The paper presents the findings of the investigative study on the features of electric drives in the continuous run modes (which correspond to the run modes of belt conveyor drives) using frequency converters and operating with the natural mechanical characteristics. The description of the test bench in the form of the generalized mechanism of the hoisting machine is provided. The paper formulates features and limitations of the heat control procedure taking into account environmental conditions and surface conditions of the research object. The sequence of the experiment is provided. The thermograms of the thermal photography are obtained and interpreted. The data is presented as temperature curves of the research object. The analysis of the data made it possible to confirm correctness of the recommendations proposed earlier on taking into account the type of the drive controlling system when building probabilistic mathematical models of the tractive force distribution, particularly when solving the task of computational distribution conservation of the tractive efforts between the drives.

The paper is aimed at specifying and summarizing system-wide and internal slide variations of electric motors in the structures of multimotor drives of multidrive belt conveyors. The accounting principle of the indicated variations is formulated in the form of the hierarchic structure when building a probabilistic mathematical model of tractive effort distribution in the multidrive belt conveyor. A system of the obligatory internal combinations of slide variations of electric motors in the multidrive belt conveyor is suggested. Taking into account the recommendations of the given system, the dependencies enabling one to estimate the labour coefficient of the probabilistic modelling and give detailed and qualitative descriptions of every design case are suggested.

Asphalt concrete, being a durable composite material, has found wide application in construction. Especially it is necessary to highlight its use as a road surface as a common and popular material. The process of compacting asphalt concrete by road rollers is a complex process, with its own specifics and disadvantages. The purpose of the research is to substantiate the availability of technologies for the continuous compaction of asphalt concrete pavement with a road roller. This article analyzes the drawbacks of current technology (reciprocating compaction with braking) and discusses possible solutions to problems by progressively compressing the mixture. The scheme of interaction between the roller of the roller with the compacted asphalt-concrete mixture is presented, the negative consequences of the reciprocating motion of the roller and sudden braking on the laid floor are described. The interrelationship of defects and their causes due to the fault of the roller or its driver were examined and analyzed. The expected effect from the introduction of the translational seal instead of the cyclic one is presented. In conclusion, the non-stop compaction of asphalt concrete pavement with a road roller is justified, and the advantages and disadvantages of various rolling technologies are described.

The article presents materials on the study of mathematical modeling of jointing (splicing) of a steel rope used to transfer the traction force by friction forces. The developed mathematical model of jointing describes the stress-strain state of strands (wires) from quasi-static loads arising in the process of cyclic stretching and bending of the steel rope on the traction pulley, in which the resultant force in the pop-river section of the steel rope shifts relative to the central axis, causing its bending and twisting. Using experimental data, it is established that the torsion and bending of the steel rope is called the technology of jointing in the nodes where the replacement of strands occurs. It is experimentally established that defects in the area of jointing (splicing) are manifested as a result of cyclic tensile and bending loads on the pulley, which is associated with limited mobility of the strands in the nodes due to a violation of the symmetry of the cross section. When stretching and bending on the pulley, the load between the strands of the rope is distributed very unequally, which ultimately leads to its out-of-center stretching and the formation of a «wavy» defect. The mathematical model describes the process of jointing (splicing) of the steel plate, taking into account the existing technology that violates the symmetry of the cross section in the nodes, which, as a result of quasi-static loads, develops to critical values of the rejection index «waviness».

In the article researches of increase of strength of motionless connections of wheeled and caterpillar cars due to use of cylindrical landings with a contour connection of details are resulted. The technique of designing and technological support of the connections possessing a number of operational advantages is developed. It has been shown by calculation and experimentation on a concrete example that a loop connection can significantly increase the strength compared to standard types with an interference fit.

The article is devoted to the problem of increasing the efficiency of the use of frequency adjustment of the hydraulic drive of the mechanisms for the movement of links of articulated manipulation systems of mobile transport-technological machines. Earlier, the authors showed that the type of law regulating the rotational speed of a volumetric pump shaft and its quantitative characteristics have a decisive influence on the type and quantitative characteristics of graphs of the time variation of the kinematic and hydraulic parameters of the links movement. A quantitative analysis of various laws of regulation is made on the example of the rotary movement of the link of a full-scale manipulation system. It is shown that the most favorable form of the law for changing the shaft rotation speed of the variable displacement pump is S-shaped. Criteria of quality of regulation are formulated, which make it possible to ensure favorable parameters of movement (absence of dynamic movement instability) taking into account the magnitude of the operating operational loads and structural dimensions of the links. Mathematical model is proposed, allowing to synthesize the laws of frequency adjustment, which are optimal for individual quality criteria – the minimum time to work out the movement (single-criterion optimization). A description of a computer program that implements the proposed mathematical models is given.

