In this article the results of analytical and experimental research of the strained-and-stressed state of supporting structure of the track machine KRS-1 are presented. The analytical research is executed with the use of finiteelement method (FEM). The results of analytical research are used during realization of running dynamic durability tests. The results of experimental and analytical research are compared. On the basis of analysis of the obtained calculation and experimental data the estimation of durability of supporting structure of the track machine KRS-1 is performed.

Purpose. The purpose of article is to develop the measures of hardness indices improvement of the supporting structures of motor cars of the electric trains ED9M. Methodology. In order to achieve the above stated aims the following measures had to be done: to develop a finite element model of the supporting structures of the motor bogie of the electric train ED9M, determine parameters of the developed model; perform the calculations to determine the stress-strain state during loads corresponding to different operating conditions with the search of geometric parameters reducing the highest stress levels. Findings. The obtained results of calculations (fields of stress distribution and strains in the elements of the motor bogie frame) from the viewpoint of the strength and stiffness discovered the best geometric parameters of the bearings in the central suspension beams of the electric trains ED9M in the places of load transmission from the car body to the bogie frame. Originality. Based on the developed finite element models and the theoretical and experimental researches the scientifically grounded modernization measures of the construction elements of the central suspension beams for motor bogies of the electric trains ED9M were developed. Practical value. It was developed an engineering solution concerning the measures to improve the strength and stiffness characteristics of the central suspension beams for the motor cars of the electric trains ED9M. It was given to the Ukrzaliznytsya's professionals to implement them during repairs.

Purpose. The article objectives are to identify the factors, which can contribute to the formation of cracks and to develop the measures on improving the strength indices of bogie frame transoms of trailing cars. Methodology. In order to achieve these objectives, in performing the work it was conducted the inspection of the technical condition of supporting structures for bogie frames of trailing cars; measured the Brіnell hardness numbers and estimated the endurance limits of transom material; tested on determination of the levels of efforts and stresses being created in the specified transoms under operation; developed the computational models for the theoretical determination of stress levels in the transom by simulating both normal and abnormal conditions of operating loading. Findings. Based on the analysis of results obtained: the situations with the highest stress levels were found; the measures on improving the strength indices of bogie frame transoms of trailing cars were developed. Originality. Based on the experimental and theoretical studies, the scientific monitoring of works to develop the measures on improving the strength indices of bogie frame transoms of trailing cars was carried out. Practical value. The developed measures on improving the strength indices were passed to professionals of Ukrzaliznytsia to introduce the proposed activities during the repairs of electric trains of specified series.