In this investigation, a nonlinear air suspension system model that accounts for the coupling between air springs, leveling valves, and differential pressure valves is developed and integrated into general-purpose multibody dynamics computer algorithms. It is demonstrated that the proposed model can capture highly nonlinear air suspension characteristics resulting from the coupling with leveling and differential pressure valves, and good agreements are obtained between the numerical and on-track test results. Furthermore, the effect of flow characteristics of leveling valves on the wheel load unbalance on spiral curve sections is discussed. The numerical results obtained by the proposed model clearly indicate the importance of modeling the nonlinear flow characteristics of the leveling and differential pressure valves for assessing the vehicle safety in low speed operations on a small radius curved track.

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The fatigue design criterion for members of cast steel is not specified in the design standard of railway bogie frames in Japan. The objectives of the present study involve clarifying the fatigue property of cast steel used in railway bogie frames and proposing a fatigue design criterion for members of cast steel. Fatigue tests are conducted on test specimens with casting or machined surfaces under axial loading or plane bending. The results indicate that the fatigue strength of specimens with casting surfaces exceeds that of specimens with machined surfaces. The fatigue strength under plane bending significantly exceeds that under axial loading. The results are attributed to differences in the locations and geometries of cast defects where cracks originate. A fatigue design criterion for members of cast steel is proposed by the statistical evaluation of fatigue data. Furthermore, the validity of the proposed criterion is demonstrated via a full-scale fatigue test of bogie frames with members of cast steel.

There are many problems in sharp curves negotiation such as large lateral force, squeal noises and excessive wear of wheel flange and rail gauge corner. To solve these problems, single axle steering bogie (proto type: FS576) has been developed by Tokyo Metro and Nippon Steel & Sumitomo Metal Corporation. The authors confirmed good curving performance by FS576 on the result of field test. Therefore, Tokyo Metro adopted this newly single axle steering bogie (production type: SC101) for new series 1000 in Ginza line. SC101 improves lateral force, noise level, and lateral acceleration of rail in passing curves. In this paper, the design concept and outline of steering bogie SC101 for series 1000 are described. And the curving performance of SC101 is evaluated based on the result of field test and commercial service.

Fatigue design criterion for members of cast steel is not specified in the design standard of railway bogie frames in Japan. The objectives of the present paper are to clarify the fatigue property of cast steel used in railway bogie frames and to propose a fatigue design criterion for members of cast steel. Fatigue tests are conducted on test specimens with casting or machined surfaces under axial loading or plane bending. It is clarified that the fatigue strength of specimens with casting surfaces is higher than that of specimens with machined surfaces; the fatigue strength under plane bending is extremely higher than that under axial loading. These results are attributed to differences of locations and geometries of cast defects where cracks originate. A fatigue design criterion for members of cast steel is proposed by statistical evaluation of the fatigue data. Moreover the validity of the proposed criterion is demonstrated by the full-scale fatigue test of bogie frames with members of cast steel.