117-439: A wheel is a rotating component (typically circular in shape) that is intended to turn 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
234-401: A propeller shaft or tailshaft ) which transmits the rotational force to a drive axle at the rear of the vehicle. The drive axle may be a live axle , but modern rear-wheel drive automobiles generally use a split axle with a differential. In this case, one half-axle or half-shaft connects the differential with the left rear wheel, a second half-shaft does the same with the right rear wheel; thus
351-443: A ship's wheel , steering wheel , potter's wheel , and flywheel . Common examples can be found in transport applications. A wheel 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 . The English word wheel comes from
468-426: A complicated and extensive syllabary. A considerable amount of Babylonian literature was translated from Sumerian originals, and the language of religion and law long continued to be the old agglutinative language of Sumer. Vocabularies, grammars, and interlinear translations were compiled for the use of students, as well as commentaries on the older texts and explanations of obscure words and phrases. The characters of
585-429: A differential (kart racing). However, other go-karts have two rear drive wheels too. Some dump trucks and trailers may be configured with a lift axle (also known as an airlift axle or drop axle ), which may be mechanically raised or lowered. The axle is lowered to increase the weight capacity, or to distribute the weight of the cargo over more wheels, for example, to cross a weight-restricted bridge. When not needed,
702-522: A full-floating axle is that even if an axle shaft (used to transmit torque or power) breaks, the wheel will not come off, preventing serious accidents. Mesopotamia Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system , in the northern part of the Fertile Crescent . Today, Mesopotamia is known as present-day Iraq . In the broader sense,
819-407: A heavy load—a practice going back in pre-history so far that it has not been dated. 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
936-612: A language of the Zagros possibly related to the Hurro-Urartuan language family , is attested in personal names, rivers and mountains and in various crafts. Akkadian came to be the dominant language during the Akkadian Empire and the Assyrian empires, but Sumerian was retained for administrative, religious, literary and scientific purposes. Different varieties of Akkadian were used until
1053-435: 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. 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
1170-482: A patient could not be cured physically, the Babylonian physicians often relied on exorcism to cleanse the patient from any curses . Esagil-kin-apli's Diagnostic Handbook was based on a logical set of axioms and assumptions, including the modern view that through the examination and inspection of the symptoms of a patient, it is possible to determine the patient's disease , its aetiology, its future development, and
1287-549: A precursor to the Socratic method . The Ionian philosopher Thales was influenced by Babylonian cosmological ideas. Ancient Mesopotamians had ceremonies each month. The theme of the rituals and festivals for each month was determined by at least six important factors: Some songs were written for the gods but many were written to describe important events. Although music and songs amused kings , they were also enjoyed by ordinary people who liked to sing and dance in their homes or in
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#17328378139171404-413: A protruding hub to which the axle shaft flange is bolted. The semi-floating axle setup is commonly used on half-ton and lighter 4×4 trucks in the rear. This setup allows the axle shaft to be the means of propulsion, and also support the weight of the vehicle. The main difference between the full- and semi-floating axle setups is the number of bearings. The semi-floating axle features only one bearing, while
1521-730: A recent hypothesis, the Archimedes' screw may have been used by Sennacherib, King of Assyria, for the water systems at the Hanging Gardens of Babylon and Nineveh in the 7th century BC, although mainstream scholarship holds it to be a Greek invention of later times. Later, during the Parthian or Sasanian periods, the Baghdad Battery , which may have been the world's first battery, was created in Mesopotamia. The Ancient Mesopotamian religion
1638-550: A sacred, ceremonial, literary, and scientific language in Mesopotamia until the 1st century AD. Libraries were extant in towns and temples during the Babylonian Empire. An old Sumerian proverb averred that "he who would excel in the school of the scribes must rise with the dawn." Women as well as men learned to read and write, and for the Semitic Babylonians, this involved knowledge of the extinct Sumerian language, and
1755-524: A single nor several inventors. Evidence of early wheeled carts has been found across the Middle East , in Europe , Eastern Europe , India and China . It is not known whether Chinese, Indians, Europeans and Mesopotamians invented the wheel independently. The invention of the solid wooden disk wheel falls into the late Neolithic , and may be seen in conjunction with other technological advances that gave rise to
1872-400: A single unit called a transaxle . The drive axle is a split axle with a differential and universal joints between the two half axles. Each half axle connects to the wheel by use of a constant velocity (CV) joint which allows the wheel assembly to move freely vertically as well as to pivot when making turns. In rear-wheel drive cars and trucks, the engine turns a driveshaft (also called
