The universal joint cross needle roller bearings of the drive shaft should be lubricated with gear oil. However, it is generally found in automobile maintenance that the universal joint cross shaft needle roller bearings of the propeller shaft are lubricated with calcium-based grease (commonly known as butter).
Actually, this lubrication method is wrong, resulting in a large number of cross shaft needle roller bearings. Early damage. In the disassembly, it can be clearly seen that the cross shaft journal presents a groove that is squeezed in, and the shaft journal and the needle are seriously short of oil.
Why would such phenomenon happen? It is because the lubricating nipple of the universal joint cross shaft needle roller bearing is an ordinary grease nipple, which gives people an illusion, and it has been common to add grease for lubrication for a long time. Coupling In fact, it is difficult to fill the needle bearing with grease using a grease gun from the grease nipple. As we all know, the viscosity of butter is large.
When the grease gun is used to fill the inner cavity of the universal joint cross needle roller bearing with grease from the grease nipple, the resistance increases when the grease enters the narrow cavity oil passage, and the pressure of the grease rises and opens the opposite side of the nipple.
The pressure reducing valve overflows. This phenomenon can also be mistaken by drivers and repairers for being filled with butter. In fact, the butter does not enter between the needles at all, and it is very difficult to reach the end face of the cross shaft journal.
When removing and repairing, even if using a forced method to apply butter on the surface of the needle and journal, it can also provide some lubrication, but for the lubrication effect of the cross shaft needle roller bearing, the calcium-based grease is far inferior to the gear oil it is good.
The reason is: 1. Universal joints have to withstand large torsional forces and alternating loads during work, and the oil film of calcium-based grease is poor in toughness, and it is difficult to form a good oil film on the friction surface of the bearing and the journal. 2. The needle roller bearing of the universal joint cross shaft can only rotate in situ during work, and cannot rotate along the steel bowl and the cross journal. The rolling performance of calcium-based grease is very poor, so when the oil film is destroyed, it cannot be formed immediately New oil film. 3. Calcium-based grease is a mixture of lubricating oil and calcium soap. In use, due to the deterioration and evaporation of the lubricating oil, the grease turns into a harder calcium soap.
The calcium soap itself cannot provide lubrication. , And it also hinders the rolling of the needle on the journal. In addition, there is no oil drainage measure in the universal joint cross shaft.
The deteriorated grease cannot be discharged, and the new oil is difficult to inject, which greatly accelerates the Wear of the joint cross shaft needle roller bearings.
In order to change this wrong approach of using butter instead of gear oil to lubricate universal joint cross shaft needle roller bearings, the following maintenance methods are recommended to improve the service life of universal joint cross shaft needle roller bearings.
a. Remove the universal joint cross shaft needle roller bearings and clean them thoroughly, remove all the remaining grease (can be boiled in water or put in gasoline to clean), soak in gear oil for 2min -l0min, then install it. . Attention should be paid in use: the car should be replaced with new oil in time after wading. New oil should be replaced once when driving 2000km-3500km. This method has been tested and can extend the life of universal joint cross shaft needle roller bearings by 2 to 3 times.
b. It can be equipped with special hydraulic filling equipment to regularly lubricate the universal joint cross needle roller bearings of the drive shaft
