Academic literature on the topic 'Freight cars Wheels'
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Journal articles on the topic "Freight cars Wheels"
1
Lovska, A., and V. Ravlyuk. "IDENTIFICATION OF THE CAUSES OF SURFACE DEFECTS OF WHEELS OF CARS EQUIPPED WITH COMPOSITE PADS." Collection of scientific works of the State University of Infrastructure and Technologies series "Transport Systems and Technologies" 1, no. 40 (December 28, 2022): 102–20. http://dx.doi.org/10.32703/2617-9040-2022-40-9.
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The paper presents the results of the analysis of surface defects and faults of freight car wheels caused by frictional interaction with composite brake pads. It is established that the main influence on the thermomechanical behavior of freight car wheels is caused by thermal loads that occur during braking. In cases of thermal overloads, which arise mainly as a result of prolonged braking, the generation of stresses and deformations occurs, the consequences of which are the appearance of high-temperature local defects on the rolling surface of freight car wheels. These defects negatively affect the safety of trains and significantly increase the operating costs of railway transport. To determine the thermal stress state of the freight car wheel during braking, its calculation was carried out. As a calculation method, the finite element method was used, which is implemented in the SolidWorks Simulation software package. The temperature effect on the wheel during braking is determined to be permissible from the point of view of ensuring the strength of the wheel. The conducted research will contribute to the creation of recommendations for managing the temperature effect on the wheel, as well as improving the safety of trains and significantly reducing operating costs in railway transport.
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GAYIPOV, Aziz B., Ekaterina A. NARKIZOVA, and Tatiana M. BELGORODTSEVA. "Development of a refined methodology for calculating the balance of wheelsets and assessment of the need for wheels and axles for the wagon fleet of the Republic of Uzbekistan." Proceedings of Petersburg Transport University 18, no. 3 (September 30, 2021): 319–34. http://dx.doi.org/10.20295/1815-588x-2021-3-319-334.
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Objective: To develop a refined methodology for calculating the balance of wheelsets for a freight car fleet, apply it to determine the need for wheels and car axles for the freight car fleet in the Republic of Uzbekistan. Methods: Methods of combinatorial and statistical analyzes of the initial data were employed. Results: Methods for calculating the need for wheels and car axles are proposed, which makes it possible to determine the number of required wheel disks and finished axles for freight cars, depending on the forecast of the volume of freight turnover per year. Practical importance: The presented method for calculating the need for wheelsets can be used for a general analysis and assessment of the state of the production base in terms of shortcomings or excess of wheel disks and finished axles.
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Rozhkova, Elena. "EFFICIENCY ASSESSMENT OF BRAKING EQUIPMENT OPERATION IN INNOVATION FREIGHT CARS." Bulletin of Bryansk state technical university 2021, no. 3 (March 9, 2021): 46–53. http://dx.doi.org/10.30987/1999-8775-2021-3-46-53.
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The object of researches is brake systems of innovation freight cars. The work purpose consists in the assessment of braking system effectiveness in innovation freight cars and in standard ones at different operation modes.
The scientific novelty consists in the definition of the dependence of a slide block depth on the length of wheel pair skidding motion and braking distance dependence upon car speed. During the work there was carried out a retrospective analysis of cases with traffic safety violation connected with the formation of excessive sliders in freight cars in organized trains because of the violation of braking equipment normal operation. By means of the least-squares method there was obtained a linear equation defining the dependence of slider depth upon the skidding length of a wheel pair. As a result of the work there were defined parameters of defect formation on freight car wheels at their skidding, the calculations of braking system efficiency in different freight cars were carried out.
