Definition
In a pair of meshed gears, the driven gear is the gear that receives motion from the driving gear. It does not generate the rotational force itself; it is turned by the gear connected to the power source.
Plain English
The gear that gets pushed around by another gear. It only spins because something else is making it spin.
Context Anchor
Seen in aircraft engine and accessory descriptions, especially when explaining how one rotating part turns another.
Derivation
From the Old English 'drifan' meaning to push or force along. The driven gear is literally the one being pushed by the other gear — it receives the force rather than supplying it.
Why Pilots Care
Correct operation ensures reliable power delivery to accessories and propellers without slippage or gear damage.
Intuition Check
Driven does not mean motivated or controlled by a person here. Gear does not mean landing gear here; it means a toothed wheel in a machine.
Example Sentence 1
The magneto's driven gear meshes with the driving gear on the engine's accessory case, allowing the magneto to spin in time with the crankshaft.
Example Sentence 2
In the reduction unit the crankshaft pinion drives a larger driven gear that slows the propeller.