Rim (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. The term rim is also used non-technically to refer to the entire wheel, or even to a tire. In the 1st millennium BC, an iron rim was introduced around the wooden wheels of chariots. Cross section of a bicycle rim wooden bicycle rim with tubular tyre Characteristics Scratched rim on two-piece wheel. Black residue remaining from where the tire was seated on the "safety profile" rim. Diameter (effective): distance between the bead seats (for the tire), as measured in the plane of the rim and through the axis of the hub which is or will be attached, or which is integral with the rim. Width (effective): separation distance between opposed rim flanges. The flange-to-flange width of a rim should be a minimum of three-quarters of the tire section width. And the maximum rim width should be equal to the width of the tire tread. Type: Depends on the type of vehicle and tire. There are various rim profiles, as well as the number of rim components.   Thomas B. Jeffery's 1882 clincher rim patent Modern passenger vehicles and tubeless tires typically use one-piece rims with a "safety" rim profile. The safety feature helps keep the tire bead held to the rim under adverse conditions by having a pair of safety humps extending inwardly of the rim toward the other tire bead seat from an outer contoured surface of the rim. Heavy vehicles and some trucks may have a removable multi-piece rim assembly consisting of a base that mounts to the wheel and axle. They then have either a side ring or a side and lock ring combination. These parts are removable from one side for tire mounting, while the opposite side attached to the base has a fixed flange. Material: Various metals can be used for the rim. Commonly seen are alloy (magnesium and aluminum), mag (magnesium), aluminum, and chrome. Teflon coatings are sometimes also applied for an extra layer of protection. Vehicle performance: Because the rim is where the tire resides on the wheel and the rim supports the tire shape, the dimensions of the rims are a factor in the handling characteristics of an automobile. For example: Overly wide rims in relation...

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Magnesium wheels

Magnesium wheels are wheels manufactured from alloys which contain mostly magnesium. Magnesium wheels are produced either by casting (metalworking) (where molten metal is introduced into a mold, solidifying within the mold), or by forging (where a prefabricated bar is deformed mechanically). Magnesium has several key properties that make it an attractive base metal for wheels: lightness; a high damping capacity; and a high specific strength. Magnesium is the lightest metallic structural material available. It is 1.5 times less dense than aluminium, so magnesium wheels can be designed to be significantly lighter than aluminium alloy wheels, while exhibiting comparable strength. All competitive racing rims are now made of magnesium alloy. Cast magnesium wheels Taking into account their generally inferior quality compared to forged wheels, the main advantage of cast wheels is the relatively low cost of production. And although cast wheels are more affordable than forged wheels, cast wheels are heavier than forged wheels for a given required load. Manufacturing defects found in cast wheels include cavities or porosity and a different metallurgical microstructure, entailing larger grain size. Cast wheels will tend to fracture upon overbearing high-speed impact, whereas forged wheels will tend to bend. Forged magnesium wheels Forged magnesium wheels are manufactured by mechanically deforming (forging) a prefabricated rod using a powerful forging press. Several somewhat different forging techniques exist, all of them comprising a multi-step process/operation. The resultant forging is subsequently machined (lathe-turned and milled) into the final shape of a wheel by removing excess metal from the forged blank. A forged magnesium wheel is 25 percent lighter than cast wheel. The main disadvantage of forged wheels is the high manufacturing cost. And due to the typically high costs of finished wheels, forged wheels are still rarely purchased by non-professional drivers for regular road use. But since forged wheels can be designed to be lighter than cast wheels for a given load, forged wheels do offer fuel economy and other distinct advantages. The forging process allows alignment of the metal fibers and optimization of the directional pattern arrangement along the spokes of a wheel. This, along with the smaller grain size, results in superior mechanical properties and performance characteristics that make forged magnesium wheels widely popular both for motor racing and with knowledgeable driving enthusiasts. History The original cast magnesium wheels were made beginning in the 1930s and their production continues today. Some of the biggest brands producing magnesium wheels in the past include Halibrand, American Racing, Campagnolo, Cromodora, Ronal, Technomagnesio, and Watanabe. The popularity of magnesium...

