Wheel - Mechanics and Function

Mechanics and Function

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.

Bearings are used to help reduce friction at the interface. In the simplest and oldest case the bearing is just a round hole through which the axle passes (a "plain bearing").

Example:

  • If a 100 kg object is dragged for 10 m along a surface with the coefficient of friction μ = 0.5, the normal force is 981 N and the work done (required energy) is (work=force x distance) 981 × 0.5 × 10 = 4905 joules.
  • Now give the object 4 wheels. The normal force between the 4 wheels and axles is the same (in total) 981 N. Assume, for wood, μ = 0.25, and say the wheel diameter is 1000 mm and axle diameter is 50 mm. So while the object still moves 10 m the sliding frictional surfaces only slide over each other a distance of 0.5 m. The work done is 981 × 0.25 × 0.5 = 123 joules; the work done has reduced to 1/40 of that of dragging.

Additional energy is lost from the wheel-to-road interface. This is termed rolling resistance which is predominantly a deformation loss.

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

Read more about this topic:  Wheel

Other articles related to "mechanics, mechanics and, mechanics and function":

Invariance Mechanics - Constraints - History
... The history of invariance mechanics is difficult to pinpoint since many people have been working on it without realizing that they were working on invariance ... demonstrated the connection between invariance mechanics and loop quantum gravity ...
Mechanics - Professional Organizations
... Applied Mechanics Division, American Society of Mechanical Engineers Fluid Dynamics Division, American Physical Society Institution of Mechanical Engineers is the United Kingdom's qualifying body for ... International Union of Theoretical and Applied Mechanics ...
John W. Hutchinson
... April 10, 1939) is a renowned scholar in the field of applied mechanics, and has made seminal contributions to the mechanics of structures and mechanics of materials ... been the author of very important and famous works about solid and fracture mechanics, among the others the so called HRR (Hutchinson-Rice-Rosengren) theory of elastic-plastic ...
Offset (wheel) - Mechanics and Function
... 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 ...

Famous quotes containing the words function and/or mechanics:

    The fact remains that the human being in early childhood learns to consider one or the other aspect of bodily function as evil, shameful, or unsafe. There is not a culture which does not use a combination of these devils to develop, by way of counterpoint, its own style of faith, pride, certainty, and initiative.
    Erik H. Erikson (1904–1994)

    It is only the impossible that is possible for God. He has given over the possible to the mechanics of matter and the autonomy of his creatures.
    Simone Weil (1909–1943)