In the course of the analysis of freight car braking efficiency there are obtained equations of braking length in the accepted range of speeds at the beginning of braking for empty and loaded states. Minimum values of the design factor of braking block pressing in translation to a train length of 200 shafts in the empty state were 0.2256 for a speed of 40km/h, in the loaded one – 0.1781 for a speed of 120 km/h at the standard values 0.22 and 0.14 respectively. By means of calculations and experiments it is proved that composite braking block pressing force on a shaft exceeds 4tf/shaft, and that of cast-iron – 10tf. Accordingly, a car with the shaft load of 25 tf/shaft and accepted parameters of a braking system may be operated up to the speeds of 120 km/h inclusive without limitations.
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Smolyaninov, Alexander V., Vitaly F. Karmatsky, and Denis V. Volkov. "Regarding the life cycle of a freight railcar wheelset." Innotrans, no. 2 (2022): 35–41. http://dx.doi.org/10.20291/2311-164x-2022-2-35-41.
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The article notes that the main share of the costs for maintaining a fleet of freight cars falls on their current, depot and overhaul repairs. The cost of car repairing is significantly affected by the increase in prices for wheels, new and overhauled wheelsets. The paper explores ways to reduce these costs by increasing the life cycle of the wheelset and extending its service life. The proposals of a number of authors are analyzed to increase the hardness on the surface of the rolling wheel, to reduce the wear of the wheel crest, to make changes to the repair documentation, to introduce new IT services into the car repair production. Issues of the use of blockchain technology for management of the life cycle of wheelsets are considered. Proposals are given for participation of the university scientific community in solving the identified problematic issues.
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Kumar, S., and S. P. Singh. "Heavy Axle Load Wheel-Rail Contact Stresses and Their Tread-Crown Curvature Relationships." Journal of Engineering for Industry 111, no. 4 (November 1, 1989): 382–87. http://dx.doi.org/10.1115/1.3188776.
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This paper presents a theoretical/design analysis of wheel-rail contact stresses and geometries for U.S. freight cars of 70, 95, 100, and 125 ton freight capacities operating on various crown rails. After discussing various types of rail stresses, it is pointed out that the contact stresses are the major factor and the only parameter that enables a designer to improve or optimize the rail life and performance. In order to determine the most suitable diameters for the heavier cars, an engineering lower bound analysis of the contact has been completed. It uses in a two-dimensional Hertzian analysis, the field information of well worn-out wheel and rail contacts which are almost rectangular and of 1 in. width. The lower engineering bound values of maximum normal contact stresses for the 100 and 125 ton cars using wheels of diameters from 33 to 42 in. are given. This stress for the current 100 ton car with 36 in. diameter wheels is 98.35 ksi. To approach this value for the 125 ton car it is necessary to use 42 in. diameter wheels which is strongly recommended for the U.S. railroads. A Hertz theory based analysis of the contact stresses with varying wheel diameter, tread profile radius and rail crown radius for the 70, 95, 100, and 125 ton cars has been presented. Using the field information that the difference in radii of curvature of worn wheel and rail is approximately 5 in., choice of radii of rail and wheel profile curvatures is made so that the design radii difference is always 5 in. or more. Wheel diameter and wheel profile radius ranges used for this analysis were 33 to 44 in. and 15 to 35 in., respectively. The rail crown radius range was 10 to 30 in. It was concluded that a rail crown radius of 15 to 20 in. and wheel tread profile radius of 22 to 30 in. are good initial ranges for further analysis of design.
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Saidova, A. V., V. I. Fedorova, Yu B. Zhitkov, I. V. Fedorov, and A. N. Grishaev. "Assessment of the wear of wheels of freight cars under the existing standards for releasing three-piece bogies with an axle load of 23,5 tf from repair." PROCEEDINGS OF PETERSBURG TRANSPORT UNIVERSITY 18, no. 1 (March 31, 2021): 52–61. http://dx.doi.org/10.20295/1815-588x-2021-1-52-61.
