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The causes of deformation in the zone of welded joints are considered. Authors experimentally studied changes in hardness on the rolling surface of the rail in the longitudinal and transverse profiles within the thermally affected zone of the welded joint. It is established that the hardness of the rolling surface of the rail in the longitudinal direction in the thermally affected zone of the joint is uneven and is determined by the structures arising from the effects of the thermal cycles of welding and the quality of the local heat treatment. In this case, two "low spots" are clearly traced with a decrease in hardness to 290...300 HB and with a higher hardness up to 350 HB right in the welded joint. Experimentally investigated the change in the depth of the welded joint from the implemented tonnage. At the same time with strain gauge method, using the force method developed by N. N. Kudryavtsev, continuous changes in vertical forces when the wheels move along the welded joint zone were recorded. Average values of vertical forces from loaded cars were established. Experimental distributions of vertical forces were approximated by theoretical laws according to the Kolmogorov — Smirnov matching criterion. Recommendations are given on minimizing the harmful impact of rolling stock on the track in areas of lowering welded joints.The following conclusions were made.1. Geometry of the joint irregularity is in the form of a W-shaped deformation with an influx of metal on the receiving rail and lowering on the directing rail. The width of the upper part of the deformation varies between 160...200 mm along the axis of the rail.2. Deformation zone of the welded joint is a source of increased dynamic impact from the wheels of the rolling stock on the elements of the upper track structure. According to the results of experimental studies it was found that the greatest increase in dynamic effects was observed from locomotive wheels up to 45.. . 70 kN, maximum values reached 180...210 kN, from the wheels of loaded freight cars the values of vertical forces increased by 35.. .45 kN, maximum values reached 145...170 kN, from the wheels of empty cars increase dynamic impacts amounted to 14...16 kN, maximum values reached 32...36 kN.

Analysis of operational data for defective and highly defective rails showed that up to 25 % is the contact-fatigue defects. In connection with the development of heavy haul traffic on the Russian railways, it is relevant to determine the influence of cars with increased axial loads of 25 and 27 tf on the contact fatigue life of rails. The solution of this problem is set forth in this article. The Brown-Miller model of multi-axial fatigue was used in the calculation. This model is integrated into the Fatigue software system, which is tied to the Marc calculation system through Pat-ran. Since under operating conditions the wheel moves (rolls) along the rail on meandering trajectory, in computer modeling weight coefficients were taken into account that characterize the percentage of wheels in the cross-sectional areas of the rail. Calculations of contact fatigue life took into account the variability of vertical loads from the impact on the track of trains formed from innovative open cars with axial loads of 23.5, 25 and 27 tf under operating conditions, loaded with real loading blocks. According to the analysis of calculated data with an increase in axial loads from 23.5 to 25 tf, it is necessary to expect a decrease in the service life of rails in contact fatigue resistance by 19 %, with a further increase in axle loads of up to 27 tf per 32 %. Considering that the share of freight cars with axial loads of 25 tf does not exceed 15...20 %, then on the routes of its use the service life of rails should be expected to decrease by 3...4 %. The method proposed by the authors for predicting the contact fatigue life of rails with increasing axial loads is advisable to improve in part of the experimental determination of the fatigue and strength characteristics of rail steel from the degree of hardening of the rolling surface, its probabilistic properties and the use of the integral distribution law for vertical forces, taking into account the structure of the freight traffic passing through the section. The work was carried out according to the RFBR project 17-20 01088.

From the practice of engineering design it is known that in the development of mechanical systems, the operation of which is certainly not based on the phenomena of resonance, self-synchronization, etc., one should be wary of the proximity of the frequencies of free oscillations in such mechanical systems in different forms. Transient processes are dangerous due to the excitation of significant quantities of mechanical stresses and their damage to structures before destruction. This effect can also be appeared in wheel pairs (WS) of locomotives during operation. On the finite element model (FE) of the electric locomotive wheelset, calculations of natural frequencies and vibration modes are performed, the case of torsional oscillation frequencies with the participation of the electric drive gear and bending (saddle-shaped) oscillations of the running wheels is demonstrated, which can accelerate the processes of origin and development in its fatigue cracks. Paper discusses methodical issues of performing such calculations, problems of assessing the degree of danger of proximity of vibration frequencies of structural elements. The prototype of the finite-element model considered in the article was the WS of a locomotive with an asynchronous transmission, a one-way reducer and a composite retaining wheel. Methodical issues of performing such calculations, problems of assessing the degree of danger of proximity of vibration frequencies of structural elements are discussed. The results of calculations in combination with their visualization give a fairly complete idea of the behavior of the wheelset in the traction drive, while allowing studying the stress-strain state of its parts, and also providing an opportunity to identify the damaged elements and zones. It is highly advisable to carry out similar studies on virtual models when analyzing the operation of locomotive structures and assemblies under extreme operating conditions (for example, in case of boxing), which is not practicable or dangerous by experimental methods. It is possible, as shown, and it is necessary at the design stage of the WS to conduct its frequency analysis in the manner described in the article and, based on its results, perform a resonant detuning in a constructive or software way in the frequency range of the modulation of the operation of an asynchronous drive. To this end, by analogy with the AAR S-669 standard (USA), it is necessary to develop a domestic regulatory document for the projected locomotives with an asynchronous drive.

