Investigations of methods to measure longitudinal forces in continuous welded rail tracks using the tamping machine

Abstract

This paper briefly presents a survey of the attempts made to find an effective method for the determination of longitudinal forces in continuous welded rails (CWR). Particular attention has been paid to the enforced lateral displacement technique. The primary assertion, which was to prove the necessity of abandoning the lifting of a rail section disconnected from the sleepers, and to concentrate efforts on horizontal displacements, has drawn attention to the use of the tamping machine for diagnostic purposes. In the novel approach to the diagnostic tests of the CWR track by the use of the tamping machine, the fundamental statement related to the registration of the curvature with a definite value of the lateral displacement being subjected to verification, can provide a basis for the determination of the longitudinal axial force in the rail. The finally accepted and developed concept of the measuring apparatus was based on the determination of the distance vector between the rail head and the reference point situated on the frame of the tamping machine. For this purpose, six detecting elements were designed and made. To measure the vector modulus, special induction sensors sliding along the top surface of the rail head were prepared. In order to measure the angle created by the vector between the rail head and the reference point located on the tamping machine frame, induction sensors with a cam mechanism close to the axis of rotation of the instrument were made. Provision was also made for a central unit equipped with electronic systems for processing and filtering the signal. For measuring data acquisition, the authors have elaborated their own computer program in Visual C++ language.

Measurement Methods of Internal Stress in Continuous Welded Rail

“…The principle of this measurement is similar like at the VERSE method, including the disadvantages. However, the disturbing signal produced by the operation of tamping machine turned out to be too high and the attempts to get some CWR stress data were unsuccessful [8].…”

Tests on lateral resistance in railway tracks during the operation of a tamping machine

“…Moreover, the lateral resistance state has an influence on the process of generating geometrical imperfections in the rail track. Hence, many countries are engaged in carrying out work intended to find an effective way to diagnose the state of lateral resistances in railway tracks in operation [1,2].…”

“…The inductive sensors used in some earlier experiments [2] were replaced with strain gauges. This was connected with the character of the operation of the machine posing a great hazard of damaging the inductive sensors which were attached together with As a consequence of this, the whole piston rod hid into the rod end cylinder and damaged the sensor attached to the piston rod.…”

“…Also this time the measuring system designed for some earlier tasks related to the tamping machine had to be modified. In the case of lateral resistance testing, it was necessary to change the position of the measuring point which had to be moved as close as possible to the maximum displacement area (this was not needed in the method worked out to determine the longitudinal forces in the rail sections [2]). An additional problem was the interferences in the circuits of the (specially designed) inductive sliding sensor installed near the lifting-slewing unit.…”

Parametric Analysis of New Tamping Device Based on the Mathematic Modeling

“…According to the parameters as in [5][6][7] and the design size, the maximum of the output shock force is 44kN.…”