Improved performance of railcar/rail truck interface components
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The objective of this research is to improve the railcar/rail truck interface by developing a low maintenance bearing interface with a favorable friction coefficient. Friction and wear at the center bowl/center plate bearing interface cause high turning moments around curved track, wear of truck components, and increased detrimental dynamic effects. The recommended improvement of the rail truck interface is a set of two steel inserts, one concave and one convex, that can be retrofit to center bowls/center plates. The insert geometry addresses concerns about maintaining favorable pressure distribution on existing components, minimizing overall height increase to accommodate existing infrastructure, and retaining railcar stability. The stability of the railcar upon the design inserts has been ensured when the instantaneous center of rotation of the railcar body is above the railcar center of gravity. The damping ratio provided by the frictional moment within center bowl is 240 and eliminates the possibility of dynamic amplification. Using a 90 inch radius of curvature ensures stability and requires a 0.5 inch diameter reduction of the existing center plate for a gap of 1/16 inch. The increase in railcar height for the specific design is 0.71 inches which can be absorbed by either grinding of the center plate or new manufacturing dimensions. The design is feasible for small travel values corresponding to small vertical gaps at the side bearings. In addition to geometry alterations, the bearing surfaces are coated with a protective metallic layer. The literature suggests that optimum friction coefficients between bearing elements in the center bowl/center plate interface may reduce turning moments of the truck, wear of truck components, and detrimental dynamic effects such as hunting. Axial-torsional tests determined friction coefficient estimates and wear properties for a matrix of various metallic protective coatings and steel. Tungsten carbide-cobalt-chrome has a favorable coefficient of 0.3 under standard center bowl/center plate contact conditions.
Story, Brett Alan (2007). Improved performance of railcar/rail truck interface components. Master's thesis, Texas A&M University. Available electronically from