Dalan Motor analyzes the 4 major reasons for the discoloration of the bearing grease of the hydraulic oil pump motor.

After disassembling a hydraulic oil pump motor, it was found that the grease in the motor bearing changed from milky white to silver gray. What caused this problem? Is the discoloration of bearing grease normal? What is the normal color of grease? The editor of Dalan Motor will answer all of them today.

Grease discoloration in bearings is sometimes discolored even if it is not placed in the motor bearings. This is because:

First, grease has oxidation problems. When the grease is placed (or operated) for a period of time, it will have a lot of contact with oxygen, and now many greases have antioxidant additives. This does not mean that there will be no oxidation.

Secondly, the temperature of the motor bearing itself (the motor bearing itself, or the environment) will change, which causes the base oil in the grease to continuously flow in and out of the thickener, and each time the base oil returns, it may not necessarily go back completely. After a long time, the performance of the grease will change and it will not be able to meet the lubrication, so it is necessary to reapply the lubrication. If the temperature is abnormal, the performance of the grease will also change greatly, so that it will change color. If the temperature is high, it will carbonize. The color will become darker.

Third, during the operation of the bearing, impurities are mixed into the grease. This kind of impurities may be peeled off by the bearing itself, or it may be entered by the outside. It may be solid or liquid. These will affect the properties of the grease.

Fourth, tight fit, small clearance, causing discoloration of grease. This reasoning should be such that the fit is tight, the working (remaining) clearance is small, the bearing load area is increased, and heat is generated, which causes the degeneration of the grease and the color of the grease.

Of course, according to the color of the grease to determine whether the situation is normal. Judgment on this point is very difficult, and the specific measurement must be made by instruments. Different greases have different internal additives, different operating conditions, and different temperature ranges. It is impossible to have a unified specification. Even the same type of grease may have slightly different formulations due to different batches. Please do not use this color change as a basis, which is unreliable.




----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant

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