Principle and Application of Cross Shaft Universal Joint

The cross shaft, also known as the ten-byte universal joint cross, is a component that realizes variable-angle power transmission. It is used to change the position of the transmission axis. It is the "joint" part of the universal transmission of the automobile drive system. The cross-shaft rigid universal joint is a variable speed universal joint widely used in automobiles, and the maximum angle of intersection between two adjacent shafts is allowed to be 15゜～20゜. The cross shaft is one of the key parts of the cross shaft rigid universal joint.

Principle and Treatment:

The failure of the universal joint of the transmission shaft is mainly due to the wear of the journal and the bearing and the bending and deformation of each journal, which causes the center lines of the cross shafts to be not on the same plane, or the center lines of two adjacent shafts are not vertical. Due to the excessive wear gap between the universal joint cross shaft journal and the bearing, the cross shaft shakes 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 transmission shaft to make abnormal noises 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 point of view of use, and it is generally kept at about 0.01mm. If it exceeds 0.13mm, vibration and noise of the drive shaft will occur. If the cross shaft journal wears out of the groove, the groove is very deep and should be repaired or replaced. If surfacing and inserting repairs are used, heat treatment and grinding are required. After processing, the out-of-roundness of each journal is required to be 0.01mm, and the taper cannot be large (the length of 20mm can not be greater than 0.01mm). To check the verticality of two adjacent axes, be sure to be vertical. After processing and repair, the axis of each journal should be in the same plane.

When the vehicle is running, because the torque transmission direction is the same, the force direction of the cross shaft is also the same. Over time, the unilateral wear of the cross shaft journal will be caused. As time goes by, the force side of the cross shaft will wear more and more, and grooves will cause looseness. You can use the cross shaft to rotate 90° relative to the original position, which can extend the use time. When assembling, pay attention to the side with the oil nozzle facing the drive shaft. The universal joint fork should rotate freely on the cross shaft, and there should be no jamming and no axial gap. Grease should be injected frequently in daily maintenance to prevent the wear of the cross shaft journal and bearings due to lack of grease.

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