

偏极继电器

polarbiasedrelay

时间继电器

timerelay

灯丝

filament

灯丝转换继电器

filamenttransferrelay

交流二元继电器

ACtwo-elementrelay

翼板

wingpanel

牵引电流

tractioncurrent

转矩

torque

Exercises-1

1.Pleasetranslatethefollowingphrasesinthetext.

frontcontact

backcontact

electromagneticsystem

relaywithheavydutycontacts

normalposition

reverseposition

2.Pleasetranslatethefollowingsentences.

(1)Whenthecurrentincreasestoacertainvalue,theincreasing

attractioncanbeabletoovercometheresistanceofthemagnet

6

'

armaturemovingtotheironcore(mainlythemagnetarmaturesown

gravity),andthemagnetarmatureisattractedtotheironcore.The

movablecontactswhicharedrivenbythemagnetarmature(contacts

alongwiththemovingmagnetarmature)alsomove,andconnectwith

themovableclosecontacts(frontcontacts).Thisstateiscalledrelay

excitation.

(2)Thepolarizedrelayhastwosteadystatesofnormalpositionand

reversepositionaccordingtothedifferentcurrentpolarityincoils.The

twosteadystatesstillcancontinuetokeepwhenthecurrentdisappeared

incoils.

(3)Onlywhenthecurrentoflocalcoilsadvancesthecurrentof

trackcoilsacertainangle(preferably90°),therelaycanbeabletopick

upreliably.Ifonlythecurrentpasseseithercoilortwocoilsare

connectedtothesamepower,thewingpanelwouldnotproduceatorque

tobeaction.ThisisthereliablephaseselectivityoftheACtwo-element

relay,whichcansolvetheprotectionproblemoftherailendinsulation

damage.

3.Questionsfordiscussion.

(1)DescribehowtheACtwo-elementrelayworks.

(2)Talkaboutthecharacteristicsofdifferentsafetyrelays.

7

Lesson2Signal

Inordertoindicatethecommandsoftrainrunningandshunting

operation,itisnecessarytosetupallkindsofsignalsandsignal

indicatorsasrequiredintherailway.Theyaretheindispensable

componentsinvarioussignalsystems,whichareusedtoformsignal

displaysforoperatingconditions.

Thecolorlightsignalissignaledbythecolor,number,andstateof

thelighting.

1.Lenscolorlightsignal

Thelenscolorlightsignalhastwotypes:highsignalanddwarf

signal.Thehighsignalmechanismisinstalledonthesignalreinforced

concretesignalpost.Thedwarfsignalmechanismisinstalledonthe

signalcementbase.

Thehighlenscolorlightsignaliscomposedofthepost,mechanism,

bracket,ladderandsoon.Thepostisusedfortheinstallationofthe

mechanismandladder.Eachlamppointofthemechanismisequipped

withacorrespondinglensgroupandaseparatelightingbulbtogive

signaldisplay.Thebracketisusedtofixthemechanismtothepost.

Eachmechanismneedsanupperandlowerbracket.Theladderisusedto

climbandoperateforthesignalmaintenancepersonnel.

Thedwarflenscolorlightsignalwhichiswithoutthebracketand

ladderisfixedonthesignalbasebybolts.

Thecolorlightsignalcanformtwodisplays,threedisplaysand

singledisplay.Allkindsofsignalscanalsohavecalling-onsignal

mechanismsorrouteindicatorsasneeded.

Eachlamppointofthelenscolorlightsignalwhichisshownin

Figure2-1iscomposedofthebulb,lampholder,lensgroup,

8

penthouse,backplaneandsoon.

Figure2-1themechanismofthelenscolorlightsignal

Thebulbisthelightsourceofthecolorlightsignal,whichusesthe

railwaysignalbulbofstraightlinedouble-filament.

Thelampholderwhichisusedtoplacethebulbselectstheprefocus

platelampholder.Thelampholderisfixedafteradjustingthefocalpoint

ofthelensgroup.Thereisnoneedtoadjustwhenchangingthebulb.

Thelensisinstalledontheframebox,whichisinsideofthe

colorfulconvexlens(ithassixcolorsofred,yellow,green,blue,

white,andachromaticcolor),andoutsideofthecolorlessconvexlens.

Thereasonwhytousetwolensgrouptoformtheopticalsystemisthat

itusestheprinciplesoflightrefractionandreflectiontofocusthelight

fromthelightsourcetothedesireddirection,whichwouldenhancethe

lightintensityofthedirection.Inthisway,itcansatisfythesignal

displaydistanceandhasagooddirectionalrequirement.Thecolorofthe

signalmechanismdependsonthecoloredlens.

