BRAKING EFFICIENCY OF QUARRY TRAINS WITH SIX-BOGIES DUMP CARS OF THE INCREASED AXIAL LOAD UP TO 27.7 TF

Improving the technical level of railway transport of industrial enterprises is expressed in the introduction of advanced types of traction (locomotives and electric locomotives), four and six-axle specialized cars, including self-unloading, automation and telemechanics. To increase the productivity of quarry trains at PJSC "Kryukiv Railway Car Building Plant" a six-axle dump car model 33-7141 for quarry railway transport was designed. The car is designed for transportation from quarries of open cut hard rocks, ore and other bulk and lump cargo with density (1.75-4.0) t/m3, as well as mechanized unloading on dumping sites or crushing units of opencast mining. A distinctive feature of innovative dump cars from typical ones is the increase of cargo weight by 10 t and axial load to 271.6 (27.7) kN (ts). In this regard, the issues of assessing the braking efficiency of a quarry train with innovative dump cars that meet the requirements for railway industrial transport are becoming relevant. The article presents the study results of the braking efficiency of a quarry train composition of 10 and 14 cars. Locomotive TEM7 and unit OPE1AM with one and two motor cars were considered as traction units. The maximum permissible speeds were determined in a given range of slopes of the railway track, and the maximum possible descent was set provided that the braking distance does not exceed or will be equal to 300. As a result of research, it was found that the maximum allowable deviations ranged from 34 ‰ to 38 ‰ depending on the number of cars and traction units. The speed of trains with innovative dump trucks on the site is 42 km/h. Key words: dump car, tipping wagon, maximum slope, permissible speed, braking distance, traction unit.

ASPECTS OF BRAKING EFFICIENCY CRITERIA FOR FREIGHT WAGONS UNDER THE LATEST RULES OF HOST 34434-18

The paper deals with the analysis of the braking efficiency criteria for freight trains formed with wagons that have increased axle load up to 294.3 kN (30 ts) when moving at speeds up to 120 km/h inclusive. Increasing the efficiency of freight trains by increasing the technical and economic performance of cars by increasing the axial load to 294.3 kN (30 ts) and train speeds up to 160 km/h led to the development of technical requirements and rules for braking systems set out in HOST 34434-18. According to the new rules and requirements, the following are accepted as criteria for the braking efficiency of freight wagons, that is, up to the maximum values of the braking distances of the freight train on the site in the specified intervals of speeds of axial loads; calculated coefficients of force of pressing of composite blocks on wheels at braking; the pressing force of the composite pads on the axis in terms of cast iron pads. The calculation of the maximum allowable value of the braking distance of the freight train is performed based on the actual pressing forces and the actual friction coefficients. The paper shows that the specific braking forces obtained using the actual pressing forces exceed the calculated specific braking forces using the calculated coefficients. Based on the above-mentioned, it is concluded that the braking efficiency criteria with reference to the maximum allowable values of the braking distances and the calculated coefficients of the pressing force have a significant discrepancy between each other. It is proposed to use the actual pressure force coefficients instead of the calculated coefficients to assess the braking efficiency of the freight train. The paper presents the permissible values of the actual force values of pressing the pads on the wheels for wagons with axial load (230.5 - 294.3) kN at speeds up to 120 km/h inclusive, for which the braking distance criterion of the freight train is observed. Key words: criterion, braking efficiency, freight train, axial load, braking distance, specific braking force, calculated coefficients, actual coefficient.

DETERMINATION OF FREIGHT WAGON PARAMETERS ACCORDING TO THE SPECIFIED CRITERIA OF THE TRAIN BRAKING EFFICIENCY (four-axle gondola cars, covered cars, platforms, dump cars)

The lack of normative values of the actual coefficients in the new rules of HOST 34434-2018 do not allow to implement and determine the optimal characte-ristics of the brake according to pre-accepted conditions of braking efficiency (braking distance), which causes uncertainty in solving this problem. The uncertainty is that the choice of characteristics of the braking system of the freight wagon has to be done by searching a large number of options. In this regard, the paper provides tools for determining the actual pressing force of the brake pads on the wheels, which complies with the specified braking performance of the freight train. As a tool, universal formulas are used in the form of a power relationship between the actual force of the brake pads and the braking distance of the freight train. The coefficients of universal formulas are obtained on the basis of computer modeling. Numerous examples show that the error in the use of universal formulas in calculation studies does not exceed 1% compared with the calculation method according to HOST 34434-2018. The values of the actual coefficients depending on the axial load of the wagon and the speed at which the braking distances of the freight train satisfy the normative minimum allowable values are given. It is shown that calculation studies performed according to the universal formulas in the EXCEL environment allows to fully automating the computational process. A method for determining the gear ratio of the brake lever of a freight wagon, according to which the specified braking efficiency is performed, is proposed. The proposed procedure allows you to perform a variety of studies to select the optimal parameters of the braking system of freight wagons that meet the specified requirements of braking efficiency, and greatly facilitates the calculation studies. Key words: аctual coefficient, braking distance, speed, axial load, power dependence, coefficients, gear ratio.

