ENGINEERING JUNE 2019 13BEARINGS
Bearings for rehabilitation
projects
Schaeffler’s specialists are not only
focused on new projects but also on
the rehabilitation or extension of existing
bridges such as the “Botlek” vertical lift
bridge in Rotterdam, which has had four
freeway lanes added since 2015. This
bridge across the Maas River is regarded
as one of the largest lift bridges in the
world. Massive electric motors via cables
raise the two centre parts of the bridge
within 109 seconds, 20 times a day.
The bridge elements consist of some
10,000 tonnes of steel, concrete and
asphalt – their weight is comparable to
that of the Eiffel Tower. However, a year
after the bridge was opened, experts
noticed strange noises and vibrations.
The original bearings in the 67 pulleys for
the counterweight cables were not able
to withstand the loads – a challenge that
ideally suited Schaeffler. Using its Bearinx
design calculation software, Schaeffler’s
experts from Schweinfurt and Höchstadt
were able to calculate the exact position
and type of bearings that were required
to handle the huge loads of the movable
bridge elements. Afterwards, every
pulley was refitted with a specifically
designed double-row cylindrical roller
bearing, each with an outside diameter of
almost one metre and a weight of 800kg.
Located some 2,000km southwest
of Rotterdam is the “Puente de Rande,”
a cable-stayed bridge that, since 1981,
has connected the towns of Redondela
and Moaña in the Spanish region of
Galicia. With a length of 1,604 metres, a
main span of 401 metres and two pillars
with a height of 118.6 metres, it was
the first of its kind to be extended by
two additional traffic lanes. Considering
the surroundings and design
characteristics, Schaeffler Iberia installed
140 maintenance-free spherical plain
bearings with Elgoglide coatings. These
ensure that the six lanes and the bridge
are securely held together while 50,
vehicles travel across it each day.Cylindrical plain bushes
Many different types of bearings
are suitable for bridge applications.
Cylindrical plain bushes, for example,
are particularly suitable for small swivel
movements but also allow axial motion.
As a result, these bearings are ideal for
applications such as those found in the
upper suspensions of the supporting
cables of cable-stayed (suspension)
bridges. Plain bushes from Schaeffler
have high dynamic load ratings, deliver
long service life and require minimal or
zero maintenance.Radial spherical plain bearings
In order to limit the forces of dynamic
motion up to and including earthquakes
in bridges and other architectural
structures, large-size shock absorbers
are used. These can be suspended from
radial spherical plain bearings. These
components combine the strengths of
cylindrical plain bushes with the ability
to compensate for swivel movements
and tilting.
In contrast to the upper suspensionpoints of the supporting cable, the
lower mountings must also absorb the
multi-directional pivotal movements
emanating from the road. This means
rather than using plain bushes at the
top, the more agile radial spherical plain
bearings are used.Radial spherical rolling bearings
Radial spherical rolling bearings are
ideal for systems with a greater range
of motion such as bascule and swing
bridges, where high radial loads occur
in combination with axial loads. With a
much more compact design than other
rolling bearings, these are extremely
strong and withstand extremely high
loads. Alternatively, the folding and
swiveling elements can be equipped
with radial spherical plain bearings.Radial spherical plain bearings
with high dynamic load ratings
and special coatings
The hydraulic cylinders in bascule and
swing bridges must move extremely
high loads. Radial spherical plain
bearings with high dynamic load
ratings and special coatings from
Schaeffler ensure the required agility
and maximum actuator reliability- even in the harshest of ambient
conditions. Furthermore, these
radial spherical plain bearings can be
installed in the folding and swiveling
elements as an alternative to radial
spherical rolling bearings.
http://www.schaeffler.comBotlek Bridge
Rotterdam