Safety Elevator

The passenger elevator with an automatic brake that grips if the hoisting rope fails, demonstrated theatrically by Elisha Otis at the New York exhibition of 1854 when he cut the rope of the platform he stood on. Without it upper floors were the cheap floors; with it height became valuable, and the tall building became worth constructing at all. The device that actually catches a falling cab is the governor, a speed-sensing mechanism credited to Otis himself: it detects a car descending faster than its rated speed and forces braking shoes to clamp against the guide rails in the shaft, arresting the fall without a jolt severe enough to injure the passengers inside. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/