M. van den Berg
Torenkranen in de bouw
Report 2001.TT.5478, Transport Engineering.
Theoretically a tower crane is made up of three basic elements: an
undercarriage, a tower and a jib. These basic elements come in all kind of
variaties. All known variaties are showed using a block diagram. Combining
the different variaties of the basic elements, different kinds of tower
cranes can be made.
All possible versions of tower cranes which can be found in practice, can
be divided into two main classes: bottom slewing tower cranes and top
slewing tower cranes.
The slewing ring on a bottom slewing tower crane is situated on or just
above the undercarriage. All types of mobile tower cranes and fast-erecting
tower cranes belong the class of bottom slewing tower cranes.
The slewing ring on a top slewing tower crane is situated at or near the
top of the tower. These types of tower cranes can be subdivided into two
groups, according to jib-type. The first group consists of tower cranes
fitted with a saddle jib (also known as "trolley jib cranes"), the second group
consists of tower cranes fitted with a luffing jib or a fixed-luff jib.
All common types of tower cranes are showed, again using a block diagram.
An accurate description of all known versions, have made a clear view of the
(technical) capacities of all possible (standard) versions of tower cranes.
Beside the standard versions, so called custom-versions are also
available. Customers can make their wishes known to the supplier for
special applications for their tower crane. In this way, a "tower crane down
to size" can be designed (if necessary), manufactured and delivered. With
custom-versions almost everything is possible within the borders of the state
of the art.
One of the most imported things concerning tower cranes is modularity.
Both the tower and the jib are made up of modules. This makes transporting
as well as building up and breaking down the tower crane much more easy.
The modules are exchangeable as long as they are from the same
manufacturer. This is also the main reason why building contractors use
only tower cranes from one manufacturer.
Wind causes the most important external load on a tower crane. Work with a
tower crane can be continued until the wind force reaches about 8
Beaufort. It also depends on what load is being lifted (sensitivity of
(cross-) wind) and the feeling of responsibility of the crane driver.
Modern tower cranes are equiped with an advanced, modular drive for moving
the trolley up and down the jib and hoisting, slewing, displacing and
possibly luffing. Most of the driving engines are frequencymodulated. This
way hoisting work and driving the trolley up and down the jib in
particular will be controlled movements.
For choosing the right tower crane for a certain building job, no
checklist or what so ever is used by the people who have to make this kind
of decisions. These people are staffmembers of different divisions (such
as planning and equipment) of the building company. Usually the unique
situation of the building project requests a certain tower crane by
itself. Further the experience of the staff seemes to play a major role in
deciding what the best tower crane for a certain building job will be.
Another very important issue for the building contractor is what the
standing time should be for a tower crane on the building site without
standing too long or too short but standing long enough to do all (the
most of) the hoisting work.
After that a particular tower crane has been chosen for a certain building
job, the tower crane must be transported to the building site.
Transportation is done by using just a regular trailer, no special trailer
is designed for this matter. The modules of the tower crane are driven to
the building site and the tower crane will be built up straight away,
using a mobile crane (most of the times) for the hoisting work. A severe
(and statutory required) safety test will be made before the tower crane
can get into action. This test will be done using the checklist shown in
an appendix. This checklist will also be used when a tower crane has to be
checked again if its standing time is more then a year (periodical test).
Breaking down a tower crane goes the same way as building it up but in
In future the use of top slewing luffing jib tower cranes will increase.
The advantage of this type of tower cranes compared with other types is
the possibility of putting more tower cranes on a certain surface.
Furthermore this type of tower cranes are equiped with more powerful
driving gears (for the need of luffing). Therefor the building speed is
high which will significantly reduce the costs. The role of the bottom
slewing tower crane will also increase because of the fact that these type
of tower cranes are flexible, compact and rapidly available.
Tower cranes will be even larger and higher in future to decrease building
times and reduce costs. A good example is the recent development of a so
called "giant tower crane".
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