The failure of the drive shaft universal joint is mainly due to the wear of the journal and the bearing and the bending deformation of each journal, so that the center line of each axis of the cross shaft is not on the same plane, or the adjacent two-axis center lines are not perpendicular. Due to the excessive wear clearance of the universal joint cross shaft journal and the bearing, the cross shaft sways during operation, causing the center line of the transmission shaft to deviate from its rotation center line, causing the transmission shaft to vibrate and the abnormal sound of the transmission shaft during operation. phenomenon. Wear is mainly caused by lack of lubrication.

The wear of the universal joint cross shaft journal and bearing should not exceed 0.02~0.13mm from the use condition, and is generally maintained at about 0.01mm. If it exceeds 0.13 mm, the transmission shaft will vibrate and sing. If the cross shaft journal wears out of the groove, the groove is deep and should be repaired or replaced. If surfacing and insert repairs are used, heat treatment and grinding are also required. After processing, the non-circularity of each journal is required to be 0.01 mm, and the taper cannot be large (not more than 0.01 mm in length of 20 mm). To check the perpendicularity of the adjacent two axes, be sure to be vertical. After machining and repairing, the axes of the journals should be in the same plane.

When the vehicle is running, the direction of the force transmitted by the cross shaft is also the same because the directions of the torque transmission are the same. Over time, it causes the unilateral wear of the cross shaft journal. As time goes by, the side of the cross shaft will wear and increase, and the groove will be so loose that it will make a sound. It is possible to rotate the cross shaft by 90° with respect to the original position, which can extend the use time. When assembling, pay attention to the side with the grease nipple facing the drive shaft. The universal joint fork should rotate freely on the cross shaft. There should be no stagnation or axial clearance. Grease should be inspected during normal maintenance to prevent wear of the cross shaft journal and bearing due to lack of grease.