Hydraulics IOE PPT

BasicsofHydraulics MajorapplicationsinEarthMovingEquipment MajorComponentsofHydraulicSystem HydraulicSystemDesign

BasicsofHydraulics yLIQUIDSHAVENOSHAPEOFTHEIROWN.Theyacquiretheshapeofanycontainer.Be causeofthis,oilinahydraulicsystem Theyacquiretheshapeofanycontainer Becauseofthis oilinahydraulicsystem willflowinanydirectionandintoapassageofanysizeorshape.

LIQUIDSTRANSMITAPPLIEDPRESSUREINALL Q DIRECTIONS. LIQUIDSAREPRACTICALLYINCOMPRESSIBLE. LIQUIDSAREPRACTICALLYINCOMPRESSIBLE LIQUIDSPROVIDEGREATINCREASESINWORK FORCE. FORCE Thisprinciplehelpsyoutostopalargemachinebypressingabrakepedal.

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HOWAHYDRAULICSYSTEMWORKS HOW A HYDRAULIC SYSTEM WORKS1. 1 2. 3. 4 4. 5. 6. 6 7. 8. 9. 10. 0.1/2/2010

ThePUMP whichmovestheoil. whichmovestheoil TheCYLINDER whichusesthemovingoiltodowork. CHECKVALVES toholdtheoiltheoilflow. h ld h l h l fl ARESERVOIR (anditsAncillaries)tostoretheoil. ( ) TheCONTROLVALVE directstheoilflow. TheRELIEFVALVE protectsthesystemfromhigh pressures. Gaugesshowflowandpressureatvariouspoints. G h fl d i i Accumulator (iffitted)smoothenstheperformance. Filterstoseparatethecontamination. Primemovertodrivethepump. e ove to d ve t e pu p.Satya Narayan Shah 3

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Driveunit Drive unitHydraulicsystemsaredrivenbymotors(electrical motors,combustionengines). Electricalmotorsgenerallyprovidethe mechanicalpowerforthepumpinstationary hydraulics Combustionenginesaregenerallyusedinmobile hydraulics

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ADVANTAGESFLEXIBILITYUnlikethemechanicalmethodofpowertransmissionwhere therelativepositionsoftheengineandworksitemustremainrelatively constantwiththeflexibilityofhydrauliclines,powercanbemovedtoalmost t t ithth fl ibilit fh d li li b dt l t anylocation. MULTIPLICATIONOFFORCEsmallforcescanbeusedtomovelarge f g loads. SIMPLICITYThehydraulicsystemhasfewermovingparts,fewerpointsof wear.Anditlubricatesitself. wear Anditlubri catesitself COMPACTNESSThehydraulicsystemcanhandlemorehorsepowerforits sizethaneitheroftheothersystems. ECONOMYThisisthenaturalresultofthesimplicityandcompactness whichproviderelativelylowcostforthepowertransmitted.Also,powerand frictionallossesarecomparativelysmall. frictionallossesarecomparativelysmall SAFETYfewermovingpartssuchasgears,chains,beltandelectrical contactsthaninothersystems.Overloadscanbemoreeasilycontrolledby usingreliefvalvesthanispossiblewiththeoverloaddevicesontheother l f l h bl h h l dd h h systems.

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DISADVANTAGESEFFICIENCYWhiletheefficiencyofthehydraulic systemismuchbetterthantheelectricalsystem,itis systemismuchbetterthantheelectricalsystem itis lowerthanforthemechanicaltransmissionofpower. NEEDFORCLEANLINESSHydraulicsystemscanbe damagedbyrust,corrosion,dirt,heatandbreakdown g y , , , offluids.Cleanlinessandpropermaintenancearemore criticalinthehydraulicsystemthanintheother methodsoftransmission. FIREHAZARD Duetoneglegence. FIREHAZARD D l

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APPLICATIONS1/2/2010 Satya Narayan Shah 8

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MajorComponentsofHydraulicSystem j p y yReservoirTank Filters Filt

Pumps ValvesCheckValves DirectionalValves ReliefValves R li fV l

Hydraulicaccumulators Cylinders/Motors

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Hydraulicreservoir y

Thereservoirinahydraulicsystemfulfilsseveral tasks.Itactsasanintakeandstoragereservoirforthe hydraulicfluidrequiredforoperationofthe system; Itdissipatesheat; Itseparatesair,waterandsolidmaterials; Itsupportsabuiltinorbuiltonpumpanddrive I b il i b il dd i motorandotherhydrauliccomponents,suchas valves,accumulators,etc. l l t t

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Hydraulicreservoir H d li iThereservoirconsistsofReservoirbody Intakeandreturnlines Baffleandseparatingplate B ffl d ti l t Ventilationandexhaust Magneticplug

ThesizeofthereservoirdependsonPumpdelivery p y Theheatresultingfromoperation Thevolumeofliquid Theplaceofapplication Thecirculationtime Thesizeofthereservoirisnotclassifiedbyitsphysical Th i fth i i t l ifi db it h i l dimensionsbutitsliquidcapacity Reservoirsize(litres)=pump(litres/min)x3 ( ) p p( / ) 31/2/2010 Satya Narayan Shah 19

ReservoirReturn Connection Filler Breather with filter

Volume of Reservoir 2 - 3 times delivery of pump in 1 minute

Pump

Return line

Access panel

Level indicator

Suction line Strainer Baffles1/2/2010 Satya Narayan Shah 20

Drain Plug

ReservoirAccessoriesHydraulic filterThe task of the filter is to reduce the contamination in the system to an p protect the various components from p acceptable level in order to p excessive wear.

