SAFETY EVALUATION OF WELDED STRUCTURE BOGIE FOR FREIGHT CAR

초록

This study was aimed at evaluation life for the end beam of welded type bogie. Bogie is the core part that exerts an important effect on the passenger safety and running safety. There are two types bogie. One is cast iron type , the other is welded type bogie. The maximum speed of the cast iron type bogie limited to 90 km/h. The maximum speed of the welded type bogie limited to 120km/h. So, if one cast iron bogie was to be formed in one formation of the cars, the whole maximum speed limited to 90km/h. For the solution of this problem, the speed- up research of the cast iron bogie is on progress. For the speed-up of the freight car, a welded type bogie was developed in 1993 year for high speed(120km/h), and practical used in 1999 year. Some bogie frames manufactured in 1999, 2000 year have the fatal problem. Three or four years later, the cracked end beam among them have discovered in 2002, 2003 year. The crack situation of the end beam have a bad effect on brake system. In that case, the cars would be in danger of derailment. Main line real tests were performed at Kyeong-Bu line, Young-Dong line. The stress of main positions for bogie frame was measured. At this time the tests were performed for the three types bogie. The first is the existed bogie frame, the second is the bogie frame of the end beam reinforced and the third is the bogie frame of the torsion-free brake shoe holder hanger attached to check the torsion in brake load. The fatigue life is calculated by measuring the changing stress. It is estimated that the improved car which end beam reinforced is safe within the car permitted life(25 years)"