1989-589: A site of the Longshan Culture . Similar tracks were also found at Yanshi , a city of the Erlitou culture , dating to around 1700 BCE. The earliest evidence of spoked wheels in China comes from Qinghai , in the form of two wheel hubs from a site dated between 2000 and 1500 BCE.Wheeled vehicles were introduced to China from the west. In Britain, a large wooden wheel, measuring about 1 m (3.3 ft) in diameter,
2106-427: A slow development over centuries in many locales. Mesopotamian civilization was credited with the invention of the wheel by several, mainly old sources. Some recent sources either suggest that the wheel was invented independently in both Mesopotamia and Eastern Europe or credit prehistoric Eastern Europeans with the invention of the wheel, and that unlike other breakthrough inventions, the wheel cannot be attributed to
2223-404: 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 China is seen as a symbol of health and strength and used by some villages as a tool to predict future health and success. The diameter of the wheel
2340-427: A suspension and steering component. Conversely, many front-wheel drive cars have a one-piece rear beam axle. In other types of suspension systems, the axles serve only to transmit driving torque to the wheels: the position and angle of the wheel hubs is made independent from the axles by the function of the suspension system. This is typical of the independent suspensions found on most newer cars, and even SUVs, and on
2457-415: A table of Pythagorean triples and represents some of the most advanced mathematics prior to Greek mathematics. From Sumerian times, temple priesthoods had attempted to associate current events with certain positions of the planets and stars. This continued to Assyrian times, when Limmu lists were created as a year by year association of events with planetary positions, which, when they have survived to
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#17328378139172574-626: A tread and a body. The tread provides traction 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 are pneumatic inflatable 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 as cars , bicycles , motorcycles , trucks , earthmovers , and aircraft . Extreme off-road conditions have resulted in
2691-427: A turn at all. Several manufacturers offer computer-controlled airlifts so that the dead axles are automatically lowered when the main axle reaches its weight limit. The dead axles can still be lifted by the press of a button if needed, for better maneuverability. Lift axles were in use in the early 1940s. Initially, the axle was lifted by a mechanical device. Soon hydraulics replaced the mechanical lift system. One of
2808-510: A vast mountainous region. Overland routes in Mesopotamia usually follow the Euphrates because the banks of the Tigris are frequently steep and difficult. The climate of the region is semi-arid with a vast desert expanse in the north which gives way to a 15,000-square-kilometre (5,800 sq mi) region of marshes, lagoons, mudflats, and reed banks in the south. In the extreme south, the Euphrates and
2925-594: A wheeled vehicle appeared between 3631 and 3380 BCE in the Bronocice clay pot excavated in a Funnelbeaker culture settlement in southern Poland . In nearby Olszanica , a 2.2 m wide door was constructed for wagon entry; this barn was 40 m long with three doors, dated to 5000 BCE, and belonged to the neolithic Linear Pottery culture . Surviving evidence of a wheel-axle combination, from Stare Gmajne near Ljubljana in Slovenia ( Ljubljana Marshes Wooden Wheel ),
3042-580: Is an-ki , which refers to the god An and the goddess Ki . Their son was Enlil, the air god. They believed that Enlil was the most powerful god. He was the chief god of the pantheon . The numerous civilizations of the area influenced the Abrahamic religions , especially the Hebrew Bible . Its cultural values and literary influence are especially evident in the Book of Genesis . Giorgio Buccellati believes that
3159-401: Is a central shaft for a rotating wheel or gear . On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow
3276-414: Is a composite product, although it is probable that some of the stories are artificially attached to the central figure. Mesopotamian mathematics and science was based on a sexagesimal (base 60) numeral system . This is the source of the 60-minute hour, the 24-hour day, and the 360- degree circle. The Sumerian calendar was lunisolar, with three seven-day weeks of a lunar month. This form of mathematics
3393-403: Is a group of two or more axles situated close together. Truck designs use such a configuration to provide a greater weight capacity than a single axle. Semi-trailers usually have a tandem axle at the rear. Axles are typically made from SAE grade 41xx steel or SAE grade 10xx steel. SAE grade 41xx steel is commonly known as " chrome-molybdenum steel " (or "chrome-moly") while SAE grade 10xx steel
3510-553: Is a ring-shaped covering that fits around a wheel rim 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 outer steel ring part of a wooden cart wheel that ties the wood segments together (see Etymology above). The fundamental materials of modern tires are synthetic rubber , natural rubber , fabric, and wire, along with other compound chemicals. They consist of
3627-500: Is a single bearing at the end of the axle housing that carries the load from the axle and that the axle rotates through. To be "semi-floating" the axle shafts must be able to "float" in the housing, bearings and seals, and not subject to axial "thrust" and/or bearing preload. Needle bearings and separate lip seals are used in semi-floating axles with axle retained in the housing at their inner ends typically with circlips which are 3¾-round hardened washers that slide into grooves machined at
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3744-464: Is accurate to about six decimal digits, and is the closest possible three-place sexagesimal representation of √ 2 : The Babylonians were not interested in exact solutions, but rather approximations, and so they would commonly use linear interpolation to approximate intermediate values. One of the most famous tablets is the Plimpton 322 tablet , created around 1900–1600 BC, which gives
