In different cases in industry such as bearings, rollers and wheel/rail, there are different criteria for predicting the life of the components, being worn. One criterion for determining wear amount in wheel and rail is based on frictional work, to which the removed material is proportional in the contact patch, and is available as an output in ADAMS/RAIL/spl copy/ software. In this paper, an approach is introduced to determine the function which converts wear number to wear rate. So after simulation of a line, either before or after construction, the wear rate can be obtained from the wear number which was obtained from simulation. Therefore, it will be possible to discover whether the wear condition will be satisfactory or not for a line which is not constructed yet. To test the second line, the Tehran subway was selected and fleet and track of that line was modeled in ADAMS/RAIL/spl copy/.
{"title":"Determination of the wear criterion","authors":"I. Ashtiyani, M. Ansari","doi":"10.1115/JRC2006-94028","DOIUrl":"https://doi.org/10.1115/JRC2006-94028","url":null,"abstract":"In different cases in industry such as bearings, rollers and wheel/rail, there are different criteria for predicting the life of the components, being worn. One criterion for determining wear amount in wheel and rail is based on frictional work, to which the removed material is proportional in the contact patch, and is available as an output in ADAMS/RAIL/spl copy/ software. In this paper, an approach is introduced to determine the function which converts wear number to wear rate. So after simulation of a line, either before or after construction, the wear rate can be obtained from the wear number which was obtained from simulation. Therefore, it will be possible to discover whether the wear condition will be satisfactory or not for a line which is not constructed yet. To test the second line, the Tehran subway was selected and fleet and track of that line was modeled in ADAMS/RAIL/spl copy/.","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121622729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In 2001, a comprehensive test program was conducted under the AAR strategic research initiatives program by the Transportation Technology Center, Inc. (TTCI), Pueblo, Colorado, to determine the best types of constant contact side bearings (CCSBs) for use in 10 different North American freight cars. Test results indicated that long travel (LT) CCSB designs generally provided the best overall performance, which lead to an industry wide rule change. By using LT-CCSB, rail operations can be improved by maintaining better vertical wheel loads, providing high-speed stability, and providing more predictable truck turning forces. With a better understanding of both CCSB performance and the needs of the rail industry, an updated specification M-948 (AAR's Manual of Standards and Recommended Practices) was researched and revised in 2005. This paper documents the evolution of LT-CCSB research and the industry's implementation efforts since testing began in 2001. The testing and modeling that was performed in 2001 concentrated on car types that had a history of unpredictable performance. Well-maintained cars were selected to highlight the characteristics of long, short, tall, and torsional stiffness that each plays a part in the vehicles ability to reliably negotiate the railroad. Of the 10 cars, four were both track tested and modeled and the balance were only modeled. In almost every case, the railcars had a demonstrable performance improvement with the simple application of LT-CCSBs. The AAR quickly reacted by requiring all new cars and cars meeting certain conditions to have LT-CCSB (Rule 88). Following this test program two other independent tests were conducted, which demonstrated the advantages of LT-CCSBs. The first was a rail service test of two diesel tank cars and the second was a series of controlled tests on a tank car that had derailed at high speed. In both cases performance was markedly improved by the application of LT-CCSB. Finally the industry needed to update the side bearing specification M-948, in order to reliably control the performance of LT-CCSBs and preserve the benefit derived from their use. In preparation, a 2-year rail service test was conducted on three different cars, which were a refrigerated orange juice boxcar (operated in high speed intermodal or "Ztrain" service), an intermodal car, and a coal gondola. Using the data from these cars and knowledge from participants in the CCSB supply industry, the M-948 specification was revised to represent and preserve the operational benefits derived from CCSBs. This paper also documented an audit of the specification to highlight advantages from the revised M-948 specification.
