Dynamic test and characteristics analysis of rack railway under curve passing conditions on large slope line

Rack railways are extensively employed in mountainous areas due to their exceptional gradient-climbing capabilities. However, systematic experimental investigations on the dynamic behavior of rack systems on large slope curved tracks are still lacking. Therefore, this study conducts a field test to investigate the dynamic interaction mechanisms and vibration response characteristics of rack vehicle-track coupled systems under curve passing conditions on large slope line. Firstly, vibration accelerations of critical components, wheel-rail forces, and rack stresses were measured on the test line. Then, time-domain and frequency-domain analysis methods were subsequently integrated to reveal dynamic coupling effects between wheel-rail contact and gear-rack meshing. The results indicate that complex coupled vibration characteristics in wheel-rail forces are generated. There are differences in the load distribution between the inside and outside of the rack, and the rack has eccentric wear phenomenon. The gear-rack meshing excitation has additional influence on the lateral vibration of the carbody. The vibration of gearbox and motor is mainly caused by the gear-rack meshing. This study has important engineering significance for improving the operational safety and structural durability of rack railways in the large slope curve section.