All About Wheel

7/30/2019 All About Wheel

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WheelFrom Wikipedia, the free encyclopedia

For other uses of the term, seeWheel (disambiguation)andWheels (disambiguation).

Look upwheelin Wiktionary,

the free dictionary.

Three wheels on an antiquetricycle
http://en.wikipedia.org/wiki/Wheel_(disambiguation)http://en.wikipedia.org/wiki/Wheel_(disambiguation)http://en.wikipedia.org/wiki/Wheel_(disambiguation)http://en.wikipedia.org/wiki/Wheels_(disambiguation)http://en.wikipedia.org/wiki/Wheels_(disambiguation)http://en.wiktionary.org/wiki/wheelhttp://en.wiktionary.org/wiki/wheelhttp://en.wiktionary.org/wiki/wheelhttp://en.wikipedia.org/wiki/Tricyclehttp://en.wikipedia.org/wiki/Tricyclehttp://en.wikipedia.org/wiki/File:TricycleAntique.jpghttp://en.wikipedia.org/wiki/File:TricycleAntique.jpghttp://en.wikipedia.org/wiki/Wheel_(disambiguation)http://en.wikipedia.org/wiki/Wheels_(disambiguation)http://en.wiktionary.org/wiki/wheelhttp://en.wikipedia.org/wiki/Tricycle


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A wheel is a circular component that is intended to rotate on an axialbearing. The wheel is one of the

main components of the wheel and axlewhich is one of thesix simple machines. Wheels, in

conjunction with axles, allow heavy objects to be moved easily facilitating movement or transportation

while supporting a load, or performing labor in machines. Wheels are also used for other purposes,

such as aship's wheel, steering wheel,potter's wheelandflywheel.

Common examples are found intransport applications. A wheel greatly reduces frictionby facilitating

motion by rollingtogether with the use ofaxles. In order for wheels to rotate, amoment needs to be

applied to the wheel about its axis, either by way of gravity, or by the application of another external

force ortorque.

Contents

[hide]

1 Etymology

2 History

o 2.1 Timeline

3 Mechanics and function

4 Construction

o 4.1 Rim

o 4.2 Hub

o 4.3 Spokes

4.3.1 Wire

o 4.4 Tire

5 Alternatives

6 In semiotics

7 Gallery

8 See also

9 References

10 External links

[edit]Etymology

The English word wheelcomes from the Old Englishword hweol, hweogol, fromProto-

Germanic*hwehwlan, *hwegwlan, from Proto-Indo-European *kwekwlo-,[1]an extended form of the

root *kwel- "to revolve, move around". Cognates within Indo-European include Greek kklos,

"wheel", Sanskritchakra,Old Church Slavonickolo, all meaning "circle" or "wheel", [2]

The Latin wordrota is from the Proto-Indo-European *rot-, the extended o-grade form of the

root *ret- meaning "to roll, revolve".[3]

