The swing motion bogie system for a freight car is more effective regarding the vibration damping effect than other freight car bogie systems while operating, and it is a bogie system that can travel up to 120 km/h despite being a freight car. Imported in 2006 in Korea and operated for more than 10 years in the domestic railway environment, the performance and maintenance efficiency have been proven compared to the existing welding bogies. As a result, the domestic demand will continue increasing in the future, but it is now dependent on overseas imports. In the long term, it is expected to cause problems such as loss of foreign currency and delay in procurement during maintenance. For this reason, development of the localization of the swing motion bogie system is underway, and it requires accurate performance analysis and validation of operating behavior characteristics because the bogie system is one of the main devices of the railway vehicles. Thus, in this study, we could confirm the suitability of the swing motion bogie system in the domestic operating environment based on the analysis of the operating behavior characteristics, the validation at the laboratory environment, and the operating test on the track.

The self-locking nuts that are used in high-speed railway-vehicle bogies and car-body connections are key components of the fastening system. These bogies and connection systems should withstand the high vibrations and shocks that are generated by high-speed operations. Since the first high-speed railway was developed, the antiloose nuts that are globally used in all of the high-speed rail-vehicle bogies and car-body connection systems are single-use limited to prevent nutloosening accidents during train operations. In this study, we developed a double reusable nut for the self-locking nuts of high-speed rail vehicles with a 100-% lifetime improvement. The proposed nut design was subjected to the KS R 9144 and NAS 3350 vibration-performance evaluation tests, and following the DIN 65151 method, a Junker test was performed for an impact-performance test. As the final step, a practical-application test was performed to assess the reusability of the proposed nut for which the self-locking nut of the HEMU-430X high-speed rail vehicle was utilized, and two reusability tests were subsequently carried out to evaluate the safety

Critical speed analysis was conducted for a active steering bogie prototype, developed to improve the curving performance of railway vehicles. The critical speed for the design concept was about 169.2 ㎞/h. To validate the analysis result, we performed a critical speed test for the prototype bogie using a roller-rig tester. The test results showed that the critical speed for the prototype bogie was about 165 ㎞/h. From the analysis and test results, The critical speed for the prototype bogie was determined to be 165 ㎞/h. Considering the maximum operating speed of the test vehicle is 100 ㎞/h, the prototype bogie is considered stable.