Plain English Meaning

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.

Full 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.

Context Anchor

Seen in discussions of retractable landing gear operation, especially during normal extension, retraction, and landing gear system troubleshooting.