[edit]History
http://en.wikipedia.org/wiki/Bearing_(mechanical)http://en.wikipedia.org/wiki/Bearing_(mechanical)http://en.wikipedia.org/wiki/Bearing_(mechanical)http://en.wikipedia.org/wiki/Wheel_and_axlehttp://en.wikipedia.org/wiki/Wheel_and_axlehttp://en.wikipedia.org/wiki/Simple_machinehttp://en.wikipedia.org/wiki/Simple_machinehttp://en.wikipedia.org/wiki/Simple_machinehttp://en.wikipedia.org/wiki/Ship's_wheelhttp://en.wikipedia.org/wiki/Ship's_wheelhttp://en.wikipedia.org/wiki/Steering_wheelhttp://en.wikipedia.org/wiki/Steering_wheelhttp://en.wikipedia.org/wiki/Potter's_wheelhttp://en.wikipedia.org/wiki/Potter's_wheelhttp://en.wikipedia.org/wiki/Flywheelhttp://en.wikipedia.org/wiki/Flywheelhttp://en.wikipedia.org/wiki/Transporthttp://en.wikipedia.org/wiki/Transporthttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Rollinghttp://en.wikipedia.org/wiki/Rollinghttp://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Moment_(physics)http://en.wikipedia.org/wiki/Moment_(physics)http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Wheelhttp://en.wikipedia.org/wiki/Wheelhttp://en.wikipedia.org/wiki/Wheelhttp://en.wikipedia.org/wiki/Wheel#Etymologyhttp://en.wikipedia.org/wiki/Wheel#Historyhttp://en.wikipedia.org/wiki/Wheel#Timelinehttp://en.wikipedia.org/wiki/Wheel#Mechanics_and_functionhttp://en.wikipedia.org/wiki/Wheel#Constructionhttp://en.wikipedia.org/wiki/Wheel#Rimhttp://en.wikipedia.org/wiki/Wheel#Hubhttp://en.wikipedia.org/wiki/Wheel#Spokeshttp://en.wikipedia.org/wiki/Wheel#Wirehttp://en.wikipedia.org/wiki/Wheel#Tirehttp://en.wikipedia.org/wiki/Wheel#Alternativeshttp://en.wikipedia.org/wiki/Wheel#In_semioticshttp://en.wikipedia.org/wiki/Wheel#Galleryhttp://en.wikipedia.org/wiki/Wheel#See_alsohttp://en.wikipedia.org/wiki/Wheel#Referenceshttp://en.wikipedia.org/wiki/Wheel#External_linkshttp://en.wikipedia.org/w/index.php?title=Wheel&action=edit&section=1http://en.wiktionary.org/wiki/wheelhttp://en.wikipedia.org/wiki/Old_Englishhttp://en.wikipedia.org/wiki/Old_Englishhttp://en.wikipedia.org/wiki/Proto-Germanic_languagehttp://en.wikipedia.org/wiki/Proto-Germanic_languagehttp://en.wikipedia.org/wiki/Proto-Germanic_languagehttp://en.wikipedia.org/wiki/Proto-Germanic_languagehttp://en.wikipedia.org/wiki/Proto-Indo-European_languagehttp://en.wikipedia.org/wiki/Wheel#cite_note-0http://en.wikipedia.org/wiki/Wheel#cite_note-0http://en.wikipedia.org/wiki/Greek_languagehttp://en.wikipedia.org/wiki/Sanskrithttp://en.wikipedia.org/wiki/Sanskrithttp://en.wikipedia.org/wiki/Chakrahttp://en.wikipedia.org/wiki/Chakrahttp://en.wikipedia.org/wiki/Old_Church_Slavonichttp://en.wikipedia.org/wiki/Old_Church_Slavonichttp://en.wikipedia.org/wiki/Old_Church_Slavonichttp://en.wikipedia.org/wiki/Wheel#cite_note-1http://en.wiktionary.org/wiki/rotahttp://en.wiktionary.org/wiki/rotahttp://en.wikipedia.org/wiki/Wheel#cite_note-2http://en.wikipedia.org/w/index.php?title=Wheel&action=edit&section=2http://en.wikipedia.org/wiki/Bearing_(mechanical)http://en.wikipedia.org/wiki/Wheel_and_axlehttp://en.wikipedia.org/wiki/Simple_machinehttp://en.wikipedia.org/wiki/Ship's_wheelhttp://en.wikipedia.org/wiki/Steering_wheelhttp://en.wikipedia.org/wiki/Potter's_wheelhttp://en.wikipedia.org/wiki/Flywheelhttp://en.wikipedia.org/wiki/Transporthttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Rollinghttp://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Moment_(physics)http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Wheelhttp://en.wikipedia.org/wiki/Wheel#Etymologyhttp://en.wikipedia.org/wiki/Wheel#Historyhttp://en.wikipedia.org/wiki/Wheel#Timelinehttp://en.wikipedia.org/wiki/Wheel#Mechanics_and_functionhttp://en.wikipedia.org/wiki/Wheel#Constructionhttp://en.wikipedia.org/wiki/Wheel#Rimhttp://en.wikipedia.org/wiki/Wheel#Hubhttp://en.wikipedia.org/wiki/Wheel#Spokeshttp://en.wikipedia.org/wiki/Wheel#Wirehttp://en.wikipedia.org/wiki/Wheel#Tirehttp://en.wikipedia.org/wiki/Wheel#Alternativeshttp://en.wikipedia.org/wiki/Wheel#In_semioticshttp://en.wikipedia.org/wiki/Wheel#Galleryhttp://en.wikipedia.org/wiki/Wheel#See_alsohttp://en.wikipedia.org/wiki/Wheel#Referenceshttp://en.wikipedia.org/wiki/Wheel#External_linkshttp://en.wikipedia.org/w/index.php?title=Wheel&action=edit&section=1http://en.wiktionary.org/wiki/wheelhttp://en.wikipedia.org/wiki/Old_Englishhttp://en.wikipedia.org/wiki/Proto-Germanic_languagehttp://en.wikipedia.org/wiki/Proto-Germanic_languagehttp://en.wikipedia.org/wiki/Proto-Indo-European_languagehttp://en.wikipedia.org/wiki/Wheel#cite_note-0http://en.wikipedia.org/wiki/Greek_languagehttp://en.wikipedia.org/wiki/Sanskrithttp://en.wikipedia.org/wiki/Chakrahttp://en.wikipedia.org/wiki/Old_Church_Slavonichttp://en.wikipedia.org/wiki/Wheel#cite_note-1http://en.wiktionary.org/wiki/rotahttp://en.wikipedia.org/wiki/Wheel#cite_note-2http://en.wikipedia.org/w/index.php?title=Wheel&action=edit&section=2