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Objective: To assess the effect of the dimensions and tolerances of three-piece bogies of freight cars with a maximum static axle load of 23,5 tf when they are released from scheduled repair on the wheel flange wear in operation. Methods: For this purpose, drawing on a review and analysis of the literature in the field of wheel-rail system wear and the current requirements of guidelines for the repair of freight cars and their parts, design cases were formed to simulate a railway crew movement along a track of various designs with operating speeds, and the processes of wheel flange wear were studied using simulation computer modeling in the environment of the “Universal Mechanism” software package. Results: The parameters of freight car bogies which have the greatest impact on wheel wear have been determined. The quantitative values of the indicators of wheel wear for various cases of crew movement have been determined. The ways of reducing the wear of car wheels in operation by changing the dimensions and tolerances of bogies when they are released from scheduled types of repair are shown. Practical importance: The obtained results of the work commissioned by JSC “First Freight Company”are currently used to formulate requirements for the dimensions and tolerances of bogies when they are released from repair in order to establish the optimal parameters that would help to reduce the wheel flange wear in operation. In addition, they can be used in the developing new designs of freight car bogies.
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Fries, R. H., and C. G. Da´vila. "Wheel Wear Predictions for Tangent Track Running." Journal of Dynamic Systems, Measurement, and Control 109, no. 4 (December 1, 1987): 397–403. http://dx.doi.org/10.1115/1.3143873.
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Wear of wheels and rails is a problem of substantial magnitude for railways throughout the world. Efforts to control wear by using new wheels profiled to match worn wheels have met with a measure of success. Purely empirical approaches to this problem require years of effort before results can be assessed. This paper describes a computational method for predicting worn profiles. The method is applied here to freight cars running on tangent track, and it includes the capability to handle both stable and hunting running. The method has been evaluated with four different wear models, and it was found that the predicted worn wheel profiles are relatively insensitive to the selection of wear model. Results include predictions from AAR and CNA wheels running on new rail, and from a simulated unit-train operation.
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Safronov, Oleksandr, Yurii Vodiannikov, and Olena Makeieva. "DETERMINATION OF FREIGHT WAGON PARAMETERS ACCORDING TO THE SPECIFIED CRITERIA OF THE TRAIN BRAKING EFFICIENCY (four-axle gondola cars, covered cars, platforms, dump cars)." Railbound Rolling Stock, no. 23 (December 16, 2021): 101–10. http://dx.doi.org/10.47675/2304-6309-2021-23-101-110.
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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.
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Tankeev, S. V., A. E. Kolodin, V. B. Sverdlov, A. V. Nazarov, and M. A. Konev. "Investigation of the causes of damage to freight cars during disbanding on non-mechanized sorting slides and development of measures to prevent them." Herald of the Ural State University of Railway Transport, no. 2 (2021): 4–13. http://dx.doi.org/10.20291/2079-0392-2021-2-4-13.
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The damage assessment of freight cars during shunting and loading and unloading operations was made. The need to review the normative documents regulating the relationship between the owners of rolling stock, owners of non-public tracks and the carrier is noted. The reasons for formation of damage on the wheel pairs of freight cars when disbanding on low-power sorting slides are considered. The conditions for ensuring the deceleration of detachments on non-mechanized sorting slides without damaging the wheels are determined. The analysis of methods for ensuring braking on low-power slides is carried out. A method was chosen to ensure the wheel set rotation by introducing a third body between the rubbing surfaces during the braking of cars, which will take over a part of the resulting heat flow, reducing the temperature and increasing the coefficient of friction in the «wheel-rail» contact zone. A method is proposed to provide braking on the non-mechanized sorting slide during shoe braking by applying a friction compound to a non-working rail. Laboratory tests were carried out, which showed that the introduction of a friction additive can achieve the necessary coefficient of friction to comply with the standard parameters of deceleration of the car in the braking zone.
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Zub, I., and S. Sapronova. "NFLUENCE OF DEVIATIONS IN THE POSITION OF WHEEL PAIRS IN A FREIGHT-CAR ON THE GUIDING FORCES." Collection of scientific works of the State University of Infrastructure and Technologies series "Transport Systems and Technologies" 1, no. 40 (December 28, 2022): 67–77. http://dx.doi.org/10.32703/2617-9040-2022-40-6.
