A 9-kN magneto-rheological (MR) damper for lateral suspension control of a railway vehicle is created in this paper. The twin-tube style is adopted in order to obtain a long damper stroke and guarantee the symmetry of the output damping force. A bypass MR valve with a radial flow path is utilised to control the generated damping force. Three-dimensional finite element analysis studies are performed to determine the magnetic field strength inside the MR valve region. The MR damper is mathematically modelled for the situation of a unidirectional fluid flow in the chamber and valve. The test results indicate that the MR damper can produce a considerable range of dynamic force and can operate as a fail-safe device. Sedimentation is detected in the damper; however, the response time is acceptable for real-world deployment.