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Tweel

The Tweel (a portmanteau of tire and wheel) is an airless tire design concept developed by the French tire company Michelin. Its significant advantage over pneumatic tires is that the Tweel does not use a bladder full of compressed air, and therefore it cannot burst, leak pressure, or become flat. Instead, the Tweel assembly's inner hub connects to flexible polyurethane spokes which are used to support an outer rim and these engineered compliant components assume the shock-absorbing role provided by the compressed air in a traditional tire. The Tweel airless tire design Design The Tweel consists of a band of conventional tire rubber with molded tread, a shear beam just below the tread that creates a compliant contact patch, a series of energy-absorbing polyurethane spokes, and an integral inner rim structure. Both the shear beam and the polyurethane spokes can be designed to provide a calibrated directional stiffness in order that design engineers are able to control both how the Tweel handles and how it handles loads. The inner hub structure may be either rigid or compliant, depending on the application requirements, and as such may contain a matrix of deformable plastic structures that flex under load and subsequently return to their original shape. By varying the thickness and size of the spokes, Michelin can manipulate the design elements to engineer a wide array of ride and handling qualities. The tread can be as specialized as any of today's tires and is replaceable when worn. Benefits and drawbacks Potential benefits of the Tweel include not only the obvious safety and convenience of never having flat tires, but also, in automotive applications, the Tweel airless tire has the potential to be able to brake better - a significant performance compromise that is inherent to pneumatic tires. Unlike a pneumatic tire, a Tweel can be designed to have high lateral stiffness while simultaneously having low vertical stiffness. This can be achieved because, in the design elements of a Tweel, the vertical and lateral stiffness are not inseparably linked and can thus be optimized independently. Because there is no air bladder under the tread, tread patterns can, if desired, even incorporate water evacuation through holes in the design thus eliminating or significantly reducing hydroplaning. Michelin expects the tread to last two to three times as long as a conventional tire. Because the tread rubber around the outer circumference is replaceable when worn (as opposed to disposing of a whole worn tire), the potential environmental impact of a Tweel airless tire can be less than that of a conventional pneumatic tire. Tweel...

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Artillery wheel

The artillery wheel was developed for use on gun carriages when it was found that the lateral forces involved in horse artillery manoeuvres caused normally constructed cart wheels to collapse. Rather than having its spokes mortised into a wooden nave (hub), it has them fitted together (mitred) then bolted into a metal nave. Its tyre is shrunk onto the rim in the usual way but it is also bolted on for security. A normal wagon wheel is dished so that in its lowest part, the spokes are perpendicular to the ground thus supporting the weight (with the axle not truly horizontal but angled downward toward the outside about 5 degrees). This is not done with artillery wheels.    Artillery wheel Motor vehicles 1927 Ford T with artillery wheels When higher speeds and consequently higher lateral forces were attained with the introduction of motor vehicles, the artillery wheel was used in those too. By the 1920s, motor cars used wheels that looked at a glance like artillery wheels but which were of forged steel or welded from steel pressed sections. These too were usually called artillery wheels. Joseph Sankey's pressed steel artillery wheels 1908 aftermarket pressed and welded detachable steel wheel on a 1907 Austin After training as an engineer, Joseph Sankey founded a major tea tray producer. A pioneer motorist, Sankey became personal friends with Herbert Austin, becoming a supplier of sheet steel components to the industry as a result. By 1914, Joseph Sankey and Sons Ltd. supplied sheet steel bodies to Austin, Daimler, Humber, Rover, Star and Argyll. As a result of complaints from motor manufacturers about the wooden wheels on these early cars disintegrating upon touching any roadside kerb, In 1908 Sankey with his works manager, Wingfield Burton, developed and patented the first pressed-steel and welded detachable motor car wheel. Production started in 1908, with customers including Herbert Austin and, later, William Morris. In addition to his original factory at Bilston a new plant was established near Wellington, Shropshire, which was devoted to wheel production. In 1920, GKN purchased steel company John Lysaght and their subsidiary, Joseph Sankey and Sons Ltd. By that time the plant was supplying wheels to many UK manufacturers. Wire wheels By the late 1920s the inadequacies of artillery wheels had brought about their sweeping replacement by the more expensive wire wheels. References a b c d e f g h "Making the most of it Or – are you driving a GKN?". Motor. 10 May 1969. pp. 58–60. Edgar Jones, A History of GKN: Volume 2: The Growth of a Business, 1918-1945, Macmillan, London, 1990 ISBN 9781349096664

