Braking - Ventilation of friction test benches

The present document describes the chosen method and tests carried out on the friction test benches of UIC railways to compare then harmonise the efficiency of ventilation systems specific to each bench.

Two series of tests were performed.

The first series established that significant differences existed between the benches and modifications (settings or geometry) were prescribed.

A second series of tests performed with the modified benches showed that it was possible to harmonise ventilation power by using cooling time constants as a basis.

This harmonisation of test benches makes it possible to perform comparative braking performance tests on different benches.

Subsequently the method used to quantify the ventilation power of benches can be applied to wagons in tests, which would make test conditions on benches similar to the conditions of service tests.

In order to enable cooling time constants to be determined for benches which can only be used with disc brakes, comparative tests were executed with disc brakes in 2011, the results of which were incorporated into the present (second) edition of this report.