In addition to good friction and wear resistance, the requirements for lubricating materials of automobile transmission shaft cross bearing should also have good mechanical stability, high temperature resistance (high drop point), corrosion resistance, water resistance and oxidation stability.
The high temperature and water resistance of gear oil cannot meet the requirements. In addition to calcium grease (hereinafter referred to as calcium grease), there are lithium grease (hereinafter referred to as lithium grease), aluminum grease and sodium grease. In fact, No. 2 or No. 3 lithium-based grease has always been used for the lubrication of automobile transmission system, because lithium-based grease has higher drop point (170 ℃ - 190 ℃ for lithium-based grease and 90 ℃ - 100 ℃ for calcium-based grease) and better thermal stability compared with calcium-based grease.
The technical requirements for dismantling the cross needle roller bearing are relatively high. Generally, it needs to be completed by a professional repairman in an automobile repair shop. The lubrication of the transmission shaft spider is a routine maintenance item, which is generally maintained every 2000km. If every maintenance is carried out in the repair shop, it will undoubtedly increase the economic burden of the owner; If each vehicle is equipped with a special hydraulic filling device, it is also unrealistic. With grease lubrication, the driver can complete it with only one ordinary grease gun, saving time and economy.
However, some drivers operate incorrectly, which will cause the grease to not enter the bearing. The correct operation method is to press the oil outlet of the grease gun tightly on the grease nozzle, and operate the grease gun continuously to make the grease enter the oil passage inside the cross shaft through the grease nozzle under the pressure, and then reach the four journal end faces of the cross shaft, fill all needle roller bearings, and at the same time, extrude the residual deteriorated grease and impurities in the needle roller bearing from the oil seal. After all the deteriorated grease and impurities in each bearing are squeezed out (see fresh grease being squeezed out), the operation is completed. If the grease cannot be pressed into the bearing during operation, replace the grease fitting or remove the cross shaft to clean the oil passage, and then fill it to ensure driving safety.
In addition, with the continuous development of the automobile industry, molybdenum disulfide grease is widely used in the automobile industry. The so-called molybdenum disulfide grease is made by adding a small amount of colloidal aluminum disulfide into lithium grease or complex calcium grease. Molybdenum disulfide is lamellar crystal, and its sulfur atom has a strong affinity for metal, so it is easy to form a solid lubricating oil film on the friction surface.