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A depiction of anonager-drawn cart on the Sumerian"battle standard ofUr" (circa 2500 BC)

A figurine featuring theNew World's independently invented wheel

Evidence of wheeled vehicles appears from the mid-4th millennium BC, near-simultaneously

in Mesopotamia, the Northern Caucasus (Maykop culture) and Central Europe, so that the question of

which culture originally invented the wheeled vehicle remains unresolved and under debate.

The earliest well-dated depiction of a wheeled vehicle (here a wagonfour wheels, two axles), is on

the Bronocice pot, a ca. 35003350 BC clay pot excavated in a Funnelbeaker culture settlement in

southern Poland.[4]

The wheeled vehicle spread from the area of its first occurrence (Mesopotamia, Caucasus, Balkans,

Central Europe) across Eurasia, reaching the Indus Valleyby the 3rd millennium BC. During the 2nd

millennium BC, the spoke-wheeled chariotspread at an increased pace, reaching

both China and Scandinavia by 1200 BC. In China, the wheel was certainly present with the adoption

of the chariot in ca. 1200 BC,[5] although Barbieri-Low[6] argues for earlier Chinese wheeled vehicles,

circa 2000 BC.

Although they did not develop the wheel proper, the Olmecand certain other western

hemispherecultures seem to have approached it, as wheel-like worked stones have been found on

objects identified as children's toys dating to about 1500 BC.[7]

It is thought that the primary obstacle tolarge-scale development of the wheel in the Western hemisphere was the absence of domesticated

large animals which could be used to pull wheeled carriages. The closest relative ofcattle present in

Americas in pre-Columbian times, theAmerican Bison, is difficult to domesticate and was never