3861-441: Is attached to a separate shaft. Modern passenger cars have split-drive axles. In some designs, this allows independent suspension of the left and right wheels, and therefore a smoother ride. Even when the suspension is not independent, split axles permit the use of a differential, allowing the left and right drive wheels to be driven at different speeds as the automobile turns, improving traction and extending tire life. A tandem axle
3978-535: Is called an axle or axle shaft . However, in looser usage, an entire assembly including the surrounding axle housing (typically a casting ) is also called an axle . An even broader (somewhat figurative) sense of the word refers to every pair of parallel wheels on opposite sides of a vehicle, regardless of their mechanical connection to each other and to the vehicle frame or body. Thus, transverse pairs of wheels in an independent suspension may be called an axle in some contexts. This very loose definition of "axle"
4095-580: Is compatible with ergodic axioms. Logic was employed to some extent in Babylonian astronomy and medicine. Babylonian thought had a considerable influence on early Ancient Greek and Hellenistic philosophy . In particular, the Babylonian text Dialogue of Pessimism contains similarities to the agonistic thought of the Sophists , the Heraclitean doctrine of dialectic , and the dialogs of Plato , as well as
4212-592: Is dated within two standard deviations to 3340–3030 BCE, the axle to 3360–3045 BCE. Two types of early Neolithic European wheel and axle are known: a circumalpine type of wagon construction (the wheel and axle rotate together, as in Ljubljana Marshes Wheel), and that of the Baden culture in Hungary (axle does not rotate). They both are dated to c. 3200–3000 BCE. Some historians believe that there
4329-408: Is hollow, following the wheel at very close tolerances . 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
4446-591: Is indicator of one's future health. The Kalachakra or wheel of time is also a subject in some forms of Buddhism , along with the dharmachakra . The winged wheel is a symbol of progress, seen in many contexts including the coat of arms of Panama , the logo of the Ohio State Highway Patrol and the State Railway of Thailand . The wheel is also the prominent figure on the flag of India . The wheel in this case represents law ( dharma ). It also appears in
4563-445: Is known as " carbon steel ". The primary differences between the two are that chrome-moly steel is significantly more resistant to bending or breaking, and is very difficult to weld with tools normally found outside a professional welding shop. An axle that is driven by the engine or prime mover is called a drive axle . Modern front-wheel drive cars typically combine the transmission (gearbox and differential) and front axle into
4680-409: Is often used in assessing toll roads or vehicle taxes , and is taken as a rough proxy for the overall weight-bearing capacity of a vehicle, and its potential for causing wear or damage to roadway surfaces. Axles are an integral component of most practical wheeled vehicles. In a solid, "live-axle" suspension system, the rotating inner axle cores (or half-shafts) serve to transmit driving torque to
4797-550: Is thought that Nubian waterwheels may have been ox-driven. It is also known that Nubians used horse-drawn chariots imported from Egypt . Starting from the 18th century in West Africa, wheeled vehicles were mostly used for ceremonial purposes in places like Dahomey . The wheel was barely used for transportation, with the exception of Ethiopia and Somalia in Sub-Saharan Africa well into the 19th century. The spoked wheel
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4914-421: Is uncertain. The Babylonian development of methods for predicting the motions of the planets is considered to be a major episode in the history of astronomy . The only Greek-Babylonian astronomer known to have supported a heliocentric model of planetary motion was Seleucus of Seleucia (b. 190 BC). Seleucus is known from the writings of Plutarch . He supported Aristarchus of Samos' heliocentric theory where
5031-511: 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 , a pack animal, was not physically suited to use as a draft animal to pull wheeled vehicles, and use of the llama did not spread far beyond
5148-503: The Andes by the time of the arrival of Europeans. On the other hand, Mesoamericans never developed the wheelbarrow , the potter's wheel , nor any other practical object with a wheel or wheels. Although present in a number of toys, very similar to those found throughout the world and still made for children today ("pull toys"), the wheel was never put into practical use in Mesoamerica before
5265-663: The Earth rotated around its own axis which in turn revolved around the Sun . According to Plutarch , Seleucus even proved the heliocentric system, but it is not known what arguments he used, except that he correctly theorized on tides as a result of the Moon's attraction. Babylonian astronomy served as the basis for much of Greek , classical Indian , Sassanian, Byzantine , Syrian , medieval Islamic , Central Asian , and Western European astronomy. The oldest Babylonian texts on medicine date back to
5382-519: The Indus Valley civilization of the late 4th millennium BCE covering areas of present-day India and Pakistan . The oldest indirect evidence of wheeled movement was found in the form of miniature clay wheels north of the Black Sea before 4000 BCE. From the middle of the 4th millennium BCE onward, the evidence is condensed throughout Europe in the form of toy cars, depictions, or ruts, with
