Technical Reports

General Models for Lateral Stability Analyses of Railway Freight Vehicles

  • 15
  • Jun
  • 1977
AUTHOR: E. H. Law, J. A. Hadden, N. K. Cooperrider
OFFICE: RPD
REPORT NUMBER: FRA/ORD-77/36
SUBJECT: Freight Operations, Track/Train Interactions
KEYWORDS: Train-Track Dynamics, Rail Vehicles and Components, Freight Car Design, Hunting
ABSTRACT: This report presents the development of general analytical models for use in exploring the nature of freight car hunting and for finding means of controlling the hunting behavior. These models result from one aspect of the "Freight Car Dynamics" research project conducted by Clemson and Arizona State Universities in cooperation with the Association of American Railroads. This effort is directed at developing models to describe rail vehicle curving behavior and response to track irregularities in addition to those models presented in this report that deal with hunting. First, a model of a wheel set with lateral, yaw, and axle torsional degrees of freedom is developed. Secondly, two such wheelsets are included in a general model of a 9 degree of freedom truck that has 1 lateral, yaw, and warp degrees of freedom in addition to relative lateral and yaw motions of the wheelsets with respect to the truck frame. By suitable choices of primary suspension-elements, this general model may be specialized to become (1) a roller-bearing freight, (2) a plain-bearing freight truck, (3) a roller-bearing truck with primary suspension elements, (4) a passenger truck, (5) a generic model of a freight truck with interconnected wheelsets, or (6) a rigid truck. Finally, two such truck models are combined with a car body that has lateral, yaw, and roll rigid body degrees of freedom plus two degrees of freedom that serve to approximate the first lateral bending and torsional modes. For all three models, the effects of design parameters on the critical speed for hunting are examined.
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