Thepenthouseisusedtopreventdirectsunlightandotherdirect

lightfromproducingthewrongphantomdisplay.

Thebackplaneisblack,whichmakesupthedarkerbackground.It

cansetoffthebrightnessofthesignallightandimprovethelookout

condition.Onlythehighsignalmachinehasabackplane.Thegeneral

signalusesacircularbackplane.

9

2.Combinationalcolorlightsignal

Thecombinationalcolorlightsignalisusedfortherailwaylineof

difficultlookoutcondition,andsuitableforthestraightlinesandvarious

curvedlineswhosecurveradiusisfrom300mto20,000m.Itcanbe

acquiredcontinuoussignaldisplaywithinadistanceof5mto1,000m

fromthesignal.Thelightsystemdesignofthesignalisreasonable,

whoselightenergyutilizationishighanddisplaydistanceisfar.The

showndistanceofthemainlightsourcecanreach1,000m.ifthepartial

dispersionlensisnotadded,theshowndistancecanreach1,500m.The

'

combinationalcolorlightsignalishelpfulforthedriverslookout,whose

characteristicshavethestrongcurverefraction,bigpartialdispersion

angle,distributedvisiblelight,andhighvisibility.Thereisonlyone

lamproomforeachmechanismofthecombinationalsignal,whichis

assembledintotwodisplay,threedisplayandonedisplaymechanism

respectivelyaccordingtothesignaldisplayrequirements.Therefore,itis

calledcombinationaltype.Thereisnopossibilityofchannelinglight

betweenlamprooms.

Thecombinationalsignalmechanismconsistsoftheopticalsystem,

thefrontsurfaceglass,themechanismshell,thepenthouse,andthe

opticalsightjack,asshowninFigure2-2.

Figure2-2thecombinationalsignalmechanismofXSZ-135type

10

Theopticalsystemofacombinationalsignalmechanismconsistsof

aretroreflector,abulb,acolorpiece,anasphericalmirror,apartial

dispersionlens,andafrontsurfaceglass.Theretroreflectorisan

ellipsoidalmirrorthatfocusesthelightemittedbythelightsource.The

bulbusesthesignalstraightfilamentbulb.Themechanismcanbe

installedpiecesoffivecolors(red,yellow,green,blue,white),which

areabletobecombinedinto20varietiesasrequired.Theaspherical

mirrorisusedtogatherthelight.Thepartialdispersionlensiscomposed

ofmultipleprismsandcurvedmirrors.Itisanopticalelementthat

makesapartofthelightchangeacertainangleaccordingtothedesired

direction.itismadeoforganicglasswithexcellentopticalproperties,

whichhasthecharacteristicsofhighprecision,goodtransmittanceand

stableperformance.Thepartialdispersionlensalsoenhancestheclose

visibility,enablingthesignaltobevisibleat5mfromthesignal.

Inordertopreventthesignalmistakescausedbythereflection,the

frontsurfaceglassofthesignalisdesignedtoleanback15degrees.

Whentheexternallightshinesthesignaldirectly,thereflectedlightcan

bereflectedtothepenthouseabovethemechanismtobescatteredor

absorbed,thuseliminatingthephenomenonofmistakingthesignaldue

toreflection.

Theenclosureofthemechanismismadeofsiliconaluminumalloy.

BothinternalandexternalsurfacesarepaintedwithBerlinblackto

preventlightreflection.Ithasthecharacteristicsofreasonablestructure,

goodsealingpropertyis,smallvolumeis,andlightweightis,each

mechanismincludingthepenthouseweightsabout7kg,whichiseasyto

carryandinstall.

Thepenthouseofthemechanismismadeofglassfiberreinforced

unsaturatedpolyester(commonlyknownasFRP).ithasthe

characteristicsoflightweight,goodcorrosionresistance,andhigh

strength.Itsgeometricalshapeisdesignedtoblockthesunlightand

satisfytheneedofastigmatism.

11

3.LEDsignal

ThesizeoftheLEDsignalmechanismisthesameasthelenscolor

lightsignal。Thesignallightingunitiscomposedoflightemitting

diodes.TheLEDsignaldisplaysystemhasbeensuccessfullyusedasa

newtypeoflightsource,whichhasthecharacteristicsofenergysaving

andmaintenance-free.

