By Chris Deziel
Updated Aug 30, 2022
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Electric motors are built on the principle of electromagnetic induction, first articulated by physicist Michael Faraday in the early 1800s. Faraday discovered that moving a magnet through a coil of wire induces an electric current. Modern motors harness this effect in reverse: when electric current passes through a coil, it becomes magnetized, creating a magnetic field that interacts with another magnetic field to produce rotational motion.
The main components of an electric motor are the stator, rotor, brushes, commutator (for DC motors), gears or belts, and bearings. These parts work together to generate torque, transfer power, and reduce friction, ensuring efficient operation.
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Modern commercial motors typically rely on electromagnets rather than permanent magnets. The stator consists of multiple coils arranged in a circular pattern that generate a stationary magnetic field. The rotor, a coil wound around an armature attached to the shaft, spins within this field. Because the rotor is in motion, metallic brushes maintain electrical contact with a conducting surface on the stator, allowing current to flow into the rotor coil.
When the motor is powered, electricity energizes the stator windings to create a steady magnetic field and flows through the brushes to activate the rotor coil. In DC motors—such as those powered by batteries—a commutator mounted on the rotor shaft reverses the current direction with each half-turn, keeping the rotor turning in a single direction.
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While the motor shaft turns, it often needs to drive other equipment. Gears and drive belts transfer this rotational energy to different shafts, adjusting speed and torque as required. By varying gear ratios or belt arrangements, a motor can either increase rotational speed (and reduce torque) or boost torque (and reduce speed). Worm‑drive gears can also shift rotation by 90 degrees, offering versatile motion control.
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Friction between moving parts can diminish a motor’s efficiency and shorten its lifespan. Bearings situated between the stator and rotor maintain the rotor’s central alignment, minimizing the air gap and reducing resistance. Small motors typically use ball bearings, while larger units employ roller bearings. Regular lubrication and maintenance of bearings, along with cleaning of windings and brushes, are essential for sustained performance.
