Sideframe with increased fatigue life having longer cross-sectional thickness transition zone

An improved AAR standard 100 ton truck sideframe having a longitudinal axis, said improved sideframe comprising:

• a longitudinally extending upper compression member having a front end, a back end, and a midpoint therebetween, said upper compression member front end having a downwardly projecting front pedestal jaw depending therefrom and said upper compression member back end having a downwardly projecting back pedestal jaw depending therefrom;
• a longitudinally extending lower tension member generally parallel to said upper compression member having a central portion with a first end and a second end, said first end interconnected to an upwardly extending first diagonal arm and defining a first bend point, said second end interconnected to an upwardly extending second diagonal arm and defining a second bend point, each of said diagonal arms extending upwards to and connecting with a respective upper compression member end at a respective said pedestal jaw;
• and
• a pair of vertically extending columns disposed in proximity to said sideframe midpoint, each of said columns being longitudinally spaced fore and aft of said sideframe midpoint and connecting said upper and lower members together;
• said upper compression member having a top wall with a cross-sectional wall thickness, a bottom wall with a cross-sectional wall thickness, and a pair of arcuate side walls having respective cross-sectional wall thicknesses, said arcuate side walls connecting said upper and bottom walls, said upper, bottom, and arcuate side walls cooperating to define a core which continuously extends between said front and back pedestal jaws,
• said top wall of said upper compression member having a first cross-sectional wall thickness of about 0.75 inches (1.905 cm) approximate to and above each of said vertical columns and a second and thinner cross-sectional wall thickness of about 0.50 inches (1.27 cm) longitudinally disposed between six inches (15.24 cm) and twelve inches (30.48 cm) from said respective first cross-sectional wall thickness, said top wall of said upper compression member gradually decreasing in cross-sectional wall thickness from said first cross-sectional wall thickness to said second cross-sectional all thickness, wherein said gradually decreasing cross-sectional wall thickness increases the static strength of said sideframe such that said improved 100 ton AAR standard sideframe can be loaded with 110 tons of payload without reaching the AAR ultimate loading limits set for a standard AAR 100 ton sideframe, and
• wherein said lower tension member includes two core support holes having additional metallic mass, one of said two holes being located on said first upwardly extending diagonal arm and the other of said two holes being located on said second upwardly extending diagonal arm, each of said core support holes substantially equal in size and second modulus, with each of said core support holes experiencing substantially equivalent flexure stresses in the area around said holes, said flexure stresses around said holes being lower in magnitude than at other points of loading along said sideframe, each of said core support holes sized such that said magnitude of flexure stresses around said holes, when divided by said section modulus, results in a ratio which is smaller than a ratio derived from a core support hole without the additional mass,
• said core support holes allowing an AAR standard 100 sideframe to meet AAR dynamic testing standards set for a 100 ton sideframe although said sideframe is loaded and flexured with 110 tons of payload.