US Patent 7695372 Yoke for universal joint and universal joint

A yoke for universal joint includes a cylindrical base, and a pair of arms extending from an end of the base in parallel to a center axis of the base. Each of the arms is formed with a support hole for supporting a corresponding trunnion of a cross shaft via a bearing. The support hole of each arm has a center axis extending in a direction orthogonal to the center axis of the base. A relief portion including a concave curved surface is formed at the end of the base. The concave curved surface of the relief portion has a center of curvature located at place offset from a center of a joint 1 toward a distal end of the arm.