RECOMMENDATIONS FOR THE SELECTION OF PARAMETERS FOR SHUNTING LOCOMOTIVES

Shunting is an integral part of the partial process. In 1520 mm gauge countries, shunting operations are performed by outdated locomotives, which are being replaced by modern models; the technical parameters best match the conditions of the shunting work performed. The article analyzes recommendations for the selection of parameters of shunting locomotives and the actual indicators of their work. On the basis of this analysis, a requirement was made on the necessity of compulsory consideration of the operating conditions of the locomotive when determining its technical characteristics. As the main technical parameters of shunting locomotives, the tractive power and starting tractive force are taken and their influence on the duration of an elementary shunting movement of the "acceleration-deceleration" type is investigated. This approach advises the regulatory documentation for the organization of shunting work. Tha developed mathematical model allows to carry out research on the influence of tractive power and starting tractive force on the time of acceleration and deceleration. Calculations of the time of the train's acceleration are carried out with varying their mass and the slope of the track at different values of the tractive power starting tractive force. The calculations were carried out for the mass of compositions 1000...5000 Mg for the profile slopes equal to 0 and 1.5 ‰. The speed of the finish of acceleration was taken equal to 15 and 25 km/h. The thrust starting tractive force varied in the range of 150...300 kN, the tractive power 200 ... 1100 kW. According to the results of calculations, it was found that the reduction in the duration of the elementary shunting movement is more significantly affected by the power of the locomotive than by the starting traction force. The “saturation” effect was noted, in which a significant increase in power or traction force during starting does not cause a significant reduction in the acceleration time. In this regard, for shunting locomotives with AC traction drive, it is recommended to take a pulling force of an equal continuous traction force.


Introduction
Costs of shunting movement, which is integral element of transportation process, can reach 30-40% of all expenses of the railway station, and represent a significant part of the transport costs of industrial enterprises using shunting locomotives in the main technological process. Analysis of previous works shows that in operating locomotives , selection of the type of locomotive is widely used to perform specific shunting operations, which ensures the minimum fuel costs (Voronko, 2005;Verlan et al., 2012;Riabov, 2015). Obviously, the updating of shunting locomotives park, with deterioration estimated to 80 % (V "Ukrzaliznyitse" rasskazali, n.d.; Sirotenko, 2014), should take into account the existing experience, i.e. the key point when choosing technical parameters of shunting locomotives should be the compliance of the characteristics of locomotives with the nature of the work performed. Other important aspects of the shunting yards operations include train-to-yard assignments and optimi- ). An important element of rail operation is also the improvement of the structure of modern rail vehicles and the optimization of the railway infrastructure (Kukulski et al., 2019). In particular reducing the costs of rail operations can be reduced by energy recuperation in trains equipped with electric regenerative brake (Urbaniak et

Literature review
The approach used in the literature (Kamaev, 1981;Mikhalchenko et al., 2006) for the selection of parameters of shunting locomotives is to determine both the power and the chain weight. The traction power is determined by the expression = 3.6 ( 0 + + 0 ) where: is the mass of the combination of vehicles (in units of tons), 0resistivity, equals to 30 N/Mg, average accelerating force, equals to 50-80 N/Mg, 0resistivity from lifting, equals to 0-20 N/Mg, average speed during acceleration, equals to 7-8.5 km/h.
The chain weight of a shunting locomotive is determined by the expression where: Ψis coefficient of adhesion (grip index) in calculation speed equals to 10-16 km/h, coefficient of use of chain weight equals to 0.85-0.92 for locomotives with individual driving gears of wheel pairs.
For sorting locomotive the chain weight is determined by the expression where: 0 + is the resistivity to movement equals to 70 N/t for freight trains, average resistivity when climbing on the sliding part of the hill.
In both cases, the traction force is determined by the expression where: is the chain weight of the locomotive, g=9.81m /s 2free fall acceleration.
Traction force is the force of traction of long term mode of the locomotive operation. At the same time, the need to implement a long-term traction force is a natural requirement, and there are contradictions in the issue of determining the power of a shunting locomotive.
As an example, we consider the results of work (Sirotenko, 2014), which investigates the work of locomotive ChME3 at various stations of Kharkiv railway junction of Regional Branch «Pivdenna Zaliznytsia» of JSC « Ukrzaliznytsia». During the research, the duration of the locomotive operation at the position of the driver's controller was determined (Fig. 1).
Taking into account the traction characteristics of the diesel locomotive ChME3 (Fig.2) in the mode according to Fig.1, the locomotive mainly worked with a tractive power of 165 kW with a traction force, and in the mode according to Fig. 2-with  The different data on the operating modes of the diesel locomotive shown in Fig. 1 are explained by the fact that the shunting diesel locomotive performs various types of shunting work. And if in mode 2 the diesel locomotive operates practically with the rated power that in mode 1 -with a power approximately equals to 25% of the nominal. At the same time, information about the reason for switching on one or another position of the driver's control panel is not given, which does not allow identifying the operating modes in which the locomotive operates with the greatest duration. Studies of European scientists also show the need to take into account the operating modes of the locomotive when choosing its technical parameters. As shown in ( Objective. The above information clearly illustrates the need to take into account the operating conditions of a diesel locomotive when determining its technical parameters. Thus, it seems necessary to improve the technique of selecting parameters of shunting locomotives; the use of it allows for increasing the efficiency of the locomotive in real conditions of its operation

