EFFECTS OF LONGITUDINAL IMPACT FORCES ON FREIGHT CAR TRUCK BOLSTERS

The design of truck bolster center plate rims was investigated as a result of increased reports of their failure on 100-ton capacity freight cars. The damage occurs when cars are coupled at moderate to high speeds, since the rapid deceleration of the truck causes high loads between the truck and body bolsters. Test measurements were made on an unloaded 100-ton hopper car impacting a string of loaded cars. The forces between the truck and body bolsters on the moving car were determined at impact speeds from 2.9 to 9.2 mph. Tests were made with two different energy absorbing capacities of draft gear. Loads at the truck-bolster/body-bolster interface averaged approximately 40,000 lbs for impact velocities up to 5 mph and reached 100,000 lbs at 7 mph. A peak load of 160,000 lbs was measured at 8.4 mph. Within the lower speed range there were no significant differences in load associated with the two draft gear, but at 6.7 mph the loads with the higher capacity gear were 25 percent less. Strain gages placed near the center rim indicated yielding on the first impact at 2.9 mph. Additional yielding continued as the impact velocity was increased. A finite-element stress analysis showed that loads of the magnitude measured on the test would cause severe stresses in the center plate rim and that yielding of the material would be expected. Several potential modifications of the truck bolster center plate rim were analyzed which showed that significant improvements could be obtained by making the rim wider and by increasing the radius of the fillet at the inside of the rim.

  • Supplemental Notes:
    • The project was sponsored by US DOT, Federal Railroad Administration's Office of Research and Development. IIT Research Institute was under contract to US DOT, Transportation Systems Center.
  • Corporate Authors:

    IIT Research Institute

    10 West 35th Street
    Chicago, IL  United States  60616

    Transportation Systems Center

    55 Broadway, Kendall Square
    Cambridge, MA  United States  02142

    Federal Railroad Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Johnson, M R
  • Publication Date: 1974-9

Media Info

  • Features: Appendices; Figures;
  • Pagination: 42 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00099362
  • Record Type: Publication
  • Source Agency: Federal Railroad Administration
  • Report/Paper Numbers: FRA ORD&D-75-10 Final Rpt.
  • Contract Numbers: DOT-TSC-727
  • Files: NTIS, TRIS, USDOT
  • Created Date: Aug 27 1976 12:00AM