Why does the main drive shaft produce abnormal sound?
发布时间：2016.07.23 新闻来源：邢台远拓汽车零部件制造有限公司
(1) phenomenon
A new Dongfeng truck with less than 2 months, the driver in gear acceleration and reflect, coasting in neutral, chassis were issued a "cough cough Da Da" sound, no-load is most obvious, less noise when fully loaded, the driving wheel off the ground in gear acceleration and slip test, which drive shaft noise.
(2) reasons and analysis
After dismantling, it is found that the universal joint of the main drive shaft is loose, but the slip spline clearance is normal, and the radial runout error of the drive shaft meets the requirements. After the replacement of the two sets of cross shaft assembly, the failure has not been ruled out. Dismantling the intermediate shaft and drive axle housing for inspection, found the problem, replace the driving shaft noise has not ruled out. After careful observation, found that the car's main transmission shaft drive angle is particularly large, the original owner in order to overload, in the rear suspension on both sides of each additional two leaf springs. Because the main shaft are short, increase the leaf spring rear frame from the ground up, and the drive axle height unchanged, which increases the main shaft angle, the angle between the shaft is connected with the universal joint exceeds the allowable value (usually allow the angle of 15 DEG ~20 DEG), so that the transmission shaft and universal section of torsional vibration in rotation, resulting in abnormal noise.
Due to the violation of the use requirements, after increasing the thickness of the leaf spring, the normal transmission angle of the original intermediate drive shaft and the main transmission shaft is destroyed, resulting in the early damage of the universal joint.
In order to eliminate the abnormal sound, the intermediate transmission support can be moved down to reduce the angle of the main transmission shaft, and a pad with a thickness of about 40mm is added on the upper cover of the intermediate support, and the abnormal sound is eliminated.
Although this method eliminates the abnormal noise of the main drive shaft, it destroys the normal position between the engine and the middle drive shaft. In the overall design of the car, the car in full, to ensure that the engine drive shaft axis and axis changes a little, in order to achieve constant velocity drive motor axis in suspension backward angle is about 7 degrees, if the increase in intermediate transmission support plate, fixing screws will make the engine clutch, gearbox shell at the risk of loosening caused the early damage of the clutch housing.
Therefore, the thickness and quantity of leaf springs can not be arbitrarily increased or changed during use.
