a pan-European operating Train to Speed-up the Homologation of a low noise Brake System with LL Brake Blocks

EuropeTrain - a pan-European operating Train to Speed-up the Homologation of a low noise Brake System with LL Brake Blocks

Johannes Gräber, Torsten Hilker, Dr. Stefan Dörsch
DB Systemtechnik GmbH, Minden, Germany

The project EuropeTrain

Based on the main conclusions of the synthesis report [1] UIC started the EuropeTrain project which aimed to investigate the use of noise reducing LL brake blocks regarding LCC and running stability of freight wagons. Following a German initiative in the 9th meeting of the Directors General of the European Railways in Berlin on September, 5th 2009, 29 railways, the sector organisations CER, EIM and UIC and 8 industry partners supported this pan-European and unique project to speed up and improve LL brake block testing in operations. A special test train has been subjected to an intensive test and monitoring programme throughout Europe.

The train consisted of about 30 wagons, provided by several European railways to achieve a best selection of representative European wagons types and ran throughout Europe only for the in-service testing of LL brake blocks.

The path of the EuropeTrain was defined in different Loops, each representing certain operational, topographic and/or meteorological conditions. All operational conditions relevant for Europe had to be covered, e.g. running on different gradients with different operational modes, arctic winter areas and high temperature zones.

The duration of testing in service was planned to be at least one year taking into account all climatic seasons. In addition a mileage of minimum 200,000 km needed to be achieved, to collect enough data to allow at least to recommend longer inspection intervals than defined so far in the UIC “Usage guidelines for composite (LL) brake blocks” [2].

The train finally started in December 2010 with a first run on the Scandinavian Loop to Sweden and ended with a summer mixed Loop to the mountains of Austria combined with a one week run to Hungary.

After almost two years of service all over Europe, the operation of the train came to an end in September 2012 with a mileage of over 200,000 km within 16 runs, covering in reality all operational, topographic and climatic conditions relevant for Europe.
This final project report [3] summarizes the most important results along the original main goals of the EuropeTrain, which were among others

  1. to serve as a tool to accelerate the solution process for the problem of equivalent conicity degradation by reaching enhanced understanding of equivalent conicity limit values and effects on running behaviour (UIC SET 04/TTI)
  2. to deliver field experience on the wear of block and wheel with LL blocks (LCC) in the short term and of high quality.

Development of the equivalent conicity

EuropeTrain achieved a very good insight into the development of equivalent conicity under the given test conditions. The reduction of the nominal flange thickness, so the usage of a wheel profile with a flange thickness less or equal 30.5 mm (as it was already foreseen as a mandatory requirement in the Usage guideline [2]) is an important basis for the successful operation with LL-blocks. All following conclusion are drawn on this basis.

The following observations can be derived from this analysis:

  • Wagon type, loading history and use in the specific circumstances in the various runs have a significant influence on wheel wear and equivalent conicity.
  • The P10 cast iron blocks give the lowest increase in equivalent conicity per 100,000 km and seem to be very “stable” (low dispersion, no important increase in a short mileage). With high mileage (>100,000 km), there is almost no more increase of equivalent conicity. It seems that the evolution of equivalent conicity tends to an asymptote.
  • The C952-1 blocks give an equivalent conicity growing faster than with P10 cast iron blocks. The increase seems to be predictable with low dispersion between sequential measurements and different wagons. The increase of equivalent conicity remains linear, even for high mileage (no asymptote).
  • Averagely, the use of IB116* blocks results in an equivalent conicity growing little faster than with P10 blocks but lower than with C952-1 blocks. The increase of equivalent conicity remains linear, even for high mileage (no asymptote). However the behaviour of wagons with IB116* is sometimes less predictable with high changes between sequential measurements and different wagons in some cases.

Conclusions of the UIC 518 tests and the continuous datalogger measurements

The qualitative link between equivalent conicity and running stability reveals a decrease of stability if equivalent conicity increases. The quantitative link between EC and stability is not so well known, as stability is driven by plenty of other characteristics:

  • bogie and suspension characteristics. The influence of this is emphasised by the fact that freight wagons have a large number of dispersions in these parameters, such as friction coefficient, spring heights, geometry of elements
  • loading of the wagon
  • adhesion coefficient between rail and wheel.
    One of the main objectives of the EuropeTrain is to improve the knowledge of this quantitative link.

It can be determined that:

  • an equivalent conicity of 0.2 seems to be pretty usual on rail inclination of 1/40 and this doesn’t expose freight wagons to instabilities
  • the stability measurements during the runs and in the UIC 518 tests showed that wagons with higher equivalent conicity show a different and undesirable running behaviour to that known from the existing services (hunting behaviour with very high accelerations). However no exceeding of safety limits of UIC 518 has been recorded with an equivalent conicity lower then 0.4 and running gears accepted for 120 km/h.
  • comparison of the running stability during runs with running stability during UIC518 tests has shown that (for the same wagon) the measured acceleration level during runs is lower than during the UIC518 tests. This proves that UIC518 tests have been able to simulate worst case conditions.

It is expected that the different kind of vehicles will have different levels of acceptable EC values to ensure safe running behaviour.

With the results of the first three UIC 518 running tests (including all different wagon types used in the EuropeTrain) it can be summarised that the running behaviour of all tested wagons based on the existing contact conditions comply with the safety limit values specified in UIC 518 up to the maximum test speed of 120 km/h which proves a save running up to an operating speed of vmax = 110 km/h (test speed – 10%).
The results of the fourth UIC 518 stability test show that the running behaviour of the tested wagon types Eas and Remms based on the existing contact conditions comply with the safety limit values specified in UIC 518 up to a maximum operating speed of vmax = 120 km/h (test speed 132 km/h).

