What maintenance task is critical to prevent escalator breakdowns?

Monitoring step chain tension is a critical maintenance task for escalators because the step chain is integral to the escalator's operation. Proper tension ensures that the step chain runs smoothly, aligning correctly with the escalator steps and maintaining the safety and reliability of the system. If the step chain is too loose, it can lead to unwanted movement or misalignment, which can cause significant operational issues. Conversely, if it is too tight, it may increase wear and tear on components, potentially leading to a breakdown. Regular monitoring allows for timely adjustments, ultimately ensuring the escalator remains in safe working order.

The other choices, while related to maintenance, do not address the fundamental operational aspects in the same way. For instance, regularly replacing the handrail is important for user safety but does not directly influence the machine’s operational integrity. Cleaning comb plates is necessary for safety and cleanliness but is less critical than ensuring the mechanical parts are functioning properly. Repainting the steps does not affect the performance or safety of the escalator; it is primarily a cosmetic task. Hence, monitoring step chain tension stands out as the most crucial maintenance task for preventing breakdowns.