Gear oils: classification and characteristics

Gear oils: classification and characteristics
Gear oils: classification and characteristics
Anonim

Gear oils are a special class of machine oils designed for use in various friction units of vehicle transmissions, as well as in various gearboxes. Engine and transmission oils are produced on a mineral or synthetic basis, and then alloyed with a variety of additives, but the requirements for transmission oils are higher, since they operate at much higher loads and sliding speeds of rubbing surfaces.

Gear oils
Gear oils

One of the most important indicators of such oils is the ability to create a protective film on the surface of friction units to prevent mechanical contact between them. In hypoid gears, oils are used, which, entering into a chemical reaction with the surfaces of parts, prevent their boiling, and have extreme pressure properties. During operation, gear oils oxidize and become contaminated, so they must be changed periodically. A good oil is one with a low tendency to oxidize. Since different manufacturers use different additives, you cannot mix their products. When replacing the transmission unit, it must be thoroughly flushed, if possible with the same fresh oil.

Classifygear oils either by viscosity or performance properties. So according to the SAE (Association of Automotive Engineers), they are divided into nine classes - five summer and four winter (with the W index). For each class, a viscosity index is indicated. SAE 70W or SAE 250 for example. For multigrade oils, a double index is indicated (SAE 80W-90, etc.).

API (American Petroleum Institute) divides oils into 6 classes depending on performance properties - GL-1…GL-6. These classes are similar to those used in the Soviet GOST 17479.2-85 TM1 … TM6. The fifth and sixth groups are used for hypoid gears and have the highest lubricity and extreme pressure performance.

engine and transmission oils
engine and transmission oils

When choosing gear oils, you should focus primarily on their operating conditions. If the grade is lower than necessary, the mechanism will simply fail, and a higher grade of oil has a higher cost, which will lead to cost overruns. It is also important to consider at what temperatures the transmission will operate, and based on this, select a lubricant. SAE 85W, for example, will work at temperatures down to -12°C, and 85W already down to -40°C. Automatic transmissions use a special low-viscosity fluid, so no engine or transmission oil is used.

Lukoil gear oils
Lukoil gear oils

Today, a wide range of manufacturers offer their gear oils on the market - Lukoil, Total, Texaco, Reksol, Norsi and many others. The variety of additives used determines how the levelquality oils, and their price range. Mineral, as a rule, costs less, but serves less, synthetics are exactly the opposite. A good compromise in this case would be semi-synthetics, as the golden mean between the first two. You should also beware of fakes and do not buy oils in unverified stores. Changing a gearbox is always more expensive than taking a good, high-quality oil, especially since now they take 60,000 or more kilometers from replacement to replacement.

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