Interaction of rolling stock and track is a fundamental physical process while running cars, locomotives and trains on the railway. The Research, Design and Technological Institute of the rolling stock (JSC "VNIKTI") for more than twenty years conducting research to reduce cost of energy for traction.The Institute has developed rail lubrication technology performed by locomotive leading the train, but with the improvement: the lubrication of the internal rolling surface of the rail in curve performed by leading locomotive and on sections where lubrication made on side surface of the head of the outer rail - by lubricating cars. This technology can reduce the side impact of the rolling stock on the railway track in curved sections, to reduce resistance to motion while maintaining the length of the braking distance. The effect of reducing the side impact to the track is achieved by reducing the coefficient of friction on the rolling surface of the inner rail and the side surface of the outer rail, which leads to a proportional reduction of transverse forces of creep. Such reduction of transverse forces in creep decreases the normal reaction at the flange of the oncoming wheel and, consequently, reduces motion resistance (reduction in energy consumption for traction), reduce wear, both wheel flanges of rolling stock and rails in curves.Lubrication of rail by traction unit in the train has a broad perspective of application on the railway network of JSC "Russian Railways". The minimum cost of additional equipping locomotives with devices automatically applying friction modifiers and manufacture of friction modifiers will payback considerable profit by savings of traction resources and by savings associated with a reduction in regrinding of wheelsets and replacement of rails in curves.

The article presents results of pilot and theoretical studies of JSC VNIKTI in the field of interaction of railway track and a rolling stock and perspective of their application. Questions of longitudinal dynamics in the conditions of different types of braking of trains of increased weight and lengths and their influence on infrastructure are considered. Analysis of dynamic qualities and indicators of impact of model of coupled trainset on track is carried out by means of computer modeling, and impact evaluation of action of longitudinal force on carriage indicators, both dynamic and by impact on track, is given at different conditions of railway track. As a result of testing in 2015 of doubled trains weighing up to 14,200 tonnes at various types of braking the following conclusions were obtained: 1. The considerable array of experimental data on interaction of a rolling stock and way at emergency braking is received allowing a quantitative assessment to this process. 2. When performing asynchronous emergency brakings the “practical top” of the compressive forces in the train (1600 kN) has been for the first time reached and the moment of loss of stability of a rolling stock in a rail gauge has been recorded. 3. When performing synchronous braking sufficient stability of the conducted locomotive and nearby the standing car is confirmed at influence of longitudinal forces. 4. The received results of pilot and theoretical studies can be used for modification of normative documentation for development of local instructions for safe driving of the coupled trains, and furthermore at the organization of pilot trips of the coupled trains of higher weight.

Purpose. Study the possibility of using geometrically-force method to determine sections of high risk of derailment in railway stations at empty wagons movement. In the test program track diagnosing subject to longitudinal forces in the freight train effecting empty wagons is provided. Methodology. To this effect empty mineral wagon and thermal cistern were equipped with strain-gauge wheel sets, strain-gauge automatic coupler and other instruments, set in the freight train weighing 4500 t. Findings. In the course of this work it was ascertained that the geometric-force ethod gives possibility to receive additional information about the track condition from the position of empty cars stability against derailment. It is shown that some sections of high risk of derailment pieces of line does not discarded by traditional ways, based on an assessment of the geometric parameters of the way. Those track sections are identified by this method, which can not be evaluated by technical means, used currently on track measurement cars. Pieces of line with low parameters on empty cars stability against derailment are individual and they are determined not only by the sizes of deviations, but their form, a combination of different types of roughness, profile and defective elements of the permanent way. Originality. Geometric-force method should be considered as complementary to the existing technology assessment of the way on the geometrical parameters; its implementation will allow revealing the track section, dangerous for the motion of empty wagons. Practical value. For the geometrically-force method realization of assessment of the way in the railway network of JSC «Russian Railways» it is proposed on the basis of the accumulated statistics and experimental data in accordance with wagons tests with a high center of gravity to develop specialized software for wagons through gauges to assess ways bygeometrically-force method that excludes the use in technology assessment of the additional freight wagon way with a strain-gauge wheel sets.