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The article puts forward a hypothesis according to which the violation of the nominal setting of wheel pairs in railway rolling stock carts is the main reason for the increase in guiding forces in the wheel flange contacts of the wheels of freight cars with the rails. Increased loads in wheel flange contacts are the cause of a number of other negative phenomena: increased intensity of wear (undercutting) of wheel flange, increased wear of the side surfaces of rail heads, decrease in the coefficient of stability of wagons from derailment, etc. To test this hypothesis, a study was conducted to obtain dependencies, first of all, these are the characteristics of the influence of geometric deviations of the position of the wheel pairs in the cart on the level of guiding forces in the contacts of the wheels with the rails and the wear of the wheel flanges. The relevance of this study is confirmed by data on the catastrophic wear of rails and solid-rolled wheels of wagons. An analysis of statistical data oblique setting of wheel pairs in carts in plan due to running-in of side frames was made, which shows that in 80% of wagons these angles can be up to 0,015 rad (0,85 degrees). The formula for the critical derailment ratio of the frame force to the vertical load on the wheel has been clarified, in contrast to Nadal's formula, which additionally takes into account the deflection forces in the contact of the overlapping wheel.
Conference papers on the topic "Freight cars Wheels"
1
Huang, Wei, and Yan Liu. "Unsafe Hunting of Freight Rail Cars." In 2009 Joint Rail Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/jrc2009-63042.
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Hunting of rail vehicles refers to self-excited oscillation of truck and carbody. This dynamic instability is due to the conicity of the wheels, the wheel/rail creep forces and the action of the suspensions. Hunting increases wheel/rail wear, causes damage to sensitive lading and in extreme cases can throw the track out of geometry. Furthermore, severe hunting can create unsafe operating conditions that lead to derailments. Although it is widely recognized that truck hunting is not a good thing, it is a fact that many thousands of trucks do hunt on any given day but the number of derailments from hunting are few. So when is the hunting unsafe? Database and parametric studies of unsafe hunting are presented in this paper. The FRA database was used to study the hunting derailments by year, car type, track, speed, load condition, weather and temperature. Parametric studies of hunting and unsafe hunting of three-piece freight cars were conducted based on a large number of measured wheel profiles in combination with worn and new rail profiles. The vehicle, track and operational factors that have the major influence on unsafe hunting are analyzed and the conditions of unsafe hunting presented.
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Nagode, C., M. Ahmadian, and S. Taheri. "Axle Generator for Freight Car Electric Systems." In 2012 Joint Rail Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/jrc2012-74069.
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As the desire to implement more electronic devices such as measuring or tracking systems on freight cars grows, having a source of power to rely on becomes an issue. An innovative and practical solution to keep batteries charged is presented. Placed on the car axle, the system uses the rotation of the wheelset as input motion. Friction wheels roll on the outside of the car axle, transferring the power to a generator through a set of gears. Designed to be easily implemented, the system can be installed or removed conveniently and quickly. The first laboratory tests showed that the system is capable of producing more than 100 Watts of power at a simulated 55 mph. A speed of only 20 mph is necessary to generate voltages high enough to charge a 12-Volt battery. A second series of tests proves that connecting the generator differently (in a “Y” configuration) improves the output voltages by about 70%, generating three times more power and requiring only 10mph to reach the voltage necessary for charging a common lead-acid battery.
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Cummings, Scott M., and Don Lauro. "Inspections of Tread Damaged Wheelsets." In ASME 2008 Rail Transportation Division Fall Technical Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/rtdf2008-74009.
