I LLINOI S UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN PRODUCTION NOTE University of Illinois at Urbana-Champaign Library Large-scale Digitization Project, 2007. UNIVERSITY OF ILLINOIS BULLETIN ISSUED WEEKLY Vol. XXIV July 12, 1927 No. 45 [Entered as second-class matter December 11, 1912, at the post office at Urbana, Illinois, unde the Act of August 24, 1912. Acceptance for mailing at the special rate of postage provided for in section 1103, Act of October 3, 1917, authorized July 81, 1918.] FREIGHT TRAIN CURVE RESISTANCE ON A ONE-DEGREE CURVE AND ON A THREE-DEGREE CURVE BY EDWARD C. SCHMIDT BULLETIN NO. 167 ENGINEERING EXPERIMENT STATION PUBLIBHED BY TEH UNIVbzaITsY ILLINOIS, URiBAN SPac: TwzTr-rznlV Camt THE Engineering Experiment Station was established by act of the Board of Trustees of the University of Illinois on December 8, 1903. It is the purpose of the Station to conduct investigations and make studies of importance to the engineering, manufacturing, railway, mining, and other industrial interests of the State. The management of the Engineering Experiment Station is vested in an Executive Staff composed of the Director and his Assistant, the Heads of the several Departments in the College of Engineering, and the Professor of Industrial Chemistry. This Staff is responsible for the establishment of general policies gov- erning the work of the Station, including the approval of material for publication. All members of the teaching staff of the College are encouraged to engagg in scientificresearch, either directly or in cooperation with the Research Corps composed of full-time research assistants, research graduate assistants, and special investigators. To render the results of its scientific investigations available to the public, the Engineering Experiment Station publishes and distributes a series of bulletins. Occasionally it publishes circu- lars of timely interest, presenting information of importance, compiled from various sources which may not readily be acces- sible to the clientele of the Station. The volume and number at the top of the front cover page are merely arbitrary numbers and refer to the general publica- tions of the University. Either above the title or below the seal is given the number of the Engineering Experiment Station bul- letin or circular which should be used in referring to these pub- lications. For copies of bulletins or circulars or for other information address THE ENINEEMING EXPERIMENT STATION, UNIVEnSITY OF ILLINOIS, URBANA, ILLINOIS UNIVERSITY OF ILLINOIS ENGINEERING EXPERIMENT STATION BULLETIN NO. 167 JUNE, 1927 FREIGHT TRAIN CURVE RESISTANCE ON A ONE-DEGREE CURVE AND A THREE-DEGREE CURVE BY EDWARD C. SCHMIDT PROFESSOR OF RAILWAY ENGINEERING ENGINEERING EXPERIMENT STATION PUBLISHED BY THE UNIVERSITY OF ILLINOIS, URBANA MEOW CONTENTS PAGE I. INTRODUCTION . 7 1. Introduction . 7 2. Acknowledgment . 8 II. TRACK AND TRAINS .. .. 3. Test Track .. 4. Trains. III. TEST PROCEDURE, METHODS, AND C()NDITION s . 13 5. Test Program . 13 6. Immediate Purpose of Tests . 13 7. Correction for Grade . 14 8. Correction for Acceleration . 14 9. Journal Temperature . 17 10. Correction for Wind Resistance . 18 11. Weather Conditions . 19 12. Methods of Calculation 19 IV. RESULTS OF TESTS . 19 13. Immediate Results . 19 14. Graphical Presentation of Immediate Results 21 15. Final Results-Curve Resistance . 25 16. Final Results in Graphical Form . 27 V. DISCUSSION OF RESULTS . 27 17. Divergence Among Final Results .. .. 27 18. Influence of Track Curvature . 30 19. Influence of Speed on Curve Resistance 30 20. Applicability of Results in Freight Service 32 VI. SUMMARY . 35 21. Summary and Conclusions .. 35 PAl E APPENDIX A. TEST TRACK AND TRAINS . 36 22. Curvature . 36 23. Super-elevation . .37 24. Track Gauge . 37 25. Profile .... .. ... 38 26. Rail Wear . 38 27. Train Tonnage . 39 28. Car Dimensions . .. .39 29. Condition of Wheels and Bearings . .. 39 30. Side-Bearing Clearance . 39 APPENDIX B. IMMEDIATE RESULTS OF TESTS . .. 40 LIST OF FIGURES NO. PAGE 1. Diagram of Test Track ................. .......................... 9 2. Test Car and Test Crew.......... .............................. 10 3. One of the Loaded Trains on Three-Degree Curve ...................... 12 4. Recording Apparatus and Chart in Dynamometer Car ................... 14 5. Circuit Breakers which Operated Pens on Chronographs................. 16 6. Recording Thermometer Used to Measure Car Journal Temperature ..... 17 7. Test Results for Train No. 2 on Straight Track, One-Degree Curve, and Three-Degree Curve .................. ........................ 20 8. Net Train Resistance for Train No. 1 on Straight Track and Both Curves.. 21 9. Net Train Resistance for Train No. 2 on Straight Track and Both Curves. 