THE VOSSLOH ELASTIC
COUPLING
The railway network in our
country has used, until 1990, the indirect coupling of the rail to the sleeper: the K
coupling. Over the years, this method has proved insufficient, which prompted this use of
other variants of elastic coupling - E1, E2 and E5. The biggest advantage of this type of
coupling is that is calls for operating expenses that are much lower compared to other
couplings. To demonstrate this, we will give the list the main characteristics of elastic
couplings that contribute to lower operating costs:
a) amortisation of shocks transmitted by the rolling stock, leading to
a lesser impact on the grindstone prism and the embankment. This slows down the
degradation of the track, increases time spans between inventions, and therefore reducing
maintenance costs;
b) elastic couplings require very little effort to be brought to a
normal operating regime or even eliminate this need entirely;
c) they grant a high resilience to longitudinal deflection of the
track, which is very important for the welded line, leading to fewer hazards of
deflections under high temperatures;
d) a very low consumption of metal per kilometre of track, compared to
the other types of couplings, by eliminating metal plates;
e) a very good behaviour in areas with high declivity and with rail
displacement;
f) is mandatory for high speed lines;
g) has a low influence on the environment, as the noise produced by
travelling trains is lower compared to other types of couplings.
The E1 elastic coupling combines the qualities of indirect coupling (K)
with those of elastic couplings - by replacing the rigid “K” claw with the E1
elastic pin. Elastic deflection, however, is low (3-4 m).
The E2 elastic coupling is based on two supports made of OL 42 steel
and was designed for the type 49 rail. The rail is lodged directly on the sleeper via a
rubber plate, and the main elements that ensure an elastic coupling are the elastic clams.
They are mounted to the sleepers via elements that are buried into the sleeper. The E2
clam provides a 6 mm elastic deflection, and was introduced to the railway network between
1980-1990.
The E5 elastic coupling resembles the E2, but OL 42 supports are
replaced by polyamide ones, and elastic clams are shapes as two steel blades. This
coupling, too, was abandoned because failed to provide safety in operation and was
expensive.
Analysing all these characteristics, which had little advantages for
the Romanian railway network, specialists oriented toward a new type of elastic coupling,
the Vossloh coupling, which is also known under the name of Skl 12. The most has
been introduced to the CFR network in areas with ramps, slopes and curves of various
radii. The Skl 12 elastic coupling procedure replaces the claw with an elastic wire; using
the existing vertical volume and eliminating the spring ring, bolts are tightened to a
specific torque, via a disk. The wire (made of 13-mm spring steel), is shaped into a W,
and laid on the supporting metal plate. Thus mounted, it allows the lower loops to fix the
plate, while the open branches support the foot of the rail. Tightening is done with a
bolt, via a disk.
The Skl 12 coupling system is used to mount rails onto sleepers made of
wood or concrete, for lines construction, rebuilding works, repairs or maintenance of
existing track.
It can also be used for rails with or without joints, ensuing
elasticity around 12 mm, which leads: less wear on the tracks and rolling stock, greater
traffic safety, and comfortable travel.
The constructive shape of the clam allows the central branch to hold the rail
in operation even if the lower branch is broken.
Maintenance for the Skl 12 elastic coupling is reduced, because the
clam maintains, in time, the same pressure, requiring less maintenance workload.
Another type of elastic coupling is the W 14 system, also made by the
German firm Vossloh, which improves on the Skl 12 system. This coupling has been adopted
by the CFR - SA for rehabilitation and modernisation works on the 4th
Pan-European Corridor, with the following advantages:
- low workload and
expenses;
- very good behaviour
under heavy traffic and high speeds (250 km/h);
- does not require
restraints during operating periods;
- does not have
problems with the track gauge;
- can be pre-assembled
in sleeper factories;
- does not require a
high precision in building the grindstone bed, as the difference between the rail and the
sleeper can be made for by unscrewing the rod;
- allows progressive
changes of the track gauge, up to + 10 mm (the same of type of sleeper can be used both in
the alignment, and in curves with R > 251 m)
- a very good behaviour
in longitudinal declivity of the track;
- allows the
replacement of any broken element;
- includes an
anti-vandalism device;
- allows the desired
tightening torque.
The Vossloh elastic coupling is used by many railway administrations in
Europe, and sales figures are on a constant rise.
Starting with October this year, the Vossloh elastic coupling will be
mounted on the Bucharest - Ploiesti portion. The sleeper will be made in the country, and
the manufacturer will decide whether the other components will be manufactured here or in
Germany.
Because of its advantages, the Vossloh coupling has been used on 475 km
of track, and its use will continue to expand.
Anton Vladescu
Magdalena Stanciu