Simulation model of shunting movement
Today, in the study of various processes and objects, mathematical modeling is widely used, which makes it possible to assess the influence of various parameters on the properties and characteristics of the studied processes and objects. This is especially important, in particular, for railway transport, where in most cases the full-scale study of processes and phenomena is associated with serious energy and resource consumption. An example of a successful application of mathematical modeling is the simulation of train traffic which will be used in this work. As shown above, the tractivepower and the starting traction force can be taken as the characteristics of the shunting locomotive. Figure 3 shows typical traction and braking characteristics of the locomotive.
Fststarting traction force; Pktractive power at the wheel; Pbbreaking power at the wheel; Bmaxmaximum breaking effort The estimation of the effect of starting traction effort Fst and traction power on the wheel Pk on performing shunting operations is done. As a criterion, we will choose the duration of the half-flight, since this value is standardized by a number of regulatory documents and, obviously, the parameters of the locomotive must ensure compliance with regulatory requirements.
The duration of an elementary shunting movement (half-flight) is determined by the expression (Methodical instructions, 2003) where: the factor that takes into account the time required to change the speed of the locomotive by 1 km/h during acceleration, and the time required to change the speed of the locomotive by 1 km/h during braking, = 2.44 s/(km/h); Standards of time for half-flight of arrivals of shunting locomotives and rearrangements of cars and compositions are given in (Kamaev, 1981) in case that the half-flight consists of stages of acceleration, movement with admissible speed and braking. On the other hand, the travel time and the distance travelled are determined from the equations of train motion where: -is the speed of the shunting train; -traversed path; -specific tangential traction force of the locomotive; -total resistivity to train movement; -specific braking force. 1 , 2 -conversion coefficients that take into account the dimensions of physical quantities. When measuring the velocity in km/h, the time -in a second , mass -in tons, specific forcein N/kN and the traversed path -in meters, coefficients are equal: k1=0.033, k2=0.278.
Thus, the traction power on wheels and starting traction force should ensure the movement of the train of a given mass at a given distance in a time not exceeding the standard. In general, an elementary shunting movement consists of four stages: acceleration phase, movement with a set speed, movement with traction switched off (coasting), and deceleration phase (Fig. 4). Total duration of elementary shunting movement equals the duration of the individual steps where: 1 -is the acceleration time during which overcomes the distance l1; 2 -is the time of movement with the set speed during which overcomes the distance l2; 3 -the coasting time during which overcomes the distance l3; 4 -the braking time during which overcomes the distance l4.
the permissible speed during maneuvers; l1the distance where the train accelerates; l2the distance where the train moves at an acceptable speed; l3the distance where the train moves by inertia; l4the distance on which the train brakes where is starting traction effort in the range from zero to the speed at which the transition to the characteristic of constant power takes place, while is the tractive power of the locomotive (kW). In the case of electrodynamics braking the time of braking with electrodynamics brake can be determined in this method where: = + с -is the specific braking force of the electrodynamics brake, -the braking force on the wheel rim, -speed of the beginning of braking, -speed of the end of braking.
where is the maximum braking effort in the range from zero to the speed at which the transition to the characteristic of constant power takes place, -power on the wheel in the mode of electrodynamics braking.
The total braking time is determined by the formula where is the duration of braking by the pneumatic brake from speed to complete stop.
Duration of driving modes with set speed 2 and coasting 3 defined as the difference between the normative time and the total time of acceleration and braking. It is important to note that the rational distribution of the duration of the operation mode of the locomotive in various modes can be determined by optimizing its movement. Thus, the time of movement of shunting combination of railway cars depends on the basic parameters of the locomotive in the trailer and brake modes of work.
We perform estimation of influence of traction force when starting and tractive power for the duration of the acceleration. To perform this we do calculation by expression (8) where -is the speed of movement.
-basic resistivity of four-axle cars where 0 -is the axial load taken in the calculations equal to 23 Mg.
-additional resistance from the slope = 9.81 (15) where -is the slope in ‰.
Resistance to movement when starting off, driving on turnouts and curves are not taken into account in the calculations.   The increase of tractive power. significantly reduces the acceleration time, thus increasing the power with the greater traction force provides the greater reduction of acceleration duration. At the same time, the analysis of the dependences in Fig. 5-10 and the data in Table 1 shows that the change in the acceleration duration is non-linear. When the tractive power. changes from 200 kW to 400 kW, the acceleration duration is reduced by 2-3 times depending on the mass of the composition of railway cars. When the power is changed from 400 kW to 600 kW, the acceleration time is reduced by 10-15 %, and when the power is increased from 600 kW to 800 kW -by only 3-5 %. A change in the traction force influences the acceleration time in a similar way : when the traction force changes from 150 kN to 200 kN, the acceleration duration will decrease more intensively than when the traction force changes from 200 kN to 250 kN and from 250 kN to 300 kN. Fig. 11-22 show the dependences of the acceleration duration to a speed of 25 km/h on the traction force and tractive power on the horizontal section and on the slope of 1,5 ‰.