ALGORITHM FOR DETERMINATION OF BRAKE EFFICIENCY OF INDUSTRIAL RAILWAY TRAINS

The main differences between the operating conditions of industrial railway transport from the main-line ones, which feature the performance of technological transportation, i.e., the transportation of goods within the local boundaries of enterprises (domestic technological transportation), and import (export) of goods to other modes of transport (external transportation). Industrial railway transport plays an important role at mining enterprises, as the working conditions of these enterprises are not constant and getting continuously more complicated during the entire period of field development. In this regard, one of the most important factors in ensuring the train safety is the braking efficiency. The calculation of the braking efficiency of a quarry train is performed according to special rules, and the parameters of the braking process that affect the braking distance are set by coefficients. As an estimated characteristic of braking efficiency for industrial railway transport, the maximum speed is taken, at which the braking distance should be no more than 300 m, regardless of the magnitude of the slope of the railway track. For the first time it is proposed to determine the allowable speed by the iterative method using a correction factor, the choice of which is due to the fact that the relationship between speed and braking distance is described by a quadratic function. The calculation showed that in five iterations the difference between the calculated and normative values of the braking distance of 0.01 m (1 cm) is achieved, which indicates the efficiency effect of the proposed determination procedure. The software allows you to automatically perform calculated studies for a given range of values of the slopes. The results of the train calculation in a specified range of slope values are given, as well as an analytical expression for determining the maximum speed for a given arbitrary slope value. Key words: allowable speed, braking distance, iterative process, correction factor, algorithm.

AN APPROACH TO EVALUATION OF FREIGHT TRAINS BRAKING EFFICIENCY BY THE RESULTS OF EXPERIMENTAL STUDIES IN COMPLIANCE WITH HOST 34434-2018 REQUIREMENTS

The approach of experimental study of the freight trains braking efficiency using computer simulation based on the implementation of the simulation model in the form of a differential equation of the wagon motion during braking, is proposed. The methodology of experimental studies is based on universal formulas for power-law dependences of braking parameters. The braking efficiency is evaluated by the use of computer software packages written in VBA (Visual Basic for Application) in Excel. The software package al-lows you to increase the automation of testing, the accuracy of calculations, to reduce the time for testing, and also minimize the number of errors caused by the human factor. The presented methodology significantly extends the number of parameters of the braking process used to analyze the braking efficiency of a freight train based on the results of running braking tests: actual values of braking coefficients; braking distances of a freight train not only on the site, but also on normalized gradient descents for a given number of wagons in the train, taking into account the increase in the braking force along the wagons in the train formation; actual values of wheel and rail adhesion coefficients during braking; the deceleration of the freight wagon and the train during braking, as well as the braking time. Examples of computational and experimental studies of a freight train with tread brake are given. A comparative analysis of experimental and computational studies demonstrates sufficiently satisfactory matching of their results. Key words: freight train, braking distance, braking speed, braking coefficient, increase in braking force, mathematical model, trend line, braking wave.

Vehicle Cruise Braking Distance Calibration based on Embedded CNC System

Most of the vehicle cruise braking calibration algorithms only calibrate the distance, ignoring that the driver cannot control the vehicle braking in time under fatigue conditions. Therefore, an embedded CNC system is added to the vehicle cruise braking distance calibration algorithm to control the vehicle speed and prevent the vehicle from rear-end collisions. At this time, the CNC system uses incremental control to control the vehicle cruise braking. The reaction time model and braking distance calculation model under control increment are established. At the same time, air resistance and rolling resistance of cruise braking distance parameters are calculated. Cruise braking distance calibration is completed by integrating the two models, CNC system control increment, air resistance and rolling resistance parameters. The experimental analysis shows that the calibration error of the algorithm is within ±30cm and the calibration accuracy is high, which meets the practical application standard of cruise braking.

Experimental Validation of LiDAR Sensors Used in Vehicular Applications by Using a Mobile Platform for Distance and Speed Measurements

LiDAR sensors are needed for use in vehicular applications, particularly due to their good behavior in low-light environments, as they represent a possible solution for the safety systems of vehicles that have a long braking distance, such as trams. The testing of long-range LiDAR dynamic responses is very important for vehicle applications because of the presence of difficult operation conditions, such as different weather conditions or fake targets between the sensor and the tracked vehicle. The goal of the authors in this paper was to develop an experimental model for indoor testing, using a scaled vehicle that can measure the distances and the speeds relative to a fixed or a moving obstacle. This model, containing a LiDAR sensor, was developed to operate at variable speeds, at which the software functions were validated by repeated tests. Once the software procedures are validated, they can be applied on the full-scale model. The findings of this research include the validation of the frontal distance and relative speed measurement methodology, in addition to the validation of the independence of the measurements to the color of the obstacle and to the ambient light.

