Influence of coupler behavior on braking safety of middle locomotives of heavy-haul train
In order to accurately simulate the runtime behavior of the coupler and buffer systems, the dynamics model is improved by adopting polygonal contact model, which can accurately simulate the deflection behavior of couplers as well as the relative motion of coupler connection surface; then integrated with locomotive longitudinal dynamics, simulation analysis is conducted on the running safety of middle locomotives and dynamic response of the coupler and buffer systems under emergency braking condition. Results show that longitudinal impulse has a large influence on the runtime behavior of the coupler and buffer systems, and the deflection of coupler under compression exerts negative impact on lateral dynamic performance of locomotive, so coupler stability under compressive force should be attached great importance to; due to the friction surface in coupler tail, flat-pin coupler has better stability under compressive forces on straight lines than round-pin coupler, but this depends largely on the friction state in the coupler tail. Therefore, it is recommended to strengthen the inspection on friction surface in flat-pin coupler tail so as to avoid the function failure of the friction surface; as longitudinal impulse is mainly reflected on continuously changing pulling and compressive impact, coupler connection surface usually fails to conduct an effective constraint on the deflection. Accidents caused by decoupling are more likely to happen with a big track irregularity, grade change point and coupler height difference. Therefore, it is proposed that vertical anti-off stopping devices are added to avoid the occurrence of such accidents.