{"title":"Understanding the benefits of long travel constant contact side bearings","authors":"D. Iler","doi":"10.1115/JRC2006-94050","DOIUrl":"https://doi.org/10.1115/JRC2006-94050","url":null,"abstract":"In 2001, a comprehensive test program was conducted under the AAR strategic research initiatives program by the Transportation Technology Center, Inc. (TTCI), Pueblo, Colorado, to determine the best types of constant contact side bearings (CCSBs) for use in 10 different North American freight cars. Test results indicated that long travel (LT) CCSB designs generally provided the best overall performance, which lead to an industry wide rule change. By using LT-CCSB, rail operations can be improved by maintaining better vertical wheel loads, providing high-speed stability, and providing more predictable truck turning forces. With a better understanding of both CCSB performance and the needs of the rail industry, an updated specification M-948 (AAR's Manual of Standards and Recommended Practices) was researched and revised in 2005. This paper documents the evolution of LT-CCSB research and the industry's implementation efforts since testing began in 2001. The testing and modeling that was performed in 2001 concentrated on car types that had a history of unpredictable performance. Well-maintained cars were selected to highlight the characteristics of long, short, tall, and torsional stiffness that each plays a part in the vehicles ability to reliably negotiate the railroad. Of the 10 cars, four were both track tested and modeled and the balance were only modeled. In almost every case, the railcars had a demonstrable performance improvement with the simple application of LT-CCSBs. The AAR quickly reacted by requiring all new cars and cars meeting certain conditions to have LT-CCSB (Rule 88). Following this test program two other independent tests were conducted, which demonstrated the advantages of LT-CCSBs. The first was a rail service test of two diesel tank cars and the second was a series of controlled tests on a tank car that had derailed at high speed. In both cases performance was markedly improved by the application of LT-CCSB. Finally the industry needed to update the side bearing specification M-948, in order to reliably control the performance of LT-CCSBs and preserve the benefit derived from their use. In preparation, a 2-year rail service test was conducted on three different cars, which were a refrigerated orange juice boxcar (operated in high speed intermodal or \"Ztrain\" service), an intermodal car, and a coal gondola. Using the data from these cars and knowledge from participants in the CCSB supply industry, the M-948 specification was revised to represent and preserve the operational benefits derived from CCSBs. This paper also documented an audit of the specification to highlight advantages from the revised M-948 specification.","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126430634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Railroad turnouts are discontinuities in the track structure that are needed to move a rail vehicle from one track to another. These discontinuities generate high dynamic forces, to include high lateral forces into and through the switch, due to abrupt or non-uniform changes in track geometry. In the diverging route, these discontinuities frequently create a need for speed restrictions. While there have been many attempts at improving turnout design, and in particular switch designs, most new designs (such as tangential geometry points) are generally incompatible with conventional (AREMA) designs and usually require additional length of track, which is often not available. Recent research has examined new switch designs, which offer reduced dynamic loading, while maintaining the existing turnout length, particularly the switch lead length, thus avoiding moving or replacing the frog, a considerable expense. One recent set of designs looks at a new switch geometry that offered significant reductions in lateral dynamic forces, as well as the potential for high speed through the switch. Successful model simulations, led to the fabrication of two prototype switches and their installation on New Jersey Transit. Subsequent field tests verified the reduction in dynamic forces and showed significant potential for reduced vehicle dynamics. On board acceleration measurements confirmed this improved dynamic behavior. This paper presents the conceptual development, modeling, simulation and testing to include comparative simulation and testing of alternate switch designs focusing on improved vehicle dynamics through the switch.
