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Keywords: rolling stock design, modelling, simulation, long trains, in-train forces, heavy haul.

Summary

Vale S.A is the largest mining and railroad company in Brazil. Vale intends to increase axle loads from 31.5 tonne, to 32.5 tonne, and eventually to 37.5 tonne on its 900 km railroad in northern Brazil, named Estrada de Ferro Carajás (EFC). Existing wagons (GDT) are being upgraded from 31.5 to 32.5 tonne axle load capacity. New GDU wagons are being procured to operate at 37.5 tonne axle loads.

Mathematical modelling was conducted to evaluate the in-train forces using TOES^TM and NUCARS® software at 31.5, 32.5 and 37.5 tonne axle loads. The most critical section was selected for this analysis. The section includes a sag, where a loaded train must negotiate a 0.96 percent decent followed by a 0.36 percent ascent.

The Association of American Railroads (AAR) design requirements for freight wagons to be used in unit train operations [1] specify that the wagon structure be designed for 1,557 kN (350 kips) buff and 2,224 kN (500 kips) draft and be able to withstand 4,448 kN (1,000 kips) compressive load. For GDT wagons, limits of 1,557 kN (350 kips) buff and draft forces are proposed based on AAR wagon design limits. Predicted forces are well below these limits. The risk of jack-knifing and string lining is minimal at the predicted forces. Fatigue performance of couplers is currently being investigated. For GDU wagons the risk of flange climb derailment and rail roll over are acceptable. The risk of track panel shift is acceptable on curves with well-maintained spirals but not acceptable on curves without well-maintained spirals under high buff conditions.

The predicted draft forces are acceptable, but the predicted buff forces of 1,824 to 1,850 kN (410 thousand to 416 kips) may be slightly high for coupler and draft gear. The modelling clearly indicates that improper train handling can result in extremely high buff and draft forces. Potential for track panel shift on 37.5 tonne/axle trains on curves without well-maintained spirals shows the importance of track maintenance, particularly for curves.

References

1: Association of American Railroads, "Manual of Standards and Recommended Practices", 2007.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 98 PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE Edited by: J. Pombo Paper 28 Analysis of Longitudinal Forces in Heavy and Long Trains G.F.M. dos Santos¹, R.S. Barbosa² and R. Joy³ ¹Innovation and Development Department, Vale S.A, Vitoria, Brazil ²Polytechnic School, University of São Paulo, Brazil ³Transportation Technology Center Inc., Pueblo, Colorado, United States of America doi:10.4203/ccp.98.28 purchase the full-text of this paper Full Bibliographic Reference for this paper G.F.M. dos Santos, R.S. Barbosa, R. Joy, "Analysis of Longitudinal Forces in Heavy and Long Trains", in J. Pombo, (Editor), "Proceedings of the First International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 28, 2012. doi:10.4203/ccp.98.28 Keywords: rolling stock design, modelling, simulation, long trains, in-train forces, heavy haul. Summary Vale S.A is the largest mining and railroad company in Brazil. Vale intends to increase axle loads from 31.5 tonne, to 32.5 tonne, and eventually to 37.5 tonne on its 900 km railroad in northern Brazil, named Estrada de Ferro Carajás (EFC). Existing wagons (GDT) are being upgraded from 31.5 to 32.5 tonne axle load capacity. New GDU wagons are being procured to operate at 37.5 tonne axle loads. Mathematical modelling was conducted to evaluate the in-train forces using TOES^TM and NUCARS® software at 31.5, 32.5 and 37.5 tonne axle loads. The most critical section was selected for this analysis. The section includes a sag, where a loaded train must negotiate a 0.96 percent decent followed by a 0.36 percent ascent. The Association of American Railroads (AAR) design requirements for freight wagons to be used in unit train operations [1] specify that the wagon structure be designed for 1,557 kN (350 kips) buff and 2,224 kN (500 kips) draft and be able to withstand 4,448 kN (1,000 kips) compressive load. For GDT wagons, limits of 1,557 kN (350 kips) buff and draft forces are proposed based on AAR wagon design limits. Predicted forces are well below these limits. The risk of jack-knifing and string lining is minimal at the predicted forces. Fatigue performance of couplers is currently being investigated. For GDU wagons the risk of flange climb derailment and rail roll over are acceptable. The risk of track panel shift is acceptable on curves with well-maintained spirals but not acceptable on curves without well-maintained spirals under high buff conditions. The predicted draft forces are acceptable, but the predicted buff forces of 1,824 to 1,850 kN (410 thousand to 416 kips) may be slightly high for coupler and draft gear. The modelling clearly indicates that improper train handling can result in extremely high buff and draft forces. Potential for track panel shift on 37.5 tonne/axle trains on curves without well-maintained spirals shows the importance of track maintenance, particularly for curves. References 1 Association of American Railroads, "Manual of Standards and Recommended Practices", 2007. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £110 +P&P)
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