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Lesson26SteeringgearThedirectionoftheshipiscontrolledbythesteeringgear.Astheshipmovesthroughthewater,tileangleoftherudder(舵叶)atthestem(舵柱)determinesthedirectionitwillmove.Modernshiparesobigthatmovingtheruddernecessitatestheuseofhydraulicsorelectricalpower.Thesteeringgearprovidesamovementoftherudder(舵)inresponsetoasignal(信号)fromthebridge(驾驶台).Thetotalsystemmaybeconsideredmadeupofthreeparts:controlequipment(控制设备),apowerunit(动力单元)andatransmissiontotherudderstock(转舵机构).Thecontrolequipmentconveysasignalofdesiredrudderangle(期望舵角)fromthebridgeandactivates(触发)thepowerunitandtransmissionsystemuntilthedesiredangleisreached.Thepowerunitprovidestheforce,whenrequiredandwithimmediateeffect,tomovetheruddertothedesiredangle.Thetransmissionsystemismeansbywhichthemovementoftherudderisaccomplished.Thesteering(操舵)startsatthebridge.therequiredrudderangleistransmittedhydraulicallyorelectricallyfromthesteeringwheelatthebridgetothetelemotor(液压传动操舵装置)atthesteeringgear,justabovetherudder.Thereareafewcommonarrangementsforusinghydraulicpower.Thereare4-rams(撞杆),2-rams(fig.26-1)androtaryvanetypes(转叶式).Theheartofthesehydraulicsystemsisthevariabledeliverypump(变量泵).Thistypeofpumpcanbecontrolledbyjustmovingaspindle(控制杆).Thepumpisdrivenbyanelectricalmotoratconstantspeed.Bymovingthecontrolspindleawayfromthecentralpoint,thepumpstrokeincreases,andthehydraulicfluidispumpedinonedirection.Movingthespindlemorefromthecentralpointwillcausemorefluidtobepumpedandconsequentlymorepressuregeneratedtodrivetherams(撞杆).Movingthecontrolspindlebacktotheoriginalpositionandthenawayintheoppositedirectioncausesthehydraulicfluidtobepumpedinthereverseddirection.Theramswillalsomoveinthereverseddirection.Byusingafloatinglever(浮动杆)feedbackmechanism(反馈机构),whentherudderstock(舵柱)hasreachedthedesiredangle,thepumpcontrollevermovesbacktotheoriginalposition,andthepumpingactionstops.Therudderisstoppedattherequiredangle.Movingthesteeringwheeltotheoppositedirectionwillcausetheruddertocomebacktotheoriginalzeroposition.Certainrequirements(要求)mustcurrently(目前的)bemetbyaship'ssteeringsystem.Theremustbetwoindependentmeansofsteering,althoughwheretwoidenticalpowerunitsareprovided,anauxiliaryunitisnotrequired.Thepowerandtorque(扭矩)capabilitymustbesuchthattheruddercanbeswung(旋转)from35°theothersidewiththeshipatmaximumspeed,andalsothetimetoswingfrom35°onesideto30°theothersidemustnotexceed28seconds.Thesystemmustbeprotectedfromshockingloading(冲击负载)andhavepipe-workwhichisexclusive(专用)toitaswellasbeconstructedfromapprovedmaterials(认可的材料).Controlofthesteeringgearmustbeprovidedinthesteeringgearcompartment(舵机房).Tankersof10,000tonsgrosstonnageandupwardsmusthavetwoindependentsteeringgearcontrolsystemwhichareoperatedfromthebridge.Whereonefails,changeovertotheothermustbeimmediateandachievedfromthebridgeposition.Thesteeringgearitselfmustcomprisetwoindependentsystemswhereafailureofoneresultsinanautomaticchangeovertotheotherwithin45seconds.Anyofthesefailuresshouldresultinanaudibleandvisualalarmsonthebridge.ElectricalcontrolTheelectricalremotecontrolsystemiscommonlyusedinmoderninstallations,andsmallcontrolunitastransmitter(发讯器)onthebridgeandissimpleandreliableinoperation.Thecontrolboxassembly(控制箱组件)ismountedonthesteeringgear.Movementofthebridgetransmitter(发讯器)resultsinelectricalimbalance(不平衡)andcurrentflowtothemotorinthecontrolbox.Themotordrives,throughaflexiblecoupling(柔性联轴节),ascrewshaft(螺杆),causingittoturn.Ascrewblockontheshaftismovedandinturnmovesthefloatinglever(浮动杆)towhichacontrolrod(控制杆)isattached.Thecontrolrodoperatestheslipperring(滑环)orswashplate(斜盘)ofthevariabledeliverypump.Acut-offlever(反馈杆)connectedtothemovingtiller(移动舵柄)willbringthefloatingleverpivot(枢轴,交点)andtheleverintolineatrightanglestothescrewshaftaxis(轴线).Atthispointtherudderanglewillmatchthebridgeleverangleandthepumpingactionwillstop.Forlocalmanualcontrol,theelectricalcontrolisswitchedoffandasmallhandwheelisconnectedtothescrewshaft.Rotationofthehandwheelwillmovethefloatingleverandbringaboutruddermovementasdescribed.SteeringgeartestingPriortoaship’sdeparturefromanyportthesteeringgearshouldbetestedtoensuresatisfactoryoperation.Thesetestsshouldbe:1.Operationofthemainsteeringgear.2.Operationoftheauxiliarysteeringgearoruseofthesecondpumpwhichactsastheauxiliary.3.Operationoftheremotecontrol(telemotor)systemfromthemainbridgesteeringpositions.4.Operationofthesteeringgearusingtheemergencypowersupply(应急电源).5.Therudderangleindicator(舵角指示器)readingwithrespecttotheactualrudderangleshouldbechecked.6.Thealarmsfittedtotheremotecontrolsystemandthesteeringgearpowerunitsshouldbecheckedforcorrectoperation.Duringtheseteststheruddershouldbemovedthroughitsfulltravelinbothdirectionsandandthevariousequipmentitems,linkages(连接),etc,visuallyinspectedfordamageorwear.Thecommunicationsystem(通信系统)betweenthebridgeandthesteeringgearcompartmentshouldalsobeoperated.
本文标题:新版轮机英语unit26-steering-gear
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