Abstract:Abstract: The characteristics and law of spur gears meshing were analyzed based on the elastohydrodynamic lubrication. Then a MATLAB/Simulink model was proposed for the prediction of mechanical dynamic efficiency of spur gear pairs by investigating on the computational formulas of key factors such as friction coefficient, load distribution, film thickness and so on. A period defined from the start point of meshing to the end point of meshing along line of action was divided into four parts which for an easier computation of the average sliding and rolling power losses. Meanwhile, a modifying factor was rationally introduced to account for the effect of variable lubricant viscosity. The simulation results were compared with test data and the results from other prediction models. The comparative results show that the proposed prediction model is accurate.