Heavy-duty railcars carry greater than typical payloads by employing additional wheelsets to lessen wheel/rail contact stresses. Rather than the common 4-axle designs, these cars may have up to 16 axles supporting one deck. Traditionally, these car types have not performed as well as desired. As a response, designers have created depressed center body styles to lower the overall center-of-gravity (CG) height. Such designs lead to more complexity and expense. In this investigation, a heavy-duty 8-axle flatcar has been modeled, both with a flat carbody and a depressed body style. Simulations of harmonic roll perturbations were performed using various CG heights, track perturbation wavelengths and operating speeds. Results include comparisons of design versus performance trade-offs.

Kratville, et.al., 1997 Car & Locomotive Cyclopedia of American Practices, 6th Edition, pg. 137, Simmons-Boardman Books, Inc., Omaha, NE.
Kasgro Company’s listing and drawings of their heavy-duty car fleet, 05/2006. http://www.triarchy.com/kasgro/specs.asp
NUCARS® User Manual, Chapter 7, Cusp Equation, Section 7.6.1, 2006, Transportation Technology Center, Inc, Pueblo, CO.
Association of American Railroads, 2003, Manual of Standards and Recommended Practices (MSRP), “Truck Performance Specification for Railcars,” Specification M-976, Washington, DC.
Association of American Railroads, 1993, Manual of Standards and Recommended Practices, Part C, Volume II, Chapter XI, Service-Worthiness Tests for New Freight Cars, Washington, DC.
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