Definition
An internal supercharger driven mechanically by the engine's crankshaft through a system of gears, used to compress the air-fuel mixture before it enters the cylinders so the engine can produce more power, particularly at higher altitudes where the air is thin.
Plain English
A pump that squeezes air into the engine to boost its power. It is connected to the engine itself by gears, so the engine spins the pump as it runs.
Context Anchor
Seen in aircraft engine and high-altitude performance discussions, especially on piston engines designed to keep power as altitude increases.
Derivation
Supercharger' comes from 'super-' (above, beyond) and 'charge' (the air-fuel mixture loaded into a cylinder). 'Gear-driven' specifies how it gets its power: a set of gears connects it directly to the engine, rather than being spun by exhaust gases like a turbocharger.
Why Pilots Care
It delivers boost immediately and consistently but uses some engine power to operate, affecting fuel consumption and available horsepower.
Analogy
It is like using a pump to push more air into a fire so it burns stronger. The engine gets more air than it would get from normal outside pressure alone.
Intuition Check
“Gear-driven” does not mean related to the landing gear. Here, “gear” means toothed wheels inside the engine system that mechanically turn the supercharger.
Example Sentence 1
The radial engine on this older airliner uses a gear-driven supercharger to maintain takeoff power up to its critical altitude.
Example Sentence 2
Maintenance on the gear-driven supercharger requires checking gear wear and oil pressure to the drive system.