Contemporary design of the freight wagons requires lightweight and compact design of all subassemblies and components (e.g. bogies, brake systems etc.). Because of that several manufacturers of railway brake systems have developed a compact brake system having all major components located within bogie. This system despite the more complex construction than standard have more advantages (lower mass, reduced air consumption, higher efficiency of brake rigging etc.) This paper presents results and conclusions obtained by testing of two freight wagons of the same type equipped with classic brake system and compact freight car brake system (CFCB). The testing included brake performance test i.e. stationary test and slip brake test

Milković, Dragan

Radulović, Saša

Simić, Goran

Vukšić Popović, Marija

machinery

1 University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, sradulovic@mas.bg.ac.rs 2 University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, dmilkovic@mas.bg.ac.rs 3 University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, gsimic@mas.bg.ac.rs 4 High Railway School of Vocational Studies, Zdravka Čelara 14, Belgrade, marija.vuksic.popovic@vzs.edu.rs  21 COMPARISON OF BRAKE PERFORMANCES OF FREIGHT WAGONS WITH THE CLASSIC BRAKE AND COMPACT FREIGHT CAR BRAKE Saša RADULOVIĆ 1 Dragan MILKOVIĆ 2 Goran SIMIĆ 3 Marija VUKŠIĆ POPOVIĆ 4 Abstract – Contemporary design of the freight wagons requires lightweight and compact design of all subassemblies and components (e.g. bogies, brake systems etc.). Because of that several manufacturers of railway brake systems have developed a compact brake system having all major components located within bogie. This system despite the more complex construction than standard have more advantages (lower mass, reduced air consumption, higher efficiency of brake rigging etc.) This paper presents results and conclusions obtained by testing of two freight wagons of the same type equipped with classic brake system and compact freight car brake system (CFCB). The testing included brake performance test i.e. stationary test and slip brake test. Keywords – railway, bogie, brake, testing.1. INTRODUCTIONDevelopment of the freight cars goes toward lightweight design (the minimum tare mass) and to the increased speed.  Consequently, manufacturers started to develop compact brake systems for freight cars, in which the complete system is located within bogies. Such systems have lower mass and take up less space in comparison with standard brake systems. Obligatory application of the composite brake shoes type K accelerated development and introduction of the compact brake systems, because their higher friction coefficient, compared to cast iron shoes, made possible massive use of one-sided braking shoes. In this paper we presented brake performance obtained by calculations and tests of the two rail cars type Falns equipped with standard brake and compact freight car brake (CFCB). 1.1. Compact freight car brake characteristics The CFCB makes the operation of freight cars increasingly economical and efficient [1]. Due to its modular design, the CFCB is reduced in weight, simple to install and reduces costs. It offers low maintenance and low air consumption while being highly efficient and delivering low life-cycle costs. This leads to an increased performance, which brings benefits to both, vehicle manufacturers and the operators. The main advantages of CFCB are: • Optimum  kinematics• Modular design (block force is adjustable bychanging the internal ratio, without changinginstallation space or interface to the bogie andreduced installation time)• Low noise (use of steel-rubber-steel sleeves)• Low LCC• Low air consumption• Can be equipped with bogie-mounted and carbody-mounted manual parking brake• Low weight (4-axle wagon weight isdecreased for cca. 1 t)• Preassembled and ready to install• High efficiency (brake rigging efficiency iscca. 0.95 and does not change between twomaintenance inspections and it is independentof brake cylinder pressure• Low maintenance (there is no maintenancebetween the revisions).RAILCON ’18       COMPARATION OF BRAKE PERFORMANCES OF FREIGHT WAGONS… 22 2. TEST WAGONSFigure 1 shows analyzed freight wagon type Falns. Fig.1. Wagon type Falns Main characteristics of wagon are [2], [3]: • Vehicle mass (empty): 20800 kg• Vehicle mass (loaded): 90000 kg• Number of axles: 4• Bogie type: Y25• Axle distance within bogie: 1800 mm• Wheel diameter: 920 mm• Maximum speed: 120 km/hOne wagon is fitted with a classic braking system and the other with a CFCB (Fig. 2).  [1]                         Fig.2. CFCB Knnor Bremse Tab.1. Brake cylinder pressure Classic brake CFCB Brake cylinder pressure bar Empty wagon 1.36 1.09 Loaded Wagon 3.80 3.60 Brake block force kN Empty wagon 8.36 7.31 Loaded Wagon 29.41 28.84 Both wagons brakes are with automatic change of brake force vs. wagon mass and equipped with composite brake shoes type K. Wagon with CFCB system had the maximum brake cylinder pressure adjusted to 3.6 bar unlike 3.8 bar regularly used with standard freight brakes. Lower pressure causes reduction of wear of the shoes. On the basis of the calculation, the following parameters of the brake system were selected (Tab. 1). 