Flow of Electric Current Through Lubricated Contacts

Abstract

A study is made of the passage of current, both DC and AC, through elastohydro-dynamically lubricated contacts using a 4-ball machine running at 175 rpm with 1 in Steel balls. At small applied voltages ∼15mV, when there is a coherent oil film, (i.e., when it is not short circuited by metallic contact) it behaves as an ohmic resistance. The resistance of the oil film varies from >101 ohms down to 1 ohm. This has important implications for the concept of percentage metallic contact, and for the statistical contact method of assessing oil film thickness. At high currents (∼1 amp.) the current flows by the voltage discharge mechanism. The transition from ohmic resistance to discharge is discussed. Using the resistance of the oil film the lubricating quality of long chain acids in cetane is compared. A brief study is also mode of Fein's temperature correlation.