Wheels Assembly

The wheel assembly consists of the hub, disc or spokes, rim, tyre & tube.Wheels is the important part of the vehicle. The vehicle can’t move on the road without wheels. “ The wheels are legs of the vehicle carry it to far off distance. The support of the whole weight of the vehicle & convert rotary motion into longitudinal one".

1. ER. PEEYUSH CHAUHAN
ASSISTANT PROFESSOR
DEPARTMENT OF MECHANICAL ENGINEERING

3. “Thewheelassemblyconsistsofthehub,discorspokes,rim,
tyre&tube..”
Wheelsistheimportantpartofthevehicle.Thevehiclecan’t
moveontheroadwithoutwheels.“Thewheelsarelegsofthe
vehiclecarryittofaroffdistance.Thesupportofthewhole
weightofthevehicle&convertrotarymotioninto
longitudinalone.”
Thewheelalsoresistssideforcecreatedbyturningalso
absorbtheroadshocks.

4. Inanautomobileessentialrequirementofwheelsareas
follows–
1.Strongenoughtotaketheweightofvehicle.
2.Flexibletoabsorbtheroadshocks.
3.Perfectlybalancedstaticallyaswellasdynamically.
4.Abletogriptheroadsurface.
5.Mountedorremoveeasily.
6.Nottooexpensive.
7.Lightestpossiblesothattheunsprungweightisleast.

5. Theautomobilewheelsaregenerallythreetypes:-
(i)Pressedsteeldiscwheels.
(ii)Wirewheels.
(iii)Lightalloycastingwheels.
(i)Pressedsteeldiscwheels:-itsconsistsofasteelrim&a
pressedsteeldisc.Therimisrolledsection,sometimeriveted
butusuallyweldedtotheflangeofthedisc.Thediscperform
thefunctionofspokes.Thewheelassemblyboltedtothe
brakedrum.

9. ThePressedsteelwheelshavethefollowingadvantages:-
1.Simple&robustinconstruction.
2.Easytoproducedinlargenumberatlowcost.
3.Requirednegligiblerequirement.
4.Easetocleaning.
2.WireWheels:-
Wirewheels,wire-spokewheels,tension-spokewheels,
or"suspension"wheelsarewheelswhoserimsconnectto
theirhubsbywirespokes
Wirewheelsareusedonmostbicyclesandarestillusedon
manymotorcycles.Theywereinventedbyaeronautical
engineerGeorgeCayleyin1808.Thefirstpatentforwire
wheelswasissuedtoTheodoreJonesofLondon,Englandon
October11,1826.

11. Thewirewheelconsistsofseparatehubconnectedtotherim
withanumberofspokesorwires.Theheadedinnerendofthe
spokesfitinthehubholes&thethreadedouterendfitinthe
rimholes,wheremushroom-headedtubularnutsarescrewed
throughtherimholestotightenthehub.
3.Lightalloycastingwheels:-
Thelightalloycastorforgedwheelsisthemostrecenttype,
whoseuseineverincreasingbothroad&sportscars.Its
generallyuselightalloy(aluminum&magnesiumalloys)
whichmakesitpossibletousewiderrims,lowaspectratio,
thusimprovinggoodadhesion,especiallyoncorners.

14. Thelightalloycastingwheelshavefollowingadvantages:-
1.Lightinweight.
2.Lightalloybeinggoodheatconductorsdissipateheat
producedbytyres&brakemoreefficientlythansteel.
3.Heaviersectioncanbeusedwhichimprovethewheel
stiffness&betterstressdistributionisobtained.

16. “Atyreisacushionprovidedwithanautomobilewheel.Its
consistsofmainlytheoutercoveri.e.,thetyreproper&tube
inside.”
Thetyre-tubeassemblymountedoverthewheelrim.Theair
insidethetubecarriestheentireload&providethecushion.
Thetyresarefinalcontactbetweentheroad&thevehicle.
Theytakealltheloadofthevehicle.Theyareflexible&
absorbmostoftheshockswhenacarmovingonroughroads.
Thesurfaceofthetyrehascertainpatternswhichenableitto
griptheroad&providegoodtraction.

17. ATyreperformthefollowingfunctions:-
1.Supporttheloadofthevehicle.
2.Providecushionagainstshocks.
3.Transmitsdriving&brakingforcetotheroad.
4.Providescorneringpowerforsmoothsteering.

