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 reduction unit is one of the most important components in railway cars, due to the transmission of torque from the motor to the wheels. Faulty reduction gears in high-speed trains result from excessive wear on the gear or damage to the gear. These types of gear defects have a significant effect on high-speed rail operation and safety; thus, a diagnosis system for the reduction unit is needed. Vibration diagnosis technology is one of the most effective diagnostics. In this paper, the vibration parameters of a reduction unit were evaluated during a driving-gear test and a full-vehicle test, using kurtosis and the crest factor. These tests were performed under normal operating conditions; a specimen tester was used to diagnose problems in defective gears.

The gear-reduction units of Korean high-speed trains consist of a motor reduction unit, an axle gear box reduction unit, and a tripod joint shaft. A reduction gear unit is a gearbox used to reduce the rotational speed of the input shaft to a slower rotational speed on the output shaft. This reduction in output speed helps to increase torque. Defective reduction gear units in high-speed trains are caused by damage to the gear or by gear fatigue. To diagnose potential problems, it is important to know the vibration characteristics of the reduction gear units. In this study, we analyzed the vibration characteristics of reduction gears under various conditions. The test setup included a ull-scale test rig to evaluate reduction gear under both normal and extreme operating conditions.