TRIPOD TYPE CONSTANT VELOCITY UNIVERSAL JOINT

PROBLEM TO BE SOLVED: To ensure the sufficient strength of the root part of a leg shaft. SOLUTION: A tripod type constant velocity universal joint is provided with a trunnion member 22 formed such that a serration hoe 9 is formed through, three flat surfaces 11 are formed at equal intervals in a peripheral direction on the outer periphery of a boss part 10, leg shafts 1 are radially protruded from the respective flat surfaces 11, and a plurality of needle rollers are arranged in a rolling manner on the outside diameter surfaces 12 of each leg shaft 1. In the trunnion member 22, the root part 23 of the leg shaft 1 forming a boundary between the outside diameter surface 12 of the leg shaft 1 and the flat surface 11 of the boss part 10 crossing the outside diameter surface 12 forms a continuous rounding surface with a given curvature r1 with radius through simultaneous grinding of the outside diameter surface of the leg shaft and the flat surface of the boss part after heat treatment.