A wheel is a circular device that is capable of rotating on an axle through its centre, facilitating movement or transportation while supporting a load, or performing labour 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...