Testing the Impact of Braking Algorithm Parameters on Acceleration and Braking Distance for a Suspended Monorail with Regard to Acceptable Travel Speed in Hard Coal Mines

Increasing the maximum speed limit of suspended monorails, which became a very popular means of auxiliary transport, is one of the aspects of improving the efficiency of work in underground coal mines. It is especially important to enable higher (than allowed by the law) travel speed, when moving the crew to and from the workplace, which is often very distant from the shaft, and can take more than one hour of travel. Increasing this speed will make it possible to extend the effective working time of miners, which should have a positive impact on the economics of the mine. However, driving at a higher speed is also associated with increased risk of a negative impact of dynamic overload to people, e.g., during emergency braking of the suspended monorail. The concept of sequential emergency braking was developed in order to avoid excessive deceleration affecting passengers and the operator of the monorail, as well as to minimize the dynamic loads acting on the rail suspensions and on the roadway support frames, which could cause serious accidents. The developed assumptions with regard to the new method of braking are innovative in the area related to hard coal mining, where there are currently no such solutions. According to the principles of the developed concept, the total braking force was divided into two stages. The activation of the second stage depends on the deceleration measured after the time delay from activation of the first stage of braking. We present the results of the numerical simulations, which aimed to analyze the impact of changing the parameters of the braking algorithm on the braking deceleration, the braking time, and the braking distance. The possibility of changing the braking force and downward emergency braking on a high inclination angle were also taken into account during the numerical simulations. Use of the developed emergency braking algorithm enables the optimization of this process at a higher speed than is currently used. This aspect is also very important in increasing the safety for people travelling at a higher speed limit. The numerical simulations provide knowledge for safety in terms of the dynamic overload during emergency braking, without injury risk to miners or damage to equipment.

Alingment of braking performance for truck and trailer as an important factor in road construction

Alingment of braking performance of truck trailer is an important parameter that affects its braking stability. This shows particular in critical situations or during braking on a surface with reduced adhesion. Alingment of braking performance can be automatic, which is one of quality of electronical brake systems. Further on, can be forcible, which is being executed during service a diagnostic work.This contribution is focused on analysis alingment of braking performance. Describing technical conditions, internal and external factors which affect it. Due to magnitude of this problematics, is in this article evaluated the optimization of braking affects truck trailers in the start-up phase. The analysis of the process – start-up braking effect has justification from the reason, that has primary influence on the stability truck trailer during braking and this can be the cause of collision situations or also traffic accidents. The parameter of alingment of braking performance has a primary influence on the braking stability of the truck trailers, which significantly affects road safety and is also important for the economy of the truck trailers. your abstract here… The abstract should include the purpose of research, principal results and major conclusions. References should be avoided, if it is essential, only cite the author(s) and year(s) without giving reference list. Prepare your abstract in this file and then copy it into the registration web field. Braking distance is an important factor in the road construction. Therefore, it must be taken into account when designing these buildings.

Development of automatic system for Unmanned Aerial Vehicle (UAV) motion control for mine conditions

Underground mining operations are connected with significant risks of technogenic accidents, which can be catastrophic. Mitigating the consequences of such phenomena directly depends on the reliability and efficiency of information about the state of parameters of many technological processes, mine workings and facilities located in them. At failure of standard systems of industrial telemetry in conditions of underground mining the creation of new information channels and places of information measurementbecomes practically impossible in case of emergency situation development. This predetermines necessity of use of essentially new systems of gathering and transfer of the information, based on robotized autonomous complexes. The task of acquiring reliable information about the situation in an emergency mine working with the help of drones (unmanned aerial vehicles or UAV) in order to make rational decisions in the course of the rescue operation is quite relevant. The aim of the paper was to develop a system of automatic control of an unmanned aerial vehicle (UAV) movement in confined space of a mine working, with significant perturbations of the mine air flow. The mathematical model of UAV movement in mine conditions, based on Euler angles or quaternions, was substantiated. The method of positioning through triangulation with the use of radio beacons was accepted as the basic method that allowed to determine the current position of an UAV. It was proposed to solve the problem of creation of the automatic system for an unmanned aerial vehicle movement control with the use of a hierarchical multiloop control system. The route planning algorithm was formed on the basis of the Dijkstra algorithm. For this purpose, discretization of the future motion space was performed, a labeled connected graph was constructed, on which the arc weights were the distances between the route points. A simulation experiment was implemented. The average deviation from the planned trajectory when flying at a speed of 10 m/s with payload mass up to 0.6 kg did not exceed 1 m, and the maximum deviation was unacceptably large. When flying at 6 m/s with payload mass up to 0.6 kg the average deviation did not exceed 0.3 m, and the maximum deviation, 1.2 m. The results of simulation of movement along the route towards the disturbing mine airflow showed that the control system allowed the UAV with payload of 0.6 kg to withstand the oncoming flow up to 8 m/s. It was obtained that with payload mass of 0.6 kg, the braking distance does not exceed 6 m if the UAV had a speed of 6 m/s, and the braking distance does not exceed 12 m at the speed of 10 m/s. The performed simulation studies confirmed the operating capability of the developed system for automatic motion control.