Effects of Lubricants, Metals, Temperature, and Atmospheric Environments on Gear Load-Carrying Capacity

Experimental gear load-carrying capacity results are presented for three different gear materials and a variety of lubricants of different chemical classes and viscosities, with emphasis on high-temperature operation in air and nitrogen environments. The lubricant-metal-atmosphere interaction was found to be complex and could not be predicted by simple means. With a given gear material in an air environment, load-carrying capacity was found to decrease with increasing temperature until a minimum value was reached, and then to increase with further increase in temperature. A substantial reduction in load-carrying capacity was noted when the air environment was replaced with nitrogen. In addition, the increase in load-carrying capacity noted at high temperatures in air environment was not observed when nitrogen environment was used. This general behavior was, however, quite different when another gear material was used.