A machine is a set of mechanisms consisting of various machine elements such as gears, bearings and shafts to transform any type of energy into another energy, to do a job by using a certain power or to create an effect. Electronic or organic devices that do not have any mechanical parts are also called machines. Machines have been developed to assist or completely replace human or animal power in the performance of a specific task or a physical function. They cover a wide range of devices, from simple machines such as levers, inclined planes, spinning wheels to very complex systems such as a modern automobile. Machines can operate by converting thermal, chemical, nuclear or electrical energy into mechanical energy and vice versa, or simply function to transmit or adapt forces and motion. All machines are equipped with an input and output equipment and adaptation or conversion and transfer equipment. Machines that take input energies (input) from natural resources such as wind, streams, coal, petroleum or uranium and convert this energy into mechanical energy are called primary activators (primary motors). Windmills, water wheels, turbines, steam engines and internal combustion engines are primary actuators. The output energy (output) obtained from these machines can be fed as input to other machines such as electric generators, hydraulic pumps or compressors, mostly through rotary shafts. These last three devices are classified as generators (generators); The electrical, hydraulic and pneumatic energy outputs of these devices can be used as inputs in electrical, hydraulic or air motors. These motors are used to operate materials processing machines such as machine tools, packaging and transport machines, or machines that produce various types of output, such as sewing machines and washing machines.
The machines that do not fall into the primary actuator, generator or motor class are called the processor (operator machine); The category of processors includes all manually operated devices such as calculators and typewriters. In some cases, machines of all categories are collected in a single unit. For example, in a diesel-electric locomotive, the primary actuator is the diesel engine; this motor powers the electricity generator, and the generator drives the motors that turn the wheels.