Substantiation of the influence of changes in the coefficient of axle distribution of braking force on the handling of a passenger car

The article considers the change of the radius of the instantaneous center of rotation of a car moving along a curved trajectory during braking, taking into account the lateral input of the wheels of both axles of cars, both equipped with electronic tracking systems and not equipped with such. A criterion for assessing the controllability of cars moving on a curved trajectory in a braked state, by comparing the ratio of the current speed of the car to the longitudinal base with the ratio of the coefficients of lateral tire input to the product of the longitudinal base of the car, mass and cosines. It is established that the radius of instantaneous rotation of the longitudinal axis of the car moving along a curved trajectory during braking depends on the speed of the center of mass of the car, the coefficient of axle distribution of braking force, physical characteristics of applied tires, steering wheel angle and design and weight parameters. As a result, it allows you to set controllability. The authors obtained dependences that will create new algorithms for the operation of modern electronic control systems for stabilizing the longitudinal axis of a braked car, taking into account the speed of the car, its design and weight characteristics, the main characteristics of its braking system (coefficient of axle braking force distribution), physical characteristics used tires on wheels and connect them to the angles of the steered wheels, controlling the deviation of the longitudinal axis, which allows the driver to maintain the possibility of quite sharp maneuvers directly in the braking process, moving along a curved trajectory.

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.

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.

Application of ABS Regulator Solenoid Valve Control

In the air brake system of the vehicle, the electromagnetic valve of the brake regulator belongs to the anti-lock brake system. In case of an emergency, the wheel is prevented from being locked and slipped during braking, and the most suitable braking force is applied to each wheel, so that the adhesion force [1] of the tire to the ground is fully utilized, which plays a vital role in improving the safety of the vehicle. In ABS anti-lock system, the regulation of solenoid valve plays an important role. This paper analyzes and applies a kind of solenoid valve control.

Numerical investigation of a high-pressure gas medium preionization by runaway electrons

A comparative simulation of the generation and acceleration of runaway electrons in the discharge gap during the initiation of the discharge by nanosecond and subnanosecond pulses is carried out. We used a numerical model based on the PIC-MCC method. Calculations were carried out for N2 6 atm pressure. Numerical simulation of a formation process of the electron avalanche initiated by an electron field-emitted from the top of the cathode microspike was carried out taking into account the motion of each electron in the avalanche. Characteristic runaway electron trajectories, runaway electron energy gained during the motion through the discharge gap, times required for runaway electrons to reach the anode were calculated. We compared our results with calculations using well-known differential equation of electron acceleration using braking force in Bethe approximation. We solved this equation also for braking force based on real (experimental) ionization cross section. The reasons for the discrepancy in the calculation results are discussed.

Improving measuring line parameters of the UIC test bench

This article deals with the description of the management of variable braking force at the request of multi-level braking on certification test bench UIC. The device is used to analyze the frictional properties of rolling stock brake accessory components. The introduction of the article describes and approaches the function of the measurement and control process. Based on the UIC standard, the requirement for variable braking force for multi-level braking is described. The conclusion of the article is devoted to evaluating the accuracy of measured data and analyzing undesirable phenomena.

Measurement analysis of braking forces and braking coefficient at different loads of a passenger vehicle

This paper presented an analysis of the braking force efficiency, i.e. its intensity in the case. It presented an analysis of the efficiency of braking forces, i.e. their intensity in the case when the load of a passenger vehicle was gradually changing. The change in the load of the vehicle was done by varying the number of passengers in it from one to five which is a feature of a higher number of M1 category vehicle. By increasing in the number of passengers the weight of the vehicle varied by approximately 75kg per passenger. The experimental test was performed in the technical inspection station, i.e. on standard rollers for the brake system testing. The test results shown that the relative difference of braking forces occurred on the front axle during intensive braking and that the braking coefficient was the lowest of about 69.94% in the case when only the driver was in the vehicle. It increased with increasing load, i.e. the number of passengers in the vehicle up to 85.91% and then dropped by increasing the rear passenger behind the driver and front passenger to 80.43% which can affect the stability of the vehicle when braking in the event of a dangerous traffic situation.

Research on the Development of the Welding Reconditioning Procedure for Friction Liner on the Passenger Coaches

SNTFC CFR SA owns a fleet of 841 passenger coaches, which it maintains through usual overhauls and repairs at high safety levels provided by the national railway regulations and instructions. One of the most important systems of a wagon is the braking system. One part of this system is also the friction liner, its role being to support the friction gasket that applies the braking force on the brake disc. This friction liner is made of cast iron and is a component included in risk class 1A, according to OMT 290/2000, with a service life of 10 years. Depending on the degree of wear and safety in operation, one may decide to replace it with a new part or intervention to return to the initial dimensional shape. Considering the importance of this friction liner, a very precise analysis must be performed, and this should show the steps necessary to reintroduce the part into operation. The performed analysis is a welding reconditioning procedure, which must be applied with precision. The paper indicates all the stages and results we looked for by applying a reconditioning procedure for the particular situation of using the welding process by means of tables / graphs and of results obtained as of detailed works.

DRAG ANALYSIS OF AERODYNAMIC BRAKING SYSTEM FOR THE HYPERLOOP POD

This research presents the results of the aerodynamic brake plates mounted on the hyperloop pod, on a fluid flow field, and overall braking force under the same velocity with different angle deployment of the brake plates. Aerodynamic brake plates are designed to generate the braking force by increasing the aerodynamic drag when It was deployed against the fluid flow, in this research three plates are used one is a horizontal plate mounted on the roof of the pod and the remaining two are vertical plates which are mounted on the left and right side of the hyperloop pod. In this research to develop the case studies different combinations of angle deployment of the brake plates are used, the sixteen cases of hyperloop pods with different angle deployment of brake plates are designed by using CATIA VR-6R. the flow simulation was made by Ansys CFX software for sixteen cases of the pods with different angle deployment of the brake plates under the same velocity. This research founds that the aerodynamic drag force is a function of angle deployment of the brake plates under the same velocity, drag force can increase or decrease by changing the angles of the brake plates. the result shows that 2.4 times of drag force increased for a fully deployed angle of attack of the brake plates when compared with the the same pod with no brake plates shows us that employing the brake plate increases the drag force This outcome will provide a major contribution to the development of the aerodynamic braking system of the hyperloop pod. KEYWORDS: hyperloop pod, aerodynamic drag, 𝑘 − 𝜔 model, aerodynamic brake