Definition
Hydraulic cylinders that physically extend and retract the landing gear. Pressurized hydraulic fluid is directed into one side of each cylinder, pushing a piston that drives the gear leg up into its wheel well or down into the locked, ready-to-land position.
Plain English
These are the parts that actually move the wheels up and down. They use hydraulic pressure to push the gear into place when the pilot selects gear up or gear down.
Context Anchor
Seen in discussions of retractable landing gear operation, especially during normal extension, retraction, and landing gear system troubleshooting.
Derivation
Actuating comes from the Latin actus, meaning to drive or set in motion. An actuating cylinder is a cylinder whose job is to make something move — in this case, the landing gear.
Why Pilots Care
Reliable operation ensures the landing gear extends and retracts correctly for safe takeoffs and landings.
Intuition Check
Cylinder here does not mean an engine cylinder. It means a tube-and-piston part that pushes or pulls the landing gear. Gear here means landing gear, not a gear in a transmission.
Example Sentence 1
When the pilot selected gear down, hydraulic fluid flowed to the gear actuating cylinders and the wheels swung into the locked-down position.
Example Sentence 2
During preflight the mechanic inspected the gear actuating cylinders for leaks and proper fluid pressure.