The actual mechanical advantage in the loading ramp example is about 3.6 with wheels and about 1.4 without wheels. Simple Machines Simple machines are the most basic devices that can modify the effort required to accomplish work. Inclined planes and their principle of operation can be found in a broad range of applications such as roads, loading ramps, and escalators. They are also the basis of two other simple machines, the screw and the wedge. A wedge is often the shape of two inclined planes placed back to back, while a screw is the shape of an inclined plane spiraled around a cylinder.
Levers are rigid bars that rotate about a pivot called a fulcrum.
Levers are divided into three classes, depending on the relative positions of the handle, fulcrum, and load. The ideal mechanical advantage of a lever is equal to the distance between the handle and the fulcrum divided by the distance between the load and the fulcrum. If the sweeping motion is obtained by holding the hand on top still while moving the other hand, it is a third-class lever. All third-class levers are speed multipliers. If the hand in the middle is now held still and the hand on top moved to sweep, then it is a first-class lever.