3. COMPARISON OF BRAKEPERFORMANCE3.1. Brake rigging efficiency One of the basic difference between the classic and the compact brake is rigging efficiency. In the calculations its value for classic brakes is selected as 0.83 and corresponds to mean rigging efficiency between two inspections [5], while for CFCB this value is considered to be perpetual and equals 0.97. For tested wagons brake rigging efficiency was determined based on the brake cylinder pressure and the measurement of force between the shoe and the wheel (Fig.3). Fig.3. Brake shoe force tranducers The values of the measured efficiency are shown in Table 2 and the graphical diagram of the development of the brake force is shown in Figure 4.  Tab.2. Brake rigging efficiency Classic brake CFCB Calculated brake force (η=1) bar Empty wagon 10.07 8.45 Loaded wagon 35.43 33.58 Measured brake force kN Empty wagon 8.69 8.32 Loaded wagon 32.96 32.20 Effieniecy Empty wagon 0.86 0.97 Loaded 0.93 0.96 XVIII International Scientific-expert Conference on Railways                Serbia, Niš, October 11-12, 2018 23 Fig.4. Brake shoe force, axle 4, loaded wagon, with classic brake 3.2. Brake weight Braking performance of rail vehicles can be expressed via braked weight. Brake weight is the basic braking performance parameter expressed in integer numbers of tons. Brake weight of these wagons was determined based on the slip test according UIC 544-1. The first test results do not fulfill the minimum braking performance from CR TSI WAG 2013, table C.3 for the wagon equipped with the variable relayvalve.With nominal cylinder pressure 1.36 bar resulted in following results:  scorr=395 m, =138% for 100 km/h and scorr=505 m,  =147% for 120 km/h. where are: scorr – corrected stopping distance  - brake weight percentage.Also, at nominal designed cylinder pressure of 3.8bar in the partially loaded condition with m=59.7 t, first two tests resulted in following results:  scorr=405 m, =120.5% for 100 km/h  scorr=575 m,  =126.5% for 120 km/h  Measured brake weight percentages were above allowable values according to EN 14198. Brake cylinder pressure was decreased by using relay valve to 1.2 bar for empty wagon and 3.4 bar for loaded wagon. With new values of brake cylinder pressure was performed slip test and the following results were obtained (Table 3) where: m – wagon mass v – initial speed scorr – corrected stopping distance  – brake weight percentageB – brake weightBuic – rounded brake weight that will be marked onthe wagon. Tab. 3. Brake weight – classic brake Brake regime M V scorr,2 λ B BUIC[t] [km/h] [m] [%] [t] [t] P 20.8 100 432.1 112.3 23.4 23 120 616.8 116.6 24.3 24 59.70 100 491.6 97.5 58.2 58 120 682.3 103.6 61.8 62 89.85 100 699.3 65.6 58.9 59 Table 4 presents test results for the wagon with compact brake. Tab.4. Brake weight – compact brake Brake regime M v scorr,2 λ B BUIC [t] [km/h] [m] [%] [t] [t] P 20.84 100 474.6 101.3 21.1 21 120 650.3 109.6 22.8 23 59.8 100 476.1 101.0 60.4 60 120 668.4 106.1 63.5 63 90.05 100 698.8 65.6 59.1 59 As an illustration, diagrams for two recorded tests are shown in figures 5 and 6. In the graphics, following designations are used: pBP - brake pipe pressure pBC - brake cylinder pressure v - speed s - distance traveled The stopping distance was derived from the traveled distance data for each individual test, as a path traveled between the starting moment of pressure fall in main brake pipe to the moment when the speed reaches zero. Fig.4. Slip test, wagon with classic brake RAILCON ’18       COMPARATION OF BRAKE PERFORMANCES OF FREIGHT WAGONS… 24 Fig.5. Slip test, wagon with compact brake 4. CONCLUSIONBased on the results, it can be concluded and confirmed that due to the construction of the braking system, brake rigging efficiency of CFCB is greater than classic brake. In addition, by using composite brake shoes, it is mandatory to determine the brake performance by testing, due to the variation in the value of the coefficient of friction of these shoes. The conducted testing showed that it is necessary to perform the adjustment of the braking system in order to obtain satisfactory results. This could be done by changing the pressure in the brake cylinder or the brake rigging ratio. If there is need for changing brake rigging ratio, compact brake system has the advantage, because it is possible to be done more simpler, only by changing the internal ratio without changing installation space or interface to the bogie. Because of all these advantages, all leading braking equipment manufacturers have developed and upgraded their compact brake systems and their massive use is expected, primarily on new wagons. ACKNOWLEDGEMENT The authors express the gratitude to the Ministry of Education, Science and Technological Development, Republic of Serbia research grant TR 35006 and TR 35045. REFERENCES [1] Knorr Bremse Group catalog[2] Report of Brake performance test of Falns wagon withstandard brake system, No. 13.04-136, University ofBelgrade, Faculty of Mechanical Engineering,Laboratory of rail vehicles, Belgrade 2017.[3] Report of Brake performance test of Falns wagon withstandard brake system, No. 13.04-137, University ofBelgrade, Faculty of Mechanical Engineering,Laboratory of rail vehicles, Belgrade 2017.[4] S. Radulović, Influence of methods of measurementand data processing of the measurement signals todetermine braked weight in the of standard testmethods, Master thesis, Faculty of MechanicalEngineering in Belgrade, 2016.[5] International Union of Railways UIC Code 544-1:Brakes – Braking performance 6th edition, October2014.

Comparation of brake performance of freight vagons with classic brake and compact freight car brake

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Comparation of brake performance of freight vagons with classic brake and compact freight car brake

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