Patent ID: 7972078

Claim:
A power transmission mechanism comprising: a shaft; a hub; a shaft tooth section formed on the shaft and comprising a plurality of shaft teeth; a hub tooth section formed on the hub and comprising a plurality of hub teeth; and a retaining ring, wherein the hub is axially secured relative to the shaft by the retaining ring in a position disposed around the shaft while holding the shaft tooth section and the hub tooth section in engagement with each other; wherein said shaft tooth section has a crowned peak having a varying tooth thickness along an axial length of the crowned peak and a shaft tooth valley; wherein said hub tooth section has a peak opposing and engaging said shaft tooth valley of said shaft tooth section, said peak of said hub tooth section having a constant tooth thickness along an axial length, and a hub tooth valley having a constant inside diameter in an axial direction of the shaft; wherein the shaft tooth valley includes first and second portions having different outside diameters and connected by a first step region sloping from a first starting point at an end of the first portion to an end of the second portion in a direction extending toward the hub tooth section; wherein said peak of said hub tooth section includes first and second peak portions having different inside diameters and connected by a second step region sloping from a second starting point at an end of the first peak portion to an end of the second peak portion in a direction extending away from said shaft tooth section; wherein the first starting point of the first step region and the second starting point of the second step region are offset from each other in the axial direction of the shaft by a predetermined distance; and wherein the end of the second portion and the end of the second peak portion are offset from each other in the axial direction of the shaft by a predetermined distance.