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July 10, 2011
Elevators have been around for thousands of years mostly to move large objects for construction as they were too dangerous to move people. But in 1852, Elisha Otis solved this problem when he invented safety elevator. Otis design allowed for clamps to engage the side rails of the elevator when the cables failed, thus stopping the elevator from plummeting to the ground floor. In 1854 Otis presented his design at the Crystal Pavilion in New York. In a bit of showmanship when he stood in his elevator and had the cables severed in front of a curious crowd. Needless to say the sales of his elevators took off. A company bearing his name is still manufacturing elevators to this day.

Elevator types

The two most common types of elevators are the Hydraulic elevator and the Traction elevator. Hydraulic elevators use a piston and hydraulics to move the elevator cab up and down. They are limited to 60 feet in height and are slow. Traction elevators driven with an electrical motor and use cables and a counter weight to move the elevator cab up and down. They have an unlimited height and are faster. (There are several other types of speciality elevators; residential, freight, stage, ect, but for the purposes of the ARE these are the most common ones used.)


Regardless of the type of elevator there are several components that are the same:

  1. Elevator Cab moves the passengers up and down.
  2. Elevators shafts are CMU enclosures that are fire rated and able to support the attachment of the side rails.
  3. The elevator mechanical room is either placed next to the elevator shaft (hydraulic elevators) or above the shaft (traction elevators) This is where all the controlling mechanisms are stored for the elevator.
  4. passenger controls: These are the buttons that are located in the cab and at each floor that direct the elevator to the desired floors.

 Sky Lobbies

The elevator is an essential component to the skyscraper, without it we wouldn’t have them. In a skyscraper real estate is valuable, to have each elevator serve each floor would mean a lot of elevators and a lot of wasted space. The design of the John Hancock tower in Chicago first took advantage of the concept of Sky Lobbies. Sky Lobbies bundled multiple elevators into one shaft. For example in a 40 story building you might have a sky lobby on the 21st floor. This allows one shaft to be used as an express elevator to the sky lobby and the remainder of the elevator shafts to house two elevators, one serving floors 1 through 20 and another serving floors 21 through 40 thus reducing the amount of elevator shafts needed. Without the invention of sky lobbies the modern sky scraper would look very different.


(Image credit)

Good luck on your next exam.

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