Classroom on demand

Welcome to Classroom on demand, your source for educational materials related to the vertical transportation industry. This site represents the knowledge and expertise of the best engineers and mechanics in the elevator industry, and will help those new to the elevator industry learn about the basic workings of elevator systems, and also will serve as a reference for people with more experience.


A device that provides a physical lock for hoistway door and gives an electrical signal which allows the car to run.

Tags:  Entrance Safety Doors

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