22 10. Net Train Resistance for Train No. 3 on Straight Track and Both Curves. 24 11. Net Train Resistance for Train No. 4 on Straight Track and Both Curves. 24 12. Net Train Resistance for Train No. 5 on Straight Track and Both Curves. 25 13. Curve Resistance at 10, 20, and 30 Miles per Hour for Each of the Five Trains, and Average Values for All Trains ........................ 27 14. Diagram of Forces Acting on Car on Curve ........................... 32 15. Contour Limits of Worn Rail Heads on Tangent and Curves............. 34 LIST OF TABLES NO. PAGE 1. Train Data .............. .......................... ........... 11 2. Test Program .................................................... 13 3. Summary of Test Conditions ............... ...................... 19 4. Values of Resistance on Straight Track and on Curves at 10, 20, and 30 Miles per Hour, and Derived Values of Curve Resistance ........... 23 5. Final Values of Curve Resistance, at Various Speeds for Each of the Five Trains, and Average Values for All Trains ......................... 26 6. Tonnage Record for All Trains ......... ......................... .. 38 7. Side-Bearing Clearance ................... ........................ 40 8. Values of Resistance and Speed Obtained from Tests Made with Train No. 1................... ....... ............................... 41 9. Values of Resistance and Speed Obtained from Tests Made with Train No. 2........................................... ............. 42 10. Values of Resistance and Speed Obtained from Tests Made with Train No. 3 ..... .................... .. ..................... 43 11. Values of Resistance and Speed Obtained from Tests Made with Train No. 4 ............... ........................................ 44 12. Values of Resistance and Speed Obtained from Tests Made with Train No. 5 ............ ........................................... 45 FREIGHT TRAIN CURVE RESISTANCE ON A ONE-DEGREE CURVE AND A THREE-DEGREE CURVE I. INTRODUCTION 1. Introduction.-When a train runs on curved track there is a certain excess of resistance over that encountered when it runs on straight track. This excess is termed curve resistance, and it is usually expressed in pounds per ton of train weight per degree of curve. Its magnitude is generally assumed to lie between the limits of 0.3 pound and 1.0 pound per ton per degree. Very frequently its general average value is assumed to be one-half pound per ton per degree. There are few published records of direct determinations of curve resistance for American cars and track; and the scarcity of experimental data has seemed to warrant the publication of the results here presented. The practice of compensating curves on grades-that is, so reducing the grade through the curve that the combined grade and curve resist- ances remain equal to the grade resistance on the adjacent tangent- has, when successful, produced indirect evidence concerning the mag- nitude of curve resistance; and the Manual of the American Railway Engineering Association gives rules for compensating curves which imply a very detailed and definite knowledge of curve resistance. There remains, nevertheless, great divergence of opinion as to its amount. This bulletin presents the results of tests made with five freight trains on a one-degree curve and a three-degree curve. The final results are given in Table 5 on page 26 and in Fig. 13 on page 27. The results are discussed in Chapter V and the discussion is summarized on pages 35 and 36. The test results relate exclusively to the resistance of the cars com- posing the train-the curve resistance of the locomotive is not discussed. The results apply only to freight trains with four-wheeled trucks, al- though the resistance of our-wheeled truck passenger cars of similar wheel-base is probably not very different. Throughout this report the terms "resistance" and "net resistance" mean the number of pounds of tractive force required for each ton of train weight in order to keep the train moving on straight and level track, at uniform speed, in still air. The term "resistance on the curve" means the number of pounds of tractive force required for each ton of train weight in order to keep the train moving on a level curve, at ILLINOIS ENGINEERING EXPERIMENT STATION uniform speed, in still air. "Curve resistance" is the difference between resistance on the curve and net resistance, divided by the degree of curve; and it is expressed therefore in pounds per ton per degree of curve. The tests were undertaken primarily to determine the relative merits of three designs of freight car trucks, that is; to determine the effects of truck design upon train resistance on straight track and on curves. In arranging the tests it was clear from the outset that they would provide an exceptional