Online ISSN : 2189-9967
Print ISSN : 0915-1168
ISSN-L : 0915-1168
Volume 57 , Issue 9
Special Issue on Tribology in Engines for Low Fuel Consumption and Clean Exhaust Gas
Showing 1-14 articles out of 14 articles from the selected issue
Serial Messages to Tribologists
A Round Table Talk: Green Tribology
Special Issue on Tribology in Engines for Low Fuel Consumption and Clean Exhaust Gas
Original Contribution
  • Akihiko YANO, Yo AKIYAMA, Miharu MATSUOKA, Kazufumi TAKAYANAGI
    2012 Volume 57 Issue 9 Pages 637-645
    Published: September 15, 2012
    Released: February 05, 2020
    Generally synthetic gear oils have superior oxidation stability compared to mineral gear oils, although there is a concern that the oil life may depend on the sludge formation during its oxidation process. In the methods of ASTM D2893 or ASTM D5763 which are commonly used as oxidation tests of gear oils, the test duration for degradation is specified 312 hours. Considering the evaluation to select synthetic gear oils, the test duration is too short to find the significant difference since the degradation of synthetic gear oils would be minimal. The authors provide a new method, in which gear oils are oxidized and degraded by modified dry-TOST (dry-Turbine Oil Oxidation Stability Test) method without catalysts, and use the RPVOT (Rotating Pressure Vessel Oxidation Test) residual ratio as the newly introduced degradation index. This study shows the RPVOT residual ratio has a correlation with changes of kinematic viscosity or acid number which are generally used as the degradation index, and also presents that degradation tendency of the gear oils can be classified by the relationship graph between RPVOT residual ratio and sludge quantity.
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