Lever At other instances, it is straightforward to identify basic machines: a door, for example, contains hinges (which function as levers) and a door knob (a wheel-and-axle).
In reality, there are many more complicated devices that use levers as an integral part of their function. For example, a car has multiple levers: the steering wheel, the gearshift, the brake pedal, and so on.
A lever can be used as a simple mechanism to amplify force. In this role, it is called "mechanical advantage". For example, if you lift a 100-pound load with a 10-foot pole, then one could argue that you have used a mechanical advantage of 10:1.
In modern technology, levers are used in instruments panels, fork lifts, and drafting tables. Levers also form a fundamental part of many machines: for example, steam engines, gas engines, and electric motors all use levers to vary the power transmitted to the driving wheels.
The word "lever" comes from old French laver meaning to wash or clean. Thus, a lever is any object that helps to wash or clean.
In conclusion, a hinged door is a simple device but it is not the only one.
A hinge is an example of a lever, which is a form of basic machine. To move an object, a lever employs a stiff beam coupled to a pivot point. As the name implies, hinges are used to connect two objects together, allowing them to swing open or closed. Hinges are found in many devices that require flexible connection pieces: doors and windows can be moved using hinges as their name suggests.
Hinges come in many shapes and sizes. They can be hand-made from wood or metal, but most often they are manufactured from steel and aluminum alloys. Hinges are rated by the number of teeth they contain; the more teeth, the easier it is to open the door or window. Unusually shaped hinges can be difficult to open, while extremely flat ones may be hard to close completely.
The first hinges were made from cast iron and were used on wooden doors before metal framing was invented. The first metal hinges were made from silver and were used on church doors until about 1810. Today, most household doors are still made from wood, but they usually have plastic or metal inserts in the frame to hold the door in place when it is opened or closed. These inserts are called "door stops."
Household appliances also use hinges.
A lever is a basic mechanism consisting of a stiff beam and a pivot. Both the effort (input force) and the load (output force) are applied to the beam's ends. When one end of the lever is pushed, the other end of the lever receives a load. A simple machine using a single-acting piston and cylinder is shown in figure: The input force is applied to the piston, which moves up or down inside the cylinder. This forces the rod attached to the piston down or pulls it up, which in turn applies or releases the load on the lever.