Abstract
Mechanical elements under high surface pressure that accompanies abrupt acceleration or deceleration and/or increases in load can easily en in a lubrication state close to dry friction. In this condition, the lubricating oil needs addition of some EP (Extreme Pressure) additives, such as Cl-additives, P-additives, S-additives and their blended-Additives which have been used as typical EP additives. Generally speaking, sulphur type additives have most scaffing resistance in these additives, and phosphorus type additives and Chlorine type additives are next to that. And sulphur type additives have wear durability that is inferior to phosphorus type additives. In our experiment, wear durability of sulphur type additives in our step loads under high pressure for steel to steel contact was investigated by using a four-ball tester.
