Approximation of ideal characteristic of railway vehicle suspension

Abstract

Proper functioning of the suspension of the railway vehicles is of great importance for the normal functioning of railway traffic. The coil springs are a very common element of the railway vehicles suspension. They are obtained by winding cold drawn wire along the line of the coil with equal distances between the threads. Thanks to these distances, the height of the spring changes easily under the load. Cold drawing is the process of kneading the surface layer of the wire by passing it through a calibrated hole in the cold state. This significantly improves the structure of both the surface layer and the core of wire. All coil springs are made of steel wires, usually round in diameter, and other cross-sectional shapes are possible (square, etc.). The stiffness characteristic of these elements is linear. This paper shows that the ideal characteristic of suspension stiffness of railway vehicles should be exponential. Due to the expensive production of suspension elements that would have an exponential stiffness characteristic, the standard suspension elements which in a certain combination approximates the ideal stiffness characteristic, are used. The whole procedure must satisfy the theoretical postulates presented in this paper. The quality of suspension has a key influence on the quiet running and running safety of railway vehicles.