5499-599: The Jazira , is the area between the Euphrates and the Tigris from their sources down to Baghdad . Lower Mesopotamia is the area from Baghdad to the Persian Gulf and includes Kuwait and parts of western Iran. In modern academic usage, the term Mesopotamia often also has a chronological connotation. It is usually used to designate the area until the Muslim conquests , with names like Syria , Jazira , and Iraq being used to describe
5616-688: The Old Babylonian period in the first half of the 2nd millennium BC . The most extensive Babylonian medical text, however, is the Diagnostic Handbook written by the ummânū , or chief scholar, Esagil-kin-apli of Borsippa , during the reign of the Babylonian king Adad-apla-iddina (1069–1046 BC). Along with contemporary Egyptian medicine , the Babylonians introduced the concepts of diagnosis , prognosis , physical examination , enemas , and prescriptions . The Diagnostic Handbook introduced
5733-550: The Old English word hwēol , from Proto-Germanic * hwehwlaz , from Proto-Indo-European * kéklos , an extended form of the root * kel- ' to revolve, move around ' . Cognates within Indo-European include Icelandic hjól ' wheel, tyre ' , Greek κύκλος kúklos , and Sanskrit chakra , the last two both meaning ' circle ' or ' wheel ' . Archaeological artifacts demonstrate
5850-575: The flag of the Romani people , hinting to their nomadic history and their Indian origins. The introduction of spoked ( chariot ) wheels in the Middle Bronze Age appears to have carried somewhat of a prestige. The sun cross appears to have a significance in Bronze Age religion , replacing the earlier concept of a solar barge with the more 'modern' and technologically advanced solar chariot . The wheel
5967-438: The marketplaces . Songs were sung to children who passed them on to their children. Thus songs were passed on through many generations as an oral tradition until writing was more universal. These songs provided a means of passing on through the centuries highly important information about historical events. Hunting was popular among Assyrian kings. Boxing and wrestling feature frequently in art, and some form of polo
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#17328378139176084-420: The propeller , the jet engine , the flywheel ( gyroscope ) and the turbine . A wheeled vehicle requires much less work to move than simply dragging the same weight. The low resistance to motion is explained by the fact that the frictional work done is no longer at the surface that the vehicle is traversing, but in the bearings . In the simplest and oldest case the bearing is just a round hole through which
6201-407: The É , a temple dedicated to the goddess Inanna at Uruk, from a building labeled as Temple C by its excavators. The early logographic system of cuneiform script took many years to master. Thus, only a limited number of individuals were hired as scribes to be trained in its use. It was not until the widespread use of a syllabic script was adopted under Sargon's rule that significant portions of
6318-679: The (two) rivers") comes from the ancient Greek root words μέσος ( mesos , 'middle') and ποταμός ( potamos , 'river') and translates to '(land) between rivers', likely being a calque of the older Aramaic term, with the Aramaic term itself likely being a calque of the Akkadian birit narim . It is used throughout the Greek Septuagint ( c. 250 BC ) to translate the Hebrew and Aramaic equivalent Naharaim . An even earlier Greek usage of
6435-487: The 16th century. Possibly the closest the Mayas came to the utilitarian wheel is the spindle whorl , and some scholars believe that these toys were originally made with spindle whorls and spindle sticks as "wheels" and "axes". Aboriginal Australians traditionally used circular discs rolled along the ground for target practice. Nubians from after about 400 BCE used wheels for spinning pottery and as water wheels . It
6552-432: The 1st century BC and 3rd century AD, including Adiabene , Osroene , and Hatra . The regional toponym Mesopotamia ( / ˌ m ɛ s ə p ə ˈ t eɪ m i ə / , Ancient Greek : Μεσοποταμία '[land] between rivers'; Arabic : بِلَاد ٱلرَّافِدَيْن Bilād ar-Rāfidayn or بَيْن ٱلنَّهْرَيْن Bayn an-Nahrayn ; Persian : میانرودان miyân rudân ; Syriac : ܒܝܬ ܢܗܪ̈ܝܢ Beth Nahrain "(land) between
6669-597: The 4th millennium BCE in the Middle East. The oldest surviving example of a potter's wheel was thought to be one found in Ur (modern day Iraq ) dating to approximately 3100 BCE. However, a potter's wheel found in western Ukraine , of the Cucuteni–Trypillia culture , dates to the middle of the 5th millennium BCE which pre-dates the earliest use of the potter's wheel in Mesopotamia. Wheels of uncertain dates have been found in
6786-532: The 8,000-year-old remains of early farmers found at an ancient graveyard in Germany . They compared the genetic signatures to those of modern populations and found similarities with the DNA of people living in today's Turkey and Iraq . The earliest language written in Mesopotamia was Sumerian , an agglutinative language isolate . Along with Sumerian, Semitic languages were also spoken in early Mesopotamia. Subartuan ,
6903-560: 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 approximately 1500 BCE. Some argue that the primary obstacle to large-scale development of the wheel in the Americas was the absence of domesticated large animals that could be used to pull wheeled carriages. The closest relative of cattle present in Americas in pre-Columbian times,
7020-467: The Greek peninsula where they joined with the existing Mediterranean peoples to give rise, eventually, to classical Greece after the breaking of Minoan dominance and consolidations led by pre-classical Sparta and Athens . Celtic chariots introduced an iron rim around the wheel in the 1st millennium BCE. In China , wheel tracks dating to around 2200 BCE have been found at Pingliangtai,
7137-467: The Mesopotamian population became literate. Massive archives of texts were recovered from the archaeological contexts of Old Babylonian scribal schools, through which literacy was disseminated. Akkadian gradually replaced Sumerian as the spoken language of Mesopotamia somewhere around the turn of the 3rd and the 2nd millennium BC. The exact dating being a matter of debate. Sumerian continued to be used as