18. SomeimportantrequirementsofgoodTyreare:-
1.Tobestrongenoughtocarryload&resistsdamage.
2.Toprovideacomfortableridetothemotorists.
3.Toprovidegoodroadgripfortraction,cornering,
acceleration&braking.
4.Toprovidequiterunning.
5.Tohavealonglife.
6.Tobeeconomical.
7.Tobeflexibletocushionallshocks&impactsatleast
partly.

19. TYRE CONSTRUCTION
Thelowerportiononbothsideshasasetofsteelwire
called“beadwire”.Thesewireshousetyresnuglyinrim
&alsodon’tallowitcomeoutevenintheeventoftyre
burst.
Thebeadwirearesurroundedbythe“beadcore&plies
ofcanvass”.Thesedays,insteadofcanvassRayonor
Nylonisusedtogivemorestrength.
Onthetyresidewallsasonpliesrubbersvulcanized
whichprotectsthepliesfrominjuriesduetopebbles.

24. Thetopportioniscalled“tread”asitcomecontactwith
theroad&issubjectedtowear.Assuchitsmadethicker.
The“breakers”arerubbercoveredcordssimilartoplies.
Thejobofbreakeristodistributesroadshocks&prevents
separationoftreadfromtyre.
The“cushion”issoftheatresistancerubber,which
absorbsroadshocks&alsobindplies&breakertogether.
The“cordplies”givestrengthtoresistsinternal
pressuretosupportload&roadshocks.

25. Nylon
1. Based on carcass Materials Steel Belted
Polyester Belted
Rayon's
Cross Ply
2. Based on the Construction Radial
Belted Bias
Conventional tubed Tyre
3. Based on the tube Tubeless Tyre

26. Light Load tyres
4. Based on the load Heavy Load tyres
Other types tyres
Summer
5. Based on the Session Winter
All Seasons
Lug
6. Based on pattern designRib
Semi-Lug

27. BASED ON TUBE
1.ConventionalTubedTyre:-Intheconventionaltubedtyre
outerportionofthetyrewhichrollsontheroadmadeof
syntheticrubber&itscalled“tread”.
Thetyreenclosedatubeinwhichairisforcedtohigh
pressureasacushioningmedium.Avalvestemisattachedto
thetubeforinflatingordeflectingthesame.
Inordertopreventthetyrefrombeingthrownofftherim,the
plies(formedfromrayoncords)areattachedtotworingsof
hightensionsteelwires.Theseringsaremadetofitsnugly
againstthewheelrimtherebyanchoringthetyretotherim.
Theseringsarecalled“Beads”.

30. 2.TubelessTyre:-Thistypeoftyredoesnotenclosedatube,
insteadtheairunderpressureisfilledinthetyreitselffor
whichpurposeanonreturnvalveisfittedtotherim.
Theinnerconstructionofthetyreisalmostsameasthatof
tubetyre,expectthatitslinedwithaspecialairretainingliner
madeupofhalogenatedbutylrubber(e.g.Chlorobutyleor
bromobutyl)forbetterairpermeabilitytogetherwithheat&
weatherresistance.
Atubelesstyreretainsairforalongerperiodevenafterbeing
puncturedbynails,providingthenailsremainsinthetyre.
Also,anyholeinthetubelesstyrecanberepairedsimplyby
rubberplugging.

33. BASED ON THE LOAD
1.Light–mediumdutytyres:-
Light-dutytiresforpassengervehiclescarryloadsintherange
of550to1,100pounds(250to500kg)onthedrivewheel.
Light-to-mediumdutytrucksandvanscarryloadsintherange
of1,100to3,300pounds(500to1,500kg)onthedrive
wheel.
1.Winter—Snowtiresaredesignedforuseonsnowandice.
Theyhaveatreaddesignwithlargergapsthanthoseon
summertires,increasingtractiononsnowandice.
2.All-season—RelatedtosnowtiresarethosewithanM+S
rating,whichdenotesan"all-season"capabilityquieteron
clearroads,butlesscapableonsnoworicethanawintertire.