{"title":"Optimizing vehicle dynamics through a switch while maintaining existing switch lead length","authors":"C. S. Bonaventura, D. Holfeld, A. Zarembski","doi":"10.1115/JRC2006-94013","DOIUrl":"https://doi.org/10.1115/JRC2006-94013","url":null,"abstract":"Railroad turnouts are discontinuities in the track structure that are needed to move a rail vehicle from one track to another. These discontinuities generate high dynamic forces, to include high lateral forces into and through the switch, due to abrupt or non-uniform changes in track geometry. In the diverging route, these discontinuities frequently create a need for speed restrictions. While there have been many attempts at improving turnout design, and in particular switch designs, most new designs (such as tangential geometry points) are generally incompatible with conventional (AREMA) designs and usually require additional length of track, which is often not available. Recent research has examined new switch designs, which offer reduced dynamic loading, while maintaining the existing turnout length, particularly the switch lead length, thus avoiding moving or replacing the frog, a considerable expense. One recent set of designs looks at a new switch geometry that offered significant reductions in lateral dynamic forces, as well as the potential for high speed through the switch. Successful model simulations, led to the fabrication of two prototype switches and their installation on New Jersey Transit. Subsequent field tests verified the reduction in dynamic forces and showed significant potential for reduced vehicle dynamics. On board acceleration measurements confirmed this improved dynamic behavior. This paper presents the conceptual development, modeling, simulation and testing to include comparative simulation and testing of alternate switch designs focusing on improved vehicle dynamics through the switch.","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120962326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There are a number of theoretical and practical techniques to compute rail vehicle wheel wear. For instance, the Archard equation is a well-known tool to determine the worn volume in sliding contact, although it was established for normal loads, sliding distance and the surface hardness. Of course the wear coefficient (called K) used in this equation to differentiate the wear modes, implicitly comprises the conditions that govern the contact surface. Two situations can be taken into account when considering a sliding contact, particularly along a curved track: i) when the radial force prevails the lateral tangential force, which is mainly the frictional force but before flanging and ii) during flange contact. Also, the Archard equation is employed within the tread and flange regions separately, both the regions being of interest in this paper. A number of approaches are then used to find the distance slid. The author compares the field test results and the outcome of the analytical approaches. The wheel wear results acquired from the two test bogies on Iranian Railways when all technical (rigid frame bogies with new assemblies and components) and operational items were identical, except for changing the bogie orientation in the second test trial for a short period. Good agreement was found between the analytical and practical investigations
{"title":"Wheel wear prediction - comparison between analytical approaches and field tests","authors":"A. Lari","doi":"10.1115/JRC2006-94054","DOIUrl":"https://doi.org/10.1115/JRC2006-94054","url":null,"abstract":"There are a number of theoretical and practical techniques to compute rail vehicle wheel wear. For instance, the Archard equation is a well-known tool to determine the worn volume in sliding contact, although it was established for normal loads, sliding distance and the surface hardness. Of course the wear coefficient (called K) used in this equation to differentiate the wear modes, implicitly comprises the conditions that govern the contact surface. Two situations can be taken into account when considering a sliding contact, particularly along a curved track: i) when the radial force prevails the lateral tangential force, which is mainly the frictional force but before flanging and ii) during flange contact. Also, the Archard equation is employed within the tread and flange regions separately, both the regions being of interest in this paper. A number of approaches are then used to find the distance slid. The author compares the field test results and the outcome of the analytical approaches. The wheel wear results acquired from the two test bogies on Iranian Railways when all technical (rigid frame bogies with new assemblies and components) and operational items were identical, except for changing the bogie orientation in the second test trial for a short period. Good agreement was found between the analytical and practical investigations","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127862995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crashworthiness strategies, which include crash energy management (CEM), pushback couplers, and push/pull operation, are evaluated and compared under specific collision conditions. Comparisons of three strategies are evaluated in this paper: push versus pull operation (cab car led versus locomotive led consists); conventional versus CEM consists; and incremental CEM versus full-CEM. Rail cars that incorporate CEM are designed to absorb collision energy through crushing of unoccupied structures within the car. Pushback