Dynamic Analysis Of Urban Mass Transit Vehicle Using Unsymmetric Bogies

The curves of urban mass transit usually are small and it makes the wheelsets wear rapidly, intimidates the safety of vehicles and increases the upkeep of rails and vehicles. The structure of bogie influences the dynamic performance directly, so it is need to develop new type bogies to improve the curve passing performance and decrease the wear of the wheels.The prime suspension of the bogie influences the dynamic performance directly. The primary longitudinal suspensions of the traditional bogies of urban mass transit usually are symmetric, being the steering wheelset the lateral force and the attack angle between wheel and rail of the front wheelset are bigger when it is passing through curves. On the basis of the foreign advanced experience, bogie with unsymmetric suspension is taken into study to improve the curve passing performance. The academic result shows that the equivalent bending stiffness of symmetric bogie will be maximal when the sum of longitudinal suspension stiffness of the front weelset and the rear wheelset is a fixed value, and it will make against to steering. When the longitudinal suspension stiffness of the front weelset and the rear wheelset are arranged unsymmetrically the equivalent bending stiffness will decrease and it will make for steering. Models of bogies with unsymmetric suspension have been set up and analysed by SIMPACK dynamic analysis software. The result shows that the bogie with the longitudinal suspension of the front wheelset flexible position will improve the curve passing performance and the stability of the bogie will be as usual.It is known that the independently rotating wheels allow the two wheels on the same axle to rotate independently from each other thus there aren't longitudinal creep force, at the same time the longitudinal creep force of the rear wheelset of the traditional bogie will holdback the front wheelset to steering. Using independently rotating wheels instead of the rear wheelset of the traditional bogie ,the lateral force of the front wheelset will decrease .Dynamic calculating mode is made and the results of numerical simulation validate that the bogie of independently rotating wheels for rear axle can increase critical speed and when it is operate on small curve it can reduce lateral force. Because of the bogie with independently rotating wheels for rear axle can increase critical speed, ways to decrease longitudinal stiffness of prime suspension, axle distance can improve the curve passing performance of the bogie of independently rotating wheels for rear axle.The dynamic analysis of unsymmetric bogies provide proper theory if unsymmetric bogies would be developed.