TO THE MOVEMENT OF A FREIGHT TRAIN WHEN STOPS ON A PLAIN LAND OF RAILWAY SECTION

ABSTRACT

The results of the justification of the kinematic parameters of the movement of freight trains and electric traction locomotives without stops and with stops on a virtual flat section of the railway are presented. The set goal of the research was realized by traction calculations, based on the developed mathematical models for driving freight trains by one of the electric traction locomotives, which were based on the well-known differential equation of train movement. The results of the research are obtained in the form of tabular data, graphical dependencies and regression equations designed to determine the main indicators of the transportation work of electric traction locomotives on virtual and, identical to them, real flat sections of the railway, taking into account the kinematic parameters of the stopping process of freight trains.

АННОТАЦИЯ

Представлены результаты обоснования кинематических параметров движения грузовых поездов и локомотивов электрической тяги без остановок и с остановками на виртуальном равнинном участке железной дороги. Поставленная цель исследований была реализована тяговыми расчётами, опираясь на разработанные математические модели ведения грузовых поездов одним из локомотивов электрической тяги, основу которых составило известное дифференциальное уравнение движения поезда. Результаты исследований получены в виде табличных данных, графических зависимостей и уравнений регрессий, предназначенных для определения основных показателей перевозочной работы локомотивов электрической тяги на виртуальных и, идентичным им, реальных равнинных участках железной дороги с учётом кинематических параметров остановочного процесса грузовых поездов.

Keywords: research, result, freight train, electric locomotive, railway track, parameter, siding, analysis, station, time, speed, flat, virtual.

Ключевые слова: исследование, результат, грузовой поезд, электровоз, железнодорожный путь, параметр, разъезд, анализ, станция, время, скорость, равнинный, виртуальный.

Introduction

In Uzbekistan, the locomotive fleet is continuously replenished with new generation electric locomotives. The length of electrified sections of Uzbek railways is noticeably increasing. Therefore, the study and analysis of the operation of electric locomotives becomes a priority for the Joint Stock Company "Uzbekiston temir yo'llari".  Therefore, one of the main tasks is to increase the capacity of the electrified sections of Uzbekistan's railways.

Employees of the department "Locomotives and locomotive economy", Tashkent State Transport University, conduct theoretical and experimental research on the analysis and evaluation of the efficiency of the transportation work of electric traction locomotives, in real conditions, on various sections of railways.

Statement of the problem and methods of research

The purpose of the study is a theoretical substantiation of the kinematic parameters of the movement of freight trains, at a stop, at an intermediate and final station, of a flat section of the railway. It is necessary to consider different organizational, technological and technical operating conditions.

These studies are a logical continuation of the work of one of the authors of the article [1-3]. The basis of the developed algorithm was the methods of the theory of locomotive traction [4]. The material and technological conditions for organizing the transportation work of freight locomotives on a straightened track profile of the studied section of the railway are taken from [1,5].

The object of study is freight trains with different weights and the same number of train axles, three-section mainline freight electric locomotives of the 3VL80^S series, and a straightened track profile.

The subject of the study is the kinematic parameters of the movement of a freight train, taking into account the analysis of its braking, at the intermediate and final stations, for a constant number of axles of the train.

In previous works, one of the authors of the article, were described: design features; technical specifications; traction and current characteristics; energy and performance indicators of the electric locomotive 3VL80^S [6,8]. The characteristics of the straightened track profile of the flat section of the railway, element by element, are given in [2,3].

Research results

As a result of the analysis of the trajectory of the movement of a freight train with different masses of trains [1-3], it was found that on the flat section of the railway, the change in the speed of trains does not exceed ΔV = 10 km/h. The technological process of the implementation of the railway transportation of goods on a flat area proceeds at a uniform speed.

In table 1 and table 2, the numerical values of the kinematic parameters, the movement of freight trains, for each stage, without stops and with stops at intermediate stations, of the flat section of the railway, under different operating modes, of power energy systems of 3VL80^S electric locomotives, taking into account the time for deceleration - acceleration. In table. 1, the following designations are adopted: the “asterisk” sign is the time for the acceleration of a freight train from the departure station, which is adopted in accordance with the recommendations [4,6,9], and the “two asterisks” sign is the average travel time of a freight train for acceleration – deceleration in the process of movement with stops.

Comparative analysis of the data in table 1 and table 2 shows that for average values of kinematic parameters, the movement of freight trains with different masses and a constant number of axles of the composition, on a flat section of the railway, without stops, at an intermediate station, in relation to similar movement, with stops, provides:

• decrease in the total travel time of the train by 4.96 minutes and an increase in the technical speed of movement by 12.86 km/h with an average estimated time per stop of approximately 2.48 minutes;

• the values of the shares of movement in traction modes at 59.65 percent, and idling and braking at 40.35 percent;
• an increase in the share of driving in traction modes and a decrease in the share of idling and braking driving by approximately 3.75 percent.

Table 1.

Travel time of a freight train on hauls without stops and through the intermediate station for deceleration - acceleration

Table 2.