Results
-400 kW -600 kW -800 kW For example, for a train weighing 3000 tons (32 cars) with a half-flight length of 1500 m, the duration of a half-flight should not exceed 260 s. Having assumed that the traction force when starting off is 200 kN, after performing calculations using expression (16), we determine that the minimum tangential power should be 200 kW.
Accordingly, having analyzed the parameters of shunting operations as in the example, it is possible to determine the required power of the locomotive to perform all types of shunting operations.

Conclusion
The article shows the dependence of the required parameters of a shunting locomotive on the nature of maneuvers. It is noted that the operating shunting locomotives have excess capacity. To assess the power of a shunting locomotive, a method is proposed on the basis of criteria, limiting time of elementary shunting movement. This approach advises the regulatory documentation for the organization of shunting work.
According to the results of calculations, it was found that the time of acceleration and deceleration of a shunting train is more significantly affected by the power of a shunting locomotive than its starting traction force (limiting braking force). At the same time, a "saturation effect" is noted, in which a significant change in power or traction force when starting off does not lead to a significant change in the acceleration time.
The presence of the "saturation effect", when the acceleration time does not change significantly with a significant change in the thrust force, justifies the need to establish the thrust starting traction force to the thrust force of the continuous operation mode.
For locomotives with AC traction drives, this is extremely important, because it is not required to ensure the operation of traction drive components with loads higher than continuous ones. This reduces the 132 Kuznetsov, V., Lyubarskyi, B., Kardas-Cinal, E., Yeritsyan, B., Riabov, I., Rubanik, I., Archives of Transport, 56(4), [119][120][121][122][123][124][125][126][127][128][129][130][131][132][133]2020 weight, size and cost and increases the reliability of traction drives. Further research to determine the parameters of shunting locomotives should be carried out using the developed mathematical model. The purpose of such work may be to optimize the traction drive of the locomotive, which ensures the highest energy and resource efficiency when performing shunting work.