Lesson19Cargohandlingequipment(货物装卸设备货物装卸设备)Thevariousitemsofmachineryandequipmentcanbefoundoutsideofthemachineryspace.Theseincludedeckmachinerysuchasmooringequipment(系系缆缆 设设 备备 ), anchor handlingequipment(抛抛锚锚设设备备), cargohandlingequipmentandhatchcovers(舱口盖舱口盖).Other items include lifeboats(救救生生艇艇)andliferafts(救救生生筏筏),emergency equipment,watertight doors,valveactuator,stabilizers(减减摇摇装装置置)andbow thrusters(船船头头推推进进器器).Thecargohandlingequipmentwillnowbedescribed.Cargo winches are used withvariousderrick(吊吊杆杆)systemsarrangedforcargohandling.Theunitisratedaccordingtothe safe working load to be liftedandusuallyhasadoublespeed provision(装装 置置 ) whenworkingathalfload.In the cargo winch, spurreductiongearingtransfersthemotordrivetothebarrelshaft.A warp end(卷卷绕绕端端) may befittedforoperatingthederricktoppinglift(顶顶牵牵索索)(thewirewhichadjuststhederrickheight).Manuallyoperatedbandbrakes may be fitted and thedrivemotorwillhaveabrakearrangedtofail-safe(故故障障保保护护), i.e. it will hold the load ifpower fails or the machine isstopped.Aderrickrig(装装置置)isknownas union purchase(双双杆杆联联吊装置吊装置).Onederrickispositionedoverthe quayside and the otheralmostverticallyoverthehold(货舱货舱).Toppingwiresfixtheheightofthederricks andstays(稳稳索索)to the deck may be used topreventforeandaftmovement.WinchesDerricksToppingwiresCargohandlingwiresCargo handling wires runfromtwowinchesandjoinatthehook.A combination of movementsfrom two winches enableslifting,transferringandloweringofthecargo.Craneshavereplacedderricksonmanymodernships.Positioned between the holds,oftenonaplateformwhichcanbe rotated through 360, thedeckcraneprovidesanimmediately operational unitrequiring only one man tooperateit.Varioustypesofcraneexistforparticularduties.Inageneralcargocrane,threeseparate drives provide theprincipalmovements:a hoisting(起起 升升 ) motor forliftingtheload,aluffing(变变幅幅)motor for raising or loweringthe jib(boom), and a slewing(旋旋转转)motorforrotatingthecrane.Thecraneisusuallymountedon a pedestal(底底座座) to offeradequatevisibilitytotheoperator.For occasional heavy loads,twocranescanbearrangedtoworktogether.The operating medium fordeck crane motors may behydraulicorelectric.Theuseofhydraulicdrivesin cranes, winches and similar equipmentisnowacceptedasaconventional method of driveinmanycase.Manyreasonscanbesuggestedfortheuseofhydraulicsystemsinmarineengineering:a) A convenient method oftransferringpoweroverrelativelylongdistancesfrom,say, a central pump room toremoteoperatingsites.b)Fullyvariablespeedcontrolof both linear and rotarymotion, with good inchingcapabilityandsmoothtakeupofload.c) High static forces ortorques can be achieved andmaintainedindefinitely(无无限限期期地地).d)Completesafetyandreliabilityisassuredunderthemost difficult environmentalconditions;overloadconditionsaresafeguarded by using a reliefvalvetolimitmaximumoutputtorquesorforces.Thewiderangeofhightorque,lowspeedmotorsareavailablefordrivingwinchdrumsdirectly so dispensing with(免免 除除 )theneedtofitreductiongearing.Motors of this type are morecommononlargercraneswherereductiongearboxeswouldbeexpensive.All fixed capacity motors,whether high or low speed,require a high flow at lowpressure to obtain high lighthook speeds and consequentshortcycletimes.With large cranes this canbecomeanembarrassmentandonesolutionwith low speed motorsistousethetwospeedtype to double the speed andhalftheoutputtorqueatlighthookload.Highspeedmotorswithreduction gearing have theadvantagethat the brake can be mounted on the high speed shaftandsobemuchsmallerandcheaper.Because of the availability ofstandard low cost gearboxesthisarrangementispopularonlightcranes.Variable capacity axial pistonmotorshavetheimportantadvantagethatlighthookspeedscanbeincreaseduptofourtimesfromagivenoilflowbyreducingthemotorcapacityto25percentofthemaximum.Hydraulic Crane The hoisting of the cargo iseffected by a hoisting winchdrivenbyahydraulicmotorthatthatprovidesaconstanttorquein both directions of rotationand at all speeds within theregulationrangeofthemotor.Thewinchisequippedwithamechanical belt brake thatacts on the outside of therotatingmotorhousing.Duringoperation,thebrakeisreleased by means of oilpressure which compresses aspring.The crane jib is raised andloweredbymeansofaluffingwinchwhichisconstructedinasimilarmannertothehoistingwinch.The pumps are axial