What is the function of a limit switch in a mechanism?

• A. To measure speed.
• B. To detect end-of-travel and provide a definite input to stop or change motion.
• C. To reset the microcontroller.
• D. To increase torque.

Answer: (B)

A limit switch is a position-sensing device that activates when a moving part reaches a predefined location. It provides a definite input to the control system, telling it to stop, slow down, or reverse motion to prevent over-travel or collisions. This makes it a reliable way to detect end-of-travel and enforce safe, repeatable boundaries for a mechanism. It isn’t used to measure speed, reset a microcontroller, or increase torque—the switch simply signals position to control how the motion should proceed.