Correct Maintenance of Universal Joint Cross Axle Needle roller bearing

The universal joint cross axle needle roller bearing of the transmission shaft should be lubricated by gear oil. But the universal joint cross axle needle roller bearing of the transmission shaft is usually lubricated by lime grease (usually called consistent grease) in car maintenance. In face, this kind of lubrication mode is wrong. It can make large quantities of cross axle needle roller bearings be damaged in early period. When taking down, extruded groove can be clearly seen on the cross axle journal, and severe oil starvation happens on the journal and rolling needle.

Why does the phenomenon appear?

This is because the grease fitting of the universal joint cross needle roller bearing is only a common grease fitting. So it makes people under an illusion that the needle roller bearing is lubricated by grease.

In fact, it is difficult for grease gun to fill the needle roller bearing with grease from the grease fitting. As is known to all, grease is provided with high viscosity. When fill the universal joint cross axle needle bearing intracavity with grease by grease gun and grease enters into the narrow intracavity oil canal, the resistance increases, and the grease pressure also increase. The reducing valve opposite to the grease fitting is opened by the grease pressure, and the grease overflows. This phenomenon may be mistaken by driver and repairman that abundant oil is filled. In fact, grease does not enter among the rolling needles at all, and it is very difficult for grease to reach the cross axle journal end surface. When taking down and repairing, even forcible methods such as smearing grease on rolling needle and journal surface can function as lubricant. But for the lubricating effect of cross axle needle roller bearing, lime grease is far worse than gear oil, the cause is as follow:

a. the universal joint is subject to great torsion and alternate load when working, but the oil film of lime grease is provided with bad toughness, and it is difficult to form good oil film on the friction surface between bearing and journal.

b. the needle roller bearing of the universal joint axle can only in situ rotate when working, and it can not rotate along the cup and cross axle journal. The lime grease is provided with bad rolling characteristics, and new oil film can not be formed at once when the oil film is destroyed.

c. the lime grease is mixed by grease and calcium soap. Because the lubricant deteriorates and evaporates in use, the grease becomes hard calcium soap, but calcium soap can not function as lubricant, and it impedes the rolling needle to roll on the journal. Besides, the universal joint cross axle is not provided with oil drain measures, the deteriorated lubricant can not be discharged, and new grease can not be filled in, so the wearing of the universal joint cross axle needle roller bearing is greatly accelerated.

To change the wrong practice of lubricating universal joint cross axle needle roller bearing by grease instead of gear oil, it is suggested to adopt the following maintenance methods to enhance universal joint cross axle needle roller bearing life.

a. remove the universal joint cross axle needle roller bearing and thoroughly clean it. Clean all the surplus grease (can be boiled in water or washed in petrol. Then dip the bearing in gear oil for 2min to l0min, and it can be mounted and used now. Please pay attention to the following things: replace the grease with new one after the automobile runs in water. Replace the grease with new one after the automobile runs 2000km to 3500km. After being tested, this method can extend the universal joint cross axle needle roller bearing to 2 to 3 times.

b. can be matched with special hydraulic filling device to regularly lubricate transmission shaft of the universal joint cross axle.