What stops lift at maximum speed of 75 fpm?

• A. Overspeed Safety Sensor
• B. Aircraft Cable Design
• C. Safety Governor
• D. Horsepower Requirement

Answer: (C)

The device that controls and limits how fast an escalator can run is the safety governor. As the drive turns, the governor senses the belt or chain speed and, once the set limit is reached (75 fpm in this case), it automatically cuts power to the drive or otherwise trips the drive mechanism to stop the escalator in a controlled way. This is the primary mechanism that enforces the maximum speed and brings the lift to a halt if the limit is reached.

An overspeed safety sensor serves as a backup protection: it detects speeds that exceed the safe limit and triggers a stop if something pushes the system beyond the intended maximum. But the governor is the component that establishes and enforces that maximum speed, rather than simply reacting to an overspeed condition.

The other options—aircraft cable design and horsepower requirement—relate to components’ strength and the motor’s power capacity, not to automatically stopping at the maximum speed.