Mr Marc Antoni, Director of UIC Rail System Department, introduced the 100th edition of the B126.13 meeting and underlined the importance of this Working Group which was one of the key players for the replacement of cast iron brake shoes with composite material.
The creation of this working group took place in the late 1990s when Mr Raison, former chief engineer of the SNCF braking department, was approached by Mr Heinisch, a former member of the board of DB and responsible for research and development within DB with the aim of reducing noise emission caused by freight traffic by 10 dB.
The first meeting of B126.13 was held on 6 and 7 January 1999, following a decision taken by the SC5T in June 1998.
With regard to the longevity of the service life of railway material the objective of this Working group was twofold:
- Development of a brake block with high friction level to be used on newly-built Rolling Stock in place of the formerly used cast iron brake block (the so-called “K” block)
- Development of a brake block with a friction coefficient similar to cast iron allowing the replacement of cast iron brake blocks on existing freight wagons
The coefficient of friction of cast iron is not constant but depends on both application force as well as speed. As it was more difficult to develop a brake block with these requirements than a brake block with a constant coefficient of friction, the work in the beginning was dedicated to the development of a “K”-block allowing the design of “quiet” new wagons. This first phase of the project ended in 2003 with the system approval of K blocks. From 2004 onwards new wagons were equipped with composite brake blocks.
To achieve an audible reduction of the rolling noise emitted by wagons a minimum of 75% of the wagons in a train have to be equipped with composite brake blocks. With the slow renewal rate of the freight wagon fleet (useful lifetime of freight wagon is between 30 and 35 years) a reduction of the noise would only become evident after 15-20 years.
This is why after the system approval of the K block the WG continued their efforts on the development for the so-called “LL” blocks with the goal to find a solution to replace cast iron blocks in existing wagons without any other need for modification.
To keep in mind the complexity of the task a few requirements need to be met:
- Identical braking performance under all operational circumstances (dry, wet, snowfall, long inclines)
- Thermal protection of wheel in case of brake failure
- No negative influence on running behaviour (equivalent conicity)
- Faultless function on track circuits
- LCC not higher than cast iron with regard to the difficult economic situation of freight transportation on rail
Finally, in 2014 after numerous tests on dynamometers and on tracks on long alpine inclines as well as under arctic (or extreme weather) conditions, the system approval of LL blocks was achieved allowing the 1:1 replacement of cast iron brake blocks in existing rolling stock.
But the work of the WG is not yet over. A number of persistent problems (exchangeability of K-blocks, braking behaviour in winter from low initial speeds in shunting yards, clear definition of threshold between S- and SS-brake) are still awaiting a solution.
Since the beginning the WG has published 42 technical reports and documents and five new editions of Leaflets.
During the meeting six presentations were shown giving an overview over the work during the past 20 years as well as a perspective on future tasks and objectives.