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These stairs are known as escalators or ever-moving flights of electrically –operated stairs. These escalators are kept in motion by a revolving drum. A few steps at top and bottom are kept level though moving individually. The only thing a person has to do is to occupy a step of the escalator for his upward or downward motion. The important features of the escalators are described below:
Parts of an Escalator
An escalator consists of three parts: steel trussed framework, handrails and an endless belt with steps. Accurately prepared tracks are attached to the steel trusses and the steps move on these tracks.
Speed and slope
The usual accepted speed of the moving stair is 45 cm per second. A moving stair is in the form of an inclined bridge between two successive floors and its pitch or inclination to the horizontal is kept 30 0
Design
Various components of a moving stair should be carefully designed for the loads likely to come over them. The important factor affecting the design is the floor-to-floor height. The stairway should be kept independent by providing a structural frame around the stair well. This structural frame takes the load of floor, handrail , etc.
Location
Before the position of a moving stair in a building is decided, a careful study of flow of traffic should be made or if it is a new structure, the moving stairs should be located at points where the traffic is likely to be heaviest.
Installation
Various parts of a moving stair are prepared in the work-shop and they are then brought on site for installation. The process of installation should be carefully done so as to fit each part of the stair in its proper position. This arrangement will ensure smooth working of the stair. Moreover, the escalators are arranged in pairs – one for upward movement and the other for downward movement. The units may be placed parallel to each other or diagonally opposite to each other.
Advantages
The moving stairs consume less power, possess large capacity and require no operators for their working. It is estimated that a moving stair of width 120 cm can carry traffic of 8000 persons per hour.
Uses
The escalators are generally used when traffic of persons is heavy between the floors. They are used for commercial buildings, tube railways, etc.
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