APPENDIX B WITH 100,000 LBS. DRAWBAR FORCE 89 ft. CAR & APPENDIX B 50 ft. CAR 15° CURVE 13° 28° LATERAL COMPONENT REACTING 12,190 LBS. E SHORT CAR E LONG CAR LATERAL COMPONENT REACTING 23,150 LBS. Figure 12. Table 3 shows the steady-state drawbar forces that will produce critical lateral forces for long short car combinations for various degrees of curvature for a car weight of 33.5 tons. 40 60 80 100 120 140 16° N 300,000 lbs. 300,000 lbs. 300,000 lbs. 262,000 197,000 158,000 132,000 113,000 99,000 N N M THOSE WHO ARE RESPONSIBLE FOR THE MAKE UP OF TRAINS 3-7 Many railroads tend to limit the drawbar pull of the locomotive (s) to 250,000 lbs. or less by limiting the tractive effort in the locomotive consists. Most of the very high drawbar forces are experienced when heavy trains are ascending or descending those ruling grades that limit the maximum train tonnage. The three principal factors that are involved in the problems associated with the make-up of long car short car combinations in the train are: The grade and degree of curvature are fixed characteristics of the particular route. The placement of long car short car combinations in a train should vary depending upon the trailing tonnage. For the suggested maximum allowable tonnage to trail an empty long car, which may be used by terminal operating personnel to govern their train make-up procedures, see Table 4. When considering the placement of long car - short car combinations ahead of helper engines, the tonnage and the effective grade under the cars preceding the helper must be considered. The allowable steady-state drawbar forces (buff) because of increased coupler angularity, are approximately 20% higher than draft forces in a given degree of curvature. See Table 5. Tables 4 and 5 do not take into consideration speed or superelevation for trains negotiating curves. However, if the speed and superelevation are in equilibrium, or reasonably close, the guideline table can be effectively used. If speed is significantly different than the equilibrium speed, a further reduction in trailing tonnage for long car - short car combinations must be made. APPENDIX B 100 TABLE 4 Guideline Tonnage to Trail An 85 Ft. Empty Car in Draft 60 120 140 160 Maximum Safe 250,000 | 190,000 140,000 Drawbar Force (lbs.) 110,000 90,000 77,500 67,000 Drawbar Steepness Force/ Of Trailing Grade Ton 0.2% 10.1 24,700 18,800 13,800 10,900 8,890 8,650 6,610 0.4% 14.1 17,700 13,300 9,790 7,700 6,290 5,420 4,690 0.6% 18.1 13,800 10,500 7,720 6,070 4,960 4,280 3,700 0.8% 22.1 11,300 8,590 6,330 4,970 4,070 3,500 3,030 1.0% 26.1 9,570 7,270 5,360 4,210 3,440 2,970 2,560 1.2% 30.1 8,300 6,310 4,650 3,650 2,990 2,570 2,220 1.4% 34.1 7,330 5,570 4,100 3,220 2,640 2,270 1,960 1.6% 38.1 6,560 4,980 3,680 2,890 2,360 2,030 1,760 1.8% 42.1 5,930 4,510 3,320 2,610 2,140 1,840 1,590 2.0% 46.1 5,420 4,120 3,040 2,390 1,950 1,680 1,450 2.2% 50.1 4,990 3,790 2,790 2,190 1,800 1,550 1,340 2.4% 54.1 4,620 3,510 2,590 2,030 1,660 1,430 1,240 2.6% 58.1 4,300 3,270 2,410 1,890 1,550 1,330 1,150 NOTE: Above table based on the following criteria Maximum Drawbar Force based upon Knuckle Strength 250,000 lbs. Grade Resistance 20 lbs./ton/percent grade Rolling Resistance 6.13 lbs./ton for 35 ton cars at 21 MPH APPENDIX B TABLE 5 Guideline Tonnage to Preceed an 85 Ft. Empty Car in Buff Maximum Safe Drawbar Force based upon 250,000 lb. Guideline Drawbar Grade Resistance - 20 lbs./ton/percent grade Rolling Resistance = 6.13 lbs.,/ton for 35 ton cars at 21 mph |