Elevators are an important feature in commercial buildings
Elevators are an important feature in commercial buildings, office complexes, hospitals and shopping centers. They provide quick transportation for people while saving time and energy that would otherwise be needed to climb stairs. They are designed to provide a comfortable, reliable ride with minimal noise and vibration. In addition to their functionality, passenger elevators add a design element that can enhance the overall appearance of a building.
A passenger elevator is an electrically powered lift car that can carry passengers and light loads, typically ranging from 907 kg (2,020 lb) to 2268 kg (5000 lb). They usually have a smaller capacity than freight elevators. In modern architecture, the rise of skyscrapers has increased the demand for passenger elevators, which can move cars and a total load of up to 20 times per hour or 0.6 meters per second.
Modern passenger elevators are designed to be as quiet as possible, with special sound insulation and smooth riding hydraulics that minimize the effects of speed changes and other environmental factors. They also have a number of features to prevent injuries and snags in the doors, including safety sensors that monitor door movement and a reversing mechanism for doors that may encounter obstructions.
Most passenger elevators are grouped into control areas
, which serve multiple floors within the same building, to maximize efficiency and reduce maintenance. The control system is typically located in the hoistway and controls the traction motors, which drive the elevator car. The cab is attached to the hoistway by two or more wires, which are looped over the drive sheave and over a counterweight that is hung from the ceiling. As the car goes up, the counterweight goes down and vice versa, reducing the power required to operate.
The door opening and closing are controlled by the car's electric motor, and safety sensors ensure that persons or objects cannot be caught in the doors as they close. In the event that an object blocks an elevator, a photoelectric sensor detects the object and reverses the direction of the doors. The door reversal is usually accompanied by an audio-visual alarm to warn passengers that the elevator is about to close.
Some elevators are specialized to carry medical patients or may be equipped with front and rear entrances for disabled access. They may have special signage or even a double-decker car. In a public building, the elevator can have an LCD screen that displays its floor numbers and shows messages to passengers. Specialized "smart elevator" systems can display additional information about the building, such as energy consumption and recycling initiatives.
While elevator technology has advanced significantly beyond its early physics-based challenges
, it continues to face many human-centered issues. For example, passengers often complain about the ear-popping effect caused by a rapid change in cabin air pressure as an elevator ascends and descends. This is much more noticeable in very high-rise buildings, where the elevators must decline and ascend more rapidly than airplanes. Similarly, passengers often dislike the odors that can be emitted by the propulsion system or the cab interior.