What does a "hotbox" detector do?

Answer: C — Senses excessive heat in wheel bearings

A "hotbox" detector is a vital safety device used on railroads to monitor the temperature of wheel bearings on freight cars. When wheel bearings become excessively hot, it can indicate that they are overheating, potentially leading to a failure or derailment of the train. The detector works by sensing the temperature of the axle bearings as the train passes by. If the temperature exceeds a predetermined threshold, the detector sends an alert to train operators, enabling them to take necessary action to avoid accidents. In contrast, measuring the speed of the train, alerting operators to track blockages, and detecting the weight of freight refer to different systems and sensors used in rail operations, each serving their unique purpose in maintaining safety and operational efficiency. Understanding the specific role of a hotbox detector emphasizes its importance in preventing mechanical failures and ensuring the safety of railway operations.