Transmission oils: classification and characteristics
Transmission oils - special classmachine oils, intended for use in different friction nodes of vehicle transmissions, as well as in various reducers. Motor and transmission oils are produced on a mineral or synthetic basis, and then alloyed with a variety of additives, but the requirements for transmission are higher, since they work at much higher loads and sliding speeds of rubbing surfaces.
Classify gear oils orviscosity, or performance properties. So on SAE (Association of Automotive Engineers) they are divided into nine classes - five summer and four winter (with the index W). For each class, the viscosity index is indicated. SAE 70W or SAE 250, for example. For all-season oils, a double index is indicated (SAE 80W-90, etc.).
API (American Petroleum Institute) sharesOil for 6 classes depending on the operational 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 lubricating and extreme pressure characteristics.
When choosing transmission oils,focus on the conditions of their work. If the class is lower than necessary, the mechanism will simply fail, and a higher grade of oil will have a higher cost, which will lead to a cost overrun. It is also important to consider at what temperatures the transmission will work, and proceeding from this to select the lubricant. SAE 85W, for example, will operate at temperatures down to -12 ° C, and 85W already up to -40 ° C. In automatic transmissions a special low-viscosity liquid is used, therefore neither motor nor transmission oil is used there.