The Railway Wheelset and Suspension Unit as a Closed-Loop Guidance Control System: A Method for Performance Improvement

Abstract

Using a simplified mathematical model, the conventional railway wheelset and suspension unit is shown to behave as a closed-loop guidance control system. The centre-line of the track corresponds to the input, and the lateral position of the centroid of the wheelset to the output. Analysis of the system shows that, while it may be made stable at up to high speeds, the performance in the stable region is unsatisfactory in certain respects. This is attributed to the large forces of interaction between the wheels and rails at the points of contact, arising, in the case of the conventional wheelset, from creepage. These forces may be reduced and controlled by interposing a coupling having viscous characteristics between the wheels, in place of the rigid axle. The new arrangement is shown to be much more flexible, and capable of fulfilling a wide range of performance requirements.