The operating principle of power tools is to convert electrical energy into mechanical energy via an electric motor, which drives the tool to perform specific tasks such as rotation, impact, or reciprocating motion.

　　The operating principle of power tools is to convert electrical energy into mechanical energy via an electric motor, which drives the tool to perform specific tasks such as rotation, impact, or reciprocating motion. Different types of power tools rely on various motor principles and transmission mechanisms to deliver a wide range of functions.

　　Core principle of electric motors: Power tools typically employ either DC or AC motors, both of which are based on the law of electromagnetic induction. When an electric current passes through a conductor placed in a magnetic field—such as the rotor windings of a motor—the conductor experiences a force (the Ampère force), resulting in rotational motion. DC motors achieve continuous unidirectional rotation via a commutator and brushes, while AC motors—such as induction motors—rely on the rotating magnetic field generated by the stator to drive the rotor.

　　Common transmission and motion types: The rotational motion of the motor is converted into the specific motion required by the tool via transmission mechanisms such as gears and linkages.
Rotational motion: For example, in electric drills and electric screwdrivers, the motor drives the drill bit or screwdriver bit to rotate at high speed, either directly or via a reduction mechanism.

　　Reciprocating impact motion: As in an electric hammer, the motor drives a crankshaft–connecting rod–piston assembly that reciprocates within the cylinder to compress air, creating periodic pressure fluctuations. These fluctuations propel the hammer to deliver high‑frequency impacts on the drill bit’s tip, while the drill bit simultaneously rotates.

　　Reciprocating shearing motion: For example, electric scissors and electric sheep shears—here, the motor drives the cutting blade to perform high-speed reciprocating motion via a transmission mechanism (such as an eccentric mechanism), thereby achieving shearing. In an electric sheep shear, the upper blade swings back and forth relative to the fixed lower blade to cut the wool.

　　Vibrational motion: For example, electric toothbrushes use a reduction motor or a brushed motor, and through a transmission system comprising gears, linkages, and other components, convert the motor’s rotational motion into high-frequency rotation of the brush head or sonic vibrations.