LOAD-CARRYING CAPACITIES OF GEAR LUBRICANTS OF DIFFERENT CHEMICAL CLASSES BASED ON RESULTS OBTAINED WITH WADD HIGH-TEMPERATURE GEAR MACHINE USED WITH INDUCTION-HEATED TEST GEARS.
AIR FORCE AERO PROPULSION LAB WRIGHT-PATTERSON AFB OHIO
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The WADD High-Temperature Gear Machine and its operation are described briefly. The procedures used with the machine are shown to provide a realistic means of evaluating and screening lubricants for use in aircraft turbine engines operating at elevated gear and lubricant temperatures. A cross section of oils representing different chemical classes of lubricants was used with the WADD High-Temperature Gear Machine in conjunction with induction-heated test gears. The influence of gear material on load-carrying capacity of gears was studied by using two different steel compositions. Also, the effect of gear temperature on load-carrying capacity was investigated at temperatures up to 700F. The data generated on the WADD High-Temperature Gear Machine, when compared with that generated on the Erdco Ryder Gear Machine, indicated that the rates obtained were comparable. When using Standard Ryder gears AMS 6260 and gears made of a high-temperature gear material Nitralloy-N Steel, the load-carrying capacity of a lubricant could not be predicted adequately by using as test gears those composed of an alloy that would be used for the intended application. All of the lubricants evaluated when Nitralloy-N steel test gears were used demonstrated a decrease in load-carrying capacity with increasing gear temperature up to about 400F. Author