A machine (or mechanical device) is a mechanical structure that uses power to apply forces and control movement to perform an intended action. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors that monitor performance and plan movement, often called mechanical systems.
Renaissance natural philosophers identified six simple machines which were the elementary devices that put a load into motion and calculated the ratio of output force to input force, known today as mechanical advantage.
Modern machines are complex systems that consist of structural elements, mechanisms, and control components and include interfaces for convenient use. Examples include a wide range of vehicles, such as automobiles, boats, and airplanes; appliances in the home and office, including computers, building air handling and water handling systems; as well as farm machinery, machine tools, and factory automation systems and robots.
Machines generating mechanical energy
The machines generating mechanical energy are also called prime movers. These machines convert some form of energy like heat, hydraulic, electrical, etc into mechanical energy or work. The most popular example of these machines is the internal combustion engine in which the chemical energy of the fuel is converted into heat energy which in turn is converted into mechanical work in the form of the rotation of the wheels of the vehicle. Some other examples of this group of machines are gas turbines, water turbines, steam engines, etc.
Machines transforming mechanical energy
These machines are called converting machines because they convert mechanical energy into other forms of energy like electricity, hydraulic energy, etc. Some examples of these machines are an electric generator in which the rotation of the shaft is converted into electrical energy and a hydraulic pump in which the rotation energy of the rotors is converted into the hydraulic energy of the fluid.
Machines utilizing mechanical energy
These machines receive mechanical energy and utilize it for various applications. Some examples of these machines are lathe machine that utilizes the mechanical energy to cut metals and washing machine that utilizes the rotation of the rotor for washing the clothes.