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.