Effect of Engine Operating Environments on Lubricant Load Carrying Capacity of High Gear Load Oils

摘要

Load carrying capacity evaluations were made on current and advanced esterbased synthetic lubricants which were exposed to the operating environments of gas turbine engines. The program also investigated the cause/effect of changes in load carrying capacity as related to additive depletion and possible additive/metal interaction through an adsorption or reactive process. The results indicated that both current oils and advanced high gear load oils experienced significant degradation in load carrying capacity with time in both engine and simulated engine bearing compartment environments. The percentage loss in load carrying capacity was greater with the high gear load oils, but neither oil was significantly influenced by the engine type sampled. However, the absolute rating of the degraded XAS-2354 oil remained above the degraded MIL-L-23699 oil absolute ratings. The lower load carrying capacity of used oils, attributed to additive depletion, appeared to be recoverable with new oil additions of a high gear load oil. However, this capability would not be realized in normal operation of an engine lubrication system. An effective pre-conditioning treatment of gear tooth surfaces with a high gear load oil was demonstrated and recommended for use in the 'run-in' of new or overhauled helicopter gearboxes for improved resistance to surface damage and extended service life. (Author)