couplers are designed to recede into the draft sill under collision loads and enable the car ends to come into contact, minimizing the likelihood of lateral buckling. Push/pull operation refers to operating either a locomotive (pull mode) or a cab car (push mode) at the leading end of the train. Five cases using combinations of these three strategies are evaluated. The basic collision scenario for each case analyzed in this paper is a train-to-train collision between like trains. Each train has a locomotive, four coach cars, and a cab car. The impact velocity ranges from 10 to 40 mph. The following five cases are evaluated: (1) all conventional cars with a cab car leading (baseline case); (2) all conventional cars with a locomotive leading; (3) conventional coach cars with pushback couplers, with CEM cab car leading; (4) all CEM cars with a cab car leading: (5) all CEM cars with a locomotive leading. A one-dimensional lumped-mass collision dynamics model is used to evaluate the effectiveness of each strategy, or combination of strategies, in terms of preserving survivable space for occupants and minimizing secondary impact velocity (SIV). Test data is used to correlate SIV with head, chest, and neck injury. Probability of serious injuries and fatalities are calculated based on calculated car crush and injury values. The maximum crashworthy speed, or the maximum impact speed at which everyone is expected to survive, is calculated for each case. Of the five cases evaluated, the scenario of a cab car led conventional consist represents the baseline level of crashworthiness. The highest levels of crashworthiness are achieved by a consist of all CEM cars with a locomotive leading, followed by all CEM cars with a cab car leading. The results indicate that incremental improvements in collision safety can be made by judiciously applying different combinations of these crashworthiness strategies. A CEM cab car leading conventional cars that are modified with pushback couplers enhances the level of crashworthiness over a conventional cab car led consist and provides a level of crashworthiness equal to a locomotive leading conventional passenger cars
{"title":"Effectiveness of alternative rail passenger equipment crashworthiness strategies","authors":"K. Jacobsen, K. Severson, B. Perlman","doi":"10.1115/JRC2006-94043","DOIUrl":"https://doi.org/10.1115/JRC2006-94043","url":null,"abstract":"Crashworthiness strategies, which include crash energy management (CEM), pushback couplers, and push/pull operation, are evaluated and compared under specific collision conditions. Comparisons of three strategies are evaluated in this paper: push versus pull operation (cab car led versus locomotive led consists); conventional versus CEM consists; and incremental CEM versus full-CEM. Rail cars that incorporate CEM are designed to absorb collision energy through crushing of unoccupied structures within the car. Pushback couplers are designed to recede into the draft sill under collision loads and enable the car ends to come into contact, minimizing the likelihood of lateral buckling. Push/pull operation refers to operating either a locomotive (pull mode) or a cab car (push mode) at the leading end of the train. Five cases using combinations of these three strategies are evaluated. The basic collision scenario for each case analyzed in this paper is a train-to-train collision between like trains. Each train has a locomotive, four coach cars, and a cab car. The impact velocity ranges from 10 to 40 mph. The following five cases are evaluated: (1) all conventional cars with a cab car leading (baseline case); (2) all conventional cars with a locomotive leading; (3) conventional coach cars with pushback couplers, with CEM cab car leading; (4) all CEM cars with a cab car leading: (5) all CEM cars with a locomotive leading. A one-dimensional lumped-mass collision dynamics model is used to evaluate the effectiveness of each strategy, or combination of strategies, in terms of preserving survivable space for occupants and minimizing secondary impact velocity (SIV). Test data is used to correlate SIV with head, chest, and neck injury. Probability of serious injuries and fatalities are calculated based on calculated car crush and injury values. The maximum crashworthy speed, or the maximum impact speed at which everyone is expected to survive, is calculated for each case. Of the five cases evaluated, the scenario of a cab car led conventional consist represents the baseline level of crashworthiness. The highest levels of crashworthiness are achieved by a consist of all CEM cars with a locomotive leading, followed by all CEM cars with a cab car leading. The results indicate that incremental improvements in collision safety can be made by judiciously applying different combinations of these crashworthiness strategies. A CEM cab car leading conventional cars that are modified with pushback couplers enhances the level of crashworthiness over a conventional cab car led consist and provides a level of crashworthiness equal to a locomotive leading conventional passenger cars","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132812817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-04DOI: 10.1109/RRCON.2006.215315
S. Nikouee, T. Ledbetter
The best place to see all aspects of a heavy rail transit traction power supply and distribution system in action is at a storage and maintenance Yard located adjacent to the main line. This paper presents an overview of the DC traction power system (TPS) for Metropolitan Atlanta Rapid Transit Authority's Armour Yard Rail Services Facility. This state-of-the-art facility is constructed for MARTA's newly increased fleet size to accommodate rail car storage, train wash, interior car cleaning, service, inspection, maintenance, and component overhaul