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#17328378139177254-464: The Tigris unite and empty into the Persian Gulf . The arid environment ranges from the northern areas of rain-fed agriculture to the south where irrigation of agriculture is essential. This irrigation is aided by a high water table and by melting snows from the high peaks of the northern Zagros Mountains and from the Armenian Highlands, the source of the Tigris and Euphrates Rivers that give
7371-606: The ancient history of lower Mesopotamia—commenced in the early-third millennium BC with cuneiform records of early dynastic kings. This entire history ends with either the arrival of the Achaemenid Empire in the late 6th century BC or with the Muslim conquest and the establishment of the Caliphate in the late 7th century AD, from which point the region came to be known as Iraq . In the long span of this period, Mesopotamia housed some of
7488-400: The axle is lifted off the ground to save wear on the tires and axle, and to increase traction in the remaining wheels, and to decrease fuel consumption. Lifting an axle also alleviates lateral scrubbing of the additional axle in very tight turns, allowing the vehicle to turn more readily. In some situations, the removal of pressure from the additional axle is necessary for the vehicle to complete
7605-399: The axle passes (a " plain bearing "). Even with a plain bearing, the frictional work is greatly reduced because: Example: Additional energy is lost from the wheel-to-road interface. This is termed rolling resistance which is predominantly a deformation loss. It 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
7722-426: The bearings, housings, and only a short section of the shaft itself, that also carries all radial loads. The full-floating design is typically used in most ¾- and 1-ton light trucks, medium-duty trucks, and heavy-duty trucks. The overall assembly can carry more weight than a semi-floating or non-floating axle assembly because the hubs have two bearings riding on a fixed spindle. A full-floating axle can be identified by
7839-410: The chances of the patient's recovery. Esagil-kin-apli discovered a variety of illnesses and diseases and described their symptoms in his Diagnostic Handbook . These include the symptoms for many varieties of epilepsy and related ailments along with their diagnosis and prognosis. Some treatments used were likely based off the known characteristics of the ingredients used. The others were based on
7956-696: The city of Eridu , the Akkadian kingdoms, the Third Dynasty of Ur , and the various Assyrian empires. Some of the important historical Mesopotamian leaders were Ur-Nammu (king of Ur), Sargon of Akkad (who established the Akkadian Empire), Hammurabi (who established the Old Babylonian state), Ashur-uballit I and Tiglath-Pileser I (who established the Assyrian Empire). Scientists analysed DNA from
8073-614: The cultural mix. Periodic breakdowns in the cultural system have occurred for a number of reasons. The demands for labor has from time to time led to population increases that push the limits of the ecological carrying capacity , and should a period of climatic instability ensue, collapsing central government and declining populations can occur. Alternatively, military vulnerability to invasion from marginal hill tribes or nomadic pastoralists has led to periods of trade collapse and neglect of irrigation systems. Equally, centripetal tendencies amongst city-states have meant that central authority over
8190-421: The cycles of the moon. They divided the year into two seasons: summer and winter. The origins of astronomy as well as astrology date from this time. During the 8th and 7th centuries BC, Babylonian astronomers developed a new approach to astronomy. They began studying philosophy dealing with the ideal nature of the early universe and began employing an internal logic within their predictive planetary systems. This
8307-445: The development of cursive script, mathematics , astronomy , and agriculture ". It is recognised as the cradle of some of the world's earliest civilizations. The Sumerians and Akkadians , each originating from different areas, dominated Mesopotamia from the beginning of recorded history ( c. 3100 BC ) to the fall of Babylon in 539 BC. The rise of empires, beginning with Sargon of Akkad around 2350 BC, characterized
8424-480: The early Bronze Age . This implies the passage of several wheel-less millennia after the invention of agriculture and of pottery , during the Aceramic Neolithic . The Halaf culture of 6500–5100 BCE is sometimes credited with the earliest depiction of a wheeled vehicle, but there is no evidence of Halafians using either wheeled vehicles or pottery wheels. Potter's wheels are thought to have been used in
8541-456: The early manufacturers was Zetterbergs, located in Östervåla, Sweden. Their brand was Zeta-lyften. The liftable tandem drive axle was invented in 1957 by the Finnish truck manufacturer Vanajan Autotehdas , a company sharing history with Sisu Auto . A full-floating axle carries the vehicle's weight on the axle casing, not the half-shafts; they serve only to transmit torque from the differential to
8658-532: The end of the Neo-Babylonian period. Old Aramaic , which had already become common in Mesopotamia, then became the official provincial administration language of first the Neo-Assyrian Empire , and then the Achaemenid Empire : the official lect is called Imperial Aramaic . Akkadian fell into disuse, but both it and Sumerian were still used in temples for some centuries. The last Akkadian texts date from
8775-508: The eventual engine, and many other factors. 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