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Inspections of 163 wheelsets conducted by the Wheel Defect Prevention Research Consortium (WDPRC) have produced critical information in identifying the high-level root causes of tread damage. While the overall wheel tread damage problem appears to be split fairly evenly between shelling and spalling, the type of tread damage on a wheelset is strongly linked to the type of car from which it was removed. Coal car wheels, which generally run in heavy axle load, high-mileage service with minimal yard handling, are almost exclusively subject to shelling damage with little spalling damage. On the other hand, mixed freight cars, such as tank cars and covered hopper cars, tend to run in lower mileage service with more yard handling, resulting in fewer loading cycles under lighter stress and more frequent use of hand brakes. Not surprisingly then, wheels from these types of cars were observed to have a mix of spalling and shelling damage, with spalling being the predominant damage mechanism. Nearly every high impact wheel (HIW) inspected showed either spalling, shelling, or some combination of the two. As expected, wheel impact load detector (WILD) readings and radial tread run out data were found to be related. Rim thickness deviations and rim lateral face deviations were not found to be important contributors to shelling. The lateral tread location of radial run-out deviations and crack bands could be an important clue in discovering the root cause of shelling. Radial run-out data and crack band location data shows that shelling damage is most prevalent outboard of the tapeline. This is the expected wheel/rail contact position of a wheel in the lead wheelset position of a truck, while riding on the low (inside) rail of a curve. Many of the wheels that were removed for wear causes were found to have noncondemnable shelling and spalling, indicating that tread damage is more prevalent than repair records would indicate.
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Lonsdale, Cameron, and Steven Dedmon. "Fatigue Testing of Microalloyed AAR Class C Wheel Steel." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13366.
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Railroad wheels guide a freight car along the rails while supporting mechanical loads, and also serve as the brake drum in the air brake system of a freight car. Since a 36-inch diameter freight car wheel experiences approximately 560 revolutions per mile, and since many North American freight cars accrue 100,000 miles per year in service, fatigue properties of steel are very important. Further, elevated tread temperatures resulting from tread braking are known to significantly reduce the yield strength of the wheel steel at the tread surface. This paper describes fatigue testing of AAR rim quenched Class C wheel steel manufactured with microalloy additions. Small amounts of selected alloy elements were purposely added to develop a wheel steel with improved high temperature yield strength. Rotating bending fatigue tests, conducted at a well-known professional testing laboratory, were performed at ambient and elevated temperatures using complete stress reversal (R = -1) cycling. Stress-life (S-N) curves were constructed and the microalloy steel results were compared to existing fatigue data, and to results for typical Class C steel with no microalloy additions. Past research work is briefly reviewed. Test results are discussed with emphasis on the implications for service performance of wheel steel.
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Cummings, Scott. "Brake Shoe Force Variation." In ASME 2009 Rail Transportation Division Fall Technical Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/rtdf2009-18021.
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The Wheel Defect Prevention Research Consortium (WDPRC) has conducted a review and analysis of existing literature and existing data related to brake shoe force (BSF) variation in freight car brake rigging. This work was conducted to explore the sources of BSF variation, define the expected amount of BSF variation, and describe some of the existing brake system designs that may help reduce the amount of BSF variation. Wheel temperature is related to BSF due to the use of the wheel tread as a brake drum. Variation in BSF within a given railcar is one potential source of elevated wheel temperatures and thermal mechanical shelling (TMS) damage to the wheels. At elevated temperatures, wheels become less resistant to fatigue damage due to changes in the material mechanical properties and relief of beneficial residual stresses. Data recorded by a wayside wheel temperature detector shows that eliminating wheel temperature differences within individual cars could reduce the number of wheels reaching temperatures of concern for TMS by a factor of eight.
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Santos, A. A., S. J. Romano, and F. C. Santos. "Theoretical and Experimental Comparison of the Heating From Shoe-Wheel and Pad-Disk Braking Systems for Railroad Freight Cars." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68684.