Time distribution of a freight train on the halls of the flat section A - C, electric locomotives 3VL80^S

On fig. 1 and fig. 2, respectively, shows the numerical values of the kinematic parameters during stops at intermediate stations. Histograms in fig. 1 and fig. 2 show the change in the distance that freight trains travel: in case of stops at intermediate and final stations; when braking; when accelerating at stations.

Figure 1. Path traveled by a freight train when braking and starting off at the intermediate station and the arrival station

On fig. 1 and fig. 2 marked: S_z' and S_z'' - the way of deceleration of the freight train, respectively, at the intermediate station, and the station of arrival in case of braking of the freight train; S_p' is the acceleration path of a freight train at an intermediate station when starting off; V_z' and V_z'' – the speed of the freight train at the beginning of braking, respectively, at the intermediate station and the arrival station; V_р' is the speed of the freight train at the moment of "surge" of the train's non-stop running at the intermediate station.

The deceleration path S_z' and S_z'' is the distance that the freight train travels from the start of braking (transfer of the driver's crane handle to the brake position) to the complete stop of the train. Acceleration distance S_p' is the distance traveled by a freight train from the moment it starts to move from its place at an intermediate station to the moment it completes its acceleration, that is, the "surge" of the train's non-stop running.

Figure 2. Freight train speed at the beginning of braking and at the end of the acceleration at the intermediate station and the arrival station

According to the path change histograms in fig. 1 and graphs of movement speed change in fig. 2 it can be seen that with an increase in the mass of a freight train in the case of its braking at an intermediate station and an arrival station, there is a decrease in the deceleration path S_z', S_z'' and the acceleration path S_p', as well as a decrease in travel speeds. The rate of change of these parameters (decrease) depends on the mass of the freight train.

The rate of change (increase or decrease) of kinematic parameters, the process of stopping at intermediate and final stations, on the route, and the speed of freight trains with each subsequent increase are given in table. 3. The mass reduction step of the composition is ∆Q = 500 tons. The rate of change of values is the ratio of the subsequent value of the parameter under consideration (path, speed) to the previous value, with a decrease in the mass of the train by a given step. For example: with an increase in the mass of the train from Q₁ = 2500 tons to Q₂ = 3000 tons, of a freight train, the rate of change of the deceleration path Sz' at the intermediate station will be 0.923 units, that is, S_z2' = 2.4 km: S_z1' = 2 .6 km = 0.923 units, and with a decrease in the mass of the train from Q₃ = 3500 tons to Q₂ = 3000 tons of a freight train, the rate of change in the speed of its movement Vр' at the end of acceleration at the intermediate station will be 1.045 units, that is, V_р2' = 93 km/h : V_р3' = 89 km/h = 1.045 units.

Table 3.

Kinematic parameters of the stopping process of a freight train on the flat section of the railway, electric locomotives 3VL80^S

The dynamics of change in the kinematic parameters of braking and speed in the range of changes in the train mass from Q₁ = 2500 tons to Q₃ = 3500 tons, and the accepted variation interval ∆Q = 500 tons, of a freight train, is described by the following analytical dependencies:

S_z' deceleration path of a freight train when braking at an intermediate station, km

S_z' = 0.075Q2 - 0.425Q + 2.95 R2=1.0                                   (1)

Deceleration path S_z'' of a freight train when braking at the end station, km

S_z'' = 0.125Q2 - 0.725Q + 3.32 R2=1.0                                    (2)

Acceleration path Sp' when starting a freight train at an intermediate station, km

S_p' = - 0.1Q2 + 0.25Q + 3.1 R2=1.0                                   (3)

Speed V_z' at the beginning of braking of a freight train at an intermediate station, km/h

V_z' = - 2Q + 98 R2=1.0                                                (4)

Speed V_z'' at the beginning of the braking of a freight train at the end station, km/h

V_z'' = - 0.5Q2 + 0.5Q +92 R2=1.0                                         (5)

Speed V_p' at the end of the acceleration of a freight train at an intermediate station, km/h

V_р' = 0.5Q2 – 6.5Q + 104 R2=1.0                                        (6)

In formulas (1) - (6), a sufficient value of the approximation reliability R² = 1.0 is given (the necessary reliability condition is R²≥0.8), and the value Q_i = 1.2.3 indicates the traction calculation option.

The analysis of the above equations shows that the dynamics of the parameters, depending on the change in the mass of the train, is described by a polynomial of the second degree, with the exception of the speed V_z', at the beginning of the braking of the freight train, at the intermediate station (linear dependence).

Conclusions

As a result of the research conducted by the authors of the article, the kinematic parameters of the movement of freight trains and electric locomotives 3VL80^S were substantiated in the form of tabular data and graphical dependencies. Equations are given to determine the main kinematic parameters of the transportation operation of the investigated electric traction locomotives, including the stopping process, on real flat sections of the railway. The obtained kinematic parameters are consistent with the previous studies of the authors of the article [1-3, 5, 6, 7], and can be used in the operation of locomotive depots, Uzbek railways, to organize the operation of electric locomotives of the 3VL80^S series on flat areas.

Reference:

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