End-of-travel sensing detects fully opened or closed positions. Which two technologies are commonly used?

• A. Mechanical limit switches and magnetic reed switches
• B. Photoelectric sensors and inductive sensors
• C. Proximity sensors and capacitive sensors
• D. Hall effect sensors and temperature sensors

Answer: (A)

End-of-travel sensing needs a clear, reliable signal exactly when the moving part reaches the end position. Mechanical limit switches provide a direct physical contact that closes or opens a circuit as the part hits the stop, offering ruggedness, simple wiring, and a definite point of actuation—great for gates and doors where the end position is a hard physical limit. Magnetic reed switches offer a different approach: a magnet on the moving part activates the switch without any contact, so there’s virtually no wear and the system can operate in dirty or dusty environments while still delivering a crisp end-position signal. These two options cover common, durable ways to detect full travel, one being contact-based and the other contactless. Other technologies exist, but they’re less universally suited for simple, reliable end-stop signaling: optical beams can be affected by dirt or misalignment; inductive or proximity sensors require a metal target and can be overkill or less robust for simple end stops; capacitive, Hall effect, or temperature sensors don’t align as directly with the need for a straightforward end-position indication.