Support structure carrying thrust load of transmission, method of manufacturing thereof and thrust needle roller bearing

A thrust needle roller bearing used for a support structure carrying a thrust load of a transmission having an input shaft with its rotation changed stepwise or continuously to be transmitted to an output shaft, wherein

• the thrust needle roller bearing carries a thrust load generated by rotation of said input shaft or said output shaft, and said thrust needle roller bearing has needle rollers arranged in two rows,
• said thrust needle roller bearing has a plurality of needle rollers and two annular cages, said two annular cages respectively have a plurality of pockets having a radial length slightly larger than that of said needle rollers, roller holder portions formed at said plurality of pockets respectively are structured to allow said two cages to hold said needle rollers therebetween in the direction from above and below, and said needle rollers are arranged in two rows in each of said plurality of pockets,
• said two cages are caulked on both of the radially outermost end and the radially innermost end of said two cages, and a flat portion having a cross-sectional height lower than that of said roller holders is provided between a caulked portion produced by caulking of said two cages and corresponding ends of said needle rollers,
• the radial length of the roller holder portions is smaller than the total radial length of the needle rollers in the two rows, and
• the pockets where the needle rollers are placed each have an end located at the flat portion of the cages.