ENGINEER TO ENGINEER
500t bridge crane
for uneven loads
Kranbau Köthen has built a crane with a
lifting capacity of 500 tons and a special
design, whereby the weight distribution
in two axes can be finely balanced using a
special shaft end support.
The process crane, for an ABB plant in
Sweden that manufactures transformers,
was commissioned to be able to
handle increasingly large loads. The
predecessor’s maximum lifting capacity
was 300t.
This weight increase required the
investment in a new crane, and Kranbau
Köthen was commissioned for its
development and production. A special
feature had to be considered because
the centre of gravity of the transformers
is distributed very unevenly. The crane
therefore must adapt accordingly to
ensure smooth and delicate lifting and
lowering of the heavy load.
Based on these requirements,
Kranbau Köthen engineers developed a
crane and a special heavy-duty shaft end
support (pictured, right). It consists of
two carriers, whose spacing is changed
by lead screws. The two attachment
points on each carrier are also adjustable,
so that each of the four winches can be
positioned separately. The transformer
can therefore always be attached in such
a way that its weight is evenly distributed
over all four attachment points. In
addition, the entire shaft end support is
rotatable. It is suspended on a very large
load-measuring bolt.
Other special features include three
auxiliary strokes, each with a loading
capacity of 20 tons, and an extraction
system on the trolley travelling winch.
This is to protect the transformer from
abrasion debris during the assembly
process.
The cables are guided on the crane
girder to the 30-metre-wide bridge using
a standard igus E4 4040HD energy chain.
In this case, the extras included double
strain relief and a floating moving end, to
compensate for any lateral misalignment
and wheel clearance in the trolley drive.
Because of the benign environmental
conditions (normal climate, no high travel
speed), cables with PVC outer jackets
can be used in the ABB crane. They are
said to be more cost-effective than TPE
cables and also generate less abrasion
debris than PUR jackets (ensuring
cleanliness). The electrical connection
between the two shaft end supports,
which can be moved towards each other,
is also ensured with energy chains and
chainflex cables from igus. Here, E4
e-chains are also used.
Following a factory acceptance test at
the German site, the crane was loaded on
several flat-bed trucks and transported
to Sweden. Part of the route was by sea,
so ferry loading of the fragile cargo was
inevitable. After installation by Svenska
Lyft, ABB carried out a final test and
final inspection; 625 tons of test weight
(corresponding to 125% of the maximum
nominal load) had to be provided for the
acceptance test. Tests of the emergency
stop device at full speed were also part of
the test series.
Maik Stern, head of production at
Kranbau Köthen, says: “After all, as a
globally leading technology company,
ABB is also a specialist in the field of
crane technology and therefore also a
critical customer.”
32 www.operationsengineer.org.uk May 2019
/www.operationsengineer.org.uk