In the automobile maintenance industry, maintenance personnel widely use ordinary grease to lubricate the cross universal joint. According to the research of relevant technicians, this is a wrong practice. Lubrication of Cross Universal Joint
Lubrication of Cross Universal Joint
1. Structural factors of cross universal joint it is difficult to fill the needle roller bearing with grease from the grease nozzle with a grease gun. As we all know, the viscosity of the grease is high.Lubrication of Cross Universal Joint
When the grease gun is used to fill the grease into the inner cavity of the cardan spider needle roller bearing from the grease nozzle, the resistance increases when the grease enters the narrow inner cavity oil passage, and the grease pressure increases.
It overflows by jacking the pressure reducing valve opposite the grease nozzle. This phenomenon can also be mistaken by drivers and repairmen for having been filled with butter. In fact, the butter didn’t get between the needles at all.Lubrication of Cross Universal Joint
2. The physical and chemical composition factors of the butter itself are that the automobile maintenance personnel inject the melted butter into the cross universal joint or make it reach the specified lubrication position. However, due to the characteristics of the butter itself, it can not achieve effective lubrication. This is due to the characteristics of ordinary butter. The details are as follows
A. The universal joint has to bear great torque and alternating load in work, while the oil film tenacity of calcium base grease is poor, so it is difficult to form a good oil film on the friction surface between bearing and journal.Lubrication of Cross Universal Joint
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 cross journal. However, the rolling property of calcium base grease is very poor, so a new oil film cannot be formed immediately after the oil film is damaged.Lubrication of Cross Universal Joint
C．. Calcium based grease is mixed with lubricating oil and calcium soap. During use, due to the deterioration and evaporation of the lubricating oil, the grease becomes a hard calcium soap. The calcium soap itself can not play the role of lubrication, but also hinders the rolling of the roller needle on the journal.
In addition, there are no oil drainage measures in the cross shaft of the universal joint, the modified grease can not be discharged, and it is difficult to inject new oil, The wear of the needle roller joint is greatly accelerated.Lubrication of Cross Universal Joint
According to such characteristics, relevant friends suggest using gear oil lubrication. This is to clean the cross universal joint and then add gear oil. Through comparative experiments, the service life of universal cross joint is two to three times that of ordinary grease. There are also domestic fleets that lubricate the universal cross joint in this way, and the effect is very obvious.Lubrication of Cross Universal Joint
Due to the use of gear oil lubrication, a special pressurized oil filling tool is required, and it needs to be removed and cleaned at the same time. It is troublesome, and the preservation of gear oil is not as good as grease, and its lubrication cycle needs to be shortened. Lubrication of Cross Universal Joint
Therefore, the universal cross joint on the rear transmission shaft of the cutting car should use 2# extreme pressure composite lithium base grease. This is based on two points, Its fluidity is good, so it is easy to reach the lubrication part. Second, it has good extreme pressure resistance, which is suitable for the working state of universal cross joint.
In fact, the maintenance information related to cutting the vehicle requires that it be lubricated with 2# extreme pressure grease (model NLGI2). The use of 2# extreme pressure compound lithium grease should have better effect. It is suggested that DX with old universal cross joint can be tested. If 2# viscosity is still too high, it can be replaced 1#.
In addition, it is recommended to use 2# extreme pressure compound lithium base grease in other parts of the cutting machine. The typical one is the lubrication of steering rod ball joint. The steering rod ball joint of the cutting car is one of the vulnerable parts.
However, due to the special structure of this part, using ordinary butter will certainly affect its service life. This is a place where extreme pressure grease should be used. Therefore, it is also strongly recommended to use 2# extreme pressure compound lithium grease for lubrication.Lubrication of Cross Universal Joint