1. Good extreme pressure, that is, under the lubricatio […]
1. Good extreme pressure, that is, under the lubrication condition that the friction surface contact pressure is very high and the oil film is easily broken, it can prevent the friction surface damage such as sintering and welding. Extreme pressure improvement must rely on extreme pressure additives, which are compounds containing molecules such as chlorine, sulfur, phosphorus, etc., which chemically react with the metal surface of the gear when the temperature of the friction surface is high enough. The iron chloride, iron sulfide, iron phosphate film, the critical shear strength of the solid film is lower than that of the base metal, and the shearing motion of the friction pair is performed in the solid film to prevent gluing or scratching on the metal surface.
2. Appropriate viscosity. Under normal operating conditions, the gear surface of the vehicle is often in an elastic hydrodynamic lubrication state. At this time, the viscosity of the gear oil has an important influence on the bearing capacity. The viscosity of the oil is high, the thickness of the elastic fluid dynamic lubricating oil film is thick, and the bearing capacity of the gear oil is high, which is advantageous for the tooth surface protection, but the viscosity is not as high as possible. Because the gear oil is agitated while the gear is working, the internal friction of the liquid generates frictional heat, which will raise the oil temperature. As the oil temperature rises, the overall gear temperature and the tooth surface temperature increase, and the oil film is easily destroyed. Therefore, the viscosity of the gear oil should not be too large. Therefore, the viscosity of the gear oil should be appropriate. Specifically, the following requirements should be met. The maximum viscosity at the minimum working temperature must ensure that the car can start smoothly without preheating; under normal operating conditions, the internal friction consumption of the gear oil should not be The power delivered is significantly reduced; the viscosity at the highest operating temperature must ensure reliable lubrication of the gears.
3, good viscosity temperature performance. That is, as the operating temperature changes, the viscosity change should be as small as possible to ensure sufficient fluidity at low temperatures, and a sufficient amount of oil is brought to the tooth surface and bearing when the gear rotates to prevent damage. The viscosity does not decrease too much at high temperatures, and it is necessary to form a sufficiently thick lubricating oil film.
4. In addition to the above performance requirements, the vehicle gear oil should also have good thermal oxidation stability and anti-foaming properties, be less corrosive to metals, and have better storage safety.