domesticated by Native Americans; several horse species existed until about 12,000 years ago, but
http://en.wikipedia.org/wiki/Onagerhttp://en.wikipedia.org/wiki/Onagerhttp://en.wikipedia.org/wiki/Onagerhttp://en.wikipedia.org/wiki/Sumerhttp://en.wikipedia.org/wiki/Sumerhttp://en.wikipedia.org/wiki/Urhttp://en.wikipedia.org/wiki/Urhttp://en.wikipedia.org/wiki/New_Worldhttp://en.wikipedia.org/wiki/New_Worldhttp://en.wikipedia.org/wiki/New_Worldhttp://en.wikipedia.org/wiki/4th_millennium_BChttp://en.wikipedia.org/wiki/4th_millennium_BChttp://en.wikipedia.org/wiki/Mesopotamiahttp://en.wikipedia.org/wiki/Caucasushttp://en.wikipedia.org/wiki/Maykop_culturehttp://en.wikipedia.org/wiki/Central_Europehttp://en.wikipedia.org/wiki/Bronocice_pothttp://en.wikipedia.org/wiki/Funnelbeaker_culturehttp://en.wikipedia.org/wiki/Wheel#cite_note-3http://en.wikipedia.org/wiki/Indus_Valley_Civilizationhttp://en.wikipedia.org/wiki/Indus_Valley_Civilizationhttp://en.wikipedia.org/wiki/Chariothttp://en.wikipedia.org/wiki/Chariothttp://en.wikipedia.org/wiki/Bronze_Age_Chinahttp://en.wikipedia.org/wiki/Nordic_Bronze_Agehttp://en.wikipedia.org/wiki/Wheel#cite_note-4http://en.wikipedia.org/wiki/Wheel#cite_note-4http://en.wikipedia.org/wiki/Wheel#cite_note-5http://en.wikipedia.org/wiki/Olmechttp://en.wikipedia.org/wiki/Olmechttp://en.wikipedia.org/wiki/Cultureshttp://en.wikipedia.org/wiki/Cultureshttp://en.wikipedia.org/wiki/Wheel#cite_note-6http://en.wikipedia.org/wiki/Cattlehttp://en.wikipedia.org/wiki/Cattlehttp://en.wikipedia.org/wiki/American_Bisonhttp://en.wikipedia.org/wiki/File:Remojadas_Wheeled_Figurine.jpghttp://en.wikipedia.org/wiki/File:Remojadas_Wheeled_Figurine.jpghttp://en.wikipedia.org/wiki/File:Ur_chariot.jpghttp://en.wikipedia.org/wiki/File:Ur_chariot.jpghttp://en.wikipedia.org/wiki/Onagerhttp://en.wikipedia.org/wiki/Sumerhttp://en.wikipedia.org/wiki/Urhttp://en.wikipedia.org/wiki/New_Worldhttp://en.wikipedia.org/wiki/4th_millennium_BChttp://en.wikipedia.org/wiki/Mesopotamiahttp://en.wikipedia.org/wiki/Caucasushttp://en.wikipedia.org/wiki/Maykop_culturehttp://en.wikipedia.org/wiki/Central_Europehttp://en.wikipedia.org/wiki/Bronocice_pothttp://en.wikipedia.org/wiki/Funnelbeaker_culturehttp://en.wikipedia.org/wiki/Wheel#cite_note-3http://en.wikipedia.org/wiki/Indus_Valley_Civilizationhttp://en.wikipedia.org/wiki/Chariothttp://en.wikipedia.org/wiki/Bronze_Age_Chinahttp://en.wikipedia.org/wiki/Nordic_Bronze_Agehttp://en.wikipedia.org/wiki/Wheel#cite_note-4http://en.wikipedia.org/wiki/Wheel#cite_note-5http://en.wikipedia.org/wiki/Olmechttp://en.wikipedia.org/wiki/Cultureshttp://en.wikipedia.org/wiki/Wheel#cite_note-6http://en.wikipedia.org/wiki/Cattlehttp://en.wikipedia.org/wiki/American_Bison


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ultimately went extinct.[8] The only large animal that was domesticated in the Western hemisphere,

the llama, did not spread far beyond theAndes by the time of the arrival of Columbus.

Nubians from after about 400 B.C. used wheels for spinning pottery and as water wheels.[9][10]It is

thought that Nubian waterwheels may have been ox-driven[11] It is also known that Nubians used

horse-driven chariots imported from Egypt.[12]

The invention of the wheel thus falls in the lateNeolithic, and may be seen in conjunction with other

technological advances that gave rise to the early Bronze Age. Note that this implies the passage of

several wheel-less millennia even after the invention of agricultureand of pottery:

95006500 BC:Aceramic Neolithic

65004500 BC: Ceramic Neolithic (Halafian)

Ca. 4500 BC: invention of the potter's wheel, beginning of the Chalcolithic(Ubaid period)

45003300 BC: Chalcolithic, earliest wheeled vehicles,domestication of the horse

33002200 BC: Early Bronze Age

22001550 BC: Middle Bronze Age, invention of thespoked wheel and the chariot

Wide usage of the wheel was probably delayed because smoothroadswere needed for wheels to be

effective. Carrying goods on the back would have been the preferred method of transportation over

surfaces that contained many obstacles. The lack of developed roads prevented wide adoption of the

wheel for transportation until well into the 20th century in less developed areas.

Early wheels were simple wooden disks with a hole for the axle. Because of the structure ofwood, a

horizontal slice of a tree trunk is not suitable, as it does not have the structural strength to support

weight without collapsing; rounded pieces of longitudinal boards are required. The oldest known

example of a wooden wheel and its axle were found in 2003 in theLjubljana Marshes some 20 km

south ofLjubljana, the capital of Slovenia. According to the radiocarbon dating, it is between 5,100 and

5,350 years old.[13] It has a diameter of 72 centimetres (28 in) and has been made ofashwood,

whereas its axle has been made ofoak.[14]

