A wheel is a circular component that is intended to rotate on an axle bearing. The wheel is one of the key components of the wheel and axle which is one of the six 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 a ship's wheel, steering wheel, potter's wheel and flywheel. Common examples are found in transport applications. A wheel greatly reduces friction by facilitating motion by rolling together with the use of axles. In order for wheels to rotate, a moment needs to be applied to the wheel about its axis, either by way of gravity or by the application of another external force or torque. Using the wheel, Sumerians invented a contraption that spins clay as a potter shapes it into the desired object.
1 Etymology 2 History 3 Mechanics and function 4 Construction
4.1 Rim 4.2 Hub 4.3 Spokes
4.4 Tire/Tyre 4.5 Trywheel
5 Patenting the wheel 6 Alternatives 7 Symbolism 8 See also 9 References 10 External links
The English word wheel comes from the
4500–3300 BCE: Copper Age, invention of the potter's wheel; earliest
wooden wheels (disks with a hole for the axle); earliest wheeled
vehicles, domestication of the horse
3300–2200 BCE: Early
A depiction of an onager-drawn cart on the Sumerian "battle standard of Ur" (c. 2500 BC)
A figurine featuring the New World's independently invented wheel
Although large-scale use of wheels did not occur in the Americas prior
to European contact, numerous small wheeled artifacts, identified as
children's toys, have been found in Mexican archeological sites, some
dating to about 1500 BC. It is thought that the primary obstacle
to large-scale development of the wheel in the Americas was the
absence of domesticated large animals which could be used to pull
wheeled carriages. The closest relative of cattle present in
Americas in pre-Columbian times, the American Bison, is difficult to
domesticate and was never domesticated by Native Americans; several
horse species existed until about 12,000 years ago, but ultimately
became extinct. The only large animal that was domesticated in the
Western hemisphere, the llama, did not spread far beyond the
Solid wheels on a heavy temple car, contrasted with the lighter wire-spoked wheels of the black roadster bicycle in the foreground
Early wheels were simple wooden disks with a hole for the axle. Some
of the earliest wheels were made from horizontal slices of tree
trunks. Because of the uneven structure of wood, a wheel made from a
horizontal slice of a tree trunk will tend to be inferior to one made
from rounded pieces of longitudinal boards.
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, toy-cart
wheels made of clay with lines which have been interpreted as spokes
painted or in relief  as well as a symbol interpreted as a spoked
wheel in the script of the seals that date from the second half of
the 3rd millennium
Twentieth-century solid wheel made of wooden boards, bound with a metal wheel rim
Spoked wheels on the ancient Etruscan Monteleone chariot, 2nd quarter of the 6th century B.C.[contradictory]
Spoked wheel with bronze sheeting from Árokalja. 1000 BC.
Radially- (left) and tangentially- (right) wire-spoked wheels, both with pneumatic tires.
Cast alloy wheel on a folding bicycle, with a pneumatic tire.
Mechanics and function Main article: wheel and axle 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.
Bearings are 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 100 kg object is dragged for 10 m along a surface with the coefficient of friction μ = 0.5, the normal force is 981 N and the work done (required energy) is (work=force x distance) 981 × 0.5 × 10 = 4905 joules. 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, μ = 0.25, and say the wheel diameter is 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
termed rolling resistance which is predominantly a deformation loss.
This energy is also lowered by the use of a wheel (in comparison to
dragging) because the net force on the contact point between the road
and the wheel is almost perpendicular to the ground, and hence,
generates an almost zero net work. This depends on the nature of the
ground, of the material of the wheel, its inflation in the case of a
tire, the net torque exerted by the eventual engine, and many other
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 axle in
conjunction with bearing, it forms the wheel and axle, one of the
simple machines. A driven wheel is an example of a wheel and axle.
Wheels pre-date driven wheels by about 6000 years, themselves an
evolution of using round logs as rollers to move a heavy load—a
practice going back in pre-history so far that it has not been dated.
This article is about structure of wheel. For making of wire-spoked
wheels, see Wheelbuilding. For making of non-wire spoked wheels, see
An aluminium alloy wheel
The rim is the "outer edge of a wheel, holding the tire." It makes
up the outer circular design of the wheel on which the inside edge of
the tire is mounted on vehicles such as automobiles. 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
A spoked wheel on display at The National Museum of Iran, in Tehran.
The wheel is dated to the late 2nd millennium
A spoke is one of some number of rods radiating from the center of a
wheel (the hub where the axle connects), 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. A spokeshave is a tool originally
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 used.
Main article: wire wheel
The rims of wire wheels (or "wire spoked wheels") are connected to
their hubs by wire spokes. Although these wires are generally stiffer
than a typical wire rope, they function mechanically the same as
tensioned flexible wires, keeping the rim true while supporting
A 1957 MGA automobile with wire wheels
Tire/Tyre Main article: tire
Stacked and standing car tires
A tire (in
Joseph Ledwinka, patent US808765 of 1906 Manuel Herrera de Hora, patent US836578 of 1906 Louis Mékarski, patent GB190702860 of 1907 William Morris, patent US1159786 of 1915
In many cases, the idea was to create a resilient wheel. This function is now provided by what's known as the pneumatic tyre. 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 include:
Electromagnetic maglev trains
A recent invention is the so-called Liddiard Wheel, which claims to be
a superior omnidirectional wheel.
The wheel has also become a strong cultural and spiritual metaphor for
a cycle or regular repetition (see chakra, reincarnation, Yin and Yang
among others). As such and because of the difficult terrain, wheeled
vehicles were forbidden in old Tibet. The wheel in ancient
Types: Alloy wheel, Artillery wheel,
^ "wheel". Online Etymology Dictionary.
^ "American Heritage Dictionary Entry: wheel". Houghton Mifflin
Harcourt Publishing Company.
^ V. Gordon Childe (1928). New Light on the Most Ancient East.
^ D. T. Potts (2012). A Companion to the Archaeology of the Ancient
Near East. p. 285.
^ Moorey, Peter Roger Stuart (1999) . Ancient Mesopotamian
Materials and Industries: The Archaeological Evidence. Winona Lake,
Indiana: Eisenbrauns. p. 146. ISBN 9781575060422.
^ Anthony, David A. (2007). The horse, the wheel, and language: how
Bronze-Age riders from the Eurasian steppes shaped the modern world.
Princeton, N.J: Princeton University Press. p. 67.
^ Velušček, A.; Čufar, K. and Zupančič, M. (2009) "Prazgodovinsko
leseno kolo z osjo s kolišča Stare gmajne na Ljubljanskem barju",
pp. 197–222 in A. Velušček (ed.). Koliščarska naselbina Stare
gmajne in njen as. Ljubljansko barje v 2. polovici 4. tisočletja pr.
Kr. Opera Instituti Archaeologici Sloveniae 16. Ljubljana.
^ Fowler, Chris; Harding, Jan and Hofmann, Daniela (eds.) (2015). The
Oxford Handbook of
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Look up wheel in Wiktionary, the free dictionary.
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