mech-design and fabrication of motorized screw jack for a four wheeler
TRANSCRIPT
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DESIGN AND FABRICATION OF MOTORIZEDDESIGNANDFABRICATIONOFMOTORIZEDSCREWJACKFORAFOURWHEELER
ByMounika.Kandi.Reddy Ch.Priyanka
4thyearMechanical
GokarajuRangarajuInstituteOfEngineeringAndTechnology
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INTRODUCTION Powerscrewsareusedtoconvertrotarymotioninto
translatorymotion.
Ascrewjackisanexampleofapowerscrewinwhichasmallforce applied in a horizontal plane is used to raise or lower aforceappliedinahorizontalplaneisusedtoraiseorloweralargeload.
Theprincipleonwhichitworksissimilartothatofaninclinedplane.
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FORMSOFTHREADS
TwopopulartypesofthreadsusedforpowerscrewsaresquareandI.S.Ometrictrapezoidal.q p
Thereisaspecialtypeofthreadcalledacmethread.Inacmethread,thethreadangleis29.
Anothertypeofthreadusediscalledbuttressthread.Itcombinestheadvantagesofsquareandtrapezoidalthreads.
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TERMINOLOGYOFPOWERSCREW
Pitch
Lead
Nominaldiameter
Corediameter
Helixangle
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SELFLOCKINGSCREW
Ascrewwillbeselflockingifthecoefficientoffrictionisequalg qtoorgreaterthanthetangentofthehelixangle.
For self locking screwFor self locking screw, >
tan > tan >
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EFFICIENCYEFFICIENCY
EfficiencyofaSquareThreadedScrewy q
=
=
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MOTORIZEDSCREWJACK
Themotorizedscrewjackhasbeendevelopedtocatertotheneeds of small and medium automobile garagesneedsofsmallandmediumautomobilegarages.
Inmostofthegaragesthevehiclesareliftedbyusingscrewjack.Thisneedshighmanpowerandskilledlabor.
Themotorizedjackhasbeendesignedinsuchawaythatitcanbeusedtoliftthevehicleverysmoothlywithoutanyimpactforce,therebyincreasingthemechanicaladvantage.
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WORKINGPRINCIPLE
Thescrewjackmovesthescrewupward,sothatthevehicleliftsfromground.
Thevehicleisliftedbyusingtheliftingplatformatthetopofthe screw jackthescrewjack.
Theleadacidbatteryisusedtodrivethed.cmotor.
Themotordrawspowersupplyfromthebattery.p pp y y
Thed.cmotorshaftisconnectedtothespurgear.
Theliftingandupliftingisdonebychangingthebatterysupplytothemotor.
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PARTSOFMOTORIZEDSCREWJACK
ScrewJack
D.c.motor(permanentmagnet)
Battery
SpurGear
Switch
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SCREWJACK
Ascrewjackisaportabledeviceconsistingofascrewh i d t i l th l dmechanismusedtoraiseorlowertheload.
Theprincipleonwhichthescrewjackworksissimilartothatofaninclinedplane.p
Typicallythisisusedtochangeatirealthoughothermaintenanceissometimesperformed.
Therearemainlytwotypesofjacks
(i)Hydraulic
(ii) M h i l(ii)Mechanical
Ahydraulicjackconsistsofacylinderandpistonmechanism.Themovementofthepistonrodisusedtoraiseorlowerthepload.
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MECHANICALJACKSScissorJacks
Ascissorjackisadeviceconstructedwithacrosshatchmechanism,muchlikeascissor,toliftupavehicleforrepairorstorage.
It typically works in just a vertical manner Ittypicallyworksinjustaverticalmanner.
Thejackopensandfoldsclosed,applyingpressuretothebottomsupportsalongthecrossedpatterntomovethelift.
Whenclosed,theyhaveadiamondshape.
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BOTTLEJACKS
Bottlescrewsmayoperatebyeithery p y
(i)Rotatingthescrewwhenthenutisfixed;or
(ii)Rotatingthenutandpreventingrotationofthescrew.
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Bottlejacksmainlyconsistofascrew,anut,thrustbearings,and a body.andabody.
Astationaryplatformisattachedtothetopofthescrew.Thisplatformactsasasupportfortheloadandalsoassistsitinliftingorloweringoftheload.
Thesejacksaresturdierthanthescissorjacksandcanliftheavier loadsheavierloads.
