The gearbox is the core component to ensure that the truck can pull and run fast. It is very precise. In addition to the quality problems of individual transmissions, a large number of faults in use are caused by improper maintenance and incorrect operation.
Recently, a case of “gearbox burning” appeared in a post “precautions for gearbox burning” on the truck Home Forum of oven.
Due to the lack of lubricating oil in the transmission of this card friend, the transmission “burned”, resulting in abnormal noise when the transmission was sliding.
After inspection, the first shaft gear of the transmission and the intermediate shaft transmission gear; The overdrive gear of the second shaft and the overdrive gear of the intermediate shaft are seriously worn.
According to the owner’s description, the gearbox is an abnormal noise fault after lack of oil. According to the disassembled gear picture, there is quite a lot of black sludge on the gear of oven.
Gearbox burning is a popular term, which generally refers to the lack of lubrication or overheating damage of the gearbox. After the burning box occurs, the gear, bearing and bearing seat will be worn and damaged, and even the output shaft will be distorted in serious cases.
In the gear failure analysis, the following explanations can be seen:
Based on the above explanation, we sorted out the following reasons for tooth surface wear caused by insufficient lubrication:
1. The local temperature at the gear meshing is too high and the lubricating oil film is damaged.
2. Overheating caused by insufficient lubrication, high operating temperature, high tooth surface contact stress or high speed.
3. Poor lubrication and strong effect of high pressure, the result of “crawling” on the tooth surface, and plastic flow on the tooth surface caused by low speed and vibration.
4. The severe temperature rise caused by abnormal lubrication causes the thermoplastic deformation of gear teeth, and the excessive load causes the cold plastic deformation.
In the above two pictures, the tooth surface wear and plastic flow caused by insufficient lubrication are more clearly shown.
As mentioned above, after the damage of the first shaft bearing in the gearbox, the gear is in abnormal contact, forming an abnormal impact load. Then, the hardened layer on the gear surface disappears due to overheating and wear, resulting in the plastic deformation of the gear tooth surface caused by the impact load.
In vernacular, the bearing is damaged due to insufficient lubrication, resulting in excessive fit clearance and impact. At the same time, due to the lack of lubrication of the gear, the surface hardening layer disappears due to overheating wear, resulting in wear and deformation of the tooth surface.
Therefore, when we repair the parts failure caused by overheating of the transmission, truck house recommends:
For the gearbox burning box, completely disassemble the gearbox, check the damage of each bearing hole, bearing and gear of the gearbox in detail, and measure whether the accuracy of parts has changed.
If the damage is not serious, the parts can be replaced for maintenance after careful inspection and measurement to confirm that there is no deformation and ablation.
For serious burning, it is recommended to directly replace the transmission assembly.
By simply replacing parts to repair the gearbox, the driving hazard is also very large. Because the inspection is not enough, only the things seen by the eyes are replaced, which is likely to cause subsequent hidden trouble.
There is a saying called “how good you are to the car, the car will be good to you”. For those who make money, the vehicle can run stably for a long time only by maintaining good maintenance. For vehicles with faults, normal and rigorous maintenance methods should be used to ensure the subsequent use of vehicles.