Başlık: Escalator Suddenly Accelerates at Bangladesh University, Triggering Panic Among Students
From campuses and shopping malls to metro stations and airports, we use escalators without giving them much thought. As we check our phones or chat with friends, trusting the steps to move at a steady pace, we rarely stop to consider the mechanism behind them.
At BRAC University in Dhaka, the capital of Bangladesh, an escalator carrying dozens of students suddenly sped up. As a crowd gathered on the lower level, trying to figure out what was happening, the scene left viewers holding their breath. Fortunately, no one was injured.
You can watch it here;
We’re used to escalators coming to an abrupt stop, but how can they speed up?
Escalators are designed to run at a steady speed under normal conditions, so a sudden surge can have several causes. One of the most common is a failure in the main brake or gearbox. If power to the motor is cut or the stop button is pressed, worn brake pads or a brake mechanism that fails to engage can break the connection between the motor and the steps. This is especially dangerous on a descending escalator carrying a heavy load of passengers: the steps may begin moving under the passengers’ weight alone, causing them to speed up without warning.
Electrical control faults are another possible cause. Many modern escalators use motors fitted with variable-frequency drives to save energy. When no one is around, the escalator slows down; as someone approaches, it returns to its normal speed. A software or electronic fault in the motor drive board—or a faulty sensor—can send the motor the wrong frequency or voltage.
Mechanical wear can also play a part. Step chains and main drive gears are built to withstand heavy loads, but poor maintenance, inadequate lubrication, or excessive passenger loads can wear down the gears. If they strip, the step chain may come loose and slide rapidly toward the lower end under its own weight.
Escalators are also normally equipped with overspeed sensors and backup braking mechanisms. If the steps are detected moving 20 to 25 percent faster than normal, these systems should lock the escalator mechanically. When secondary safety devices and emergency brakes fail to activate in incidents like these, the cause is often linked to poor maintenance.
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