New Delhi, Delhi, India – Nine people injured after apartment building falls one floor

Nine people suffered minor injuries around 2:50 p.m. local time, June 18, 2013, when an elevator in an apartment building in New Delhi, Delhi, India apparently “slipped” one floor, falling from the fourth floor before stopping suddenly at the third floor. The victims were all taken to a nearby hospital, where they received first aid and were released. No information was available regarding the cause of the malfunction.

Based on the the description of the incident, it appears that the elevator may have descended uncontrollably, causing the elevator to overspeed downwards, causing the overspeed governor to apply the car safety. Typically, when an elevator exceeds its rated speed, the overspeed governor will first trip electrically, sending a signal to the elevator controller to stop the car. If the controller is unable to stop the car and the car continues to accelerate downward, it will then trip mechanically. When the governor trips mechanically, jaws on the centrifugal governor grab the governor cable. The energy of the descending car then causes the governor cable, which is now fixed, to engage the car’s emergency brakes, which clamp down on the guide rails, stopping the car.

In the United States, the ASME A17.1 “Safety Code for Elevators and Escalators” provides that when the overspeed governor trips mechanically, the car should not decelerate at a rate greater than “1 G”, the rate of normal gravitational acceleration, or 9.8 meters per second-squared. It should be noted that a downward acceleration of “1 G” would cause an elevator rider to experience a relative weight twice their normal weight. That is, a passenger would “weigh” twice their normal weight relative to the elevator floor below their feet, so it is not difficult to understand how a passenger would be thrown around and injured when an elevator stops during a high speed mechanical safety application. However, had the mechanical safety not been provided or malfunctioned, the elevator would have continued to decelerate until it reached terminal velocity and crashed into the pit at the bottom landing, so despite that these passengers suffered minor injuries, they should consider themselves lucky that the safety devices worked as designed, allowing them to escape potentially fatal injuries.

Sources reporting this story locally include:

Leave a Comment

Your email address will not be published. Required fields are marked *