2. Different lubrication regimes in lubricated contacts

In the case of lubricated bearings, the curve of variation of friction with speed generally has the form given in 2 . This curve is more complete than that obtained experimentally by Stribeck in 1902 [3], since the hydrostatic case and part IV at high speed have been added since that date, and have only been known since the 1950s. Similarly, the nature of the lubricants is not specified, and the scales are not plotted on the axes, as these values depend on the shape of the contact and the lubricants. This curve is representative of all lubricated contacts and can also be obtained for Hertzian contacts such as ball and roller bearings and gears; however, for these mechanisms, the hydrostatic part and zone IV do not exist.