Cross shaft for differential mechanism

The invention relates to a universal joint pin for a differential mechanism. The universal joint pin comprises a base body and four shaft necks. An installation hole is formed in the middle of the base body, the four journals extend in the radial direction of the installation hole and are evenly distributed on the periphery of the base body at intervals, each journal comprises a rod portion and a transition section located at one end of the rod portion and connected with the base body, the section, perpendicular to the axis of the rod portion, of each rod portion is oval, and the section, perpendicular to the axis of the rod portion, of each journal is oval. The elliptical structure is adopted to replace a flat part, so that a gap between a cross shaft and an inner hole of a planetary gear is reserved, oil lubrication is facilitated, a transition sharp corner area between the flat part of a traditional structure and a journal body is eliminated, friction damage caused by huge load change at the transition sha