CRANES
Cranes are a wonder of complex geometry, and use a combination of
winches to lift hoist materials up the tower.
The silent gentle giants standing above MahaNakhon are Linden
Comansa cranes, provided to Bouygues Thai by Smart Co., Ltd., the
leading local supplier of tower cranes with 30 years of experience
in the industry.
As each load is lifted, the crane operator drives three different
winches, one for each type of movement:
• The hoisting movement, that moves the load up and down
• The distribution movement, that moves the load back and forth
along the jib
• The slewing movement, that allows the crane (with the load) to
move right or left around the mast of the crane
It seems to be simple, but it is a complex system, which enables a
slender crane to lift very heavy loads efficiently and effectively.
There are actually 2 large cranes onsite, the taller of the two located
at the top of the tower is a Linden Comansa 21LC290 flat top crane,
with maximum load capacity of 18 tons. A very fast, smooth hoisting
winch is capable of hoisting at a speed of up to 228 meters per
minute. The hoisting drum has a capacity for 1280 meters of wire,
and the crane uses a special Lebus drum to ensure the very long
hoist wire rope will coil correctly. The crane is designed to handle
the wind loads at the maximum height of 325m, and internal
climbing sections enable the crane to climb 4-5 floors per climbing
movement, to stay ahead of the height of the main tower.
Located at the base of the tower, the Linden Comansa LCL310 luffing
jib crane (meaning the jib of the crane can move up and down) has
a maximum load capacity of 24 tons. It was erected with a maximum
height of 45.9 meters, and will remain in this configuration until the
end of the development. Its jib length (reach) is 60 meters, and can
load up to 3.2 tons at the end of the jib. Its main job is to support
the work of the 21LC290 on top from the ground. It is used to unload
the material from the trucks and to locate it on the spot where the
21LC90 can load it, or to place the material on the site to stock until
it is needed. This crane is in a single fixed position, but its 60 meter
long jib and large lifting capacity enables Bouygues-Thai to speed
up the construction schedule, therefore saving time and costs.
Operating the crane is a special skill. Each crane operator receives
special training and many have worked in this capacity for a long
period. Along with the operator, each lift usually requires a signaller
who directs what the crane is doing via radio and handsignals, 1-2
people at the bottom loading and another 1-2 people at the top for
unloading.
The crane comes with digital indicators that provide the operator
with important information such as the weight and the position of
the load (height and jib-length). In addition Bouygues Thai have
installed a camera in the cabin, enabling faster and more accurate
operation.