pistonpumps and are driven by acommon3-phasedsynchronous motor(三三相相同同步步电电动动机机)ataconstantspeedofrotation.The capacity of the pump ischangedbyturningtheswashplate.The crane is turned by ahydraulic motor of the sametypeasthatdescribed above,inthat the rotor turns a pinionwhich engages with a toothedringonthecranehousing.Anoilcoolerisusedtoremovethe heat generated in the oilduring the operation of thecrane.The system is also providedwith a preheater for heatingtheoilincoldweather.If the temperature of the oilreaches85oC,athermostat(温温度度调调节节装装置置)in one of the oil lines switches off the electricmotor.Pressurereliefvalvesarebuiltintothesystemtoprotectthesystem and the crane againstexcessiveloads.Allmovingpartsinthehydraulicsystemarelubricatedbymeansoftheoilinthesystem.Thecranehousing,whichisaweldedconstructiononarigidbaseplate, contains all themechanicalmachinery,thehydraulicsystemandtheelectricequipment.Thetopsofthecranehousingandthejibcarryblocks(滑滑轮轮组组)forwiresforthehoistingofthecargoandtheraisingofthejib.Alloftheblockshaveenclosedballbearing.Boththeluffingwinchandthewinch for turning the craneare operated from the samecontrolhandle.A small movement of this control handle either forwards or backwards results in thebuildupofoilpressureinthecontroloillineandthepistonin the brake cylinder releasesthebrake.Movementofthecontrolhandlefurtherthanthepositionforreleasingthebrakestartstheluffingwinch.The crane jib is raised orloweredbymovingthecontrolhandlebackwardsorforwardsrespectively.The speed at which the jib is raised or loweredisproportional to the distancethehandleismoved.Changesinspeedareeffectedby changing the pressure ofthe oil that is supplied to thecontrol cylinder and whichregulates the pump by meansofaservomotor(伺伺服服电电动动机机马达马达).Thischangestheoilflowandthusthespeedoftherotorinthehydraulicmotor.Thesafetysystemconsistsof:amainsafetyvalve;twopressurereducingvalves.The slewing winch, which isalmostidenticaltoluffingwinch, is controlled by usingthe same handle as that usedfortheluffingwinch.A small movement of thecontrolhandletotherightorleftgivesrisetooilpressureinthebrakecylinderandreleasesthe brake on the slewingwinch.Movementofthecontrolhandle to the right or left in excess ofthe positions that release the brake starts thecrane moving to the right orleftrespectively.The closed hydraulic systemconsists of an axial pistonpump with variable outputandahydraulicmotormutually connected throughoilpressurelines.The amount of oil flowingthrough the system and thedirectionofflowareregulatedbymeansofaservomotor.Wheninoperation,itisunavoidablethatasmallamountofoilescapesthroughleakage, and in order tocompensatefortheseleaksthesystem is connected to a feedpump.For pumping up, two checkvalvesareused,andabypassvalvelimitsthepressureto17-25bar.The safety system is designedforacertainmaximumpressure, and the workingpressure must therefore belimited.Forthisreasonthereisincluded a main relief valvethatconnectsthepressuresideofthesystemtoitssuctionsideif the permissible pressure isexceeded.A double check valve with acommon spring ensures thatthereliefvalvealwaysoperates,regardless ofwhichoftheoillinesisthepressureside.ReadingmaterialsMooringequipment(系泊，系缆设备系泊，系缆设备)Wincheswithvariousarrangements of barrels arethe usual mooring equipmentusedonboardships.Itusuallyconsistsofadrivingmotor, a reduction gear, awinchbarrelordrumandoneortwowarpends.The winch barrel or drum isused for hauling in(拖拖 ) orletting out(放放) the wires orropes which will fasten theshiptotheshore.The warp end is used whenmovingtheshipusingropesorwiresfastenedtobollards(系系船船柱柱 ) ashore and wrappedaround the warp end of thewinch.The motor drive is passedthroughaspurgeartransmission,aclutch(离离合合器器)and thus to the drum andwarpend.A substantial frame supportstheassemblyandabandbrakeisusedtoholdthedrumwhenrequired.The control arrangements forthedrivemotorpermitforward or reverse rotationtogether with a selection ofspeedsduringoperation.Mooring Winch Mooring winches provide thefacilityfortensioning(拉拉紧紧,使使紧紧 张张 ) the wire up to thestallingcapacityofthewinch,usually1.5timesfullload,thereafter the load is held bythe prime mover brake orbarrel brake when the powerisshutoff. Thewinchcannotpayoutwireunless the brake is overhauledorrecoverwireunless manually operated, thus