Complex machines are so a part of everyday life, it is easy to forget that they work effectively in a very simple principle. Using simple as a lever and wheel to increase or redirect the force of our muscles, we can work it would be impossible with our bare hands. In everyday life we use a wide range of machinery, cranes, giant quicksand escalator even humble bicycle. But all machines, regardless of their complexity, the use of basic principles of simple machines, especially the leverage. Lever can act not only in straight lines, but can not multiply forces in turn.

For example, in a wind turbine rotor harness wind energy and transfer it to a central axis (shaft). Although the axle rotates in the same angle as the end of the rotor blade, it moves much smaller distance. This means that a relatively small force of the wind, as insisted by the end of the blade through a large distance is translated into a much stronger factor in the axis. Power in the axis, which came a puff of wind can be used to turn a generator.