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.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1468 |
| Date | 15 May 2009 |
| Creators | Story, Brett Alan |
| Contributors | Fry, Gary T. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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