wiresmaybecomeslack.Automatic mooring winchesprovide the manual controlpreviously described but inaddition incorporate controlfeaturessuchthat,in the automatic setting, thewinchmaybeoverhauledandwireispaidoffthebarrelatapre-determinedmaximumtension;also wire is recovered at alowertensionshouldittendtobecomeslack(松弛松弛).Thusthereisacertainrangeoftension, associated with eachstepofautomaticcontrol,whenthewireisstationary.Itisnotpracticaltoreducethisrangetotheminimumpossibleasthisresultinhunting(振振荡荡，不稳定不稳定)ofthecontrols. It should be noted that theprincipalreasonfor incorporating automatic controls with the features describedistolimittherender(绞绞上上，拖拖)valueofthewinchandavoidbrokenwires;alsotopreventmooringwiresfrombecomingslack.Loadsensingdevicesareusedwithautomaticmooringwinches,e.g.spring-loadgearwheels and torsion barsare widely used with steamandelectricwinches;fluid pressure sensing eithersteamorhydraulicoilpressure, is also used whereappropriate.The majority of automaticmooring winches are spurgearedtoimprovethebackward efficiency of thegeartrain(齿齿 轮轮 系系 )forrendering,thegearingandbearingsbeingtotallyenclosedandlubricatedfromtheoilsump.On larger mooring wincheswhereabarrelbrakeisfitted,it is now common practice todesignthebraketowithstandthe breaking strength(断断裂裂强强度度 或或 负负 荷荷 ) of the mooringwire.Worm geared (蜗蜗 杆杆 传传 动动 的的 )automatic mooring winches areuncommon as the multi-start(多多头头) feature required to improved gear efficiencyreducestheadvantage of worm gear i.e. thehighgearratio.B.Anchorhandlingequipment(抛锚设备抛锚设备)The windlass(锚锚 机机 ) is theusual anchor handling devicewhere one machine may beusedtohandlebothanchors.A more recent development,particularly on larger vessels,is the split(分分离离的的) windlasswhereonemachineisusedforeachanchor.ChainorcablelockerSpurlingpipeCablelifterAnchorThe rotating units of a splitwindlass consist of a cablelifter(锚锚 链链 轮轮 ) with shapedsnug(凸凸起起)togriptheanchorcable,amooringdrumforpayingoutorlettinggoofmooringwiresand a warp end for warpingduties.Each of these unites may beseparatelyengagedordisengagedbymeansofadogclutch(爪爪形形离离合合器器),althoughthewarpendisoftendriveninassociation with the mooringdrum.Aspurgearassemblytransmits the motor drive tothe shaft where the variousdogclutchesenablethepowertake-off.Separate band brakes arefitted to hold the cable lifterand the mooring drum whenthepowerisswitchedoff.Thecablelifterunitismounted so as to raise andlower the cable from thespurlingpipe(锚锚链链管管),whichisatthetopandcenterofthechainorcablelocker(锚链舱锚链舱).Anchor capstans(起起 锚锚 绞绞 盘盘 )are used in some installationswhere the cable lifter rotatesaboutaverticalaxis.Only the cable lifter unit islocated on deck, the drivingmachinery being on the deckbelow.C.Preliminaries(准备工作准备工作)foroperatingthehydraulicdeckmachineryFillingthedeckmachinerywithoilOilspecially made for operation of hydraulic pump, hydraulic motor and hydraulic equipmentshouldbeused.Incasesuchoilisnotavailable,turbineoilofagoodqualitymaybeused.Use of water, light oil, heavyoil,animalorvegetableoilandalso ordinary machine oil isstrictlyprohibited.Leakage of oil or stick of themovingpartsofpumpswillbecaused by less viscosity andexcessive friction losses ornoiseofpumpswillbecausedbyhigherviscosity.When starting up the pump,viscosity of the oil should notexceed 2000cst, but it shallalwaysbeover15cst.After checking up the oil, fillthesystemasfollowing:1.Filltheheadtankwithoilbythehandpump.2. Open the air vent valves(hyd.Pump,hyd.Motor,strainer, oil cooler, controlvalve,piping)3. Close the air vent valvesafter the system is filled upwithoil.Preliminaryoperationofthesystem1.Priortorunningthepump,examine the system carefullyand:a).Ensure that the lever ofcontrol valve is in neutralposition.b).Ensure that all the valvesaresetinnormalposition.2,filltheheadtankwithoilifnecessary.d).Confirmtheoiltemperature above the valuecorrespondingtotheoilviscosityof450cst.In case of the oil viscosityabove450cst,(i)Open the stop valve forwarmingupofpumpunit.(ii) Inch the electric motortwice.(iii)Runtheelectricmotor.(iv)Closethestopvalve.e).Applygearoil.f). Grease up bearing metalandlinkage.2. After satisfying the aboveinstruction,startuptheelectric motor and run thepump,andexpel(放放出出)airinthecircuit.3. Check whether noise orvibration of the hydraulicpumpisnormalornot.