Longitudinal forces in railway track and tamping machine shifting sets

Abstract Following American and British experience some attempts have recently been made in Poland to determine the axial forces in a rail by using the constrained transverse displacement technique. The method is based on vertical dislocation of a rail section separated from the rail-track up to a certain height with the registration of force used for this purpose. An original testing apparatus has been made to measure the forces and displacements. Taking advantage of experimental investigations it was possible to point out that horizontal displacements of the rail are indispensable. Hence, further investigation tasks were concentrated on constrained horizontal dislocations of the entire track grate. Using a specially prepared apparatus it was possible to measure the axial forces within the tamping machine shifting set and the transverse track displacements with various tensile forces in the rails (in the range of 0–500 kN). It was indicated that the tamper is a machine that can be employed for the determination of axial forces in rails using the constrained transverse dislocation technique. The method provides a capability of precise control of the displacement values. It is also possible to utilize measuring force and displacement testers and to create an operator's station. However, the problem is complex, which is indicated by the pulse mode of the horizontal force characterized by a much variable time characteristic.