4.0 Mechanical Transportation System 4.1 Literature Review Vertical transportation is transportation of passengers traveling between floors in a building. There’re four types of lift, which are siting lift, traction lift, hydraulic lift and stair lift. Mechanical transportation systems are of vital importance in high-rise buildings. Escalators are used on lower floors for moving high volumes of people over short distances. A few retail or educational buildings have escalators for up to 10 stories. The principal means of vertical transport in tall buildings is the roped elevator. It moves by a direct current electric motor, which raises and lowers the cab in a shaft with wire ropes running over a series of sheaves at the motor and the cab itself; the ropes terminate in a sliding counterweight that moves up and down the same shaft as the cab, reducing the energy required to move the elevator. Each elevator cab is also engaged by a set of vertical guide tracks and has a flexible electric cable connected to it to power lighting and doors and to transmit control signals. Passenger elevators range in capacity from 910 to 2,275 kilograms (2,000 to 5,000 pounds) and run at speeds from 90 to 510 meters per minute; freight elevators hold up to 4,500 kilograms (10,000 pounds). The speed of elevators is apparently limited to the current value of 510 meters per minute by the acceleration passengers can accept and the rate of change of air pressure with height, which at this speed begins to cause eardrum discomfort. Elevator movements are often controlled by a computer that responds to signals from call buttons on each floor and from floor-request buttons in each cab. The number of elevators in a building is determined by the peak number of people to be moved in a five-minute period, usually in the early morning; for example, in an office building this is often set at 13 percent of occupancy. The average waiting time for an elevator between pressing the call button and arrival must be less than 30 seconds in an office building and less than 60 seconds in an apartment building. The elevators are usually arranged in groups or banks ranging from one to 10 elevators serving a zone of floors, with no more than five elevators in a row to permit quick access by passengers. In a few very tall buildings the sky lobby system is used to save elevator-shaft space. The building is divided vertically into sub-buildings, each with its own sky lobby floor. From the ground floor large express elevators carry passengers to the sky lobby floors, where they transfer to local elevator banks that take them to the individual floors within the sub-buildings. There’s also another mechanical transportation which is escalator, also named as 'moving staircase'. Escalator has the capacity to move large numbers of people with no waiting interval. Escalator is also an important architectural design impact because it can used to guide people towards main exits or special exhibits. Escalators can be constructed in three ways, two of which are parallel arrangements and one crisscross arrangement. Parallel arrangement is up and down escalators are arranged side by side or separated by distance.
1