When a vehicle runs in the section where the influence of the twisted track is dominant, such as a transition curve of the end section of a curve, the outer rail side wheel load of the front axle may decrease by the surface twist which is generated between the bogie and the track. In such cases, if large lateral force occurs, the bogie will be uplifted on the rail by the wheel, increasing in the danger of derailment. In order to prevent such flange climb derailment, the reduction of lateral force and the control of wheel load decrement is effective. We developed a new type of bogie for conventional lines from a viewpoint of preventing flange climb derailment by the control of wheel load decrement. The bogie is equipped with a bogie frame composed of three blocks which are joined together via a rotation mechanism. The bogie can follow the twist of a track by rotating the side beams with the rotation mechanism and the control of wheel load decrement, which brings about improved safety from flange climb derailment. We confirmed satisfactory performance of the bogie by conducting some experiments.
