Abstract: Extreme pressure (EP) additives are used when components are operated under extreme pressure. This work studies the effect of base oils on the tribological performance of EP additives. The difference between the absorbability of the EP additives and that of base oils dominates the mutual compatibility and performance of the EP additive. When used, the EP additive forms a saturation layer on the rubbing surfaces. The concentration of EP additive in the saturation layer exceeds the additive concentration in the lubricants. Therefore, during operation, the protecting layer can reduce the contacting stress of rubbing surfaces by chemical and physical methods to prevent local plastic deformation from inducing serious wear. Under the harshest conditions, the immediate formation of films in a chemical reaction is important when plastic deformation of the contact region cannot be avoided. The high rate of formation of chemical films can prevent direct metal-to-metal contacts to reduce wear. A comparative account of performance of the tested compounds is presented on the basis of various tribological parameters such as initial seizure load, 2.5 s seizure delay load, weld load, mean Hertz load, flash temperature parameter, pressure wear index, friction coefficient (m) and wear scar diameter (d), etc. All the tested complexes have been found to possess significant Extreme Pressure (EP) efficiency under the experimental conditions of four ball test. In paper evaluated and investigated of tribological properties of SAE 60 lubricating oils without using extreme pressure additives.
Keywords: Lubrication, wear, Extreme pressure (EP) additives, four ball extreme pressure tester, Additives.