34. (a)All-terrain—All-terraintiresaredesignedtohave
adequatetractionoffroad,yethavebenignhandlingand
noisecharacteristicsforhighwaydriving.Suchtiresarerated
betteronsnowandrainthanstreettiresand"good"onice,
rockandsand.
(b)Mud-terrain—Mud-terraintireshaveadeeper,more
opentreadforgoodgripinmud,thanall-terraintires,but
performlesswellonpavement.
(c)High-performance—High-performancetiresarerated
forspeedsupto168milesperhour(270km/h)andultra-
high-performancetiresareratedforspeedsupto186miles
perhour(299km/h),buthaveharsherridecharacteristicsand
durability.

35. Othertypesoflight-dutyautomotivetiresinclude
1.Run-flattires
2.Racecartires.
1.Run-flattires—Run-flattiresobviatetheneedforaspare
tire,becausetheycanbetravelledonatareducedspeedin
theeventofapuncture,usingastiffsidewalltoprevent
damagetothetirerim.Vehicleswithoutrun-flattiresrelyon
asparetire,whichmaybeacompacttire,toreplacea
damagedtire.
2.Race-cartires—Racecartirescomeinthreemain
categories,DOT(street-legal),slick,andrain.Racecartires
aredesignedtomaximizecorneringandaccelerationfriction
attheexpenseoflongevity
.

36. 2.Heavydutytyres:-
Heavydutytiresforlargetrucksandbusescomeinavariety
ofprofilesandcarryloadsintherangeof4,000to5,500
pounds(1,800to2,500kg)onthedrivewheel.Theseare
typicallybemountedintandemonthedriveaxle.
1.Trucktires—Trucktirescomeinavarietyofprofilesthat
include"lowprofile"withasectionheightthatis70to45%
ofthetreadwidth,"wide-base"forheavyvehicles,anda
"super-single"tirethathasthesametotalcontactpressureas
adual-mountedtirecombination.
2.Offroad—Off-roadtiresareusedonconstruction
vehicles,agriculturalandforestryequipmentandother
applicationsthattakeplaceonsoftterrain.

37. 3. Other types tyres:-
1.Aircraft—Mostaircrafttiresaredesignedforlandingon
pavedsurfacesandrelyontheirlandinggeartoabsorbthe
shockoflanding.Example-Boeing777.
2.Bicycle—Bicycletiresmaybedesignedforridingonroads
oroverunimprovedterrainandmaybemountedon
vehicleswithmorethantwowheels.Therearethreemain
types:clincher,wiredandtubular.
3.Industrial—Industrialtiressupportsuchvehiclesas
forklifts,tractors,excavators,roadrollers,andbucket
loaders.Thoseusedonsmoothsurfaceshaveasmoothtread,
whereasthoseusedonsoftsurfacestypicallyhavelarge
treadfeatures.

38. 4.Motorcycle—Motorcycletireprovidetraction,resisting
wear,absorbingsurfaceirregularities,andallow
themotorcycletoturnviacountersteering.Thetwotires
contactwiththegroundaffectsafety,braking,fueleconomy,
noise,andridercomfort.

39. BASED ON THE CONSTRUCTION
1.CrossPlyConstructiontype:-inthistypeoftyre
constructiontheplycordarewovenatanangle30
0
to40
0
to
thetyreaxis.Therearetwolayerwhichruninopposite
directions.
Thesetypeoftyrehavebetterwear&roadholding
characteristics.Thesetypeoftyrefittedonfrontwheelonly.
Thesetypeoftyreareeconomical.
2.RadialPlyConstructiontype:-thesetyrepiesrunning
beadtobeadacrosstothecrownatrightangletotherotation.
Onthesidewallthedirectionofthesepliesareradial.

41. Theanglebetweenthecordsvariesfrom18
0
to22
0
.The
numberoflayerofdependinguponthematerialsused.
3.BeltedBiasPlyConstructiontype:-Thesetypeoftyre
constructioniscombinationofCrossply&Radialplytyre.

42. BASED ON THE THREAD PATTERN
1.RibPattern-Thepatternhasseveralzig-zaggroovesthat
runalongthecircumferenceoftyre.Theribpatternis
recommendedforuseinbothpassenger&commercial
vehicles&whenthedriveistobeathighspeedsason
pavedsurface.
WithRibpattern:-
1.Tyrerollingresistancebecomeless
2.Noiselevelgetsreduced
3.Inferiortraction
4.Greaterresistancetosideslipping

43. 2.LugPattern-Thepatternhasgroovesthatrunroughlyat
rightanglestothetyrecircumference.Thelugspatternis
usedfortruckswhendrivingisonunpavedsurface.
WithLugpattern:-
1.Tractionisgood.
2.Rollingresistanceishigh.
3.Resistancetotendencyforsideslipisless.
4.Unevenwearoftreadinlugsarea.