{"title":"DC traction power supply and distribution system for MARTA's Armour Yard Rail Services Facility","authors":"S. Nikouee, T. Ledbetter","doi":"10.1109/RRCON.2006.215315","DOIUrl":"https://doi.org/10.1109/RRCON.2006.215315","url":null,"abstract":"The best place to see all aspects of a heavy rail transit traction power supply and distribution system in action is at a storage and maintenance Yard located adjacent to the main line. This paper presents an overview of the DC traction power system (TPS) for Metropolitan Atlanta Rapid Transit Authority's Armour Yard Rail Services Facility. This state-of-the-art facility is constructed for MARTA's newly increased fleet size to accommodate rail car storage, train wash, interior car cleaning, service, inspection, maintenance, and component overhaul","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129103348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-04DOI: 10.1109/RRCON.2006.215310
S. E. Brister, E. Dahlman, N.J. Stecyk
This paper reviews several areas of focus for improving axle reliability in North American Freight Car Service. These include many different methods of achieving improvements including exploration of enhanced axle materials and revision of current material requirements to improve the fatigue strength of axles. A second method discussed is the strengthening of requirements for repairing axle fillet damage to improve safety in operation of second hand axles. The final area discussed in this paper is prevention of axle journal fillet damage through the utilization of corrosion preventative coatings and requiring fitted journal bearing applications
{"title":"Improving axle reliability in North American Freight Service","authors":"S. E. Brister, E. Dahlman, N.J. Stecyk","doi":"10.1109/RRCON.2006.215310","DOIUrl":"https://doi.org/10.1109/RRCON.2006.215310","url":null,"abstract":"This paper reviews several areas of focus for improving axle reliability in North American Freight Car Service. These include many different methods of achieving improvements including exploration of enhanced axle materials and revision of current material requirements to improve the fatigue strength of axles. A second method discussed is the strengthening of requirements for repairing axle fillet damage to improve safety in operation of second hand axles. The final area discussed in this paper is prevention of axle journal fillet damage through the utilization of corrosion preventative coatings and requiring fitted journal bearing applications","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131456100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-04DOI: 10.1109/RRCON.2006.215294
G. Booth, A. Prabhakaran, S. Punwani, M. Stewart
A method is presented for predicting brake shoe force of a rail vehicle as a linear function of effective brake cylinder pressure. Historically, the braking force has been calculated as the product of cylinder pressure, cylinder area, rigging leverage ratio, and an overall system efficiency factor. The efficiency factor, which takes into account frictional forces and other losses, is a non-linear function of brake cylinder pressure. The method presented here uses a modified formulation for braking force that does not require a non-linear representation of efficiency. Instead, the braking force is represented as a linear function of effective (or net) cylinder pressure. Effective cylinder pressure is the actual cylinder pressure reduced by the initial cylinder pressure required to set the brake shoes against the wheels with no net force transmitted to the wheels. This method of determining the braking force allows a clearer understanding of the role of rigging efficiency, breaking it into fixed losses (such as return spring force) and purely frictional losses that are directly proportional to load (such as pin friction). This approach for calculating brake shoe force as a function of effective cylinder pressure has several advantages over the conventional method (as described above) using nonlinear rigging efficiency: the mathematical formulation is a more appropriate representation of the pertinent physical aspects of the brake cylinder and rigging; complex curve-fit representations of efficiency for different rigging types are avoided; shoe force as a function of cylinder pressure is characterized (for a given vehicle) by just two parameters, each of which has a clear physical meaning and may be readily determined for any particular car using common brake system measurement techniques. Published discussions of efficiency and its approximation to measured data for various types of car rigging are compared with predictions from the subject method and show close correlation