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Brazilian freight cars use brake shoes directly applied onto the wheels. This system causes wheel heating, which in turn gives rise to thermal stresses and loss of mechanical strength. An alternate solution is a system of brake disks and pads, which would not heat the wheels. This system is not used in high load railroads. Because temperature is one of the major factors affecting braking performance, a study of the viability of replacing shoe brakes by disk brakes must evaluate and compare the heating of wheels and disks. The present work evaluates the heating of disk-pad systems when used for braking freight cars. Preliminary numerical simulations were done to check whether the expected temperatures would exceed the limits and damage friction materials and systems. Following that, real scale tests were conducted in critical braking conditions for both types of brake systems. Dynamometer tests were performed in real scale at the Railroad Laboratory of the State University of Campinas, Brazil. Results showed that, as far as system heating is concerned, there is nothing to prevent the replacement of the current system by a disk-pad system.
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Watts, Travis J., Jerry G. Rose, and Ethan J. Russell. "Relationships Between Wheel/Rail Surface Impact Loadings and Correspondingly Transmitted Tie/Ballast Impact Pressures for Revenue Train Operations." In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6184.
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A series of specially designed granular material pressure cells were precisely positioned directly below the rail at the tie/ballast interface to measure typical interfacial pressures exerted by revenue freight trains. These vertical pressures were compared to the recorded wheel/rail nominal and peak forces for the same trains traversing nearby mainline wheel impact load detectors (WILDs). The cells were imbedded within the bottom of new wood ties so that the surfaces of the pressure cells were even with the bottoms of the ties and the underlying ballast. The cells were inserted below consecutive rail seats of one rail to record pressures for a complete wheel rotation. The stability and tightness of the ballast support influenced the magnitudes and consistencies of the recorded ballast pressures. Considerable effort was required to provide consistent ballast conditions for the instrumented ties and adjacent undisturbed transition ties. Norfolk Southern (NS) crews surfaced and tamped through the test section and adjacent approach ties. This effort along with normal accruing train traffic subsequently resulted in reasonably consistent pressure measurements throughout the test section. The impact ratio (impact factor) and peak force values recorded by the WILDs compared favorably with the resulting magnitudes of the transferred pressures at the tie/ballast interface. High peak force and high impact ratio WILD readings indicate the presence of wheel imperfections that increase nominal forces at the rail/wheel interface. The resulting increased dynamic impact forces can contribute to higher degradation rates for the track component materials and more rapid degradation rates of the track geometry. The paper contains comparative WILD force measurements and tie/ballast interfacial pressure measurements for loaded and empty trains. Typical tie/ballast pressures for locomotives and loaded freight cars ranges from 20 to 30 psi (140 to 210 kPa) for smooth wheels producing negligible impacts. The effect of increased wheel/rail impacts and peak force values on the correspondingly transmitted pressures at the tie/ballast interface is significant, with increased pressures of several orders of magnitude compared to nominal impact forces from wheels.
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Kirkpatrick, Steven W. "An Evaluation of Derailment Mechanics and Derailment Analysis Methodologies." In 2021 Joint Rail Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/jrc2021-58527.
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Abstract Detailed analyses of vehicle and train collisions are a common part of new vehicle design projects. It is relatively simple to describe appropriate collision scenarios for a train and the resulting collision mechanics are reasonably controlled if the trains remain upright and in-line. These scenarios are well suited to advanced dynamic finite element simulation codes. Alternatively, train derailment analyses are less common and have unique characteristics that make the analyses difficult. The derailment event can involve the interaction of many cars and have a relatively long duration compared to other crash events. Freight derailments can involve trains in excess of 100 cars long and the duration of the derailment response can be on the order of a minute before coming to rest. Further complicating the analysis are the many parameters that are not well characterized or controlled. The motions of rail cars after leaving the tracks are not well known and difficult to model. The wheels and trucks can plough through ground or remaining track sections. The material properties and geometry of the ground can have large variations and are typically not well known or characterized for specific derailment events. Additionally, the geometry of the surrounding terrain can have a wide range of variability at derailment sites. As a result of these complexities, there are far fewer standardized methodologies used for the analysis of derailments. The detailed finite element models are applied in some cases, but the computational requirements to model these events in high fidelity are quite high. This paper provides a review of some past derailment modeling efforts and recent investigations and analyses of derailment events to provide insights into the derailment mechanics of freight trains. The objective is to assess the relative magnitudes of effects such as the braking characteristics, brake application delay time, and blockage force caused by the derailed and overturned cars on the subsequent deceleration of the trailing cars on the rail.
