The Study On Method To Enhancing Steering Capability Of Independently Rotating Wheels

With the development of urbanization and the population increasing in city, the mass transit has become the mainly public traffic mode in metropolitan. Because having the advantage of getting on and off easily and lower cost of infrastructure, the Low-floor LRT has been accepted in many Europe cities.The key to realize the low floor in LRT vehicle is to decrease the height of wheelset axle and guarantee the gateway continuously. The way to solve this problem is to use the independently rotating wheels (IRWs). Because of no need to rotate, the axle of IRW can make to crank shape and even cancel it.Comparing with the conventional fixed wheelset, the IRW don't engender longitudinal creep force, so hunting won't occur and the stability of vehicle system is very good. But IRW loses self-steering capability of longitudinal creep moment, so its restoration capability and curving performance becomes worse. This shortage limits the use of IRW. How to improve the guidance and steering capability of IRW is a focused problem for a long time. The paper studies this problem and gives some efficient measures to enhance usability of IRW.For any running gear with IRW and passive suspension, the guidance capability of IRW originally comes from the gravity restoring force. The gravity restoring force lies on the contact angle of tread and wheel load. So the primary measure to improve the guidance capability of IRW is to use the special tread with high contact angle. The paper gives a new method to design the wheel profile of IRW. This method can automatically create the wheel profile in computer according the designed contact angel and given rail profile. The theory of this method and development process of the program in detail is introduces in paper and some examples are also given.Besides using the tread with high contact angel, the running gear with IRW and passive suspension is also needed to employ a specific radial mechanism. A novel force radial bogie - Coupled Single-axle Running Gear (CSRG) with IRW is introduced in paper. The CSRG is composed of two single-axle bogies setting on two...