The method of calculating the strength of the frame of specialized vehicles for the transportation of bulky heavy loads is presented. The methodology describes the process of constructing a design scheme in a general way to determine all the loads that occur on the vehicle frame using a set of axles and inserts (spaces). These functional dependencies allow us to determine the bending moments and shearing forces in the frame depending on: the vehicle's own weight; the amount and load on the supports from the load; the resulting inertial loads when braking the vehicle. Based on the developed methodology, histograms of changes in bending moment and shearing forces are constructed for a specific transport scheme for the transportation of heavy bulky cargo.

Introduction. In the modern world, in order to increase the mobility and traffic safety of vehicles, as well as to increase the service life of brake mechanisms, a wear-resistant brake system is widely used on heavy wheeled vehicles, which makes it possible to provide service deceleration of the vehicle without the use of friction brakes. One of the main units that make up such a deceleration system is a hydrodynamic retarder, the study of the characteristics of which is devoted to this work.

Objective. Providing a given mechanical characteristic of a hydrodynamic retarder by optimizing the blade part.

Methodology and methods. To study the influence of the parameters of the bladed part on the characteristics of the hydrodynamic retarder, CFD methods are used to determine the values of the dynamic/energy characteristics of the flow in the interblade space of the hydraulic brake, considering the influence of the geometric features of the flow path, as well as the physical and mechanical properties of the working fluid. Within the framework of the article, a finitevolume model of the fluid part of the hydraulic brake was created in the Ansys Fluent software package, and the dependence of the characteristics of the hydraulic brake on the internal elements of the blade part was analyzed: the number of blades, the angle of inclination of the blades, the shape of the fluid part.

Results and scientific novelty. The presented approach allows iteratively to carry out the synthesis of hydraulic brake impellers. At the same time, the obtained results of the study on the influence of the angle of inclination, the number and shape of the blades on the torque coefficient of the hydraulic brake make it possible to rationally choose the initial approximation and reduce the number of iterations.

Practical significance. Data on the influence of the parameters of the flow path on the characteristics of the hydraulic brake make it possible at the design stage to evaluate the possibility of creating acceptable designs of hydrodynamic retarders for use on wheeled vehicles.

Introduction. The creation of hydraulic retarders for use in transport equipment (hydrodynamic retarders) is associated with the implementation of the specified mechanical characteristics with the minimum overall dimensions of the product, limited by the cramped layout of the machine. This circumstance requires a wide range of studies on the influence of hydraulic brake parameters, for example, the number and angle of inclination of the blades, the shape of the flow path and the physical and mechanical properties of the working fluid on the implemented mechanical characteristic of the assembly in order to optimize the latter in terms of weight and size parameters.

Objective. Verification of the mathematical model of the dynamics of the working fluid in the fluid part of the hydraulic brake, to confirm the calculated data obtained with its help.

Methodology and methods. Verification of the developed model was carried out by performing a series of experimental studies using a serial hydrodynamic retarder. To ensure the possibility of a correct comparison, the solid model of the impellers of the hydraulic brake, with the help of which the finite volume model of the flow part of the retarder was created, was obtained using a coordinate measuring machine. During the experiment, a number of stationary operating modes were implemented with different rotor speeds and pressure difference between the inlet and outlet lines of the hydraulic brake. Then the obtained modes were reproduced using the developed mathematical model. The comparison was carried out according to the realized braking torque.

Results and scientific novelty. In the course of the studies performed, it was proved that the results obtained using the developed mathematical model of fluid dynamics in the flow part of the hydraulic retarder and in the framework of a full-scale experiment are close. The presented result allows us to consider the developed mathematical model verified and reasonably use it in the study of the influence of various hydraulic brake parameters on its mechanical characteristics.

Practical significance. A mathematical model of fluid dynamics in the flow part of a hydrodynamic retarder has been created and verified. The data obtained make it possible to use it in the design of the blade part of the hydraulic retarder to implement the specified mechanical characteristics of the assembly.

The analysis of the operating algorithm of the existing lifting capacity limiters is given. The considered approach is to disconnect the hoisting mechanism when load limit value is reached. For a number of cranes, characterized by relatively high values of dynamism coefficients, it is shown that it is impossible to meet the safety requirements when using the algorithm with a single threshold.

The purpose of the study was to evaluate the effect of the load limiter, which uses an algorithm of operation with intermediate thresholds of operation, on the safety status of overhead cranes.

The algorithm of the capacity limiter operation with intermediate thresholds is described. The possibility of achieving the requirements of regulatory and technical documentation relating to the protection of the crane from overloading, based on the algorithm of the capacity limiter with intermediate thresholds is confirmed experimentally.

On the experimental basis, the effect of the studied capacity limiter algorithm on the dynamism coefficient is examined. It is shown that while lifting near-nominal loads (85–125% of nominal weight) the peak dynamic load on the crane is reduced by 9.2–29.4%.

It is concluded that the algorithm with intermediate thresholds is applicable to meet the requirements for protecting the crane from overloads. The reduction of dynamic loads during the lifting of near-nominal loads, which increases the lifetime of the crane components, is evaluated.

This article discusses the existing design schemes of suspensions for self-propelled modular vehicles with electronically controlled axles of Cometto company, as well as their characteristics, to assess the effectiveness and feasibility of using each of the presented models of the MSPE series, their advantages and disadvantages are analyzed, which will allow in the future use this information when choosing the required design during operation or when creating domestic analogues.

The introduction describes the applications of self-propelled modular vehicles and their functions. The main part presents the characteristics of the modular transporters of Cometto model range of MSPE series: "MSPE 40T"; "MSPE 48T"; "MSPE EVO2 60T" and "MSPE EVO3 70T". A comparative analysis of the suspensions of two groups of models "MSPE 40T/48T" and "MSPE EVO2 60T / EVO3 70T" was carried out, the advantages and disadvantages of the suspension design of these models are presented.