{"title":"Simplified representation of rigging efficiency in brake force calculation","authors":"G. Booth, A. Prabhakaran, S. Punwani, M. Stewart","doi":"10.1109/RRCON.2006.215294","DOIUrl":"https://doi.org/10.1109/RRCON.2006.215294","url":null,"abstract":"A method is presented for predicting brake shoe force of a rail vehicle as a linear function of effective brake cylinder pressure. Historically, the braking force has been calculated as the product of cylinder pressure, cylinder area, rigging leverage ratio, and an overall system efficiency factor. The efficiency factor, which takes into account frictional forces and other losses, is a non-linear function of brake cylinder pressure. The method presented here uses a modified formulation for braking force that does not require a non-linear representation of efficiency. Instead, the braking force is represented as a linear function of effective (or net) cylinder pressure. Effective cylinder pressure is the actual cylinder pressure reduced by the initial cylinder pressure required to set the brake shoes against the wheels with no net force transmitted to the wheels. This method of determining the braking force allows a clearer understanding of the role of rigging efficiency, breaking it into fixed losses (such as return spring force) and purely frictional losses that are directly proportional to load (such as pin friction). This approach for calculating brake shoe force as a function of effective cylinder pressure has several advantages over the conventional method (as described above) using nonlinear rigging efficiency: the mathematical formulation is a more appropriate representation of the pertinent physical aspects of the brake cylinder and rigging; complex curve-fit representations of efficiency for different rigging types are avoided; shoe force as a function of cylinder pressure is characterized (for a given vehicle) by just two parameters, each of which has a clear physical meaning and may be readily determined for any particular car using common brake system measurement techniques. Published discussions of efficiency and its approximation to measured data for various types of car rigging are compared with predictions from the subject method and show close correlation","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114614191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the dynamic characteristics of traction load and unevenly train dispatch schedule, the unbalances currents are generally presented at point of common coupling (PCC). To suppress the degree of unbalance, a specially connected transformer or/and reactive power compensation device can be applied. Traditionally, a phase-shifted Scott transformer type SVC was installed in front of Scott connection transformer to improve the voltage fluctuation which is caused by high speed railway (HSR) systems. However, this solution is the most effective only in case that the power factor angle of each phase load equals pi/6 lagging; otherwise, a quite severe negative sequence current still presented at PCC. In this investigation, a new hybrid SVC scheme is proposed to improve this disadvantage. The results show that the proposed scheme can effectively restrict the negative sequence current to zero no matter what power factor of traction load
{"title":"A new hybrid SVC scheme with Scott transformer for balance improvement","authors":"Wen-Shyan Chu, J. Gu","doi":"10.1115/JRC2006-94005","DOIUrl":"https://doi.org/10.1115/JRC2006-94005","url":null,"abstract":"Due to the dynamic characteristics of traction load and unevenly train dispatch schedule, the unbalances currents are generally presented at point of common coupling (PCC). To suppress the degree of unbalance, a specially connected transformer or/and reactive power compensation device can be applied. Traditionally, a phase-shifted Scott transformer type SVC was installed in front of Scott connection transformer to improve the voltage fluctuation which is caused by high speed railway (HSR) systems. However, this solution is the most effective only in case that the power factor angle of each phase load equals pi/6 lagging; otherwise, a quite severe negative sequence current still presented at PCC. In this investigation, a new hybrid SVC scheme is proposed to improve this disadvantage. The results show that the proposed scheme can effectively restrict the negative sequence current to zero no matter what power factor of traction load","PeriodicalId":292357,"journal":{"name":"Proceedings of the 2006 IEEE/ASME Joint Rail Conference","volume":"159 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123078807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-04DOI: 10.1109/RRCON.2006.215307
H. Harrison, Li Cheng, W. GeMeiner
The railroad industry is committed to cost effectively reduce the stress state of its infrastructure. As market forces drive up the gross weight on rail, it becomes more necessary to truncate the undesirable upper tail of the load distribution that overlaps the lower tail of the infrastructure strength distribution. One way to achieve this is to cost-effectively weigh the rolling stock and flag the poorly loaded and/or overloaded cars. This paper describes a system that fulfills this goal. When custody transfer terms require, vehicles are weighed in the hump yard or, in the case of bulk commodities, at the point of origin. The former method is not cost or time effective and neither approach detects the weight distribution in the vehicle. Furthermore, only a small percentage of traffic is routed through the classification yards. The authors have contributed to the development of a high-speed, weigh-in-motion system (HS/WIM) that resolves these difficulties by providing railroads with a low cost means of screening the state of the traffic crossing their territory. This paper describes both the working theory behind the system design and the economic benefits gained by monitoring car load distribution dynamically at operational train speeds. Finally, this paper discusses other related issues and potential future improvements of the current system
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