8892-481: The front of many light trucks. An exception to this rule is the independent (rear) swing axle suspension, wherein the half-axles are also load-bearing suspension arms. Independent drive-trains still need differentials (or diffs), but without fixed axle-housing tubes attached. The diff may be attached to the vehicle frame or body, and/or be integrated with the transmission (or gearbox) in a combined transaxle unit. The axle (half-)shafts then transmit driving torque to
9009-504: The full-floating assembly has bearings on both the inside and outside of the wheel hub. The other difference is axle removal. To remove the semi-floating axle, the wheel must be removed first; if such an axle breaks, the wheel is most likely to come off the vehicle. The semi-floating design is found under most ½-ton and lighter trucks, as well as in SUVs and rear-wheel-drive passenger cars, usually being smaller or less expensive models. A benefit of
9126-469: The historical region of Mesopotamia also includes parts of present-day Iran , Turkey , Syria and Kuwait . Mesopotamia is the site of the earliest developments of the Neolithic Revolution from around 10,000 BC. It has been identified as having "inspired some of the most important developments in human history, including the invention of the wheel , the planting of the first cereal crops ,
9243-461: The inner end of the shafts and retained in/by recesses in the differential carrier side gears which are themselves retained by the differential pinion gear (or "spider gear") shaft. A true semi-floating axle assembly places no side loads on the axle housing tubes or axle shafts. Axles that are pressed into ball or tapered roller bearings, which are in turn retained in the axle housings with flanges, bolts, and nuts do not "float" and place axial loads on
9360-464: The invention of several types of wheel cover, which may be constructed as removable attachments or as permanent covers. Wheels like this are no longer necessarily round, or have panels that make the ground-contact area flat. Examples include: Truck and bus wheels may block (stop rotating) under certain circumstances, such as brake system failure. To help detect this, they sometimes feature "wheel rotation indicators": colored strips of plastic attached to
9477-460: The late 1st century AD. Early in Mesopotamia's history, around the mid-4th millennium BC, cuneiform was invented for the Sumerian language. Cuneiform literally means "wedge-shaped", due to the triangular tip of the stylus used for impressing signs on wet clay. The standardized form of each cuneiform sign appears to have been developed from pictograms . The earliest texts, 7 archaic tablets, come from
9594-412: The late 20th century. Cast alloy wheels are now more commonly used; forged alloy wheels are used when weight is critical. The invention of the wheel has also been important for technology in general, important applications including the water wheel , the cogwheel (see also antikythera mechanism ), the spinning wheel , and the astrolabe or torquetum . More modern descendants of the wheel include
9711-472: The methods of therapy and aetiology and the use of empiricism , logic , and rationality in diagnosis, prognosis and therapy. The text contains a list of medical symptoms and often detailed empirical observations along with logical rules used in combining observed symptoms on the body of a patient with its diagnosis and prognosis. The symptoms and diseases of a patient were treated through therapeutic means such as bandages , creams and pills . If
9828-568: The name Mesopotamia is evident from The Anabasis of Alexander , which was written in the late 2nd century AD but specifically refers to sources from the time of Alexander the Great . In the Anabasis , Mesopotamia was used to designate the land east of the Euphrates in north Syria . The Akkadian term biritum/birit narim corresponded to a similar geographical concept. Later, the term Mesopotamia
9945-720: The oldest find in Northern Germany dating back to around 3400 BCE. In Mesopotamia , depictions of wheeled wagons found on clay tablet pictographs at the Eanna district of Uruk , in the Sumerian civilization are dated to c. 3500–3350 BCE. In the second half of the 4th millennium BCE, evidence of wheeled vehicles appeared near-simultaneously in the Northern ( Maykop culture ) and South Caucasus and Eastern Europe ( Cucuteni-Trypillian culture ). Depictions of
10062-420: The origins of philosophy can be traced back to early Mesopotamian wisdom , which embodied certain philosophies of life, particularly ethics , in the forms of dialectic , dialogues , epic poetry , folklore , hymns , lyrics , prose works, and proverbs . Babylonian reason and rationality developed beyond empirical observation. Babylonian thought was also based on an open-systems ontology which
10179-402: The present day, allow accurate associations of relative with absolute dating for establishing the history of Mesopotamia. The Babylonian astronomers were very adept at mathematics and could predict eclipses and solstices . Scholars thought that everything had some purpose in astronomy. Most of these related to religion and omens. Mesopotamian astronomers worked out a 12-month calendar based on
10296-425: The region after that date. It has been argued that these later euphemisms are Eurocentric terms attributed to the region in the midst of various 19th-century Western encroachments. Mesopotamia encompasses the land between the Euphrates and Tigris rivers, both of which have their headwaters in the neighboring Armenian highlands . Both rivers are fed by numerous tributaries, and the entire river system drains
10413-801: The region coming under ephemeral Roman control. In 226 AD, the eastern regions of Mesopotamia fell to the Sassanid Persians . The division of the region between the Roman Byzantine Empire from 395 AD and the Sassanid Empire lasted until the 7th century Muslim conquest of Persia of the Sasanian Empire and the Muslim conquest of the Levant from the Byzantines. A number of primarily neo-Assyrian and Christian native Mesopotamian states existed between
