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 or tyre 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.
Continuous track or tracked treads are a system of vehicle propulsion used in tracked vehicles, running on a continuous band of treads or track plates driven by two or more wheels. The large surface area of the tracks distributes the weight of the vehicle better than steel or rubber tyres on an equivalent vehicle, enabling continuous tracked vehicles to traverse soft ground with less likelihood of becoming stuck due to sinking.
An axle or axletree 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 the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a spindle.
A four-wheel drive, also called 4×4 or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges.
An off-road vehicle (ORV), sometimes referred to as an off-highway vehicle (OHV), overland vehicle, or adventure vehicle, is considered to be any type of vehicle that is capable of driving off paved or gravel surfaces, such as trails and forest roads that have rough and low traction surfaces.
A cyclo-cross bike or cyclo-cross bicycle is a bicycle specifically designed for the rigors of a cyclo-cross race. Cyclo-cross bicycles roughly resemble the racing bicycles used in road racing. The major differences between the two are the frame geometry, and the wider clearances that cyclo-cross bikes have for their larger tires and mud and other debris that they accumulate.
A locking differential is a mechanical component, commonly used in vehicles, designed to overcome the chief limitation of a standard open differential by essentially "locking" both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction available to either wheel individually.
The wheel size for a motor vehicle or similar wheel has a number of parameters.
Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or other wheeled vehicle occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction that prevents the vehicle from responding to control inputs. If it occurs to all wheels simultaneously, the vehicle becomes, in effect, an uncontrolled sled. Aquaplaning is a different phenomenon from when water on the surface of the roadway merely acts as a lubricant. Traction is diminished on wet pavement even when aquaplaning is not occurring.
A de Dion tube is a form of non-independent automobile suspension. It is a considerable improvement over the swing axle, Hotchkiss drive, or live axle. Because it plays no part in transmitting power to the drive wheels, it is sometimes called a "dead axle".
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation of the wheel, roadbed, etc., is recovered when the pressure is removed. Two forms of this are hysteresis losses, and permanent (plastic) deformation of the object or the surface. Note that the slippage between the wheel and the surface also results in energy dissipation. Although some researchers have included this term in rolling resistance, some suggest that this dissipation term should be treated separately from rolling resistance because it is due to the applied torque to the wheel and the resultant slip between the wheel and ground, which is called slip loss or slip resistance. In addition, only the so-called slip resistance involves friction, therefore the name "rolling friction" is to an extent a misnomer.
A beadlock or bead lock is a mechanical device that secures the bead of a tire to the wheel of a vehicle. Tires and wheels are designed so that when the tire is inflated, the tire pressure pushes the bead of the tire against the inside of the wheel rim so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
A beam axle, rigid axle or solid axle is a dependent suspension design in which a set of wheels is connected laterally by a single beam or shaft. Beam axles were once commonly used at the rear wheels of a vehicle, but historically they have also been used as front axles in four-wheel-drive vehicles. In most automobiles, beam axles have been replaced with front (IFS) and rear independent suspensions (IRS).
A wheelspin occurs when the force delivered to the tire tread exceeds that of available tread-to-surface friction and one or more tires lose traction. This leads the wheels to "spin" and causes the driver to lose control over the tires that no longer have grip on the road surface. Wheelspin can also be done intentionally such as in drifting or doing a burnout.
Snow tires, also known as winter tires, are tires designed for use on snow and ice. Snow tires have a tread design with larger gaps than those on conventional tires, increasing traction on snow and ice. Such tires that have passed specific winter traction performance tests are entitled to display a 3PMSF and/or a IMP symbols on their sidewalls. Tires designed for winter conditions are optimized to drive at temperatures below 7 °C (45 °F). Studded tires are a type of snow tires which have metal or ceramic studs that protrude from the tire to increase traction on hard-packed snow or ice. Studs abrade dry pavement, causing dust and creating wear in the wheel path. Regulations that require the use of snow tires or permit the use of studs vary by country in Asia and Europe, and by state or province in North America.
Roths Industries, Inc. (1945–1960) was a manufacturer of small garden tractors and other agricultural equipment founded by Herbert C. Roths in Alma, Michigan. The company manufactured Garden King Walking Tractors, BesRo Riding Tractors, and Till Ro Stalk Cutters.
Grousers are devices intended to increase the traction of continuous tracks, especially in loose material such as soil or snow. This is done by increasing contact with the ground with protrusions, similar to conventional tire treads, and analogous to athletes' cleated shoes. On tanks and armoured vehicles, grousers are usually pads attached to the tracks; but on construction vehicles they may take the form of flat plates or bars.
Snow socks are textile alternatives to snow chains. Snow sock devices wrap around the tires of a vehicle to increase traction on snow and ice. Snow socks are normally composed of a woven fabric with an elastomer attached to the inner and/or outer edge. The woven fabric covers the tire tread and is the contact point between the vehicle and the road. The elastomer keeps the snow sock in place and facilitates with installation. Some snow sock models have an additional component that covers the rim of the tire, which prevents snow or debris from gathering between the tread of the tire and the inner side of the woven fabric.
Bar grip tyres, or 'NDT' in US military parlance, are an early tyre tread pattern developed for off-road use.
