Through dc regenerative braking, ac variablespeed braking, and ac servo braking are growing, friction devices, especially in small industrial applications, aren’t going anywhere ...

Sometimes though, friction can be a nuisance. For example, the friction between a wheel and the axle that it rotates on wastes energy, so we try to minimise the friction using bearings and lubricants.

Friction is responsible for about twenty percent of the world energy consumption. The main reason for this is that frictional forces slow down the motion of surfaces in contact: think of the ...