ThedisplaydistanceoftheLEDsignalismorethan1.5kmanditis

clearandreliable.Themonitoringcontrolsystemcanmonitorthe

workingstateofthesignal,andthewarningabnormitycanhelpto

accuratelydeterminethefaultpointandfacilitatetimelyprocessing.The

LEDsignalcanbegreatlyreducedinweight,whichiseasytoinstall.it

hasagoodsealingconditionandlongservicelife,whichcanreach105h,

usingtheLEDtoreplacethetraditionaldoublefilamentsignallightbulb

andthelensgroupcaneliminatethefilamentburnout,whichisthe

multiplesignalfailure.ithashighreliability,stablefocus,good

luminosity,noimpactcurrentandnomaintenance.itendsthe

maintenancemethodofreplacingsignalbulbsregularly,whichreduces

themaintenanceworkloadandsavesmaintenancecost.

TheLEDrailwaysignaliscomposedofthesignalmechanismof

aluminumalloy,luminouspanelanditsspeciallightingdevice.

Thesignalmechanismofaluminumalloyisdividedintohighpost

anddwarfmechanism.Thehighpostsignalmechanismconsistsoffour

parts:backplaneassembly,boxassembly,penthouseandsuspension

device.Theinstallationmethodofthedwarfmechanismisthesameas

thelenssignalmechanism.

Theluminouspanelisanewlightsource,whichuseslightemitting

diodes.Theluminouspanelisdividedintohighpost,dwarfandindicator

luminouspanel.Theluminouspanelisacirculardiskwithmanylight

emittingdiodes.

Thespeciallightingdeviceofluminouspanelisanewgeneration

signallightingdeviceforthedevelopmentofluminouspanel.Thedevice

isnotonlystableandreliable,butalsocanbeusedforlargerangeof

12

voltagefluctuation.

Vocabulary&Phrases

信号表示器

signalindicator

矮型

dwarf

机柱

post

机构

mechanism

托架

bracket

梯子

ladder

灯泡

bulb

灯座

lampholder

遮檐

penthouse

背板

backplane

折射

refraction

反射

reflection

非球面镜

asphericalmirror

偏散镜

partialdispersionlens

硅铝合金

siliconaluminumalloy

玻璃纤维增强不饱和聚酯

glassfiberreinforcedunsaturatedpolyester

Exercises-2

1.Pleasetranslatethefollowingphrasesinthetext.

shuntingoperation

dwarfsignal

lenscolorlightsignal

railwaysignalbulbofstraightlinedouble-filament

combinationalcolorlightsignal

lightemittingdiode

2.Pleasetranslatethefollowingsentences.

(1)Thecolorlightsignalcanformtwodisplays,threedisplaysand

13

singledisplay.Allkindsofsignalscanalsohavecalling-onsignal

mechanismsorrouteindicatorsasneeded.

(2)Thereasonwhytousetwolensgrouptoformtheoptical

systemisthatitusestheprinciplesoflightrefractionandreflectionto

focusthelightfromthelightsourcetothedesireddirection,which

wouldenhancethelightintensityofthedirection.Inthisway,itcan

satisfythesignaldisplaydistanceandhasagooddirectional

requirement.

(3)Inordertopreventthesignalmistakescausedbythereflection,

thefrontsurfaceglassofthesignalisdesignedtoleanback15degrees.

Whentheexternallightshinesthesignaldirectly,thereflectedlightcan

bereflectedtothepenthouseabovethemechanismtobescatteredor

absorbed,thuseliminatingthephenomenonofmistakingthesignaldue

toreflection.

3.Questionsfordiscussion.

(1)Talkaboutthestructureofthelenscolorlightsignalandhowit

works.

(2)Thinkofthedifferencesbetweenthelenscolorlightsignaland

combinationalcolorlightsignal.

14

Lesson3TrackCircuit

Thetrackcircuitisacircuitmadeoftherailtrackandrail

insulation.Itisusedtomonitortheoccupancyofthetrackandtolink

thetrainoperationwithsignaldisplays,whichistotransmitrunning

informationtothetrainthroughthetrackcircuit.Thetrackcircuitisthe

importantbasicequipmentofrailwaysignal,anditsperformance

directlyaffectsthetrafficsafetyandtransportationefficiency.

1.Thebasicprincipleoftrackcircuit

Thetrackcircuit,includingtheequipmentsoffeedendand

receivingendusestwosteelrailsastheconductor,andthetwo

terminalsofthetrackhavemechanicalinsulation(orelectrical

insul