Tires are mounted to wheels that bolt to the hub. The beads of the tire are held on the wheel's rim largely by the internal tire force from the air pressure. Automotive wheels are typically made from pressed and welded steel, or a composite of lightweight metal alloys, such as aluminum or magnesium.

These alloy wheels may be either cast or forged. A decorative hubcap and trim ring may be placed over the wheel.

A wheel is a circular device that is capable of rotating on an axle through its center, facilitating movement or transportation while supporting a load (mass), or performing labor in machines. Common examples are found in transport applications. A wheel, together with an axle, overcomes friction by facilitating motion by rolling. 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 application of another external force. More generally the term is also used for other circular objects that rotate or turn, such as a ship's wheel, steering wheel and flywheel.

The wheel is a device that enables efficient movement of an object across a surface where there is a force pressing the object to the surface. Common examples are a cart pulled by a horse, and the rollers on an aircraft flap mechanism.

Wheels are used in conjunction with axles, either the wheel turns on the axle, or the axle turns in the object body. The mechanics are the same in either case.
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.

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. Note that wheels pre-date driven wheels by about 6000 years.

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