If the equivalent conicity is higher than 0.4 (real measured wheel profile linked with the theoretical rail UIC 60E1 with 1:40 inclination and a gauge of 1,435 mm) the measured acceleration levels are exceeding the accepted limit of the UIC leaflet 518 in some parts of the line. The combination of worn wheels and worn rails results in principle in higher real equivalent conicity levels - partly higher than 0.8 in some sections based on the track conditions.

It can be concluded that for the whole wagons that were on EuropeTrain, an equivalent conicity of 0.4 (real measured wheel profile linked with the theoretical rail UIC 60E1 with 1:40 inclination and a gauge of 1,435 mm) is dynamically safe for operating speed of 100 km/h. Safety is also proven for an operating speed of 120 km/h except for wagons with bogie type Y25 with non-suspended side bearers.

Block and wheel wear

To fulfil the second main goal - to deliver field experience on the wear of block and wheel with LL blocks (LCC) in the short term and of high quality – brake block and wheel wear were monitored very closely in the project. A huge data base was achieved that can serve as a very good basis for further LCC analyses.

Summarising the results, the following can be stated:

  • The block wear in general is mainly influenced by the homogenous nature of the train (i.e. mix of cast iron and composite brake blocks).
  • Both block and wheel wear depend strongly on the load spectrum of the wagon in the different runs (i.e. topography, loading status, design of the wagon, braked weight).
  • LL-blocks do have a smaller wear than cast iron blocks. The sintered block C952-1 shows under loaded conditions only 21% of the block wear of cast iron, IB116* shows 51% of the value of cast iron.
  • For a more accurate calculation of the block wear, fitting to the conditions of the different operators, the data of EuropeTrain will be analysed and provided in more detail. So, every operator will be able to adapt the data to his special traffic and calculate the special LCC. A project concerning the analyses of the LCC is started within UIC.
  • The main parameters influencing the LCC of wheelsets are the wheel (tread) wear (caused by rolling contact between wheel/rail and by the application of the brakes), the reprofiling interval and the removal of wheel material due to the reprofiling process (cutting depth).
  • The use of LL-blocks increases the wheel wear rates. Wear rates are strongly depending on the loading conditions of the wagon and vary strongly between the runs and wagon type. The main wear rates determined over the whole duration of the project, expressed in the change of the flange height (ΔSh) are
Wheel wear rate (ΔSh) [mm/100,000 km]and in % to CI
CI empty CI loaded C952-1 empty C952-1 loaded IB116* empty IB116* loaded
0.7 100 % 0.9 100 % 0.8 109% 2.2 237 % 0.8 109 % 1.8 194 %

Table: Averaged over-all wheel wear rates of EuropeTrain operation

  • The average wheel wear (ΔSh) rate about all brake blocks and all loading condition is 1.35 mm / 100,000 km.
  • The reprofiling interval will differ for the different brake block materials and the different service condition. In comparison with cast iron brake blocks in general a medial reduction of the reprofiling interval is expected, a detailed forecast is not possible. Based on the wheel wear rate a reprofiling interval for LL blocks between 150,000 and 250,000 km is realistic.
  • The average evolution of the flange thickness for the different brake block types differs in a small range. All brake blocks, except C952-1, shows a similar behaviour like cast iron brake blocks with a slightly decrease of flange thickness. Based on these results the cutting depth during reprofiling will be on a comparable level. For C952-1 the cutting depth could be a little bit lower.
  • Summarising all results it is possible to use the data of EuropeTrain as a basis for ex-tending today’s very restrictive inspection limit value of 0.23 and inspection intervals of 50,000/25,000 km (see [2]).

Actual status of homologation of LL-blocks

Based on the results of EuropeTrain, which are summarized in [3], UIC elaborated new inspection limits and inspection intervals regarding the monitoring of the wheel profile. These new rules are written down in the actual version of the usage guideline for composite (LL) brake blocks [5], which can be downloaded from the UIC-website.

As general requirements, which can be adapted by a ECM with a corresponding risk assessment, it is stated, that in case of using LL-blocks

  1. The equivalent conicity (a relevant parameter for the wheel/rail contact conditions) shall not exceed the value of 0.40 .
  2. The wheel profiles shall be monitored at regular intervals.

Furthermore the guideline is giving proposals how to ensure the fulfilment of these requirements or even under which conditions the monitoring can be skipped. For ex-ample the actual inspection intervals are now expanded to 100.000 km/50.000 km, see [5].

As a consequence of this work, UIC stated the homologation of the two LL-brake blocks of the types IB116* and C952-1 on May, 1st for standard freight wagon with 920 mm wheel diameter.

On June, 1st, the 1:1 exchangeability of these two blocks under certain boundary conditions was added, on the basis of the report B126.13 DT 440 [4].

The ERA took over these technical data in its Technical Document 02, also since 1st of june 2013, so that these informations are available now in the whole freight wagon sector.

With these important milestones, the basis is made for a larger scale retrofitting of most of the existing freight wagon fleet, which is considered to have a big impact on the noise reduction in railway freight traffic within the next 10 years.


  1. UIC B126 RP 36 - Use of composite brake blocks in freight wagons - Summary report on LL brake blocks (May 2009)
  2. UIC Usage guideline for composite (LL) brake blocks, 8th Edition, 01 July 2011
  3. UIC B126 RP 43 - Synthesis of the EuropeTrain operation with LL brake blocks - Final report (2013)
  4. UIC B126 DT 440 - Exchangeability of the LL-blocks IB116* and C952-1 with cast iron blocks (type P10) (May 2013)
  5. UIC Usage guideline for composite (LL) brake blocks, 9th Edition, 01 May 2013
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Thursday 4 June 2015