Filler cap (breather cap)Itshouldbeairtightwhenclosed,butmaycontaintheairventwhich I h ldb i i h h l d b i h i hi h filtersairenteringthereservoirtoprovideagravitypushforproperoil flow.

Oil level gaugeIt shows the level of oil in the reservoir without having to open the reservoir.

Intake filterIt is usually a screen that is attached to the suction pipe to filter the hydraulic oil.

Drain plugItallowsalloiltobedrainedfromthereservoir. Somedrainplugsaremagnetictohelpremovemetalchipsfromthe oil.

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ReservoirAccessoriesBaffleplateg g Itislocatedlengthwisethroughthecentreofthetank andis2/3theheightoftheoillevel. Itisusedtoseparatetheoutlettopumpfromthereturn line.Thisensuresacircuitousflowinsteadofthesame li Thi i it fl i t d fth fluidbeingrecirculated. Thebafflepreventslocalturbulenceinthetank,allows Thebafflepreventslocalturbulenceinthetank allows foreignmaterialtosettle,getridofentrappedairand increasesheatdissipation.

SuctionandreturnlinesTheyaredesignedtoenterthereservoiratpointswhere airturbulenceareleast. Theycanenterthereservoiratthetoporatthesides,but theirendsshouldbenearthebottomofthetank. theirendsshouldbenearthebottomofthetank Ifthereturnlineisabovetheoillevel,thereturningoil canfoamanddrawinair.1/2/2010 Satya Narayan Shah 22

Suctionandreturnlines S ti d t liSuction line Return line

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ReservoirAccessoriesHydraulic filters Thetaskofthefilteristoreducethecontamination inthesystemtoanacceptablelevelinorderto protectthevariouscomponentsfromexcessivewear. Coolers Inhydraulicsystems,frictioncausesenergylosses whenthehydraulicfluidflowsthroughthelinesand components. Thiscausesthehydraulicfluidtoheatup. Toacertainextent,thisheatisgivenofftothe environmentviatheoilreservoir,linesandother components Thefollowingcoolingdevicesareavailable: Aircooler:differenceintemperatureofupto25C p p 5 possible. Watercooler:differenceintemperatureofupto35c p possible. Oilcoolingbymeansofairfancooler:whenlarge quantitiesofheatmustbedissipated.

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ReservoirAccessoriesHeatersHeatingelementsorflowpreheatersare usedforheatingandpreheatinghydraulic fluid. fluid Heatersareoftenrequiredtoensurethat optimumoperatingtemperatureisquickly attained. Thisistoensurethatoncethesystemis Thi i t th t th t i startedup,thehydraulicfluidquickly reachestheoptimumviscosity. reachestheoptimum iscosit Iftheviscosityistoohigh,theincreased frictionandcavitationsleadtogreater f i i d i i l d wear.1/2/2010 Satya Narayan Shah 25

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HydraulicPumps Hydraulic PumpsThepumpbasicallyperformstwofunctions:Itcreatesapartialvacuumatthepumpinletport.The vacuumenablestheatmosphericpressuretoforcefluidfrom thereservoirintothepump. thereservoirintothepump Themechanicalactionofthepumptrapsthisfluidwithin thepumpcavities,transportsitthroughthepump,and p p , p g p p, forcesitintothehydraulicsystem.

Itisoftenassumedthatpumpscreatepressure,butthe solepurposeofpumpsistocreateflow. Pressureiscreatedbyresistancetoflow. Apumpisamechanismdesignedtoproducetheflow necessaryforthedevelopmentofpressure. Itcannotitselfproducepressure,sinceitcannotprovide resistancetoitsownflow.1/2/2010 Satya Narayan Shah 27

Hydraulicpumps y p pyp y p p Threebasictypesofhydraulicpumpcanbe distinguishedonthebasisofthedisplacement volume: ConstantpumpsFixeddisplacementvolume Fi ddi l t l

AdjustablepumpsAdjustabledisplacementvolume

VariablecapacitypumpsRegulationofpressure,flowrate.

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HYDRAULIC PUMP FAMILY U C UHYDRAULIC PUMPSGEAR VANE PISTON

FIXED

VARIABLE

EXTERNAL

INTERNAL

FIXED

VARIABLE

AXIAL BENTAXIS

AXIAL BENTAXIS RADIAL

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Hydraulicpumps y p pPumpratingRatedbytheamountoffluidthatcanbedisplacedforeach revolutionofthepumpshaft Specifiedincubicinchesorcubiccentimeterperrevolution

Displacementisdefinedasthevolumeofoilmovedor displacedduringeachcycleofapump. Therearetwoformsofdisplacement: Nonpositivedisplacement p p Positivedisplacement

PositivedisplacementpumpDeliverstothesystemaspecificamountoffluidperstroke, revolutionorcycle1/2/2010 Satya Narayan Shah 30

HydraulicpumpsBesides being positive displacement pumps, they are also categorized as either:

Fixed displacement pumps Variable Variable displacement pumpsFixed displacem