Conceptual solutions for control systems of differential tensioners for belt conveyors

Differential tensioning devices for belt conveyors in general and intermediate drives of extended conveyors in the form of closed traction loops are a new type of automatic tensioning devices that differ from other known designs by the presence of a stepwise discrete belt tension control system with separation of compensation functions for belt stretching under load and control of its tension during the operation of the conveyor in order to create optimal modes of belt loading. The article analyzes the well-known and practical concepts of belt conveyor control systems in general. The possibility of controlling the traction force realized by the intermediate belt drive by controlling the tension of the traction and load-carrying belts is shown. On the basis of the analysis, conceptual solutions for control systems for differential tensioning devices of belt conveyors are proposed with the possibility of both autonomous use and application in the structure of an integrated conveyor control system. Possible structures of linear parts of differential tensioning devices are presented, as well as options for the implementation of executive parts that directly move tensioning elements.

Preliminary layout of the main technological equipment of a self-propelled machine with a rod mechanism for installing and fixing the end tower for a mobile ropeway

Mobile ropeways for carrying out transport operations, formed with the help of terminal transport units connected by a single cable system on the basis of self-propelled wheeled or tracked chassis of increased carrying capacity and cross-country ability, are a promising type of lifting and transport equipment that ensures the rapid deployment of the necessary technological means. The article discusses the issues of preliminary arrangement of the rod mechanism for installation and fixation in the working position of the end tower using a folding rod consisting of two articulated links for a constructive variant of the outrigger placement of the tower on a rotary platform. The design and principle of operation of the rod mechanism is considered. A mathematical model has been developed that provides the required normative vertical dimension of a self-propelled vehicle for the purpose of its safe independent movement to the deployment site on general-purpose highways. The analysis of the influence of normative dimensional requirements, the structural dimensions of the bearing frame of the chassis and the height of the end tower on the main structural dimensions of the articulated folding rod in the transport position is carried out.

Reducing the hydrodynamic force in the hydraulic distributor by modernizing the spool coupe parts

Due to a sharp change in the direction and velocity of the fluid flow in the hydraulic distributor, hydrodynamic forces arise. When positioning and holding the spool, the magnitude of the above forces determines the required control power. The aim of the article was to find an optimal constructive solution that would reduce the influence of hydrodynamic forces. In the article we have considered the theoretical foundations laid in the analytical solution of the problem of calculating the magnitude of the hydrodynamic force acting on the plunger of the spool. In addition, a numerical experiment was carried out using CAD Solidworks and the Flow Simulation application package and a comparison of the results obtained with the analytical solution of the problem. During the numerical experiment, it was found that by upgrading the spool sleeve, it is possible to reduce the value of the hydrodynamic force by 4.5 times, compared with the original design. At the same time, it was found that the modernization of the plunger does not further reduce the maximum hydrodynamic forces. The article highlights the economic benefits of reducing the required power to control the hydraulic distributor. The article may be of interest to both researchers whose research interests lie in the field of hydrodynamics, and manufacturers of hydraulics.

Assessment of the strength of the cabin mounting elements of the high-capacity wheeled chassis

The article deals with the issues of modeling the stress-strain state of the attachment points of the cab of a wheeled chassis of high load capacity. The main design loads are determined. Geometric and computational finite element models are constructed, taking into account the features of the metal structure. The technique of gluing elements of the grid model is applied. The contact interaction of the parts is taken into account. Based on the calculations performed, conclusions are drawn about the compliance of the developed structure with the strength requirements.

Simulation of unloading processes of short dump belt conveyors with speed control belt movement

Short dump belt conveyors are used to create bulk cargo both as an integral part of technological machines in the processing of building materials, and as vehicles in a chain of conveyors for transporting bulk cargo in accordance with the logistics of open warehouses. When implementing mechanization schemes for open warehouses, depending on the degree of variability of the cargo flow in the structures of such conveyors, drives can be used that allow regulating the speed of the belts, thereby controlling the productivity of the entire line. Often, short belt conveyors are not equipped with specialized unloading devices, which requires elaboration of the issues of movement of cargo particles during unloading, especially if the conveyor is operating in a production line. The article simulates the processes of unloading short dump belt conveyors when controlling the speed of the belt. Trajectories of movement of cargo particles for various parameters of conveyors are obtained: belt speed, conveyor tilt angle to the horizon, diameter of the unloading drum. It is shown that it is necessary to simulate unloading processes in all cases with belt speed control and conveyor operation without specialized unloading devices.