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DESIGNOFSCREWJACK
SelectionofMaterials
LoadsandStressesinScrew
ThrustBearings
DesigncalculationstocheckthesafetyofLEADSCREW
Designcalculationstocheckthesafetyofnut
Designcalculationstocheckthebucklingofscrew
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OPERATIONALCONSIDERATIONSOFASCREWJACK
Maintainlowsurfacecontact pressurecontactpressure.
Maintain low surface speed.Maintainlowsurfacespeed.
Keepthematingsurfaceswelllubricated.
K th ti f Keepthematingsurfacesclean.
Keepheataway.
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D.C.MOTOR(PERMANENTMAGNET)
Anelectricmotorisamachinewhichconvertselectricalenergytomechanicalenergy.
Asimple2poleDCelectricmotorhas6parts
1.Anarmatureorrotor
2.Acommutator
3 B h3.Brushes
4.Anaxle
5 A field magnet5.Afieldmagnet
6.ADCpowersupplyofsomesort
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BATTERIES
Inisolatedsystemsawayfromthegrid,batteriesareusedfor storage of excess solar energy which can be convertedforstorageofexcesssolarenergywhichcanbeconvertedintoelectricalenergy.
Tobeeconomicallyattractivethestorageofsolarelectricityrequiresabatterywithaparticularcombinationofproperties:1 Low cost1.Lowcost2.Longlife3.Highreliability4.Highoverallefficiency5.Lowdischarge
6 Minimummaintenance6.Minimummaintenance
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Thechemicalequationfortheleadacidcellis
Pb + pbO + 2HSO 2pbSO + 2HO
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SPURGEAR
Thespurgears,whicharedesignedtotransmitmotionandp g , gpowerbetweenparallelshafts,arethemosteconomicalgearsinthepowertransmissionindustry.
Designconsiderationsforageardrive
In the design of a gear drive the following data is usually Inthedesignofageardrive,thefollowingdataisusuallygiven:
1.Thepowertobetransmitted,
2.Thespeedofthedrivinggear,
3.Thespeedofthedrivengearorthevelocityratio,and
4.Thecentredistance.
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Thefollowingrequirementsmustbemetinthedesignofageardrive:
(a)Thegearteethshouldhavesufficientstrengthsothattheywill not fail under static loading or dynamic loading duringwillnotfailunderstaticloadingordynamicloadingduringnormalrunningconditions.
(b)Thegearteethshouldhavewearcharacteristicssothattherelifeissatisfactory.
(c)Theuseofspaceandmaterialshouldbeeconomical.
(d) Th li t f th d d fl ti f th h ft t(d)Thealignmentofthegearsanddeflectionsoftheshaftsmustbeconsideredbecausetheyaffecttheperformanceofthegears
(e)Thelubricationofthegearsmustbesatisfactory.
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SWITCH
Aswitchisusedinordertostartorstoptheentireoperationofthescrewjack.Thetypeofswitchthatisusedisknownasaj yptoggleswitch.
Controlcables areusedinordertoconnectthebatterytothemotor and the switchmotorandtheswitch.
Abasefortheentiresetuphasalsobeenused.Themotoris
mountedonaninvertedUshapedsupportframe.
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ADVANTAGES
Theloadedlightvehiclescanbeeasilylifted.
Checkingandcleaningareeasy,becausethemainpartsarescrewed.
Handlingiseasy
NoManualpowerrequired.
EasytoRepair.
Replacementofpartsareeasy
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DISADVANTAGES Costoftheequipmentishighwhencomparedtoordinary
handjack.
Care must be taken for the handling the equipment such as Caremustbetakenforthehandlingtheequipmentsuchasproperwiringconnection,batterychargingcheckup,etc.
APPLICATIONS
Itisusefulinautogarages.
Thismotorizedscrewjackisusedforliftingvehicles.Thusitcanbeusefulforthefollowingtypesofvehiclesinfuture;Maruti Ambassador FiatMaruti,Ambassador,Fiat,
Mahindra
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CONCLUSION
ScrewJacksaretheidealproducttopush,pull,lift,lowerandpositionloadsofanythingfromacoupleofkilogramstop y g p ghundredsoftonnes.
Theneedhaslongexistedforanimprovedportablejackfort ti hi lautomotivevehicles.
Themainrequirementofamotorizedscrewjackisstability.Itshouldbeeasilycontrollablebyaswitchsothatjackingcany y j gbedonefromapositionofsafety.Itshouldalsobeeasilymovableeithertoapositionunderneaththeaxleofthevehicle or some other reinforced support surface designed tovehicleorsomeotherreinforcedsupportsurfacedesignedtobeengagedbyajack.
Thus,theproducthasbeendevelopedconsideringalltheaboverequirements.