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Alloy wheel

In the automotive industry, alloy wheels are wheels that are made from an alloy of aluminium or magnesium. Alloys are mixtures of a metal and other elements. They generally provide greater strength over pure metals, which are usually much softer and more ductile. Alloys of aluminium or magnesium are typically lighter for the same strength, provide better heat conduction, and often produce improved cosmetic appearance over steel wheels. Although steel, the most common material used in wheel production, is an alloy of iron and carbon, the term "alloy wheel" is usually reserved for wheels made from nonferrous alloys. The earliest light-alloy wheels were made of magnesium alloys. Although they lost favor on common vehicles, they remained popular through the 1960s, albeit in very limited numbers. In the mid-to-late 1960s, aluminum-casting refinements allowed the manufacture of safer wheels that were not as brittle. Until this time, most aluminum wheels suffered from low ductility, usually ranging from 2-3% elongation. Because light-alloy wheels at the time were often made of magnesium (often referred to as "mags"), these early wheel failures were later attributed to magnesium's low ductility, when in many instances these wheels were poorly cast aluminum alloy wheels. Once these aluminum castingimprovements were more widely adopted, the aluminum wheel took the place of magnesium as low cost, high-performance wheels for motorsports. Alloy wheel on a passenger car Characteristics Alcoa's heavy-duty alloy wheel, for buses and trucks. Lighter wheels can improve handling by reducing unsprung mass, allowing suspension to follow the terrain more closely and thus improve grip, however not all alloy wheels are lighter than their steel equivalents. Reduction in overall vehicle mass can also help to reduce fuel consumption. Better heat conduction and a more open wheel design can help dissipate heat from the brakes, which improves braking performance in more demanding driving conditions and reduces the chance of diminished brake performance or even failure due to overheating. An aluminum alloy wheel designed to recall the crossed spokes of a wire wheel Alloy wheels are also purchased for cosmetic purposes although the cheaper alloys used are usually not corrosion-resistant. Alloys allow the use of attractive bare-metal finishes, but these need to be sealed with paint or wheel covers. Even if so protected the wheels in use will eventually start to corrode after 3 to 5 years but refurbishment is now widely available at a cost. The manufacturing processes also allow intricate, bold designs. In contrast, steel wheels are usually pressed from sheet metal, and then welded together (often leaving unsightly bumps) and must be painted to avoid corrosion and/or hidden with wheel covers/hub caps. Alloy wheels are prone to galvanic corrosion, which...

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Wheel

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. Three wheels on an antique tricycle The earliest wheels were made of a solid piece of wood. Etymology The English word wheel comes from the Old English word hweol, hweogol, from Proto-Germanic *hwehwlan, *hwegwlan, from Proto-Indo-European *kwekwlo-, an extended form of the root *kwel- "to revolve, move around". Cognates within Indo-European include Icelandic hjól "wheel, tyre", Greek κύκλος kúklos, and Sanskrit chakra, the latter two both meaning "circle" or "wheel". History The invention of the wheel falls into the late Neolithic, and may be seen in conjunction with other technological advances that gave rise to the early Bronze Age. This implies the passage of several wheel-less millennia even after the invention of agriculture and of pottery, during the Aceramic Neolithic. 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 Bronze Age 2200–1550 BCE: Middle Bronze Age, invention of the spoked wheel and the chariot A depiction of an onager-drawn cart on the Sumerian "battle standard of Ur" (c. 2500 BC) The Halaf culture of 6500–5100 BCE is sometimes credited with the earliest depiction of a wheeled vehicle, but this is doubtful as there is no evidence of Halafians using either wheeled vehicles or even pottery wheels. Precursors of wheels, known as "tournettes" or "slow wheels", were known in the Middle East by the 5th millennium BCE (one of the earliest examples was discovered at Tepe Pardis, Iran, and dated to 5200–4700 BCE). These were made of stone or clay and secured to the ground with a peg in the center, but required significant effort to turn. True (freely-spinning) potter's wheels were apparently in use in Mesopotamia by 3500 BCE and possibly as early as 4000 BCE, and the oldest surviving example, which was found in Ur (modern day Iraq), dates to approximately 3100 BCE. The first evidence of wheeled vehicles appears in the second...

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