Steering Technologies Of Independently Rotating Wheels For Light Rail Vehicles

Since the independently rotating wheels (IRW) can remove the axle, the floor of light rail vehicle can be made quite low. But due to the cancellation of the rigid connection axle, then the wheels can rotate independently, which results in the lack of longitudinal creep forces and loss of steering ability for the bogie. In consequence, the IRW bogie easily tends to one side of the track in actual operation, that will cause wheel side wear and rail wear, worsen the vehicle dynamic performance. As a result, the research hotpot of low-floor light rail vehicle naturally turns to the steering capacity of IRW.This article firstly collects and summarizes the studies on steering technologies of low-floor light rail bogies at home and abroad. Then the dynamic performance of four typical low-floor light rail bogies are systematacially analyzed, which are the bogies with small diameter rigid wheels, transverse coupling IRW, longitudinal coupling IRW and normal IRW, mainly from the aspects of steering capacity, stability, ride comfort and safety. The advantages and disadvantages of these bogies are introduced.Because of the complexity of the mechanical coupling structure, the dynamic performance of the IRW bogies are not good. But with the development of the electrical control technologies, the electromechanical coupling technologies with active steering control have been the research focus for the IRW light rail bogies. Electromechanical coupling control technology can get rid of the complex mechanical coupling structure, and not limited by the transmission distance. The article systematically analyzes the steering capacity under different control gains’condition through applying the SIMPACK and SIMULINK united simulation, considering the left and right wheel without rotational speed difference. In addition, for the purpose of solving the problem of the wheel flange contact, the active steering technology with considering a certain rotational speed difference between left and right wheels is investigated. The simulation results show that with left and right wheel rotational speed difference under certain control gains, the active steering can lead the IRW taking the position along the center line of the track, which effectively solves the wheel flange wear problem.