A wheel is a rotating component 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 a ship's wheel, steering wheel, potter's wheel, and flywheel.
A tire is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
A spoke is one of some number of rods radiating from the center of a wheel, connecting the hub with the round traction surface.
A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels.
A hubcap or hub cap is a decorative disk on an automobile wheel that covers at minimum the central portion of the wheel, called the hub. An automobile hubcap is used to cover the wheel hub and the wheel fasteners to reduce the accumulation of dirt and moisture. It also has the function of decorating the car.
A ship's wheel or boat's wheel is a device used aboard a water vessel or airship, in which a helmsman steers the vessel and control its course. Together with the rest of the steering mechanism, it forms part of the helm. It is connected to a mechanical, electric servo, or hydraulic system which alters the horizontal angle of the vessel's rudder relative to its hull. In some modern ships the wheel is replaced with a simple toggle that remotely controls an electro-mechanical or electro-hydraulic drive for the rudder, with a rudder position indicator presenting feedback to the helmsman.
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 cross-section, the rim is deep in the center and shallow at the outer edges, thus forming a "U" shape that supports the bead of the tire casing.
The artillery wheel was a nineteenth-century and early-twentieth-century style of wagon, gun carriage, and automobile wheel. Rather than having its spokes mortised into a wooden nave (hub), it has them fitted together in a keystone fashion with miter joints, bolted into a two-piece metal nave. Its tyre is shrunk onto the rim in the usual way, but it may also be bolted on for security.
An ox-wagon or bullock wagon is a four-wheeled vehicle pulled by oxen. It was a traditional form of transport, especially in Southern Africa but also in New Zealand and Australia. Ox-wagons were also used in the United States. The first recorded use of an ox-wagon was around 1670, but they continue to be used in some areas up to modern times.
Wire wheels, wire-spoked wheels, tension-spoked wheels, or "suspension" wheels are wheels whose rims connect to their hubs by wire spokes. Although these wires are considerably stiffer than a similar diameter wire rope, they function mechanically the same as tensioned flexible wires, keeping the rim true while supporting applied loads. The term suspension wheel should not be confused with vehicle suspension.
Shrink-fitting is a technique in which an interference fit is achieved by a relative size change after assembly. This is usually achieved by heating or cooling one component before assembly and allowing it to return to the ambient temperature after assembly, employing the phenomenon of thermal expansion to make a joint. For example, the thermal expansion of a piece of a metallic drainpipe allows a builder to fit the cooler piece to it. As the adjoined pieces reach the same temperature, the joint becomes strained and stronger.
The Mansell Wheel is a railway wheel patented by Richard Mansell, the Carriage and Wagon superintendent of the South Eastern Railway in the UK. The design was created in the 1840s and was eventually used widely on passenger railway stock in the UK. It is an interesting example of a composite wooden wheel, using the same principle as an artillery wheel but with a solid wooden centre instead of spokes. The drawing (right) is from a railway design book of the early 20th century.
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 steel wheel of a steam locomotive and other older types of rolling stock were usually fitted with a steel tire or tyre to provide a replaceable wearing element on a costly wheel.
A marathon carriage is a modern metal carriage that is used for driving competitions, especially combined driving. It is named after the cross-country phase of a combined driving event which, though inaccurate, became known as the "marathon" phase. The carriage is designed for safety and carries a driver plus one or two assistants, called grooms. Drivers direct the horses while grooms counterbalance the carriage on tight turns, and are available for assistance with the horses in case of an overturn or collision, or equipment malfunction.
A train wheel or rail wheel is a type of wheel specially designed for use on railway tracks. The wheel acts as a rolling component, typically press fitted onto an axle and mounted directly on a railway carriage or locomotive, or indirectly on a bogie, also called a truck. The powered wheels under the locomotive are called driving wheels. Wheels are initially cast or forged and then heat-treated to have a specific hardness. New wheels are machined using a lathe to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper interaction between the wheel and the rail. Incorrectly profiled wheels and worn wheels can increase rolling resistance, reduce energy efficiency and may even cause a derailment. The International Union of Railways has defined a standard wheel diameter of 920 mm (36 in), although smaller sizes are used in some rapid transit railway systems and on ro-ro carriages.
Motorcyclewheels are made to cope with radial and axial forces. They also provide a way of mounting other critical components such as the brakes, final drive and suspension. Wheels, and anything directly connected to them, are considered to be unsprung mass. Traditionally motorcycles used wire-spoked wheels with inner tubes and pneumatic tyres. Although cast wheels were first used on a motorcycle in 1927, it would not be until the 1970s that mainstream manufacturers would start to introduce cast wheels on their roadgoing motorcycles. Spoked wheels are usually made using steel spokes with steel or aluminium rims. Cast wheels are predominantly made from an aluminium-alloy, but can also be made from more-exotic materials, such as magnesium content alloy or carbon fibre.
Paper car wheels were composite wheels of railway carriages, made from a wrought iron or steel rim bolted to an iron hub with an interlayer of laminated paper. The center was made of compressed paper held between two plate-iron disks. Their ability to dampen rail/wheel noise resulted in a quiet and smooth ride for the passengers of North American Pullman dining and sleeping cars.
A tyring platform or tyring plate is a circular metal or stone table used for the fitting of a metal tyre or rim to a wooden wheel. These were commonplace when such wheels were needed for the numerous carts, carriages and wagons used throughout society and were standard equipment for a wheelwright.
