Definition
A positive-displacement pump that uses two meshing gears rotating inside a close-fitting housing to move fluid. Fluid is drawn into the spaces between the gear teeth on the inlet side, carried around the outside of the gears against the housing wall, and forced out the discharge side as the teeth re-mesh. Each rotation moves a fixed volume of fluid, so output is steady and predictable for a given pump speed.
Plain English
A pump with two interlocking gears inside a sealed case. As the gears turn, they trap fluid between their teeth and the case wall and push it from the inlet to the outlet. Every turn moves the same amount of fluid.
Context Anchor
Seen in aircraft hydraulic, fuel, and oil system descriptions, especially when explaining how fluid flow or pressure is produced.
Derivation
“Gear” commonly means a toothed wheel used to transfer motion. “Pump” means a device that moves fluid. Together, “gear-type pump” describes a pump whose main moving parts are gears.
Why Pilots Care
Gear-type pumps are workhorses in aircraft hydraulic and lubrication systems. Knowing they are positive-displacement helps explain why these systems need pressure relief valves -- the pump will keep pushing fluid regardless of downstream pressure, which can cause damage if there is no relief path.
Analogy
Picture two close-fitting toothed wheels turning together. Fluid gets carried around the outside edges between the teeth and the case, then is squeezed out at the other side.
Intuition Check
“Gear-type” does not mean a pump used only for landing gear. Here, “gear” means the toothed wheels inside the pump that move the fluid.
Example Sentence 1
The engine-driven gear-type pump supplies pressurized oil to the lubrication system whenever the engine is running.
Example Sentence 2
During inspection the mechanic checked the gear-type pump for scoring on the gear teeth.