DESIGN AND FABRICATION OF MOTORIZEDDESIGNANDFABRICATIONOFMOTORIZEDSCREWJACKFORAFOURWHEELER

ByMounika.Kandi.Reddy Ch.Priyanka

4thyearMechanical

GokarajuRangarajuInstituteOfEngineeringAndTechnology

INTRODUCTION Powerscrewsareusedtoconvertrotarymotioninto

translatorymotion.

Ascrewjackisanexampleofapowerscrewinwhichasmallforce applied in a horizontal plane is used to raise or lower aforceappliedinahorizontalplaneisusedtoraiseorloweralargeload.

Theprincipleonwhichitworksissimilartothatofaninclinedplane.

FORMSOFTHREADS

TwopopulartypesofthreadsusedforpowerscrewsaresquareandI.S.Ometrictrapezoidal.q p

Thereisaspecialtypeofthreadcalledacmethread.Inacmethread,thethreadangleis29.

Anothertypeofthreadusediscalledbuttressthread.Itcombinestheadvantagesofsquareandtrapezoidalthreads.

TERMINOLOGYOFPOWERSCREW

Pitch

Lead

Nominaldiameter

Corediameter

Helixangle

SELFLOCKINGSCREW

Ascrewwillbeselflockingifthecoefficientoffrictionisequalg qtoorgreaterthanthetangentofthehelixangle.

For self locking screwFor self locking screw, >

tan > tan >

EFFICIENCYEFFICIENCY

EfficiencyofaSquareThreadedScrewy q

=

=

MOTORIZEDSCREWJACK

Themotorizedscrewjackhasbeendevelopedtocatertotheneeds of small and medium automobile garagesneedsofsmallandmediumautomobilegarages.

Inmostofthegaragesthevehiclesareliftedbyusingscrewjack.Thisneedshighmanpowerandskilledlabor.

Themotorizedjackhasbeendesignedinsuchawaythatitcanbeusedtoliftthevehicleverysmoothlywithoutanyimpactforce,therebyincreasingthemechanicaladvantage.

WORKINGPRINCIPLE

Thescrewjackmovesthescrewupward,sothatthevehicleliftsfromground.

Thevehicleisliftedbyusingtheliftingplatformatthetopofthe screw jackthescrewjack.

Theleadacidbatteryisusedtodrivethed.cmotor.

Themotordrawspowersupplyfromthebattery.p pp y y

Thed.cmotorshaftisconnectedtothespurgear.

Theliftingandupliftingisdonebychangingthebatterysupplytothemotor.

PARTSOFMOTORIZEDSCREWJACK

ScrewJack

D.c.motor(permanentmagnet)

Battery

SpurGear

Switch

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.

MECHANICALJACKSScissorJacks

Ascissorjackisadeviceconstructedwithacrosshatchmechanism,muchlikeascissor,toliftupavehicleforrepairorstorage.

It typically works in just a vertical manner Ittypicallyworksinjustaverticalmanner.

Thejackopensandfoldsclosed,applyingpressuretothebottomsupportsalongthecrossedpatterntomovethelift.

Whenclosed,theyhaveadiamondshape.

BOTTLEJACKS

Bottlescrewsmayoperatebyeithery p y

(i)Rotatingthescrewwhenthenutisfixed;or

(ii)Rotatingthenutandpreventingrotationofthescrew.

Bottlejacksmainlyconsistofascrew,anut,thrustbearings,and a body.andabody.

Astationaryplatformisattachedtothetopofthescrew.Thisplatformactsasasupportfortheloadandalsoassistsitinliftingorloweringoftheload.

Thesejacksaresturdierthanthescissorjacksandcanliftheavier loadsheavierloads.

DESIGNOFSCREWJACK

SelectionofMaterials

LoadsandStressesinScrew

ThrustBearings

DesigncalculationstocheckthesafetyofLEADSCREW

Designcalculationstocheckthesafetyofnut

Designcalculationstocheckthebucklingofscrew

OPERATIONALCONSIDERATIONSOFASCREWJACK

Maintainlowsurfacecontact pressurecontactpressure.

Maintain low surface speed.Maintainlowsurfacespeed.

Keepthematingsurfaceswelllubricated.

K th ti f Keepthematingsurfacesclean.

Keepheataway.

D.C.MOTOR(PERMANENTMAGNET)

Anelectricmotorisamachinewhichconvertselectricalenergytomechanicalenergy.

Asimple2poleDCelectricmotorhas6parts

1.Anarmatureorrotor

2.Acommutator

3 B h3.Brushes

4.Anaxle

5 A field magnet5.Afieldmagnet

6.ADCpowersupplyofsomesort

BATTERIES

Inisolatedsystemsawayfromthegrid,batteriesareusedfor storage of excess solar energy which can be convertedforstorageofexcesssolarenergywhichcanbeconvertedintoelectricalenergy.

Tobeeconomicallyattractivethestorageofsolarelectricityrequiresabatterywithaparticularcombinationofproperties:1 Low cost1.Lowcost2.Longlife3.Highreliability4.Highoverallefficiency5.Lowdischarge

6 Minimummaintenance6.Minimummaintenance

Thechemicalequationfortheleadacidcellis

Pb + pbO + 2HSO 2pbSO + 2HO

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.

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.

SWITCH

Aswitchisusedinordertostartorstoptheentireoperationofthescrewjack.Thetypeofswitchthatisusedisknownasaj yptoggleswitch.

Controlcables areusedinordertoconnectthebatterytothemotor and the switchmotorandtheswitch.

Abasefortheentiresetuphasalsobeenused.Themotoris

mountedonaninvertedUshapedsupportframe.

ADVANTAGES

Theloadedlightvehiclescanbeeasilylifted.

Checkingandcleaningareeasy,becausethemainpartsarescrewed.

Handlingiseasy

NoManualpowerrequired.

EasytoRepair.

Replacementofpartsareeasy

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

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.