Defect detector

Okay kiddo, a defect detector is like a special machine that checks trains to make sure everything is working properly.

When a train passes by, the detector uses sensors to check the wheels and brakes to make sure they're doing their job. It also checks for things like damaged parts or leaks that could cause problems later on.

If the detector finds something wrong, it sends a message to the people who work on trains to let them know there's a problem. That way, they can fix it before the train goes on any further.

Think of it like a doctor checking you out to make sure you're healthy. The defect detector checks the train to make sure it's safe and won't cause any problems for the people on board.