Physical-mathematical model of ground adhesion on the surface of the excavating parts of earthmoving machines

A large number of domestic and foreign scientists were engaged in the wear of the surfaces of the excavating parts of earthmoving machines during their interaction with the ground, as well as the problem of the adhesion of soils on the surface of the working excavating parts of machines and methods of struggle. It is known that the classical theory of digging is based on empirical dependencies obtained experimentally. They allow, basically, to reveal the essence of the process of dredging, but they differ from each other, both in their description and in the number of results. In this article, the authors propose, on the basis of probability theory, theoretical studies of the process of dredging and the interaction of the excavating part with the soil. The authors of previous studies confirm the obtained results. The developed physical model of the interaction of soil particles with the surface of the excavating part during adhesion allows us to reveal the physical cause of the process of wear of the surface of the excavating parts.

Modeling of the load of a water-reflecting shield of a floating mobile machine

Floating mobile machines have become widespread as a base for the creation of transport and technological complexes. They can also be used as the chassis of base stations of mobile transport and reloading rope complexes. One of the most important components ensuring safe navigation is a wave-reflecting shield that increases buoyancy and prevents the car from being flooded by an oncoming wave. The article discusses the methodology of modeling and the results of calculating the water-reflecting shield of a floating mobile machine manufactured by JSC «BAZ».

Assessment of the resource formation of truck tires in mountainous conditions during the construction of the Rogun hydro power plants

In the harsh mountainous conditions of the operation of trucks during the construction of hydraulic structures, the car tire is the most vulnerable element that determines the efficiency of the transport process and the cost of transportation. Due to a significant decrease in the resource of truck tires in the harsh mountain conditions, the cost of operating a vehicle increases significantly. The purpose of the study is related to the assessment, adjustment and regulation of the resource, as well as planning the costs of purchasing and the entire life cycle of truck tires operated in mountainous conditions. The work is devoted to the assessment of the formation of the resource of truck tires in the mountainous conditions of the construction of the Rogun HPP, taking into account the influence of the most significant factors. To assess the formation of the resource of truck tires in the mountainous conditions of the construction of the Rogun HPP, an integrated scientific approach was used, taking into account the most significant factors. The assessment of the influence of fluctuations of external influences on the object of research, depending on the conditions and nature of the process of formation of the tire resource was carried out by the probabilistic-statistical method, and the empirical characteristics of the distribution of the above factors were calculated by the method of V.I. Romanovsky. The simplified mathematical model presented in the article can be recommended when adjusting the tire resources of trucks in mountainous conditions during the construction of hydraulic structures (for example, the construction of the Rogun HPP). The practical significance of the work is associated with the selection and planning of the need for automobile tires, operated in mountain conditions. The research results can be recommended for assessing the resource of tires of various standard sizes and designs mounted on trucks of various modifications, operated in various road and climatic conditions during the construction of hydraulic structures.

Structural analysis of freight car lever transmission with parallel shoe releasing devices taking into account the edge contact of the shoe and wheel

The article deals with the issues of modeling the stress-strain state of the attachment points of the cab of a wheeled chassis of high load capacity. The main design loads are determined. Geometric and computational finite element models are constructed, taking into account the features of the metal structure. The technique of gluing elements of the grid model is applied. The contact interaction of the parts is taken into account. Based on the calculations performed, conclusions are drawn about the compliance of the developed structure with the strength requirements.

Assessment of the influence of the normalized vegetation index on the fire situation in the fire-hazardous period

The paper presents an analysis of the parameter obtained by remote sensing of the planet Earth, the normalized vegetation index (NDVI index). The results of assessing the impact of the index on the occurrence of fires in a certain area are presented. Using the example of statistical data for the Krasnoyarsk Territory, the index values for two periods of spring and summer were obtained, and the influence of NDVI values on the change in the probability of a forest fire was estimated. Static data on the index were selected from the «data lake» of the Ministry of Emergency Situations of Russia, data is collected from 2014 to the present, and data on thermal points from 2012. The consequences after wildfires will cause significant damage to forestry in Russia, and to the environment as a whole. Therefore, the allocation of previously known areas with a high probability of a natural fire will not only improve preventive measures for prevention, but will also make it possible to prevent most of the consequences. This article considers one of the parameters obtained by remote sensing of the Earth NDVI of its change before and after the event in question (natural fire).