Definition
An electrical switch that automatically opens or closes a circuit when a moving mechanical component reaches a specified position, used in landing gear systems to stop gear motor operation once the gear is fully extended or fully retracted and to signal gear position to the cockpit.
Plain English
A switch that gets tripped by a moving part when it reaches the end of its travel. In landing gear, it tells the system 'the gear is all the way down' or 'all the way up' and shuts off the motor at the right moment.
Context Anchor
Seen in landing gear system descriptions, especially when explaining gear motors, gear position lights, and why the gear stops moving at the proper point.
Derivation
From 'limit' (the boundary or end point of travel) and 'switch' (an electrical control). The name describes its job: it switches the circuit at the limit of motion.
Why Pilots Care
It stops the motor or actuator at the correct travel limit to prevent damage and triggers cockpit position lights or warnings.
Analogy
A limit switch is like the switch in a refrigerator door light: the switch changes when the door reaches a certain position. In the landing gear system, the moving gear or linkage does the pressing or releasing instead of your hand.
Intuition Check
A limit switch is not a switch the pilot normally flips, and it does not limit aircraft performance. It is a position-sensing switch that reacts when a part reaches the end of its movement.
Example Sentence 1
When the landing gear reached the fully extended position, the limit switch cut power to the gear motor and turned on the green down-and-locked light.
Example Sentence 2
During retraction the limit switch cut power to the hydraulic pump once the main gear locked in the up position.