The article discusses the methods of constructing mathematical models describing the heat balance in the “hydraulic puller-drill shaft” node used in jet-grouting machines during high pressure transmission from stationary elements to rotating parts of the mechanism. The main heat fluxes, which include the heat flux in the hydraulic removal system; heat flow to the water-cement mixture, heat flow to the pre-compression mechanism, heat flow to the drill shaftand methods for solving the heat conduction equation for calculating the temperature field distribution that are formed during the operation of this structural unit are shown.Thus, the proposed modeling technique will allow us to consider and calculate the heat balance of the designed structural jet-grouting unit of ultrahigh pressure, as a set of heat fluxes generated during the operation of this device, considering it as heat sources, from which heat transfer occurs during the operation of the «hydraulic puller», a sealing element, which will ensure predictability of design characteristics of the device design and increase their efficiency. This approach makes it possible to more fully consider the existing main heat fluxes and more accurately simulate the heat balance as part of the assessment of the stress-strain state of ultra-high pressure jet-grouting devices.

The article discusses the issues of increasing the durability of road-building machines. As a subject of research, friction units are considered, the details of which are made of gray iron. On the basis of a comprehensive technical and economic analysis of hardening methods for cast iron parts, it was established that chemical-heat treatment has the best combination of criteria. The methods used in practice for hardening cast irons are of little use in the conditions of repair production due to the complexity of technological processes and equipment. In addition, the thickness of the hardened layer usually does not exceed 0.3 mm. The paper discusses the main aspects of the application of new technology of surface hardening, formulated recommendations for its use, depending on the service purpose details. An assessment of the technical level of the proposed solutions compared with traditional technologies of hardening of cast iron.

The article presents the research data on the influence of the gear pair materials hardness of the cylindrical transmission on the overall and connecting dimensions and center distance of the single-stage gearbox, made according to the horizontal scheme, with the help of the created automated software complex, which allows to link the design and verification calculations of the gearbox parts with its parametric 3D model. The software package allows to carry out a number of optimization and research tasks in a short time, excluding calculation errors and data transfer to the 3D model when rebuilding its geometry for a variety of sizes of gearboxes, as well as to predict and visualize the size of the product as a whole and all its parts individually almost immediately after receiving the technical requirement. The researches were carried out in the range of torques on the output shaft from 250 to 500 Nm; gear ratios from 4 to 8; the speed of the input shaft 1500 min-1, the resource of the gearbox 12500 hours. The hardness of the material of the gear pair varied from 160 to 300 ??. The analysis of the obtained results is conducted with the study of changes in the size of the children parts included in the reducer. The conclusion about the value of the change in the center distance and overall dimensions according to the hardness of the gear pair change by 140 ?? was made.

In the process of performing a technological operation on the working body of the road mill sharply variable random loads occur. This is due to the periodic nature of the interaction of the cutting elements with the material being processed and the random nature of the change in the milling depth, the physical and mechanical properties of the medium being processed, as well as the operating modes. The article proposes a model of formation of the moment of resistance on the mill during interaction with the processed material. The case when the working body consists of several sections, each of which has several cutting planes, with a different number of knives in the plane, is considered. Factors that determine the nature of the load, such as the frequency of interaction of the cutting elements with the processed material and the randomness of the operating conditions of the unit, lead to their presentation as a sequence of pulses with random parameters. Expressions are obtained in the article that allow calculating the mathematical expectation and spectral density of the moment on the working body at the design stage, taking into account the operating modes, its design, the physico-mechanical properties of the milled material and their probabilistic characteristics. The probabilistic characteristics of the loads on the mill serve as initial information for the dynamic analysis of the drive system and the design of the unit, its strength analysis, and the selection of optimal parameters and operating modes.

Load gripping devices are used in any lifting operation and are used to attach the load to the construction machine, in most cases, to the crane hook. The most important quality of the product — safety-depends on the correct choice of the device, its technical characteristics, reliability parameters, as well as competent operation and application. The article presents an analysis of methods and approaches to assessing the risk of using load gripping devices when performing lifting operations. The problem of designing a clamping action grip for lifting the load with the possibility of turning from a horizontal position to a vertical one is described. The hazardous situation and the likelihood of operator error in the slinging of cargo. The practical example of reduction of risk of operation of the load gripping device for the purpose of increase of safety at its use is considered. The necessity of application of the term «safety culture» for all stages of life cycle of load gripping devices is explained and the necessity of preliminary preparation of design and operational documentation in interrelation with technological features or possibilities of concrete production is pointed out. The result has been achieved by the introduction into operation of the design of the clamping action for lifting the wheel in conjunction with the safe working methods reflected in the product data sheet and in the operating manual. The conclusions emphasize the need to expand the experience gained to other types and types of seizures, the need to systematize and summarize the experience gained, as well as the accumulation of statistical data.