Motion analysis on the EEF bogie unit with inclined wheel-axles realizing compatibility between running stability and curving performance

It is important for railway bogies to get compatibility between curving performance and running stability. Utilizing independently rotating wheels may be an effective solution. The EEF bogie proposed by Dr.Frederich in late 1980th shows good curving performance making use of the gravity restoring force generated by the tread gradient of independently rotating wheels. However, the bogie gives rise to a kind of hunting motion as the vehicle running velocity increases. In this paper, an effective modification of the EEF bogie which solves the hunting motion is mentioned. The solution is to incline both wheel-axles while adjusting the tread shape of each wheel. In this paper, the EEF bogie with inclined wheel-axles is firstly proposed and analytically evaluated by the MBD simulation. Since the newly proposed bogie has complicated structures, a precise modeling of the bogie is mentioned in detail. From the result of eigenvalue analysis, proposed bogie can dramatically improve the hunting stability as compared to the conventional EEF bogie. In addition, the proposed bogie has excellent curving performance in tight curve section equivalent to the conventional EEF bogie. As those results, it is possible to achieve both high speed hunting stability and curving performance utilizing the proposed bogie unit in the vehicle.