Development of an ER bypass damper for railway car relief couplers

This paper is a study on the development of an active damper for the couplers of railway cars using electrorheological (ER) fluid as a functional material with the purpose of lowering the coupler force between a relief and a failed train set, which is a very important design factor for the structure of the super express bullet train. A prototype damper is fabricated, which consists of a hydraulic cylinder, an ER bypass slit valve and a PID controller. The buffering force is developed in the ER fluid both through the bypass slit and at the piston-cylinder gap and controlled by adjusting the applied electric field to the ER fluid. Function of the damper is tested through experiments on control the buffering force under various running conditions.