Roller needle roller

According to the actual production situation of roller needle roller bearings in China, the size range of light series of ring-retaining roller needle bearings has been enlarged; the diameter of bolt radial oil holes and the diameter of axial oil holes at both ends of bolts have been increased, and their symbols have been added; bearing models have been added in the dimension table for convenience of use; and the requirements of surface roughness have been increased. These technical differences are marked vertically in a single line at the margin of the clauses they cover.