Search Results

In consideration of environmental protection, it has recently become necessary to extend the drain intervals of gear oils. For the evaluation of oil life, field tests are generally used, but they are extremely time-consuming and expensive. For gear oils, a laboratory evaluation method mutually related to in-vehicle life has not yet been presented in papers. Because of the importance of evaluating the life of developing oils, the goal of this study was to establish a laboratory evaluation method mutually related to in-vehicle deterioration. With this method, appropriate evaluation is carried out easily and quickly. In our research, we used an FZG gear machine (power circulating gear test rig) to test for T/M (transmission) oil deterioration. The FZG gear machine was operated under severe conditions to accelerate the deterioration of the oil.

Increase of soot contaminated in engine oil caused by EGR system accelerates the diesel engine wear, especially in the valve train. Wear of metal is affected by many factors such as concentration and diameter of soot, oil film thickness, oil characteristics, etc. Effects of soot on metal wear were discussed from the point of view of soot concentration, and soot diameter and oil film thickness. Wear test was carried out by using four-ball wear tester. Consequently, it was made clear that wear increases proportionally to soot concentration, and relation between oil film thickness and soot diameter plays very important role in wear mechanism. Further, the surface of wear scar was observed by SEM to discuss effect of soot diameter on wear and existence of abrasive wear by soot and its occurrence conditions were suggested.