The spoked wheel was invented more recently, and allowed the construction of lighter and swifter

vehicles. In the Harappan civilization of the Indus Valley and Northwestern India, we find toy-cart

wheels made of clay with spokes painted or in relief, [15]and the symbol of the spoked wheel in the

script of the seals,[16] already in the second half of the 3rd millennium BC. The earliest known examples

of wooden spoked wheels are in the context of theAndronovo culture, dating to ca 2000 BC. Soon

after this, horse cultures of theCaucasus region used horse-drawn spoked-wheel warchariots for the

greater part of three centuries. They moved deep into the Greek peninsula where they joined with the

existing Mediterranean peoples to give rise, eventually, to classical Greece after the breaking

ofMinoan dominance and consolidations led by pre-classicalSpartaandAthens.Celtic chariots

introduced aniron rim around the wheel in the 1st millennium BC. The spoked wheel was in continued

use without major modification until the 1870s, when wire wheels and pneumatic tires were invented.[17]
http://en.wikipedia.org/wiki/Wheel#cite_note-7http://en.wikipedia.org/wiki/Wheel#cite_note-7http://en.wikipedia.org/wiki/Llamahttp://en.wikipedia.org/wiki/Andeshttp://en.wikipedia.org/wiki/Nubiahttp://en.wikipedia.org/wiki/Potteryhttp://en.wikipedia.org/wiki/Water_wheelshttp://en.wikipedia.org/wiki/Water_wheelshttp://en.wikipedia.org/wiki/Wheel#cite_note-8http://en.wikipedia.org/wiki/Wheel#cite_note-9http://en.wikipedia.org/wiki/Wheel#cite_note-9http://en.wikipedia.org/wiki/Wheel#cite_note-10http://en.wikipedia.org/wiki/Egypthttp://en.wikipedia.org/wiki/Wheel#cite_note-11http://en.wikipedia.org/wiki/Wheel#cite_note-11http://en.wikipedia.org/wiki/Neolithichttp://en.wikipedia.org/wiki/Neolithichttp://en.wikipedia.org/wiki/Bronze_Agehttp://en.wikipedia.org/wiki/Bronze_Agehttp://en.wikipedia.org/wiki/Neolithic_Revolutionhttp://en.wikipedia.org/wiki/Aceramic_Neolithichttp://en.wikipedia.org/wiki/Neolithichttp://en.wikipedia.org/wiki/Halafianhttp://en.wikipedia.org/wiki/Potter's_wheelhttp://en.wikipedia.org/wiki/Chalcolithichttp://en.wikipedia.org/wiki/Chalcolithichttp://en.wikipedia.org/wiki/Ubaid_periodhttp://en.wikipedia.org/wiki/Chalcolithichttp://en.wikipedia.org/wiki/Chalcolithichttp://en.wikipedia.org/wiki/Domestication_of_the_horsehttp://en.wikipedia.org/wiki/Domestication_of_the_horsehttp://en.wikipedia.org/wiki/Early_Bronze_Agehttp://en.wikipedia.org/wiki/Middle_Bronze_Agehttp://en.wikipedia.org/wiki/Spokehttp://en.wikipedia.org/wiki/Spokehttp://en.wikipedia.org/wiki/Roadhttp://en.wikipedia.org/wiki/Roadhttp://en.wikipedia.org/wiki/Roadhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Ljubljana_Marsheshttp://en.wikipedia.org/wiki/Ljubljana_Marsheshttp://en.wikipedia.org/wiki/Ljubljanahttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Wheel#cite_note-Slovenia-12http://en.wikipedia.org/wiki/Wheel#cite_note-Slovenia-12http://en.wikipedia.org/wiki/Fraxinushttp://en