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Stewart, Monique F., Som P. Singh, David R. Andersen, Rou Wen, and Graydon F. Booth. "Wheel Temperature Reduction During Freight Car Braking." In 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5819.
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Since the adoption of 286,000 lb gross rail load (286K GRL) car service, an increase in wheel thermal damage and shelling has been observed. This is attributed to the increased braking horsepower in 286K GRL service as compared to the 263K GRL service environment. This study investigated possible designs and methods of braking that could lead to reduced heat input to the tread of freight car wheels in order to mitigate this damage and reduce its occurrence to a level closer to that seen with 263K GRL car service. Fifteen potential concepts to lower the thermal input to wheels and/or accelerate heat removal from the tread were identified and evaluated using the following engineering categories: simplicity of design, maintenance requirements, weight considerations, material and manufacturing costs, controllability of braking effort, and market acceptability. Five final concepts — axle-mounted disc, cheek disc, wheel rim, axle-mounted drum, and high convection coating — were developed through preliminary design and thermal analysis to confirm their effectiveness in meeting the objectives. Four concepts for alternative braking methods — axle-mounted disc brakes, cheek disc brakes, wheel rim clasp brakes, and axle-mounted drum brakes — were analyzed in considerable detail. Of the four concepts presented, the first three appear to be feasible and would be potential candidates for further detailed investigations/evaluation. It is shown that as the demand on railway wheels to withstand increased mechanical and thermal loads grows, there are viable braking enhancements that can help manage the stress state in freight car wheels.
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Liu, Qingjie, Xiaoyan Lei, Jerry G. Rose, and Macy L. Purcell. "Pressure Measurements at the Tie-Ballast Interface in Railroad Tracks Using Granular Material Pressure Cells." In 2017 Joint Rail Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/jrc2017-2219.
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It has been desirable for years to develop a reasonably simple, direct, accurate, and reliable method to measure pressure distributions in railroad trackbeds, especially the pressure magnitudes and distributions at the tie-ballast interface. In this study, specially-designed granular material pressure cells were used to measure pressure magnitudes and distributions. The cells were placed directly under the rail-tie intersection at the tie-ballast interface. Initially, a MTS test machine was used to conduct a series of laboratory tie-ballast box tests for a wide variation of ballast types and loading configurations. The adequacy of the cells for in-track measurements was verified with a series of very controlled laboratory tests and measurements using simulated trackbed sections and loading conditions. Excellent correlations were obtained comparing applied machine pressures and measured transferred cell pressures indicating that this type of pressure cell is suitable for in-track tie-ballast pressure measurements. This preliminary testing sequence is briefly described. A series of in-track wood tie tests were conducted on a yard lead track on a shortline railroad, Transkentucky Transportation, to optimize the in-track installation procedures and to obtain pressure measurements using repeated passes of low-speed locomotives and cars. A normalized pressure distribution was obtained by using metal shims when necessary to fill voids between the ties and pressure cells to insure continuous tie-ballast contact. This test sequence is presented and described. Additional in-track tests were conducted on Norfolk Southern Railway’s heavy tonnage concrete tie Class 4 mainline with train speeds of up to 64 km/h. Data was obtained for numerous passages of revenue trains over a period of several months for variable weights and types of locomotives and freight cars at typical train speeds. The average pressure intensities at the tie-ballast interface were acquired for six consecutive ties comprising a complete revolution of the wheels. This data is presented and the results discussed.