In the paper on the basis of the Rostechnadzor report data there is revealed the topicality of the work connected with stability loss of boom self-propelled cranes during the work on weak load-bearing soils. The fulfilled out theoretical investigations of effort distribution in supports depending upon the angle of a boom pitch (boom extension), the angle of boom rotation in a horizontal plane and the weight of the load to be lifted allowed offering a practical realization of measures for boom self-propelled cranes updating at the expense of the introduction of underlying mechanisms allowing not only the assurance of surface horizontal positioning, but the change of soil bearing capacity (supporting surface). For the determination of the effectiveness of the device offered ensuring a table work on weak load-bearing soils there was developed a procedure for the fulfillment of experimental investigations consisting of two stages. At the first stage there were defined efforts in crane supports depending upon a weight of the load to be lifted and sp-acial boom position. At the second stage there was carried out an estimate of crane support subsidence into soil of different state for basic and updated machines. The investigation results are confirmed with confidence probability of 0.95 by Cochran, Student and Fisher criteria. As a result of experimental investigation carrying out there was defined that the application of an updated design allows increasing self-propelled crane stability by 1.41… 2.27 times.

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The purpose of the paper is to reproduce a standard wind flow (laminar, turbulent, pulsating modes) to study the impact on crane structures, with the aim to obtain the load values of crane elements most closely approximate to real conditions. When creating an installation, which is related to the field of experimental aerodynamics, the "principle of simulating the main factors determined by the operating conditions of the research object" is adopted to ensure the r eproducibility of test results to the maximum extent. To confirm the performance efficiency of the proposed installation device, its computer model is developed using the CAD software SolidWorks. The computer model parameters are in full geometric agreement with the dimensions of the developed real installation. The use of the installation makes it possible to study the dynamic effect of the wind on the stability of crane structures in various operation modes (change in wind speed, in the mode of load operation, in operation conditions at the wall, etc.). The proposed installation allows to simulate the loads on crane equipment with the possibility of characteristics expanding, for example, its carrying capacity. The generated computer model of the installation makes it possible to reveal the physical picture of wind flow distribution at the installation outlet. The results of wind flow simulation on the proposed installation are confirmed on a computer model with a high degree of convergence of results at wind speeds of 2.5 m/s and lower The installation proposed by the authors will allow to simulate: the value of the real average statistical wind load of various intensity; pulsating component of the wind load; vortex excitation; increase of the available aerodynamic research capability for a real crane structure. The developed installation is a calibration device for external impacts of the wind force on the crane structure.

The analysis of the accident rate of crane structures indicates that the most common cause of accidents with tower cranes is the wind load. The wind load is considered under working and non-working condition. In the working state, the maximum wind load is considered, at which the operation of the crane with the rated load is ensured. In the non-working state, the calculation is carried out using the coefficient accounting for the change in dynamic pressure depending on the height of the location from the ground surface of the given structural element in the non-working and working states of the crane. However, the regulatory documents as a rule do not consider the random nature of the wind load, although the research materials on changes in wind speed (gusts), proposed in the scientific and technical literature, indicate the interval character of their action. The objective of the research was to study the nature of loading of the tower crane structures, which makes it possible to assess the change in the oscillatory process in the element of the crane metal structure exposed to the action of the wind load. The design scheme proposed in the article considers the change in intensity of the wind load along the height of the crane and the random nature of its change, which together lead to the occurrence of longitudinal, torsional, and bending vibrations. Oscillations of the crane metal structure were considered by the authors as oscillations of an oscillator with given parameters of the oscillation amplitude, system masses (boom and tower), and the weight of the load being lifted. The mechanical state of the system (rigidity and elasticity) was considered as well. Theoretical studies of the system under consideration were carried out in two versions:1) as of an elastic-viscous medium; 2) as of a continuous system. The results obtained made it possible to reveal the physical nature of the oscillatory process and to carry out quantitative assessment of the change in the loading of the metal structures of the tower crane. The theoretical studies allowed to obtain expression, which makes it possible to evaluate the change in the oscillatory process in the element of the crane metal structure exposed to the action of the wind load, which has a random nature of loading.

Modern railway rolling stock should meet requirements regarding comfort (maximum travel speed with minimum vibrations of wagons, noiselessness of movement, etc.).To eliminate the influence of dynamic loads, rolling stock is equipped with vibration dampers. The objective of the work is to select the parameters of the vibration dampers of rolling stock, depending on its characteristics, to ensure the due indicators of comfort and safety of transportation of passengers and goods by rail. To achieve this objective, applied methods of mathematical modelling were based on numerical programming of operation of dynamic systems. The indicators of vibration dampers are evaluated according to the results of studies of the dynamics of the rolling stock (in particular, of vibration protection rates).Assessment of dynamic state of the rolling stock implies application of methods of mathematical and physical modelling, which include the development of a physical and mathematical model, a calculation algorithm, and computer programming. The study of the mathematical model by numerical methods makes it possible to carry out a multifactorial experiment using a large number of input parameters (factors) and to select the characteristics of vibration dampers that are optimal for the conditions under consideration.To solve dynamic problems, the harmonic perturbation model, which is the most widespread, was specified in the form of a sinusoid with a period corresponding to the rail length.A quantitative assessment of the vibration process (frequency, amplitude) makes it possible to identify the main processes occurring in the system under consideration under various types of external load. The introduced assumptions related to rigidity, mobility and geometric immutability of the system allow determining the methods for obtaining a mathematical model and considering the vibrations as flat ones.The equations were solved in MathCad Prime 4.0 package using the Runge–Kutta method with automatic step selection. The subsequent study of the properties of the dynamic system was carried out by changing the resistance parameter of dampers of the first stage of spring suspension, while recording the values of the amplitude of the vibrations of the system and the period.The analysis of the results has shown that the vibration period of the body and bogies under any changes in the resistance parameter of the damper remains unchanged, while rational parameters of resistance of axle box dampers have been revealed for specified indicators. Hydraulic vibration dampers with the revealed parameters used on rolling stock help to reduce wear and damageability of running gears, improve ride comfort and traffic safety, as well as to reduce repair and maintenance costs.