.wikipedia.org/wiki/Fraxinushttp://en.wikipedia.org/wiki/Oakhttp://en.wikipedia.org/wiki/Oakhttp://en.wikipedia.org/wiki/Wheel#cite_note-13http://en.wikipedia.org/wiki/Wheel#cite_note-13http://en.wikipedia.org/wiki/Spokehttp://en.wikipedia.org/wiki/Wheel#cite_note-14http://en.wikipedia.org/wiki/Wheel#cite_note-14http://en.wikipedia.org/wiki/Wheel#cite_note-15http://en.wikipedia.org/wiki/Wheel#cite_note-15http://en.wikipedia.org/wiki/Andronovo_culturehttp://en.wikipedia.org/wiki/Caucasushttp://en.wikipedia.org/wiki/Caucasushttp://en.wikipedia.org/wiki/Chariotshttp://en.wikipedia.org/wiki/Chariotshttp://en.wikipedia.org/wiki/Minoan_civilizationhttp://en.wikipedia.org/wiki/Minoan_civilizationhttp://en.wikipedia.org/wiki/Spartahttp://en.wikipedia.org/wiki/Spartahttp://en.wikipedia.org/wiki/Spartahttp://en.wikipedia.org/wiki/Athenshttp://en.wikipedia.org/wiki/Athenshttp://en.wikipedia.org/wiki/Celthttp://en.wikipedia.org/wiki/Celthttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Tirehttp://en.wikipedia.org/wiki/Wheel#cite_note-16http://en.wikipedia.org/wiki/Wheel#cite_note-16http://en.wikipedia.org/wiki/Wheel#cite_note-7http://en.wikipedia.org/wiki/Llamahttp://en.wikipedia.org/wiki/Andeshttp://en.wikipedia.org/wiki/Nubiahttp://en.wikipedia.org/wiki/Potteryhttp://en.wikipedia.org/wiki/Water_wheelshttp://en.wikipedia.org/wiki/Wheel#cite_note-8http://en.wikipedia.org/wiki/Wheel#cite_note-9http://en.wikipedia.org/wiki/Wheel#cite_note-10http://en.wikipedia.org/wiki/Egypthttp://en.wikipedia.org/wiki/Wheel#cite_note-11http://en.wikipedia.org/wiki/Neolithichttp://en.wikipedia.org/wiki/Bronze_Agehttp://en.wikipedia.org/wiki/Neolithic_Revolutionhttp://en.wikipedia.org/wiki/Aceramic_Neolithichttp://en.wikipedia.org/wiki/Neolithichttp://en.wikipedia.org/wiki/Halafianhttp://en.wikipedia.org/wiki/Potter's_wheelhttp://en.wikipedia.org/wiki/Chalcolithichttp://en.wikipedia.org/wiki/Ubaid_periodhttp://en.wikipedia.org/wiki/Chalcolithichttp://en.wikipedia.org/wiki/Domestication_of_the_horsehttp://en.wikipedia.org/wiki/Early_Bronze_Agehttp://en.wikipedia.org/wiki/Middle_Bronze_Agehttp://en.wikipedia.org/wiki/Spokehttp://en.wikipedia.org/wiki/Roadhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Ljubljana_Marsheshttp://en.wikipedia.org/wiki/Ljubljanahttp://en.wikipedia.org/wiki/Radiocarbon_datinghttp://en.wikipedia.org/wiki/Wheel#cite_note-Slovenia-12http://en.wikipedia.org/wiki/Fraxinushttp://en.wikipedia.org/wiki/Oakhttp://en.wikipedia.org/wiki/Wheel#cite_note-13http://en.wikipedia.org/wiki/Spokehttp://en.wikipedia.org/wiki/Wheel#cite_note-14http://en.wikipedia.org/wiki/Wheel#cite_note-15http://en.wikipedia.org/wiki/Andronovo_culturehttp://en.wikipedia.org/wiki/Caucasushttp://en.wikipedia.org/wiki/Chariotshttp://en.wikipedia.org/wiki/Minoan_civilizationhttp://en.wikipedia.org/wiki/Spartahttp://en.wikipedia.org/wiki/Athenshttp://en.wikipedia.org/wiki/Celthttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Tirehttp://en.wikipedia.org/wiki/Wheel#cite_note-16


