Patent ID: 8771086

Claim:
A fixed constant velocity universal joint, comprising: an outer joint member having an inner surface provided with track grooves; an inner joint member having an outer surface provided with track grooves paired with the track grooves of the outer joint member; a plurality of balls for transmitting torque, the plurality of balls being interposed between the track grooves of the outer joint member and the track grooves of the inner joint member; and a cage for holding the plurality of balls, the cage being interposed between the inner surface of the outer joint member and the outer surface of the inner joint member, the fixed constant velocity universal joint comprising a lubricating grease sealed therein, wherein the plurality of balls comprises eight balls, wherein a spherical angle of the outer joint member is within a range from 17° to 18.5°, wherein the outer joint member comprises a spherical inlet provided with cut out portions for incorporation of the cage, wherein a surface roughness of each of the plurality of balls is Ra 0.15 μm or less, wherein a surface roughness of a counterpart surface on which a corresponding one of the plurality of balls rolls is within a range from Ra 0.4 μm to Ra 1.8 μm so as to be higher than the surface roughness of each of the plurality of balls, and wherein an additive composition of the lubricating grease comprises a base oil, a diurea compound, molybdenum dithiocarbamate, zinc dialkyldithiophosphate, melamine cyanurate, molybdenum disulfide, and calcium salt of alkylaromatic sulfonic acid.