What signals the system is fully raised or retracted and causes the electric motor to be de-energized?

What signals the system is fully raised or retracted and causes the electric motor to be de-energized?

• A. End position lights
• B. Pressure sensor readings
• C. Limit switches
• D. Runway proximity sensors

Answer: (C)

Limit switches provide a definitive signal that a mechanism has reached its end stops and should stop moving. When the moving part reaches the fully raised or retracted position, the switch’s actuator is pressed, changing the electrical state and interrupting power to the motor or triggering a stop relay. That de-energizes the motor and holds the system in place, preventing over-travel, damage, or safety hazards. End position lights only indicate that the end has been reached; they don’t inherently stop the motor. Pressure sensor readings measure force or pressure rather than position, so they aren’t reliable end-of-travel signals for a mechanical lift. Runway proximity sensors are designed to detect distance to a surface in a different context and aren’t the standard means to end travel for a simple raise/lower mechanism.

Limit switches provide a definitive signal that a mechanism has reached its end stops and should stop moving. When the moving part reaches the fully raised or retracted position, the switch’s actuator is pressed, changing the electrical state and interrupting power to the motor or triggering a stop relay. That de-energizes the motor and holds the system in place, preventing over-travel, damage, or safety hazards.

End position lights only indicate that the end has been reached; they don’t inherently stop the motor. Pressure sensor readings measure force or pressure rather than position, so they aren’t reliable end-of-travel signals for a mechanical lift. Runway proximity sensors are designed to detect distance to a surface in a different context and aren’t the standard means to end travel for a simple raise/lower mechanism.