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The invention of the wheel has also been important fortechnologyin general, important applications

including the water wheel, thecogwheel(see alsoantikythera mechanism), thespinning wheel, and

the astrolabe ortorquetum. More modern descendants of the wheel include the propeller, thejet

engine, the flywheel (gyroscope) and the turbine.

[edit]Timeline

Bronze Age disk wheel as depicted on theStandard of Ur(ca. 2500 BC)

Classical Greek four-spokedchariot-wheel (as aLinear B glyph), in use from the 15th century BC. Hittite and Egyptian chariots

tended to have six spokes, Iron Age Assyrian ones eight.

Bronze Age "wheel pendants" of theUrnfield culture(ca. 1200 BC), found in Zrich (Swiss National Museum)
http://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Water_wheelhttp://en.wikipedia.org/wiki/Cogwheelhttp://en.wikipedia.org/wiki/Cogwheelhttp://en.wikipedia.org/wiki/Antikythera_mechanismhttp://en.wikipedia.org/wiki/Antikythera_mechanismhttp://en.wikipedia.org/wiki/Spinning_wheelhttp://en.wikipedia.org/wiki/Spinning_wheelhttp://en.wikipedia.org/wiki/Astrolabehttp://en.wikipedia.org/wiki/Torquetumhttp://en.wikipedia.org/wiki/Torquetumhttp://en.wikipedia.org/wiki/Propellerhttp://en.wikipedia.org/wiki/Jet_enginehttp://en.wikipedia.org/wiki/Jet_enginehttp://en.wikipedia.org/wiki/Flywheelhttp://en.wikipedia.org/wiki/Gyroscopehttp://en.wikipedia.org/wiki/Turbinehttp://en.wikipedia.org/w/index.php?title=Wheel&action=edit&section=3http://en.wikipedia.org/wiki/Standard_of_Urhttp://en.wikipedia.org/wiki/Standard_of_Urhttp://en.wikipedia.org/wiki/Chariothttp://en.wikipedia.org/wiki/Chariothttp://en.wikipedia.org/wiki/Linear_Bhttp://en.wikipedia.org/wiki/Linear_Bhttp://en.wikipedia.org/wiki/Urnfield_culturehttp://en.wikipedia.org/wiki/Urnfield_culturehttp://en.wikipedia.org/wiki/Urnfield_culturehttp://en.wikipedia.org/wiki/Swiss_National_Museumhttp://en.wikipedia.org/wiki/Swiss_National_Museumhttp://en.wikipedia.org/wiki/File:Wheel_Iran.jpghttp://en.wikipedia.org/wiki/File:Radanhaenger-edited.jpghttp://en.wikipedia.org/w/index.php?title=File:Linear_B_Syllable_B077_KA.svg&page=1http://en.wikipedia.org/wiki/File:Ur_wheel.jpghttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Water_wheelhttp://en.wikipedia.org/wiki/Cogwheelhttp://en.wikipedia.org/wiki/Antikythera_mechanismhttp://en.wikipedia.org/wiki/Spinning_wheelhttp://en.wikipedia.org/wiki/Astrolabehttp://en.wikipedia.org/wiki/Torquetumhttp://en.wikipedia.org/wiki/Propellerhttp://en.wikipedia.org/wiki/Jet_enginehttp://en.wikipedia.org/wiki/Jet_enginehttp://en.wikipedia.org/wiki/Flywheelhttp://en.wikipedia.org/wiki/Gyroscopehttp://en.wikipedia.org/wiki/Turbinehttp://en.wikipedia.org/w/index.php?title=Wheel&action=edit&section=3http://en.wikipedia.org/wiki/Standard_of_Urhttp://en.wikipedia.org/wiki/Chariothttp://en.wikipedia.org/wiki/Linear_Bhttp://en.wikipedia.org/wiki/Urnfield_culturehttp://en.wikipedia.org/wiki/Swiss_National_Museum


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An Early Iron Age spoked wheel fromChoqa Zanbil(ca. 1000 BC, National Museum of Iran)

Wheel of theEtruscan chariot(ca. 530 BC)

The classic spoked wheel with hub and iron rim, in use from about 500 BC (Iron Age Europe) until the 20th century AD

Penny-farthing bicycle (1882)

Modern motorcyclealloy wheelwith inflatable tireanddisc brake

[edit]Mechanics and function

Main article: wheel and axle
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The wheel is a device that enables efficient movement of an object across a surface where there is a

force pressing the object to the surface. Common examples are a cart pulled by a horse, and the

rollers on an aircraft flap mechanism.

Wheels are used in conjunction withaxles; either the wheel turns on the axle, or the axle turns in the

object body. The mechanics are the same in either case.

The low resistance to motion (compared to dragging) is explained as follows (refer to friction):

the normal force at the sliding interface is the same.

the sliding distance is reduced for a given distance of travel.

the coefficient of friction at the interface is usually lower.

Bearingsare used to help reduce friction at the interface. In the simplest and oldest case the bearing is

just a round hole through which the axle passes (a "plain bearing").

Example:

If a 100kgobject is dragged for 10 m along a surface with thecoefficient of friction= 0.5,

the normal force is 981Nand theworkdone (required energy) is (work=force x distance) 981

0.5 10 = 4905joules.

Now give the object 4 wheels. The normal force between the 4 wheels and axles is the same

(in total) 981 N. Assume, for wood,= 0.25, and say the wheeldiameteris 1000 mm and axle

diameter is 50 mm. So while the object still moves 10 m the sliding frictional surfaces only slide

over each other a distance of 0.5 m. The work done is 981 0.25 0.5 = 123 joules; the work

done has reduced to 1/40 of that of dragging.

