used electric motor is an electrical machine that converts electrical energy into mechanical energy. Most Heavy Electric Motors operate through the interaction between the motor‘s magnetic field and electric current in a wire winding to generate force in the form of rotation of a shaft. Electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. Generators mechanically identical to an electric motor, but operate in the reverse direction, converting mechanical energy into electrical energy.

Electric motors may be classified by considerations such as power source type, internal construction, application and type of motion output. In addition to AC versus DC types, motors may be brushed or brushless may be of various phase (single-phase, two-phase, & three-phase), and maybe either air-cooled or liquid-cooled. General-purpose motors with standard dimensions and characteristics provide convenient mechanical power for industrial use. The largest electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors are found in industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives.

In certain applications, such as in regenerative braking with traction motors, heavy electric motors, second-hand electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction.

Electric motors produce linear intended to propel some external mechanism, such as a fan or an elevator. An electric motor is generally designed for continuous rotation or for linear movement over a significant distance compared to its size. Magnetic solenoids produce significant mechanical force, but over an operating distance comparable to their size.