Definition
A fragment of a longer dictionary entry describing how an AC induction motor works: stationary pole pieces (shoes) in the motor's stator are energized in sequence by alternating current, producing a magnetic field that appears to rotate around the inside of the motor. A squirrel-cage rotor — a cylindrical rotor made of conductor bars shorted together at each end, resembling the wire wheel a pet squirrel runs in — is dragged along by this rotating field, which is what makes the motor turn.
Plain English
Inside an AC motor, the fixed magnetic poles are switched on and off in turn so the magnetic pull seems to spin around in a circle. The rotor in the middle, shaped like a squirrel's exercise wheel made of metal bars, gets pulled along behind that spinning pull and turns the shaft.
Context Anchor
Seen in aircraft electrical-system and maintenance discussions of small AC induction motors, especially shaded-pole motors.
Derivation
Pole shoes are called 'shoes' because they are the shaped iron pieces that 'fit' onto the ends of the field windings, much like a shoe fits onto a foot. 'Squirrel-cage' comes from the rotor's resemblance to the round wire cage a pet squirrel runs inside.
Why Pilots Care
AC induction motors using this design power many aircraft accessories. Knowing that the rotor follows a rotating field — rather than being driven by brushes and commutators like a DC motor — explains why these motors are simple, reliable, and have no brushes to wear out.
Analogy
Imagine standing in the middle of a circle of friends who take turns tugging on a rope tied around your waist, each pulling just as the previous one lets go. You'd end up spinning in place, chasing the pull. That's how the rotor follows the rotating magnetic field.
Intuition Check
Do not read shoes as footwear. Here, shoes are shaped metal pole pieces inside an electric motor that guide magnetic force.
Example Sentence 1
The fuel boost pump uses an AC induction motor in which the stator shoes produce a rotating magnetic field that the squirrel-cage rotor follows.
Example Sentence 2
During preflight checks the APU motor relies on shoes creating the rotating field so the squirrel-cage rotor spins smoothly.