Field investigations into the performance of magnetic track brakes of an electrical multiple unit against slippery tracks. Part 2: Braking force and side effects

Abstract

Part II of the field investigations focuses on the braking force and some possible side effects of the frequent use of magnetic track brakes (MTBs) against slippery tracks. In part I, the adhesion recovery using MTBs along contaminated rails has been presented. Field tests have been performed with the permanent MTB of an electrical multiple unit (EMU) in a stabling yard. Three types of contamination representative of slippery tracks have been employed, e.g. water, leaves, and grease. Tests with dry ‘clean’ rails have also been performed throughout the testing to obtain a reference of the braking force in the speed range 0–40 km/h. Furthermore, the braking performance of the EMU in different braking modes is analysed under the tested conditions. The surfaces of the brake shoes and the rails have been examined to analyse possible changes during the testing. The profile of rails and the mass loss of the brake shoes have also been measured in the tests to quantify the wear caused in the tests. Moreover, the possible negative effect of a passing MTB on the electrical insulation of an insulated rail joint has been examined by means of electrical measurements and visual inspection.