1. The flange connections (or connecting bolts) of the transmission shaft are loose, causing abnormal noise.

2. The oil leakage of the crosshead and the grease injection sleeve caused by the grease leakage of the crosshead (grease injection of the crosshead is too large during the working period) and the damage of the crosshead bearing due to the lack of grease and grease injection of the crosshead bearing.

3. The universal cross shaft is assembled too tightly.

4. The loose fit between the sleeve and the fork hole of the universal joint and the loose bolt of the support plate lead to the rotation of the sleeve, resulting in excessive wear of the fork hole of the universal joint and abnormal noise caused by looseness.

5. The spline of the second shaft of the transmission and the internal spline of the flange are worn too much, resulting in looseness and abnormal noise.

6. The fixing bolts of the intermediate support bracket of the transmission shaft are loose, the fit between the intermediate support and the Journal of the intermediate transmission shaft is loose, the fit between the rear spline and the flange keyway of the intermediate transmission shaft is loose, and the rear nut is loose.

7. The middle support bearing of the transmission shaft is scattered, the bearing raceway is damaged, the bearing lubrication is poor, and the bearing is excessively worn and loose.

8. The installation position of the intermediate support bracket of the transmission shaft is skewed, the bearing preload is adjusted improperly, the rubber spacer is damaged, and the deflection of the bracket position is caused by excessive or too small tightening torque of the fixing bolt of the intermediate support bracket.

9. The universal joint forks at both ends of the transmission shaft are not in the same plane, which destroys the constant speed arrangement and causes abnormal noise.