摘要：The universal joint is one of the most critical parts of both the engine and the transmission system of a vehicle. After long-term use, however, some vibration and abnormal noise might occur in it, which may lessen safety while driving. In this article, we investigate faults associated with the double cross universal joint, including looseness, wear, and intermediate shaft torsional deformation. First, we propose a transmission model and a new fault model for this joint. Then, the model parameters of the optimal transmission performance are analyzed. Finally, the main contribution of this article is in discussing the transmission performance as related to looseness, wear, and the intermediate shaft torsional deformation. Our results show that when the angle of the two universal joints is consistent, the phase angle equals 90 and the angular velocity of the output shaft becomes constant, which indicates an optimal transmission performance. When the universal joint is exhibiting looseness, the performance of the angular velocity of the output shaft and the transmission becomes worse as the looseness increases. For both wear and the intermediate shaft torsional deformation, the output angular velocity is also unstable. If looseness occurs at the same time as one of these two faults, the instability will be superimposed and the transmission performance will be even worse. This article provides reference for analysis of faults of the universal joint and its diagnosis; for example, it provides suggestions for when the universal joint should be inspected for repairs or replaced.
