Definition
A clutch that engages automatically when the input shaft reaches a certain rotational speed. Weighted shoes inside the clutch are thrown outward by centrifugal force as speed increases, pressing against an outer drum and transferring power to the output shaft. At low speeds, springs hold the shoes inward and no power is transmitted.
Plain English
A speed-sensitive coupling that connects a spinning engine to whatever it drives only after the engine is turning fast enough. Below that speed, the engine spins freely and the load is disconnected.
Context Anchor
Seen in aircraft engine and rotor drive discussions, especially where power is connected automatically as engine speed rises.
Derivation
From Latin centrum (center) and fugere (to flee). Centrifugal literally means 'fleeing the center' — describing how the weighted shoes are thrown outward as the shaft spins faster. The clutch's behavior is built directly into its name.
Why Pilots Care
It provides smooth automatic engagement, reduces risk of engine stall at low RPM, and simplifies operation in rotorcraft and some light aircraft.
Analogy
It works like an automatic connector: when the engine is turning slowly, it stays loose; when the engine turns fast enough, it grips and starts passing power along.
Intuition Check
Do not read “centrifugal” as just meaning “spinning.” The important idea is that parts inside the clutch move outward as they spin faster, and that outward movement makes the clutch grip.
Example Sentence 1
The starter uses a centrifugal clutch that engages the engine only after the starter motor reaches sufficient speed.
Example Sentence 2
During preflight, the mechanic checked that the centrifugal clutch released cleanly at idle.