Definition
A mechanical fitting used to connect a rotating component, such as an engine accessory, to its drive shaft so that rotational motion is transmitted from the engine to the accessory. Drive couplings are commonly designed to shear or disengage if the accessory seizes, protecting the engine from damage.
Plain English
A small fitting that links a spinning engine part to whatever it drives, so the two turn together. Many are built to break on purpose if the driven part jams, so the engine itself isn't harmed.
Context Anchor
Seen in aircraft maintenance discussions involving engine-driven accessories such as alternators, pumps, and ignition components.
Derivation
From 'drive' (to cause to move) and 'couple' (from Latin copula, meaning a link or bond). A drive coupling is literally the link that lets one part drive another.
Why Pilots Care
A failed drive coupling can stop magneto operation, leading to loss of ignition and possible engine power loss.
Intuition Check
Do not think of a drive coupling as just any connection or mounting bracket. It specifically connects rotating parts so one can turn the other.
Example Sentence 1
When the vacuum pump failed in flight, the mechanic later found the drive coupling had sheared, just as it was designed to do.
Example Sentence 2
A sheared drive coupling prevented magneto damage when the accessory seized during flight.