Additional energy is lost from the wheel-to-road interface. This is termedrolling resistance which is

predominantly a deformation loss.

A wheel can also offer advantages in traversing irregular surfaces if the wheel radius is sufficiently

large compared to the irregularities.

The wheel alone is not a machine, but when attached to an axlein conjunction with bearing, it forms

the wheel and axle, one of thesimple machines. A driven wheel is an example of a wheel and axle.

Note that wheels pre-date driven wheels by about 6000 years.

[edit]Construction

[edit]Rim

Main article: Rim (wheel)
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Analuminumalloy wheel

The rim is the "outer edge of a wheel, holding the tire." [18]It makes up the outer circular design of the

wheel on which the inside edge of the tireis mounted on vehicles such asautomobiles.[19] For example,

on a bicycle wheel the rim is a large hoop attached to the outer ends of the spokes of the wheel that

holds the tire and tube.

In the 1st millennium BC an iron rim was introduced around the wooden wheels ofchariots.

[edit]Hub

The hub is the center of the wheel, and typically houses abearing, and is where the spokes meet.

A hubless wheel(also known as a rim-rider or centerless wheel) is a type of wheel with no centerhub.

More specifically, the hub is actually almost as big as the wheel itself. The axleis hollow, following the

wheel at very closetolerances.

[edit]Spokes

Main article: spoke

A spoked wheel on display at TheNational Museum of Iran, inTehran. The wheel is dated to the late 2nd millennium BC and was excavated atChoqa

Zanbil.

A spoke is one of some number of rods radiating from the center of a wheel (the hub where

the axleconnects), connecting the hub with the round traction surface. The term originally referred to

portions of a log which had been split lengthwise into four or six sections. The radial members of a

wagon wheel were made by carving a spoke (from a log) into their finished shape. Aspokeshaveis
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a tooloriginally developed for this purpose. Eventually, the term spoke was more commonly applied to

the finished product of the wheelwright's work, than to the materials he used.

[edit]Wire

Main article: wire wheel

The rims ofwire wheels (or "wire spoked wheels") are connected to their hubs by wirespokes.

Although these wiresare generally stiffer than a typical wire rope, they function mechanically the same

as tensioned flexible wires, keeping the rim true while supporting applied loads.

Wire wheels are used on mostbicyclesand still used on many motorcycles. They were invented by

aeronautical engineerGeorge Cayleyand first used in bicycles by James Starley. A process of

assembling wire wheels is described as wheelbuilding.

A 1957 MGA Automobile with wire wheels

[edit]Tire

Main article: tire

Stacked and standing car tires

A tire (inAmerican English and Canadian English) ortyre (in someCommonwealth Nationssuch as

UK, and Australia) is a ring-shaped covering that fits around a wheelrim to protect it and enable better

vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in

close contact with the ground. The word itself may be derived from the word "tie," which refers to the
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outer steel ring part of a wooden cart wheel that ties the wood segments together (see Etymology

below).

The fundamental materials of modern tires aresynthetic rubber,natural rubber, fabric and wire, along

with other compound chemicals. They consist of a tread and a body. The tread providestraction while

the body ensures support. Before rubber was invented, the first versions of tires were simply bands of

metal that fitted around wooden wheels to prevent wear and tear. Today, the vast majority of tires

arepneumaticinflatable structures, comprising a doughnut-shaped body of cords and wires encased

in rubber and generally filled with compressed air to form an inflatable cushion. Pneumatic tires are

used on many types of vehicles, such ascars, bicycles, motorcycles, trucks,earthmovers, andaircraft.

[edit]Alternatives

While wheels are very widely used for ground transport, there are alternatives, some of which are

suitable for terrain where wheels are ineffective. Alternative methods for ground transport without

wheels (wheel-less transport) include:

Being raised by electromagneticenergy (maglev trainand other vehicles) Dragging with runners (sled) or without (travois)

Being raised by air pressure (hovercraft)

Riding an animal such as a horse

Human powered:

Walking on one's own legs

Being carried (litter/sedan chairorstretcher)

A walking machine

Caterpillar tracks(although it is still operated by wheels)

Pedrail wheels, using aspects of both wheel and caterpillar track

Spheres, as used byDysonvacuum cleaners and hamster balls
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All About Wheel

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