A crane is a
lifting device that is used for lifting and moving heavy loads and
materials from the ground vertically and horizontally. The crane
is vital and integral machine needed for the construction process.
The cranes can be found at every construction site. They are
standard construction equipment that is necessary for the
construction of different kinds of structures like buildings, bridges
highways and many other structures. But mostly the cranes are used
when a tall skyscraper needs to be constructed. They are needed
because they are the only machines that are capable of lifting heavy
materials which are needed for the construction of the upper floors
of the skyscraper.
The skyscrapers are very
complex structures and require special equipment and knowledge. The
cranes which are used in the construction of the skyscrapers
are known as tower cranes. The base of the crane is actually a
concrete slab which is attached to the ground or to the sides of the
building. The concrete base is connected to the tower, and at the top
there is a control cabin which controls the crane movement. At the
big cities it is very common to see cranes on the top of the
skyscrapers performing different kinds of construction jobs. One very
interesting and intriguing question is how on Earth do they get up
there, what mechanisms or methods are used so that cranes can
reach the sky?
The most simple
explanation will be by using their own hoisting power. The crane
uses its own hoisting power to make itself taller. It raises itself
section by section, reaching top heights. But actually there are
three methods for the tower cranes to get to the top of the
skyscraper:
- External climbing method
- Internal climbing method
- Using a heavy lift helicopter or “Skycrane”
External Climbing
Method. By implementing this
method, the tower crane expands upwards. The base of
the tower crane is fixed by using concrete slabs on the ground. The
tower of the crane is lifted by using other smaller mobile crane
types. Once the building reaches more than 60 meters in height,
the tower crane is secured or tied to the building with
several steel collars, and other parts are inserted into the backbone
of the crane. In order to add segments and other parts by
itself, the tower crane is equipped with additional climbing
section- a metal sheath.
The main function of this metal sheath is to serve as a scale. The
metal sheath raises the arm of the crane
and supports the arm temporarily while it takes new segment from the
arm that needs to be placed. The metal sheath then holds the new
segment while the workers on the crane
work to put the new segment in place. The same procedure is repeated
on every 60 meters or more. The external climbing method is the most
commonly used method at the construction sites because it reduces the
time required for raising the crane.
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