45. 3.Semi-LugPattern-Thepatterndesignisacombinationof
Rib&Lugspattern.Thispatternprovidethestabledriving
performancebothonpavedsurface&unpavedsurface.
WithSemi-Lugpattern:-
1.Theribpatternrunningalongthecenteroftyre
minimizethesideslipoftyrethatimpartsstabilityto
vehicle.
2.Thedriving&brakeperformanceisimprovedbylug
patternontheedge..
3.Unevenwearoftreadinlugsareaoftyre.

46. Thetreadpatternmayfurtherdesignas-
1.Symmetricthreadpattern-wherebothhalvesofthe
threadfaceareexactlysimilar.
2.Asymmetricthreadpattern-wherebothhalvesofthe
threadfacearedissimilar.
3.Directionalthreadpattern-inwhichdesigntobe
installedinparticulardirection.

48. TYRE MATERIALS
The various materials used for construction of tyres as
follows:-
-Rubber used in tyre is a blend of the natural & synthetics
rubbers( Styrene butadiene rubber & poly butadiene) with
various chemicals (carbon, sulphur etc.) which improve wear
resistance, reduced friction & hysteresis.
-Bronze plated high tensile steel is used for beads.
-The Rayon, terylene, glass fiber or steel are used for Cords.
-The steel is used in radial tyre belt & belted-bias tyre.
-The pliesare made of nylon, polyester & fiber glass.

49. TYRE SPECIFICATIONS/ MARKING
The size of the tyre has following specifications:-
P205/65R1594H
1. The first letter designates the type of tyre-
P-Passenger
LT-Light Transport (Truck)
T-Temporary i.e. spare
2. The next figure indicates the section width of inflated tyre
in mm.
3. The figure after slash/ indicates the aspect ratio(H/W) of
tyre as a percentage.
Where H= Section Height & W= Section Width

50. 4.Thenextletterdesignatesthetyreconstruction
R-Radialtyre
B-Beltedbias-plytyre
D-Biasplytyre
5.Thenextfigureindicatesthediameterofwheelrimininch
onwhichtyreistofit.
6.Thenextfigureindicatesthespeedratinginkm/hr.

54. WHEEL OFFSET
Offsetreferstodistancebetweenthehubmountingsurface&
wheel’scenterline.Thewheeloffsetarethreetypes.
1.Zerowheeloffsetiswhenthehubmountingsurfaceisin
linewiththecenterlineofthewheel.
2.Positivewheeloffsetiswhenthehubmountingsurfaceis
infront(moretowardthestreetside)ofthecenterlineofthe
wheel.Mostwheelsonfront-wheeldrivecarsandnewer
rear-drivevehicleshavepositiveoffset.
3.Negativeoffsetiswhenthehubmountingsurfaceisbehind
thewheelcenterline.“Deepdish”wheelsaretypicallya
negativeoffset.

56. TYRE INFLATION PRESSURE
Foreverytyre,inflationpressuresarespecifiedby
manufacturer.Theserecommendedpressureshouldbestrictly
adheredtosincetheyhelptomeettherequirementsof:-
1.Goodperformance
2.Heatcontrol
3.Bettervehiclecontrol
4.Comfort
5.Treadkilometer
Incorrectpressureleadto
Overheating,unsafesteering&Rapidtyrewear.

57. CAUSE OF TYRE WEAR
Followingcauseoftyrewearare:-
1.Incorrectinflection.
2.Unequaltyres.
3.Bleedingofairintyre.
4.Incorrectrotationoftyres.
5.Misalignment.
6.Outofbalancewheel.
7.Wrongloading.
8.Overloading.
9.Toe-out.
10.Carelessdriving.
11.Excessivebraking.

58. FACTOR AFFECTING TYRE LIFE
Followingmainfactorsaffectingtyrelifeare:-
1.Incorrectinflection.
2.Maintenanceofvehicle.
3.Mannerofdriving.
4.Miscellaneousfactors:-.
a.Heat.
b.Roadconditions.
c.Seasons.
d.Positioninwhichtyreisfitted.