The Determination of the Pressure-Viscosity Coefficient of a Lubricant Through an Accurate Film Thickness Formula and Accurate Film Thickness Measurements. Part 2: High L Values

The pressure–viscosity coefficient of a traction fluid is determined by fitting calculation results on accurate film thickness measurements, obtained at different speeds, loads, and temperatures. Through experiments, covering a range of 5.6 < M < 12 000, 2.1 < L < 17.5, film thickness values are calculated using a numerical method and approximation formulas from 12 models. It is concluded that, to assess the pressure–viscosity coefficient of the fluid, the Chittenden et al. approximation formula applied to circular contacts is the best choice, having an inaccuracy in between (−15%, +11%). This expression has been used far outside the regime of the numerical data where it was based upon.