Definition
An electrical switch that opens or closes its contacts automatically when the rotating shaft it is mounted on reaches a specified speed. As the shaft spins faster, weights inside the switch are thrown outward by centrifugal force, moving a mechanism that operates the contacts.
Plain English
A switch that turns itself on or off based on how fast something is spinning. When the shaft spins fast enough, the switch flips; when it slows down, it flips back.
Context Anchor
Seen in aircraft electrical systems, especially in starters, motors, and equipment where an electrical circuit must change after a rotating part reaches operating speed.
Derivation
From Latin centrum (center) and fugere (to flee). Centrifugal literally means 'fleeing the center' — describing the way spinning weights are flung outward. That outward motion is what physically operates the switch.
Why Pilots Care
Centrifugal switches are common in starter and ignition circuits. When the engine reaches a certain speed, the switch automatically disconnects the starter or shifts the ignition system out of its starting mode. If the switch fails, the starter may stay engaged or the ignition may not transition properly.
Intuition Check
Do not think of this as a switch the pilot normally flips by hand. The key idea is automatic operation caused by rotation speed.
Example Sentence 1
Once the engine spooled up, the centrifugal switch dropped the starter out of the circuit automatically.
Example Sentence 2
During preflight the mechanic verified the centrifugal switch closed below 800 RPM to allow starter engagement.