10530-613: The region for a century as the final independent Mesopotamian realm until the modern era. In 539 BC, Mesopotamia was conquered by the Achaemenid Empire . The area was next conquered by Alexander the Great in 332 BC. After his death, it became part of the Greek Seleucid Empire . Around 150 BC, Mesopotamia was under the control of the Parthian Empire . It became a battleground between the Romans and Parthians, with western parts of
10647-441: The region its name. The usefulness of irrigation depends upon the ability to mobilize sufficient labor for the construction and maintenance of canals, and this, from the earliest period, has assisted the development of urban settlements and centralized systems of political authority. Agriculture throughout the region has been supplemented by nomadic pastoralism, where tent-dwelling nomads herded sheep and goats (and later camels) from
10764-429: The rim and protruding out from it, such that they can be seen by the driver in the side-view mirrors . These devices were invented and patented in 1998 by a Canadian truck shop owner. 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: The wheel has also become
10881-461: The river pastures in the dry summer months, out into seasonal grazing lands on the desert fringe in the wet winter season. The area is generally lacking in building stone, precious metals, and timber, and so historically has relied upon long-distance trade of agricultural products to secure these items from outlying areas. In the marshlands to the south of the area, a complex water-borne fishing culture has existed since prehistoric times and has added to
10998-438: The same as tensioned flexible wires, keeping the rim true while supporting applied loads. Wire wheels are used on most bicycles and still used on many motorcycles . They were invented by aeronautical engineer George Cayley and first used in bicycles by James Starley . A process of assembling wire wheels is described as wheelbuilding . A tire ( American English and Canadian English ) or tyre ( Commonwealth English )
11115-465: The subsequent 2,000 years of Mesopotamian history, marked by the succession of kingdoms and empires such as the Akkadian Empire . The early second millennium BC saw the polarization of Mesopotamian society into Assyria in the north and Babylonia in the south. From 900 to 612 BC, the Neo-Assyrian Empire asserted control over much of the ancient Near East. Subsequently, the Babylonians, who had long been overshadowed by Assyria, seized power , dominating
11232-534: The syllabary were all arranged and named, and elaborate lists were drawn up. Many Babylonian literary works are still studied today. One of the most famous of these was the Epic of Gilgamesh , in twelve books, translated from the original Sumerian by a certain Sîn-lēqi-unninni , and arranged upon an astronomical principle. Each division contains the story of a single adventure in the career of Gilgamesh . The whole story
11349-550: The symbolic qualities. Mesopotamian people invented many technologies including metal and copper-working, glass and lamp making, textile weaving, flood control , water storage, and irrigation. They were also one of the first Bronze Age societies in the world. They developed from copper, bronze, and gold on to iron. Palaces were decorated with hundreds of kilograms of these very expensive metals. Also, copper, bronze, and iron were used for armor as well as for different weapons such as swords, daggers, spears, and maces . According to
11466-415: The tire and tube. In the 1st millennium BCE an iron rim was introduced around the wooden wheels of chariots . The hub is the center of the wheel, and typically houses a bearing , 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 center hub . More specifically, the hub is actually almost as big as the wheel itself. The axle
11583-458: The two half-axles and the differential constitute the rear axle. The front drive axle is providing the force to drive the truck. In fact, only one wheel of that axle is actually moving the truck and trailer down the road. Some simple vehicle designs, such as leisure go-karts, may have a single driven wheel where the drive axle is a split axle with only one of the two shafts driven by the engine, or else have both wheels connected to one shaft without
11700-418: The volume of the frustum of a cone or a square pyramid was incorrectly taken as the product of the height and half the sum of the bases. Also, there was a recent discovery in which a tablet used π as 25/8 (3.125 instead of 3.14159~). The Babylonians are also known for the Babylonian mile, which was a measure of distance equal to about seven modern miles (11 km). This measurement for distances eventually
11817-417: The wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a spindle . On cars and trucks, several senses of the word axle occur in casual usage, referring to the shaft itself, its housing, or simply any transverse pair of wheels. Strictly speaking, a shaft that rotates with the wheel, being either bolted or splined in fixed relation to it,
11934-400: The wheel positions steady under heavy stress, and can therefore support heavy loads. Straight axles are used on trains (that is, locomotives and railway wagons), for the rear axles of commercial trucks, and on heavy-duty off-road vehicles. The axle can optionally be protected and further reinforced by enclosing the length of the axle in a housing. In split-axle designs, the wheel on each side
12051-456: The wheels at each end, while the rigid outer tube maintains the position of the wheels at fixed angles relative to the axle, and controls the angle of the axle and wheels assembly to the vehicle body. The solid axles (housings) in this system must also bear the weight of the vehicle plus any cargo. A non-driving axle, such as the front beam axle in heavy-duty trucks and some two-wheel drive light trucks and vans, will have no shaft, and serves only as
