Definition
A continuous metal ring mounted on a rotating shaft that allows electrical current to be transferred between the rotating part of a machine and a stationary external circuit through stationary brushes that ride against the ring's surface.
Plain English
A smooth metal ring that spins with a shaft so that stationary carbon contacts can rub against it and pass electricity in or out of the moving part without the wires twisting up.
Context Anchor
Seen in aircraft alternator and generator maintenance, especially when checking brushes, charging output, or worn rotating electrical parts.
Derivation
Called a slip ring because the stationary brush slips (slides) continuously against the rotating ring while staying in electrical contact. The name describes exactly what happens at the contact point.
Why Pilots Care
Slip rings are a common wear point in aircraft alternators and tachometer generators. When they become dirty, pitted, or worn, electrical output becomes erratic — a frequent cause of charging system and instrument problems on the ramp.
Analogy
Think of a record player needle resting on a spinning record. The record turns freely while the needle stays put and keeps contact the whole time. A slip ring works the same way, but it carries electricity instead of sound.
Intuition Check
Do not read “slip” as a loose or uncontrolled movement here. In a slip ring, the sliding contact is the normal design that lets electricity reach a rotating part.
Example Sentence 1
During the alternator inspection, the technician cleaned the slip rings and checked the brushes for proper spring tension.
Example Sentence 2
Technicians inspect the slip rings and brushes during propeller de-icing system maintenance.