Abstract:
With the recent trend of high-rise buildings, it is
almost impossible for man to directly walk up and
down many stairs, because one is physically strained
not to speak of much time it takes. More difficult
is to bring up one's heavy freights to higher floors.
An elevator was devised to cope with the situation.
However, in the case of single floor and not higher
floors, that is to say, an escalator is designed for use
in frequent transportation of men and freights between
2 or 3 floors or in narrow stairs at one time.
