What safety feature must engage before the escalator operates?

The safety switch is a critical safety feature that must engage before an escalator can operate. This switch typically ensures that all necessary protective measures are in place and operational, preventing the escalator from running if there are safety concerns, such as a door being open or a component being improperly installed. The engagement of the safety switch acts as a safeguard to protect both passengers and maintenance personnel, ensuring that the escalator is safe to use at the start of each operating cycle. This system is part of the broader safety protocols designed to prevent accidents and injuries related to escalator operation.

The other components mentioned do play roles in escalator safety and operation, but their function differs significantly from that of the safety switch. The emergency stop, for example, is used to halt the escalator in case of an emergency but does not prevent the escalator from starting. The comb plate serves to reduce the risk of objects getting caught at the entrance and exit of the escalator but does not impact the initial engagement process. The service brake is designed to stop the escalator during malfunction or emergency situations, but like the emergency stop, it does not engage to allow the escalator to operate initially.