Wheels - Thermomechanical loads on small-diameter wheels braked with composite brake blocks

Given the forecast replacement of cast iron brake blocks with composite blocks as part of an initiative driven by the EU directive on railway noise abatement, the UIC designed a series of bench tests to reproduce braking incidents, with a view to approving brake blocks in 2Bg configuration on 920mm diameter wheels, and the relevant acceptance criteria.

When composite brake block requirements are met, wheels may be placed into service, after a braking incident, without any extra supplementary protective measures. If the aforementioned requirements are not satisfied, the brake block must be discarded, or can only be placed into service when accompanied with special maintenance instructions.

Extra tests were conducted to see if results obtained in 2Bg configurations on a 920 mm wheel were transposable to other configurations and smaller wheel diameters.

With the current level of knowledge, the overall level of safety is at least the same (GAME) for the reference configuration in RP 23 (2Bg with a 920 mm wheel) and the tested configurations (2Bg and 1Bg on wheels with nominal diameter of 840, 740 and 680 mm).

 When the results for exceptional load tests conducted in accordance with RP 23 are satisfactory, the tested brake block can be used in revenue service in any configuration without supplementary maintenance requirements.

However, if the block fails the test, the manufacture may ask approval for specific application only. This report contains the relevant test conditions and acceptance criteria for this special approval.