12168-403: The wheels, usually via constant-velocity joints . Like a full floating axle system, the drive shafts in a front-wheel-drive independent suspension system do not support any vehicle weight. A straight axle is a single rigid shaft connecting a wheel on the left side of the vehicle to a wheel on the right side. The axis of rotation fixed by the axle is common to both wheels. Such a design can keep
12285-400: The wheels. They "float" inside an assembly that carries the vehicle's weight. Thus the only stress it must endure is torque (not lateral bending force). Full-floating axle shafts are retained by a flange bolted to the hub , while the hub and bearings are retained on the spindle by a large nut. In contrast, a semi-floating design carries the weight of the vehicle on the axle shaft itself; there
12402-679: The whole region, when imposed, has tended to be ephemeral, and localism has fragmented power into tribal or smaller regional units. These trends have continued to the present day in Iraq. The prehistory of the Ancient Near East begins in the Lower Paleolithic period. Therein, writing emerged with a pictographic script, Proto-cuneiform , in the Uruk IV period ( c. late 4th millennium BC ). The documented record of actual historical events—and
12519-724: The world's most ancient highly developed, and socially complex states. The region was one of the four riverine civilizations where writing was invented, along with the Nile valley in Ancient Egypt , the Indus Valley civilization in the Indian subcontinent , and the Yellow River in Ancient China . Mesopotamia housed historically important cities such as Uruk , Nippur , Nineveh , Assur and Babylon , as well as major territorial states such as
12636-501: Was a diffusion of the wheeled vehicle from the Near East to Europe around the mid-4th millennium BCE. 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
12753-590: Was also a solar symbol for the Ancient Egyptians . In modern usage, the 'invention of the wheel' can be considered as a symbol of one of the first technologies of early civilization, alongside farming and metalwork, and thus be used as a benchmark to grade the level of societal progress. Some Neopagans such as Wiccans have adopted the Wheel of the Year into their religious practices. Axle An axle or axletree
12870-430: Was an important contribution to astronomy and the philosophy of science and some scholars have thus referred to this new approach as the first scientific revolution. This new approach to astronomy was adopted and further developed in Greek and Hellenistic astronomy. In Seleucid and Parthian times, the astronomical reports were thoroughly scientific. How much earlier their advanced knowledge and methods were developed
12987-497: Was converted to a time-mile used for measuring the travel of the Sun, therefore, representing time. The roots of algebra can be traced to the ancient Babylonia who developed an advanced arithmetical system with which they were able to do calculations in an algorithmic fashion. The Babylonian clay tablet YBC 7289 ( c. 1800 –1600 BC) gives an approximation of √ 2 in four sexagesimal figures, 1 24 51 10 , which
13104-428: Was in continued use without major modification until the 1870s, when wire-spoked wheels and pneumatic tires were invented. Pneumatic tires can greatly reduce rolling resistance and improve comfort. Wire spokes are under tension, not compression, making it possible for the wheel to be both stiff and light. Early radially-spoked wire wheels gave rise to tangentially-spoked wire wheels, which were widely used on cars into
13221-412: Was instrumental in early map-making . The Babylonians also had theorems on how to measure the area of several shapes and solids. They measured the circumference of a circle as three times the diameter and the area as one-twelfth the square of the circumference, which would be correct if π were fixed at 3. The volume of a cylinder was taken as the product of the area of the base and the height; however,
13338-504: Was invented more recently and allowed the construction of lighter and swifter vehicles. The earliest known examples of wooden spoked wheels are in the context of the Sintashta culture , dating to c. 2000 BCE ( Krivoye Lake ). Soon after this, horse cultures of the Caucasus region used horse-drawn spoked-wheel war chariots for the greater part of three centuries. They moved deep into
13455-618: Was more generally applied to all the lands between the Euphrates and the Tigris , thereby incorporating not only parts of Syria but also almost all of Iraq and southeastern Turkey . The neighbouring steppes to the west of the Euphrates and the western part of the Zagros Mountains are also often included under the wider term Mesopotamia . A further distinction is usually made between Northern or Upper Mesopotamia and Southern or Lower Mesopotamia . Upper Mesopotamia, also known as
13572-450: Was the first recorded. Mesopotamians believed that the world was a flat disc, surrounded by a huge, holed space, and above that, heaven . They believed that water was everywhere, the top, bottom and sides, and that the universe was born from this enormous sea. Mesopotamian religion was polytheistic . Although the beliefs described above were held in common among Mesopotamians, there were regional variations. The Sumerian word for universe
13689-646: Was uncovered at the Must Farm site in East Anglia in 2016. The specimen, dating from 1,100 to 800 BCE, represents the most complete and earliest of its type found in Britain. The wheel's hub is also present. A horse's spine found nearby suggests the wheel may have been part of a horse-drawn cart. The wheel was found in a settlement built on stilts over wetland, indicating that the settlement had some sort of link to dry land. Although large-scale use of wheels did not occur in
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