Antiwear and Extreme Pressure Additives for Greases

Twenty-nine additives were evaluated for their antiwear and extreme pressure properties when incorporated in various percentages in lithium soap-mineral oil greases. The percentages of the principal antiwear and extreme pressure inducing elements: sulfur, chlorine, phosphorus and lead were determined. The most promising ones were further evaluated in commercial greases and in inorganic thickened diester greases. Evaluations were based upon the Four-ball wear and EP, the Falex, and the Timken testers. Results indicate that phosphorus imparts antiwear properties while sulfur, chlorine, and lead, give EP properties to greases. Combinations of additives would enhance both properties. Increase in the additive concentration gave increased values to the results. The type of grease had an effect upon the efficiency of the additive thus indicating the need to fit the additive to the type and intended use of the grease. Contributed by the ASLE Technical Committee on Properties of Lubricants and presented at the Ann...