Maintenance of universal joint cross shaft needle bearing

The universal joint cross shaft needle bearing of the transmission shaft should be lubricated with gear oil. However, it is generally found in automobile maintenance that the needle bearings are lubricated with calcium-based lubricants. In fact, this lubrication method is wrong, which has led to the early damage of a large number of cross shaft needle bearings. During disassembly, it can be clearly seen that the cross shaft journal has a squeezed groove, and the journal and needle roller are seriously lacking in oil.

Why does this happen? It is because the lubricating nozzle of the universal joint cross shaft needle bearing is an ordinary grease nozzle, which creates an illusion for people, and grease has been commonly added for lubrication for a long time.

In fact, it is difficult to add grease to the needle roller bearing from the grease nozzle with a grease gun. As we all know, grease has a high viscosity. When a grease gun is used to add grease to the inner cavity of the shaft needle roller bearing from the grease nozzle, the resistance is very large, and the grease pressure increases, pushing open the pressure reducing valve opposite the grease nozzle and overflowing.

This phenomenon can also make the driver and repairman mistakenly believe that the grease has been filled. In fact, the grease has not entered between the needle rollers. When dismantling for maintenance, even if the grease is forcibly applied to the needle rollers and the journal surface, it can play a certain lubricating role. However, in terms of actual lubrication effect, calcium-based grease is far inferior to gear oil. The reasons are:

a. Universal joints have to withstand large torque and alternating loads during operation, but the oil film of calcium-based grease has poor toughness and it is difficult to form a good oil film on the friction surface of the bearing and the journal.

b. The needle roller bearing of the universal joint cross shaft can only rotate in place during operation and cannot rotate along the steel bowl and the cross shaft neck. The fluidity of calcium-based grease is very poor, so a new oil film cannot be formed immediately after the oil film is destroyed.

c. Calcium-based grease is a mixture of lubricating oil and calcium soap. During use, as the lubricating oil deteriorates and evaporates, the grease will become harder calcium soap. Calcium soap itself not only cannot play a lubricating role, but also hinders the rolling of the needle roller on the journal. Since there is no oil drainage measure in the universal joint cross shaft, the deteriorated grease cannot be discharged and new oil is difficult to inject, which greatly accelerates the wear of the needle roller bearing.

In order to change the wrong practice of using butter instead of gear oil to lubricate the universal joint cross shaft needle bearing, the following maintenance method is recommended.

a. After removing the universal joint cross shaft needle bearing, clean it thoroughly, remove all the residual grease (can be boiled in water or washed in gasoline), soak it in gear oil for 2min~10min, and then install it. It should be noted during use: the oil should be replaced in time after the vehicle wades. The oil should be replaced once every 2000km~3500km. This method has been tested and can extend the life of the universal joint cross shaft needle bearing by 2~3 times.

b. Special hydraulic filling equipment can be used to regularly lubricate the universal joint cross shaft needle bearing of the transmission shaft.