Methodology for choosing a propulsion device for special-purpose vehicles

The ability to move on different types of soils is one of the main indicators of the efficiency of mobile vehicles in off-road conditions. The movement of such special mobile machines is carried out due to the interaction of the propulsion with the support surface. Therefore, significant reserves to increase productivity and reduce the cost of technological and transport works are laid in reducing energy consumption when the engine interacts with the surface. On the process of interaction of the wheel drive with the deformable support surface it is established that the parameters of this interaction depend on a number of factors: normal load, angular velocity and torque. In the General case, the parameters of interaction of each engine change when changing the mode of movement of the wheeled vehicle, and the ability to change the air pressure in the tires when driving on different support surfaces allows to increase the performance of the wheeled vehicle In the study of the caterpillar, it was found that the pitch of the caterpillar, the stiffness of the caterpillar, the angular stiffness of two adjacent tracks, reducing the pitch of the caterpillar chain, reducing the stiffness of the caterpillar, increasing the angular stiffness of two adjacent tracks, affect the efficiency of the machine. The scientific novelty of the study is to develop a method of choosing the engine of a special mobile machine that works off-road, in the process of its design. Wheel or crawler solutions will mainly determine the performance and efficiency of special purpose vehicles. The choice of engine for special mobile machines is based on a set of criteria. The criteria determine the importance of the implementation of the tasks in relation to the efficiency of functioning. Knowing the sowing capacity of the soil, and taking into account the possibility of movement of a particular special mobile machine depending on the type of soil, you can choose one or another type of engine.

OPTIMIZATION OF PARAMETERS OF THE MOBILE MACHINE ADAPTIVE HYDRAULIC CIRCUIT

Mobile machine hydraulic circuits tend to adopt electrohydraulics. Such hydraulic circuits are based on controlled pumps, modulated hydraulics, sensors and controllers. This allows adapting the hydraulic circuit operating modes to the changes of external conditions of the machine operation. Application of hydraulic circuits with electrohydraulics in mobile machines allows to use mobile machines efficiently with a high number of removable endangers, increases their performance and improves the quality of performed works. The authors propose an adaptive hydraulic circuit for a mobile machine. The operation process in the adaptive hydraulic circuit in static and dynamic modes is determined by the interaction of the pump controller and pressure differential control valves. The hydraulic system operation stability, its fast response and readjustment are determined by the controller parameters. It has been revealed that the main parameters affecting the dynamic characteristics of the hydraulic system are: throttle area and coefficient of amplifying the pump controller orifice, dampener area and coefficient of amplifying the pressure differential control valve orifice. These parameters affect the stability, controlling and readjustment time in the hydraulic circuit differently. A functional including the values of controlling time , σ controlling and losses in the pump controller was used as an optimization criterion. The optimization has been made according to the developed mathematical model applying the method developed by I. Sobol and R. Statnikov. During the optimization each controller parameter changed on 3 levels. 81 tests were made and the best combination of controller parameters for the optimization criterion was determined. The following hydraulic circuit operation values were reached under the optimal values of parameters = 1.0·10-6 m2, = 1.0·10-3 m, = 1.2·10-6 m2, = 10·10-3 m: = 1.1 с, σ = 32 %, = 0.82 kW that comply with the requirements towards hydraulic circuits of mobile machines.

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».

Control of mobile equipment for the processing of marine shaft lines

The purpose of the research is to develop solutions for mobile equipment control in the processing of marine shaft lines; to solve the issues of geometric accuracy of processing; to create a corrective program to address the issues of accuracy of the geometric parameters processing; to give reasons for the application of linear electrohydraulic step drive (LEHSD) in mobile equipment control. The analysis of schemes and mathematical dependencies for calculating the trajectory of the tool movement of a mobile machine when processing shaft lines is carried out; the choice of the optimal zone for finishing the shaft line, taking into account the beats. The object of the study is a ship shaft line. The paper presents an original scheme of rotation of the shaft line section, as well as schemes for changing the position of the shaft line during processing; justifies the possibility of using a linear electrohydraulic step drive (LEHSD) with a corrective program for processing taking into account automatic measurements and a specified error.

Investigation of tribological characteristics of brake pairs elements of mobile machine

The subject of the experiments was the tribological properties of typical brake pads and disc characteristics. For the experiment was used Grey Cast Iron brake disc and semi metallic, low steel quantity and ceramic brake pads. The breaking process was imitated. The experiment was conducted at 0.75, 1.25 and 1.76 m/s sliding speed using 0.85 MPa contact pressure. The experiments lasted 10 minutes. The results of the experiments showed that best tribological characteristics have ceramic brake pads, despite the fact that brake disc temperature rapidly increase the with ceramic brake pads, but the friction coefficient (and braking torque) was the best. Semi metallic and low steel braking pads had very similar friction coefficient values, but wear and disc temperature values were more dissimila

OVERVIEW OF MOBILE MACHINE DESIGNS FOR LARGE-SIZED PRODUCTS

The repair of large-sized products without a specialized repair facility is usually not available due to the impossibility of ensuring high accuracy when performing mechanical processing. Nevertheless, dismantling and moving large-sized items to the repair facility significantly increase the downtime of the equipment being repaired, or it is technically impossible to perform. Specialized machines that are used to repair large-sized items in such facilities are unique and expensive. They are heavily loaded and this can lead to various risks associated with the timing of the repair. Therefore, it is necessary to reduce the time required for dismantling, moving and processing large-sized items. In this regard, the rejection of these operations in favor of the use of mobile machines will significantly reduce the time and cost of repairs of large equipment. The article discusses domestic and foreign achievements in the field of mobile machines and systems that are used for maintenance and machining of large-sized products on site without dismantling. A number of designs of specialized mobile machines for use in various industries are described.