Observation of Lubrication State and Lubricant Replenishment under Sliding-Rolling Motions with Single-Charging Amount

Using a ball-on-disc film and friction measurement apparatus, the lubrication states, and lubricant replenishment behaviors were experimentally observed under sliding-rolling conditions with single-charging amount. The results showed that for a fixed sliding-rolling-ratio (SRR), the transitions of contacts from boundary lubrication to elastohydrodynamic lubrication (EHL) were found, the trends of which were highly dependent on the lubricant charging amount. The out-of-contact replenishment mechanism was responsible for the transitions. Given entrainment velocity, the inlet distance decreased and starvation width broadened with variations of SRR from a negative value to a positive value, which was attributed to the large differences of replenishment time. Under fully starvation states, the contact replenishment mechanism played a significant role in the establishment of local EHL films.