If special alloys are used in one or both members of a gear set, special consideration may be necessary in choosing a lubricant. The supplier of the equipment will no doubt have the answer since, as Forbes et al. ^20 states:
“The choice of metals that will operate together in a particular type of reduction gear is based on practical data that have been secured by trial and error methods over a period of years.”
It is known that some steels are more difficult to lubricate than others. Stainless steel is very important in this time. Some alloys will not react readily with certain EP elements. Chromium is practically inert to sulfur compounds but will react with most chlorine compounds. Therefore, with high nickel-chrome-molybdenum alloy steels it is important that an EP lubricant contain chlorine additives as well as sulfur compounds.
